Nuclear Theory·nucl-th
11 papers—5 primary·6 cross-listed
[Submitted on 6 Oct 2015] (cross-list from hep-ph)
transitions in a medium followed by decay and regeneration of -component are considered by means of perturbation theory. It is shown that in the previous calculations the problem different from regeneration is solved.
[Submitted on 13 Jan 2016] (cross-list from astro-ph.HE)
Sho Fujibayashi · Takashi Yoshida · Yuichiro Sekiguchi
We investigate the nucleosynthesis process in high-entropy () and very fast-expanding () materials. In such a material with the electron fraction near 0.5, an interesting nucleosynthesis process occurs. In this process, the abundance distribution of heavy-nuclei of achieve quasi-statistical equilibrium (QSE) at high temperature and the abundances are frozen at the end of the nucleosynthesis. We explain this abundance distribution using the "alpha-constrained QSE" abundances formulated in this paper. We demonstrate that this nucleosynthesis would occur in neutrino-driven winds from massive proto-neutron stars in hypernovae, where -nuclei are synthesized.
[Submitted on 13 Jan 2016] (cross-list from astro-ph.HE)
Hector O. Silva🇺🇸 · Hajime Sotani🇯🇵 · Emanuele Berti🇵🇹
The lowest neutron star masses currently measured are in the range , but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass by Martinez et al [Astrophys. J. 812, 143 (2015)] in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al [PTEP 2014, 051E01 (2014)] recently found empirical formulas relating the mass and surface redshift of nonrotating neutron stars to the star's central density and to the parameter , where is the incompressibility of symmetric nuclear matter and is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of and of the central density. These fits may be used to constrain , either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitational-wave spectrum.
[Submitted on 14 Jan 2016] (cross-list from hep-ph)
D. Gelfand🇩🇪 · F. Hebenstreit🇨🇭 · J. Berges🇩🇪
We perform real-time lattice simulations of out-of-equilibrium quark production in non-Abelian gauge theory in 3+1-dimensions. Our simulations include the backreaction of quarks onto the dynamical gluon sector, which is particularly relevant for strongly correlated quarks. We observe fast isotropization and universal behavior of quarks and gluons at weak coupling and establish a quantitative connection to previous pure glue results. In order to understand the strongly correlated regime, we perform simulations for a large number of flavors and compare them to those obtained with two light quark flavors. By doing this we are able to provide estimates of the chemical equilibration time.
[Submitted on 14 Jan 2016] (cross-list from nucl-ex)
There is much speculation and a modest amount of evidence that certain mesons might form quasi-bound states with nuclei to produce really exotic states of matter. For this to be a practical possibility, the interaction between the meson and nucleons at low energies must be strong and attractive and the production rates "healthy". The conditions for this are surveyed for the light mesons. How this might lead to quasi-bound states is then discussed in a few typical cases.
[Submitted on 14 Jan 2016] (cross-list from hep-ph)
Miguel A. Escobedo🇫🇷 · Edmond Iancu🇫🇷
We develop the event-by-event picture of the gluon distribution produced via medium-induced gluon branching by an energetic jet which propagates through a dense QCD medium. A typical event is characterized by the production of a large number of soft gluons which propagate at large angles with respect to the jet axis and which collectively carry a substantial amount of energy. By explicitly computing 2-gluon correlations, we demonstrate the existence of large event-by-event fluctuations, which reflect the stochastic nature of the branching process. For the two quantities that we have investigated -- the energy loss at large angles and the soft gluon multiplicity --, the dispersion is parametrically as large as the respective expectation value. We identify interesting scaling laws, which suggest that the multiplicity distribution should exhibit KNO (Koba-Nielsen-Olesen) scaling. A similar scaling is known to hold for a jet branching in the vacuum, but the medium-induced distribution is found to be considerably broader. We predict that event-by-event measurements of the di-jet asymmetry in Pb+Pb collisions at the LHC should observe large fluctuations in the number of soft hadrons propagating at large angles and also in the total energy carried by these hadrons.
first authorsco-authorsvia INSPIRE