Nuclear Theory·nucl-th

Wednesday·March 20, 2019

13 papers—7 primary·6 cross-listed

01
[Submitted on 18 Mar 2019]
The JETSCAPE framework
J. H. Putschke🇺🇸 · K. Kauder🇺🇸 · E. Khalaj🇺🇸 · A. Angerami🇺🇸 · S. A. Bass🇺🇸 · S. Cao🇺🇸 · J. Coleman🇺🇸 · L. Cunqueiro🇺🇸 · T. Dai🇺🇸 · L. Du🇺🇸 · H. Elfner🇩🇪 · D. Everett🇺🇸 and 33 other authors
The JETSCAPE simulation framework is an overarching computational envelope for developing complete event generators for heavy-ion collisions. It allows for modular incorporation of a wide variety of existing and future software that simulates different aspects of a heavy-ion collision. The default JETSCAPE package contains both the framework, and an entire set of indigenous and third party routines that can be used to directly compare with experimental data. In this article, we outline the algorithmic design of the JETSCAPE framework, define the interfaces and describe the default modules required to carry out full simulations of heavy-ion collisions within this package. We begin with a description of the various physics elements required to simulate an entire event in a heavy-ion collision, and distribute these within a flowchart representing the event generator and statistical routines for comparison with data. This is followed by a description of the abstract class structure, with associated members and functions required for this flowchart to work. We then define the interface that will be required for external users of JETSCAPE to incorporate their code within this framework and to modify existing elements within the default distribution. We conclude with a discussion of some of the physics output for both $p$ - $p$ and $A$ - $A$ collisions from the default distribution, and an outlook towards future releases. In the appendix, we discuss various architectures on which this code can be run and outline our benchmarks on similar hardware.
Comments:
93 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1903.07706 [pdf]
191 citations
02
[Submitted on 18 Mar 2019]
Forbidden transitions in neutral and charged current interactions between low-energy neutrinos and Argon
Nils Van Dessel🇧🇪 · Natalie Jachowicz🇧🇪 · Alexis Nikolakopoulos🇧🇪
Background: The study of low-energy neutrinos and their interactions with atomic nuclei is crucial to several open problems in physics, including the neutrino mass hierarchy, CP-violation, candidates of Beyond Standard Model physics and supernova dynamics. Examples of experiments include CAPTAIN at SNS as well as DUNE's planned detection program of supernova neutrinos. Purpose: We present cross section calculations for quasielastic charged current and neutral current neutrinos at low energies, with a focus on $^{40}$ Ar. We also take a close look at pion decay-at-rest neutrino spectra, which are used in e.g. the SNS experiment at Oakridge. Method and results: We employ a Hartree Fock + Continuum Random Phase Approximations (HF+CRPA) framework, which allows us to model the responses and include the effects of long-range correlations. It is expected to provide a good framework to calculate forbidden transitions, whose contribution which we show to be non-negligible. Conclusions: Forbidden transitions can be expected to contribute sizeably to the reaction strength at typical low-energy kinematics, such as DAR neutrinos. Modeling and Monte Carlo simulations need to take all due care to account for the influence of their contributions.
Comments:
11 pages, 16 figures; minor corrections to v2
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.07726 [pdf]
PRC(2019)·19 citations
03
[Submitted on 19 Mar 2019]
A Pattern for the Flavor Dependence of the Quark-Gluon Interaction
Muyang Chen🇨🇳 · Lei Chang🇨🇳
A flavor dependent kernel is constructed based on the rainbow-ladder truncation of the Dyson-Schwinger and Bethe-Salpeter equation approach of Quantum Chromodynamics. The quark-antiquark interaction is composed of a flavor dependent infrared part and a flavor independent ultraviolet part. Our model gives a successful and unified description of the light, heavy and heavy-light ground pseudoscalar and vector mesons. For the first time, our model shows that the infrared enhanced quark-antiquark interaction is stronger and wider for the lighter quark.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1903.07808 [pdf]
CPC(2019)·29 citations
04
[Submitted on 19 Mar 2019]
Role of dynamic pairing correlations in fission dynamics
R. Bernard🇫🇷 · S.A. Giuliani🇺🇸 · L.M. Robledo🇪🇸
We study the role of dynamic pairing correlations in fission dynamics by considering intrinsic Hartree-Fock-Bogoliubov wave functions that are obtained by minimizing the particle number projected energy. For the restricted variational space, the set of self-consistent wave functions with different values of proton and neutron number particle fluctuations are considered. The particle number projected energy is used to define potential energy surface for fission whereas collective inertias are computed within the traditional formulas for the intrinsic states. The results show that the effect of the restricted variation after particle number projection in the potential energy surface is small while collective inertias substantially decrease. On the other hand, we show that this quenching is strongly mitigated when Coulomb antipairing is considered. In the light of these beyond mean-field calculations, the validity of traditional fission calculations is discussed.
Comments:
7 pages, 3 Figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.07892 [pdf]
PRC(2019)·23 citations
05
[Submitted on 19 Mar 2019]
Poincare' covariant light-front spectral function and transverse momentum distribution
Emanuele Pace · Giovanni Salme' · Sergio Scopetta
In valence approximation the fermion correlator is simply related to the light-front spectral function. Then the leading twist time-reversal even transverse momentum distributions can be explicitly obtained from the light-front wave function of the system and the twist-three distributions are linear combinations of the transverse distributions at leading twist.
Comments:
4 pages, talk given at the XXII International Conference on Few-Body Problems in Physics (FB22), Caen, France, July 9 - 13, 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1903.08073 [pdf]
0 citations
06
[Submitted on 19 Mar 2019]
Muon capture in nuclei: an ab initio approach based on quantum Monte Carlo methods
A. Lovato🇺🇸 · N. Rocco🇺🇸 · R. Schiavilla🇺🇸
An ab initio quantum Monte Carlo method is introduced for calculating total rates of muon weak capture in light nuclei with mass number $A \leq 12$ . As a first application of the method, we perform a calculation of the rate in $^{4}$ He in a dynamical framework based on realistic two- and three-nucleon interactions and realistic nuclear charge-changing weak currents. The currents include one- and two-body terms induced by $π$ - and $ρ$ -meson exchange, and $N$ -to- $Δ$ excitation, and are constrained to reproduce the empirical value of the Gamow-Teller matrix element in tritium. We investigate the sensitivity of theoretical predictions to current parametrizations of the nucleon axial and induced pseudoscalar form factors as well as to two-body contributions in the weak currents. The large uncertainties in the measured values obtained from bubble-chamber experiments (carried out over 50 years ago) prevent us from drawing any definite conclusions.
Comments:
6 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1903.08078 [pdf]
PRC(2019)·19 citations
07
[Submitted on 19 Mar 2019]
Particle-Set Identification method to study multiplicity fluctuations
M. Gazdzicki🇵🇱 · M. I. Gorenstein🇺🇦 · M. Mackowiak-Pawlowska🇵🇱 · A. Rustamov🇩🇪
In this paper a new method of experimental data analysis, the Particle-Set Identification method, is presented. The method allows to reconstruct moments of multiplicity distribution of identified particles. The difficulty the method copes with is due to incomplete particle identification -- a particle mass is frequently determined with a resolution which does not allow for a unique determination of the particle type. Within this method the moments of order $k$ are calculated from mean multiplicities of $k$ -particle sets of a given type. The Particle-Set Identification method remains valid even in the case of correlations between mass measurements for different particles. This distinguishes it from the Identity method introduced by us previously to solve the problem of incomplete particle identification in studies of particle fluctuations.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1903.08103 [pdf]
NPA(2020)·4 citations
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