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Nuclear Theory·nucl-th

Friday·May 20, 2022

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    At the heart of baryonic matter the ARBUZ model favored by recent hadron form factor data

    Egle Tomasi-Gustafsson🇫🇷 · Simone Pacetti🇮🇹

    Data on electromagnetic form factors of proton, neutron, and from annihilation and scattering reactions are collected and interpreted in the frame of a generalized picture of the internal structure of baryons which holds in space-like and time-like regions. It is shown that these data give an insight of the space structure of the baryon for distances one hundred times smaller than the baryon size and, in the time-like region, a vision of the time evolution of the hadronic matter for times up to ~s, that is two orders of magnitude shorter than the time taken by the light to cross the volume of a proton. In the proposed interpretation, the electric form factor of the proton in the space-like region can not cross zero, but vanishes or stays very small, as an extrapolation of the data seems to show. In the time-like region specific structures appearing in the data give evidence of the dominance of the quark-diquark structure in a specific range of time of the evolution of the system.

    nucl-thhep-ph0 citations
  2. 02

    Nuclear Weak Rates and Nuclear Weak Processes in Stars

    Toshio Suzuki🇯🇵

    Nuclear weak rates in stellar environments are obtained by shell-model calculations including Gamow-Teller (GT) and spin-dipole transitions, and applied to nuclear weak processes in stars. The important roles of accurate weak rates for the study of astrophysical processes are pointed out. The weak rates in -shell are used to study the evolution of ONeMg cores in stars with 8-10 M. Cooling of the core by nuclear Urca processes, and the heating by double e-captures on Ne are studied. Especially, the e-capture rates for a second-forbidden transition in Ne are evaluated with the multipole expansion method of Walecka and Behrens-Bhring, and the final fate of the cores, core-collapse or thermonuclear explosion, are discussed. The weak rates in -shell are applied to nucleosynthesis of iron-group elements in Type Ia supernovae. The over-production problem of neutron-rich iron isotopes compared with the solar abundances is now reduced to be within a factor of two. The weak rates for nuclear Urca pair with =31 in the island of inversion are evaluated with the effective interaction obtained by the extended Kuo-Krenciglowa method. The transition strengths and e-capture rates in Ni, important for core-collapse processes, are evaluated with the - shell, and compared with those obtained by the random-phase-approximation and an effective rate formula. -decay rates of =126 isotones are evaluated with both the GT and first-forbidden transitions. The half-lives are found to be shorter than those obtained by standard models. Neutrino-nucleus reaction cross sections on C, O and Ar are obtained with new shell-model Hamiltonians. Implications on nucleosynthesis, neutrino detection, neutrino oscillations and neutrino mass hierarchy are discussed.

    nucl-thastro-ph.SRPPNP(2022)·18 citations
  3. 03

    Role of non-gaussian quantum fluctuations in neutrino entanglement

    Denis Lacroix🇫🇷 · A. B. Balantekin🇺🇸 · Michael J. Cervia🇺🇸 · Amol V. Patwardhan🇺🇸 · Pooja Siwach🇺🇸

    The flavor evolution of neutrinos in environments with large neutrino number densities is an open problem at the nexus of astrophysics and neutrino flavor physics. Among the many unanswered questions pertaining to this problem, it remains to be determined whether neutrino-neutrino coherent scattering can give rise to nontrivial quantum entanglement among neutrinos, and whether this can affect the flavor evolution in a meaningful way. To gain further insight into this question, here we study a simple system of two interacting neutrino beams, and obtain the exact phase-space explored by this system using the Husimi quasi-probability distribution. We observe that the entanglement induced by the coupling leads to strong delocalization in phase-space with largely non-Gaussian quantum fluctuations. The link between the neutrino entanglement and quantum fluctuations is illustrated using the one- and two-neutrino entropy. In addition, we propose an approximate phase-space method to describe the interacting neutrinos problem, where the exact evolution is replaced by a set of independent mean-field evolutions with a statistical sampling of the initial conditions. The phase-space approach provides a simple and accurate method to describe the gross features of the neutrino entanglement problem. Applications are shown using time-independent and time-dependent Hamiltonians in the non-adiabatic regime.

    nucl-thhep-phquant-phPRD(2022)·51 citations

Affiliations

first authorsco-authorsvia INSPIRE