Wed·Nov 19, 2025Wednesday·November 19, 2025

1. 01*

   Search for Double Beta Decays of ${}^{134}$Xe with EXO-200 Phase II

   S. Al Kharusi🇨🇦 · G. Anton🇩🇪 · I. Badhrees🇨🇦 · P.S. Barbeau🇺🇸 · V. Belov🇷🇺 · T. Bhatta🇺🇸 · M. Breidenbach🇺🇸 · T. Brunner🇨🇦 · G.F. Cao🇨🇳 · W.R. Cen🇨🇳 · C. Chambers🇨🇦 · B. Cleveland🇨🇦 and 93 other authors

   EXO-200 was a leading double beta decay experiment consisting of a single-phase, enriched liquid xenon time projection chamber filled with an admixture of 80.672% ${}^{136}$Xe and 19.098% ${}^{134}$Xe. The detector operated at WIPP between 2010 and 2018 and was designed to search for double beta decay of ${}^{136}$Xe. Data was acquired in two phases separated by a period of detector upgrades. We report on the search for $0\nu \beta \beta$ and $2\nu \beta \beta$ decay of ${}^{134}$Xe with Phase II EXO-200 data, with median 90% C.L. exclusion sensitivity $T_{1/2}^{0\nu }\ge 3.7\times 10^{23}$ yr and $T_{1/2}^{2\nu }\ge 2.6\times 10^{21}$ yr, respectively. No statistically significant signal is observed for either decay mode. We set a world-leading lower limit on the half-life of the neutrinoless decay mode of ${}^{134}$Xe of $T_{1/2}^{0\nu }\ge 8.7\times 10^{23}$ (90% C.L.) and the second strongest constraint on the two-neutrino decay of $T_{1/2}^{2\nu }\ge 2.9\times 10^{21}$ (90% C.L.), a 3-fold improvement over the EXO-200 Phase I measurement. New constraints are also set for the $2\nu \beta \beta$ and $0\nu \beta \beta$ decays of ${}^{134}$Xe to the lowest excited state of ${}^{134}$Ba.

   nucl-exPRL(2026)·3 citations
2. 02*

   Light-Front Transverse Nucleon Charge and Magnetisation Densities

   Z.-N. Xu🇪🇸 · Z.-Q. Yao🇪🇸 · P. Cheng🇨🇳 · C. D. Roberts🇨🇳 · J. Rodriguez-Quintero🇪🇸 · J. Segovia🇪🇸

   Nucleon elastic electromagnetic form factors obtained using both the three-body and quark + fully-interacting-diquark pictures of nucleon structure are employed to calculate an array of light-front transverse densities for the proton and neutron and their dressed valence-quark constituents, viz. flavour separations of the proton and neutron results. These two complementary descriptions of nucleon structure deliver mutually compatible predictions, which match expectations based on modern parametrisations of available data, where such are available. Amongst other things, it is found that transverse-plane valence $u$- and $d$-quark Dirac radii are practically indistinguishable; but regarding kindred Pauli radii, the $d$ quark value is roughly 10% greater than that of the $u$-quark. Moreover, magnetically, the valence $d$ quark is far more active than the valence $u$ quark, probably because it has much greater orbital angular momentum. Both pictures of nucleon structure agree in predicting that, in a polarised nucleon, the transverse-plane charge densities are no longer rotationally invariant. Instead, for a $+\hat{x}$ polarised nucleon, positive charge is displaced in the $+\hat{y}$ direction, with the opposite effect for negative charge.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2026)·2 citations
3. 03*

   Cluster phenomena using few-body and Lattice QCD theories

   E. Hiyama🇯🇵 · T. Doi🇯🇵

   With the advancement of first-principles calculations for baryon-baryon interactions, it becomes possible to obtain reliable hyperon-nucleon potentials by lattice QCD simulations with the HAL QCD method. High-precision few-body methods, such as the Gaussian Expansion Method (GEM), are applicable to solve quantum few-body systems up to four- and five-body systems. By combining the HAL QCD potentials with the GEM, one can predict the level structure of novel hypernuclei prior to experimental observation. In this review, we utilize the lattice QCD $N\Xi$ potential obtained by the HAL QCD method to investigate the few-body systems $NN\Xi$ and $NNN\Xi$. Our analysis indicates that the lightest bound $\Xi$ hypernucleus is the $NNN\Xi$ system. To extract detailed information on the isospin and spin components of the $N\Xi$ interaction, we perform a four-body calculation for the $\alpha \alpha N\Xi$ system with the total isospin $T=0$ and $T=1$. We demonstrate that the level structure of this system is sensitive to the isospin and spin dependencies of the $N\Xi$ interaction. Furthermore, we propose experimental investigations to produce the $NNN\Xi$ and $\alpha \alpha N\Xi$ systems via the $(K^{-},K^{+})$ and $(K^{-},K^0)$ reactions on ${}^4$He and ${}^{10}$B targets, respectively.

   ↳ nucl-thhep-lathep-phnucl-exEPJA(2025)·2 citations
4. 04*

   Direct Neutron Detectors based on Carborane Containing Conjugated Polymers

   Aled Horner · Fani E. Taifakou · Choudhry Z. Amjad · Filip Aniés · Elizabeth George · Chris Allwork · Adrian J. Bevan🇬🇧 · Martin Heeney · Theo Kreouzis

   Thermal neutron detectors are crucial to a wide range of applications, including nuclear safety and security, cancer treatment, space research, non-destructive testing, and more. However, neutrons are notoriously difficult to capture due to their absence of charge, and only a handful of isotopes have a sufficient neutron cross-section. Meanwhile, commercially available ${}^3$He gas filled proportional counters suffer from depleting ${}^3$He feedstocks and complex device structures. In this work, we explore the potential of a carborane containing conjugated polymer ($o$CbT${}_2$-NDI) as a thermal neutron detector. The natural abundance of ${}^{10}$B in such a polymer enables intrinsic thermal neutron capture of the material, making it the first demonstration of an organic semiconductor with such capabilities. In addition, we show that thermal neutron detection can be achieved also by adding a ${}^{10}$B${}_4$C sensitiser additive to the analogous carborane-free polymer PNDI(2OD)2T, whereas unsensitised PNDI(2OD)2T control devices only respond to the fast neutron component of the radiation field. This approach allows us to disentangle the fast and thermal neutron responses of the devices tested and compare the relative performance of the two approaches to thermal neutron detection. Both the carborane containing and the ${}^{10}$B${}_4$C sensitised devices displayed enhancement due to thermal neutrons, above that of the unsensitised polymer. The detector response is found to be linear with flux up to $1.796\times 10^7$cm${}^{-2}$s${}^{-1}$ n${}_{th}\bar{v}$ and saturates at high drive biases. This study demonstrates the viability of carboranyl polymers as neutron detectors, highlights the inherent chemical tuneability of organic semiconductors, and opens the possibility of their application to a number of different low-cost, scalable, and easily processable detector technologies.

   ↳ physics.ins-detnucl-ex0 citations
5. 05*

   Deviations from the Isobaric Multiplet Mass Equation due to threshold states

   R. J. Charity🇺🇸 · J. Okołowicz🇫🇷 · M. Płoszajczak🇫🇷 · L.G. Sobotka🇺🇸 · K.W. Brown🇺🇸

   Recent studies have completed the A=16 isospin quintets for states with spin/parity J{\pi} =0+ and 2+. The dependence of their masses as a function of isospin projection shows evidence for deviations from quadratic behavior indicating isospin violation beyond the expectation from two- body forces. The deviation is most pronounced for the 2+ states. Predictions from the Shell Model Embedded in the Continuum (SMEC) allow us to explain that this isospin violation is associated with a modification of the nuclear structure due to the open-quantum-system nature of the proton- rich members of the quintet. In particular, the 0+ and 2+ states in 16Ne and the 2+ state in 16F are threshold resonances located just above a proton-decay threshold where s-wave coupling to the continuum is expected. The measured deviations of these threshold states from the quadratic behavior of the remaining members of the multiplets makes it possible to obtain information on the magnitude and the energy dependence of the continuum-coupling energy correction. Continuum coupling is also indicated for the ground state of 8C, but this time through p-wave coupling.

   ↳ nucl-thnucl-exPRL(2025)·2 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.