Nuclear Theory·nucl-th

Tuesday·July 11, 2017

10 papers—5 primary·5 cross-listed

01
[Submitted on 7 Jul 2017]
Are minimal conditions for collectivity met in e+e- collisions?
J.L. Nagle🇺🇸 · R. Belmont🇺🇸 · K. Hill🇺🇸 · J. Orjuela Koop🇺🇸 · D.V. Perepelitsa🇺🇸 · P. Yin🇺🇸 · Z-W. Lin🇺🇸 · D. McGlinchey🇺🇸
Signatures of collective behavior have been measured in highly relativistic p+p collisions, as well as in p+A, d+A, and 3He+A collisions. Numerous particle correlation measurements in these systems have been successfully described by calculations based on viscous hydrodynamic and transport models. These observations raise the question of the minimum necessary conditions for a system to exhibit collectivity. Recently, numerous scientists have raised the question of whether the quarks and gluons generated in e+e- collisions may satisfy these minimum conditions. In this paper we explore possible signatures of collectivity, or lack thereof, in e+e- collisions utilizing A Multi-Phase Transport (AMPT) framework which comprises melted color strings, parton scattering, hadronization, and hadron re-scattering.
Comments:
7 pages, 6 figures, submitted for publication
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.02307 [pdf]
PRC(2018)·36 citations
02
[Submitted on 9 Jul 2017]
Rapidity dependence of proton cumulants and correlation functions
Adam Bzdak🇵🇱 · Volker Koch🇺🇸
The dependence of multi-proton correlation functions and cumulants on the acceptance in rapidity and transverse momentum is studied. We find that the preliminary data of various cumulant ratios are consistent, within errors, with rapidity and transverse momentum independent correlation functions. However, rapidity correlations which moderately increase with rapidity separation between protons are slightly favored. We propose to further explore the rapidity dependence of multi-particle correlation functions by measuring the dependence of the integrated reduced correlation functions as a function of the size of the rapidity window.
Comments:
13 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1707.02640 [pdf]
PRC(2017)·37 citations
03
[Submitted on 9 Jul 2017]
Neutron stars in the large- $N_{c}$ limit
Francesco Giacosa🇵🇱 · Giuseppe Pagliara🇮🇹
We study the phase transition from dense baryonic matter to dense quark matter within the large- $N_{c}$ limit. By using simple constant speed of sound equations of state for the two phases, we derive the scaling with $N_{c}$ of the critical quark chemical potential $μ_{c}^{crit}$ for this phase transition. While quark matter is strongly suppressed at large $N_{c}$ , the phase transition at a large but finite density could nevertheless be important to determine the maximum mass of compact stars. In particular, in the range $3 \leq N_{c} ≲ 5.5$ the quark phase would take place in compact stars and would lead to the formation of an unstable branch of hybrid stars. As a consequence, the maximum mass is restricted to the range $2.1 M_{⊙} < M_{ma x} < 3 M_{⊙}$ . For larger value of $N_{c}$ , the phase transition would occur at densities too high to be reached in the core of compact stars. However, the very requirement that it occurs (although at a very large density) translates into interesting constraints on the stiffness of the baryonic phase: its speed of sound must exceed $1/3$ .
Comments:
8 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1707.02644 [pdf]
NPA(2017)·6 citations
04
[Submitted on 10 Jul 2017]
Chiral phase transition in linear sigma model with non-extensive statistical mechanics
Ke-Ming Shen🇨🇳 · Hui Zhang🇨🇳 · De-Fu Hou🇨🇳 · Ben-Wei Zhang🇨🇳 · En-Ke Wang🇨🇳
From the non-extensive statistical mechanics, we investigate the chiral phase transition at finite temperature $T$ and baryon chemical potential $μ_{B}$ in the framework of the linear sigma model. The corresponding non-extensive distribution, based on Tsallis' statistics, is characterized by a dimensionless non-extensive parameter, $q$ , and the results in the usual Boltzmann-Gibbs case are recovered when $q \to 1$ . The thermodynamics of the linear sigma model and its correspodning phase diagram are analysed. At high temperature region, the critical temperature $T_{c}$ is shown to decrease with increasing $q$ from the phase diagram in the $(T, μ)$ plane. However, larger values of $q$ causes the rise of $T_{c}$ at low temperature but high chemical potential. Moreover, it is found that $μ$ different from zero corresponds to a first-order phase transition while $μ = 0$ to a crossover one. The critical endpoint (CEP) carries higher chemical potential but lower temperature with $q$ increasing due to the non-extensive effects.
Comments:
6 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.02735 [pdf]
Adv.High Energy Phys.(2017)·16 citations
05
[Submitted on 10 Jul 2017]
Light-nuclei spectra from chiral dynamics
M. Piarulli · A. Baroni · L. Girlanda · A. Kievsky · A. Lovato · Ewing Lusk · L.E. Marcucci · Steven C. Pieper · R. Schiavilla · M. Viviani · R.B. Wiringa
A major goal of nuclear theory is to explain the spectra and stability of nuclei in terms of effective many-body interactions amongst the nucleus' constituents-the nucleons, i.e., protons and neutrons. Such an approach, referred to below as the basic model of nuclear theory, is formulated in terms of point-like nucleons, which emerge as effective degrees of freedom, at sufficiently low energy, as a result of a decimation process, starting from the fundamental quarks and gluons, described by Quantum Chromodynamics (QCD). A systematic way to account for the constraints imposed by the symmetries of QCD, in particular chiral symmetry, is provided by chiral effective field theory, in the framework of a low-energy expansion. Here we show, in quantum Monte Carlo calculations accurate to $\leq 2%$ of the binding energy, that two- and three-body chiral interactions fitted {\sl only} to bound- and scattering-state observables in, respectively, the two- and three-nucleon sectors, lead to predictions for the energy levels and level ordering of nuclei in the mass range $A$ =4-12 in very satisfactory agreement with experimental data. Our findings provide strong support for the fundamental assumptions of the basic model, and pave the way to its systematic application to the electroweak structure and response of these systems as well as to more complex nuclei.
Comments:
21 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.02883 [pdf]
PRL(2018)·176 citations
06
[Submitted on 8 Jul 2017] (cross-list from hep-th)
Anomalous current from covariant Wigner functions
George Prokhorov🇷🇺 · Oleg Teryaev🇷🇺
We consider accelerated and rotating media of weakly interacting fermions in local thermodynamic equilibrium. Kinetic properties of this media are described by covariant Wigner function calculated on the basis of relativistic distribution function of particles with spin. We obtain the formulae for axial current beyond the approximation of smallness of thermal vorticity tensor and chemical potential and calculate its divergence. In the massless limit higher order terms in vorticity and chemical potential compensate each other with only the low-order contributions surviving. It is shown, that axial current gets a topological component along the 4-acceleration vector. The similarity between different approaches to baryon polarisation is established.
Comments:
10 pages, no figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1707.02491 [pdf]
PRD(2018)·30 citations
07
[Submitted on 9 Jul 2017] (cross-list from hep-ph)
Heavy sterile neutrino in dark matter searches
Paraskevi C. Divari🇬🇷 · John D. Vergados🇬🇷
Sterile neutrinos are possible dark matter candidates. We examine here possible detection mechanisms, assuming that the neutrino has a mass of about 50 keV and couples to the ordinary neutrino. Even though this neutrino is quite heavy, it is non relativistic with a maximum kinetic energy of 0.1 eV. Thus new experimental techniques are required for its detection. We estimate the expected event rate in the following cases: i) Measure electron recoils in the case of materials with very low electron binding. ii) Low temperature crystal bolometers. iii) Spin induced atomic excitations at very low temperatures, leading to a characteristic photon spectrum. iv) Observation of resonances in antineutrino absorption by a nucleus undergoing electron capture. v) Neutrino induced electron events beyond the end point energy of beta decaying systems, e.g. in the tritium decay studied by KATRIN.
Comments:
17 pages, 8 figures ; revised figures, corrected typos, additional comments ; results unchanged
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1707.02550 [pdf]
Adv.High Energy Phys.(2018)·6 citations
08
[Submitted on 10 Jul 2017] (cross-list from hep-ph)
Magnetic moments of the doubly charmed and bottomed baryons
Hao-Song Li🇨🇳 · Lu Meng🇨🇳 · Zhan-Wei Liu🇨🇳 · Shi-Lin Zhu🇨🇳
The chiral corrections to the magnetic moments of the spin- $\frac{1}{2}$ doubly charmed baryons are systematically investigated up to next-to-next-to-leading order with heavy baryon chiral perturbation theory (HBChPT). The numerical results are calculated up to next-to-leading order: $μ_{Ξ_{cc}^{++}} = - 0.25 μ_{N}$ , $μ_{Ξ_{cc}^{+}} = 0.85 μ_{N}$ , $μ_{Ω_{cc}^{+}} = 0.78 μ_{N}$ . We also calculate the magnetic moments of the other doubly heavy baryons, including the doubly bottomed baryons (bbq) and the doubly heavy baryons containing a light quark, a charm quark and a bottom quark ( ${b c} q$ and $[b c] q$ ): $μ_{Ξ_{bb}^{0}} = - 0.84 μ_{N}$ , $μ_{Ξ_{bb}^{-}} = 0.26 μ_{N}$ , $μ_{Ω_{bb}^{-}} = 0.19 μ_{N}$ , $μ_{Ξ_{{b c} q}^{+}} = - 0.54 μ_{N}$ , $μ_{Ξ_{{b c} q}^{0}} = 0.56 μ_{N}$ , $μ_{Ω_{{b c} q}^{0}} = 0.49 μ_{N}$ , $μ_{Ξ_{[b c] q}^{+}} = 0.69 μ_{N}$ , $μ_{Ξ_{[b c] q}^{0}} = - 0.59 μ_{N}$ , $μ_{Ω_{[b c] q}^{0}} = 0.24 μ_{N}$ .
Comments:
11 pages, 2 figures
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:
1707.02765 [pdf]
PRD(2017)·66 citations
09
[Submitted on 10 Jul 2017] (cross-list from hep-ph)
Probing Saturation Physics in the Real Compton Scattering at Ultraperipheral $pP b$ Collisions
V. P. Goncalves🇧🇷 · F. S. Navarra🇧🇷 · D. Spiering🇧🇷
The Real Compton Scattering in ultraperipheral $pP b$ collisions at RHIC and LHC energies is investigated and predictions for the squared transverse momentum ( $t$ ) and rapidity ( $Y$ ) distributions are presented. The scattering amplitude is assumed to be given by the sum of the Reggeon and Pomeron contributions and the Pomeron one is described by the Color Dipole formalism taking into account the non - linear (saturation) effects in the QCD dynamics. We demonstrate that the behaviour of the cross sections at large -- $t$ and/or $Y$ is dominated by the Pomeron contribution and is strongly affected by the non -- linear effects present in the QCD dynamics. These results indicate that a future experimental analysis of this process can be useful to probe the QCD dynamics at high energies.
Comments:
8 pages, 8 figures. Two new figures included. Version published in Physics Letters B
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1707.02806 [pdf]
PLB(2017)·2 citations
10
[Submitted on 10 Jul 2017] (cross-list from hep-th)
One-loop QCD thermodynamics in a strong homogeneous and static magnetic field
Shubhalaxmi Rath🇮🇳 · Binoy Krishna Patra🇮🇳
We have studied how the equation of state of thermal QCD with two light flavours is modified in strong magnetic field by calculating the thermodynamic observables of hot QCD matter up to one-loop, where the magnetic field affects mainly the quark contribution and the gluonic part is largely unaffected except for the softening of the screening mass due to the strong magnetic field. To begin with the effect of magnetic field on the thermodynamics, we have first calculated the pressure of a thermal QCD medium in strong magnetic field limit (SML), where the pressure at fixed temperature increases with the magnetic field faster than the increase with the temperature at constant magnetic field. This can be envisaged from the dominant scale of thermal medium in SML, which is the magnetic field, like the temperature in thermal medium in absence of strong magnetic field. Thus although the presence of strong magnetic field makes the pressure of hot QCD medium harder but the increase of pressure with respect to the temperature becomes less steeper. Corroborated to the above observations, the entropy density is found to decrease with the temperature in the ambience of strong magnetic field which resonates with the fact that the strong magnetic field restricts the dynamics of quarks in two dimensions, hence the phase space gets squeezed resulting the reduction of number of microstates. Moreover the energy density is seen to decrease and the speed of sound of thermal QCD medium is increased in the presence of strong magnetic field. These crucial findings in strong magnetic field could have phenomenological implications in heavy ion collisions because the expansion dynamics of the medium produced in noncentral ultrarelativistic heavy ion collisions is effectively controlled by both the energy density and the speed of sound.
Comments:
42 pages, 6 figures and 2 diagrams
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1707.02890 [pdf]
JHEP(2017)·62 citations

Affiliations

first authorsco-authorsvia INSPIRE