Tue·May 3, 2016Tuesday·May 3, 2016

1. 01*

   Beam energy dependence of pseudorapidity distributions of charged particles produced in heavy-ion collisions at RHIC and LHC energies

   Sumit Basu🇮🇳 · Tapan K. Nayak🇮🇳 · Kaustuv Datta🇺🇸

   Heavy-ion collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN probe matter at extreme conditions of temperature and energy density. Most of the global properties of the collisions can be extracted from the measurements of charged particle multiplicity and pseudorapidity ($\eta$) distributions. We have shown that the available experimental data on beam energy and centrality dependence of \Eta-distributions in heavy-ion (Au+Au or Pb+Pb) collisions from \sNN=7.7 GeV to 2.76 TeV are reasonably well described by the AMPT model, which is used for further exploration. The nature of the \Eta-distributions has been described by a double Gaussian function using a set of fit parameters, which exhibit a regular pattern as a function of beam energy. By extrapolating the parameters to a higher energy of \sNN~=~5.02 TeV, we have obtained the charged particle multiplicity densities, \Eta-distributions and energy densities for various centralities. Incidentally, these results match well with some of the recently published data by the ALICE collaboration.

   nucl-exhep-exhep-phPRC(2016)·16 citations
2. 02*

   An improved method for estimating the neutron background in measurements of neutron capture reactions

   P. Žugec🇭🇷 · D. Bosnar🇭🇷 · N. Colonna🇮🇹 · F. Gunsing🇫🇷

   The relation between the neutron background in neutron capture measurements and the neutron sensitivity related to the experimental setup is examined. It is pointed out that a proper estimate of the neutron background may only be obtained by means of dedicated simulations taking into account the full framework of the neutron-induced reactions and their complete temporal evolution. No other presently available method seems to provide reliable results, in particular under the capture resonances. An improved neutron background estimation technique is proposed, the main improvement regarding the treatment of the neutron sensitivity, taking into account the temporal evolution of the neutron-induced reactions. The technique is complemented by an advanced data analysis procedure based on relativistic kinematics of neutron scattering. The analysis procedure allows for the calculation of the neutron background in capture measurements, without requiring the time-consuming simulations to be adapted to each particular sample. A suggestion is made on how to improve the neutron background estimates if neutron background simulations are not available.

   nucl-exphysics.comp-phphysics.ins-detNucl.Instrum.Meth.A(2016)·5 citations
3. 03*

   Accessing proton generalized parton distributions and pion distribution amplitudes with the exclusive pion-induced Drell-Yan process at J-PARC

   Takahiro Sawada🇹🇼 · Wen-Chen Chang🇹🇼 · Shunzo Kumano🇯🇵 · Jen-Chieh Peng🇺🇸 · Shinya Sawada🇯🇵 · Kazuhiro Tanaka🇯🇵

   Generalized parton distributions (GPDs) encoding multidimensional information of hadron partonic structure appear as the building blocks in a factorized description of hard exclusive reactions. The nucleon GPDs have been accessed by deeply virtual Compton scattering and deeply virtual meson production with lepton beam. A complementary probe with hadron beam is the exclusive pion-induced Drell-Yan process. In this paper, we discuss recent theoretical advances on describing this process in terms of nucleon GPDs and pion distribution amplitudes. Furthermore, we address the feasibility of measuring the exclusive pion-induced Drell-Yan process ${\pi }^{-}p\to {\mu }^{+}{\mu }^{-}n$ via a spectrometer at the High Momentum Beamline being constructed at J-PARC in Japan. Realization of such measurement at J-PARC will provide a new test of perturbative QCD descriptions of a novel class of hard exclusive reactions. It will also offer the possibility of experimentally accessing nucleon GPDs at large timelike virtuality.

   nucl-exhep-exhep-phnucl-thPRD(2016)·63 citations
4. 04*

   Performance of the ALICE secondary vertex b-tagging algorithm

   Gyulnara Eyyubova🇷🇺 · Lukáš Kramárik (for the ALICE Collaboration)🇨🇿

   The identification of jets originating from beauty quarks in heavy-ion collisions is important to study the properties of the hot and dense matter produced in such collisions. A variety of algorithms for b-jet tagging was elaborated at the LHC experiments. They rely on the properties of B hadrons, i.e. their long lifetime, large mass and large multiplicity of decay products. In this work, the b-tagging algorithm based on displaced secondary-vertex topologies is described. We present Monte Carlo based performance studies of the algorithm for charged jets reconstructed with the ALICE tracking system in p-Pb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV. The tagging efficiency, rejection rate and the correction of the smearing effects of non-ideal detector response are presented.

   ↳ physics.ins-dethep-exnucl-exEPJ Web Conf.(2016)·2 citations
5. 05*

   Electric dipole moment of the deuteron in the standard model with $NN-\Lambda N-\Sigma N$ coupling

   Nodoka Yamanaka

   We calculate the electric dipole moment (EDM) of the deuteron in the standard model with $|\Delta S|=1$ interactions by taking into account the $NN-\Lambda N-\Sigma N$ channel coupling, which is an important nuclear level systematics. The two-body problem is solved with the Gaussian Expansion Method using the realistic Argonne $v18$ nuclear force and the $YN$ potential which can reproduce the binding energies of ${}_{\Lambda }^3$H, ${}_{\Lambda }^3$He, and ${}_{\Lambda }^4$He. The $|\Delta S|=1$ interbaryon potential is modeled by the one-meson exchange process. It is found that the deuteron EDM is modified by less than 10\%, and the main contribution to this deviation is due to the polarization of the hyperon-nucleon channels. The effect of the $YN$ interaction is small, and treating $\Lambda N$ and $\Sigma N$ channels as free is a good approximation for the EDM of the deuteron.

   ↳ nucl-thhep-exhep-phnucl-exNPA(2017)·27 citations
6. 06*

   Jet quenching parameter of quark-gluon plasma in strong magnetic field: Perturbative QCD and AdS/CFT correspondence

   Shiyong Li🇺🇸 · Kiminad A. Mamo🇺🇸 · Ho-Ung Yee🇺🇸

   We compute the jet quenching parameter $\hat{q}$ of QCD plasma in the presence of strong magnetic field in both weakly and strongly coupled regimes. In weakly coupled regime, we compute $\hat{q}$ in perturbative QCD at complete leading order (that is, leading log as well as the constant under the log) in QCD coupling constant ${\alpha }_s$, assuming the hierarchy of scales ${\alpha }_{s}eB\ll T^2\ll eB$. We consider two cases of jet orientations with respect to the magnetic field: 1) the case of jet moving parallel to the magnetic field, 2) the case jet moving perpendicular to the magnetic field. In the former case, we find $\hat{q}\sim {\alpha }_s^2(eB)T\log (1/{\alpha }_s)$, while in the latter we have $\hat{q}\sim {\alpha }_s^2(eB)T\log (T^2/{\alpha }_{s}eB)$. In both cases, this leading order result arises from the scatterings with thermally populated lowest Landau level quarks. In strongly coupled regime described by AdS/CFT correspondence, we find $\hat{q}\sim \sqrt{\lambda }(eB)T$ or $\hat{q}\sim \sqrt{\lambda }\sqrt{eB}{T}^2$ in the same hierarchy of $T^2\ll eB$ depending on whether the jet is moving parallel or perpendicular to the magnetic field, respectively, which indicates a universal dependence of $\hat{q}$ on $(eB)T$ in both regimes for the parallel case, the origin of which should be the transverse density of lowest Landau level states proportional to $eB$. Finally, the asymmetric transverse momentum diffusion in the case of jet moving perpendicular to the magnetic field may give an interesting azimuthal asymmetry of the gluon Bremsstrahlung spectrum in the BDMPS-Z formalism.

   ↳ hep-phhep-thnucl-exnucl-thPRD(2016)·51 citations
7. 07*

   A ferro-deformation at the open quantum system with protons, Z = 8, neutrons, N = 20: 28O

   Chang-Bum Moon

   We offer a possibility that the nuclear system with protons, Z = 8 has a large deformation at neutrons, N = 20; 28O that is beyond the neutron drip line. According to our previous works [arXiv: 1604.05013, 1604.02786, 1604.01017], it is expected that the ferro-deformation would occur at Z = 8, N = 20 through a shape phase transition at N = 18 out of N =16. The shape transition can be explained in terms of isospin dependent spin-orbital interactions between neutrons in the d3/2 orbital and protons in the d5/2 orbital, by yielding both the neutron and the proton pseudo-shell configurations built on each combined subshells. We argue that such a large deformation at N = 18 would be responsible for the 26O to be unbound, leading to a ground state neutron emitter. The ferro-deformation is mapped on the nuclear chart such that is around the following critical proton, neutron coordinates, (Z, N); (64, 104), (40, 64), (20, 40), (8, 20). This configuration depicts a beautiful pattern coming from a harmonious order in the microscopic quantum world.

   ↳ nucl-thnucl-ex2 citations
8. 08*

   Strangeness in nuclear physics

   A. Gal🇮🇱 · E.V. Hungerford🇺🇸 · D.J. Millener🇺🇸

   Extensions of nuclear physics to the strange sector are reviewed, covering data and models of Lambda and other hypernuclei, multi-strange matter, and anti-kaon bound states and condensation. Past achievements are highlighted, present unresolved problems discussed, and future directions outlined.

   ↳ nucl-thnucl-exRMP(2016)·545 citations
9. 09*

   A new scheme for short baseline electron antineutrino disappearance study

   Jae Won Shin🇰🇷 · Myung-Ki Cheoun🇰🇷 · Toshitaka Kajino🇯🇵 · Takehito Hayakawa🇯🇵

   A new scheme for the short baseline electron antineutrino (${\bar{\nu }}_e$) disappearance study is investigated. We propose to use an intense neutron emitter, ${}^{252}$Cf, which produces ${}^8$Li isotope through the ${}^7$Li(n,$\gamma$)${}^8$Li reaction; ${}^8$Li is a ${\bar{\nu }}_e$ emitter via ${\beta }^{-}$ decay. Because this ${\bar{\nu }}_e$ source needs neither accelerator nor reactor facilities, the ${\bar{\nu }}_e$ can be placed on any neutrino detectors as closely as possible. This short baseline circumstance with a suitable detector enables us to study the existence of possible sterile neutrinos, in particular, on 1 eV mass scale. Also, complementary comparison studies among different neutrino detectors can become feasible by using ${\bar{\nu }}_e$ from the ${}^8$Li source. As an example, applications to hemisphere and cylinder shape scintillator detectors are performed in detail with the expectation signal modification by the sterile neutrino. Sensitivities to mass and mixing angles of sterile neutrinos are also presented for comparison with those of other neutrino experiments.

   ↳ physics.ins-detnucl-exJ.Phys.G(2017)·2 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.