Nuclear Theory·nucl-th

Tuesday·July 10, 2018

17 papers—9 primary·8 cross-listed

10
[Submitted on 8 Jul 2018] (cross-list from hep-ph)
Model-Independent Bounds on $R (J / ψ)$
Thomas D. Cohen🇺🇸 · Henry Lamm🇺🇸 · Richard F. Lebed🇺🇸
We present a model-independent bound on $R (J / ψ) \equiv B R (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) / B R (B_{c}^{+} \to J / ψ μ^{+} ν_{μ})$ . This bound is constructed by constraining the form factors through a combination of dispersive relations, heavy-quark relations at zero-recoil, and the limited existing determinations from lattice QCD. The resulting 95\% confidence-level bound, $0.20 \leq R (J / ψ) \leq 0.39$ , agrees with the recent LHCb result at $1.3 σ$ , and rules out some previously suggested model form factors.
Comments:
19 pages, 4 figures, JHEP format, revised to match published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1807.02730 [pdf]
JHEP(2018)·48 citations
11
[Submitted on 8 Jul 2018] (cross-list from hep-th)
Causality and dissipation in relativistic polarizeable fluids
David Montenegro🇧🇷 · Giorgio Torrieri🇧🇷
We analyze the breakdown of causality for the perfect fluid limit in a medium with polarizeability. We show that to restore causality a relaxation term linking vorticity and polarization, analogous to the Israel-Stewart term linking viscous forces and gradients,is required. This term provides a minimum amount of dissipation a locally thermalized relativistic medium with polarizeability must have, independently of its underlying degrees of freedom. For ferromagnetic materials an infrared acausal mode remains, which we interpret as a Banks-Casher mode signaling spontaneous magnetization. With these ingredients, we propose a candidate for a fully causal Lagrangian of a relativistic polarizeable system near the perfect fluid limit.
Comments:
Version accepted for publication, Phys.Rev.D
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.02796 [pdf]
PRD(2019)·102 citations
12
[Submitted on 9 Jul 2018] (cross-list from hep-lat)
Asymptotic behavior of Nambu-Bethe-Salpeter wave functions for scalar systems with a bound state
Shinya Gongyo🇯🇵 · Sinya Aoki🇯🇵
We study the asymptotic behaviors of the Nambu-Bethe-Salpeter (NBS) wave functions, which are important for the HAL QCD potential method to extract hadron interactions, in the case that a bound state exists in the system. We consider the complex scalar particles, two of which lead to the formation of a bound state. In the case of the two-body system, we show that the NBS wave functions for the bound state as well as scattering states in the asymptotic region behave like the wave functions in quantum mechanics, which carry the information of the binding energy as well as the scattering phase shift. This analysis theoretically establishes under some conditions that the HAL QCD potential can correctly reproduce not only the scattering phase shift but also the binding energy. As an extension of the analysis, we also study the asymptotic behaviors of all possible NBS wave functions in the case of the three-body systems, two of which can form a bound states.
Comments:
16 pages; published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.02967 [pdf]
PTEP(2018)·7 citations
13
[Submitted on 9 Jul 2018] (cross-list from hep-ph)
Heavy-flavor flow-harmonics in high-energy nuclear collisions: time-development and eccentricity fluctuations
A. Beraudo🇮🇹 · A. De Pace🇮🇹 · M. Monteno🇮🇹 · M. Nardi🇮🇹 · F. Prino🇮🇹
We study the development of heavy-flavor flow harmonics in high-energy nuclear collisions. The elliptic and triangular flow of heavy-flavor hadrons, arising from the finite impact parameter of the two nuclei and from event-by-event fluctuations of the initial geometry, is analyzed in detail, considering the contribution from particles decoupling from the fireball at various times. We also study the dependence of the flow harmonics on the event-shape fluctuations, considering events belonging to the same centrality class but characterized by very different eccentricities (or vice-versa).
Comments:
Quark-Matter 2018 proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.03180 [pdf]
NPA(2019)·5 citations
14
[Submitted on 9 Jul 2018] (cross-list from hep-ex)
On strangeness in NA61/SHINE
Maciej P. Lewicki (for the NA61/SHINE Collaboration)🇵🇱
NA61/SHINE is a fixed target experiment at the CERN Super-Proton- Synchrotron. The main goals of the experiment are to discover the critical point of strongly interacting matter and to study the properties of the onset of deconfinement. In order to reach these goals, a study of hadron production properties is performed in nucleus-nucleus, proton-proton and proton-nucleus interactions as a function of collision energy and size of the colliding nuclei. In this paper, I will review recent results on strangeness production in p+p, Be+Be and Ar+Sc collisions in the SPS energy range. Kinematic spectra and mean multiplicities of kaons obtained with various analysis methods will be shown. An overview of strangeness production and its dependence on system size in the vicinity of the phase transition will be presented as well.
Comments:
Presented at Excited QCD, Kopaonik, Serbia, 11-15 March 2018
Subjects:
High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1807.03185 [pdf]
Acta Phys.Polon.Supp.(2018)·1 citation
15
[Submitted on 9 Jul 2018] (cross-list from hep-ph)
Phenomenological bound on the viscosity of the hadron resonance gas
Snigdha Ghosh🇮🇳 · Sabyasachi Ghosh🇮🇳 · Sumana Bhattacharyya🇮🇳
We have explored some phenomenological issues during calculations of transport coefficients for hadronic matter, produced in the experiments of heavy ion collisions. Here, we have used an ideal hadron resonance gas model to demonstrate the issues. On the basis of dissipation mechanism, the hadronic zoo is classified into resonance and non-resonance members, who participate in dissipation via strong decay and scattering channels respectively. Imposing our phenomenological restriction, we are able to provide a rough upper and lower bound estimations of transport coefficients. Interestingly, we find that our proposed lower limit estimation for shear viscosity to entropy density ratio is little larger than its quantum lower bound. By taking a simple example, we have demonstrated how our proposed restriction help to tune any estimation of transport coefficients within its numerical band, proposed by us.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.03188 [pdf]
PRC(2018)·17 citations
16
[Submitted on 9 Jul 2018] (cross-list from hep-ph)
Hidden strange pentaquark in constituent quark models
Xuejie Liu🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳
In the framework of the chiral quark model, we investigate the hidden strange pentaquark system of the $N ϕ$ state with the quantum numbers of IJ= $\frac{1}{2}$ $\frac{3}{2}$ . The results show that the $N ϕ$ state can be bound through the interaction of the $σ$ meson exchange plus the effect of the channel coupling, which means that the effect of the channel coupling has an influence on the existence of this bound state.
Comments:
6 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.03195 [pdf]
PRC(2018)·11 citations
17
[Submitted on 9 Jul 2018] (cross-list from astro-ph.HE)
Super-Knee Cosmic Rays from Galactic Neutron Star Merger Remnants
Shigeo S. Kimura🇺🇸 · Kohta Murase🇺🇸 · Peter Mészáros🇺🇸
The detection of gravitational waves and electromagnetic counterparts from a binary neutron star (BNS) merger confirmed that it is accompanied by the launch of fast merger ejecta. Analogous to supernova remnants, forward shocks formed by the interaction of the ejecta with interstellar material will produce high-energy cosmic rays. We investigate the possibility that Galactic neutron star merger remnants (NSMRs) significantly contribute to the observed cosmic rays in the energy range between the knee and the ankle. Using typical parameters obtained by modeling of GW170817, we find that NSMRs can accelerate iron nuclei up to $\sim 500$ PeV. We calculate the cosmic-ray spectrum and composition observed on Earth, and show that the Galactic NSMR scenario can account for the experimental cosmic-ray data in the 20 -- 1000 PeV range. Our model can naturally explain the hardening feature around 20 PeV for total cosmic-ray spectrum, which has been observed by the Telescope Array Low Energy extension and the IceTop air shower array.
Comments:
8 pages, 1 figure, 1 table, accepted for publication in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1807.03290 [pdf]
ApJ(2018)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE