Nuclear Theory·nucl-th

Monday·December 9, 2024

10 papers—3 primary·7 cross-listed

01
[Submitted on 5 Dec 2024]
Ab initio calculations of overlap integrals for $μ \to e$ conversion in nuclei
Matthias Heinz🇩🇪 · Martin Hoferichter🇨🇭 · Takayuki Miyagi🇯🇵 · Frederic Noël🇨🇭 · Achim Schwenk🇩🇪
The rate for $μ \to e$ conversion in nuclei is set to provide the most stringent test of lepton-flavor symmetry and a window into physics beyond the Standard Model. However, to disentangle new lepton-flavor-violating interactions, in combination with information from $μ \to e γ$ and $μ \to 3 e$ , it is critical that uncertainties at each step of the analysis be controlled and fully quantified. In this regard, nuclear response functions related to the coupling to neutrons are notoriously problematic, since they are not directly constrained by experiment. We address these shortcomings by combining ab initio calculations with a recently improved determination of charge distributions from electron scattering by exploiting strong correlations among charge, point-proton, and point-neutron radii and densities. We present overlap integrals for $^{27}$ Al, $^{48}$ Ca, and $^{48}$ Ti including full covariance matrices, allowing, for the first time, for a comprehensive consideration of nuclear structure uncertainties in the interpretation of $μ \to e$ experiments.
Comments:
13 pages, 10 figures, 5 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2412.04545 [pdf]
PLB(2025)·16 citations
02
[Submitted on 6 Dec 2024]
Impact of the Scalar Isovector $δ$ -meson on the description of nuclear matter and neutron star properties
Lavínia Gabriela Teodoro dos Santos🇵🇹 · Tuhin Malik🇵🇹 · Constança Providência🇵🇹
The implications of including the scalar isovector $δ$ -meson in a relativistic mean-field description of nuclear matter are discussed. A Bayesian inference approach is used to determine the parameters that define the isovector properties of the model. The properties of nuclear matter and neutron stars are discussed. The inclusion of the $δ$ -meson has only a small effect on the maximum mass of the neutron star (NS) and on the speed of sound in its interior, but it has a strong effect on the radius and the tidal deformability of low and medium mass stars. This is mainly due to the effect of the $δ$ -meson on the symmetry energy and its slope and curvature at saturation, increasing the range of possible values of these three properties, and in particular allowing positive values of the symmetry energy curvature. Due to the effect of the $δ$ -meson on the symmetry energy, the proton content of the star is also strongly affected. The inclusion of the $δ$ -meson in the relativistic mean-field description of nuclear matter extends the phase space spanned by the model, allowing for a more flexible density dependence of the symmetry energy compatible with experimental, observational, and ab initio constraints.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2412.04946 [pdf]
PRC(2025)·9 citations
03
[Submitted on 6 Dec 2024]
Excited cluster states: A new source for proton number fluctuations in the high baryon density regime
Boris Tomasik🇸🇰 · Marcus Bleicher🇩🇪
We calculate the contribution of the decay products of excited nuclear cluster states to the event-by-event fluctuations of protons in the energy range from $s_{N N} = 2 - 5$ ~GeV within the statistical model. We find that the inclusion of the excited nuclear clusters yields corrections to all cumulant ratios, ranging from 1\% for ratio of second to first-order cumulant to 100\% for the sixth to second order cumulant towards the lowest inspected energy. As expected the contribution of excited cluster states is most important at low energies $s_{N N} < 3.5$ ~GeV and becomes negligible at higher collision energies. Especially in light of the expected ultra-high precision data from CBM at FAIR, this new contribution is important to allow for a quantitative comparison with (potentially later available) lattice QCD or effective model results.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2412.04994 [pdf]
PLB(2025)·0 citations
04
[Submitted on 5 Dec 2024] (cross-list from astro-ph.HE)
Open-source library for performance-portable neutrino reaction rates: Application to neutron star mergers
Leonardo Chiesa🇮🇹 · Maitraya Bhattacharyya🇺🇸 · Filippo Mazzini🇮🇹 · Federico Maria Guercilena🇮🇹 · Albino Perego🇮🇹 · David Radice🇺🇸
A realistic and detailed description of neutrinos in binary neutron star (BNS) mergers is essential to build reliable models of such systems. To this end, we present BNS_NURATES, a novel open-source numerical library designed for the efficient on-the-fly computation of neutrino interactions, with particular focus on regimes relevant to BNS mergers. BNS_NURATES targets a higher level of accuracy and realism in the implementation of commonly employed reactions by accounting for relevant microphysics effects on the interactions, such as weak magnetism and mean field effects. It also includes the contributions of inelastic neutrino scattering off electrons and positrons and (inverse) nucleon decays. Finally, it offers a way to reconstruct the neutrino distribution function in the framework of moment-based transport schemes. As a first application, we compute both energy-dependent and energy-integrated neutrino emissivities and opacities for conditions extracted from a BNS merger simulation with M1 transport scheme. We find some qualitative differences in the results when considering the impact of the additional relevant reactions and of microphysics effects. For example, neutrino-electron/positron scattering reactions are important for the energy exchange of heavy-type neutrinos as they do not undergo semileptonic charged-current processes, when $μ^{\pm}$ are not accounted for. Moreover, weak magnetism and mean field effects can significantly modify the contribution of $β$ processes for electron-type (anti)neutrinos, increasing at the same time the importance of (inverse) neutron decays. The improved treatment for the reaction rates also modifies the conditions at which neutrinos decouple from matter in the system, potentially affecting their emission spectra.
Comments:
28 pages, 15 figures, published in PRD. The BNS_NURATES library is publicly available at: https://github.com/RelNucAs/bns_nurates
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2412.04570 [pdf]
PRD(2025)·13 citations
05
[Submitted on 6 Dec 2024] (cross-list from hep-ph)
Photon vortex generation from nonlinear Compton scattering in Feynman approach
Tomoyuki Maruyama🇯🇵 · Takehito Hayakawa🇯🇵 · Ryoichi Hajima🇯🇵 · Toshitaka Kajino🇨🇳 · Myung-Ki Cheoun🇰🇷
In the present study, we show calculation of nonlinear Compton scattering with circularly polarized photons in a cylindrical coordinate using Feynman diagram to calculate photon vortex generation in intermediate states considering conservation of angular momentum. We take two different vortex wave functions based on Bessel function for the emitted photon and the electron after emission of the photon, which are the eigenstate of z component of the total angular momentum (zTAM) when a particle propagates along z axis. The result shows that when an electron absorbs N photons a photon vortex with a zTAM = N is predominantly radiated, but there are still very small contributions of photons with a zTAM = (N-1) and (N +1) due to the spin flip of the initial electron. This means even when an electron absorbs only a single photon, the electron may emit a photon vortex of a zTAM of 2 h-bar. However, the numerical calculations show that the contribution of the spin flip is four orders of magnitude smaller than that of the dominant radiation. We also discuss the circular polarization for the generated photon vortices.
Comments:
19 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); physics.optics (physics.optics)
arXiv:
2412.04709 [pdf]
PRD(2025)·1 citation
06
[Submitted on 6 Dec 2024] (cross-list from hep-ph)
Neutrino-nucleon elastic scattering in presence of non-standard interactions: cross sections and nucleon polarizations
Ilma🇮🇳 · M. Rafi Alam🇮🇳 · L. Alvarez-Ruso🇪🇸 · M. Benitez Galan🇪🇸 · I. Ruiz Simo🇪🇸 · S. K. Singh🇮🇳
New physics beyond the Standard Model (SM) may appear in the form of non-standard neutrino interactions (NSI). We have studied neutral current (anti)neutrino-nucleon scattering in presence of NSI. We obtain that in this scenario, nucleon matrix elements depend not only on the isovector axial nucleon form factor but also on the isoscalar one. For the axial form factors we consequently rely on the quark flavor decomposition performed by QCD simulations in the lattice (LQCD). We have examined cross sections and polarization observables. For the current bounds on diagonal muon flavor NSI couplings we find substantial deviations from the SM predictions in cross sections and transverse polarizations of the outgoing nucleons. In view of the progress in the precision of LQCD determinations of nucleon properties, modern measurements of neutral current (anti)neutrino-nucleon scattering will be in the position to discover or significantly constrain NSI.
Comments:
13 pages, 6 figures and 2 tables. This version matches the accepted one in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2412.04818 [pdf]
PRD(2025)·4 citations
07
[Submitted on 6 Dec 2024] (cross-list from hep-ph)
Tripling Fluctuations and Peaked Sound Speed in Fermionic Matter
Hiroyuki Tajima🇯🇵 · Kei Iida🇯🇵 · Toru Kojo🇯🇵 · Haozhao Liang🇯🇵
A crossover involving three-fermion clusters is relevant to the hadron-quark crossover, which, if occurring in a neutron star, could naturally reproduce the dense-matter equation of state recently deduced from simultaneous observations of neutron-star masses and radii. To understand the crossover mechanism, we examine the role of tripling fluctuations induced by the formation of three-fermion clusters. The phase-shift representation of fluctuations manifests an interplay of bound and scattering states, leading to non-monotonic momentum distributions of baryon-like clusters and peaked sound speed at finite densities. We demonstrate them by applying our approach to a nonrelativistic system of one-dimensional three-color fermions analogous to the hadron-quark matter.
Comments:
7 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2412.04971 [pdf]
PRL(2025)·12 citations
08
[Submitted on 6 Dec 2024] (cross-list from hep-ph)
Born-Oppenheimer Renormalization group for High Energy Scattering: the Setup and the Wave Function
Haowu Duan🇺🇸 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱
We develop an approach to QCD evolution based on the sequential Born-Oppenheimer approximations that include higher and higher frequency modes as the evolution parameter is increased. This Born-Oppenheimer renormalization group is a general approach which is valid for the high energy evolution as well as the evolution in transverse resolution scale $Q^{2}$ . In the former case it yields the frequency ordered formulation of high energy evolution, which includes both the eikonal splittings which produce gluons with low longitudinal momentum, and the DGLAP-like splittings which produce partons with high transverse momentum. In this, first paper of the series we lay out the formulation of the approach, and derive the expression for the evolved wave function of a hadronic state. We also discuss the form of the $S$ -matrix which is consistent with the frequency ordering.
Comments:
41 pages; 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2412.05085 [pdf]
JHEP(2025)·9 citations
09
[Submitted on 6 Dec 2024] (cross-list from hep-ph)
Born-Oppenheimer Renormalization group for High Energy Scattering: CSS, DGLAP and all that
Haowu Duan🇺🇸 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱
In \cite{one}, we have introduced the Born-Oppenheimer (BO) renormalization group approach to high energy hadronic collisions and derived the BO approximation for the light cone wave function of a fast moving projectile hadron. In this second paper, we utilize this wave function to derive the BO evolution of partonic distributions in the hadron -- the gluon transverse momentum and integrated parton distributions (TMD and PDF respectively). The evolution equation for the TMD contains a linear and a nonlinear term. The linear term reproduces the Collins-Soper-Sterman (CSS) equation with a physical relation between the transverse and longitudinal resolution scales. We explain how this equivalence arises, even though the BO and CSS cascades are somewhat different in structures. The nonlinear term in the evolution has a very appealing physical meaning: it is a correction due to stimulated emission, which enhances emission of gluons (bosons) into states with a nonzero occupation. For the evolution of the PDF we again find a linear and nonlinear term. At not very small Bjorken $x$ , the linear term recovers the DGLAP equation in the leading logarithmic approximation. At small $x$ however there are contributions from gluon splittings which are in the BFKL kinematics leading to a modification of the DGLAP equation. The nonlinear terms have the same physical origin as in the equation for the TMD -- the stimulated emission corrections. Interestingly the nonlinear corrections are the most important for the virtual terms, so that the net correction to the DGLAP is negative and mimics shadowing, although the physical origin of the nonlinearity is very different.
Comments:
33 pages; 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2412.05097 [pdf]
JHEP(2025)·18 citations
10
[Submitted on 6 Dec 2024] (cross-list from hep-ph)
Masquerading hybrid stars with dark matter
Carline Biesdorf🇧🇷 · Jürgen Schaffner-Bielich🇩🇪 · Laura Tolos🇪🇸
We investigate the influence of dark matter on hybrid stars. Using a two-fluid approach, where normal and dark matter components interact only gravitationally, we explore how dark matter can trigger the appearance of quark matter in neutron stars for unprecedented low masses. Our findings reveal that dark matter increases the central pressure of neutron stars, potentially leading to the formation of hybrid stars with quark cores even at very low compact star masses. The critical mass for the appearance of quark matter decreases with increasing dark matter content. We introduce the concept of "masquerading hybrid stars", where dark matter admixed stars exhibit similar mass-radius relations to purely hadronic stars, making it challenging to distinguish between them based solely on these parameters. Additionally, we identify a unique class of objects termed "dark oysters", characterized by a large dark matter halo and a small normal matter core, highlighting the diverse structural possibilities for compact stars influenced by dark matter.
Comments:
16 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2412.05207 [pdf]
PRD(2025)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE