Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session KC: Mini-Symposium on Baryons with Spatial and Flavor Excitations I |
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Chair: Tetsuo Hyodo, Yukawa Institute of Theoretical Physics Room: Kohala 3 |
Saturday, October 11, 2014 9:00AM - 9:30AM |
KC.00001: Dynamics of Heavy Quarks in the Heavy Baryon Spectrum Invited Speaker: Makoto Oka Recent developments in hadron spectroscopy bring novel ideas and pictures to structures and dynamics of quarks in hadrons. I overview recent achievements in the baryon spectroscopy, and further focus the discussion on heavy quark baryons and their excited states. \\ The heavy quarks have masses much higher than the QCD energy scale, $\Lambda_{\rm QCD}$. This hierarchy brings new features and symmetry of heavy hadrons, containing one or more heavy quarks. We study manifestations of heavy quark dynamics and symmetry in the spectrum of the heavy baryons, in particular the charmed baryons. It is found that the characteristic excitation patterns are observed and the spectra and decays of the excited states will give us much information on the dynamics of both the heavy and light quarks. Relation to the strange baryon spectrum is also discussed. [Preview Abstract] |
Saturday, October 11, 2014 9:30AM - 9:45AM |
KC.00002: Pion induced Reactions for Charmed Baryons Atsushi Hosaka, Sang-Ho Kim, Hyun-Chul Kim, Hiroyuki Noumi, Kotaro Shirotori We study pion induced reactions for charmed baryons $B$, $\pi + N \to D^* + B$. First we estimate charm production rates in comparison with strangeness production using a Regge model which is dominated by vector ($D^*$ or $K^*$) Reggeon exchange. Then we examine the production rates of various charmed baryons $B$ in a quark-diquark model. We find that the production of excited states are not necessarily suppressed, a sharp contrast to strangeness production, which is a unique feature of the charm production with a large momentum transfer. [Preview Abstract] |
Saturday, October 11, 2014 9:45AM - 10:00AM |
KC.00003: Baryon spectroscopy with heavy flavors at J-PARC Hiroyuki Noumi How are hadrons formed? This is a fundamental question in hadron physics. The constituent quark model describes the properties of hadrons in the ground state rather successfully. However, it fails in some excited states, where another effective degrees of freedom, such as diquarks, hadrons, and/or other quark/gluon clusters, may play important roles in hadrons. To answer the above-mentioned question, we need to understand the dynamics of ingredients of hadrons further. Baryons with heavy flavors (heavy baryons) provide unique opportunities to investigate quark dynamics in baryons. Owing to the so-called heavy quark symmetry in QCD, heavy baryons are characterized by the motions of the heavy quark(s) and the others. For example, we expect that the nature of light-$qq$ diquark motions in charmed baryons appears in the level structure, production rates, and decay branching ratios. Therefore, we proposed a spectroscopic study of charmed baryons via the $p(\pi^-,D^{*-})$ reaction at the J-PARC high-momentum beam line (P50). Systematic measurements of the excitation energy spectrum and decays of charmed baryons can be carried out by means of the missing mass technique with a large acceptance spectrometer. I will introduce the proposed experiment and discuss possible studies. [Preview Abstract] |
Saturday, October 11, 2014 10:00AM - 10:15AM |
KC.00004: Study for the elementarity of composite systems Hideko Nagahiro, Atsushi Hosaka Recently, the hadronic composite states have been studied extensively in the context of the dynamically generated states. The question of ``elementarity'' has been studied by using the wave function renormalization constant $Z$ [1, 2]. The attempts have been made not only for bound states but also for resonant states [3--5]. In this talk, we show that the renormalization constant $Z$ can be zero for any composite state dynamically generated by a Weinberg-Tomozawa type interaction. We discuss the underlying mechanism of $Z=0$ for composite systems and how we should employ the renormalization constant $Z$ to understand the nature of hadrons [6]. We also discuss a special case of the zero-energy bound state. We show that the meaning of the condition $Z=0$ for a barely bound system can be different from that of finite binding energy or resonant case. \\[4pt] [1] S. Weinberg, PR130(63)776; PR137(65)B672.\\[0pt] [2] D. Lurie and A. J. Macfarlane, PR136(64)B816.\\[0pt] [3] T. Hyodo, D. Jido, and A. Hosaka, PRC85(12)015201.\\[0pt] [4] H. Nagahiro et al., PRD83(11)111504.\\[0pt] [5] H. Nagahiro and A. Hosaka, PRC88(13)055203.\\[0pt] [6] H. Nagahiro and A. Hosaka, e-print arXiv:1406.3684 [hep-ph]. [Preview Abstract] |
Saturday, October 11, 2014 10:15AM - 10:30AM |
KC.00005: P-wave heavy baryons with the constituent quark model Tetsuya Yoshida, Makoto Oka, Atsushi Hosaka, Emiko Hiyama, Katsunori Sadato Spectroscopy of excited baryons with heavy quark is one of the major subject in the hadron experimental facilities, such as J-PARC and GSI. It is very important to give predictions and physics guidelines in advance from theory. Lattice QCD is very successful for the ground states, but it has some difficulty in predicting excited states. Therefore it is necessary to construct a reliable model for the spectroscopy for the heavy baryons. We construct a constituent quark model which is well tuned in the strangeness sector and analyze the excited states of charmed and bottomed baryons. We focus our study to the P-wave excited states and perform a precise calculation. We analyze two characteristic excitation modes, the $\lambda$-mode and the $\rho$-mode. From the analysis, we get information on the structure of heavy baryons, which characterizes the production and decay mechanisms and patterns. Such information should be very useful for experimental identification of these excited states. [Preview Abstract] |
Saturday, October 11, 2014 10:30AM - 10:45AM |
KC.00006: Excited Baryon Structure Using KY Exclusive Reactions With CLAS12 Daniel Carman Studying excited nucleon structure via exclusive $KY$ electroproduction will be an important tool for exploring the non-perturbative strong interaction. Electrocouplings for low-lying $N^*$ states ($<$1.7 GeV) have been determined from analyses of CLAS $\pi N$ and $\pi \pi N$ data. This work made clear that consistency of independent analyses of exclusive channels with different couplings and non-resonant contributions is essential to have confidence in the extracted results. In terms of hadronic coupling, most high-lying $N^*$ states preferentially decay through the $\pi\pi N$ channel instead of $\pi N$. Data from the $KY$ channels will therefore be critical to provide an independent analysis to compare the extracted electrocouplings for the high-lying $N^*$ states against those determined from the $\pi\pi N$ channel from an already approved CLAS12 12-GeV experiment. A new experiment that will focus on $N^* \to KY$ decays using CLAS12 at JLab will be discussed that will measure differential cross sections to be used as input to extract the $\gamma_vNN^*$ transition form factors for the most prominent $N^*$ states in the range of invariant energy $W$ from 1.6 to 3~GeV in the virtually unexplored domain of momentum transfers $Q^2$ up to 12~GeV$^2$. [Preview Abstract] |
Saturday, October 11, 2014 10:45AM - 11:00AM |
KC.00007: Dynamical coupled-channels study of hyperon resonances via anti-kaon-nucleon reactions Hiroyuki Kamano, Satoshi Nakamura, T.-S. Harry Lee, Toru Sato We develop a dynamical coupled-channels model of $K^- p$ reactions for the purpose of establishing mass spectrum of hyperon resonances and determining the partial wave amplitudes of the elementary anti-kaon-nucleon reactions. The channel space of the model is spanned by the two-body $\bar K N$, $\pi \Sigma$, $\pi \Lambda$, and $K\Xi$ channels as well as the three-body $\pi \pi \Lambda$ and $\pi \bar K N$ channels that have the quasi-two-body $\pi\Sigma^*$ and $\bar K^* N$ components. The model parameters are fixed by a comprehensive analysis of the available unpolarized and polarized observables of $K^- p \to \bar K N, \pi \Sigma, \pi \Lambda, K\Xi$ reactions from the threshold up to $\sqrt{s} = 2.1$ GeV. In this talk, we report the current status of the comprehensive multichannel analysis of $K^-p$ reactions and the extracted parameters (pole masses and coupling strengths defined by the residues of the scattering amplitudes at the pole) of hyperon resonances. We also discuss about the role of the reaction dynamics for understanding various properties of hyperon resonances. [Preview Abstract] |
Saturday, October 11, 2014 11:00AM - 11:15AM |
KC.00008: Symmetric and anti-symmetric LS hyperon potentials from lattice QCD Noriyoshi Ishii, Keiko Murano, Hidekatsu Nemura, Kenji Sasaki, Takashi Inoue We present recent results of odd-parity hyperon-hyperon potentials from lattice QCD. By using HAL QCD method, we generate hyperon-hyperon potentials from Nambu-Bethe-Salpeter (NBS) wave functions generated by lattice QCD simulation in the flavor SU(3) limit. Potentials in the irreducible flavor SU(3) representations are combined to make a Lambda-N potential which has a strong symmetric LS potential and a weak anti-symmetric LS potential. We discuss a possible cancellation between symmetric and anti-symmetric LS (Lambda-N) potentials after the coupled Sigma-N sector is integrated out. [Preview Abstract] |
Saturday, October 11, 2014 11:15AM - 11:30AM |
KC.00009: Exclusive single pion electroproduction off the proton in the invariant mass range up to 2 GeV and at Q2$<$5GeV2 with CLAS. Kijun Park, Volker Burkert Exclusive meson electroproduction off protons is a powerful tool to probe the effective degrees of freedom in excited nucleon states at the varying distance scale where the transition from the contributions of both quark core and meson-baryon cloud to the quark core dominance. During the past decade, the CLAS collaboration has executed a broad experimental program to study the excited states of the proton using polarized electron beam and (un)polarized proton targets. The measurements covered a broad kinematic range in the invariant mass W and photon virtuality Q2 with nearly full coverage in solid angles in the hadronic CMSystem. As results, several low-lying nucleon resonance states have been explored, such as $\Delta$(1230)3/2+, N(1440)1/2+, N(1520)3/2-, and N(1535)1/2- in particular for W$<$1.6 GeV. In this talk, we present preliminary cross-sections and helicity amplitudes of the reaction g*p$\to$npi+ at higher W (1.6 to 2.0 GeV). Some of the excited states with isospin 1/2 and with masses near 1.7 GeV can be accessed in single npi+ production as there are no isospin 3/2 states present in this mass range with the same spin-parity assignments. These are the N(1675)5/2-, N(1680)5/2+, and N(1710)1/2+ states. We will briefly discuss preliminary results for these states. [Preview Abstract] |
(Author Not Attending)
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KC.00010: Polarization observables for double charged pion photo-production with polarized HD target Peng Peng A complete characterization of the spectrum of N* and Delta resonances for nucleon is essential to understand the internal structure of the nucleon. However, both the recent Lattice QCD calculation and the conventional Constitute Quark Model have predicted more resonances than experimentally observed. In order to identify the missing resonances using partial wave analysis, polarization observables are needed to be measured in experiment. The work presented in this talk is to analyze the polarization observables for double charged pion photo-production with polarized HD target (G14 experiment in Jlab). With circularly polarized beam, and longitudinal polarized target, both proton and neutron, three polarization observables in the double pion photo-production are measured. The proton data will be compared with an earlier Jlab experiment G9, and the new neutron data will also be presented. [Preview Abstract] |
Saturday, October 11, 2014 11:45AM - 12:00PM |
KC.00011: Spin observable measurements in pseudo scalar-meson polarized photo-production using polarized deutrons in solid HD Tsuneo Kageya Recent Lattice QCD calculations have supported the long standing quark model expectation of many more excited states of the nucleon than have been experimentally observed. These missing states are expected to be broad and overlapping and require detailed partial wave analyses (PWA) to disentangle. Measurements of many polarization observables are required to constrain PWA. Furthermore, for evaluation of isoscalar and isovector contributions to photocouplings of 1/2-isospin resonances, photocouplings both off protons and neutrons are needed. To address the latter, the g14/E06-101 experiment at Jlab completed data taking in 2012 using the CLAS with circularly and linearly polarized photons incident on longitudinally polarized neutrons in solid deuterium-hydride (HD) frozen-spin targets. Analysis has been on-going for the data with linearly as well as circularly polarized photon beams. Corrections have been performed for energy loss of charged particles passing through materials on the cryogenic target. Preliminary analyses for double-spin asymmetries on deutron, such as a reaction $\gamma$ + d $\rightarrow$ $\pi^-$ + p + X aiming to the one on neutron; $\gamma$ + n(p) $\rightarrow$ $\pi^-$ + p (p) will be discussed. [Preview Abstract] |
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