Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session C6: Hadronic Physics |
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Sponsoring Units: DNP Chair: Alan Krisch, University of Michigan Room: 200 |
Saturday, April 5, 2014 1:30PM - 1:42PM |
C6.00001: Probing the Hadronic Weak Interaction using Polarized Slow Neutron Spin Rotation in L4He Eamon Anderson The NSR collaboration proposes to search for parity violation in n-4He by searching for a rotation of the plane of polarization of transversely polarized neutrons moving through the liquid. This observable is sensitive to a linear combination of weak amplitudes in the hadronic weak interaction which is orthogonal to previous measurements. An earlier measurement conducted at NIST reported $ d\theta/dz=[+1.7\pm9.1(\mathrm{stat})\pm1.4(\mathrm{sys.})]\times10^{-7}\sim$rad/m [1]. We will briefly discuss progress towards a $ 1\times10^{-8}$ sensitivity measurement.\\[4pt] [1] W.M. Snow et al, Phys. Rev. C \textbf{83} 2 2501 (2010). [Preview Abstract] |
Saturday, April 5, 2014 1:42PM - 1:54PM |
C6.00002: Radiative Transitions of the Y(4260) at BES Manuel Lara The recent discoveries of the so called ``XYZ'' states are beginning to open new possibilities for how quarks can interact and bind. Detailed studies of their decays are underway in many facilities like the BES detector which has collected a total of 2.092 fb$^{-1}$ of data at 4260, 4360, 4230 MeV to study the Y(4260). While the nature of the Y(4260) is still unknown two particularly important decay channels to study would be radiative decays to $\eta_c$ and $\chi_{c0}$, because their branching fraction ratio could be compared to existing E1/M1 branching fractions of conventional charmonium and to lattice qcd predictions. The prospects for measuring such transitions using data collected with the BES detector will be presented. [Preview Abstract] |
Saturday, April 5, 2014 1:54PM - 2:06PM |
C6.00003: Study of the spin-flavor structure of excited baryon masses from lattice QCD Ishara Fernando The known classification of excited baryons based on the dynamical symmetry group $SU(6)\times O(3)$ can be understood in the framework of the $1/N_c$ expansion[1]. The application to masses [2-5] based on the experimentally determined masses can now be extended to the case of baryon masses obtained in lattice QCD[6,7]. The work to be presented analyses the ground state as well as the excited multiplets $[70,1^-]$,$[56,0^+]$ and $[56,2^+]$. Mass relations which are valid up to corrections $1/N_c^2$, or $\frac{1}{N_c}(m_s-m_d)$,or $(m_s-m_d)^2$ are tested and conclusions on quark mass dependence of the effective mass operators and minimal sets of effective mass operators are obtained.\\[4pt] [1] R.F. Dashen, E.E. Jenkins, and A.V. Manohar Phys.Rev.D51,3697(1995). \\[0pt][2] C.E. Carlson, C.D. Carone, J.L. Goity, R.F. Lebed Phys.Rev.D59,114008 (1999). \\[0pt][3] J.L. Goity, C.L.Schat Phys.Rev.D66,114014 (1999). \\[0pt][4] J.L. Goity, C.L.Schat, N.N.Scoccola Phys.Lett.B564,83-89 (2003). \\[0pt][5] C.E. Carlson, C.D. Carone Phys.Lett.B484,260-266 (2000). \\[0pt][6] R.G. Edwards, J.J. Dudek, D.G. Richards, S.J. Wallace Phys.Rev.D84,074508 (2011). \\[0pt][7] R.G. Edwards, N.Mathur, D.G. Richards, S.J. Wallace Phys.Rev.D87,054506(2013). [Preview Abstract] |
Saturday, April 5, 2014 2:06PM - 2:18PM |
C6.00004: Single and double polarization asymmetries from deeply virtual $\pi^0$ production with a longitudinally polarized proton target Andrey Kim Deeply virtual exclusive meson production probes both the chiral-even generalized parton distributions (GPDs) and the chiral-odd transversity GPDs. The GPDs encode correlations of parton longitudinal momentum with transverse impact parameter as a function of the $x_B$ and $t$. The wide kinematic coverage of CLAS allowed measurements of exclusive $\pi^0$ electroproduction over the full azimuthal range. The resulting target and double-spin asymmetries were measured for the first time in the deep inelastic region. The experiment was carried out in Hall B at Jefferson Lab using a 6~GeV longitudinally polarized electron beam and a solid longitudinally polarized NH$_3$ target. All four final-state particles from the exclusive channel - electron, proton and two photons from $\pi^0$ decay - were identified. The azimuthal asymmetries in the hadronic center-of-mass system were fit, and their moments extracted. The data were compared to handbag-based calculations involving the contribution from both chiral-even and chiral-odd GPDs. The applicability of the formalism based on generalized parton distributions within the framework of the modified perturbative approach is discussed. [Preview Abstract] |
Saturday, April 5, 2014 2:18PM - 2:30PM |
C6.00005: Results from E07--013: Target Normal Single-Spin Asymmetry in Inclusive DIS Timothy Holmstrom The target normal spin asymmetry $A_y$ in deep inelastic scattering is predicted to be exactly zero in the Born approximation. Recent theoretical calculations that assume two photon exchange with one quark give asymmetries of order $10^{-4}$, while calculations that assume the two photons couple to different quarks give asymmetries of order $10^{-2}$. The first measurement of this asymmetry on the neutron was made in Hall A at Jefferson Lab (E07-013) by the polarized $^3$He collaboration using an inclusive deep-inelastic $n^{\uparrow}(e,e')$ reaction with a vertically polarized $^3$He target and a 5.8 GeV electron beam. Results of this measurement will be presented and interpretations of the result will be discussed. [Preview Abstract] |
Saturday, April 5, 2014 2:30PM - 2:42PM |
C6.00006: Search for Y(4260) $\rightarrow KK J/\psi$ at BESIII Daniel Bennett Many of the newly-discovered ``XYZ'' states offer unique insights into physics near the charmonium region, including the Y(4260) state, which is being studied with BESIII detector at the BEPCII collider in Beijing. $2813 \nolinebreak pb^{-1}$ of data has been collected at center of mass energy points ranging from 4.190 \nolinebreak MeV to 4.420 \nolinebreak MeV. In this analysis, we study the processes of $e^{+}e^{-} \rightarrow K^{+}K^{-} J/\psi$ and $K_{s}^{0} K_{s}^{0} J/\psi$ within this region, as well as compare these lineshapes to $e^{+}e^{-} \rightarrow \pi^{+} \pi^{-} J/\psi$. With these results, we can gain new information on the Y(4260) state and its possible non-$q\overline{q}$ interpretations. [Preview Abstract] |
Saturday, April 5, 2014 2:42PM - 2:54PM |
C6.00007: Concept for an Electron Ion Collider detector built around the BaBar solenoid Jin Huang A conceptual design for an Electron Ion Collider (EIC) detector, which builds upon the BaBar solenoid and the planned PHENIX detector upgrades, has been developed. This concept is designed for the PHENIX interaction point on the proposed eRHIC collider, which adds an electron beam to the current RHIC collider to provide polarized e+p/e+A collisions. The PHENIX collaboration is planning a detector upgrade before the EIC era, which consists of large acceptance electromagnetic and hadronic calorimetry and tracking detectors built around the superconducting solenoid recently acquired from the decommissioned BaBar experiment at SLAC. In this EIC detector design, we utilize this upgrade and propose to add new detectors for measurements of a comprehensive EIC physics program. In this talk, we will give an overview for the detector design and its physics capabilities. Update on performance studies will also be discussed. [Preview Abstract] |
Saturday, April 5, 2014 2:54PM - 3:06PM |
C6.00008: Fermion Mass Generation without a Chiral condensate Venkitesh Ayyar, Shailesh Chandrasekharan While it is well known that massless fermions can become massive due to interactions, it is usually believed that this requires the formation of a fermion bilinear condensate that can act as the mass term for the fermions. Using a strong coupling argument within a lattice four-fermion model, we propose that, in principle, fermions may be able to acquire a mass without the formation of any such condensate. Using Monte Carlo calculations in three Euclidean space-time dimensions, we show evidence for this surprising possibility and argue that this massive strong coupling phase could also have an interesting continuum limit. [Preview Abstract] |
Saturday, April 5, 2014 3:06PM - 3:18PM |
C6.00009: Precise Measurement of the Mass of the $\tau$ Lepton Tao Luo An optimized energy scan near the $\tau$ pair production threshold has been performed using the BESIII detector. About $24$ pb$^{-1}$ of data, distributed over four scan points, was collected. The $\tau$ mass is determined directly from the threshold behavior of the $\tau$ pair production cross section in the $e^{+}e^{-}$ collisions. The key question in the measurement is how to determine the beam energy precisely. Here the beam energy measurement system (BEMS) for BEPC-II is used to determine the beam energy. The relative systematic uncertainty of the electron and positron beam energy determination in our experiment is estimated as $2\times10^{-5}$; the relative uncertainty of the beam's energy spread is about $6\%$. This analysis is based on the combined data from the $ee$, $e\mu$, $eh$, $\mu\mu$, $\mu h$, $hh$, $e\rho$, $\mu\rho$ and $\pi\rho$ final states, where $h$ denotes a charged $\pi$ or $K$. The mass of the $\tau$ lepton is measured as \begin{eqnarray} \label{finaltaumass} m_{\tau} = 1776.91\pm0.12~^{+0.09}_{-0.12} ~\mbox{MeV/c$^2$} \end{eqnarray} which is consistent with results from any other groups included by the Particle Data Group, but has the smallest uncertainty. [Preview Abstract] |
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