Wed·Dec 24, 2025Wednesday·December 24, 2025

1. 01*

   Measurement of the ambient neutron flux and spectral distribution at the Canfranc Underground Laboratory

   S.E.A. Orrigo🇪🇸 · J.L. Tain🇪🇸 · N. Mont-Geli🇪🇸 · A. Tarifeño-Saldivia🇪🇸 · L.M. Fraile🇪🇸 · M. Grieger🇩🇪 · A. Quero-Ballesteros🇪🇸 · J. Agramunt🇪🇸 · A. Algora🇪🇸 · D. Bemmerer🇩🇪 · F. Calviño🇪🇸 · G. Cortés🇪🇸 and 4 other authors

   We report on the measurement of the ambient neutron flux and its energy distribution over a broad range of neutron energies, conducted in Hall A of the Canfranc Underground Laboratory using the High Efficiency Neutron Spectrometry Array (HENSA), with a total livetime of 248 days. In particular, we obtained a thermal neutron flux of $3.4(2)\times 10^{-6}$ cm${}^{-2}$ s${}^{-1}$ and a total energy-integrated flux of $14.8(2)\times 10^{-6}$ cm${}^{-2}$ s${}^{-1}$. This work represents the first long-term measurement of the ambient neutron flux that includes a full spectral characterization across a wide energy interval (from $10^{-4}$ eV to 20 MeV), performed in an underground laboratory to date. The results are relevant for rare-event search experiments located underground, ranging from nuclear astrophysics to astroparticle physics.

   nucl-exhep-exEPJC(2026)·0 citations
2. 02*

   Isoscalar Giant Resonances in Highly-Deformed ${}^{172}$Yb

   K. Khokhar · S. Bagchi · Y. Niu🇨🇳 · C. Chen🇨🇳 · M. N. Harakeh🇳🇱 · M. Abdullah · H. Akimune · D. Das🇮🇳 · T. Doi🇯🇵 · L. M. Donaldson🇿🇦 · Y. Fujikawa · M. Fujiwara and 25 other authors

   To study the isoscalar giant resonances in a deformed case, background-free $\alpha$-particle inelastic scattering measurements using a 386 MeV $\alpha$ beam were performed on the highly-deformed ${}^{172}$Yb nucleus using the Grand Raiden spectrometer at the Research Center for Nuclear Physics (RCNP) at very forward angles, including $0^{\circ }$. The strength distributions for the isoscalar giant resonances up to $L\le 3$ were obtained using multipole decomposition analysis. The isoscalar giant monopole resonance (ISGMR) strength exhibits a splitting into two components, interpreted as the coupling of the ISGMR with the $K=0$ component of the isoscalar giant quadrupole resonance (ISGQR). A \textit{bimodal} structure is observed in the strength distribution of the isoscalar giant dipole resonance. The ISGQR strength shows an enhancement near 25 MeV, attributed to the excitation of an overtone mode, while the broadening of the main-tone peak is associated with nuclear deformation. The experimental results are well reproduced by theoretical strength distributions calculated using the quasiparticle finite amplitude method for $L\le 3$.

   nucl-exnucl-thPRC(2026)·0 citations
3. 03*

   Nuclear Responses to Two-Body External Fields Studied with the Second Random-Phase-Approximation

   Futoshi Minato🇯🇵

   This study investigates nuclear responses to two body external fields, interpreted as double phonon excitations, within the subtracted second random phase approximation (SSRPA) for 16O and 40Ca. To clarify the underlying characteristics of these modes, Hartree Fock(HF) and SSRPA with the diagonal approximation are first examined. The resulting strength distributions are nearly identical, indicating that residual interactions in the 1p1h sector contribute only weakly. This behavior contrasts with that of one body excitations, where coupling between 1p1h and 2p2h configurations is essential for generating collectivity. In the full SSRPA calculation, which incorporates the residual interaction among 2p2h configurations, the strength distributions are substantially modified. The double IS 0+ and 2+ modes show pronounced redistribution, with peaks shifted to lower energies and additional strength emerging at higher energies, whereas the double IV 1- mode shifts predominantly to higher energies due to a largely repulsive interaction, resulting in a resonance around twice the peak energy of the single giant dipole resonance. Analysis of single transition amplitudes reveals that low lying resonances are formed coherently through constructive neutron-neutron, proton-proton, and neutron-proton configurations, while high-lying resonances are dominated by neutron-proton configurations, reflecting their higher state density. These results demonstrate that double-phonon excitations cannot be described by simple folding of one-body responses; a fully microscopic treatment of 2p2h mixing, as provided by SSRPA, is essential.

   ↳ nucl-thnucl-exPRC(2026)·0 citations
4. 04*

   Glauber-theory calculations of high-energy nuclear scattering observables using variational Monte Carlo wave functions

   W. Horiuchi🇯🇵 · Y. Suzuki🇯🇵 · R.B. Wiringa🇺🇸

   Experiments using intermediate- to high-energy radioactive nuclear beams present numerous findings. Extracting important properties of physical observables relies on a firm theoretical analysis. Though Glauber theory is believed to work well, no convincing calculation has so far been done. We perform ab initio Glauber theory calculations of both elastic differential cross sections and total reaction cross sections for p+12C, 12C+12C, and 6He+12C systems. The wave functions of both 6He and 12C are generated by variational Monte Carlo calculations with spatial and spin-isospin correlations induced by realistic two- and three-nucleon potentials. Glauber's phase-shift function is computed by Monte Carlo integration up to all orders of nucleon-nucleon multiple scatterings. We show an excellent performance of the Glauber description to the selected data on the above systems. We also find that the cumulant expansion of the phase-shift function converges rapidly up to the second order for the above systems. This finding will open up interesting applications for the analysis of high-energy nuclear experiments.

   ↳ nucl-thnucl-exPRL(2026)·5 citations
5. 05*

   Exploring quark mass dependent three-nucleon forces in medium-mass nuclei

   Urban Vernik🇩🇪 · Kai Hebeler🇩🇪 · Achim Schwenk🇩🇪

   Recently, new quark mass dependent three-nucleon (3N) forces have been identified, whose contributions in nuclear matter exceed expectations of Weinberg power-counting arguments. In this work, we investigate the impact of the most dominant new interaction term, characterized by the coupling $F_2$, in ab initio calculations of medium-mass nuclei. For this, we combine the new $F_2$ interaction with established 3N interactions up to next-to-next-to-leading order (N${}^2$LO) and next-to-next-to-next-to-leading order (N${}^3$LO) in chiral effective field theory. We explore two fit strategies for the low-energy couplings. The first is based only on few-body observables, while the second also incorporates information from ${}^{16}$O. Generally, we find that the $F_2$ interaction has a significant impact on energies and radii, however mainly due to changes in the short-range couplings. Overall, we do not find systematic improvements in the reproduction of medium-mass nuclei when the additional $F_2$ interaction is included.

   ↳ nucl-thnucl-exPRC(2026)·2 citations
6. 06*

   A possible solution to the gallium anomaly moving beyond the leptonic wave function factorization

   M. Cadeddu🇮🇹 · N. Cargioli🇮🇹 · F. Dordei🇮🇹 · L. Ferro🇮🇹 · C. Giunti🇮🇹 · M. Pitzalis🇮🇹

   For over thirty years, a $\sim 20\%$ deficit, now exceeding $5\sigma$, has persisted between measured and predicted neutrino capture rates on ${}^{71}$Ga, as observed in radioactive source experiments (namely GALLEX, SAGE, and more recently BEST) using ${}^{51}$Cr and ${}^{37}$Ar. This long-standing discrepancy, referred to as the gallium anomaly, has posed a significant challenge to our understanding of both experimental methods and theoretical predictions. In this work, we revisit the theoretical calculation of the neutrino capture cross-section by moving beyond the standard treatment of the leptonic wave functions, revealing limitations in the commonly used factorization approach based on the detailed balance principle. Incorporating phenomenologically constrained Gamow-Teller transition densities, able to correctly reproduce the precisely measured half-life of ${}^{71}\text{Ge}$, we find that the revised cross-section can be significantly reduced, potentially resolving the gallium anomaly without invoking new physics.

   ↳ hep-phhep-exnucl-exnucl-th3 citations
7. 07*

   Benchmarking Hadronic Models in Geant4 for Detector Simulations

   S.D. Savenkov (1 and 2)🇷🇺 · A.O. Svetlichnyi (1 and 2)🇷🇺 · I.A. Pshenichnov (1 and 2) ((1) Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia, (2) Moscow Institute of Physics and Technology, Dolgoprudny, Russia)🇷🇺

   The construction of modern detectors used in high-energy physics experiments is typically guided by modeling with the Geant4 toolkit to evaluate detector performance in terms of geometrical acceptance and detection efficiency. Several hadronic models are available in Geant4 for modeling nuclear reactions induced by fast nucleons. It is shown that they result in different multiplicity and charge distributions of secondary particles and nuclear fragments. The impact of these differences on modeling the Highly-Granular Neutron Detector (HGND) prototype for the BM@N experiment at Nuclotron-based Ion Collider fAcility (NICA) is evaluated.

   ↳ physics.ins-dethep-exnucl-ex0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.