Nuclear Theory·nucl-th

Tuesday·December 4, 2018

10 papers—6 primary·4 cross-listed

01
[Submitted on 1 Dec 2018]
$η$ photoproduction off the deuteron and low-energy $η$ -nucleon interaction
S.X. Nakamura (Univ. Cruzeiro do Sul)🇧🇷 · H. Kamano (RCNP, Osaka Univ.)🇯🇵 · T. Ishikawa (ELPH, Tohoku Univ.)🇯🇵
We study $η$ photoproduction off the deuteron ( $γ d \to η p n$ ) at a special kinematics: $\sim 0.94$ GeV of the photon beam energy and $\sim 0^{\circ}$ of the scattering angle of the proton. This kinematics is ideal to extract the low-energy $η$ -nucleon scattering parameters such as $a_{η N}$ (scattering length) and $r_{η N}$ (effective range) because the $η$ -nucleon elastic scattering is significantly enhanced. We show that if a ratio $R$ , the $γ d \to η p n$ cross section divided by the $γ p \to η p$ cross section convoluted with the proton momentum distribution in the deuteron, is measured with 5% error, $Re [a_{η N}]$ ( $Re [r_{η N}]$ ) can be determined at the precision of $\sim \pm$ 0.1 fm ( $\sim \pm$ 0.5 fm), significantly narrowing down the currently estimated range of the parameters. The measurement is ongoing at the Research Center for Electron Photon Science (ELPH), Tohoku University.
Comments:
4 pages, 5 figures, Contribution to the Proceedings for 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japan
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1812.00168 [pdf]
JPS Conf.Proc.(2019)·0 citations
02
[Submitted on 1 Dec 2018]
Wigner function approach to polarization-vorticity coupling and hydrodynamics with spin
Avdhesh Kumar🇵🇱
Newly introduced equilibrium Wigner functions for particles with spin one-half are used in the semi-classical kinetic equations to study a possible relation between thermal vorticity and spin polarization. It is shown that in global equilibrium both the thermal-vorticity and spin polarization tensors are constant but not necessarily equal. In the case of local equilibrium, we define a procedure leading to hydrodynamic equations with spin. We introduce such equations for the de~Groot, van~Leeuwen, and van~Weert (GLW) formalism as well as for the canonical scheme (these two frameworks differ by the definitions of the energy-momentum and spin tensors). It is found that the GLW and canonical versions are connected by a pseudo-gauge transformation.
Comments:
8 pages, contribution to the XIII Quark Confinement and the Hadron Spectrum (Confinement2018) conference proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1812.00217 [pdf]
PoS(2018)·6 citations
03
[Submitted on 2 Dec 2018]
The production of $b b ˉ$ dijet in heavy-ion collisions at the LHC
Sa Wang🇨🇳 · Wei Dai🇨🇳 · Shan-Liang Zhang🇨🇳 · Ben-Wei Zhang🇨🇳 · Enke Wang🇨🇳
We report our recent theoretical calculations for $b b ˉ$ dijet production in high-energy nuclear collisions. The NLO+parton shower (PS) event generator SHERPA has been employed to provide the pp baseline of $b b ˉ$ dijet production. A framework which combines Langevin transport equation to describe the evolution of heavy quarks and the higher-twist scheme to consider the inelastic energy loss of both light and heavy partons has been implemented. Within this framework, we present the theoretical result of transverse momentum imbalance $x_{J} = p_{T 1} / p_{T 2}$ both for inclusive dijet and $b b ˉ$ dijet in Pb+Pb collision at 5.02 TeV. The energy loss of b jet would shift $x_{J}$ to smaller value relative to p+p reference which is consistent with the CMS data. In addition, we show the medium modification for angular correlation of $b b ˉ$ dijet in A+A collision at $s_{N N} = 5.02$ ~TeV. We observe a stronger suppression in small $Δ ϕ = ∣ ϕ_{b 1} - ϕ_{b 2} ∣$ region where the gluon splitting processes dominate relative to large $Δ ϕ$ region. The difference leads to a modest suppression on near side ( $Δ ϕ \sim 0$ ) and enhancement on away side ( $Δ ϕ \sim π$ ).
Comments:
4 pages, 4 figures, Parallel talk presented at Hard Probes 2018
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1812.00391 [pdf]
PoS(2018)·3 citations
04
[Submitted on 3 Dec 2018]
Simultaneous Fitting of Neutron Star Structure and Cooling Data
Spencer Beloin🇺🇸 · Sophia Han🇺🇸 · Andrew W. Steiner🇺🇸 · Khorgolkhuu Odbadrakh🇺🇸
Using a model for the equation of state and composition of dense matter and the magnitude of singlet proton superconductivity and triplet neutron superfluidity, we perform the first simultaneous fit of neutron star masses and radii determined from observations of quiescent low-mass x-ray binaries and luminosities and ages determined from observations of isolated neutron stars. We find that the Vela pulsar strongly determines the values inferred for the superfluid/superconducting gaps and the neutron star radius. We find, regardless of whether or not the Vela pulsar is included in the analysis, that the threshold density for the direct Urca process lies between the central density of 1.7 and 2 solar mass neutron stars. We also find that two solar mass stars are unlikely to cool principally by the direct Urca process because of the suppression by neutron triplet superfluidity.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1812.00494 [pdf]
PRC(2019)·23 citations
05
[Submitted on 20 Nov 2018]
Application of resonant decay method for compound-systems at analysis inclusive spectra in high-energy nuclear reactions
S.A. Omelchenko · V.S. Olkhovsky
It is shown, that the exponential decrease of the energy spectra of the fragments with growing its energy, which does not depend from the fragment type, targets, projectiles and projectile energies, and which sometimes accompanied slight oscillations, can be explained by the phenomenon of time resonances. These time resonances correspond to decay of intermediate excited nuclear composite system. For the first time, expressions for the decay rate and the probability of survival of such system as a function of time are obtained. Inclusive spectra for two real high-energy nuclear reactions are calculated.
Comments:
8 pages, 5 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.00747 [pdf]
0 citations
06
[Submitted on 3 Dec 2018]
Single-particle structure of the N = 20 and N = 28 isotones within the dispersive optical model
O.V. Bespalova · A.A. Klimochkina
The neutron single-particle characteristics of the N = 20, 28 isotones at 8 < Z < 30 was calculated within the dispersive optical model. The global parameters of the spin-orbit and imaginary parts of the potential as well as surface absorption independent on neutron-proton asymmetry and increased diffuseness at large neutron excess were used in the calculations. The suitability of the global parameters to predict the evolution of the neutron single-particle structure of nuclei near the neutron drip line was investigated. The following results are in agreement with the available experimental data: the reduction of the particle-hole energy gaps, the degeneration of the 1f7/2 and 2p states and then a change in the 1f7/2 , 2p3/2 level sequence and more rapid reduction of the 2p-splitting in comparison with the 1f-splitting with decreasing Z. The predictive power of the dispersive optical model with respect to neutron-rich nuclei is demonstrated.
Comments:
17 pages, 10 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1812.00845 [pdf]
Moscow Univ.Phys.Bull.(2018)·0 citations
07
[Submitted on 2 Dec 2018] (cross-list from hep-ph)
Recent Progress in QCD Condensate Evaluations and Sum Rules
Philipp Gubler🇯🇵 · Daisuke Satow🇯🇵
We review the recent status of the QCD sum rule approach to study the properties of hadrons in vacuum and in hot or dense matter. Special focus is laid on the progress made in the evaluation of the QCD condensates, which are the input of all QCD sum rule calculations, and for which much new information has become available through high precision lattice QCD calculations, chiral perturbation theory and experimental measurements. Furthermore, we critically examine common analysis methods for QCD sum rules and contrast them with potential alternative strategies. The status of QCD sum rule studies investigating the modification of hadrons at finite density as well as recent derivations of exact sum rules applicable to finite temperature spectral functions, are also reviewed.
Comments:
106 pages, 25 figures, 7 tables, matches published version in Progress in Particle and Nuclear Physics, 2019
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1812.00385 [pdf]
PPNP(2019)·136 citations
08
[Submitted on 2 Dec 2018] (cross-list from cond-mat.quant-gas)
Four-Body Scale in Universal Few-Boson Systems
Betzalel Bazak🇮🇱 · Johannes Kirscher🇺🇸 · Sebastian König🇩🇪 · Manuel Pavón Valderrama🇨🇳 · Nir Barnea🇮🇱 · Ubirajara van Kolck🇫🇷
The role of an intrinsic four-body scale in universal few-boson systems is the subject of active debate. We study these systems within the framework of effective field theory. For systems of up to six bosons we establish that no four-body scale appears at leading order (LO). However, we find that at next-to-leading (NLO) order a four-body force is needed to obtain renormalized results for binding energies. With the associated parameter fixed to the binding energy of the four-boson system, this force is shown to renormalize the five- and six-body systems as well. We present an original ansatz for the short-distance limit of the bosonic $A$ -body wave function from which we conjecture that new $A$ -body scales appear at N $^{A - 3}$ LO. As a specific example, calculations are presented for clusters of helium atoms. Our results apply more generally to other few-body systems governed by a large scattering length, such as light nuclei and halo states, the low-energy properties of which are independent of the detailed internal structure of the constituents.
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
1812.00387 [pdf]
PRL(2019)·66 citations
09
[Submitted on 3 Dec 2018] (cross-list from cond-mat.str-el)
Functional-renormalization-group aided density-functional analysis for the correlation energy of the two-dimensional homogeneous electron gas
Takeru Yokota🇯🇵 · Tomoya Naito🇯🇵
The functional-renormalization-group aided density-functional theory (FRG-DFT) is applied to the two-dimensional homogeneous electron gas (2DHEG). The correlation energy of the 2DHEG is derived as a function of the Wigner-Seitz radius $r_{s}$ directly. We find that our correlation energy completely reproduces the exact behavior at the high-density limit. For finite density, the result of FRG-DFT shows good agreement with the Monte Carlo (MC) results in the high-density region, although the discrepancy between FRG-DFT and MC results becomes larger as the system becomes more dilute. Our study is the first example in which the FRG-DFT is applied to more-than-one-dimensional models, and shows that the FRG-DFT is a feasible and promising method even for the analysis of realistic models for quantum many-body systems.
Comments:
10 pages, 1 figure, 1 table
Subjects:
Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1812.00588 [pdf]
PRB(2019)·16 citations
10
[Submitted on 3 Dec 2018] (cross-list from hep-ph)
Neutral meson properties in hot and magnetized quark matter: a new magnetic field independent regularization scheme applied to NJL-type model
Sidney S. Avancini🇧🇷 · Ricardo L. S. Farias🇧🇷 · William R. Tavares🇧🇷
A magnetic field independent regularization scheme (zMFIR) based on the Hurwitz-Riemann zeta function is introduced. The new technique is applied to the regularization of the mean-field thermodynamic potential and mass gap equation within the SU(2) Nambu-Jona-Lasinio model in a hot and magnetized medium. The equivalence of the new and the standard MFIR scheme is demonstrated. The neutral meson pole mass is calculated in a hot and magnetized medium and the advantages of using the new regularization scheme are shown.
Comments:
14 pages, 4 figures, replaced with updated version matching the published one
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1812.00945 [pdf]
PRD(2019)·81 citations

Affiliations

first authorsco-authorsvia INSPIRE