Nuclear Theory·nucl-th

Friday·February 5, 2016

14 papers—7 primary·7 cross-listed

08
Comment on "Breakdown of the expansion of finite-size corrections to the hydrogen Lamb shift in moments of charge distribution"
J. Arrington🇺🇸
In a recent paper, Hagelstein and Pascalutsa examine the error associated with an expansion of proton structure corrections to the Lamb shift in terms of moments of the charge distribution. They propose a small modification to a conventional parameterization of the proton's charge form factor and show that this can resolve the proton radius puzzle. However, while the size of the "bump" they add to the form factor is small, it is large compared to the total proton structure effects in the initial parameterization, yielding a final form factor that is unphysical. Reducing their modification to the point where the resulting form factor is physical does not allow for a resolution of the radius puzzle.
↳ hep-phnucl-thphysics.atom-phPRA(2016)·3 citations
09
Reactor antineutrino fluxes - status and challenges
Patrick Huber🇺🇸
In this contribution we describe the current understanding of reactor antineutrino fluxes and point out some recent developments. This is not intended to be a complete review of this vast topic but merely a selection of observations and remarks, which despite their incompleteness, will highlight the status and the challenges of this field.
↳ hep-phnucl-thphysics.ins-detNPB(2016)·51 citations
10
Energetic emissions from deconfinement in compact stars and their relation to the critical end point in the QCD phase diagram
D. E. Alvarez-Castillo🇷🇺
In this work we study the case of deconfinement in compact star interiors in the presence of a strong first order phase transition associated to a critical end point in the QCD phase diagram. Neutron stars fulfilling these conditions show a third branch in the mass-radius diagram with the first and second branches being the white dwarfs and neutron stars configurations. The transition to the third branch can be reached by a pure hadronic neutron star through an induced collapse releasing energy that corresponds to a mass-energy difference between the second and third branch configurations. Physical outcomes of this phenomenon that can potentially explain the already detected astrophysical signals are discussed. In particular we present energy estimations for the case of a fast radio burst, seen as a double-peak structure in the object's light curve.
↳ astro-ph.HEhep-phnucl-thPublishing house Sneg, Pyatigorsk (2016) …·0 citations
11
A Hydrodynamic Approach to the Study of Anisotropic Instabilities in Dissipative Relativistic Plasmas
Esteban Calzetta🇦🇷 · Alejandra Kandus🇧🇷
We develop a purely hydrodynamic formalism to describe collisional, anisotropic instabilities in a relativistic plasma, that are usually described with kinetic theory tools. Our main motivation is the fact that coarse-grained models of high particle number systems give more clear and comprehensive physical descriptions of those systems than purely kinetic approaches, and can be more easily tested experimentally as well as numerically. In particular, we aim at developing a theory that describes both a background non-equilibrium fluid configurations and its perturbations, to be able to account for the backreaction of the latter on the former. Our system of equations includes the usual conservation laws for the energy-momentum tensor and for the electric current, and the equations for two new tensors that encode the information about dissipation. To make contact with kinetic theory, we write the different tensors as the moments of a non-equilibrium one-particle distribution function (1pdf) which, for illustrative purposes, we take in the form of a Grad-like ansatz. Although this choice limits the applicability of the formalism to states not far from equilibrium, it retains the main features of the underlying kinetic theory. We assume the validity of the Vlasov-Boltzmann equation, with a collision integral given by the Anderson-Witting prescription, which is more suitable for highly relativistic systems than Marle's (or Bhatnagar, Gross and Krook) form, and derive the conservation laws by taking its corresponding moments. We apply our developments to study the emergence of instabilities in an anisotropic, but axially symmetric background. For small departures of isotropy we find the dispersion relation for normal modes, which admit unstable solutions for a wide range of values of the parameter space.
↳ hep-phnucl-thphysics.flu-dynInt.J.Mod.Phys.A(2016)·8 citations
12
Speed of Sound in Hadronic matter using Non-extensive Tsallis Statistics
Arvind Khuntia🇮🇳 · Pragati Sahoo🇮🇳 · Prakhar Garg🇮🇳 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦
The speed of sound ( $c_{s}$ ) is studied to understand the hydrodynamical evolution of the matter created in heavy-ion collisions. The quark-gluon plasma (QGP) formed in heavy-ion collisions evolves from an initial QGP to the hadronic phase via a possible mixed phase. Due to the system expansion in a first order phase transition scenario, the speed of sound reduces to zero as the specific heat diverges. We study the speed of sound for systems, which deviate from a thermalized Boltzmann distribution using non-extensive Tsallis statistics. In the present work, we calculate the speed of sound as a function of temperature for different $q$ -values for a hadron resonance gas. We observe a similar mass cut-off behaviour in non-extensive case for $c_{s}^{2}$ by including heavier particles, as is observed in the case of a hadron resonance gas following equilibrium statistics. Also, we explicitly present that the temperature where the mass cut-off starts, varies with the $q$ -parameter which hints at a relation between the degree of non-equilibrium and the limiting temperature of the system. It is shown that for values of $q$ above approximately 1.13 all criticality disappear in the speed of sound, i.e. the decrease in the value of the speed of sound, observed at lower values of $q$ , disappears completely.
↳ hep-phnucl-exnucl-thEPJA(2016)·28 citations
13
Thermal Charm and Charmonium Production in Quark Gluon Plasma
Kai Zhou🇨🇳 · Zhengyu Chen🇨🇳 · Carsten Greiner🇩🇪 · Pengfei Zhuang🇨🇳
We study the effect of thermal charm production on charmonium regeneration in high energy nuclear collisions. By solving the kinetic equations for charm quark and charmonium distributions in Pb+Pb collisions, we calculate the global and differential nuclear modification factors $R_{AA} (N_{p a r t})$ and $R AA (p_{t})$ for $J /Ψ$ s. Due to the thermal charm production in hot medium, the charmonium production source changes from the initially created charm quarks at SPS, RHIC and LHC to the thermally produced charm quarks at Future Circular Collider (FCC), and the $J /Ψ$ suppression ( $R_{AA} < 1$ ) observed so far will be replaced by a strong enhancement ( $R_{AA} > 1$ ) at FCC at low transverse momentum.
↳ hep-phnucl-exnucl-thPLB(2016)·33 citations
14
Revealing transversity GPDs through the photoproduction of a photon and a $ρ$ meson
R. Boussarie🇫🇷 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · S. Wallon🇫🇷
Photoproduction of a pair of particles with large invariant mass is a natural extension of collinear QCD factorization theorems which have been much studied for deeply virtual Compton scattering and deeply virtual meson production. We discuss the production of a photon and a meson, where the wide angle Compton scattering on a meson subprocess factorizes from generalized parton distribution. We calculate at dominant twist and leading order in $α_{s}$ , the production cross-section of a transversely polarized $ρ$ meson which is sensitive to chiral-odd GPDs, and show that it may be measurable in near future JLab experiments.
↳ hep-phhep-exnucl-exnucl-thEPJ Web Conf.(2016)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE

Comment on "Breakdown of the expansion of finite-size corrections to the hydrogen Lamb shift in moments of charge distribution"

Reactor antineutrino fluxes - status and challenges

Energetic emissions from deconfinement in compact stars and their relation to the critical end point in the QCD phase diagram

A Hydrodynamic Approach to the Study of Anisotropic Instabilities in Dissipative Relativistic Plasmas

Speed of Sound in Hadronic matter using Non-extensive Tsallis Statistics

Thermal Charm and Charmonium Production in Quark Gluon Plasma

Revealing transversity GPDs through the photoproduction of a photon and a ρ meson

Affiliations

Revealing transversity GPDs through the photoproduction of a photon and a $ρ$ meson