Nuclear Theory·nucl-th

Tuesday·November 18, 2025

11 papers—6 primary·5 cross-listed

07
Fermi-Dirac Wigner function for massive spin-1/2 particles in local equilibrium
Sudip Kumar Kar · Valeriya Mykhaylova
A recently proposed Boltzmann local equilibrium Wigner function for massive spin-1/2 particles is generalized to the case of Fermi-Dirac statistics. The resulting formula ensures the correct normalization of the mean polarization vector and reproduces the generalized thermodynamic relations with spin that were obtained in earlier studies. Moreover, we show that the macroscopic currents constructed from the Fermi-Dirac Wigner function can be obtained as derivatives of a suitably defined generating function with respect to the Lagrange multipliers (temperature, hydrodynamic flow, and chemical potentials). The identified generating function also indicates that the underlying framework can be classified as a divergence-type theory.
↳ quant-phhep-phnucl-th5 citations
08
A Study of $T_{cc} (3875)^{+}$ Nature : Compact v.s. Molecule
Shota Ampuku · Yasuhiro Yamaguchi · Masayasu Harada
A central question in exotic-hadron physics is their internal structure whether these states are loosely bound hadronic molecules or compact multiquark configurations. To shed light on this issue, we develop a model that incorporates mixing between hadronic-molecular and compact multiquark components. We then apply this framework to the specific case of the $T_{cc} (3875)^{+}$ and analyze the peak structure in the $D^{0} D^{0} π^{+}$ invariant-mass spectrum reported by LHCb. We find that a scenario based on a predominantly compact tetraquark provides the best fitted solution which can explain the $T_{cc} (3875)^{+}$ . We also find that the model admits two more solutions of comparable quality, both of which imply that the $T_{cc} (3875)^{+}$ is a molecular state: (1) the $T_{cc} (3875)^{+}$ is a $D^{*+} D^{0}$ molecule and there is a $D^{* 0} D^{+}$ molecular state in addition; (2) the $T_{cc} (3875)^{+}$ is a $D^{* 0} D^{+}$ molecule and an aditional $D^{*+} D^{0}$ molecular state is found below $D^{0} D^{0} π^{+}$ threshold. These molecular states are not simple $I = 0$ states, but mixtures of $I = 0$ and $I = 1$ states. We show that all three scenarios are also consistent with the experimentally observed near-threshold $D^{0} D^{0}$ and $D^{0} D^{+}$ invariant-mass distributions.
↳ hep-phnucl-th0 citations
09
Prospects for a Solid-State Nuclear Clock
Steven M. Girvin (Yale) · Leo Radzihovsky (CU Boulder)
Motivated by recent experimental breakthroughs toward a realization of a solid-state Thorium-229 nuclear clock, we review the technology, basic physics motivation, and limitations of the present generation of atomic clocks. We then discuss prospects for a new generation of clocks based on an anomalous low-energy 8.4 eV nuclear transition in Th-229, with an extremely long lifetime of 641 seconds when doped into CaF crystals. To realize such solid-state nuclear clocks one must confront basic nuclear, AMO, and solid state physics questions. Key challenges are understanding and minimizing the effects of inhomogeneous broadening, associated with strains and electric field gradients due to both the Th dopants and intrinsic crystal defects.
↳ physics.atom-phcond-mat.mtrl-scicond-mat.othernucl-ex+13 citations
10
Vortex creep heating in neutron star cooling with direct Urca processes in heavy neutron stars
Yoonhak Nam · Kazuyuki Sekizawa
Old, thermally bright neutron stars imply internal heating at late times. Among candidate mechanisms, vortex creep heating (VCH) provides a robust link between spin-down and frictional dissipation in the pinned inner-crust superfluid, yet its interplay with fast DUrca cooling in massive stars remains insufficiently explored. We (i) implement VCH in our cooling code and validate it; (ii) identify the physically consistent domain where the steady-state form $L_{h} = J ∣ Ω ˙_{\infty} ∣$ applies; (iii) quantify how $(B, P_{0})$ regulate observable VCH signatures under DUrca cooling; and (iv) introduce a 3D representation that resolves degeneracies hidden in standard 2D projections. Cooling is computed with BSk24 and APR EoS, standard pairing gaps, and iron/carbon envelopes. VCH is modeled with $J ≃ 1 0^{42.9 - 43.8}$ erg s, and a quantum-creep coverage fraction $f_{Q} (t)$ diagnoses when steady-state heating is valid. We survey $B = 1 0^{10 - 13}$ G and $P_{0} = 10$ -- $570$ ms for $1.4$ and $2.0 M_{⊙}$ , and compare with a curated set of ordinary pulsars with measured $(P, P ˙)$ . Results: (1) Our implementation reproduces published VCH bands. (2) The $(B, P_{0})$ validity boundary follows magnetic-dipole spin-down, confirming consistency with $∣ Ω ˙ ∣$ . (3) DUrca+VCH maintains $T_{s}^{\infty} ≳ 1 0^{5}$ K for $B ≳ 1 0^{11 - 12}$ G up to $P_{0} \sim 1 0^{2}$ ms. (4) The 3D representation shows that sources appearing coincident in $(t, T_{s}^{\infty})$ occupy distinct $B$ -layers, removing degeneracies. VCH can substantially reshape late-time thermal states when spin-down power remains high; its observability depends chiefly on $(B, P_{0})$ rather than on mass alone. We provide a practical $(B, P_{0})$ validity map for $L_{h} = J ∣ Ω ˙_{\infty} ∣$ and advocate treating $B$ as a co-equal axis in cooling analyses. (Shortened due to the arXiv words limit.)
↳ astro-ph.HEnucl-th1 citation
11
Exploring the production of Terbium-161 in the Brazilian Multipurpose Reactor
Fernando Cozim Melges · Jhonatha Ricardo Santos · Luiz Paulo de Oliveira · Alexandre Pinho dos Santos Souza · Carlos Gabriel Santos da Silva · Iberê Souza Ribeiro Júnior · Barbara Perez Gonçalves Silva · Marco Antonio Stanojev Pereira · Frederico Antonio Genezini
The Brazilian Multipurpose Reactor (RMB) was conceived to meet national needs for radioisotope production, materials irradiation testing, and neutron beam applications. In addition to its 30~MW pool-type reactor, the RMB complex will include additional facilities for radioisotope production and related applications. $^{161} T b$ is a promising radionuclide for radiopharmaceutical therapy, offering decay properties similar to $^{177} Lu$ but with additional conversion and Auger electrons that enhance dose delivery to cancer cells. In light of this emerging radioisotope, this study explores the potential production of $^{161} T b$ in the RMB through neutron irradiation of enriched $G d_{2} O_{3}$ targets. Monte Carlo (MCNP) simulations provided detailed neutron flux distributions, which were used as input for ORIGEN calculations of isotope buildup. Assuming 10 mg targets enriched to 97.5% in $^{160} G d$ , a 40-day irradiation, and a thermal flux of $2 \cdot 1 0^{14}$ $n / c m^{2} s$ , the results indicate that $^{161} T b$ activity reaches approximately 4.5 GBq after 14 days ( $\approx 450 GB q / g$ ), in agreement with data from other research reactors. Building on prior studies that demonstrated the RMB's capability to irradiate larger targets, terabecquerel-scale yields appear feasible. These findings highlight the RMB's potential to support domestic production of emerging therapeutic radionuclides such as $^{161} T b$ . The potential for isotopic enrichment of $^{160} G d$ using the AVLIS method is also discussed.
↳ physics.ins-detnucl-exnucl-thphysics.med-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Fermi-Dirac Wigner function for massive spin-1/2 particles in local equilibrium

A Study of Tcc​(3875)+ Nature : Compact v.s. Molecule

Prospects for a Solid-State Nuclear Clock

Vortex creep heating in neutron star cooling with direct Urca processes in heavy neutron stars

Exploring the production of Terbium-161 in the Brazilian Multipurpose Reactor

Affiliations

A Study of $T_{cc} (3875)^{+}$ Nature : Compact v.s. Molecule