Nuclear Theory·nucl-th

Wednesday·May 3, 2023

8 papers—4 primary·4 cross-listed

01
Quantum information and quantum simulation of neutrino physics
A. B. Balantekin🇺🇸 · Michael J. Cervia🇺🇸 · Amol V. Patwardhan🇺🇸 · Ermal Rrapaj🇺🇸 · Pooja Siwach🇺🇸
In extreme astrophysical environments such as core-collapse supernovae and binary neutron star mergers, neutrinos play a major role in driving various dynamical and microphysical phenomena, such as baryonic matter outflows, the synthesis of heavy elements, and the supernova explosion mechanism itself. The interactions of neutrinos with matter in these environments are flavor-specific, which makes it of paramount importance to understand the flavor evolution of neutrinos. Flavor evolution in these environments can be a highly nontrivial problem thanks to a multitude of collective effects in flavor space, arising due to neutrino-neutrino ( $ν$ - $ν$ ) interactions in regions with high neutrino densities. A neutrino ensemble undergoing flavor oscillations under the influence of significant $ν$ - $ν$ interactions is somewhat analogous to a system of coupled spins with long-range interactions among themselves and with an external field ('long-range' in momentum-space in the case of neutrinos). As a result, it becomes pertinent to consider whether these interactions can give rise to significant quantum correlations among the interacting neutrinos, and whether these correlations have any consequences for the flavor evolution of the ensemble. In particular, one may seek to utilize concepts and tools from quantum information science and quantum computing to deepen our understanding of these phenomena. In this article, we attempt to summarize recent work in this field. Furthermore, we also present some new results in a three-flavor setting, considering complex initial states.
nucl-thastro-ph.HEhep-phquant-phEPJA(2023)·44 citations
02
Properties of quark matter and hybrid stars from a quasiparticle model
He Liu🇨🇳 · Yong-Hang Yang🇨🇳 · Yue Han🇨🇳 · Peng-Cheng Chu🇨🇳
We investigate the properties of hybrid stars with the hadron-quark phase transition by using a quasiparticle model. Results from our study indicate that the coupling constant $g$ can stiffen the EOS of hybrid star matter and thus increase the hybrid star maximum mass and its tidal deformability, whereas it also decreases the mass and radius of the pure quark core. In addition, we find that a step change of the sound velocity occurs in the hadron-quark mixed phase, and it is restored with the decrease of nucleon and lepton degrees of freedom in the high density quark phase. The approximate rule that the polytropic index $γ \leq 1.75$ can also be used as a criterion for separating hadronic from quark matter in our work. The hypothesis of absolutely stable SQM (or "Witten hypothesis") suggests that a hybrid star containing a sufficient amount of SQM in its core will rapidly convert into a strange quark star. The SQM in hybrid stars therefore should break the absolutely stable condition, and the energy per nucleon ( $E / A$ ) of both $u d$ QM and SQM must exceed the lowest energy per nucleon 930 MeV. As a result, we provide the maximum mass, minimum radius $R_{1.4}$ and minimum tidal deformation $Λ_{1.4}$ of the hybrid stars as well as the maximum mass and radius of the quark matter core with different $g$ values within the allowable regions ( $E / A > 930$ MeV) on the $g - B^{1/4}$ plane. Using the constraints from astrophysical observations and heavy-ion experiments for comparison, our results indicate that the recently discovered massive neutron stars be well described as hybrid stars in the quasiparticle model, and confirm that the sizable quark-matter cores ( $R_{QC} > 6.5$ km) containing the mixed phase can appear in $2 M_{⊙}$ massive stars.
nucl-thPRD(2023)·16 citations
03
On-Shell Calculation of Mixed Electromagnetic and Gravitational Scattering
Barry R. Holstein🇺🇸
The study of long-range effects arising from the higher order exchange of massless particles via summation of Feynman diagrams is well known, but recently it has been shown that the use of on-shell methods can provide a streamlined route to the calculation of both electromagnetic and gravitational effects. In this note we demonstrate that the use of on-shell methods yields a similar simplification in the evaluation of higher order effects in the case of mixed electromagnetic and gravitational scattering.
nucl-thgr-qchep-phPRD(2023)·3 citations
04
Production of n-rich nuclei in red giant stars
Maurizio M. Busso · Sara Palmerini
We outline a partial historical summary of the steps through which the nucleosynthesis phenomena induced by {\it slow} neutron captures (the {\it s-process}) were clarified, a scientific achievement in which Franz Käppeler played a major role. We start by recalling the early phenomenological approach, which yielded a basic understanding of the subject even before models for the parent stellar evolutionary stages were developed. Through such a tool, rough limits for the neutron density and exposure were set, and the crucial fact was understood that more than one nucleosynthesis component is required to account for solar abundances of $s$ -process nuclei up to the Pb-Bi region. We then summarize the gradual understanding of the stellar processes actually involved in the production of nuclei from Sr to Pb (the so-called {\it Main Component}, achieved in the last decade of the past century and occurring in red giants of low and intermediate mass, ( $M ≲$ 8 $M_{⊙}$ ), populating, in the {\it HR} diagram, the {\it Asymptotic Giant Branch} or {\it AGB} region. We conclude by giving some details on more recent research concerning mixing mechanisms inducing the activation of the main neutron source, $^{13}$ C( $α$ ,n) $^{16}$ O.
nucl-thastro-ph.SREPJA(2023)·1 citation
05
Bayesian Inference of Supernova Neutrino Spectra with Multiple Detectors
Xu-Run Huang🇨🇳 · Chuan-Le Sun🇨🇳 · Lie-Wen Chen🇨🇳 · Jun Gao🇨🇳
We implement the Bayesian inference to retrieve energy spectra of all neutrinos from a galactic core-collapse supernova (CCSN). To achieve high statistics and full sensitivity to all flavours of neutrinos, we adopt a combination of several reaction channels from different large-scale neutrino observatories, namely inverse beta decay on proton and elastic scattering on electron from Hyper-Kamiokande (Hyper-K), charged current absorption on Argon from Deep Underground Neutrino Experiment (DUNE) and coherent elastic scattering on Lead from RES-NOVA. Assuming no neutrino oscillation or specific oscillation models, we obtain mock data for each channel through Poisson processes with the predictions, for a typical source distance of 10 kpc in our Galaxy, and then evaluate the probability distributions for all spectral parameters of theoretical neutrino spectrum model with Bayes' theorem. Although the results for either the electron-neutrinos or electron-antineutrinos reserve relatively large uncertainties (according to the neutrino mass hierarchy), a precision of a few percent (i.e., $\pm 1% \sim \pm 4%$ at a credible interval of $2 σ$ ) is achieved for primary spectral parameters (e.g., mean energy and total emitted energy) of other neutrino species. Moreover, the correlation coefficients between different parameters are computed as well and interesting patterns are found. Especially, the mixing-induced correlations are sensitive to the neutrino mass hierarchy, which potentially makes it a brand new probe to determine the neutrino mass hierarchy in the detection of galactic supernova neutrinos. Finally, we discuss the origin of such correlation patterns and perspectives for further improvement on our results.
↳ hep-phastro-ph.HEnucl-exnucl-thJCAP(2023)·10 citations
06
Detecting the critical point through entanglement in Schwinger model
Kazuki Ikeda🇺🇸 · Dmitri E. Kharzeev🇺🇸 · René Meyer🇩🇪 · Shuzhe Shi🇺🇸
Using quantum simulations on classical hardware, we study the phase diagram of the massive Schwinger model with a $θ$ -term at finite chemical potential $μ$ . We find that the quantum critical point in the phase diagram of the model can be detected through the entanglement entropy and entanglement spectrum. As a first step, we chart the phase diagram using conventional methods by computing the dependence of the charge and chiral condensates on the fermion mass $m$ , coupling constant $g$ , and the chemical potential $μ$ . At zero density, the Schwinger model possesses a quantum critical point at $θ = π$ and $m / g ≃ 0.33$ . We find that the position of this quantum critical point depends on the chemical potential. Near this quantum critical point, we observe a sharp maximum in the entanglement entropy. Moreover, we find that the quantum critical point can be located from the entanglement spectrum by detecting the position of the gap closing point.
↳ hep-phcond-mat.str-elhep-exhep-lat+2PRD(2023)·36 citations
07
Effect of finite nuclear size on the electric quadrupole hyperfine operator
V. A. Dzuba · V. V. Flambaum
We present an expression for the operator of the electric quadrupole hyperfine interaction which takes into account finite nuclear size. We compare the results obtained with the use of this operator with those obtained in the standard approach which ignores finite nuclear size. We found that the effect of changing operators on the hyperfine constant $B$ is small in hydrogen-like systems. There is a very significant enhancement of the effect in many-electron atoms caused by the contribution of the large $s_{1/2} - d_{3/2}, d_{5/2}$ and $p_{1/2} - p_{3/2}$ off diagonal matrix elements to the core polarisation, correlation and configuration interaction corrections. Similar enhancement takes place for transition amplitudes induced by the electric quadrupole hyperfine interaction.
↳ physics.atom-phnucl-th0 citations
08
Dynamics in near-threshold $J / ψ$ photoproduction
JPAC Collaboration: D. Winney🇨🇳 · C. Fernandez-Ramirez🇪🇸 · A. Pilloni🇮🇹 · A. N. Hiller Blin🇩🇪 · M. Albaladejo🇪🇸 · L. Bibrzycki🇵🇱 · N. Hammoud🇵🇱 · J. Liao🇺🇸 · V. Mathieu🇪🇸 · G. Montana🇺🇸 · R. J. Perry🇪🇸 · V. Shastry🇺🇸 · W. A. Smith🇺🇸 · A. P. Szczepaniak🇺🇸
The study of $J / ψ$ photoproduction at low energies has consequences for the understanding of multiple aspects of nonperturbative QCD, ranging from mechanical properties of the proton, to the binding inside nuclei, and the existence of hidden-charm pentaquarks. Factorization of the photon- $c c ˉ$ and nucleon dynamics or Vector Meson Dominance are often invoked to justify these studies. Alternatively, open charm intermediate states have been proposed as the dominant mechanism underlying $J / ψ$ photoproduction. As the latter violates this factorization, it is important to estimate the relevance of such contributions. We analyse the latest differential and integrated photoproduction cross sections from the GlueX and $J / ψ$ -007 experiments. We show that the data can be adequately described by a small number of partial waves, which we parameterize with generic models enforcing low-energy unitarity. The results suggest a nonnegligible contribution from open charm intermediate states. Furthermore, most of the models present an elastic scattering length incompatible with previous extractions based on Vector Meson Dominance, and thus call into question its applicability to heavy mesons. Our results indicate a wide array of physics possibilities that are compatible with present data and need to be disentangled.
↳ hep-phhep-exnucl-thPRD(2023)·61 citations

Affiliations

first authorsco-authorsvia INSPIRE