Conveners
Light Mesons: 1
- Wolfgang Ochs (research scientist)
Light Mesons: 2
- Wolfgang Dรผnnweber (Univ. Mรผnchen)
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
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Dr Jose R. Pelaez (Universidad Complutense)13/06/2011, 14:30Light MesonstalkThe 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...Go to contribution page
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Prof. Nikolay Achasov (Sobolev Institute for Mathematics)13/06/2011, 15:00Light MesonstalkThe 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...Go to contribution page
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Prof. Evgeny Solodov (Budker INP)13/06/2011, 15:20Light MesonstalkTwo-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...Go to contribution page
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Prof. Evgeny Solodov (Budker INP)13/06/2011, 15:40Light MesonstalkWe 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...Go to contribution page
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Dr Rainer Schicker (Phys. Inst.)13/06/2011, 16:30Light MesonstalkR. 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...Go to contribution page
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Dr Wolfgang Ochs (research scientist)13/06/2011, 17:00Light MesonstalkThe 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.Go to contribution page
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Prof. Martin Schumacher (Zweites Physikalisches Institut der Universitรคt Gรถttingen)13/06/2011, 17:20Light MesonstalkThe 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...Go to contribution page
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Eulogio Oset (IFIC , University of Valencia)13/06/2011, 17:40Light MesonstalkWe 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...Go to contribution page
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Prof. Dmitri Melikhov (HEPHY Vienna Austria & SINP Moscow Russia)14/06/2011, 16:30Light MesonstalkWe 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 Schrรถdinger equation and confronted with the result from the...Go to contribution page
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Mr Bastian Brandt (Institut fuer Kernphysik, Johannes Gutenberg-Universitaet, Mainz)14/06/2011, 16:50Light MesonstalkWe 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...Go to contribution page
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Prof. Volker Metag Metag (II. Physikalisches Institut)14/06/2011, 17:10Light MesonstalkVolker Metag University of Giessen, Germany for the A2 collaboration The Dalitz decay ฮท โ ฮณe+eโ 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...Go to contribution page
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Dr camilla di donato (INFN Sez. Napoli)14/06/2011, 17:30Light MesonstalkThe 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...Go to contribution page
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Mr Prometeusz Jasinski (INP Mainz)14/06/2011, 17:50Light MesonstalkIn 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...Go to contribution page
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Dr Dennis Weygand (Jefferson Laboratory)16/06/2011, 14:30Light MesonstalkThe 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...Go to contribution page
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Prof. Chaden Djalali (University of South Carolina)16/06/2011, 15:00Light MesonstalkRecent studies of light vector meson production in heavy nuclear targets has generated interest in ฯ-ฯ 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 Labโs CLAS detector with tagged photon...Go to contribution page
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Dr Zhi-Hui Guo (Universidad de Murcia)16/06/2011, 15:20Light MesonstalkWe 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...Go to contribution page
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Jenifer Nebreda (Universidad Complutense de Madrid)16/06/2011, 15:40Light MesonstalkWe 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...Go to contribution page
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Craig Bookwalter (Florida State University)16/06/2011, 16:30Light Mesonstalk\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,...Go to contribution page
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Dr Dmitry Ryabchikov (Institute for High Energy Physics)16/06/2011, 16:50Light MesonstalkThe 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...Go to contribution page
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Mr Tobias Schlรผter (LMU Munich)16/06/2011, 17:10Light MesonstalkFrom 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...Go to contribution page
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Dr Bachir Moussallam (IPN Orsay)16/06/2011, 17:30Light MesonstalkSome 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...Go to contribution page
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Dr Gurjav Ganbold (Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Russia)16/06/2011, 17:50Light MesonstalkThe 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...Go to contribution page
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Prof. Evgeny Solodov (Budker INP)17/06/2011, 09:00Light MesonstalkRegular 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.Go to contribution page
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Mr Florian Haas (Physik-Department E18 Technische Universitรคt Mรผnchen)17/06/2011, 09:20Light MesonstalkDiffractive 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...Go to contribution page
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Dr Frank Nerling (University of Freiburg)17/06/2011, 09:40Light MesonstalkThe 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...Go to contribution page
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Dr Luis Roca (University of Murcia)17/06/2011, 10:00Light MesonstalkIn 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...Go to contribution page
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Prof. Hideko Nagahiro (Nara Women's University)17/06/2011, 10:20Light MesonstalkWe 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...Go to contribution page
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Ms Hongwei LIU (Institute of High Energy Physics)17/06/2011, 10:40Light MesonstalkWith 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 $J/\psi\rightarrow\gamma\pi^+\pi^-\eta^\prime$...Go to contribution page