Wed·Aug 17, 2011Wednesday·August 17, 2011

1. 01*

   Helicity Asymmetry in gamma p -> pi+ n with FROST

   Steffen Strauch (for the CLAS Collaboration)🇺🇸

   The main objective of the FROST experiment at Jefferson Lab is the study of baryon resonances. The polarization observable E for the reaction gamma p to pi+n has been measured as part of this program. A circularly polarized tagged photon beam with energies from 0.35 to 2.35 GeV was incident on a longitudinally polarized frozen-spin butanol target. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer. Preliminary polarization data agree fairly well with present SAID and MAID partial-wave analyses at low photon energies. In most of the covered energy range, however, significant deviations are observed. These discrepancies underline the crucial importance of polarization observables to further constrain these analyses.

   nucl-exAIP Conf.Proc.(2012)·7 citations
2. 02*

   Comment on "High-Precision Determination of the Electric and Magnetic Form Factors of the Proton"

   J. Arrington🇺🇸

   In a recent Letter, Bernauer, et al. present fits to the proton electromagnetic form factors, GEp(Q^2) and GMp(Q^2), along with extracted proton charge and magnetization radii based on large set of new, high statistical precision (<0.2%) cross section measurements. The Coulomb corrections they apply differ dramatically from more modern and complete calculations, implying significant error in their final results.

   nucl-exnucl-thPRL(2011)·35 citations
3. 03*

   BESIII: "charming" physics at an e${}^{+}$e${}^{-}$ collider machine

   Johan Messchendorp (for the BESIII collaboration)🇳🇱

   Despite the successes of the standard model, the non-perturbative dynamics of the strong interaction are not fully understood yet. Charmonium spectroscopy serves as an ideal tool to shed light on the dynamics of the strong interaction such as quark confinement and the generation of hadron masses. The BESIII collaboration studies extensively the strong interaction and various aspects that could shed light on physics beyond the standard model via copious e${}^{+}$e${}^{-}$ collisions at the BESIII/BEPCII facility in Beijing, China, in the charmonium mass regime. We present a few of the recent results with the emphasis on charmonium spectroscopy studies using 106$\times 10^6$ ${\psi }^{\prime }$ events.

   ↳ hep-exnucl-exPoS(2011)·2 citations
4. 04*

   Transverse electron scattering response function of 3He in the quasi-elastic peak region and beyond with Delta isobar degrees of freedom

   Luping Yuan🇮🇹 · Winfried Leidemann🇮🇹 · Victor D. Efros🇮🇹 · Giuseppina Orlandini🇮🇹 · Edward L. Tomusiak🇨🇦

   The 3He transverse electron scattering response function R_T(q,omega) is calculated in the quasi-elastic peak region and beyond for momentum transfers q = 500, 600 and 700 MeV/c. Distinct from our previous work for these kinematics where we included meson exchange currents and relativistic corrections we now additionally include Delta isobar currents (Delta-IC). The Delta-IC contribution increases the quasi-elastic peak height by about 5% and leads to an excellent agreement with experimental data in the whole peak region. In addition it is shown that effects due to the three-nucleon force largely cancel those due to the Delta-IC in the peak region. Finally, we have found that Delta-IC are important for three-body break-up reactions in the so-called dip region. This could explain why in a previous study of such a reaction, where Delta degrees of freedom were not included, no agreement between experimental and theoretical results could be obtained.

   ↳ nucl-thnucl-exPLB(2011)·11 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.