Nuclear Theory·nucl-th

Monday·July 23, 2018

11 papers—6 primary·5 cross-listed

01
[Submitted on 19 Jul 2018]
Upsilon states in magnetized nuclear matter
Amal Jahan C.S.🇮🇳 · Shivam Kesarwani🇮🇳 · Sushruth Reddy P.🇮🇳 · Nikhil Dhale🇮🇳 · Amruta Mishra🇮🇳
The mass modifications of the bottomonium states ( $Υ (N S)$ , $N = 1, 2, 3, 4$ and $Υ (1 D)$ ) in magnetized nuclear matter are studied using chiral effective model. The in-medium masses are calculated from the medium modification of the scalar dilaton field in the chiral effective model, which simulates the gluon condensates of QCD. The strengths of the wave functions (assumed to be harmonic oscillator wave functions) denoted by the parameter, $β$ , of the $Υ (N S)$ , $N = 1, 2, 3, 4$ , are fitted from their observed decay widths to $e^{+} e^{-}$ . The decay width for the channel, $Υ (1 D) \to e^{+} e^{-}$ %, which has not yet been observed experimentally, has been predicted in the present work, by using the value of the parameter, $β$ for $Υ (1 D)$ , interpolated from the $β$ versus mass relation, for the upsilon states. The effects of the isospin asymmetry of the nuclear medium on the masses of the upsilon states are investigated and are observed to be large for high densities. This should have observable consequences at the asymmetric heavy ion collisions at the Compressed baryonic matter (CBM) experiments at FAIR, GSI as well as at SPS, CERN. The study of the bottomonium states at CBM will however require access to higher energies than the energy regime planned at present. The effects of magnetic field on the masses of bottomonium states in nuclear matter are studied in the present work. These masses are investigated including the anomalous magnetic moments (AMM) of the nucleons, and compared to the results when the AMMs of nucleons are not taken into account. The effects of magnetic field as well as isospin asymmetry on the upsilon masses are obserevd to be large at high densities.
Comments:
19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1803.04322, arXiv:1801.06405
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1807.07572 [pdf]
16 citations
02
[Submitted on 20 Jul 2018]
Extracting Nuclear Symmetry Energies at High Densities from Observations of Neutron Stars and Gravitational Waves
Nai-Bo Zhang🇨🇳 · Bao-An Li🇺🇸
By numerically inverting the Tolman-Oppenheimer-Volkov (TOV) equation using an explicitly isospin-dependent parametric Equation of State (EOS) of dense neutron-rich nucleonic matter, a restricted EOS parameter space is established using observational constraints on the radius, maximum mass, tidal polarizability and causality condition of neutron stars (NSs). The constraining band obtained for the pressure as a function of energy (baryon) density is in good agreement with that extracted recently by the LIGO+Virgo Collaborations from their improved analyses of the NS tidal polarizability in GW170817. Rather robust upper and lower boundaries on nuclear symmetry energies are extracted from the observational constraints up to about twice the saturation density $ρ_{0}$ of nuclear matter. More quantitatively, the symmetry energy at $2 ρ_{0}$ is constrained to $E_{sym} (2 ρ_{0}) = 46.9 \pm 10.1$ MeV excluding many existing theoretical predictions scattered between $E_{sym} (2 ρ_{0}) = 15$ and 100 MeV. Moreover, by studying variations of the causality surface where the speed of sound equals that of light at central densities of the most massive neutron stars within the restricted EOS parameter space, the absolutely maximum mass of neutron stars is found to be 2.40 M $_{⊙}$ approximately independent of the EOSs used. This limiting mass is consistent with findings of several recent analyses and numerical general relativity simulations about the maximum mass of the possible super-massive remanent produced in the immediate aftermath of GW170817.
Comments:
Version accepted. No change in conclusions. Added 6 new figures and associated discussions to address issues on (1) Why/how to go beyond the popular polytrope EOSs, (2) how to numerically solve the NS inverse-structure problem, (3) how an absolutely maximum mass of 2.4 M_sun independent of the EOS is obtained in comparison with earlier predictions and reports after GW170817
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Experiment (nucl-ex)
arXiv:
1807.07698 [pdf]
EPJA(2019)·126 citations
03
[Submitted on 20 Jul 2018]
Analytical forms of the deuteron wave function for Nijmegen group potentials and polarization characteristics of A(d,d')X reactions
V.I. Zhaba
Polarization observables of the A(d,d')X reactions have been calculated according to the received coeffcients of the analytical form for deuteron wave function in coordinate space for the nucleon-nucleon Nijmegen group potentials (NijmI, NijmII, Nijm93). The obtained values of tensor Ayy and vector Ay analyzing powers have been compared with the published experimental data at t- scaling for the inelastic scattering of deuterons on hydrogen, carbon and beryllium. Theoretical values of tensor-tensor Kyy and vector-vector Ky polarization transfers have been also evaluated in the plane-wave impulse approximation.
Comments:
14 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.07806 [pdf]
Mod.Phys.Lett.A(2018)·5 citations
04
[Submitted on 20 Jul 2018]
Geometric scaling in symmetric nucleus-nucleus collisions
Rudolph Rogly🇫🇷 · Giuliano Giacalone🇫🇷 · Jean-Yves Ollitrault🇫🇷
We show that the centrality dependence of the multiplicity is identical in Pb+Pb and Xe+Xe collisions at the LHC, up to a constant factor. This geometric scaling is revealed if one defines centrality according to impact parameter, as opposed to the usual experimental definition, which is in terms of multiplicity. We reconstruct the impact parameter dependence of the multiplicity from experimental data using a recently-developed inversion method, which turns out to describe ALICE Xe+Xe multiplicity data much better than usual Monte Carlo Glauber fits. The multiplicity as function of impact parameter extracted from ALICE data is compared to model calculations.
Comments:
4 pages, proceedings of Quark Matter 2018. v2: minor revision. Figure 3 corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.07831 [pdf]
NPA(2019)·4 citations
05
[Submitted on 20 Jul 2018]
Low-energy corrections to the eikonal description of elastic scattering and breakup of one-neutron halo nuclei in nuclear-dominated reactions
Chloë Hebborn🇧🇪 · Pierre Capel🇩🇪
Background: The eikonal approximation is a high-energy reaction model which is very computationally efficient and provides a simple interpretation of the collision. Unfortunately, it is not valid at energies around 10 MeV/nucleon, the range of energy of HIE-ISOLDE at CERN and the future ReA12 at MSU. Fukui etal. [Phys. Rev. C 90, 034617 (2014)] have shown that a simple semiclassical correction of the projectile-target deflection could improve the description of breakup of halo nuclei on heavy targets down to 20 MeV/nucleon. Purpose: We study two similar corrections, which aim at improving the projectile-target relative motion within the eikonal approximation, with the goal to extend its range of validity down to 10 MeV/nucleon in nuclear-dominated collisions, viz. on light targets. The semiclassical correction substitutes the impact parameter by the distance of closest approach of the corresponding classical trajectory. The exact continued $S$ -matrix correction replaces the eikonal phase by the exact phase shift. Both corrections successfully describe the elastic scattering of one-neutron halo nuclei. Method: We extend these corrections and study their efficiency in describing the breakup channel. We evaluate them in the case of $^{11} Be$ impinging on $^{12} C$ at 20 and 10 MeV/nucleon. Results: Albeit efficient to reproduce the elastic channel, these corrections do not improve the description of the breakup of halo nuclei within the eikonal approximation down to 20 MeV/nucleon. Conclusions: Our analysis of these corrections shows that improving the projectile-target relative motion is not the ultimate answer to extend the eikonal approximation down to low energies. We suggest another avenue to reach this goal.
Comments:
7 pages, 4 figures, accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.07877 [pdf]
PRC(2018)·13 citations
06
[Submitted on 20 Jul 2018]
Coexistence of chiral symmetry and pseudospin symmetry in one nucleus: triplet bands in $^{105}$ Ag
H. Jia🇨🇳 · B. Qi🇨🇳 · C. Liu🇨🇳 · S. Y. Wang🇨🇳
The nearly degenerate triplet bands with the $π g_{9/2}^{- 1} \otimes ν h_{11/2} (g_{7/2}, d_{5/2})$ configuration in $^{105}$ Ag are studied via the relativistic mean-field (RMF) theory and the multiparticle plus rotor model (MPRM), which indicates that these bands are associated with chiral symmetry and pseudospin symmetry. The configuration-fixed constrained triaxial RMF calculations exhibit the pseudospin symmetry in single particle spectra and the triaxial shape coexistence. The experimental excitation energies and the electromagnetic transition probabilities for the triplet bands are reproduced very well by the MPRM calculaitons. The chiral doublet bands show the same phase in the $B (M 1) / B (E 2)$ staggering, while the pseudospin doublet bands hold the opposite phase. The coexistence of chiral symmetry and pseudospin symmetry in one nucleus and its corresponding characteristic of the rotational structure are discussed for the first time.
Comments:
15pages,4figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1807.07922 [pdf]
J.Phys.G(2019)·14 citations
07
[Submitted on 19 Jul 2018] (cross-list from hep-ph)
Transverse momentum dependent distributions with jets
Daniel Gutierrez-Reyes🇪🇸 · Ignazio Scimemi🇪🇸 · Wouter J. Waalewijn🇳🇱 · Lorenzo Zoppi🇳🇱
We investigate the use of jets to measure transverse momentum dependent distributions (TMDs). The example we use to present our framework is the dijet momentum decorrelation at lepton colliders. Translating this momentum decorrelation into an angle $θ ≪ 1$ , we analyze the factorization of the cross section for the cases $θ ≫ R$ , $θ \sim R$ and $θ ≪ R$ , where $R$ is the jet radius. Critically, for the Winner-Take-All axis, the jet TMD has the same double-scale renormalization group evolution as TMD fragmentation functions for all radii $R$ . TMD fragmentation functions in factorization theorems may then simply be replaced by the jet TMDs we calculate, and all ingredients to perform the resummation to next-to-next-to-leading logarithmic accuracy are available. Our approach also applies to semi-inclusive deep inelastic scattering (SIDIS), where a jet instead of a hadron is measured in the final state, and we find a clean method to probe the intrinsic transverse momentum of quarks and gluons in the proton that is less sensitive to final-state nonperturbative effects.
Comments:
6 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.07573 [pdf]
PRL(2018)·81 citations
08
[Submitted on 19 Jul 2018] (cross-list from hep-th)
Hydrodynamic modes in a magnetized chiral plasma with vorticity
D. O. Rybalka🇺🇸 · E. V. Gorbar🇺🇦 · I. A. Shovkovy🇺🇸
By making use of a covariant formulation of the chiral kinetic theory in the relaxation-time approximation, we derive the first-order dissipative hydrodynamics equations for a charged chiral plasma with background electromagnetic fields. We identify the global equilibrium state for a rotating chiral plasma confined to a cylindrical region with realistic boundary conditions. Then, by using linearized hydrodynamic equations, supplemented by the Maxwell equations, we study hydrodynamic modes of magnetized rotating chiral plasma in the regimes of high temperature and high density. We find that, in both regimes, dynamical electromagnetism has profound effects on the spectrum of propagating modes. In particular, there are only the sound and Alfvén waves in the regime of high temperature, and the plasmons and helicons at high density. We also show that the chiral magnetic wave is universally overdamped because of high electrical conductivity in plasma that causes an efficient screening of charge fluctuations. The physics implications of the main results are briefly discussed.
Comments:
27 pages, 5 figures, published version
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.07608 [pdf]
PRD(2019)·26 citations
09
[Submitted on 19 Jul 2018] (cross-list from hep-th)
Anomaly constraint on massless QCD and the role of Skyrmions in chiral symmetry breaking
Yuya Tanizaki🇺🇸
We discuss consequences of the 't Hooft anomaly matching condition for Quantum Chromodynamics (QCD) with massless fundamental quarks. We derive the new discrete 't Hooft anomaly of massless QCD for generic numbers of color $N_{c}$ and flavor $N_{f}$ , and an exotic chiral-symmetry broken phase without quark-bilinear condensate is ruled out from possible QCD vacua. We show that the $U (1)_{B}$ baryon number symmetry is anomalously broken when the $(Z_{2 N_{f}})_{A}$ discrete axial symmetry and the flavor symmetry are gauged. In the ordinary chiral symmetry breaking, the Skyrmion current turns out to reproduce this 't Hooft anomaly of massless QCD. In the exotic chiral symmetry breaking, however, the anomalous breaking of $U (1)_{B}$ does not take the correct form, and it is inconsistent with anomaly matching. This no-go theorem is based only on symmetries and anomalies, and thus has a wider range of applicability to the QCD phase diagram than the previous one obtained by QCD inequalities. Lastly, as another application, we check that duality of $N = 1$ supersymmetric QCD with $N_{f} \geq N_{c} + 1$ satisfies the new anomaly matching.
Comments:
28 pages;(v2) minor updates;(v3) ref added, appendix added
Subjects:
High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1807.07666 [pdf]
JHEP(2018)·85 citations
10
[Submitted on 19 Jul 2018] (cross-list from hep-th)
Geometrically confined thermal field theory: Finite size corrections and phase transitions
Sylvain Mogliacci🇿🇦 · Isobel Kolbé🇿🇦 · W. A. Horowitz🇿🇦
Motivated by the recent shocking results from RHIC and LHC that show quark-gluon plasma signatures in small systems, we study a simple model of a massless, noninteracting scalar field confined with Dirichlet boundary conditions. We use this system to investigate the finite size corrections to thermal field theoretically derived quantities compared to the usual Stefan-Boltzmann limit of an ideal gas not confined in any direction. Two equivalent expressions with different numerical convergence properties are found for the free energy in $D$ rectilinear spacetime dimensions with $c \leq D - 1$ spatial dimensions of finite extent. We find that the First Law of Thermodynamics generalizes such that the pressure depends on direction but that the Third Law is respected. For systems with finite dimension(s) but infinite volumes, such as a field constrained between two parallel plates or a rectangular tube, the relative fluctuations in energy are zero, and hence the canonical and microcanonical ensembles are equivalent. We present precise numerical results for the free energy, total internal energy, pressure, entropy, and heat capacity of our field between parallel plates, in a tube, and in finite volume boxes of various sizes in 4 spacetime dimensions. For temperatures and system sizes relevant for heavy ion phenomenology, we find large deviations from the Stefan-Boltzmann limit for these quantities, especially for the pressure. Further investigation of an isolated system of fields constrained between parallel plates reveals a divergent isoenergetic compressibility at a critical length $L_{c} \sim 1/ T$ . We have thus discovered a new second order phase transition via a first principles calculation, a transition that is driven by the size of the system.
Comments:
47 pages, 15 figures
Subjects:
High Energy Physics — Theory (hep-th); Quantum Gases (cond-mat.quant-gas); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.07871 [pdf]
PRD(2020)·27 citations
11
[Submitted on 20 Jul 2018] (cross-list from hep-th)
On Bulk Viscosity at Weak and Strong 't Hooft Couplings
Alina Czajka🇨🇦 · Keshav Dasgupta🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Aalok Misra🇮🇳 · Michael Richard🇨🇦 · Karunava Sil🇮🇳
Bulk viscosity is an important transport coefficient that exists in the hydrodynamical limit only when the underlying theory is non-conformal. One example being thermal QCD with large number of colors. We study bulk viscosity in such a theory at low energies and at weak and strong 't Hooft couplings when the temperature is above the deconfinement temperature. The weak coupling analysis is based on Boltzmann equation from kinetic theory whereas the strong coupling analysis uses non-conformal holographic techniques from string and M-theories. Using these, many properties associated with bulk viscosity may be explicitly derived. This is a shortened companion paper that summarizes some of the results of our longer paper arXiv:1807.04713.
Comments:
18 pages, 3 figures, Companion paper
Subjects:
High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.07950 [pdf]
Mod.Phys.Lett.A(2020)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE