Nuclear Theory·nucl-th

Friday·May 16, 2025

10 papers—6 primary·4 cross-listed

07
Towards testing $(g - 2)_{τ}$ in $e^{+} e^{-} \to τ^{+} τ^{-}$ : radiative corrections and projections for Belle II
Joël Gogniat🇨🇭 · Martin Hoferichter🇨🇭 · Yannick Ulrich🇬🇧
The arguably most promising avenue towards testing physics beyond the Standard Model in the anomalous magnetic moment of the $τ$ proceeds via suitably constructed asymmetries in $e^{+} e^{-} \to τ^{+} τ^{-}$ in the presence of a polarized electron beam. Such a program, as could be realized at Belle II assuming a polarization upgrade of the SuperKEKB $e^{+} e^{-}$ collider, crucially relies on a careful consideration of radiative corrections. In this work, we present the complete one-loop result for the fully polarized $e^{+} e^{-} \to τ^{+} τ^{-}$ process and its implementation in the Monte-Carlo integrator McMule. As an application, we discuss projections relevant for measurements at Belle II, both with and without electron polarization, and outline the necessary steps for a generalization to next-to-next-to-leading order.
↳ hep-phhep-exnucl-thJHEP(2025)·16 citations
08
Neutrino-less double beta decay in the $ν$ Standard Model
Vincenzo Cirigliano🇺🇸 · Wouter Dekens🇺🇸 · Sebastián Urrutia Quiroga🇺🇸
We perform a comprehensive study of the $3 + 3$ Type-I seesaw model for a broad range of right-handed mass scales (from keV to 10 TeV). We take into account and, in some cases, update the constraints from a large number of high- and low-energy experiments and study the implications on neutrino-less double beta ( $0 ν β β$ ) decay experiments. We illustrate our findings through profile likelihood plots for the half-life $T_{1/2}^{0 ν}$ and two-dimensional plots correlating $T_{1/2}^{0 ν}$ to neutrino masses. We find that in this simple class of models for Majorana neutrino masses, current and next-generation $0 ν β β$ decay experiments have a broad discovery potential in both the normal and inverted orderings of the spectrum of light active neutrinos.
↳ hep-phnucl-exnucl-th1 citation
09
Competition between the neutron-proton pair break-ups delineating the level structure of 202Po
Sahab Singh🇮🇳 · D. Choudhury🇮🇳 · B. Maheshwari🇫🇷 · R. Roy🇮🇳 · K. Yadav🇮🇳 · R. Palit🇮🇳 · B. Das🇮🇳 · P. Dey🇮🇳 · A. Kundu🇮🇳 · Md. S. R. Laskar🇮🇳 · D. Negi🇮🇳 · V. Malik🇮🇳 and 9 other authors
High-spin spectroscopic study of $^{202}$ Po ( $Z$ = 84, $N$ = 118) has been carried out using the $^{195}$ Pt( $^{12}$ C, 5n) $^{202}$ Po fusion-evaporation reaction. An extended level scheme has been proposed up to an excitation energy of $E_{x} \approx$ 8 MeV and angular momentum of 27 $ℏ$ , with the addition of 57 newly observed $γ$ -ray transitions, along with the revisions in the placement of 8 already known transitions and the multipolarities of 4 of these transitions. The energy of the unobserved 8 $^{+} \to 6^{+}$ transition has been proposed to be 9.0(5) keV, which resolves the uncertainty in the excitation energy of the levels above the 6 $^{+}$ state. Three new sequences of $M 1$ transitions have also been identified in the high excitation energy regime and included in the proposed level scheme. The large-scale shell model calculations for $Z > 82$ and $N < 126$ valence space have been carried out using PBPOP interaction which explained the overall level scheme for both the positive and negative parity states. The calculations successfully reproduced the purity of the proton $π h_{9/2}$ dominated $8^{+}$ isomeric state, and also explained the missing $E 2$ decay of the $12^{+}$ isomeric state in terms of changing nucleonic configurations.
↳ nucl-exnucl-thPRC(2025)·1 citation
10
Confronting recent light compact star observations with color-flavor locked quark matter
K. Kourmpetis🇩🇪 · P. Laskos-Patkos🇬🇷 · Ch.C. Moustakidis🇬🇷
Recent analyses on the properties of the central compact object in the HESS J1731-347 remnant and the PSR J1231-1411 pulsar indicated that these two compact objects are characterized by similar (low) masses and possibly different radii. This paper aims at reconciling the aforementioned measurements by utilizing the widely employed color-flavor locked (CFL) MIT bag model. The main objective is related to the examination of the acceptable values for the color superconducting gap $Δ$ and the bag parameter $B$ . Furthermore, our analysis involves two distinct hypotheses for the nature of compact stars. Firstly, we considered the case of absolute stability for strange quark matter and we found that it is possible to explain both measurements, while also respecting the latest astronomical constraints on the masses and radii of compact stars. Secondly, we studied the case of hybrid stellar matter (transition from hadrons to quarks), and concluded that, when early phase transitions are considered, the simultaneous reconciliation of both measurements leads to results that are inconsistent to the existence of massive compact stars. However, we showed that all current constraints may be satisfied under the consideration that the HESS J1731-347 remnant contains a slow stable hybrid star.
↳ astro-ph.HEgr-qcnucl-thFront.Astron.Space Sci.(2025)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Towards testing (g−2)τ​ in e+e−→τ+τ−: radiative corrections and projections for Belle II

Neutrino-less double beta decay in the ν Standard Model

Competition between the neutron-proton pair break-ups delineating the level structure of 202Po

Confronting recent light compact star observations with color-flavor locked quark matter

Affiliations

Towards testing $(g - 2)_{τ}$ in $e^{+} e^{-} \to τ^{+} τ^{-}$ : radiative corrections and projections for Belle II

Neutrino-less double beta decay in the $ν$ Standard Model