Nuclear Theory·nucl-th

Friday·May 20, 2022

6 papers—3 primary·3 cross-listed

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 $Λ$ 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 $1 0^{- 25}$ ~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
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 $s d$ -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 $^{20}$ Ne are studied. Especially, the e-capture rates for a second-forbidden transition in $^{20}$ Ne are evaluated with the multipole expansion method of Walecka and Behrens-B $\mbox u ¨$ hring, and the final fate of the cores, core-collapse or thermonuclear explosion, are discussed. The weak rates in $p f$ -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 $A$ =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 $^{78}$ Ni, important for core-collapse processes, are evaluated with the $p f$ - $s d g$ shell, and compared with those obtained by the random-phase-approximation and an effective rate formula. $β$ -decay rates of $N$ =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 $^{13}$ C, $^{16}$ O and $^{40}$ 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
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
04
Schwinger model at finite temperature and density with beta VQE
Akio Tomiya🇯🇵
We investigate a quantum gauge theory at finite temperature and density using a variational algorithm for near-term quantum devices. We adapt $β$ -VQE to evaluate thermal and quantum expectation values and study the phase diagram for massless Schwinger model along with the temperature and density. By compering the exact variational free energy, we find the variational algorithm work for $T > 0$ and $μ > 0$ for the Schwinger model. No significant volume dependence of the variational free energy is observed in $μ / g \in [0, 1.4]$ . We calculate the chiral condensate and take the continuum extrapolation. As a result, we obtain qualitative picture of the phase diagram for massless Schwinger model.
↳ hep-lathep-phhep-thnucl-th+116 citations
05
Impact of the Dresden-II and COHERENT neutrino scattering data on neutrino electromagnetic properties and electroweak physics
M. Atzori Corona🇮🇹 · M. Cadeddu🇮🇹 · N. Cargioli🇮🇹 · F. Dordei🇮🇹 · C. Giunti🇮🇹 · Y.F. Li🇨🇳 · C. A. Ternes🇮🇹 · Y.Y. Zhang🇨🇳
Coherent elastic neutrino-nucleus scattering (CE $ν$ NS) represents a powerful tool to investigate key electroweak physics parameters and neutrino properties since its first observation in 2017 by the COHERENT experiment exploiting the spallation neutron source at Oak Ridge National Laboratory. In light of the recent detection of such a process with antineutrinos produced by the Dresden-II reactor scattering off a germanium detector, we revisit the limits so far set on the neutrino magnetic moments, charge radii and millicharges as well as on the weak mixing angle. In order to do so, we also include the contribution of elastic neutrino-electron scattering, whose effect becomes non negligible in some beyond the Standard Model theories. By using different hypotheses for the germanium quenching factor and the reactor antineutrino flux, we provide a measurement of the weak mixing angle at the low-energy scale of the Dresden-II reactor experiment and, thanks to a combined analysis with the latest cesium iodide and argon data set released by the COHERENT Collaboration, we deliver updated limits for the neutrino electromagnetic properties. Interestingly, we are able to set a new best upper limit on the electron neutrino charge radius and significantly improve the other CE $ν$ NS-related limits on the neutrino electric charge and magnetic moment.
↳ hep-phhep-exnucl-exnucl-thJHEP(2022)·81 citations
06
Feasibility of studying astrophysically important charged-particle emission with the variable energy $γ$ -ray system at the Extreme Light Infrastructure -- Nuclear Physics facility
H.Y. Lan · W. Luo · Y. Xu · D.L. Balabanski · G.L. Guardo · M. La Cognata · D. Lattuada · C. Matei · R.G. Pizzone · T. Rauscher · J.L. Zhou
In the environment of a hot plasma, as achieved in stellar explosions, capture and photodisintegration reactions proceeding on excited states in the nucleus can considerably contribute to the astrophysical reaction rate. Such reaction rates including the excited-state contribution are obtained from theoretical calculations as the direct experimental determination of these astrophysical rates is currently unfeasible. In the present study, ( $γ$ ,p) and ( $γ$ , $α$ ) reactions in the mass and energy range relevant to the astrophysical $p$ process are considered and the feasibility of measuring them with the ELISSA detector system at the future Variable Energy $γ$ -ray (VEGA) facility at ELI-NP is investigated. The simulation results reveal that, for the ( $γ$ ,p) reaction on twelve targets of $^{29}$ Si, $^{56}$ Fe, $^{74}$ Se, $^{84}$ Sr, $^{91}$ Zr, $^{96, 98}$ Ru, $^{102}$ Pd, $^{106}$ Cd, and $^{115, 117, 119}$ Sn, and the ( $γ$ , $α$ ) reaction on five targets of $^{50}$ V, $^{87}$ Sr, $^{123, 125}$ Te, and $^{149}$ Sm, the yields of the reaction channels with the transitions to the excited states in the residual nucleus are relevant and even dominant. It is further found that for each considered reaction, the total yields of the charged-particle $X$ may be dominantly contributed from one, two or three ( $γ$ , $X_{i}$ ) channels within a specific, narrow energy range of the incident $γ$ -beam. Furthermore, the energy spectra of the ( $γ$ , $X_{i}$ ) channels with $0 \leq i \leq 10$ are simulated for each considered reaction, with the incident $γ$ -beam energies in the respective energy range as derived before. It becomes evident that measurements of the photon-induced reactions with charged-particle emissions considered in this work are feasible with the VEGA+ELISSA system and will provide knowledge useful for nuclear astrophysics.
↳ nucl-exastro-ph.IMnucl-thPRC(2022)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

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

Nuclear Weak Rates and Nuclear Weak Processes in Stars

Role of non-gaussian quantum fluctuations in neutrino entanglement

Schwinger model at finite temperature and density with beta VQE

Impact of the Dresden-II and COHERENT neutrino scattering data on neutrino electromagnetic properties and electroweak physics

Feasibility of studying astrophysically important charged-particle emission with the variable energy γ-ray system at the Extreme Light Infrastructure -- Nuclear Physics facility

Affiliations

Feasibility of studying astrophysically important charged-particle emission with the variable energy $γ$ -ray system at the Extreme Light Infrastructure -- Nuclear Physics facility