Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session R10: Hadronic Physics III |
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Sponsoring Units: DNP Chair: Matthew Shepherd, Indiana University Room: Garden 1 |
Monday, May 2, 2011 1:30PM - 1:42PM |
R10.00001: Low-energy antikaon nucleon and nucleus interaction studies Johann Marton The antikaon (K-) interaction on nucleons and nuclei at low energy is neither simple nor well understood. Kaonic hydrogen is a very interesting case where the strong interaction of K- with the proton leads to an energy shift and a broadening of the 1s ground state. These two observables can be precisely studied with x-ray spectroscopy. The behavior at threshold is influenced strongly by the elusive Lambda(1405) resonance. In Europe the DAFNE electron-positron collider at Laboratori Nazionali di Frascati (LNF) provides an unique source of monoenergetic kaons emitted in the Phi meson decay. Recently the experiment SIDDHARTA on kaonic hydrogen and helium isotopes was successfully performed at LNF. A European network LEANNIS with an outreach to J-PARC in Japan was set up which is promoting the research on the antikaon interactions with nucleons and nuclei. This talk will give an overview of LEANNIS research tasks, the present status and an outlook to future perspectives. [Preview Abstract] |
Monday, May 2, 2011 1:42PM - 1:54PM |
R10.00002: GPD Evolution for a Scalar Particle Hikmat BC, Matthias Burkardt We study the Generalized Parton Distribution (GPD) parameterization which aims at investigating how accurately GPDs can be extracted from DVCS data taken over a wide range of Q$^{2}$. The results indicate that from mathematical point of view a unique GPD extraction is possible. We have investigated that how experimental uncertainties and the limited range over which DVCS data will impede the GPD extraction. [Preview Abstract] |
Monday, May 2, 2011 1:54PM - 2:06PM |
R10.00003: Asymptotical contributions to pion electromagnetic and transition form factor Peng Guo, Mikhail Gorchtein, Adam Szczepaniak We present a calculation of the pion electromagnetic and transition from factors in the framework of dispersion relations. At low energies (time-like virtual photon masses), the input in the dispersion relation is obtained by solving the coupled channel problem for the $\pi\pi$ and $K\bar K$ scattering in a fully unitarized K-matrix approach. At high energies, we propose a model that features novel colored Regge exchange contributions. The parameters of these Regge exchanges can be related to the high energy behavior of meson-meson scattering amplitudes. The recent data on the transition $\gamma^*\to\pi^0\gamma$ form factor by BaBar collaboration can be explained in our model with no further adjustments. [Preview Abstract] |
Monday, May 2, 2011 2:06PM - 2:18PM |
R10.00004: Hadronization dynamics of $\Lambda^{0}$ baryon Lamiaa El Fassi One of the most challenging studies in hadronic physics over the last few decades is to understand the interaction and formation of hadrons in terms of the quarks and gluons degrees of freedom. The nature of their confinement dynamics can be explored using measurements of hadron production on nuclear targets in semi-inclusive deep-inelastic scattering (SIDIS) of leptons. The reaction is a unique tool for understanding the hadronization process that leads from partons produced in the elementary interaction to hadrons observed experimentally. A new measurement, the JLab E02-104 experiment, was carried out in fall 2004 using a 4 $\pi$ spectrometer, CLAS, to measure several hadrons produced in SIDIS from different nuclei (deuterium, carbon, iron and lead) at moderate momentum transfer, $Q^2$, values. Preliminary results of two fundamental observables, the hadronic multiplicity ratio $R^h_M$ and the transverse momentum broadening $\Delta$p$_T^2$, of one of the hadron species, $\Lambda^{0}$, will be highlighted in this presentation. This is the first time these observables have been measured for the $\Lambda^{0}$, adding new information that will be relevant to the study of baryon hadronization. All the compiled results from these high precision data will improve our understanding of the space-time evolution from quark propagation to hadronization at intermediate energy. [Preview Abstract] |
Monday, May 2, 2011 2:18PM - 2:30PM |
R10.00005: Spin doublet $(1^-,2^-)$ of ${ }_\Lambda ^6 $He within three-body cluster model Vladimir Suslov, Igor Filikhin, Branislav Vlahovic The spin doublet $(1^-,2^-)$ of ${ }_\Lambda ^6 $He is interesting as a test for theoretical models of the hyperon-nucleon interaction. The experimental value for the binding energy of the $1^-$ state (singlet spin state) of ${ }_\Lambda ^6 $He is known (-0.17 MeV) [1]. There are no experimental data for the $2^-$ state (triplet spin state). Theoretical considerations for the $2^-$state of ${ }_\Lambda ^6 $He have been attempted by Motoba et al. in [2] and Hiyama et al. in [3]. Indirect prediction for the $2^-$ state has been done in [4]. The results obtained in these works are quite different. Our goal is to get a new prediction for the $_\Lambda ^6 $He hypernucleus, which is considered as a cluster system $\alpha n\Lambda $, by using new proposed potentials [5] for the$\alpha \Lambda $and $\alpha n$ interactions. Our cluster approach is based on the configuration-space Faddeev equations for a system of three non-identical particles. The energy of the ($1^-$,$2^-)$ spin doublet for different $n\Lambda $ potentials [6] is calculated. Our results are compared with those obtained in other calculations and experimental data. [1] L. Majling, Proc. Natl. Conf. on Physics of Few-Body and Quark-Hadronic System (Kharkov, Ukraine, 1992). [2] T. Motoba at al. Prog. Theor. Phys. 70 189 (1983). [3] E. Hiyama at al. Phys. Rev. C 59 2351 (1999). [4] I. Filikhin at al. J. Phys. G: 31, 389 (2005). [5] I. Filikhin at al. EPJ Web of Conferences 3, 07004 (2010). [6] I. Filikhin, A. Gal, Phys. Rev. C 65 041001R (2002). [Preview Abstract] |
Monday, May 2, 2011 2:30PM - 2:42PM |
R10.00006: Gluon propagator in Color Glass Condensate and its Phenomenological Implications on Hadronic Cross Sections Man-Fung Cheung The interaction between a color condensate and strongly interacting particles has recently received a large amount of attention when one considers high energy hadronic collisions. In this work we consider the interaction between the quantum gluon and the classical background color field in the Color Glass Condensate (CGC) formalism. We present a gauge invariant formulation of the gluon-background field interaction where the background field carries a space-time dependence. Within this formalism, to leading order in the coupling constant and the strength of the background field, we show that the Slavnov-Taylor identities are satisfied. Based on this background modified gluon propagator the gluon-gluon elastic cross-section at high energy is calculated where the saturation parameter of the CGC medium is at $Q_s$. This cross section is found to be suppressed as $Q_s$ increases. The phenomenological implications of the modified propagator on the hadron-hadron and hadron-nucleus collision are presented. [Preview Abstract] |
Monday, May 2, 2011 2:42PM - 2:54PM |
R10.00007: Evidence for a Bound H-dibaryon from Lattice QCD Martin Savage The NPLQCD lattice collaboration finds evidence for the existence of a bound H-dibaryon at a pion mass of $m_\pi\sim 389~{\rm MeV}$. Using the results of Lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of $L\sim 2.0$, $2.5$, $3.0$ and $3.9~{\rm fm}$ at a spatial lattice spacing of $b_s\sim 0.123~{\rm fm}$, an H-dibaryon bound by $B = 16.6 \pm 2.1 \pm 4.6~{\rm MeV}$ at a pion mass of $m_\pi\sim 389$ MeV is found. I will discuss this calculation and its results. [Preview Abstract] |
Monday, May 2, 2011 2:54PM - 3:06PM |
R10.00008: Global Analyis of Exclusive Pion and Kaon Electroproduction Tanja Horn Exclusive pion and kaon electroproduction are important tools in the study of hadron structure, and in particular for our understanding of the dominant reaction mechanism in exclusive reactions. The dependence of the cross section on the Mandelstam variable $-t$ provides important information about the role of the $t$-channel meson exchange, which is also needed for the extraction of meson form factors. Increasing the photon virtuality, $Q^2$, in electron scattering experiments makes one more sensitive to the partonic picture, where soft non-perturbative and hard physics have been shown to factorize. In that regime, Generalized Parton Distributions (GPDs) provide the most complete description of the non-perturbative physics. Meson electroproduction at intermediate energies provides a good way to study the transition from the non-perturbative to the perturbative physics. In this talk I will review the world's data on exclusive p($e,e^\prime \pi^+$)n and the p($e,e^\prime K^+$)$\Lambda$ reactions, and show opportunities for further studies at future facilities. [Preview Abstract] |
Monday, May 2, 2011 3:06PM - 3:18PM |
R10.00009: Pseudoscalar Mass Spectrum in a Soft-Wall Model of AdS/QCD Sean Bartz, Thomas Kelley, Joseph Kapusta The Anti-de Sitter Space/Conformal Field Theory (AdS/CFT) correspondence may offer new and useful insights into the non-perturbative regime of strongly coupled gauge theories such as Quantum Chromodynamics (QCD). Recently a soft-wall AdS/QCD model exhibiting linear confinement was modified to incorporate independent sources for explicit and spontaneous chiral symmetry breaking. This model contains a modified dilaton and higher-order interaction terms in the Lagrangian. Within this model we explore the pseudoscalar sector using two common representations of the pion field, which are shown to be equivalent. We find the pseudoscalar mass eigenvalues in good agreement with the experimental pion masses. The Gell-Mann--Oakes--Renner relation is also naturally obtained. [Preview Abstract] |
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