Nuclear Theory·nucl-th

Friday·July 11, 2025

6 papers—1 primary·5 cross-listed

02
[Submitted on 9 Jul 2025] (cross-list from hep-ph)
Amplifying muon-to-positron conversion in nuclei with ultralight dark matter
Purushottam Sahu🇮🇳 · Manibrata Sen🇮🇳
We present an analysis of the lepton-number and lepton-flavour-violating process of muon-to-positron conversion $μ^{-} + N \to e^{+} + N^{'}$ , in the presence of an ultralight scalar dark matter (ULSDM) field which couples to neutrinos. The ULSDM contributes to the effective off-diagonal Majorana mass $m_{μ e}$ , therefore amplifying the rate of muon-to-positron conversion to experimentally observable levels. Using existing bounds from SINDRUM II, COMET, and Mu2e experiments, we derive novel constraints on the flavour-off-diagonal couplings of neutrinos to ULSDM. Our work reveals that upcoming experiments can provide stronger sensitivity to these new couplings than bounds arising from cosmological surveys and terrestrial experiments.
Comments:
Invited edition for the special issue of Emerging Leaders 2025 in the Journal of Physics G: Nuclear and Particle Physics, 8 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2507.07176 [pdf]
J.Phys.G(2026)·1 citation
03
[Submitted on 9 Jul 2025] (cross-list from hep-ph)
Chiral Cherenkov radiation in the presence of a time-dependent chiral chemical potential
Kirill Tuchin🇺🇸
The photon production process $f \to f + γ$ in the presence of a time-dependent chiral chemical potential $μ_{5}$ is studied. The validity of the adiabatic approximation is demonstrated in the ultra-relativistic limit. Analytical expressions for the photon spectrum are derived for two models of the chiral magnetic conductivity $b_{0} \propto μ_{5}$ : (i) $b_{0} (t) = A_{1} + B_{1} tanh (t / τ)$ and (ii) $b_{0} (t) = A_{2} (t / τ) / (1 + t^{2} / τ^{2})$ . It is known that for constant $b_{0}$ , photon emission may exhibit a resonance for one photon polarization depending on the sign of $b_{0}$ . It is shown that in model (i), up to two resonances may occur, depending on the sign of the asymptotic values $b_{0} (\infty)$ and $b_{0} (- \infty)$ . No resonances are observed in model (ii). Numerical calculations are performed using parameters relevant to quark-gluon plasma, and the universality of the results is discussed.
Comments:
11 pages, 5 figures, v2: minor stylistic improvements
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2507.07324 [pdf]
PRC(2025)·4 citations
04
[Submitted on 10 Jul 2025] (cross-list from hep-ph)
Thermodynamic Analysis of Transverse Momentum Spectra in Pb-Pb Collisions at 2.76 TeV: Centrality Dependence of Temperature, Freezeout Parameters and Non-Extensitivity
M. Waqas🇨🇳 · Hassan Ali Khan🇨🇳 · Wolfgang Bietenholz🇲🇽 · Muhammad Ajaz🇵🇰 · Jihane Ben Slimane🇸🇦 · Haifa I. Alrebdi🇸🇦 · A. Haj Ismail🇦🇪
We study properties of Pb-Pb collisions at 2.76 TeV in mid-rapidity, $∣ y ∣ < 0.5$ , based on data by the ALICE Collaboration. In particular, we examine the transverse momentum ( $p_{T}$ ) spectra of positively charged (identified) hadrons, $π^{+}$ , $K^{+}$ and $p$ , generated in various centrality intervals. We perform individual fits using the thermodynamically consistent Tsallis distribution to extract the following quantities: the non-extensitivity parameter, $q$ , the effective temperature, $T_{eff}$ , the kinetic freezeout volume, $V$ , the mean transverse flow velocity, $β_{T}$ , the mean kinetic freezeout temperature, $⟨ T_{0} ⟩$ , the thermal temperature, $T_{th}$ , and the parameter $ζ$ , which characterizes the fluctuating number of generated particles. From peripheral to central collision, and from lower to higher charged particle multiplicity per pseudorapidity unit, $⟨ d N_{ch} / d η ⟩$ , all these quantities are observed to increase, with the exception of $q$ , which has the opposite behavior. The parameters $T_{eff}$ , $q$ , and $V$ depend on the hadron mass in a way that supports the scenarios of volume differential freezeout and multiple kinetic freezeout. Furthermore, we extracted $⟨ T_{eff} ⟩$ and $⟨ q ⟩$ for different collisions and energies at LHC and RHIC, and compare their dependencies on $⟨ d N_{ch} / d η ⟩$ and $⟨ N_{part} ⟩$ .
Comments:
18 pages, LaTex, 7 figures, to appear in Eur. Phys. J. A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2507.07369 [pdf]
EPJA(2025)·1 citation
05
[Submitted on 10 Jul 2025] (cross-list from hep-ph)
New Isobar Models for $K^{+} Λ$ Electroproduction
Jovan Alfian Djaja🇮🇩 · Terry Mart🇮🇩
The electroproduction of kaon on proton has been studied using two covariant isobar models. The models incorporate propagators and vertex factors developed in our previous works. In total, the current study includes 26 nucleon resonances and 20 hyperon resonances, with spins up to 13/2. In the electromagnetic vertices, we consider two alternative electromagnetic form factors alongside the commonly used dipole model. The unknown parameters in the models, such as longitudinal coupling constants and form factor cutoffs, are determined by fitting the calculated observables to nearly 2000 experimental data points. The resulting models demonstrate satisfactory consistency with the available experimental data.
Comments:
Contribution to the 14th International Physics Seminar (IPS) 2025
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2507.07750 [pdf]
J.Phys.Conf.Ser.(2025)·1 citation
06
[Submitted on 10 Jul 2025] (cross-list from hep-ph)
Femtoscopy of $D N$ and $D ˉ N$ systems
Mikel F. Barbat🇪🇸 · Juan M. Torres-Rincon🇪🇸 · Angels Ramos🇪🇸 · Laura Tolos🇪🇸
The capability of the ALICE@LHC and STAR@RHIC experiments to reconstruct $D$ mesons has enabled femtoscopic correlation measurements of open-charm mesons in both small and large systems. In this work, we present a theoretical calculation of the correlation functions of $D$ and $D ˉ$ mesons with nucleons, based on the Koonin-Pratt formalism. We employ an effective Lagrangian to model the interaction between charmed mesons and baryons and apply the TROY formalism to obtain the off-shell $T$ -matrix in coupled channels, incorporating the effect of the Coulomb interaction when the pair involves two charged particles. The resulting full coupled-channel wave function is inserted into the Koonin-Pratt equation with channel weights derived from a thermal model. Additionally, we compute the correlation functions using the Lednický-Lyuboshitz approximation with low-energy scattering parameters extracted from the unitarized amplitudes. We compare these two approaches and provide predictions for different correlated pairs. Our results can be tested against current and future experimental data from the ALICE and STAR collaborations in both proton-proton and heavy-ion collisions.
Comments:
15 pages, 10 figures. Appendix added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2507.07864 [pdf]
PRD(2026)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Amplifying muon-to-positron conversion in nuclei with ultralight dark matter

Chiral Cherenkov radiation in the presence of a time-dependent chiral chemical potential

Thermodynamic Analysis of Transverse Momentum Spectra in Pb-Pb Collisions at 2.76 TeV: Centrality Dependence of Temperature, Freezeout Parameters and Non-Extensitivity

New Isobar Models for K+Λ Electroproduction

Femtoscopy of DN and DˉN systems

Affiliations

New Isobar Models for $K^{+} Λ$ Electroproduction

Femtoscopy of $D N$ and $D ˉ N$ systems