Wed·Mar 29, 2017Wednesday·March 29, 2017

1. 01*

   Jet-hadron correlations relative to the event plane at the LHC with ALICE

   Joel Mazer (for the ALICE collaboration)🇺🇸

   The hot, dense and strongly interacting medium known as the Quark Gluon Plasma (QGP) is produced in relativistic heavy-ion collisions at the Large Hadron Collider (LHC). Early in the collisions, quarks and gluons from the incoming nuclei collide to produce high momentum partons which fragment into collimated sprays of hadrons called "jets". In pp collisions, jet production is well understood within the framework of perturbative QCD and acts as a rigorous baseline measurement for jet quenching measurements. Using pp as a reference, we can compare to heavy-ion collision systems, and study the modification of the $p_T$ or angular distributions of jet fragments. A recently developed background subtraction method to remove the complex, flow dominated, heavy-ion background will be used in this analysis. Azimuthal angular correlations of charged hadrons with respect to the axis of a full (charged + neutral) reconstructed 'trigger' jet in Pb--Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV in ALICE will be presented here. The analysis of angular correlations for different orientations of the trigger relative to the event plane allows for the study of the path length dependence of medium modifications to jets. The status of studies of the event plane dependence of angular correlations will be presented.

   nucl-exJ.Phys.Conf.Ser.(2017)·5 citations
2. 02*

   PHENIX results on direct photon-hadron correlations

   Huijun Ge (for the PHENIX collaboration)🇺🇸

   Direct photon-hadron correlations are a golden channel to study parton in-medium energy loss in QGP. The modification of the effective fragmentation function for the away-side jet can be measured by comparing integrated away-side yields of direct photon-hadron pairs in heavy ion collisions to those in p+p. We measured per-trigger-yield of associated hadrons in Au+Au collisions and observed that there is a suppression compared to p+p for higher momentum fraction ($z_T$) hadrons. This can be explained by the opacity of the hot medium: energetic partons from the initial hard scattering lose energy while traversing it. A yield enhancement on the other hand has been found at low $z_T$ (high $\xi$). Medium response is likely to be responsible for the enhanced production of these lower momentum particles. The same measurement is done in d+Au collisions and the result suggests that no modification to the fragmentation function is observed, given the current uncertainties.

   nucl-exNucl.Part.Phys.Proc.(2017)·10 citations
3. 03*

   Core-excitation effects in ${}^{20}\mathrm{O}(d,p){}^{21}\mathrm{O}$ transfer reactions: Suppression or enhancement?

   A. Deltuva🇱🇹 · D. Jurčiukonis🇱🇹 · E. Norvaišas🇱🇹

   ${}^{20}\mathrm{O}(d,p){}^{21}\mathrm{O}$ transfer reactions are described using momentum-space Faddeev-type equations for transition operators and including the vibrational excitation of the ${}^{20}\mathrm{O}$ core. The available experimental cross section data at 10.5 MeV/nucleon beam energy for the ${}^{21}\mathrm{O}$ ground state ${\frac{5}{2}}^{+}$ and excited state ${\frac{1}{2}}^{+}$ are quite well reproduced by our calculations including the core excitation. Its effect can be roughly simulated reducing the single-particle cross section by the corresponding spectroscopic factor. Consequently, the extraction of the spectroscopic factors taking the ratio of experimental data and single-particle cross section at this energy is a reasonable procedure. However, at higher energies core-excitation effects are much more complicated and have no simple relation to spectroscopic factors. We found that core-excitation effects are qualitatively very different for reactions with the orbital angular momentum transfer $\ell =0$ and $\ell =2$, suppressing the cross sections for the former and enhancing for the latter, and changes the shape of the angular distribution in both cases. Furthermore, the core-excitation effect is a result of a complicated interplay between its contributions of the two- and three-body nature.

   ↳ nucl-thnucl-exPLB(2017)·11 citations
4. 04*

   Cross section and transverse single-spin asymmetry of muons from open heavy-flavor decays in polarized $p$+$p$ collisions at $\sqrt{s}=200$ GeV

   C. Aidala · N.N. Ajitanand · Y. Akiba · R. Akimoto · J. Alexander · M. Alfred · K. Aoki · N. Apadula · H. Asano · E.T. Atomssa · T.C. Awes · C. Ayuso and 426 other authors

   The cross section and transverse single-spin asymmetries of ${\mu }^{-}$ and ${\mu }^{+}$ from open heavy-flavor decays in polarized $p$+$p$ collisions at $\sqrt{s}=200$ GeV were measured by the PHENIX experiment during 2012 at the Relativistic Heavy Ion Collider. Because heavy-flavor production is dominated by gluon-gluon interactions at $\sqrt{s}=200$ GeV, these measurements offer a unique opportunity to obtain information on the trigluon correlation functions. The measurements are performed at forward and backward rapidity ($1.4<|y|<2.0$) over the transverse momentum range of $1.25<p_T<7$ GeV/$c$ for the cross section and $1.25<p_T<5$ GeV/$c$ for the asymmetry measurements. The obtained cross section is compared to a fixed-order-plus-next-to-leading-log perturbative-quantum-chromodynamics calculation. The asymmetry results are consistent with zero within uncertainties, and a model calculation based on twist-3 three-gluon correlations agrees with the data.

   ↳ hep-exnucl-exPRD(2017)·34 citations
5. 05*

   Elliptic flows of light nuclei

   Xuejiao Yin🇨🇳 · Che Ming Ko🇺🇸 · Yifeng Sun🇺🇸 · Lilin Zhu🇨🇳

   Using the coalescence model based on nucleons from a blast-wave model with its parameters fitted to the measured proton transverse momentum spectrum and elliptic flow in heavy ion collisions at the Relativistic Heavy Ion Collider, we study the elliptic flows of light nuclei in these collisions. We find that to describe the measured elliptic flows of deuterons (anti-deuterons) and tritons (helium-3) requires that the emission source for nucleons of high transverse momentum is more elongated along the reaction plane than in the perpendicular direction. Our results thus suggest that the elliptic flows of light nuclei can be used to study the nucleon emission source in relativistic heavy ion collisions.

   ↳ nucl-thnucl-exPRC(2017)·19 citations
6. 06*

   Luneburg-lens-like structural Pauli attractive core of nuclear force at short distances

   Shigeo Ohkubo🇯🇵

   The nuclear force has been understood to have a repulsive core at short distances, similar to a molecular force, since Jastrow proposed it in 1951. The existence of the repulsion was experimentally confirmed from the proton-proton scattering 1S_0 phase shift, which becomes negative beyond 230 MeV. This repulsion is essential for preventing the nucleon-nucleon system from collapsing by attraction. The origin of the repulsion has been considered to be due to the Pauli principle, similar to the repulsion originally revealed in alpha-alpha scattering, in many studies including recent lattice QCD calculations. On the other hand, very recently it was shown that an inter-nuclear potential including alpha-alpha interactions has a Luneburg-lens-like attraction at short distances rather than repulsion. We show that the nuclear force with an attractive potential at short distances that reproduces the experimental phase shifts well has a Luneburg-lens-like structural Pauli attractive core (SPAC) at short distances and acts as apparent repulsion. The apparent repulsion is caused by the deeply embedded unobservable Pauli forbidden state similar to nucleus-nucleus potentials.

   ↳ nucl-thhep-phnucl-exPRC(2017)·3 citations
7. 07*

   A Glimpse of Gluons through Deeply Virtual Compton Scattering on the Proton

   M. Defurne🇫🇷 · A. Martì Jiménez-Argüello🇫🇷 · Z. Ahmed🇺🇸 · H. Albataineh🇺🇸 · K. Allada🇺🇸 · K. A. Aniol🇺🇸 · V. Bellini🇮🇹 · M. Benali🇫🇷 · W. Boeglin🇺🇸 · P. Bertin🇫🇷 · M. Brossard🇫🇷 · A. Camsonne🇺🇸 and 82 other authors

   The proton is composed of quarks and gluons, bound by the most elusive mechanism of strong interaction called confinement. In this work, the dynamics of quarks and gluons are investigated using deeply virtual Compton scattering (DVCS): produced by a multi-GeV electron, a highly virtual photon scatters off the proton which subsequently radiates a high energy photon. Similarly to holography, measuring not only the magnitude but also the phase of the DVCS amplitude allows to perform 3D images of the internal structure of the proton. The phase is made accessible through the quantum-mechanical interference of DVCS with the Bethe-Heitler (BH) process, in which the final photon is emitted by the electron rather than the proton. We report herein the first full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the high energy regime where the scattering process is expected to occur off a single quark in the proton, these accurate measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

   ↳ hep-exhep-phnucl-exNature Commun.(2017)·85 citations
8. 08*

   Event-by-event charge separation in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV with ALICE at the LHC

   Sonia Parmar (for the ALICE collaboration)🇮🇳

   Relativistic heavy-ion collisions provide a unique opportunity to search for parity violation in non-central collisions. This could lead to charge separation perpendicular to the reaction plane. An event-by-event measurement of charge separation effect in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV using Sliding Dumbbell Method (SDM) is discussed in this article.

   ↳ hep-exnucl-exSpringer Proc.Phys.(2018)·1 citation

* 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.