Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session R13: Meson/Baryon Spectroscopy 
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Sponsoring Units: DNP GHP Room: Plaza Court 2 
Monday, April 15, 2013 1:30PM  1:42PM 
R13.00001: Spin observables used in determination of spinparity of cascade baryon resonances Benjamin Jackson, Kanzo Nakayama In preparation for the forthcoming experiments on multistrangeness baryon production at JLab and JPARC, we analyze the general features of cascade production in both the antikaon and photoninduced reactions. Particular attention is paid to the spin structure of the reaction amplitude for producing cascade resonances with the emphasis on identifying the spin observables required to determine the production amplitude as well as the spinparity of the resonance. For the production of cascade resonances with spin higher than 1/2, the spindensitymatrix formalism is proven to be particularly useful. The $\gamma N \to K K \Xi$ and $\bar{K}N \to K \Xi$ reactions are investigated within a simple model. [Preview Abstract] 
Monday, April 15, 2013 1:42PM  1:54PM 
R13.00002: $\pi^{+}\pi^{} p$ Electroproduction Cross Sections off Protons in the Second Resonance Region Gleb Fedotov, Ralf Gothe, Victor Mokeev In this talk we present preliminary $\pi^{+} \pi^{} p$ electroproduction cross sections off protons in the kinematical area of $W$ from 1.4 to 1.8~GeV and $Q^{2}$ from 0.4 to 1.1~GeV$^{2}$. Our kinematical coverage in part overlap with previous CLAS measurements, but offers more than a factor six finer binning in $Q^{2}$. The physics analysis of these data within the framework of the JM model will allow us to determine the electrocouplings and the partial $\pi \Delta$, $\rho p$ decay widths of several high lying nucleon resonances S$_{31}$(1620), S$_{11}$(1650), F$_{15}$(1685), D$_{33}$(1700), P$_{13}$(1720) and to further explore the evidence for the 3/2$^{+}$(1720) candidatestate. Analysis of the single pion electroproduction data measured with CLAS in the aforementioned kinematic region is in progress. Single and charged double pion exclusive channels are major contributors to the meson electroproduction in the N* excitation region with different nonresonant mechanisms. A successful description of all observables in these exclusive channels with consistent N* electrocouplings will offer evidence for the reliable evaluation of these fundamental quantities. [Preview Abstract] 
Monday, April 15, 2013 1:54PM  2:06PM 
R13.00003: Decay of the $\Lambda(1520)$ to $\Lambda\pi\pi$ via $\Sigma(1385)\pi$ Dao Ho, R.A. Schumacher, K. Moriya The $\Lambda(1520)$ $J^P = 3/2^$ hyperon may have a $\Sigma(1385)\pi$ substructure, as proposed in recent unitarized coupledchannel calculations [1]. While the branching fraction of the $\Lambda(1520) \to \Lambda\pi\pi$ is well known to be $0.10\pm0.01$, less well established is the relative branching fraction of the intermediate quasitwobody mode $\Lambda(1520) \to \Sigma(1385)\pi \to \Lambda\pi\pi$ compared to the direct $\Lambda\pi\pi$ mode. Previous measurements range from an upper limit of 0.44 to a value of 0.82. At CLAS a tagged real photon beam with highest energy at 3.8 GeV impinged upon a 40 cm LH2 target to reconstruct the parent hyperon using $\gamma p \to K^+ \Lambda(1520)$ from the detected kaon. Detection of both $\pi^+$ and $\pi^$, with a ground state $\Lambda$ in the overall missing mass, allowed complete reconstruction of the event kinematics. An incoherent Dalitztype analysis of the $\Lambda\pi\pi$ final state was used to determine the relative proportion. Simulation of the direct and twostep decay processes was used to match the data, with the branching fraction as a fitting parameter. Backgrounds were also modeled and included in the fits for the $\Lambda(1520)$ mass from 1.48 to 1.59 GeV.\\[4pt] [1] L. Roca et al., Phys. Rev. C73, 045208 (2006). [Preview Abstract] 
Monday, April 15, 2013 2:06PM  2:18PM 
R13.00004: The Search for a $\pi_1(1400)$ Exotic Meson in the $\gamma p\to\Delta^{++}\eta\pi^$ System Diane Schott Over twenty years ago QCDinspired models of hadronic states suggested the existence of mesons beyond the Naive Quark Model (NQM), which motivated a rigorous search for exotic mesons. The lightest of these states is the $\pi_1(1400)$ decaying to $\eta\pi^$ observed by experiment E852 at Brookhaven and the VES collaboration at IHEP. Photoproduction is predicted to favor production of a $J^{PC}=1^{+}$ gluonic excitation resulting in the increase of the ratio of $\pi_1$ to $a_2$ mesons. A Partial Wave Analysis was conducted on the reaction $\gamma p\to\Delta^{++}X\to p\pi^+\pi^(\eta)$, using the $\Delta^{++}$ to select the pion exchange. The analysis has shown the final spectra of the resonance decaying to $\eta\pi^$ to be dominated by the quantum state of $J^{PC}=2^{++}$ corresponding to the presence of the $a_2(1320)$. The $J^{PC}=1^{+}$ state, shows no structure in the intensity distribution. The phase difference between the $J^{PC}=1^{+}$ and $J^{PC}=2^{++}$ amplitudes show the interference between the two states. This is the first spinparity analysis of the $\eta\pi$ final state in photoproduction. [Preview Abstract] 
Monday, April 15, 2013 2:18PM  2:30PM 
R13.00005: Tetraquark bound states in the heavylight heavylight system Zachary Brown, Kostas Orginos A calculation of the interaction potential of two heavylight mesons in lattice QCD is used to study the existence of tetraquark bound states. The interaction potential of the tetraquark system is calculated on the lattice with 2+1 flavours of dynamical fermions with lattice interpolating fields constructed using \emph{colorwave} propagators. These propagators provide a method for constructing alltoall spatially smeared the interpolating fields, a technique which allows for a better overlap with the ground state wavefunction as well as reduced statistical noise. Potentials are extracted for 24 distinct channels, and are fit with a phenomenological nonrelativistic quark model potential, from which a determination of the existence of bound states is made via numerical solution of the two body radial Schr\"odinger equation. [Preview Abstract] 

R13.00006: ABSTRACT WITHDRAWN 
Monday, April 15, 2013 2:42PM  2:54PM 
R13.00007: A Mesonic Deuteron Analog Terrence Goldman, Richard SIlbar Using the Los Alamos Model Potential first applied to nuclear quark structure, we calculate the binding energy and quark structure of a Bmeson and a Dmeson. Aside from the spin differences, the larger than nucleon masses and complete absence of quark Pauli repulsive effects leads to a much smaller, but otherwise deuteronlike state, wherein pion exchange is present but not the dominant contribution to the binding of the state. [Preview Abstract] 
Monday, April 15, 2013 2:54PM  3:06PM 
R13.00008: A Meson Mass Formula and A TwoNucleon Potential from a Nonlinear $\lambda\phi^5$ Theory Mesgun Sebhatu An exact solution of a $\lambda\phi^5$ theory\footnote{P.B. Burt, Phys. Rev. Lett. 32,1080 (1974)} which is a special case of a class of nonlinear field theories developed by Burt\footnote{P.B. Burt, Quantum Mechanics and Nonlinear Waves,(Harwood 1981)} is used to construct a propagator that has poles at $M_n=(3n+1)m_\pi$ which is the neutral scalar meson mass formula. The propagator is then used to derive a solitary wave exchange twonucleon potential ($\lambda\phi^5$ SWEP) in the same manner as the derivation of a $\lambda\phi^4$ SWEP\footnote{M.Sebhatu, Nuovo Cimento, 16,463(1976)} and SG SWEP\footnote{M.Sebhatu, Lett. Nuovo Cimento, 16,463(1976)}. SWEPs have the virtue of describing twonucleaon interaction with the least number ($<$ 3) parameters. The $\lambda\phi^4$ is of a special interest because it yields a neutral scalar meson mass formula that reasonably agrees with know meson and predicts others that may exist. [Preview Abstract] 
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