Nuclear Theory·nucl-th

Friday·September 30, 2016

11 papers—4 primary·7 cross-listed

01
[Submitted on 28 Sept 2016]
Probing the QCD phase diagram with dileptons - a study using coarse-grained transport dynamics
Stephan Endres🇩🇪 · Hendrik van Hees🇩🇪 · Marcus Bleicher🇩🇪
Dilepton production in heavy-ion collisions at various energies is studied using coarse-grained transport simulations. Microscopic output from the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model is hereby put on a grid of space-time cells which allows to extract the local temperature and chemical potential in each cell via an equation of state. The dilepton emission is then calculated applying in-medium spectral functions from hadronic many-body theory and partonic production rates based on lattice calculations. The comparison of the resulting spectra with experimental data shows that the dilepton excess beyond the decay contributions from a hadronic cocktail reflects the trajectory of the fireball in the $T - μ_{B}$ plane of the QCD phase diagram.
Comments:
5 pages, 2 figures. Contribution for the proceedings of the 10th International Conference on Critical Point and Onset of Deconfinement (CPOD 2016)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1609.09140 [pdf]
Acta Phys.Polon.Supp.(2017)·2 citations
02
[Submitted on 29 Sept 2016]
New dynamic critical phenomena in nuclear and quark superfluids
Noriyuki Sogabe🇯🇵 · Naoki Yamamoto🇯🇵
We study the dynamic critical phenomena near the possible high-density QCD critical point inside the superfluid phase of nuclear and quark matter. We find that this critical point belongs to a new dynamic universality class beyond the conventional classification by Hohenberg and Halperin. We show that the speed of the superfluid phonon vanishes at the critical point and that the dynamic critical index is $z \approx 2$ .
Comments:
9 pages, 1 figure; v2: published version
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1609.09214 [pdf]
PRD(2017)·7 citations
03
[Submitted on 29 Sept 2016]
In-medium properties of the phi meson with phi N resonant contributions
Daniel Cabrera🇪🇸 · Astrid N. Hiller Blin🇪🇸 · Manuel J. Vicente Vacas🇪🇸
Nuclear production experiments report missing absorption processes of the in-medium phi meson. Contributions arising from the K-bar K cloud have already been widely studied, and therefore we investigate the phi-meson properties in cold nuclear matter with the additional inclusion of resonant phi N interactions. Two models are considered which dynamically generate N*-like states close to the phi N threshold. We find that these states, together with the non-resonant part of the amplitude, contribute to the phi self-energy with the same order of magnitude as the K-bar K effects. At non-vanishing nuclear density, both models lead to an additional in-medium broadening of the phi, up to around 50 MeV. Furthermore, at least one of the models is compatible with a mass shift to lower energies of up to 35 MeV at threshold and normal matter density. Finally, a double-peak structure appears in the spectral function due to the mixing of resonance-hole modes with the $ϕ$ quasi-particle peak. These results converge into the direction of the experimental findings.
Comments:
Proceedings for the conference MENU 2016, Kyoto, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1609.09371 [pdf]
JPS Conf.Proc.(2017)·3 citations
04
[Submitted on 29 Sept 2016]
Static critical fluctuations on the freeze-out surface
Lijia Jiang🇨🇳 · Pengfei Li🇨🇳 · Huichao Song🇨🇳
In this proceeding, we summarize the main results of our recent paper, which introduces a freeze-out scheme to the dynamical models near the QCD critical point. Within such framework of static critical fluctuations, the Beam Energy Scan (BES) data of $C_{4}$ and $κ σ^{2}$ for net protons within different $p_{T}$ ranges can be roughly described. Besides, the momentum acceptance dependence of higher cumulants at lower collision energies can also be qualitatively described. However, $C_{2}$ and $C_{3}$ are always over-predicted due to the positive static critical fluctuations.
Comments:
5 pages, 3 figures, CPOD proceeding
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1609.09385 [pdf]
Acta Phys.Polon.Supp.(2017)·2 citations
05
[Submitted on 14 Sept 2016] (cross-list from hep-lat)
Applying the relativistic quantization condition to a three-particle bound state in a periodic box
Maxwell T. Hansen🇩🇪 · Stephen R. Sharpe🇺🇸
Using our recently developed relativistic three-particle quantization condition, we study the finite-volume energy shift of a spin-zero three-particle bound state. We reproduce the result obtained using non-relativistic quantum mechanics by Meissner, Rios and Rusetsky, and generalize the result to a moving frame.
Comments:
20 pages, no figures, v2: fixed issues with special characters in references, v3: minor rewording, version appearing in PRD
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1609.04317 [pdf]
PRD(2017)·61 citations
06
[Submitted on 28 Sept 2016] (cross-list from hep-ph)
$μ^{-}$ - $e^{+}$ conversion in upcoming LFV experiments
Tanja Geib🇩🇪 · Alexander Merle🇩🇪 · Kai Zuber🇩🇪
We present an illustrative discussion of the physics potential of $μ^{-}$ - $e^{+}$ conversion. We point out that this process, although much less frequently studied than the related but much more popular processes of $μ^{-}$ - $e^{-}$ conversion and neutrinoless double beta decay, in fact is a promising alternative possibility to detect both lepton flavour and number violation. However, for this goal to be reached, a combined effort of experiments and theory, both in nuclear and particle physics, is necessary to advance. The aim of this paper is to be an "appetiser" to trigger such an initiative.
Comments:
16 pages, 4 figures, Slightly more precise notation and terminology compared to published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1609.09088 [pdf]
PLB(2017)·38 citations
07
[Submitted on 29 Sept 2016] (cross-list from hep-ph)
Dissociation of large transverse-momentum prompt J/psi produced in Pb-Pb collisions at the LHC
Shi-Tao Ji🇨🇳 · Xiao-Ming Xu🇨🇳 · H. J. Weber🇺🇸
A collision of a light meson and a charmonium produces quarks and antiquarks first, then the charm quark fragments into a charmed hadron, and finally three or more mesons are produced. This is the mechanism that we consider and propose to understand the prompt-J/psi nuclear modification factor in the range of J/psi transverse momentum from 10 GeV/c to 18 GeV/c, as measured by the CMS Collaboration and the ATLAS Collaboration. Unpolarized cross sections are derived and calculated for the reactions pion+charmonium ->H_c+X with H_c being a charmed meson. Numerical cross sections are parametrized and used to calculate the dissociation rate of charmonium in the interaction with pions in hadronic matter. The momentum dependence of the rate obtained is so as to lead to a decreasing charmonium nuclear modification factor with increasing transverse momentum.
Comments:
30 pages, LaTex; 1 added figure and table
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.09187 [pdf]
NPA(2017)·4 citations
08
[Submitted on 29 Sept 2016] (cross-list from hep-ph)
Analysis of Dalitz decays with intrinsic parity violating interactions in resonance chiral perturbation theory
Daiji Kimura🇯🇵 · Takuya Morozumi🇯🇵 · Hiroyuki Umeeda🇯🇵
Observables of light hadron decays are analyzed in a model of chiral Lagrangian which includes resonance fields of vector mesons. In particular, transition form factors are investigated for Dalitz decays of $V \to P l^{+} l^{-}$ and $P \to γ l^{+} l^{-}$ $(V = 1^{-}, P = 0^{-})$ . Moreover, the differential decay width of $P \to π^{+} π^{-} γ$ and the partial widths of $P \to 2 γ, V \to P γ, η^{'} \to V γ, ϕ (1020) \to ω (782) π^{0}$ and $V \to 3 P$ are also calculated. In this study, we consider a model which contains octet and singlet fields as representation of $S U (3)$ . As an extension of chiral perturbation theory, we include 1-loop ordered interaction terms. For both pseudoscalar and vector meson, we evaluate mixing matrices in which isospin/ $S U (3)$ breaking is taken into account. Furthermore, intrinsic parity violating interactions are considered with singlet fields. For parameter estimation, we carry out $χ^{2}$ fittings in which a spectral function of $τ$ decays, vector meson masses, decay widths of $V \to P γ$ and transition form factor of $V \to P l^{+} l^{-}$ are utilized as input data. Using the estimated parameter region in the model, we give predictions for decay widths and transition form factors of intrinsic parity violating decays. As further model predictions, we calculate the transition form factors of $ϕ (1020) \to π^{0} l^{+} l^{-}$ and $η^{'} \to γ l^{+} l^{-}$ in the vicinity of resonance regions, taking account of the contribution for intermediate $ρ (770)$ and $ω (782)$ .
Comments:
73 pages, 17 figures, 13 tables. Version accepted in PTEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.09235 [pdf]
PTEP(2018)·6 citations
09
[Submitted on 29 Sept 2016] (cross-list from cond-mat.quant-gas)
Level rearrangement in exotic-atom-like three-body systems
Jean-Marc Richard🇫🇷 · Claude Fayard🇫🇷
We study systems of three bosons bound by a long-range interaction supplemented by a short-range potential of variable strength. This generalizes the usual two-body exotic atoms where the Coulomb interaction is modified by nuclear forces at short distances. The energy shift due to the short-range part of the interaction combines two-body terms similar to the ones entering the Trueman-Deser formula, and three-body contributions. A sudden variation of the energy levels is observed near the coupling thresholds of the short-range potential. But the patterns of rearrangement are significantly modified as compared to the two-body case.
Comments:
6 pages, 4 figures, pdflatex, calculations refined, comments and refs. added, to appear in Phys. Lett. A
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
1609.09350 [pdf]
PLA(2017)·2 citations
10
[Submitted on 29 Sept 2016] (cross-list from hep-ph)
Heavy-Meson Decay Constants: Isospin Breaking from QCD Sum Rules
Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Silvano Simula🇮🇹
Compared with lattice QCD, isospin breaking of heavy-meson decay constants from QCD sum rules agrees for $D$ mesons but disagrees (by a factor of four) for $B$ mesons.
Comments:
8 pages, 2 figures, talk presented at "Quark Confinement and the Hadron Spectrum XII" (28 August - 3 September 2016, Thessaloniki, Greece)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1609.09388 [pdf]
EPJ Web Conf.(2017)·2 citations
11
[Submitted on 29 Sept 2016] (cross-list from cond-mat.quant-gas)
Tan's contact and the phase distribution of repulsive Fermi gases: Insights from QCD noise analyses
William J. Porter🇺🇸 · Joaquín E. Drut🇺🇸
Path-integral analyses originally pioneered in the study of the complex-phase problem afflicting lattice calculations of finite-density quantum chromodynamics are generalized to non-relativistic Fermi gases with repulsive interactions. Using arguments similar to those previously applied to relativistic theories, we show that the analogous problem in nonrelativistic systems manifests itself naturally in Tan's contact as a nontrivial cancellation between terms with varied dependence on extensive thermodynamic quantities. We analyze that case under the assumption of gaussian phase distribution, which is supported by our Monte Carlo calculations and perturbative considerations. We further generalize these results to observables other than the contact, as well as to polarized systems and systems with fixed particle number. Our results are quite general in that they apply to repulsive multi-component fermions, are independent of dimensionality or trapping potential, and hold in the ground state as well as at finite temperature.
Comments:
6 pages, 1 figure
Subjects:
Quantum Gases (cond-mat.quant-gas); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1609.09401 [pdf]
PRA(2017)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE