Tue·Jul 1, 2014Tuesday·July 1, 2014

1. 01*

   Azimuthal anisotropy in U+U collisions at STAR

   Hui Wang🇺🇸 · Paul Sorensen (STAR Collaboration)🇺🇸

   The azimuthal anisotropy of particle production is commonly used in high-energy nuclear collisions to study the early evolution of the expanding system. The prolate shape of uranium nuclei makes it possible to study how the geometry of the colliding nuclei affects final state anisotropies. It also provides a unique opportunity to understand how entropy is produced in heavy ion collisions. In this paper, the two- and four- particle cumulant $v_2$ ($v_2\{2\}$ and $v_2\{4\}$) from U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeters are used to select very central collisions. Differences were observed between the multiplicity dependence of $v_2\{2\}$ for most central Au+Au and U+U collisions. The multiplicity dependence of $v_2\{2\}$ in central collisions were compared to Monte Carlo Glauber model predictions and it was seen that this model cannot explain the present results.

   nucl-exNPA(2014)·21 citations
2. 02*

   Exclusive J/$\psi$ photoproduction off protons in ultra-peripheral p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   We present the first measurement at the LHC of exclusive J/$\psi$ photoproduction off protons, in ultra-peripheral proton-lead collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. Events are selected with a dimuon pair produced either in the rapidity interval, in the laboratory frame, $2.5<y<4$ (p-Pb) or $-3.6<y<-2.6$ (Pb--p), and no other particles observed in the ALICE acceptance. The measured cross sections $\sigma (\gamma +\mathrm{p}\to J/\psi +\mathrm{p})$ are 33.2 $\pm$ 2.2 (stat) $\pm$ 3.1 (syst) $\pm$ 0.7 (theo) nb in p-Pb and 284 $\pm$ 36 (stat) ${}_{-32}^{+27}$ (syst) $\pm$ 26 (theo) nb in Pb-p collisions. We measure this process up to about 700 GeV in the $\gamma \mathrm{p}$ centre-of-mass, which is a factor of two larger than the highest energy studied at HERA. The data are consistent with a power law dependence of the $J/\psi$ photoproduction cross section in $\gamma \mathrm{p}$ energies from about 20 to 700 GeV, or equivalently, from Bjorken-$x$ between $\sim 2\times 10^{-2}$ to $\sim 2\times 10^{-5}$, thus indicating no significant change in the gluon density behaviour of the proton between HERA and LHC energies.

   nucl-exhep-exPRL(2014)·259 citations
3. 03*

   Similarity between nuclear rainbow and meteorological rainbow -- evidence for nuclear ripples

   S. Ohkubo🇯🇵 · Y. Hirabayashi🇯🇵

   We present evidence for the nuclear ripples superimposed on the Airy structure of the nuclear rainbow, which is similar to the meteorological rainbow. The mechanism of the nuclear ripples is also similar to that of the meteorological rainbow, which is caused by the interference between the externally reflective waves and refractive waves. The nuclear ripple structure was confirmed by analyzing the elastic angular distribution in ${}^{16}$O+${}^{12}$C rainbow scattering at $E_L$=115.9 MeV using the coupled channels method by taking account of coupling to the excited states of ${}^{12}$C and ${}^{16}$O with a double folding model derived from a density-dependent effective nucleon-nucleon force with realistic wave functions for ${}^{12}$C and ${}^{16}$O. The coupling to the excited states plays the role of creating the external reflection.

   ↳ nucl-thnucl-exphysics.hist-phphysics.opticsPRC(2014)·12 citations
4. 04*

   Parametrization of gamma-ray production cross-sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies

   Ervin Kafexhiu🇩🇪 · Felix Aharonian🇮🇪 · Andrew M. Taylor🇮🇪 · Gabriela S. Vila🇦🇷

   Using publicly available Monte Carlo codes as well as compilation of published data on p--p interactions for proton kinetic energy below 2 GeV, we parametrize the energy spectra and production rates of $\gamma$-rays by simple but quite accurate ($\le 20\%$) analytical expressions in a broad range from the kinematic threshold to PeV energies.

   ↳ astro-ph.HEnucl-exPRD(2014)·404 citations
5. 05*

   Towards a Pion Generalized Parton Distribution Model from Dyson-Schwinger Equations

   C. Mezrag🇫🇷 · H. Moutarde🇫🇷 · J. Rodríguez-Quintero🇪🇸 · F. Sabatié🇫🇷

   We compute the pion quark Generalized Parton Distribution H and quark Double Distributions F and G in a coupled Bethe-Salpeter and Dyson-Schwinger approach in terms of quark flavors or isospin states. We use simple analytic expressions inspired by the numerical resolution of Dyson-Schwinger and Bethe-Salpeter equations. We explicitly check the support and polynomiality properties, and the behavior under charge conjugation or time invariance of our model. We obtain analytic expressions for the pion Double Distributions and Generalized Parton Distribution at vanishing pion momentum transfer at a low scale. Our model compares very well to experimental pion form factor or Parton Distribution Function data. This paper is the first stage of a GPD-modeling program which will be pursued by incorporating more realistic solutions of the Bethe-Salpeter and Dyson-Schwinger equations.

   ↳ hep-phhep-exnucl-exnucl-th23 citations
6. 06*

   Predicting exotic molecular states composed of nucleon and P-wave charmed meson

   Rui Chen🇨🇳 · Zhi-Feng Sun🇨🇳 · Xiang Liu🇨🇳 · S. M. Gerasyuta🇷🇺

   In this work, we study the interaction between a nucleon and a $P$-wave charmed meson in the $T$ doublet by exchanging a pion. Our calculations indicate that a nucleon and a $P$-wave charmed meson with $J^P=0^{+}$ or $J^P=1^{+}$ in the $T$ doublet can form bound states. We propose the experimental search for these exotic molecular states near the $D_1(2420)N$ and $D_2^{\ast }(2460)N$ thresholds, where Belle, LHCb and the forthcoming Belle II have the discovery potential for them.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2014)·10 citations
7. 07*

   Nuclear force and the EMC effect

   Rong Wang🇨🇳 · Xurong Chen🇨🇳

   A linear correlation is shown quantitatively between the magnitude of the EMC effect measured in electron deep inelastic scattering (DIS) and the nuclear residual strong interaction energy (RSIE) obtained from nuclear binding energy subtracting the Coulomb energy contribution. This phenomenological relationship is used to extract the size of in-medium correction (IMC) effect on deuteron and to predict the EMC slopes $|d{R}_{EMC}/dx|$ of various nuclei. We further investigate the correlations between RSIE and other quantities which are related to the EMC effect. The observed correlations among RSIE, EMC slope and SRC ratio $R_{2N}{N}_{total}/N_{np{(}^3{S}_1)}$ imply that the local nuclear environment drives the modification of quark distributions.

   ↳ nucl-thnucl-exPLB(2015)·10 citations
8. 08*

   Recent results of gluon and sea quark polarization measurements in polarized proton-proton collisions at STAR

   Xuan Li (STAR Collaboration)🇺🇸

   The STAR experiment at RHIC is carrying out a comprehensive high-energy spin physics program to understand the internal structure and dynamics of the proton in polarized proton-proton collisions at $\sqrt{s}=200$ GeV and $\sqrt{s}=500/510$ GeV. STAR has the capability, with nearly full azimuthal coverage, to reconstruct leptons, hadrons and jets in the mid-rapidity region ($|\eta |<1$). The results for inclusive jet longitudinal double spin asymmetries taken during the 2009 RHIC run indicate the first non-zero gluon contribution ($\Delta g(x,Q^2)/g(x,Q^2)$) to the proton spin for $0.05<x<1$ (Bjorken-x: momentum fraction of partons). Recent longitudinal single-spin asymmetry measurements of $W^{+/-}$ bosons at $\sqrt{s}=500/510$ GeV in polarized proton-proton collisions provide a direct probe of the polarized anti-u and anti-d quark distributions ($\Delta \bar{u}(x,Q^2)$, $\Delta \bar{d}(x,Q^2)$). These results better constrain the polarized gluon and sea quark distributions of the proton in the RHIC sensitive kinematic region. Future measurements with continuing high energy polarized proton-proton run at RHIC and detector upgrade will explore the gluonic contribution to the proton spin in extended range.

   ↳ hep-exnucl-exJ.Phys.Conf.Ser.(2014)·0 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.