Nuclear Theory·nucl-th

Monday·May 16, 2016

9 papers—2 primary·7 cross-listed

01
[Submitted on 13 May 2016]
Thermalization and hydrodynamization in the color-flux-tube model
Radoslaw Ryblewski🇵🇱
The study of transverse-momentum spectra of quarks and gluons produced by the color electric flux tube decaying through the Schwinger tunneling mechanism is reviewed. The hints for a fast hydrodynamization in the ultra-relativistic heavy-ion collisions are found.
Comments:
Talk presented by Radoslaw Ryblewski at Excited QCD 2016, 6-12 March 2016, Costa da Caparica, Portugal
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1605.04126 [pdf]
Acta Phys.Polon.Supp.(2016)·0 citations
02
[Submitted on 13 May 2016]
A Statistical Approach to Describe Highly Excited Heavy and Superheavy Nuclei
Peng-Hui Chen · Zhao-Qing Feng · Jun-Qing Li · Hong-Fei Zhang
A statistical approach based on the Weisskopf evaporation theory has been developed to describe the de-excitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating $γ$ -ray, light particles (neutrons, protons, $α$ etc) in competition with the binary fission, in which the structure effects (shell correction, fission barrier, particle separation energy) contribute to the processes. The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies. The available data of fusion-evaporation excitation functions in the $^{28}$ Si+ $^{198}$ Pt reaction can be reproduced nicely well within the approach.
Comments:
10 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1605.04208 [pdf]
CPC(2016)·26 citations
03
[Submitted on 12 May 2016] (cross-list from hep-lat)
Rho resonance parameters from lattice QCD
Dehua Guo🇺🇸 · Andrei Alexandru🇺🇸 · Raquel Molina🇺🇸 · Michael Doering🇺🇸
We perform a high-precision calculation of the phase shifts for $π$ - $π$ scattering in the I = 1, J = 1 channel in the elastic region using elongated lattices with two mass-degenerate quark favors ( $N_{f} = 2$ ). We extract the $ρ$ resonance parameters using a Breit-Wigner fit at two different quark masses, corresponding to $m_{π} = 226$ MeV and $m_{π} = 315$ MeV, and perform an extrapolation to the physical point. The extrapolation is based on a unitarized chiral perturbation theory model that describes well the phase-shifts around the resonance for both quark masses. We find that the extrapolated value, $m_{ρ} = 720 (1) (15)$ MeV, is significantly lower that the physical rho mass and we argue that this shift could be due to the absence of the strange quark in our calculation.
Comments:
20 pages, 12 figures, version to appear in PRD
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1605.03993 [pdf]
PRD(2016)·118 citations
04
[Submitted on 13 May 2016] (cross-list from hep-ph)
Vortical fluid and $Λ$ spin correlations in high-energy heavy-ion collisions
Long-Gang Pang (FIAS)🇩🇪 · Hannah Petersen (FIAS and ITP)🇩🇪 · Qun Wang (USTC)🇨🇳 · Xin-Nian Wang (CCNU and LBNL)🇨🇳
Fermions become polarized in a vortical fluid due to spin-vorticity coupling. The spin polarization density is proportional to the local fluid vorticity at the next-to-leading order of a gradient expansion in a quantum kinetic theory. Spin correlations of two $Λ$ -hyperons can therefore reveal the vortical structure of the dense matter in high-energy heavy-ion collisions. We employ a (3+1)D viscous hydrodynamic model with event-by-event fluctuating initial conditions from A MultiPhase Transport (AMPT) model to calculate the vorticity distributions and $Λ$ spin correlations. The azimuthal correlation of the transverse spin is shown to have a cosine form plus an offset due to a circular structure of the transverse vorticity around the beam direction and global spin polarization. The longitudinal spin correlation shows a structure of vortex-pairing in the transverse plane due to the convective flow of hot spots in the radial direction. The dependence on colliding energy, rapidity, centrality and sensitivity to the shear viscosity are also investigated.
Comments:
5 pages in Latex, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1605.04024 [pdf]
PRL(2016)·230 citations
05
[Submitted on 13 May 2016] (cross-list from physics.atom-ph)
Improved limits on interactions of low-mass spin-0 dark matter from atomic clock spectroscopy
Y. V. Stadnik🇦🇺 · V. V. Flambaum🇦🇺
Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently oscillating classical field $ϕ = ϕ_{0} cos (m_{ϕ} t)$ , can induce oscillating variations in the fundamental constants through their interactions with the Standard Model sector. We calculate the effects of such possible interactions, which may include the linear interaction of $ϕ$ with the Higgs boson, on atomic and molecular transitions. Using recent atomic clock spectroscopy measurements, we derive new limits on the linear interaction of $ϕ$ with the Higgs boson, as well as its quadratic interactions with the photon and light quarks. For the linear interaction of $ϕ$ with the Higgs boson, our derived limits improve on existing constraints by up to $2 - 3$ orders of magnitude.
Comments:
6 pages, 5 figures
Subjects:
Atomic Physics (physics.atom-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.04028 [pdf]
PRA(2016)·71 citations
06
[Submitted on 13 May 2016] (cross-list from hep-lat)
Study of the phase diagram of dense two-color QCD within lattice simulation
V. V. Braguta🇷🇺 · E.-M. Ilgenfritz🇷🇺 · A. Yu. Kotov🇷🇺 · A. V. Molochkov🇷🇺 · A. A. Nikolaev🇷🇺
In this paper we carry out a low-temperature scan of the phase diagram of dense two-color QCD with $N_{f} = 2$ quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point $μ = m_{π} /2$ we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with non-zero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase the system is still in confinement, chiral symmetry is restored and the system is very similar to the quarkyonic state predicted by SU( $N_{c}$ ) theory at large $N_{c}$ .
Comments:
12 pages, 12 figures
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.04090 [pdf]
PRD(2016)·93 citations
07
[Submitted on 13 May 2016] (cross-list from hep-ph)
On the Origin of the $X Y Z$ Mesons
A. Valcarce🇪🇸 · J. Vijande🇪🇸
In this talk we present a mechanism giving rise to exotic $X Y Z$ four-quark states in the meson spectra within a constituent quark model approach. We discuss its generalization to five-quark states in the heavy baryon sector. Finally, we revise some other works in the literature and experimental data where this mechanism may be working.
Comments:
6 pages, 2 figures. Talk presented at the Hadron 2015 Conference. To appear in AIP Conference Proceedings
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.04107 [pdf]
AIP Conf.Proc.(2016)·0 citations
08
[Submitted on 13 May 2016] (cross-list from hep-ph)
Deeply bound $Ξ$ tribaryon
H. Garcilazo🇲🇽 · A. Valcarce🇪🇸
We have used realistic local interactions based on the recent update of the strangeness $- 2$ Nijmegen ESC08c potential to calculate the bound state problem of the $Ξ N N$ system in the $(I) J^{P} = (\frac{1}{2}) \frac{3}{2}^{+}$ state. We found that this system presents a deeply bound state lying $13.5$ MeV below the $Ξ d$ threshold. Since in lowest order, pure S $-$ wave configuration, this system can not decay into the open $ΛΛ N$ channel, its decay width is expected to be very small. We have also recalculated the $(I) J^{P} = (\frac{3}{2}) \frac{1}{2}^{+}$ state and we have compared with results of quark-model based potentials.
Comments:
10 pages
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.04108 [pdf]
PRC(2016)·33 citations
09
[Submitted on 13 May 2016] (cross-list from hep-ph)
Initial conditions for hydrodynamics from weakly coupled pre-equilibrium evolution
Liam Keegan🇨🇭 · Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇺🇸 · Derek Teaney🇺🇸
We use effective kinetic theory, accurate at weak coupling, to simulate the pre-equilibrium evolution of transverse energy and flow perturbations in heavy-ion collisions. We provide a Green function which propagates the initial perturbations to the energy-momentum tensor at a time when hydrodynamics becomes applicable. With this map, the complete pre-thermal evolution from saturated nuclei to hydrodynamics can be modelled in a perturbatively controlled way.
Comments:
25 pages, 9 figures (prepared for submission to JHEP). Differences from version 1: updated figures 3(b), 5, 7, 8 and 9, replaced appendix A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.04287 [pdf]
JHEP(2016)·100 citations

Affiliations

first authorsco-authorsvia INSPIRE