Mon·Jun 1, 2015Monday·June 1, 2015

1. 01*

   Azimuthal anisotropy in U+U and Au+Au collisions at RHIC

   STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · J. Alford · A. Aparin · D. Arkhipkin · E. C. Aschenauer · G. S. Averichev · V. Bairathi and 320 other authors

   Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, $v_2\{2\}$ and $v_2\{4\}$, for charged hadrons from U+U collisions at $\sqrt{s_{\mathrm{NN}}}$ = 193 GeV and Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV. Nearly fully overlapping collisions are selected based on the amount of energy deposited by spectators in the STAR Zero Degree Calorimeters (ZDCs). Within this sample, the observed dependence of $v_2\{2\}$ on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. An initial-state model with gluon saturation describes the slope of $v_2\{2\}$ as a function of multiplicity in central collisions better than one based on Glauber with a two-component multiplicity model.

   nucl-exnucl-thPRL(2015)·169 citations
2. 02*

   Precise Determination of the Deuteron Spin Structure at Low to Moderate $Q^2$ with CLAS and Extraction of the Neutron Contribution

   N. Guler🇺🇸 · R.G. Fersch🇺🇸 · S.E. Kuhn🇺🇸 · P. Bosted🇺🇸 · K.A. Griffioen🇺🇸 · C. Keith🇺🇸 · R. Minehart🇺🇸 · Y. Prok🇺🇸 · K.P. Adhikari🇺🇸 · D. Adikaram🇺🇸 · M.J. Amaryan🇺🇸 · M.D. Anderson🇬🇧 and 117 other authors

   We present the final results for the deuteron spin structure functions obtained from the full data set collected with Jefferson Lab's CLAS in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.8 GeV were scattered from deuteron (${}^{15}$ND${}_3$) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double spin asymmetry, the virtual photon absorption asymmetry $A_1^d$ and the polarized structure function $g_1^d$ were extracted over a wide kinematic range (0.05 GeV${}^2<Q^2<$ 5 GeV${}^2$ and 0.9 GeV $<W<$ 3 GeV). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions $A_1^n$ and $g_1^n$ of the (bound) neutron, which are so far unknown in the resonance region, $W<2$ GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large $x$, a better understanding of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the Operator Product Expansion.

   nucl-exPRC(2015)·56 citations
3. 03*

   First measurement of target and beam-target asymmetries in the $\gamma p\to {\pi }^0\eta p$ reaction

   J. R. M. Annand🇬🇧 · H. J. Arends🇩🇪 · R. Beck🇩🇪 · N. Borisov🇷🇺 · A. Braghieri🇮🇹 · W. J. Briscoe🇺🇸 · S. Cherepnya🇷🇺 · C. Collicott🇨🇦 · S. Costanza🇮🇹 · E. J. Downie🇩🇪 · M. Dieterle🇨🇭 · A. Fix🇷🇺 and 55 other authors

   The first data on target and beam-target asymmetries for the $\gamma p\to {\pi }^0\eta p$ reaction at photon energies from 1050 up to 1450 MeV are presented. The measurements were performed using the Crystal Ball and TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The general assumption that the reaction is dominated by the $\Delta 3/2^{-}$ amplitude is confirmed. The data are in particular sensitive to small contributions from other partial waves.

   nucl-exhep-exnucl-thPRC(2015)·13 citations
4. 04*

   \b{eta}-delayed three-proton decay of 31Ar

   A.A. Lis · C. Mazzocchi🇵🇱 · W. Dominik🇵🇱 · Z. Janas🇵🇱 · M. Pfützner🇬🇧 · M. Pomorski🇵🇱 · L. Acosta🇮🇹 · S. Baraeva · E. Casarejos🇪🇸 · J. Duénas-Díaz · V. Dunin🇷🇺 · J. M. Espino🇪🇸 and 29 other authors

   The beta decay of 31Ar, produced by fragmentation of a 36Ar beam at 880 MeV/nucleon, was investigated. Identified ions of 31Ar were stopped in a gaseous time projection chamber with optical readout allowing to record decay events with emission of protons. In addition to \b{eta}-delayed emission of one and two protons we have clearly observed the beta-delayed three-proton branch. The branching ratio for this channel in 31Ar is found to be 0.07(2)%.

   nucl-exPRC(2015)·23 citations
5. 05*

   Fission barriers heights in A$\sim$ 200 mass region

   K. Mahata🇮🇳

   Statistical model analysis has been carried out for $p$ and $\alpha$ induced fission reactions using a consistent description for fission barrier and level density in A $\sim$ 200 mass region. A continuous damping of shell correction with excitation energy have been considered. Extracted fission barriers agree well with the recent microscopic-macroscopic model. The shell corrections at the saddle point were found to be not significant.

   nucl-exnucl-thPramana(2015)·3 citations
6. 06*

   NEUT development for T2K and relevance of updated 2p2h models

   Callum Wilkinson (for the T2K Collaboration)🇬🇧

   The MiniBooNE large axial-mass anomaly has motivated the development of new theoretical Charged Current Quasi-Elastic (CCQE) cross-section models in recent years. These proceedings review the development of the neutrino simulation generator NEUT to incorporate these more sophisticated CCQE models, including multi-nucleon interaction (2p2h) effects. The fit results on the MINER$\nu$A and MiniBoone data are used to tune neutrino interaction models in NEUT and develop a default cross-section model for T2K.

   ↳ hep-exhep-phnucl-exPoS(2015)·6 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.