Fri·Oct 2, 2015Friday·October 2, 2015

1. 01*

   Longitudinal Spin Physics at RHIC and a Future eRHIC

   Brian Page🇺🇸

   Recent highlights from the spin program at the Relativistic Heavy Ion Collider (RHIC), focusing on the gluon contribution to the proton spin and the polarization of the light flavor sea, are presented. The impact of these data on recent global fits by the DSSV and NNPDF groups is also discussed. Finally, this note examines the constraints on the longitudinal spin structure of the proton which would be possible with a proposed eRHIC facility.

   nucl-exnucl-th1 citation
2. 02*

   Energy dependence of fluctuations in p+p and Be+Be collisions from NA61/SHINE

   Evgeny Andronov (for the NA61/SHINE Collaboration)🇷🇺

   The main aims of the NA61/SHINE experiment are to discover the critical point of strongly interacting matter and to study properties of the onset of deconfinement. For this goal a two dimensional scan of the phase diagram (T-${\mu }_B$) is being performed at the SPS with measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. It is expected that fluctuations of various dynamical quantities will increase close to the critical point. In this contribution recent results of measurements of fluctuations in p+p and Be+Be collisions at SPS energies are presented as well as comparisons with model predictions and corresponding data of other experiments are discussed.

   nucl-exJ.Phys.Conf.Ser.(2016)·2 citations
3. 03*

   Symmetry energy of cold nucleonic matter within a relativistic mean field model encapsulating effects of high momentum nucleons induced by short-range correlations

   Bao-Jun Cai🇺🇸 · Bao-An Li🇺🇸

   Significant progress has been made recently in constraining the isospin-dependent parameters characterizing the SRC (short-range correlation)-modified single-nucleon momentum distribution in neutron-rich nucleonic matter using both experimental data and microscopic model calculations. Using the constrained single-nucleon momentum distribution in a nonlinear relativistic mean field (RMF) model, we study the equation of state (EOS) of asymmetric nucleonic matter (ANM), especially the density dependence of nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$. Firstly, as a test of the model, the average nucleon kinetic energy extracted recently from electron-nucleus scattering experiments using a neutron-proton dominance model is well reproduced by the RMF model incorporating effects of the SRC-induced high momentum nucleons, while it is significantly under predicted by the RMF model using a step function for the single-nucleon momentum distribution as in free Fermi gas (FFG) models. Secondly, the kinetic symmetry energy of quasi-nucleons is found to be $E_{\mathrm{sym}}^{\mathrm{kin}}({\rho }_0)=-16.94\pm 13.66\mathrm{MeV}$ which is dramatically different from the prediction of $E_{\mathrm{sym}}^{\mathrm{kin}}({\rho }_0)\approx 12.5$ MeV by FFG models at nuclear matter saturation density ${\rho }_0=0.16{\mathrm{fm}}^{-3}$. Thirdly, comparing the RMF calculations with and without the high momentum nucleons using two sets of model parameters both reproducing identically all empirically constraints on the EOS of symmetric nuclear matter (SNM) and the symmetry energy of ANM at ${\rho }_0$, the SRC-modified single-nucleon momentum distribution is found to make the $E_{\mathrm{sym}}(\rho )$ more concave around ${\rho }_0$ by softening it significantly at both sub-saturation and supra-saturation densities, leading to an isospin-dependent incompressibility of ANM in better agreement with existing experimental data.

   ↳ nucl-thastro-ph.SRnucl-exPRC(2016)·78 citations
4. 04*

   Near-threshold $J/\psi$ photoproduction off nuclei

   E. Ya. Paryev🇷🇺 · Yu. T. Kiselev🇷🇺

   We study the $J/\psi$ photoproduction from nuclei near the kinematic threshold within the first collision model, based on the nuclear spectral function, for incoherent primary photon--nucleon charmonium creation processes. The model takes into account the final $J/\psi$ absorption, target nucleon binding and Fermi motion, the formation length of $J/\psi$ mesons as well as the effect of their nuclear mean-field potential on these processes. We calculate the A dependences of the absolute and relative (transparency ratio) charmonium yields as well as its absolute and relative excitation functions within the different scenarios for the $J/\psi N$ absorption cross section, for the $J/\psi$ formation length and for $J/\psi$ in-medium modification. We demonstrate that the studied observables, on the one hand, are not practically affected by the charmonium formation length and mass shift effects and, on the other hand, they are appreciably sensitive to the genuine $J/\psi N$ absorption cross section at above threshold beam energies, which means that these observables can be useful to help determine the $J/\psi N$ absorption cross section from the comparison of the results of our calculations with the future data from the experiments in the Hall C at the upgraded up to 12 GeV CEBAF facility. We also show that the absolute and relative excitation functions for $J/\psi$ subthreshold production in $\gamma A$ reactions reveal some sensitivity to adopted in-medium modification scenarios for $J/\psi$ mesons. Therefore, such observables, measured in the subthreshold energy domain, may be an important tool to get valuable information on the charmonium in-medium properties in cold nuclear matter.

   ↳ nucl-thnucl-ex4 citations
5. 05*

   Multiplicity and transverse momentum fluctuations in inelastic proton-proton interactions at the CERN Super Proton Synchrotron

   NA61/SHINE Collaboration: A. Aduszkiewicz🇵🇱 · Y. Ali🇵🇱 · E. Andronov🇷🇺 · T. Anticic🇭🇷 · N. Antoniou🇬🇷 · B. Baatar🇷🇺 · F. Bay🇨🇭 · A. Blondel🇨🇭 · J. Blumer🇩🇪 · M. Bogomilov🇧🇬 · A. Bravar🇨🇭 · J. Brzychczyk🇵🇱 and 120 other authors

   Measurements of multiplicity and transverse momentum fluctuations of charged particles were performed in inelastic p+p interactions at 20, 31, 40, 80 and 158 GeV/c beam momentum. Results for the scaled variance of the multiplicity distribution and for three strongly intensive measures of multiplicity and transverse momentum fluctuations \$\Delta[P_{T},N]\$, \$\Sigma[P_{T},N]\$ and \$\Phi_{p_T}\$ are presented. For the first time the results on fluctuations are fully corrected for experimental biases. The results on multiplicity and transverse momentum fluctuations significantly deviate from expectations for the independent particle production. They also depend on charges of selected hadrons. The string-resonance Monte Carlo models EPOS and UrQMD do not describe the data. The scaled variance of multiplicity fluctuations is significantly higher in inelastic p+p interactions than in central Pb+Pb collisions measured by NA49 at the same energy per nucleon. This is in qualitative disagreement with the predictions of the Wounded Nucleon Model. Within the statistical framework the enhanced multiplicity fluctuations in inelastic p+p interactions can be interpreted as due to event-by-event fluctuations of the fireball energy and/or volume.

   ↳ hep-exnucl-exEPJC(2016)·80 citations
6. 06*

   OPERA neutrino oscillation search: status and perspectives

   Giuliana Galati🇮🇹

   OPERA is a long-baseline experiment at the Gran Sasso laboratory (LNGS) designed to search for ${\nu }_{\mu }\to {\nu }_{\tau }$ oscillations in appearance mode. OPERA took data from 2008 to 2012 with the CNGS neutrino beam from CERN. The data analysis is ongoing, with the goal of establishing ${\nu }_{\tau }$ appearance with high significance and improving the sensitivity to the sterile neutrino search in the ${\nu }_{\mu }$ $\to$ ${\nu }_e$ appearance channel. Current results will be presented and perspectives discussed.

   ↳ hep-exnucl-exphysics.ins-det0 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.