Nuclear Theory·nucl-th

Tuesday·July 19, 2016

15 papers—6 primary·9 cross-listed

01
[Submitted on 16 Jul 2016]
Test the chiral magnetic effect with isobaric collisions
Wei-Tian Deng🇨🇳 · Xu-Guang Huang🇺🇸 · Guo-Liang Ma🇨🇳 · Gang Wang🇺🇸
The quark-gluon matter produced in relativistic heavy-ion collisions may contain local domains in which P and CP symmetries are not preserved. When coupled with an external magnetic field, such P- and CP-odd domains will generate electric currents along the magnetic field --- a phenomenon called the chiral magnetic effect (CME). Recently, the STAR Collaboration at RHIC and the ALICE Collaboration at the LHC released data of charge-dependent azimuthal-angle correlators with features consistent with the CME expectation. However, the experimental observable is contaminated with significant background contributions from elliptic-flow-driven effects, which makes the interpretation of the data ambiguous. In this Letter, we show that the collisions of isobaric nuclei, $_{44}^{96}$ Ru + $_{44}^{96}$ Ru and $_{40}^{96}$ Zr + $_{40}^{96}$ Zr, provide an ideal tool to disentangle the CME signal from the background effects. Our simulation demonstrates that the two collision types at $s_{NN} = 200$ GeV have more than $10%$ difference in the CME signal and less than $2%$ difference in the elliptic-flow-driven backgrounds for the centrality range of $20 - 60%$ .
Comments:
V1: 4 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1607.04697 [pdf]
PRC(2016)·121 citations
02
[Submitted on 16 Jul 2016]
Bulk viscosity for pion and nucleon thermal fluctuation in the hadron resonance gas model
Sabyasachi Ghosh🇮🇳 · Sandeep Chatterjee🇮🇳 · Bedangdas Mohanty🇮🇳
We have calculated microscopically bulk viscosity of hadronic matter, where equilibrium thermodynamics for all hadrons in medium are described by Hadron Resonance Gas (HRG) model. Considering pions and nucleons as abundant medium constituents, we have calculated their thermal widths, which inversely control the strength of bulk viscosities for respective components and represent their in-medium scattering probabilities with other mesonic and baryonic resonances, present in the medium. Our calculations show that bulk viscosity increases with both temperature and baryon chemical potential, whereas viscosity to entropy density ratio decreases with temperature and with baryon chemical potential, the ratio increases first and then decreases. The decreasing nature of the ratio with temperature is observed in most of the earlier investigations with few exceptions. We find that the temperature dependence of bulk viscosity crucially depends on the structure of the relaxation time. Along the chemical freeze-out line in nucleus-nucleus collisions with increasing collision energy, bulk viscosity as well as the bulk viscosity to entropy density ratio decreases, which also agrees with earlier references. Our results indicate the picture of a strongly coupled hadronic medium.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1607.04779 [pdf]
PRC(2016)·12 citations
03
[Submitted on 16 Jul 2016]
Investigation of the Ground and Excited States of the 3H and 4He Nuclei by Using the Methods of Group Theory
S. B. Doma · H. S. El-Gendy
The method of group theory is applied to investigate the ground and the excited states of the triton and helium nuclei by using the translation invariant shell model with basis functions corresponding to even number of quanta of excitations in the range 0 less than or equal to N less than or equal to 20. Accordingly, the ground and first excited state wave functions and energies, the S, P and D state probabilities, the root mean square radius and the magnetic dipole moment of triton have been investigated. Also, the energies and wave functions of the ground and the even parity excited states and the root mean square radius of helium have been investigated. Two residual two body interactions together with two three nucleon interactions have been used in the calculations. Moreover, the convergence of calculations has been examined by extrapolating the results with N less than or equals to 20 step by step to reach N equals to 30 for the two nuclei.
Comments:
22. arXiv admin note: substantial text overlap with arXiv:1509.01730
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.04810 [pdf]
0 citations
04
[Submitted on 17 Jul 2016]
Quest for magicity in hypernuclei
M. Ikram · Bharat Kumar · S. K. Biswal · S. K. Patra
In present study, we search the lambda magic number in hypernuclei within the framework of relativistic mean field theory (RMF) with inclusion of hyperon-nucleon and hyperon-hyperon potentials. Based on one- and two-lambda separation energy and two-lambda shell gap, 2, 8, 14, 18, 20, 28, 34, 40, 50, 58, 68, 70 and 82 are suggested to be the $Λ$ magic number within the present approach. The weakening strength of $Λ$ spin-orbit interaction is responsible for emerging the new lambda shell closure other than the model scheme. The predicted $Λ$ magic numbers are in remarkable agreement with earlier predictions and hypernuclear magicity quite resembles with nuclear magicity. %Our results also support the nuclear magicity, Our results are supported by nuclear magicity, where neutron number N = 34 is experimentally observed as a magic which is one of the $Λ$ closed shell in our predictions. In addition, the stability of hypernuclei is also examined by calculating the binding energy per particle, where Ni hypernucleus is found to be most tightly bound triply magic system in considered hypernuclei. Nucleon and lambda density distributions are observed and it is found that introduced $Λ$ 's have significant impact on total density and reduces the central depression of the core nucleus. Nucleon and lambda mean field potentials and spin-orbit interaction potentials are also observed for predicted triply magic hypernuclei and the addition of $Λ$ 's affect the both the potentials to a large extent. The single-particle energy levels are also analyzed to explain the shell gaps for triply magic multi- $Λ$ hypernuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.04865 [pdf]
IJMPE(2016)·1 citation
05
[Submitted on 18 Jul 2016]
Applicability of the continuum-discretized coupled-channels method to the deuteron breakup at low energies
Kazuyuki Ogata · Kazuki Yoshida
We re-examine the deuteron elastic breakup cross sections on 12C and 10Be at low incident energies, for which a serious discrepancy between the continuum-discretized coupled-channels method (CDCC) and the Faddeev-Alt-Grassberger-Sandhas theory (FAGS) was pointed out. We show the closed-channels neglected in the preceding study affect significantly the breakup cross section calculated with CDCC, resulting in good agreement with the result of FAGS.
Comments:
4 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1607.04969 [pdf]
PRC(2016)·25 citations
06
[Submitted on 18 Jul 2016]
Double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions
Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱
We present first measurable predictions for electromagnetic (two-photon) double scattering production of two positron-electron pairs in ultraperipheral heavy-ion collisions at LHC. Measureable cross sections are obtained with realistic cuts on electron/positron (pseudo)rapidities and transverse momenta for the ALICE and ATLAS or CMS experiments. The predictions for total and differential cross sections are presented. We show also two-dimensional distributions in rapidities of the opposite-sign (from the same or different subcollisions) and of the same-sign ( $e^{+} e^{+}$ or $e^{-} e^{-}$ ) electrons and in rapidity distance between them. Expected number of events are presented and discussed. Our calculations strongly suggest that relevant measurements with the help of ATLAS, CMS and ALICE detectors are possible in a near future.
Comments:
10 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1607.05095 [pdf]
PLB(2016)·19 citations
07
[Submitted on 15 Jul 2016] (cross-list from hep-ph)
Matter Neutrino Resonance Transitions above a Neutron Star Merger Remnant
Yong-Lin Zhu🇺🇸 · Albino Perego🇩🇪 · Gail C. McLaughlin🇺🇸
The Matter-Neutrino Resonance (MNR) phenomenon has the potential to significantly alter the flavor content of neutrinos emitted from compact object mergers. We present the first calculations of MNR transitions using neutrino self interaction potentials and matter potentials generated selfconsistently from a dynamical model of a three-dimensional neutron star merger. In the context of the single angle approximation, we find that Symmetric and Standard MNR transitions occur in both normal and inverted hierarchy scenarios. We examine the spatial regions above the merger remnant where propagating neutrinos will encounter the matter neutrino resonance and find that a significant fraction of the neutrinos are likely to undergo MNR transitions.
Comments:
13 pages, 11 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1607.04671 [pdf]
PRD(2016)·86 citations
08
[Submitted on 16 Jul 2016] (cross-list from hep-ph)
Spectrum and electromagnetic transitions of bottomonium
Wei-Jun Deng🇨🇳 · Hui Liu🇨🇳 · Long-Cheng Gui🇨🇳 · Xian-Hui Zhong🇨🇳
Stimulated by the exciting progress in the observation of new bottomonium states, we study the bottomonium spectrum. To calculate the mass spectrum, we adopt a nonrelativistic screened potential model. The radial Schrödinger equation is solved with the three-point difference central method, where the spin-dependent potentials are dealt with non-perturbatively. With this treatment, the corrections of the spin-dependent potentials to the wave functions can be included successfully. Furthermore, we calculate the electromagnetic transitions of the $n S$ ( $n \leq 4$ ), $n P$ ( $n \leq 3$ ), and $n D$ ( $n \leq 2$ ) bottomonium states with a nonrelativistic electromagnetic transition operator widely applied to meson photoproduction reactions. Our predicted masses, hyperfine and fine splittings, electromagnetic transition widths and branching ratios of the bottomonium states are in good agreement with the available experimental data. Especially, the EM transitions of $Υ (3 S) \to χ_{b 1, 2} (1 P) γ$ , which were not well understood in previous studies, can be reasonably explained by considering the corrections of the spin-dependent interactions to the wave functions. We also discuss the observations of the missing bottomonium states by using radiative transitions. Some important radiative decay chains involving the missing bottomonium states are suggested to be observed. We hope our study can provide some useful references to observe and measure the properties of bottomonium mesons in forthcoming experiments.
Comments:
14 pages, 1 figure, revised version. To appear in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1607.04696 [pdf]
PRD(2017)·89 citations
09
[Submitted on 16 Jul 2016] (cross-list from astro-ph.HE)
Properties of strongly magnetized ultradense matter and their imprints on magnetar pulsations
C. Vásquez Flores🇧🇷 · L. B. Castro🇧🇷 · G. Lugones🇧🇷
We investigate the effect of strong magnetic fields on the adiabatic radial oscillations of hadronic stars. We describe magnetized hadronic matter within the framework of the relativistic nonlinear Walecka model and integrate the equations of relativistic radial oscillations to determine the fundamental pulsation mode. We consider that the magnetic field increases, in a density dependent way, from the surface, where it has a typical magnetar value of $1 0^{15}$ G, to the interior of the star where it can be as large as $3 \times 1 0^{18}$ G. We show that magnetic fields of the order of $1 0^{18}$ G at the stellar core produce a significant change in the frequency of neutron star pulsations with respect to unmagnetized objects. If radial pulsations are excited in magnetar flares, they can leave an imprint in the flare lightcurves and open a new window for the study of highly magnetized ultradense matter.
Comments:
To be published in Physical Review C
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04707 [pdf]
PRC(2016)·7 citations
10
[Submitted on 16 Jul 2016] (cross-list from hep-ph)
Forward Hadron Productions in Proton-Proton Collisions in Small- $x$ Formalism
Kazuhiro Watanabe🇨🇳 · Bo-Wen Xiao🇨🇳
Employing the so-called hybrid formalism, we calculate the cross section of inclusive hadron production in proton-proton collisions at forward rapidity in small- $x$ formalism at one-loop order. For the case of hadron production at forward rapidity, we can uses collinear parton distributions for projectile proton and $k_{⊥}$ dependent gluon distribution for target proton. We show that collinear divergences associated with initial and final state parton radiations are renormalized into parton distributions and fragmentation functions in terms of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution equation, respectively. Furthermore, rapidity divergence can be absorbed into the wave function of target proton which gives rise to the well-known Balitsky-Fadin-Kuraev-Lipatov equation. These divergences are completely separated from the short distance partonic hard parts, which is now finite at the next-to-leading order accuracy. The result presented in this paper can be reckoned as a baseline calculation without any non-linear QCD effects in small- $x$ formalism. As a consistency check, we compare our results with the previous calculation for non-linear proton-nucleus collisions in the small- $x$ formalism and find complete agreement in the dilute and large $N_{c}$ limit. In phenomenology, the direct comparison of the above two separate calculations can reveal the role and strength of the non-linear dynamics in high energy QCD, and thus help us reliably study the onset of gluon saturation when genuine non-linear interactions become important.
Comments:
24 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04726 [pdf]
PRD(2016)·4 citations
11
[Submitted on 17 Jul 2016] (cross-list from hep-th)
Phases of kinky holographic nuclear matter
Matthew Elliot-Ripley🇬🇧 · Paul Sutcliffe🇬🇧 · Marija Zamaklar🇬🇧
Holographic QCD at finite baryon number density and zero temperature is studied within the five-dimensional Sakai-Sugimoto model. We introduce a new approximation that models a smeared crystal of solitonic baryons by assuming spatial homogeneity to obtain an effective kink theory in the holographic direction. The kink theory correctly reproduces a first order phase transition to lightly bound nuclear matter. As the density is further increased the kink splits into a pair of half-kink constituents, providing a concrete realization of the previously suggested dyonic salt phase, where the bulk soliton splits into constituents at high density. The kink model also captures the phenomenon of baryonic popcorn, in which a first order phase transition generates an additional soliton layer in the holographic direction. We find that this popcorn transition takes place at a density below the dyonic salt phase, making the latter energetically unfavourable. However, the kink model predicts only one pop, rather than the sequence of pops suggested by previous approximations. In the kink model the two layers produced by the single pop form the surface of a soliton bag that increases in size as the baryon chemical potential is increased. The interior of the bag is filled with abelian electric potential and the instanton charge density is localized on the surface of the bag. The soliton bag may provide a holographic description of a quarkyonic phase.
Comments:
18 pages, 5 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04832 [pdf]
JHEP(2016)·35 citations
12
[Submitted on 17 Jul 2016] (cross-list from hep-ph)
Single-inclusive jet production in electron-nucleon collisions through next-to-next-to-leading order in perturbative QCD
Gabriel Abelof🇺🇸 · Radja Boughezal🇺🇸 · Xiaohui Liu🇺🇸 · Frank Petriello🇺🇸
We compute the $O (α^{2} α_{s}^{2})$ perturbative corrections to inclusive jet production in electron-nucleon collisions. This process is of particular interest to the physics program of a future Electron Ion Collider (EIC). We include all relevant partonic processes, including deep-inelastic scattering contributions, photon-initiated corrections, and parton-parton scattering terms that first appear at this order. Upon integration over the final-state hadronic phase space we validate our results for the deep-inelastic corrections against the known next-to-next-to-leading order (NNLO) structure functions. Our calculation uses the $N$ -jettiness subtraction scheme for performing higher-order computations, and allows for a completely differential description of the deep-inelastic scattering process. We describe the application of this method to inclusive jet production in detail, and present phenomenological results for the proposed EIC. The NNLO corrections have a non-trivial dependence on the jet kinematics and arise from an intricate interplay between all contributing partonic channels.
Comments:
9 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.04921 [pdf]
PLB(2016)·50 citations
13
[Submitted on 18 Jul 2016] (cross-list from hep-lat)
Lattice Prediction for Deeply Bound Doubly Heavy Tetraquarks
Anthony Francis🇨🇦 · Renwick J. Hudspith🇨🇦 · Randy Lewis🇨🇦 · Kim Maltman🇦🇺
We investigate the possibility of $q q^{'} b ˉ b ˉ$ tetraquark bound states using $n_{f} = 2 + 1$ lattice QCD ensembles with pion masses $≃ 164$ , $299$ , and $415$ MeV. Motivated by observations from heavy baryon phenomenology, we consider two lattice interpolating operators both of which are expected to couple efficiently to tetraquark states: one with diquark-antidiquark and one with a meson-meson structure. Using nonrelativistic QCD to simulate the bottom quarks, we study the $u d b ˉ b ˉ$ , $ℓ s b ˉ b ˉ$ channels with $ℓ = u, d$ , and find unambiguous signals for strong-interaction-stable $J^{P} = 1^{+}$ tetraquarks. These states are found to lie $189 (10)$ and $98 (7)$ MeV below the corresponding free two-meson thresholds.
Comments:
5 pages, 3 figures; published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1607.05214 [pdf]
PRL(2017)·244 citations
14
[Submitted on 18 Jul 2016] (cross-list from hep-ph)
Nonlinear dynamics from the relativistic Boltzmann equation in the Friedmann-Lemaître-Robertson-Walker spacetime
D. Bazow🇺🇸 · G. S. Denicol🇧🇷 · U. Heinz🇺🇸 · M. Martinez🇺🇸 · J. Noronha🇧🇷
The dissipative dynamics of an expanding massless gas with constant cross section in a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) universe is studied. The mathematical problem of solving the full nonlinear relativistic Boltzmann equation is recast into an infinite set of nonlinear ordinary differential equations for the moments of the one-particle distribution function. Momentum-space resolution is determined by the number of non-hydrodynamic modes included in the moment hierarchy, i.e., by the truncation order. We show that in the FLRW spacetime the non-hydrodynamic modes decouple completely from the hydrodynamic degrees of freedom. This results in the system flowing as an ideal fluid while at the same time producing entropy. The solutions to the nonlinear Boltzmann equation exhibit transient tails of the distribution function with nontrivial momentum dependence. The evolution of this tail is not correctly captured by the relaxation time approximation nor by the linearized Boltzmann equation. However, the latter probes additional high-momentum details unresolved by the relaxation time approximation. While the expansion of the FLRW spacetime is slow enough for the system to move towards (and not away from) local thermal equilibrium, it is not sufficiently slow for the system to actually ever reach complete local equilibrium. Equilibration is fastest in the relaxation time approximation, followed, in turn, by kinetic evolution with a linearized and a fully nonlinear Boltzmann collision term.
Comments:
23 pages, 8 figures. Updated references, corrected typos. Minor changes in the text. Published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Statistical Mechanics (cond-mat.stat-mech); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1607.05245 [pdf]
PRD(2016)·57 citations
15
[Submitted on 14 Jul 2016] (cross-list from cond-mat.mtrl-sci)
Ag diffusion in SiC high-energy grain boundaries: kinetic Monte Carlo study with first-principle calculations
Hyunseok Ko · Jie Deng · Izabela Szlufarska · Dane Morgan
The diffusion of silver (Ag) impurities in high energy grain boundaries (HEGBs) of cubic (3C) silicon carbide (SiC) is studied using an ab initio based kinetic Monte Carlo (kMC) model. This study assesses the hypothesis that the HEGB diffusion is responsible for Ag release in Tristructural-Isotropic fuel particles, and provides a specific example to increase understanding of impurity diffusion in highly disordered grain boundaries. The HEGB environment was modeled by an amorphous SiC. The structure and stability of Ag defects were calculated using density functional theory code. The defect energetics suggested that the fastest diffusion takes place via an interstitial mechanism in a-SiC. The formation energy of Ag interstitials and the kinetic resolved activation energies between them were well approximated with Gaussian distributions that were then sampled in the kMC. The diffusion of Ag was simulated with the effective medium model using kMC. At 1200-1600C, Ag in a HEGB is predicted to exhibit an Arrhenius type diffusion and with a diffusion prefactor and effective activation energy of (2.73+-1.09)*10-10 m2s-1 and 2.79+-0.18 eV, respectively. The comparison between HEGB results to other theoretical studies suggested not only that GB diffusion is predominant over bulk diffusion, but also that the HEGB is one of fastest grain boundary paths for Ag diffusion in SiC. The Ag diffusion coefficient in the HEGB shows a good agreement with ion-implantation measurements, but is 2-3 orders of magnitude lower than the diffusion coefficients extracted from integral release measurements. The discrepancy between GB diffusion and integral release measurements suggests that other contributions are responsible for the fast release of Ag in some experiments and we propose that these contributions may arise from radiation enhanced diffusion.
Subjects:
cond-mat.mtrl-sci (cond-mat.mtrl-sci); Nuclear Theory (nucl-th)
arXiv:
1607.05253 [pdf]
Comput.Mater.Sci.(2016)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE