2nd Edition of the Workshop 'Quarkonia meet Dark Matter' (QMDM)

18 Mar 2024, 07:10 → 22 Mar 2024, 23:20 Europe/Berlin

Auditorium (Institute for Advanced Study, Technical University of Munich)

Tobias Binder, Nora Brambilla (Physik Department, TU Munich), Stefan Lederer (Technische Universität München), Gramos Qerimi (TUM), Antonio Vairo

Overview:

The second edition of the theory workshop "Quarkonia meet Dark Matter" continues to provide particle physicists a platform for exchanging knowledge and methodologies at the intersection of both fields. In the spirit of the first edition in 2021, this workshop aims to foster interdisciplinary collaborations, to expand field horizons, to generate new research directions, as well as to solve open problems by applying novel concepts from one field to another. Key scientific topics on the intersection include effective quantum field theories for heavy quark-antiquark states inside the quark-gluon plasma and dark matter pairs in the early Universe, non-equilibrium quantum field theories for describing the system's dynamics such as the open quantum system and the Keldysh-Schwinger formalism, as well as effective field theories in the strongly coupled regime and other techniques for describing phase transitions of QCD at colliders and of new physics particles in the early Universe, such as dark sectors and their associated gravitational waves production.

Zoom broadcast:

The contributed talks will be broadcast online via zoom, accessible here: 
   Link
<https://tum-conf.zoom-x.de/j/69613205773?pwd=SzZyTEEvUU8vbHBNVnptZTZ2ZlRuQT09>.

 

Informal Social Dinner:

The informal social dinner will take place on Wednesday at 19:30 (7:30pm) at "Gasthof Neuwirt" in Garching. We can easily get there taking one stop on the subway ("U-Bahn") from the station close to the workshop venue. There will be a small à-la-carte menue with specialties of the house. 
Tickets for the subway can be bought at the machines on the platform or via App (see for example: https://www.mvg.de/services/mobile-services/mvgo.html) 

Gasthof Neuwirt:
Adress: Münchener Str. 10 • 85748 Garching
webpage: https://www.gasthof-neuwirt.org/
 

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This workshop is supported by

     

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QMDM2024_GroupPhoto_crop.jpg

QMDM2024_GroupPhoto.jpg

QMDM2-ConferencePoster.pdf

Monday 18 March

09:00 → 09:10 Opening

Welcome and general overview of the workshop week.
Meta-information on schedules and resources.

Speakers: Antonio Vairo (TUM), Gramos Qerimi (TUM), Nora Brambilla (Physik Department, TU Munich), Stefan Lederer (Technische Universität München), Tobias Binder (TUM)

Intro_QMDM2024.pdf

09:10 → 10:20 Monday - Session 1

Convener: Tobias Binder (TUM)

09:10 Quarkonium meets Dark Matter

We review nonrelativistic effective field theories for
quarkonium at and out of equilibrium emphasizing their utility also in
describing dark matter pairs near threshold and their evolution in
the early universe.

Speaker: Antonio Vairo (TUM)

QMDM24.pdf

09:45 Electroweak Multiplets as Dark Matter candidates: a status review

In this talk, my objective is to present the phenomenology of Electroweak multiplets as potential Dark Matter (DM) candidates in the coming years, with a specific focus on detection possibilities at the muon collider. To begin, I will delve into the thermal production mechanism in the early Universe and provide an overview of the current phenomenological landscape concerning the search for Weakly Interacting Massive Particles (WIMPs). It is important to note that WIMPs continue to be a viable DM candidate with significant phenomenological implications in the foreseeable future. Subsequently, I will describe the main properties of Electroweak multiplets as DM candidates, which serve as prototypes for WIMP DM. Specifically, I will illustrate how to compute the thermal masses, taking into account significant non-perturbative non-relativistic effects such as the Sommerfeld enhancement and the formation of DM bound states. Finally, I will conclude with the phenomenology of EW multiplets by emphasizing that a synergy between cosmological probes and the muon collider is needed to say a final work on this crucial class of DM candidates.

Speaker: Paolo Panci (Università di Pisa & INFN Pisa)

StatusEWmultiplets_PANCI.pdf

10:20 → 10:50 Coffee Break

10:50 → 12:10 Monday - Session 2

Convener: Stefan Lederer (Technische Universität München)

10:50 Dark matter, bound states and unitarity

If dark matter couples to force mediators that are much lighter than itself, then its interactions manifest as long-ranged. This gives rise to non-perturbative effects, including the existence of bound states. The formation of stable or metastable dark matter bound states can affect the dark matter phenomenology very significantly, including the dark matter relic density, indirect and direct detection signals, as well as the dark-matter self-scattering inside galaxies. I will give an overview of the effect of bound states on the dark matter production in the early universe, and discuss the connection to unitarity.

Speaker: Kallia Petraki (ENS and Sorbonne University)

Petraki_BoundStatesDMunitarity.pdf

11:25 The sommerfeld enhancement at NLO

We reexamine the consequences of perturbative unitarity on dark matter freeze-out when both Sommerfeld enhancement and bound state formation affect dark matter annihilations. At leading order (LO) the annihilation cross-section is infrared dominated and the connection between the unitarity bound and the upper bound on the dark matter mass depends only on how the different partial waves are populated. We compute how this picture is modified at next-to-leading order (NLO) with the goal of assigning a reliable theory uncertainty to the freeze-out predictions. We explicitly compute NLO corrections in a simple model with abelian gauge interactions and provide an estimate of the theoretical uncertainty for the thermal masses of heavy electroweak n-plets. Along the way, we clarify the regularization and matching procedure necessary to deal with singular potentials in quantum mechanics with a calculable relativistic UV completion.

Speaker: salvatore bottaro (Tel Aviv University)

Bottaro.pdf

11:50 Radiation back-reaction during dark-matter freeze-out via metastable bound states

The formation and decay of metastable dark matter bound states in the early universe can deplete the dark matter abundance, thereby affecting the predicted couplings and mass. The efficacy of the effect is suppressed by the ionisation and excitations of bound states due to the ambient radiation. While existing calculations take into account the thermal radiation, the dynamics of Hydrogen recombination suggests that the resonant radiation produced in capture processes may backreact, dissociating bound states and impeding the dark matter depletion. We investigate the backreaction of resonant radiation, as well as of higher-energy radiation produced by dark matter annihilation and bound-state decays in this context.

Speaker: CHRISTIANA vasilaki (LPENS)

PresentationChristianaVasilaki.key

PresentationChristianaVasilaki.pdf

12:10 → 13:35 Lunch Break

13:35 → 15:25 Monday - Session 3

Convener: Gramos Qerimi (TUM)

13:35 Quantum theory of dark matter scattering

A long-range force between dark matter particles makes significant impacts on dark matter phenomenology.
It enhances the annihilation cross section at the late Universe (Sommerfeld enhancement), which affects the prospects for detecting annihilation products (indirect detection experiments).
It also leads to a large self-scattering cross section, which forms a significant core in dark matter halos.
These two effects exhibit an interesting correlation: for example, when the Sommerfeld enhancement factor is significantly large for a certain value of the parameter (resonance), the self-scattering cross section is also resonantly enhanced.
In this talk, we first review how the Sommerfeld enhancement factor and self-scattering cross section are computed by using a scattering state in quantum mechanics.
Then, we formulate the relation between these two effects and discuss how the correlated resonance is understood in our formulation.

Speaker: Ayuki Kamada (University of Warsaw)

kamada0318.pdf

14:05 Enhancement of p-wave dark matter annihilation by quasi-bound states

We examine the Sommerfeld enhancement in dark matter pair annihilation, scrutinizing p- and higher ℓ-wave annihilations. We focus on the Yukawa potential, noting unexpected velocity scaling and resonant behavior, attributed to the presence of quasi-bound states. We provide a quantum mechanical explanation for the phenomenon and for its features using the WKB approximation. We examine the impact of quasi-bound states for Wino dark matter and DM models with light mediators, discussing implications for relic abundance and indirect detection signals.

Speaker: Lorenzo De Ros

presentazione.odp

presentazione.pdf

presentazione.pptx

pWave.avi

sWave.avi

14:25 Electroweak resummation of neutralino dark-matter annihilation into high-energy photons

We consider the resummation of large electroweak Sudakov logarithms for the annihilation of neutralino DM with $\mathcal{O}$(TeV) mass to high-energy photons in the minimal supersymmetric standard model, extending previous work on the minimal wino and Higgsino models. We find that NLL resummation reduces the yield of photons by about 20% for Higgsino-dominated DM at masses around 1 TeV, and up to 45% for neutralinos with larger wino admixture at heavier masses near 3 TeV. This sizable effect is relevant when observations or exclusion limits are translated into MSSM parameter-space constraints.

[arXiv:2211.14341]

Speaker: Stefan Lederer (Technische Universität München)

QMDM2-MSSM_Lederer_v4+backup.pdf

14:50 The Future of Thermal Relic Dark Matter

The idea that dark matter is nothing more than a “heavy neutrino” that froze out after reheating has long been a seductive one. Indirect detection experiments are just now entering an era where the simplest candidate thermal relic models can be excluded. We will survey the status of current & near-future observations of the galactic center and dwarf spheroidal galaxies to rule on low-dimensional representations of SU(2) as dark matter. We will then discuss efforts to build and test a wider class of thermal-relic candidates whose mass can range up to the Planck scale.

Speaker: Prof. Matthew Baumgart (Arizona State University)

hdmTUM.key

hdmTUM.pdf

15:25 → 15:55 Coffee Break

15:55 → 17:55 Monday - Session 4

Convener: Peter Vander Griend (University of Kentucky and Fermilab)

15:55 Potential non-relativistic effective field theories for dark matter particles

The evidence for dark matter is perhaps of the strongest call for new physics. On top of being desirable from the phenomenological and observational points of views, the possibility of a richer dark sector, that comprises more than one particle, is fairly common in many DM models. The dark particles can enjoy their own hidden forces, which are far less constrained than the interactions between DM and Standard Model (SM) degrees of freedom. Furthermore, the existence of light mediators may affect the DM dynamics in multiple ways. Most notably, whenever DM particles are slowly moving with non-relativistic velocities, light mediators can induce bound states in the dark sector in the early universe and/or in the dense environment of present-day haloes.

From here, the need to tackle and have under control the dynamics of dark matter pairs, that qualify as a typical multi-scale system. We show how pNREFTs can be built for a variety of force mediators, and how bound-state calculations can be then carried out in a very similar way to the ordinary quantum mechanics, however enriched with the full strength of quantum field theory at zero and finite temperature. Our approach is based on the renowned NREFTs of this sort that have been obtained for QED and QCD, and served as precious and handy tools for rigorous and systematic analyses of e.g. hydrogen atom, positronium, heavy quarkonia, heavy-light hadrons or muonic hydrogen.

Speaker: Simone Biondini

Biondini_QMDM_2024.pdf

16:30 Center-of-mass recoil effects for thermal dark matter pairs in the early universe

For a quantitative investigation on the time evolution of heavy thermal dark matter at and after thermal freeze-out, near-threshold processes need to be taken into account which have a large impact on the observed dark matter relic abundance. We study the recoil effect of heavy dark matter pairs in a thermal bath and compute the thermal rates of dark matter fermion-antifermion pairs in the laboratory frame within the framework of potential non-relativistic effective field
theories at finite temperature. For the considered hierarchy of energy scales, we highlight the effect of the recoil corrections to the thermal rates and relic density.

Speaker: Gramos Qerimi (TUM)

slides_qerimi_18032024.pdf

16:55 Perturbative high order calculation of DM and quarkonium

Speaker: Benoit Assi (U Hamburg)

QQDM_2024.pdf

QQDM_2024.pdf

17:15 Debye mass effects in the Dark Sector in the Early Universe

In this work, we address the impact of the thermal Debye mass 𝑚𝐷 scale on the bound-state formation and ionization (dissociation) in the dark sector in the Early Universe. We focus on heavy dark fermions (with mass 𝑚) charged under a 𝑈(1)𝑑 group coupling dark matter to dark photons and dark light fermions with the coupling constant 𝛼=𝑔2/4𝜋. We determine the effect of the HTL resummation on the bound-state formation and dissociation rates of heavy dark fermions in presence of a hot (with temperature 𝑇), weakly coupled (𝑇≫𝑔𝑇) dark plasma, under the assumption that 𝑚≫𝑚𝛼≫𝑇. Our analysis is based on Non-Relativistic Effective Field Theory (NREFT) to address the dark matter threshold dynamics and on Thermal Field Theory to address the thermal scales. We obtain and solve coupled Boltzmann equations and show how our results affect the evolution of the dark matter density in the Early Universe. Working with this simplified model of the dark sector, we show that the effect of HTL resummation on the bound-state formation and thermal relic abundance is non-negligible (and of the same order as the NLO fixed order correction), which indicates the importance of further studies in more realistic scenarios. This, to our knowledge, is the first study of the impact of the scale 𝑚𝐷 on dark matter scattering and bound states formation in a systematic framework.

Speaker: Andrii Dashko (DESY Theory)

QMDM-2024.pdf

17:35 Indirect detection of dark matter with (pseudo)-scalar interactions

Indirect detection is one of the most powerful methods to search for annihilating dark matter. In this work, we investigate the impact of non-perturbative effects in the indirect detection of dark matter. For this purpose we utilize a minimal model consisting of a fermionic dark matter candidate in the TeV mass range that interacts via scalar- and pseudo-scalar interactions with a massive scalar mediator mixing with the Higgs. The scalar interaction induces an attractive Yukawa potential between dark matter particles, such that annihilations are Sommerfeld enhanced, and bound states can form. These non-perturbative effects are systematically dealt with (potential) non-relativistic effective field theories and we derive the relevant cross sections for dark matter. We discuss their impact on the relic density and indirect detection. Annihilations in dwarf galaxies and the Galactic Center require special care and we derive generalized 𝐽-factors for these objects that account for the non-trivial velocity dependence of the cross sections in our model. We use limits on the gamma-ray flux based on Fermi-LAT observations and limits on the rate of exotic energy injection from Planck to derive bounds on the parameter space of the model. Finally, we estimate the impact that future limits from the Cherenkov Telescope Array are expected to have on the model.

Speaker: Julian Bollig (Albert-Ludwigs-Universität Freiburg)

QMDM_2024.pdf

17:55 → 18:40 Round Table - Monday

Chair: Peter Vander Griend,
Panel: Kalliopi Petraki, Matthew Baumgart, Jan Heisig, Benoît Assi

Topics:
1. shared tools between quarkonia and dark matter communities
(a) How are relativistic quantum field theoretic, nonrelativistic effective field theoretic and quantum mechanical treatments used in the quarkonium and dark matter (DM) communities? What are the advantages of each approach and what results can be obtained?
(b) How are numerics handled in the two communities? Are there methods in common
or codes that can be shared?
2. unitarity
(a) What bounds does unitarity place on the DM parameter space?
(b) What are the phenomenological implications of the partial-wave unitarity limit for multi-TeV dark matter?
3. finite temperature
(a) What physical impact do finite temperature T and finite chemical potential µ effects have in quarkonium and DM physics?
(b) What is the size of finite temperature corrections for DM freeze out?
(c) How important is the scale of the Debye mass mD and how much has this been considered up to now?

Speakers: Benoit Assi (U Hamburg), Jan Heisig (RWTH Aachen University), Kallia Petraki (ENS and Sorbonne University), Matthew Baumgart (Arizona State University), Peter Vander Griend (University of Kentucky and Fermilab)

round_table_1.pdf

Tuesday 19 March

09:00 → 10:45 Tuesday - Session 1

09:00 Nonperturbative regime: quarkonium

I review how strongly coupled potential nonrelativistic QCD (pNRQCD) and lattice
can describe quarkonium in the confinement region. A new effective field theory called Born Effective Field Theory (BOEFT) is able also to describe the new XYZ exotics discovered in the sector with two heavy quarks. I discuss the implications
of these findings for nonperturbative scenarios of DM.

Speaker: Nora Brambilla (Physik Department, TU Munich)

dark242.pdf

09:35 Strong cosmological phase transitions through the EFT lens

To describe cosmological phase transitions perturbatively, scale hierarchies are required. At finite temperature such a hierarchy is provided naturally for gauge theories. If this hierarchy is not accounted for, uncertainties of phase transition thermodynamic parameters can be large due to infrared sensitivity and slow perturbative convergence faced by scalar bosons.

To reliably describe the phase transition thermodynamics, one can then use this hierarchy and construct a three-dimensional effective theory that systematically includes thermal resummations to all orders. Focusing on generic scalar extensions beyond the Standard Model, I determine their dimensionally reduced theory and the corresponding effective potential using the in-house software package DRalgo [1]. Finally, I present a minimal approach [2] that reconciles both gauge invariance and thermal resummation suitable for precision computations of the thermodynamic parameters of cosmological first-order phase transitions. Finally, I will address the impact of such computational diligence at the level of GW signals.

[1] A. Ekstedt, P. Schicho, and T. V. I. Tenkanen, DRalgo: A package for effective field theory approach for thermal phase transitions, Comput. Phys. Commun. 288, 108725 (2023), [2205.08815].
[2] P. Schicho, T. V. I. Tenkanen, and G. White, Combining thermal resummation and gauge invariance for electroweak phase transition, JHEP 11, 047 (2022), [2203.04284].

Speaker: Philipp Schicho (Goethe University Frankfurt)

schicho.qmdm.pdf

10:10 Quarkonia in lattice field theory at finite temperature

Quarkonia are versatile probes to study the hot primordial nuclear matter. Their dynamics are usually described through models based on resummed perturbative QCD, AdS, and effective field theories. It is not immediately obvious to which extent these models can describe the strongly coupled media most relevant to phenomenology. The lattice provides nonperturbative input and constraints to such models.
In-medium bottomonia and the complex static quark-antiquark potential are key quantities where lattice gauge theory has recently achieved significant progress with major impact for heavy-ion phenomenology. I review the recent lattice results, relate them to phenomenology, and close with an outlook.

Speaker: Johannes Heinrich Weber (Technische Universität München)

qmdm_2024_weber.pdf

10:45 → 11:15 Coffee Break

11:15 → 12:30 Tuesday - Session 2

11:15 transport coefficients in medium on the lattice

Heavy probes are an excellent tool to study the quark gluon plasma formed at the heavy ion collision experiments. The lattice results of the transport coefficients provide an important input to phenomenological models explaining these experiments. Especially interesting transport property studied a lot in the recent years, is the diffusion of heavy quarks and quarkonium. Such diffusion coefficients provide vital information in explaining the strong suppression of the nuclear modification factor $R_{AA}$. In this talk, I will discuss the recent lattice progress on the in medium transport coefficients on the lattice, mainly the diffusion coefficients.

Speaker: Viljami Leino (TUM)

QMDM_Leino.pdf

11:40 Insights from holography on the transport of heavy particle pairs in strongly coupled non-Abelian plasmas

Suppression of open heavy flavors and quarkonia in heavy-ion collisions is among the most informative probes of the quark-gluon plasma (QGP). Interpreting the full wealth of data obtained from the collision events requires a precise understanding of the evolution of heavy quarks and quarkonia as they propagate through the nearly thermal and strongly coupled plasma. Only in the past few years, systematic theoretical studies of quarkonium time evolution in the QGP have been carried out in the regime where the temperature of the QGP is much smaller than the inverse of quarkonium size. Similarly, an analog theoretical treatment is required for heavy dark matter (DM) particle candidates in the early universe, which may also have undergone processes of bound-state formation and dissociation in co-annihilation scenarios that can affect how the present-day DM abundance is explained in terms of the underlying theory.

Such calculations require the evaluation of a gauge-invariant correlator of chromoelectric fields dressed with Wilson lines, which is similar to, but different from, the correlation used to define the well-known heavy quark diffusion coefficient. In this talk, we will describe its calculation at weak coupling in QCD up to next-to-leading order and at strong coupling in $\mathcal{N}=4$ SYM using the AdS/CFT correspondence. Furthermore, we will discuss the necessary setup to evaluate the quarkonium transport coefficients from lattice QCD. Finally, we will discuss the phenomenological implications that can be extracted from this correlator, with emphasis on the implications of the novel $\mathcal{N}=4$ SYM results at strong coupling.

Speaker: Bruno Scheihing Hitschfeld (Massachusetts Institute of Technology)

qmdm-Scheihing-Hitschfeld.pdf

12:05 Connecting the baryons to the dark matter of the Universe

The existence of dark matter in our Universe and the existence of an asymmetry between nucleons and antinucleons are two of the most solid evidences for physics beyond the Standard Model. Many mechanisms have been proposed to explain these two phenomena. On the other hand, these mechanisms typically involve different particles and different energy scales, therefore the observed similarity between the dark matter abundance and the nucleon abundance is merely coincidental. In this talk we will propose a scenario that can accommodate the observed nucleon-antinucleon asymmetry without fulfilling the Sakharov conditions. Further, our scenario predicts a stable dark matter candidate without invoking new ad-hoc symmetries, and with an abundance which is in the ballpark of the observed value.

Speaker: Alejandro Ibarra (TUM)

Ibarra.pdf

12:30 → 13:45 Lunch Break

13:45 → 15:45 Tuesday - Session 3

13:45 Composite dark matter from confining gauge theories

TBC
by: Michele Redi

Speaker: Michele Redi

7_Redi_Munich 24.pdf

14:20 Heavy Thermal Dark Matter

I will give the general properties of freezeout of a thermal relic.
This will be used to give an approximate perturbative unitarity bound
on the dark matter mass for an arbitrary thermal freezeout process. I
will show that within a standard cosmology it is possible to have
thermal dark matter freezeout via perturbative processes well above
the WIMP unitarity bound of 100 TeV. For dark matter above this mass,
there are nearly degenerate states with the dark matter and the dark
matter is generically metastable. I will give examples of freezeout of
a thermal relic that allow for dark matter masses up to the Planck
scale.

Speaker: Eric Kuflik

EricKuflik.key

EricKuflikQMDM.pdf

14:45 Exploring the Gravitational Wave Universe with PTAs: where we are and where we are going.

By tracking the arrival times of radio pulses from a collection of pulsars in the Milky Way, several pulsar timing array collaborations have found evidence for a background of gravitational waves permeating our galaxy. In this talk, I will present this evidence, review possible cosmological interpretations of the signal, and discuss ways to discriminate between the signals emitted by these cosmological sources and the one produced by black hole binaries.

Speaker: Andrea Mitridate (DESY)

mitridate_qmdm.pdf

15:15 Theoretical uncertainties from thermal field theory and finite temperature field theory

A reliable calculation of gravitational waves from a first order phase transition requires an accurate treatment of the thermal evolution of the effective potential. One loop corrections to the thermal potential are well known to miss numerically important contributions leading to theoretical uncertainties that are orders of magnitude in size for common treatments of phase transitions. Dimensional reduction naturally organizes perturbation theory into powers of the coupling constant ensuring that one always is considering contributions to the potential in order of largest to smallest. At next to leading order, dimensional reduction reduces the uncertainties to the percent level. I will also discuss gauge the controversies around gauge invariance and avenues for handling very strong transitions where the high temperature expansion breaks down.

Speaker: Graham White

10 quarkonia_tum_GW.key

15:45 → 16:15 Coffee Break

16:15 → 16:40 Tuesday - Session 4

16:15 Scattering of Dark Pions in an Sp(4) gauge theory

We consider strongly interacting dark matter candidates as composite states of Nf=2 fermions charged under a dark Sp(4) gauge group in the fundamental representation. We calculate correlation functions of two pseudo-Nambu-Goldstone-bosons on the lattice and present first results of the scattering phase shift in the isospin-2 channel. We calculate the self-interaction cross-section in the s-channel and get constraints for the dark matter particle mass by comparison to astrophysical constraints.

Speaker: Yannick Dengler (University of Graz)

Talk_QMDM24_YD.pdf

16:40 → 17:25 Round Table - Tuesday

Chair:
N. Brambilla
Panel:
J. Ghiglieri, E. Kuflik, E. Morgante, M. Redi, B. Scheihing J. Weber, G. White

Speakers: Bruno Scheihing Hitschfeld (Massachusetts Institute of Technology), Enrico Morgante (U. Trieste & INFN), Eric Kuflik, Graham White, Johannes Heinrich Weber (Technische Universität München), Michele Redi, Nora Brambilla (Physik Department, TU Munich)

QMDM_roundtable-Tuesday.pdf

18:00 → 20:00 Poster Session

Wednesday 20 March

08:55 → 10:35 Wednesday - Session 1

09:00 Quarkonium transport in quark-gluon plasma: Open quantum system approach

I will review recent developments of applying the open quantum system framework to understand quarkonium dynamics inside the quark-gluon plasma. I will discuss three temperature regions that are relevant to the current relativistic heavy ion collision experiments. I will focus on how medium properties are encoded in the transport equations for each temperature region and discuss how to calculate them nonperturbatively.

Speaker: Xiaojun Yao (University of Washington)

oqs for quarkonium.pdf

09:35 Dark Matter Production at Finite Temperature

//

Speaker: Julia Harz (Johannes Gutenberg University of Mainz)

QuarkoniumWorkshopMunich2024.pdf

10:10 Transport of Dark Matter pairs at finite T

//

Speaker: Tobias Binder (TUM)

TB_QMDM2024.pdf

10:35 → 11:05 Coffee Break

11:05 → 12:30 Wednesday - Session 2

11:05 Master and Lindblad equation for quarkonium

In this talk, I will review the status and recent advances in the description of quarkonium suppression using the formalism of open quantum systems.

Speaker: Miguel Ángel Escobedo Espinosa (University of Barcelona)

qmdm2024.pdf

11:40 Suppression and Regeneration of Bottomium in Heavy Ion Collisions from Open Quantum Systems and Effective Field Theories

For decades, bound states of heavy quarks have served as ideal experimental and theoretical probes of the medium formed in heavy ion collisions. Specifically, suppression of heavy quarkonium states in heavy ion relative to proton-proton collisions was postulated as a strong signal of the formation of a deconfined quark gluon plasma (QGP). More recently, the use of effective field theories (EFTs) and the formalism of open quantum systems (OQS) has allowed for great advances in first-principles descriptions of in-medium heavy quarkonium. Using EFTs, one can systematically exploit the hierarchies of scale of the combined system to arrive at an effective description valid in a particular regime while the OQS formalism enables a quantum description of a system evolving coupled to and out of equilibrium with an environment. In this talk, we present results obtained by solving the Lindblad equation derived using the EFT potential nonrelativistic QCD and the OQS formalism which describes the dissociation and regeneration of Υ(1S), Υ(2S) and Υ(3S) states propagating in a strongly coupled QGP. We emphasize our good agreement with experimental data from the ALICE, ATLAS and CMS experiments.

Speaker: Peter Vander Griend (University of Kentucky and Fermilab)

vander_griend_qmdm.pdf

12:05 Real-time Dynamics of the Schwinger Model as an Open Quantum System with Neural Network Quantum States

Ab-initio simulations of multiple heavy quarks propagating in a Quark-Gluon Plasma are computationally difficult to perform due to the large dimension of the space of density matrices. Neural Network Quantum States offer a promising approach to overcoming this numerical difficulty by variationally parametrising quantum states with parameters of a Neural Network. In this talk, I present proof of principle demonstrations of these methods in a QCD-like theory, by solving the Lindblad master equation in the 1+1d lattice Schwinger Model as an Open Quantum System. Neural Network quantum states enable the study of in-medium dynamics on large lattice volumes, where multiple-string interactions and their effects on string-breaking and recombination phenomena can be studied. Thermal properties of the system at equilibrium can also be probed with these methods by variationally constructing the stable state of the Lindblad master equation. Scaling of this approach with system size is presented, and numerical demonstrations on up to 32 spatial lattice sites and with up to 3 interacting strings are presented.

Speaker: Joshua Lin (MIT)

main.pdf

12:30 → 13:50 Lunch Break

13:50 → 15:20 Wednesday - Session 3

13:50 Phenomenological Impact of Sommerfeld Effect and Bound State Formation in Coannihilating Simplified Dark Matter Models

The existence of a dark matter (DM) model with a rich dark sector could be the reason why WIMP DM has evaded its detection so far. For instance, colored co-annihilation naturally leads to the prediction of heavier DM masses. Moreover, non-perturbative effects such as Sommerfeld corrections and bound state formation must be considered to accurately predict the DM relic abundance. In the context of simplified t-channel DM models with a colored mediator, I will show the importance of correctly considering these non-perturbative effects for accurately inferring the viable model parameters. In particular, I will stress how parts of the parameter space thought to be excluded by direct detection experiments and LHC searches remain still viable. Additionally, I illustrate that long-lived particle searches and searches for bound-state resonances at the LHC can play a crucial role in probing such a model and how future direct detection experiments will be able to close almost all of the remaining windows for DM produced via the freeze-out mechanism, making it a highly-testable scenario.

Speaker: Emanuele Copello (JGU Mainz)

Copello_QMDM24.pdf

14:10 A framework for Sommerfeld effect and bound state formation of colored mediators in dark matter studies

Simplified t-channel dark matter models serve as a versatile and well-motivated framework for rich
dark sectors that are widely studied by ongoing experimental and theoretical efforts. In this work,
we investigate the impact of non-perturbative effects on the dark matter relic abundance for two
representative models of this kind of models, focusing on regions of parameter space where coannihilations of colored mediators are important.
In such scenarios, it is well known that the Sommerfeld enhancement and bound state formation
processes can significantly alter the predictions for the model parameters of the dark matter
candidate.
Besides including the effects stated above, we take into account the effects of excited states beyond the ground state. We will present constraints on models with fermionic and scalar mediators,
highlighting the differences and common features of these two.
Moreover, we introduce code that seamlessly integrates with micrOMEGAs 6.0, which can be
easily adapted by the user for different models.

Speaker: Martin Napetschnig (Technical University of Munich)

Napetschnig_tchannel_BSF.pdf

14:30 Excited bound states in dark matter genesis beyond the WIMP paradigm

The nature of dark matter in our Universe remains one of the most compelling inquiries in fundamental physics today. While weakly interacting massive particles (WIMPs) have been the primary candidates for dark matter in the past decades, alternative explanations have gained more and more attention due to a growing number of null-results in experimental WIMP searches. Here, we go beyond the WIMP paradigm by considering very weakly dark matter couplings mediated by a t-channel mediator particle charged under SU(3)_c. In the early Universe, they can form bound states which largely alter the freeze-out dynamics. Interestingly, due to the small dark matter couplings, the freeze-out process is prolonged towards smaller temperatures, rendering higher excitations to become increasingly important due to their larger bound state formation cross section and multiplicity. We present an efficient way to include a large number of excited states (up to around a million) and investigate the scenario's phenomenology. The model allows for dark matter genesis via so-called conversion-driven freeze-out or superWIMP production. In the former mechanism, semi-efficient conversions between the colored mediator and dark matter initiate thermal freeze-out. In the latter scenario, late decays of the mediator particle into dark matter produce a non-thermal abundance. In both scenarios, we find that bound state effects play a key role in the relic density computation affecting the result by up to an order of magnitude with important phenomenological implications. The scenarios can be tested at the LHC through searches for long-lived particles as well as cosmological probes of the small scale structure, respectively.

Speaker: Jan Heisig (RWTH Aachen University)

Heisig_QMDM2024.pdf

14:55 Dark Matter from SU(N) Confinement

Confinement in $SU(N_{\rm DC})$ Yang-Mills theories is known to proceed through first-order phase transition. The wall velocity is bounded by $v_w \leq \mathcal{O}(10^{-6})$ due to the needed time for the substantial latent heat released during the phase transition to dissipate through Hubble expansion. Quarks much heavier than the confinement scale can be introduced without changing the confinement dynamics. After they freeze-out, heavy quarks are squeezed into pockets of the deconfined phase until they completely annihilate with anti-quarks. We calculate the dark baryon abundance surviving annihilation, due to bound-state formation occurring both in the bulk and - for the first time - at the boundary. We find that dark baryons can be dark matter with a mass up to $10^3~\rm TeV$. We study indirect and direct detection, CMB and BBN probes, assuming portals to Higgs and neutrinos.

Speaker: Dr Di Liu (CNRS-LAPTh)

DL_QMDM_0324.pdf

15:20 → 15:50 Coffee Break

15:50 → 17:40 Wednesday - Session 4

15:50 Production of Feebly Interacting Particles at Finite Temperature

Models of feebly-interacting Dark Matter (DM) have gained popularity due to the non-observation of DM in direct detection experiments. Unlike DM freeze-out, which occurs when the dark sector particles are non-relativistic, feebly-interacting DM is primarily produced at temperatures corresponding to the heaviest mass scale involved in the production process. Consequently, incorporating finite temperature corrections becomes essential for an accurate prediction of the relic density. However, current calculations are often performed at either zero temperature or rely on thermal masses to regulate infrared divergences. In our study, we utilize the Closed-Time-Path (CTP) formalism to compute the production rate of feebly-interacting DM associated with a gauge charged parent. We compare our results with the aforementioned approaches such as the insertion of thermal masses, zero temperature calculations and well established approximation schemes as the Hard-Thermal-Loop approximation. Furthermore, we discuss the applicability and feasibility of these different approaches for phenomenological studies.

Speaker: Mathias Becker (JGU Mainz)

TUM24_FeebleParticles.pdf

16:15 Thermal effects in freeze-in DM production

In this talk I will consider a DM model with a new sector comprising of a Dark Matter fermion and a colored, heavier scalar, Yukawa-coupled to a Standard Model quark. In this model the DM fermion is produced both from freeze in and from the later decays of the frozen-out scalars. I will discuss how thermal effects such as the emergence of collectivity, of screening and of multiple interactions can be accounted for. I will show how they can significantly alter the standard expectation, namely that freeze-in production is dominated by temperatures of the order of the mass of the DM particle.
I will also discuss how the rate in the ultrarelativistic regime can be smoothly connected to the relativistic one

Speaker: Jacopo Ghiglieri (SUBATECH, Nantes)

ghiglieri_TUM24.pdf

16:40 Dark matter annihilation with full collision terms

The standard approach of calculating the relic density of thermally produced dark matter based on the assumption of kinetic equilibrium is known to fail for forbidden dark matter models since only the high momentum tail of the dark matter phase space distribution function contributes significantly to dark matter annihilations, resulting in early kinetic decoupling of dark matter. Furthermore, it is known that the computationally less expensive Fokker-Planck approximation for the collision term describing elastic scattering processes between non-relativistic dark matter particles and the Standard Model thermal bath breaks down if both scattering partners are close in mass. This, however, is the defining feature of the forbidden dark matter paradigm. We therefore include the full elastic collision term in the full momentum-dependent Boltzmann equation as well as in a set of fluid equations that couple the evolution of the number density and dark matter temperature for a simplified model featuring forbidden dark matter annihilations into muon or tau leptons through a scalar mediator. The overall phenomenological outcome is that the updated relic density calculation results in a significant reduction of the experimentally allowed parameter space compared to the traditional approach, which solves only for the abundance.

Speaker: Luca Wiggering (University of Münster)

LW_QMDM_2024.pdf

17:00 Minimal decaying dark matter: from cosmological tensions to neutrino signatures

The invisible decay of cold dark matter into a slightly lighter dark sector particle on cosmological time-scales has been proposed as a solution to the $S_8$ tension. In this talk, I want to present a possible embedding of this scenario within a particle physics framework and discuss its phenomenology. The model is set up of a minimal dark matter decay, where the dark sector contains two singlet fermions $N_{1,2}$, quasi-degenerate in mass, and carrying lepton number so that the heaviest state ($N_2$) decays into the lightest ($N_1$) and two neutrinos via a higher-dimensional operator $N_2 \to N_1\nu\nu$. Due to the present symmetries and small phase space, the decays into photons or charged leptons are strongly suppressed and thus its stringent constraints from indirect dark matter searches can be avoided. Additionally, complementary constraints on the model parameters arise from neutrino detectors, freeze-in dark matter production, collider experiments and blazar observations. Together, these single out dark matter masses below ∼ 1 GeV where constraints still allow for model parameters addressing the $S_8$ tension. Signals of dark matter in this parameter space of interest could be detected by the upcoming JUNO neutrino observatory.

Speaker: Lea Fuß (Technical University Munich)

Talk_QMDM_2024.pdf

17:20 The GUT way for composite dark matter

Speaker: Sonali Verma

gut_munich_2024.pdf

17:40 → 18:25 Round Table 3

Chair: Xiaojun Yao, Tobias Binder
Panel Member: Nora Brambilla, Gramos Qerimi, Mathias Garny, Viljami Leino, Julia Harz, Ayuki Kamada

Keywords: quarkonium diffusion, dark matter momentum transfer rate, complex thermal width, matching different regimes in OQS approach

QMDM_answerQuestion2.pdf

QMDM_roundtable3.pdf

Thursday 21 March

09:00 → 10:30 Thursday - Session 1

09:00 Probing dark sectors with gravitational waves

Gravitational waves provide a new window into the early Universe, and thus a new way of probing the dynamics of dark sectors. I will provide an overview of primordial gravitational wave sources, highlight what we have learned recently and speculate about possible future insights.

Speaker: Pedro Schwaller

QmDM_2024_GWs_darksector.pdf

09:35 Future 21cm Constraints on DM Energy Injection

TBA

Speaker: Laura Lopez Honorez (ULB)

24-QMmeetsDM-LLH.pdf

10:00 Latest results on Beyond the Standard Model from ATLAS

The second period of data taking at the Large Hadron Collider has provided a large dataset of proton-proton collisions that is unprecedented in terms of its centre-of-mass energy of 13 TeV and integrated luminosity of almost 140/fb. These data constitute a formidable laboratory for the search for new particles beyond those predicted by the Standard Model. The most recent results of the ATLAS Collaboration will be presented. In absence of significant deviation from the Standard Model predictions, interpretations of the results in terms of exclusion limits in different models of new phenomena will be discussed.

Speaker: Maria Pilar Casado

QMDM24_casado.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Thursday - Session 2

11:00 Advancements in Direct Dark Matter Detection with XENONnT

Direct experimental evidences of dark matter have been searched exploiting several technologies.
Among these, liquid xenon TPCs have demonstrated extraordinary sensitivity for WIMP dark matter searches.
Moreover, the XENONnT experiment has also recently demonstrated to reach an unprecedented level of WIMP sensitivity and electronic-recoil background, unlocking the possibility of exploring several other dark matter candidates.
This talk will focus on the XENONnT latest results.

Speaker: Cecilia Ferrari

Advancements in Direct Dark Matter Detection with XENONnT.pdf

11:30 Indirect Dark Matter Searches in Dwarf Spheroidal Galaxies

One of the most pressing questions for modern physics is the nature of dark matter (DM). Several efforts have been made to model this elusive kind of matter since the largest fraction of DM cannot consist of any of the known particles of the Standard Model (SM) according to the Lambda-CDM model. Among the candidates proposed to explain the nature of DM, weakly interacting massive particles (WIMPs) are one of the preferred ones. WIMPs could be detected indirectly by observing the secondary products of their annihilation into SM particles. Extensive observing campaigns with gamma-ray telescopes and neutrino detectors have been carried out over the past decades in presumed DM-dominated regions such as dwarf spheroidal galaxies (dSphs). In the absence of a signal, constraining limits on the DM self-annihilation cross-section have been set. In this contribution, we present a joint likelihood analysis combining dSph observations taken with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS to maximize the sensitivity of indirect DM searches. The observed limits on the thermally-average velocity-weighted annihilation cross-section of our combined analysis reach $\sim 3 \times 10^{-25}$ cm$^3$s$^{-1}$ in the $\tau^+\tau^-$ annihilation channel for a 2 TeV DM particle mass.

Speaker: Tjark Miener (UniGE - DPNC)

20240321_DMSearch_TjarkMiener.key

20240321_DMSearch_TjarkMiener.pdf

12:00 The search for dark matter with the Cherenkov Telescope Array

The flux of high-energy gamma rays provides crucial information for constraining the properties of particle dark matter candidates, such as Weakly Interacting Massive Particles (WIMPs) or Axion-Like Particles (ALPs). Slowly but steadily entering the construction phase at its sites in both the northern and southern hemispheres, the Cherenkov Telescope Array (CTA) is set out to explore the sky in the 20 GeV - 300 TeV energy range. With improved energy and angular resolutions, as well as a significantly larger effective area compared to the current generation of Cherenkov telescopes, the CTA is expected to venture into unexplored terrain in the parameter space of WIMPs, ALPs, and other particle dark matter models. The CTA will enable us to search for dark matter signatures across the entire gamma-ray sky, including targets such as the Milky Way's Galactic centre, dwarf spheroidal galaxies, the Large Magellanic Cloud, and extragalactic objects. In this talk, I provide an overview of the CTA's capabilities as a dark matter discovery instrument, focusing on prospects for the search for TeV-scale WIMP dark matter and ALPs.

Speaker: Christopher Eckner (University of Nova Gorica, Center for Astrophysics and Cosmology)

QMDM_2024_TUM_21-03-24_Eckner.pdf

12:30 → 13:50 Lunch Break

13:50 → 15:35 Thursday - Session 3

13:50 Gravitational waves from cosmological phase transitions

In many extensions of the Standard Model, the universe underwent one or several first order phase transitions. Such phase transitions proceed via the formation and collision of bubbles. The bubble collisions can source a stochastic gravitational wave background signal. In the case of the electroweak phase transition, the characteristic frequency would fall right in the sensitivity band of LISA. We can thus use data from gravitational wave experiments to probe physics beyond the standard model. In this talk, I will give an overview of the relevant contributions to the gravitational wave signal, and then focus on the contribution to the gravitational wave signal from sound waves.

Predictions of the gravitational wave spectrum typically rely on hydrodynamic lattice simulations of the scalar-plasma system. Hydrodynamic solutions of a single expanding bubble provide a bridge between the particle physics model and the hydrodynamic lattice simulation. Two relevant quantities in this computation are the bubble expansion velocity and the kinetic energy budget. I will discuss the computation of the bubble wall velocity, and present recent progress in the computation of this quantity, obtained in the limiting cases of local thermal equilibrium and a large enthalpy jump between the two phases.

Speaker: Jorinde van de Vis (Leiden University)

GWsJvdVis.pdf

14:25 Upper Bound on Thermal Gravitational Wave Backgrounds from Hidden Sectors

Hot viscous plasmas unavoidably emit a gravitational wave background, similar to the electromagnetic black body radiation. We study the contribution from hidden particles to the diffuse background emitted by the primordial plasma in the early universe. While this contribution can easily dominate over that from Standard Model particles, we find that both are capped by a generic upper bound that makes them difficult to detect with interferometers in the foreseeable future. However, resonant cavity experiments could potentially observe backgrounds that saturate the upper bound. We illustrate our results for axions and heavy neutral leptons. Finally, our results suggest that previous works overestimated the gravitational wave background from particle decays out of thermal equilibrium.

based on:
https://arxiv.org/abs/2312.13855

Speaker: Yannis Georis

YannisGeoris_quarkonia.pdf

15:00 QCD theta-parameter in infinite and finite volumes

Taking Euclidean space as an analytic continuation of Minkowski
spacetime, topological sectors in QCD follow from the principle of
finite action (or fluctuations about finite action configurations).
Thus, the limit of spacetime volume must be taken before summing over
integer topological sectors, leaving the correlation functions
parity-even and theta immaterial. It is now of interest to see what
happens in finite spacetime volumes. As time is compactified, there is
no meaningful analytic continuation of the system to real time but of
course, there is the interpretation in terms of the trace of the
canonical density operator (which is the basis of lattice simulations).
To compute the trace, the theory must be canonically quantized which
requires a normalizable inner product. The latter requires gauge fixing.
In particular, redundant configuration related by large gauge
configurations must not be summed over. The only path to consistently
constrain the wave functionals then leads to a system where parity and
the Hamiltonian commute.

arXiv:2403.00747 [hep-th]

Speaker: Björn Garbrecht (TUM)

Quarkonia24.pdf

15:35 → 16:05 Coffee Break

16:05 → 17:55 Thursday - Session 4

16:05 Exploring new physics with pulsar timing arrays

Earlier this year several pulsar timing arrays unveiled the first detection of the stochastic gravitational wave background at nano-Hertz frequencies. The background could potentially arise from myriad merging black holes or – arguably more exciting – an event in the early cosmos. In this talk, I will discuss two recent works on the origin of the new signal: First, I will show under which conditions dark sector phase transitions can serve as an explanation compatible with constraints from precision cosmology. In a second part I will explore how merging clusters of primordial black holes present a promising complementary explanation. I conclude with a comment on the question of the likelihood of a new physics explanation in a Bayesian framework.

Speaker: Carlo Tasillo (DESY Hamburg)

2024_03_21_Munich.pdf

16:25 Simulation and Indirect Detection of Dark Glueball Showers

Parton showers are part and parcel of particle phenomenology, but what in the case of a confining dark sector with no light quarks below the confinement scale? The only available hadronic states are dark glueballs, composite dark gluon states. To date, there have been very few quantitative studies of dark shower signatures with dark glueball final states, despite the fact they commonly appear in motivated BSM theories such as neutral naturalness, and are prominent LLP candidates. This is due to the fact that commonly used hadronisation models, such as the Lund model, are no longer valid. We found that significant progress can be made despite the non-perturbative uncertainties. In this talk I will outline a method of simulating the formation of dark glueballs from a perturbative dark gluon shower, and how we handle the hadronisation process. This simulation has allowed us to study a variety of dark glueball phenomena quantitatively for the first time, including the indirect detection of DM annihilating into dark glueballs that then decay into the SM.

Speaker: Caleb Gemmell (University of Toronto)

gemmell_QMDM.pdf

16:45 Gravitational waves from non-Abelian dark sectors coupled to inflation

Taking axion inflation as an example, we study the evolution of a non-Abelian dark sector coupled to inflaton for different choices of the confinement scale. For confinement scales just a few orders of magnitude below the Planck scale, gravitational wave signal generated by fluctuations in the thermal plasma may become relevant. Another possible source of gravitational waves is the confinement phase transition; however, this signal might be strongly suppressed due to the presence of an early matter-dominated era. This talk is based on collaboration with Simona Procacci and Mikko Laine (https://arxiv.org/pdf/2303.17973 and https://arxiv.org/pdf/2311.03718).

Speaker: Helena Kolesova (University of Stavanger)

Munich_Kolesova.pdf

17:10 Gravitational waves from confinement in improved holographic QCD

We analyze the phase transition in improved holographic QCD and obtain an estimate of the gravitational wave signal emitted in the confinement transition of a pure SU(N) Yang-Mills dark sector.

Speaker: Enrico Morgante (U. Trieste)

Morgante_TUM.pdf

17:35 The Higgsless Simulations of First-order Phase Transition

Since the LIGO-Virgo-KAGRA gravitational wave (GW) detection from binary systems, GWs have become one of the most promising probes of cosmology and fundamental physics. The GW agenda is complemented by Pulsar Timing Arrays (PTA) probing the nHz frequency band, such as the European PTA (EPTA) and NANOGrav, both recently reporting a 3sigma evidence for a GW background. A next major step in that agenda is the Laser Interferometer Space Antenna (LISA), commissioned by ESA with NASA as a junior partner, and expected to be launched in the next decade. The detection of a stochastic GW background (SGWB) from interferometers or PTAs would offer an exciting look into the very early Universe, revealing fundamental physics on cosmological scales never probed before. This talk will focus on first-order phase transitions (PTs), one of the main mechanisms capable of sourcing SGWBs in the early Universe. I will present the Higgsless approach to simulate the plasma dynamics and to predict the stochastic GW spectrum from PTs. I will explain how the Higgsless simulations can produce fully nonlinear results and extend the current predictions to strong PTs, one of the most exciting scenarios to be explored by LISA and PTAs.

Speaker: Henrique Rubira (TUM)

Quarkonia_GWsim_24_03_21.pdf

17:55 → 18:40 Round Table - Thursday

Chairs: Marco Drewes, Jorinde van de Vis
Panel Members: Mathias Becker, Maria Pilar Casado, Simona Procacci, Henrique Rubia, Carlo Tasillo

Speakers: Carlo Tasillo (DESY Hamburg), Henrique Rubira (TUM), Jorinde van de Vis (Leiden University), Marco Drewes (TUM), Maria Pilar Casado Lechuga (UAB/IFAE), Mathias Becker (JGU Mainz), Simona Procacci (U. Geneva)

Discussion Session 4.pdf

Friday 22 March

09:00 → 10:40 Friday - Session 1

09:00 Hydrodynamic backreaction forces in expanding bubbles

In first-order cosmological phase transitions, it has been commonly accepted that subluminal bubble expansion requires out-of-equilibrium interactions with the plasma which are captured by friction terms in the equations of motion for the scalar field. This has been disputed in works pointing out subluminal velocities in local equilibrium arising either from hydrodynamic effects in deflagrations or from the entropy change across the bubble wall in general situations. In this talk it will be argued that both effects are related and can be understood from the conservation of the entropy of the degrees of freedom in local equilibrium. Despite the lack of an explicit friction term in the equation of motion for the scalar field undergoing the phase transition, the friction effect arises from temperature gradients across the bubble wall, which are enforced by the background field dependence of the conserved entropy current in the plasma. This can lead to subluminal speeds for both deflagrations and detonations. The effects can be accounted for by simply imposing local conservation of stress-energy and including field-dependent thermal contributions to the effective potential.

Speaker: Carlos Tamarit

tamarit_hydrodynamic_backreaction.pdf

09:30 Simple computations for bubble wall velocities

The bubble wall velocity is a critical parameter for estimating the gravitational wave signal coming the phase transitions in the early universe. The most precise computations are usually quite involved and require time, which can make then inconvenient for the large use to BSM models. In this talk, I will present two limits, the local thermal equilibrium limit and the relativistic limit, in which this computation can be made almost straightforward. I will discuss applications and limitations of the methods.

Speaker: Miguel Vanvlasselaer (VUB)

Presentation_QMDM_Miguel_Vanvlasselaer.pdf

09:55 Gravitational waves from the QCD chiral phase transition in a supercooled Universe

Theories beyond the Standard Model (BSM) with classical scale invariance predict an intriguing thermal history of the early Universe. Due to the absence of dimensionful terms at tree level in these models, the electroweak phase transition (EWPT) can be significantly delayed, inducing a period of thermal inflation supercooling the Universe. As the SM quarks may remain massless at the QCD scale, the exit from this supercooled state can be triggered via a strong, first-order QCD chiral phase transition. I will discuss how the QCD phase transition can be studied with effective Polyakov loop models, with a particular focus on the impact of thermal inflation on the strongly coupled dynamics. Finally, I will present the expected gravitational wave (GW) spectra which are considerably enhanced in a supercooled Universe. This enhancement implies promising observational prospects at future GW detectors.

Speaker: Daniel Schmitt (Goethe University, Frankfurt)

240322_QMDM_Munich.pdf

10:15 Probing dark sectors with atomic spectroscopy

The past two decades have been characterised by extraordinary accomplishments in the control of matter and light. This has opened up new avenues for atomic, molecular and optical physics including novel tests of physics beyond the Standard Model. The combined use of effective field theories, precision computations and highly accurate experimental data makes spectroscopy a competent and reliable testing ground for dark sectors in the keV-MeV range. We present the EFT framework to carry out such study and propose two main phenomenological applications: purely leptonic systems such as muonium and semileptonic systems, where the newly attained proton radius has pushed the theoretical precision of hydrogen and muonic hydrogen spectroscopy.

Speaker: Clara Peset (Complutense University of Madrid)

SpectroscopyEFT_Peset_QMDM.pdf

10:40 → 11:10 Coffee Break

11:10 → 13:30 Friday - Session 2

11:10 Capture, Thermalization and Annihilation of Dark Matter in Neutron Stars

Neutron stars (NSs) are promising cosmic laboratories to test the nature of dark matter (DM). DM captured by the strong gravitational field of these stellar remnants transfers its kinetic energy to the star through subsequent collisions with the star constituents. Further DM annihilation can add extra heating. This can produce anomalous heating of old neutron stars. While DM deposits its kinetic energy quite quickly, in order for appreciable annihilation heating to be achieved, capture and annihilation processes should reach a state of equilibrium. In light of this, we revisit the calculation of the DM capture rate, thermalization, and capture-annihilation equilibrium timescales in NSs, making little approximations about the physics of neutron stars. We show that capture-annihilation equilibrium, and hence maximal annihilation heating, can be achieved without complete thermalization of the captured dark matter for all types of dark matter - baryon interactions. This includes cases where the scattering or annihilation cross sections are momentum or velocity suppressed in the non-relativistic limit. For scattering cross sections that saturate the capture rate, we find that capture-annihilation equilibrium is typically reached on a timescale of less than $1$ year for vector interactions and $10^4$ years for scalar interactions.

Speaker: Sandra Robles (Fermilab)

DM_capture_NSs_QMDM.pdf

11:45 Dark matter heating vs. vortex creep heating in old neutron stars

Dark matter can be captured in a neutron star and deposits its energy into a star. This dark matter heating effect, however, can be observed only if it dominates over other internal heating effects in neutron stars. In this work, as such an internal heating effect, we examine the frictional heating caused by the creep motion of neutron superfluid vortex lines in the neutron star crust. The luminosity of this heating effect is controlled by the strength of the interaction between the vortex lines and nuclei in the crust. We estimated this luminosity in two approaches; (1) the estimation through the temperature observation of old neutron stars and (2) the estimation from the many-body calculation of a high-density nuclear system. We find that both approaches suggest that the vortex creep heating dominates over the DM heating. The vortex-nuclei interaction must be smaller than the estimated values by several orders of magnitude to overturn this domination.

Speaker: Motoko Fujiwara (Technical University of Munich)

Motoko_Fujiwara-QMDM.pdf

12:10 Probing Dark Matter Interactions through White Dwarf Observations

The scattering of dark matter from stellar constituents leads to gravitational capture, with important observational consequences. In particular, white dwarf heating occurs due to the energy transfer in the dark matter capture and thermalisation processes, and the subsequent annihilation of captured dark matter. Here I will discuss the capture of dark matter, our study investigates a model where dark matter interacts with white dwarf ion components via a light scalar mediator. We apply this technique to observations of old white dwarfs in the globular cluster Messier 4, which we assume to be located in a DM subhalo.

Speaker: Maura E. Ramirez-Quezada (Johannes-Gutenberg Universität Mainz)

QMDM2024_03.pdf

12:35 The impact of dark matter on neutron stars and gravitational wave signals from their mergers

Compact stars due to their enormous gravitational field can accumulate a sizable amount of dark matter in their interior. Depending on its nature, accumulated dark matter may affect the properties of neutron stars in quite different ways. I will give an overview of the impact of dark matter on various observable properties of neutron stars, i.e. the mass-radius relation, tidal deformability, merger dynamics, gravitational waveform, thermal evolution, etc. For two scenarios, asymmetric fermionic and bosonic dark matter, the conditions at which dark matter particles tend to condense in the core of the star or create an extended halo will be presented. I will show how dark matter condensed in a core tends to decrease the total gravitational mass and tidal deformability compared to a pure baryonic star, which appears as an effective softening of the equation of state. On the other hand, the presence of a dark matter halo has the opposite effect, causing an increase in those observable quantities. Thus, observational data on compact stars could be affected by accumulated dark matter and, consequently, constraints we put on the strongly interacting matter at high densities.

In addition, I will review the effect of DM on binary neutron star mergers and emitted gravitational wave signals. I will present the numerical-relativity simulations of compact stars admixed with the dark matter component and discuss how the ongoing and future X-ray, radio, and gravitational wave observations could shed light on dark matter admixed compact stars and put multi-messenger constraints on the corresponding effect.

Speaker: Violetta Sagun (University of Coimbra)

dmcore_4k.mp4

dm_halo_4k.mp4

QMDM_Sagun.pdf

13:00 How Axions change the Stellar Landscape

Speaker: Konstantin Springmann (Technische Universität München)

9_KS_Quarkonia.pdf

13:30 → 13:40 Conclusion & Goodbye

Speaker: Nora Brambilla (Physik Department, TU Munich)

close.pdf