Nuclear Theory·nucl-th

Wednesday·March 20, 2019

13 papers—7 primary·6 cross-listed

08
[Submitted on 18 Mar 2019] (cross-list from nucl-ex)
Open Heavy-Flavor Production in Heavy-Ion Collisions
Xin Dong🇺🇸 · Yen-jie Lee🇺🇸 · Ralf Rapp🇺🇸
The ultra-relativistic heavy-ion programs at the Relativistic Heavy Ion Collider and the Large Hadron Collider have evolved into a phase of quantitative studies of Quantum Chromodynamics at very high temperatures. The charm and bottom hadron production offer unique insights into the remarkable transport properties and the microscopic structure of the Quark-Gluon Plasma (QGP) created in these collisions. Heavy quarks, due to their large masses, undergo Brownian motion at low momentum, provide a window on hadronization mechanisms at intermediate momenta, and are expected to merge into a radiative-energy loss regime at high momentum. We review recent experimental and theoretical achievements on measuring a variety of heavy-flavor observables, characterizing the different regimes in momentum, extracting pertinent transport coefficients and deducing implications for the "inner workings" of the QGP medium.
Comments:
28 pages, 8 figures, submitted to Annu. Rev. of Nucl. and Part. Sci
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1903.07709 [pdf]
Ann.Rev.Nucl.Part.Sci.(2019)·179 citations
09
[Submitted on 19 Mar 2019] (cross-list from gr-qc)
Thermodynamics conditions of matter in neutron star mergers
Albino Perego · Sebastiano Bernuzzi · David Radice
Matter in neutron star collisions can reach densities up to few times the nuclear saturation threshold and temperatures up to one hundred MeV. Understanding the structure and composition of such matter requires many-body nonperturbative calculations that are currently highly uncertain.Unique constraints on the neutron star matter are provided by gravitational-wave observations aided by numerical relativity simulations. In this work, we explore the thermodynamical conditions of matter and radiation along the merger dynamics. We consider 3 microphysical equation of state models and numerical relativity simulations including an approximate neutrino transport scheme. The neutron star cores collision and their multiple centrifugal bounces heat the initially cold matter to several tens of MeV. Streams of hot matter with initial densities $\sim 1 - 2 ρ_{0}$ move outwards and cool due to decompression and neutrino emission. The merger can result in a neutron star remnant with densities up to $3 - 5 ρ_{0}$ and temperatures $\sim 50$ ~MeV. The highest temperatures are confined in an approximately spherical annulus at densities $\sim ρ_{0}$ . Such temperatures favour positron-neutron capture at densities $\sim ρ_{0}$ , thus leading to a neutrino emission dominated by electron antineutrinos. We study the impact of trapped neutrinos on the remnant matter's pressure, electron fraction and temperature and find that it has a negligible effect. Disks around neutron star or black hole remnant are neutron rich and not isentropic, but they differ in size, entropy and lepton fraction depending on the nature of the central object. In presence of a black hole, disks are smaller and mostly transparent to neutrinos; in presence of a massive neutron star, they are more massive, geometrically and optically thick.
Comments:
23 pages, 10 Figures, to be submitted to EPJA Topical Issue: The first Neutron Star Merger Observation - Implications for Nuclear Physics. Movies of the thermodynamical conditions available also on the youtube channel https://www.youtube.com/channel/UChmn-JGNa9mfY5H5938jnig
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1903.07898 [pdf]
EPJA(2019)·206 citations
10
[Submitted on 19 Mar 2019] (cross-list from hep-ph)
Proton scalar dipole polarizabilities from real Compton scattering data, using fixed-t subtracted dispersion relations and the bootstrap method
B. Pasquini (Pavia U. & INFN, Pavia)🇮🇹 · P. Pedroni (INFN, Pavia)🇮🇹 · S. Sconfietti (Pavia U. & INFN, Pavia)🇮🇹
We perform a fit of the real Compton scattering (RCS) data below pion-production threshold to extract the electric ( $α_{E 1}$ ) and magnetic ( $β_{M 1}$ ) static scalar dipole polarizabilities of the proton, using fixed- $t$ subtracted dispersion relations and a bootstrap-based fitting technique. The bootstrap method provides a convenient tool to include the effects of the systematic errors on the best values of $α_{E 1}$ and $β_{M 1}$ and to propagate the statistical errors of the model parameters fixed by other measurements. We also implement various statistical tests to investigate the consistency of the available RCS data sets below pion-production threshold and we conclude that there are not strong motivations to exclude any data point from the global set. Our analysis yields $α_{E 1} = (12.0 3_{- 0.54}^{+ 0.48}) \times 1 0^{- 4} fm^{3}$ and $β_{M 1} = (1.7 7_{- 0.54}^{+ 0.52}) \times 1 0^{- 4} fm^{3}$ , with p-value $= 12%$ .
Comments:
19 pages, 11 figures, 4 tables; final version accepted for publication in J. Phys. G
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1903.07952 [pdf]
J.Phys.G(2019)·29 citations
11
[Submitted on 19 Mar 2019] (cross-list from hep-ph)
Toward a First-Principles Calculation of Electroweak Box Diagrams
Chien-Yeah Seng🇩🇪 · Ulf-G. Meißner🇩🇪
We derive a Feynman-Hellmann theorem relating the second-order nucleon energy shift resulting from the introduction of periodic source terms of electromagnetic and isovector axial currents to the parity-odd nucleon structure function $F_{3}^{N}$ . It is a crucial ingredient in the theoretical study of the $γ W$ and $γ Z$ box diagrams that are known to suffer from large hadronic uncertainties. We demonstrate that for a given $Q^{2}$ , one only needs to compute a small number of energy shifts in order to obtain the required inputs for the box diagrams. Future lattice calculations based on this approach may shed new light on various topics in precision physics including the refined determination of the Cabibbo-Kobayashi-Maskawa matrix elements and the weak mixing angle.
Comments:
Version to appear in PRL
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:
1903.07969 [pdf]
PRL(2019)·36 citations
12
[Submitted on 19 Mar 2019] (cross-list from hep-ph)
Transport coefficients from in medium quarkonium dynamics
Nora Brambilla🇩🇪 · Miguel A. Escobedo🇪🇸 · Antonio Vairo🇩🇪 · Peter Vander Griend🇩🇪
The in medium dynamics of heavy particles are governed by transport coefficients. The heavy quark momentum diffusion coefficient, $κ$ , is an object of special interest in the literature, but one which has proven notoriously difficult to estimate, despite the fact that it has been computed by weak-coupling methods at next-to-leading order accuracy, and by lattice simulations of the pure SU(3) gauge theory. Another coefficient, $γ$ , has been recently identified. It can be understood as the dispersive counterpart of $κ$ . Little is known about $γ$ . Both $κ$ and $γ$ are, however, of foremost importance in heavy quarkonium physics as they entirely determine the in and out of equilibrium dynamics of quarkonium in a medium, if the evolution of the density matrix is Markovian, and the motion, quantum Brownian; the medium could be a strongly or weakly coupled plasma. In this paper, using the relation between $κ$ , $γ$ and the quarkonium in medium width and mass shift respectively, we evaluate the two coefficients from existing 2+1 flavor lattice QCD data. The resulting range for $κ$ is consistent with earlier determinations, the one for $γ$ is the first non-perturbative determination of this quantity.
Comments:
8 pages, 3 figures, journal version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1903.08063 [pdf]
PRD(2019)·77 citations
13
[Submitted on 19 Mar 2019] (cross-list from hep-ph)
Thermal Heavy Quark Self-Energy from Euclidean Correlators
Alexander M. Eller🇩🇪 · Jacopo Ghiglieri🇨🇭 · Guy D. Moore🇩🇪
Brambilla, Escobedo, Soto, and Vairo have derived an effective description of quarkonium with two parameters; a momentum diffusion term and a real self-energy term. We point out that there is a similar real self-energy term for a single open heavy flavor and that it can be expressed directly in terms of Euclidean electric field correlators along a Polyakov line. This quantity can be directly studied on the lattice without the need for analytical continuation. We show that Minkowski-space calculations of this correlator correspond with the known NLO Euclidean value of the relevant electric field two-point function and that it differs from the real self-energy term for quarkonium.
Comments:
5 pages, 1 figure. v2: very minor edits, matches journal version. v3: Eqs. (11) and (17) of v2 fixed, title and abstract modified, conclusions changed
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1903.08064 [pdf]
PRD(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Open Heavy-Flavor Production in Heavy-Ion Collisions

Thermodynamics conditions of matter in neutron star mergers

Proton scalar dipole polarizabilities from real Compton scattering data, using fixed-t subtracted dispersion relations and the bootstrap method

Toward a First-Principles Calculation of Electroweak Box Diagrams

Transport coefficients from in medium quarkonium dynamics

Thermal Heavy Quark Self-Energy from Euclidean Correlators

Affiliations