Nuclear Theory·nucl-th

Friday·October 30, 2020

15 papers—8 primary·7 cross-listed

09
Non-thermal neutrinos created by shock acceleration in successful and failed core-collapse supernova
Hiroki Nagakura🇺🇸 · Kenta Hotokezaka🇯🇵
We present a comprehensive study of neutrino shock acceleration in core-collapse supernova (CCSN). The leading players are heavy leptonic neutrinos, $ν_{μ}$ and $ν_{τ}$ ; the former and latter potentially gain the energy up to $\sim 100$ MeV and $\sim 200$ MeV, respectively, through the shock acceleration. Demonstrating the neutrino shock acceleration by Monte Carlo neutrino transport, we make a statement that it commonly occurs in the early post bounce phase ( $≲ 50$ ms after bounce) for all massive stellar collapse experiencing nuclear bounce and would reoccur in the late phase ( $≳ 100$ ms) for failed CCSNe. This opens up a new possibility to detect high energy neutrinos by terrestrial detectors from Galactic CCSNe; hence, we estimate the event counts for Hyper(Super)-Kamiokande, DUNE, and JUNO. We find that the event count with the energy of $≳ 80$ MeV is a few orders of magnitude higher than that of the thermal neutrinos regardless of the detectors, and muon production may also happen in these detectors by $ν_{μ}$ with the energy of $≳ 100$ MeV. The neutrino signals provide a precious information on deciphering the inner dynamics of CCSN and placing a constraint on the physics of neutrino oscillation; indeed, the detection of the high energy neutrinos through charged current reaction channels will be a smoking gun evidence of neutrino flavor conversion.
↳ astro-ph.HEhep-exhep-phnucl-ex+1MNRAS(2021)·17 citations
10
Astromers: Nuclear Isomers in Astrophysics
G. Wendell Misch · Surja K. Ghorui · Projjwal Banerjee · Yang Sun · Matthew R. Mumpower
We develop a method to compute thermally-mediated transition rates between the ground state and long-lived isomers in nuclei. We also establish criteria delimiting a thermalization temperature above which a nucleus may be considered a single species and below which it must be treated as two separate species: a ground state species, and an astrophysical isomer ("astromer") species. Below the thermalization temperature, the destruction rates dominate the internal transition rates between the ground state and the isomer. If the destruction rates also differ greatly from one another, the nuclear levels fall out of or fail to reach thermal equilibrium. Without thermal equilibrium, there may not be a safe assumption about the distribution of occupation probability among the nuclear levels when computing nuclear reaction rates. In these conditions, the isomer has astrophysical consequences and should be treated a separate astromer species which evolves separately from the ground state in a nucleosynthesis network. We apply our transition rate methods and perform sensitivity studies on a few well-known astromers. We also study transitions in several other isomers of likely astrophysical interest.
↳ astro-ph.HEnucl-thAstrophys.J.Suppl.(2021)·60 citations
11
Higher order cumulants of electric charge and strangeness fluctuations on the crossover line
D. Bollweg🇩🇪 · J. Goswami🇩🇪 · F. Karsch🇩🇪 · S. Mukherjee🇺🇸 · C. Schmidt🇩🇪
We present lattice QCD calculations of higher order cumulants of electric charge distributions for small baryon chemical potentials $μ_{B}$ by using up to NNNLO Taylor expansions. Ratios of these cumulants are evaluated on the pseudo-critical line, $T_{p c} (μ_{B})$ , of the chiral transition and compared to corresponding measurements in heavy ion collision experiments by the STAR and PHENIX Collaborations. We demonstrate that these comparisons give strong constraints on freeze-out parameters. Furthermore, we use strangeness fluctuation observables to compute the ratio $μ_{S} / μ_{B}$ on the crossover line and compare it to $μ_{S} / μ_{B}$ at freeze-out stemming from fits to strange baryon yields measured by the STAR Collaboration.
↳ hep-lathep-phnucl-thActa Phys.Polon.B(2021)·3 citations
12
How do I introduce Schrödinger equation during the quantum mechanics course?
T. Mart🇮🇩
In this paper I explain how I usually introduce the Schrödinger equation during the quantum mechanics course. My preferred method is the chronological one. Since the Schrödinger equation belongs to a special case of wave equations I start the course with introducing the wave equation. The Schrödinger equation is derived with the help of the two quantum concepts introduced by Max Planck, Einstein, and de Broglie, i.e., the energy of a photon $E = ℏ ω$ and the wavelength of the de Broglie wave $λ = h / p$ . Finally, the difference between the classical wave equation and the quantum Schrödinger one is explained in order to help the students to grasp the meaning of quantum wavefunction $Ψ (r, t)$ . A comparison of the present method to the approaches given by the authors of quantum mechanics textbooks as well as that of the original Nuffield A level is presented. It is found that the present approach is different from those given by these authors, except by Weinberg or Dicke and Wittke. However, the approach is in line with the original Nuffield A level one.
↳ physics.ed-phhep-phnucl-thquant-phPhys.Educ.(2021)·1 citation
13
Universal scaling properties of QCD close to the chiral limit
Olaf Kaczmarek🇩🇪 · Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Christian Schmidt🇩🇪
We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two massless (up and down) and one strange quark having its physical mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light quark masses, corresponding to Goldstone pion masses in the range of $58 MeV ≲ m_{π} ≲ 163 MeV$ . The chiral phase transition temperature is determined by extrapolating to vanishing pion mass using universal scaling relations. After thermodynamic, continuum and chiral extrapolations we find the chiral phase transition temperature $T_{c}^{0} = 13 2_{- 6}^{+ 3}$ MeV. We also show some preliminary calculations that use the conventional estimator for the pseudo-critical temperature and compare with the new estimators for $T_{c}^{0}$ . Furthermore, we show results for the ratio of the chiral order parameter and its susceptibility and argue that this ratio can be used to differentiate between $O (N)$ and $Z_{2}$ universality classes in a non-parametric manner.
↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·9 citations
14
Independent Normalization for $γ$ -ray Strength Functions: The Shape Method
M. Wiedeking · M. Guttormsen · A.C. Larsen · F. Zeiser · A. Görgen · S. N. Liddick · D. Mücher · S. Siem · A. Spyrou
The Shape method, a novel approach to obtain the functional form of the $γ$ -ray strength function ( $γ$ SF) in the absence of neutron resonance spacing data, is introduced. When used in connection with the Oslo method the slope of the Nuclear Level Density (NLD) is obtained simultaneously. The foundation of the Shape method lies in the primary $γ$ -ray transitions which preserve information on the functional form of the $γ$ SF. The Shape method has been applied to $^{56}$ Fe, $^{92}$ Zr, $^{164}$ Dy, and $^{240}$ Pu, which are representative cases for the variety of situations encountered in typical NLD and $γ$ SF studies. The comparisons of results from the Shape method to those from the Oslo method demonstrate that the functional form of the $γ$ SF is retained regardless of nuclear structure details or $J^{π}$ values of the states fed by the primary transitions.
↳ physics.data-annucl-exnucl-thPRC(2021)·38 citations
15
Sensitivity of the Polyakov loop to chiral symmetry restoration
David Anthony Clarke🇩🇪 · Olaf Kaczmarek🇩🇪 · Anirban Lahiri🇩🇪 · Mugdha Sarkar🇩🇪
In the heavy, static quark mass regime of QCD, the Polyakov loop is well known to be an order parameter of the deconfinement phase transition; however, the sensitivity of the Polyakov loop to the deconfinement of light, dynamical quarks is less clear. On the other hand, from the perspective of an effective Lagrangian written in the vicinity of the chiral transition, the Polyakov loop is an energy-like operator and should hence scale as any energy-like operator would. We show here that the Polyakov loop and heavy-quark free energy are sensitive to the chiral transition, i.e. their scaling is consistent with energy-like observables in 3- $d$ $O (N)$ universality classes.
↳ hep-lathep-phnucl-thActa Phys.Polon.Supp.(2021)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Non-thermal neutrinos created by shock acceleration in successful and failed core-collapse supernova

Astromers: Nuclear Isomers in Astrophysics

Higher order cumulants of electric charge and strangeness fluctuations on the crossover line

How do I introduce Schrödinger equation during the quantum mechanics course?

Universal scaling properties of QCD close to the chiral limit

Independent Normalization for γ-ray Strength Functions: The Shape Method

Sensitivity of the Polyakov loop to chiral symmetry restoration

Affiliations

Independent Normalization for $γ$ -ray Strength Functions: The Shape Method