Nuclear Theory·nucl-th

Thursday·June 25, 2026

8 papers—4 primary·4 cross-listed

05
[Submitted on 23 Jun 2026] (cross-list from nucl-ex)
Low lying excitations in $^{150}$ Pm
A. Pal · S. Basak · T. Bhattacharjee · Nazira Nazir · G. H. Bhat · S. Jehangir · D. Kumar · A. Saha · S. S. Alam · D. Banerjee · A. Das · A. Adhikari and 10 other authors
The low lying excitations in odd-odd $^{150}$ Pm have been studied through proton induced reaction with an array of five Compton suppressed Clover HPGe and one segmented planar Ge detectors. The relative excitation functions for the observed $γ$ rays have been studied using singles data at two beam energies of 8~MeV and 9~MeV. 16 new $γ$ rays and 15 new levels have been placed in the level scheme of $^{150}$ Pm based on $γ - γ$ coincidence data. The relative intensities for the observed $γ$ rays have been determined using total and gated projections. Tentative spin-parity assignments were made to few low lying excitations of $^{150}$ Pm, using limited angular distribution data and other information. Lifetimes were estimated for two excited levels in this nucleus using using generalized centroid difference analysis, applied in the nanosecond range, with Ge detectors. Large basis shell model and projected shell model calculation were performed to interpret the experimentally observed levels. The present work indicates 1 $^{-}$ ground state, a 2 $^{-}$ state close to the ground state ( $\sim$ 50~keV) and a low lying 6 $^{-}$ isomeric state in this odd-odd nucleus along with emerging band structures developed with two quasiparticle configurations.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2606.25093 [pdf]
0 citations
06
[Submitted on 24 Jun 2026] (cross-list from astro-ph.HE)
Amortized Simulation-Based Inference of Relativistic Mean-Field Couplings for Neutron-Star Equations of State
Prashant Thakur🇰🇷 · Tuhin Malik🇵🇹
We present a simulation-based inference framework for constraining microscopic relativistic mean-field parameters of neutron-star equations of state. Neural posterior estimation is applied to two representative RMF families, a density-dependent DDB model and a nonlinear RMF-NL model, using nuclear saturation properties, chiral effective-field-theory pure-neutron-matter pressures, and the maximum-mass constraint as conditioning observables. The inferred posteriors are validated against the conventional nested sampler (PyMultiNest) calculations and tested with the TARP coverage diagnostic. For both RMF parametrizations, the neural posterior reproduces the nested-sampling constraints on model couplings, nuclear-matter properties, and neutron-star observables with no significant bias. The amortized estimator generates $3 \times 1 0^{4}$ posterior samples in about $2.5 s$ on a CPU, enabling a rapid inference workflow without the need for retraining for updated data. This constitutes a proof of concept that NPE-emulated RMF models, once validated, can be safely used for superfast exploratory inference. As an additional mock-observation test, imposing $R_{1.4} = 12 km$ and $M_{max} > 1.97 M_{⊙}$ leads to consistent predictions for the maximum-mass configuration, with DDB giving $M_{max} = 2.1 0_{- 0.07}^{+ 0.09} M_{⊙}$ , $R_{max} = 10.7 1_{- 0.21}^{+ 0.14} km$ and RMF-NL giving $M_{max} = 2.0 5_{- 0.06}^{+ 0.10} M_{⊙}$ , $R_{max} = 10.6 9_{- 0.19}^{+ 0.18} km$ ; although fixing $R_{1.4}$ confines both families to a narrow EOS region, RMF-NL remains marginally softer than DDB at high density, consistent with its slightly lower maximum mass.
Comments:
7 figures, 3 Tables
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2606.25446 [pdf]
0 citations
07
[Submitted on 24 Jun 2026] (cross-list from hep-ph)
In-medium QCD splittings beyond the soft, large- $N_{c}$ and harmonic-oscillator approximations all at once
Marco Leitão🇫🇷 · José Guilherme Milhano🇵🇹 · Alba Soto-Ontoso🇪🇸
Nearly thirty years ago, Baier, Dokshitzer, Mueller, Peigné, Schiff, and Zakharov (BDMPS-Z) introduced a formalism to calculate the fully differential probability for a high-energy quark or gluon to radiate inside a finite-volume QCD plasma. We report on the first, complete numerical solution to the BDMPS-Z equations for in-medium QCD splittings. Our numerical routines are precise across phase-space, enabling a determination of the in-medium splitting functions that is significantly beyond the state-of-the-art, including finite-energy effects, subleading-color contributions, and a realistic model for parton-medium interactions. We quantify the uncertainties associated with standard approximations in the literature, revealing substantial deviations across phase-space. This work opens a path toward more precise calculations of jet observables and for powerful new constraints of medium parameters from high-energy heavy-ion collider data.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2606.26039 [pdf]
2 citations
08
[Submitted on 24 Jun 2026] (cross-list from hep-ph)
Positron-Emitting and Electron-Capturing Double-Beta Processes in the Standard Model and Beyond
Lukáš Gráf🇨🇿 · Jenni Kotila🇫🇮 · Oliver Scholer🇺🇸
We study positron-emitting and electron-capturing double-beta-decay modes as probes complementary to the usual double beta decay. Motivated by the proposed NuDoubt++ experiment, we analyze the candidate isotopes $^{78}$ Kr, $^{106}$ Cd, and $^{124}$ Xe, providing nuclear matrix elements and phase-space factors for both neutrinoful and neutrinoless modes. For the Standard-Model channels, we find that $2 ν$ ECEC and $2 ν β^{+}$ EC are the most experimentally accessible, whereas $2 ν β^{+} β^{+}$ remains strongly phase-space suppressed. For the neutrinoless channel, we interpret a projected sensitivity of $T_{1/2}^{0 ν} = 1 0^{24}$ y in terms of dimension-seven SMEFT operators and find sensitivity to lepton-number-violating new-physics scales of order 1-100 TeV. We further show that measurements in multiple isotopes can help to resolve degeneracies in multi-operator scenarios, making positron-emitting double-beta searches a useful complement to conventional neutrinoless double beta decay experiments.
Comments:
27 pages, 8 figures, 5 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2606.26097 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Low lying excitations in 150Pm

Amortized Simulation-Based Inference of Relativistic Mean-Field Couplings for Neutron-Star Equations of State

In-medium QCD splittings beyond the soft, large-Nc​ and harmonic-oscillator approximations all at once

Positron-Emitting and Electron-Capturing Double-Beta Processes in the Standard Model and Beyond

Affiliations

Low lying excitations in $^{150}$ Pm

In-medium QCD splittings beyond the soft, large- $N_{c}$ and harmonic-oscillator approximations all at once