Conveners
Light Mesons: 1
- Wolfgang Ochs (research scientist)
Light Mesons: 2
- Wolfgang Dünnweber (Univ. München)
Light Mesons: 3
- Dennis Weygand (Jefferson Laboratory)
Light Mesons: 4
- Volker Crede (Florida State University)
Light Mesons: 5
- Paul Eugenio (Florida State University)
Light Mesons: 6
- Claude Marchand (CEA IRFU/SPhN Saclay)
Description
Spectroscopy and decay of light mesons
Dr
Jose R. Pelaez
(Universidad Complutense)
6/13/11, 2:30 PM
Light Mesons
talk
The leading $1/N_c$ behaviour of Unitarised Chiral Perturbation Theory distinguishes the nature of the $\rho$ and the $\sigma$. At one loop order the $\rho$ is a ${\bar q}q$ meson, while the $\sigma$ is not. However, semi-local duality between resonances and Regge behaviour cannot be satisfied for larger $N_c$, if such a distinction holds. While the $\sigma$ at $N_c=3$ is inevitably dominated...
Prof.
Nikolay Achasov
(Sobolev Institute for Mathematics)
6/13/11, 3:00 PM
Light Mesons
talk
The light scalar meson problem which has arisen 50 years ago from the linear sigma model ( LSM), became central in the nonperturbative QCD since LSM could be its low energy realization. The scalar channels in the region up to 1 GeV is a stumbling block of QCD. The point is that not only perturbation theory fails here, but sum rules as well in view of the fact that isolated resonances are...
Prof.
Evgeny Solodov
(Budker INP)
6/13/11, 3:20 PM
Light Mesons
talk
Two-photon processes can be studied at e+e- colliders via the reaction e+ e- -> e+ e- gamma gamma(*) -> e+ e- X, providing a suitable environment for hadron spectroscopy and tests of QCD predictions.
We report recent measurements of the gamma gamma* -> P transition form factors at large values of momentum transfer -- where P is a pseudoscalar meson: pi0, eta, eta', and eta_c -- performed in...
Prof.
Evgeny Solodov
(Budker INP)
6/13/11, 3:40 PM
Light Mesons
talk
We report on latest results obtained at BABAR studying low energy e+e- annihilations, produced via initial state radiation. Hadronic cross sections are the experimental input for calculation of the muon anomalous magnetic moment, while the study of the final states and intermediate structures with unprecedented accuracy can reveal new states and their properties. In particular, an updated...
Dr
Rainer Schicker
(Phys. Inst.)
6/13/11, 4:30 PM
Light Mesons
talk
R. Schicker for the ALICE Collaboration
The ALICE experiment at the Large Hadron Collider (LHC) at CERN consists of a central barrel covering the pseudorapidity range -0.9 < eta < 0.9 and of additional detectors which can be used to define pseudorapidity gaps -3.7 < eta < -0.9 and 0.9 < eta < 5.1. The low pT threshold of the central barrel gives ALICE a unique opportunity to study the low...
Dr
Wolfgang Ochs
(research scientist)
6/13/11, 5:00 PM
Light Mesons
talk
The existence of glueballs within QCD is uncontroversial but their experimental verification is still in doubt. We discuss the new possibilities for a search of glueballs as the leading object in gluon jets at the LHC and also recall previous results from LEP.
Prof.
Martin Schumacher
(Zweites Physikalisches Institut der Universität Göttingen)
6/13/11, 5:20 PM
Light Mesons
talk
The scalar mesons sigma(600), kappa(800), f0(980) and a0(980) together with the pseudo Goldstone bosons pi, K and eta may be considered as the Higgs sector of strong interaction. After a long time of uncertainty about the internal structure of the scalar mesons there now seems to be consistency which is in line with the major parts of experimental observations. Great progress has been made by...
Eulogio Oset
(IFIC , University of Valencia)
6/13/11, 5:40 PM
Light Mesons
talk
We develop a scheme on how to obtain the lightest scalar mesons from hypothetical QCD lattice results.
The latter are simulated by using the two channel chiral unitary approach for and K Kbar scattering that
generates the f0(600) and f0(980) resonances. We re-derive Luescher formula for one channel in a very
simple way suited to practitioners of the chiral unitary approach, and then from...
Prof.
Dmitri Melikhov
(HEPHY Vienna Austria & SINP Moscow Russia)
6/14/11, 4:30 PM
Light Mesons
talk
We calculate the pion form factor making use of a local-duality (LD) version of QCD sum rules. To probe the accuracy of the obtained predictions we consider in parallel to QCD a potential model with an interaction consisting of Coulomb and confining parts. In this case, the exact form factor may be obtained from the solution of the Schrödinger equation and confronted with the result from the...
Mr
Bastian Brandt
(Institut fuer Kernphysik, Johannes Gutenberg-Universitaet, Mainz)
6/14/11, 4:50 PM
Light Mesons
talk
We present a lattice calculation of the vector form factor of the pion for two flavours of non-perturbatively O(a) improved Wilson fermions. For the measurements we utilise the CLS ensembles which include various lattice spacings and pion masses down to roughly 250 MeV. To obtain a fine momentum resolution near zero momentum transfer (q^2) twisted boundary conditions are employed using several...
Prof.
Volker Metag Metag
(II. Physikalisches Institut)
6/14/11, 5:10 PM
Light Mesons
talk
Volker Metag
University of Giessen, Germany
for the A2 collaboration
The Dalitz decay η → γe+e− has been investigated in photo-nuclear reactions with the Crystal Ball/TAPS detector system at the electron accelerator MAMI-C. The Dalitz decay events were identified in an exclusive analysis exploiting the full kinematic information. Statistics improved by an order of magnitude compared to...
Dr
camilla di donato
(INFN Sez. Napoli)
6/14/11, 5:30 PM
Light Mesons
talk
The KLOE experiment has collected 2.5 fb-1 at the peak of the phi resonance at the e+e- collider DAPHNE in Frascati. The whole data set includes 100 million eta's produced through the radiative decay phi --> eta gamma and tagged by means of the monochromatic recoil photon. Measurements of eta decay channels, such as pi+ pi- gamma, are in progress. We have also measured the branching ratio of...
Mr
Prometeusz Jasinski
(INP Mainz)
6/14/11, 5:50 PM
Light Mesons
talk
In order to study the light mesons spectrum the COMPASS experiment at CERN took data with a 190 GeV/c hadron beam hitting a liquid hydrogen target in the years 2008 and 2009.
The negative hadron beam contains mainly pions and a small fraction of about 2.5\% of kaons.
Kaons are identified using CEDAR PID detectors in the beamline.
One of the channels of interest are diffractively produced...
Dr
Dennis Weygand
(Jefferson Laboratory)
6/16/11, 2:30 PM
Light Mesons
talk
The g12 experimental period (April - June 2008) at the CEBAF Large Angle Spectrometer (CLAS) at Jefferson Laboratory was a high-luminosity photon run at the highest CEBAF
energies. A tagged bremsstrahlung beam was available between 1.2 and 5.7 GeV with a raw integrated luminosity of 68 pb$^{-1}$, 27 pb$^{-1}$ in the high energy range greater than 4.4 GeV. The principal aim of the experiment...
Prof.
Chaden Djalali
(University of South Carolina)
6/16/11, 3:00 PM
Light Mesons
talk
Recent studies of light vector meson production in heavy nuclear targets
has generated interest in ρ-ω interference in the leptonic decay channel. An
experimental study of the elementary process provides valuable input for
theoretical models and calculations. In experiment E04-005, high statistics
photoproduction data has been taken in Jefferson Lab’s CLAS detector with
tagged photon...
Dr
Zhi-Hui Guo
(Universidad de Murcia)
6/16/11, 3:20 PM
Light Mesons
talk
We first present the full one-loop calculation of meson-meson scattering in the framework of U(3) chiral perturbation theory with explicit resonance states in the Lagrangian. After the partial wave projection and resummation of the unitarity loops, we fit our theoretical formulas to the data to fix the free parameters and then calculate the resonance pole positions and residues, such as...
Jenifer Nebreda
(Universidad Complutense de Madrid)
6/16/11, 3:40 PM
Light Mesons
talk
We report on our recent results [1] in the study of the chiral extrapolation of the phase-shifts in elastic pion-pion scattering, using both standard and unitarized ChPT to one and two loops. In the standard ChPT approach, limited to low momenta, we study the S, P and D waves. For the vector phase shift we find a behavior that would seemingly contradict the results of lattice and other...
Craig Bookwalter
(Florida State University)
6/16/11, 4:30 PM
Light Mesons
talk
\par In addition to ordinary $q\bar{q}$ pairs, quantum chromodynamics (QCD) permits many other possibilities in meson spectra, such as gluonic hybrids, glueballs, and tetraquarks.
Experimental discovery and study of these exotic states provides insight on the nonperturbative regime of QCD.
Over the past twenty years, some searches for exotic mesons have met with controversial results,...
Dr
Dmitry Ryabchikov
(Institute for High Energy Physics)
6/16/11, 4:50 PM
Light Mesons
talk
The Partial-Wave analysis of the reaction:
pi- Be -> pi-pi-pi+eta Be with E_beam = 28 GeV is performed
in full 4-body mesonic final state phase-space.
In the wide range of momentum transfer t' = 0.-1. GeV/c^2 the
dominance of diffractive-like (natural-parity exchange) mechanism is demonstrated.
The individual partial waves in f1(1285) pi-, eta'pi- and a2(1320) eta systems are...
Mr
Tobias Schlüter
(LMU Munich)
6/16/11, 5:10 PM
Light Mesons
talk
From COMPASS 2008 data a sample of 40,000 events of the type $\pi^-p\to\eta'(\to\eta(\gamma\gamma)\pi^+\pi^-)\pi^-p_{\textrm{slow}}$ with $-t>0.1\,\textrm{GeV}^2/c^2$ was selected for a partial-wave analysis. Monte Carlo simulations display a smooth dependence of the acceptance on kinematic variables. Study of the alternative final state with $\eta\to\pi^+\pi^-\pi0(\gamma\gamma)$ provides a...
Dr
Bachir Moussallam
(IPN Orsay)
6/16/11, 5:30 PM
Light Mesons
talk
Some properties of the scalar mesons sigma(600) and f0(980) are
discussed using the Roy integral equations to control continuations in the complex energy plane.
On the real axis, firstly, high precision numerical solutions of the equations are constructed for energies up to the K-Kbar threshold.
Fits to the data by such solutions are performed and constrained by the recent measurements of...
Dr
Gurjav Ganbold
(Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Russia)
6/16/11, 5:50 PM
Light Mesons
talk
The spectroscopy of light- and heavy-quark mesons as well as the lowest-state glueball state are investigated within a relativistic quantum-field model based on analytical confinement. Ladder Bethe-Salpeter-type equations are derived to define the spectra of quark-antiquark and two-gluon bound states. We provide a new analytic estimate of the lowest-state glueball mass and calculate spectra...
Prof.
Evgeny Solodov
(Budker INP)
6/17/11, 9:00 AM
Light Mesons
talk
Regular data taking is going on in Novosibirsk at VEPP2000 e+e- collider. Two new (or significantly modified) detectors a in operation at two available interaction region. Luminosity up to 10**31 has been reached so far, limited by positron source.
First 1-2 GeV c.m. energy scan has been performed and first preliminary results on e+e- -> hadrons, barions
are demonstrated by two detector teams.
Mr
Florian Haas
(Physik-Department E18 Technische Universität München)
6/17/11, 9:20 AM
Light Mesons
talk
Diffractive dissociation reactions studied at the COMPASS experiment, CERN, provide access to the light meson spectrum. During a pilot run in 2004, using a pion beam and a lead target, 500k events of pi- pi- pi+ final state events with masses below 2.5 GeV/c^2 were recorded, yielding a significant signal for the p1(1600) spin-exotic resonance. After a significant upgrade of the spectrometer in...
Dr
Frank Nerling
(University of Freiburg)
6/17/11, 9:40 AM
Light Mesons
talk
The COMPASS experiment at CERN SPS features charged particle tracking as well as good coverage by electromagnetic calorimetry, and our data provide excellent opportunity for simultaneous observation of new states in different decay modes in the same experiment. The existence of the spin-exotic $\pi_1(1600)$ resonance in the $\rho\pi$ decay channel is studied for the first time in COMPASS in...
Dr
Luis Roca
(University of Murcia)
6/17/11, 10:00 AM
Light Mesons
talk
In previous works regarding the interaction of two vector mesons using the techniques of the chiral unitary approach, it was shown that the vector-vector interaction in s-wave with spins aligned is very strong both for rho-rho and K*-rho to the point to get dynamically the f2(1270) and K*2(1430) resonances. In the work presented in this talk we use the rho-rho and rho-K* interaction in spin 2...
Prof.
Hideko Nagahiro
(Nara Women's University)
6/17/11, 10:20 AM
Light Mesons
talk
We propose a practical method to clarify the mixing nature of hadrons consisting of multiple components having different origins, by demonstrating an analysis of the a1(1260) meson [1].
One of recent interests in hadron structure is whether hadrons are made up of quarks as described in the conventional quark model, or develop subcomponents of quark-clusters inside. One good example is...
Ms
Hongwei LIU
(Institute of High Energy Physics)
6/17/11, 10:40 AM
Light Mesons
talk
With samples of 220 million $J/\psi$ events and 110 million $\psi^\prime$ events collected in the BESIII detector, $p\bar{p}$ mass threshold enhancement is studied. The enhancement is evident in $J/\psi$ radiative decay, which is consistent with BESII result. No significant narrow enhancement is observed in $\psi^\prime$ radiative decay. For $J/\psi\rightarrow\gamma\pi^+\pi^-\eta^\prime$...