Nuclear Theory·nucl-th

Wednesday·August 30, 2023

13 papers—4 primary·9 cross-listed

05
Basic characteristics of neutrino flavor conversions in the post-shock regions of core-collapse supernova
Hiroki Nagakura🇯🇵 · Masamichi Zaizen🇯🇵
One of the active debates in core-collapse supernova (CCSN) theory is how significantly neutrino flavor conversions induced by neutrino-neutrino self-interactions change the conventional picture of CCSN dynamics. Recent studies have indicated that strong flavor conversions can occur inside neutrino spheres where neutrinos are tightly coupled to matter. These flavor conversions are associated with either collisional instability or fast neutrino-flavor conversion (FFC) or both. The impact of these flavor conversions on CCSN dynamics is, however, still highly uncertain due to the lack of global simulations of quantum kinetic neutrino transport with appropriate microphysical inputs. Given fluid profiles from a recent CCSN model at three different time snapshots in the early post-bounce phase, we perform global quantum kinetic simulations in spherical symmetry with an essential set of microphysics. We find that strong flavor conversions occur in optically thick regions, resulting in a substantial change of neutrino radiation field. The neutrino heating in the gain region is smaller than the case with no flavor conversions, whereas the neutrino cooling in the optically thick region is commonly enhanced. Based on the neutrino data obtained from our multi-angle neutrino transport simulations, we also assess some representative classical closure relations by applying them to diagonal components of density matrix of neutrinos. We find that Eddington tensors can be well approximated by these closure relations except for the region where flavor conversions occur vividly. We also analyze the neutrino signal by carrying out detector simulations for Super-Kamiokande, DUNE, and JUNO. We propose a useful strategy to identify the sign of flavor conversions in neutrino signal, that can be easily implemented in real data analyses of CCSN neutrinos.
↳ astro-ph.HEhep-phnucl-thPRD(2023)·45 citations
06
Spacetime dynamics of chiral magnetic currents in a hot non-Abelian plasma
Sebastian Grieninger🇺🇸 · Dmitri E. Kharzeev🇺🇸
The correlations of electric currents in hot non-Abelian plasma are responsible for the experimental manifestations of the chiral magnetic effect (CME) in heavy-ion collisions. We evaluate these correlations using holography, and show that they are driven by large-scale topological fluctuations. In a non-Abelian plasma with chiral fermions, local axial charge can be generated either by topological fluctuations (creating domains with nonzero Chern-Simons number) or by thermal fluctuations. Within holography, we investigate the dynamical creation of the axial charge and isolate the imprint of the topological dynamics on the spatial correlations of electric current. In particular, we show that the spatial extent of the current correlation is quite large ( $\sim 1 fm$ ) and grows with time, which is consistent with sphaleronlike dynamics. We provide numerical estimates for this spatial size that can be used as an input in phenomenological analyses.
↳ hep-phhep-thnucl-thPRD(2023)·8 citations
07
Real-time dynamics of axial charge and chiral magnetic current in a non-Abelian expanding plasma
Sebastian Grieninger🇺🇸 · Sergio Morales-Tejera🇪🇸
Understanding axial charge dynamics driven by changes in Chern-Simons number densities is a key aspect in understanding the chiral magnetic effect (CME) in heavy-ion collisions. Most phenomenological simulations assume that a large amount of axial charge is produced in the initial stages and that axial charge is conserved throughout the simulation. Within an (expanding) homogeneous holographic plasma, we investigate the real-time axial charge relaxation dynamics and their impact on the chiral magnetic current. Moreover, we discuss the real-time interplay of the non-Abelian and the Abelian chiral anomaly in the presence of a strong magnetic field. In the expanding plasma, the Chern-Simons diffusion rate and thus the axial charge relaxation rate are time dependent due to the decaying magnetic field. We quantify the changes in the late time falloffs and establish a horizon formula for the chiral magnetic current.
↳ hep-phhep-thnucl-thPRD(2023)·10 citations
08
QCMATH: Mathematica modules for electronic structure calculations
Enzo Monino · Antoine Marie · Pierre-François Loos
We introduce \textsc{qcmath}, a user-friendly quantum chemistry software tailored for electronic structure calculations, implemented using the Wolfram Mathematica language and available at \url{https://github.com/LCPQ/qcmath}. This software, designed with accessibility in mind, takes advantage of the symbolic capabilities intrinsic to Mathematica. Its primary goal is to provide a supportive environment for newcomers to the field of quantum chemistry, enabling them to easily conceptualize, develop, and test their own ideas. The functionalities of \textsc{qcmath} encompass a broad spectrum of methods, catering to both ground- and excited-state calculations. We provide a comprehensive overview of these capabilities, complemented by essential theoretical insights. To facilitate ease of use, we offer an exhaustive blueprint of the software's architecture. Furthermore, we provide users with comprehensive guides, addressing both the operational aspects and the more intricate programming facets of \textsc{qcmath}.
↳ physics.chem-phcond-mat.str-elnucl-thphysics.comp-ph0 citations
09
Note on the electromagnetic radius of proton
M. Ridwan🇮🇩 · T. Mart🇮🇩
We have analyzed the proton form factor data by using a number of phenomenological parameterizations (models) and extracting the proton electric and magnetic radii. To this end we performed a global fit to all available form factor data, with the virtual photon momentum squared $Q^{2}$ from $0.0002$ to nearly 10 GeV $^{2}$ for electric form factor and from $0.015$ to 31 GeV $^{2}$ for magnetic one. Special attention was given to the small structure shown by the form factor data near $Q^{2} = 0.2$ GeV $^{2}$ . It was found that different models yield different structures with different numbers of minimum at this kinematics. Since the slope of form factor in the limit of $Q^{2} \to 0$ is influenced by this structure, the extracted proton radii are consequently different for different models. Our finding recommends that future experiments should focus on this kinematics instead of low $Q^{2}$ . Experimental data with accuracies comparable to those of the latest data at low $Q^{2}$ would clearly help to clarify the effect of this structure on the proton charge radius. Interestingly, most of the extracted proton charge radii were found to be closer to the value obtained from the muonic hydrogen atom spectroscopy.
↳ hep-phnucl-exnucl-thphysics.pop-phMod.Phys.Lett.A(2023)·4 citations
10
$J / ψ$ and $ψ$ (2S) polarization in proton-proton collisions at energies available at the CERN Large Hadron Collider using PYTHIA8
Bhagyarathi Sahoo🇮🇳 · Dushmanta Sahu🇮🇳 · Suman Deb🇫🇷 · Captain R. Singh🇮🇳 · Raghunath Sahoo🇮🇳
The production mechanisms of charmonium states in both hadronic and heavy-ion collisions hold great significance for investigating the hot and dense QCD matter. Studying charmonium polarization in ultra-relativistic collisions can also provide insights into the underlying production mechanisms. With this motivation, we explore the $J / ψ$ and $ψ$ (2S) polarization in proton+proton collisions at $s$ = 7, 8, and 13 TeV using a pQCD-inspired Monte-Carlo event generator called PYTHIA8. This work considers reconstructed quarkonia through their dimuons decay channel in the ALICE forward rapidity acceptance range of $2.5 < y_{μμ} < 4$ . Further, we calculate the polarization parameters $λ_{θ}$ , $λ_{ϕ}$ , $λ_{θ ϕ}$ from the polar and azimuthal angular distributions of the dimuons in helicity and Collins-Soper frames. This study presents a comprehensive measurement of the polarization parameters as a function of transverse momentum, charged-particle multiplicity, and rapidity at the LHC energies. Our findings of charmonium polarization are in qualitative agreement with the corresponding experimental data.
↳ hep-phhep-exnucl-exnucl-thPRC(2024)·16 citations
11
Simulation of 3+1D glasma in Milne coordinates I: Development of the framework
Hidefumi Matsuda🇨🇳 · Xu-Guang Huang🇨🇳
We propose a new numerical method for $3 + 1$ D glasma simulation using Milne coordinates. We formulate the classical Yang-Mills field and $3$ D classical color current on a lattice at the initial proper time, specified as a moment just before the collision of the two nuclei. By solving the evolution equations, we extract observables of the $3$ D glasma at later times. We demonstrate the efficiency of our method in terms of numerical cost and apply it to the central collisions of Au-Au. We also discuss possible further improvements of our method.
↳ hep-phnucl-thPRD(2023)·12 citations
12
Bayesian Survey of the Dense Matter Equation of State built upon Skyrme effective interactions
Mikhail V. Beznogov🇷🇴 · Adriana R. Raduta🇷🇴
The non-relativistic model of nuclear matter with zero-range Skyrme interactions is employed within a Bayesian approach in order to study the behavior of neutron stars (NSs) equation of state (EOS). A minimal number of constraints from nuclear physics and ab initio calculations of pure neutron matter (PNM) are imposed together with causality and a lower limit on the maximum mass of NS to all our models. Our key result is that accounting for correlations among the values that the energy per neutron in PNM takes at various densities, and that are typically disregarded, efficiently constrains the behavior of the EOS at high densities. A series of global NS properties, e.g., maximum mass, central density of the maximum mass configuration, minimum NS mass that allows for direct URCA, radii of intermediate and massive NS, appear to be correlated with the value of effective neutron mass in PNM at 0.16 fm $^{- 3}$ . Together with similar studies in the literature our work contributes to a better understanding of the NS EOS as well as its link with the properties of dense nuclear matter.
↳ astro-ph.HEnucl-thApJ(2024)·16 citations
13
Unraveling anomalies in Deeply Virtual Compton Scattering
Shohini Bhattacharya🇺🇸 · Yoshitaka Hatta🇺🇸 · Werner Vogelsang🇩🇪
We calculate the one-loop quark box diagrams relevant to polarized and unpolarized Deeply Virtual Compton Scattering by introducing an off-forward momentum $l^{μ}$ as an infrared regulator. This regularization approach allows us to reveal the poles associated with the chiral anomaly in the polarized scenario, as well as the trace anomaly in the unpolarized case. We provide an interpretation of our findings in the context of pertinent Generalized Parton Distributions (GPDs). Furthermore, we discuss the implications of these poles on the QCD factorization pertaining to Compton amplitudes.
↳ hep-phnucl-th2 citations

Affiliations

first authorsco-authorsvia INSPIRE