Particles, Volume 8, Issue 4 (December 2025) – 5 articles

The MoonRay project is carrying out a concept study of a permanent lunar cosmic-ray (CR) and gamma-ray observatory, in view of the implementation of habitats on our satellite. The idea is to build a modular telescope that will be able to overcome the limitations, in available power and weight, of the present generation of CR instruments in Low Earth Orbit, while carrying out high-energy gamma-ray observations from a vantage point at the South Pole of the Moon. An array of fully independent modules (towers), with limited individual size and mass, can provide an acceptance more than one order of magnitude larger than instruments in flight at present. The modular telescope is designed to be deployed progressively, during a series of lunar missions, while collecting meaningful scientific data at the intermediate stages of its implementation. The operational power will be made available by the facilities maintaining the lunar habitats. With a geometric factor close to 15 m²sr and about 8 times larger sensitive area than FERMI-LAT, MoonRay will be able to carry out a very rich observational program over a time span of a few decades with an energy reach of 10 PeV allowing the exploration of the CR “knee” and the observation of the Southern Sky with gamma rays well into the TeV scale. Each tower (of approximate size 20 cm × 20 cm ×100 cm) is equipped with three instruments. A combined Charge and Time-of-Flight detector (CD-ToF) can identify individual cosmic elements, leveraging on an innovative two-layered array of pixelated Low-Gain Avalanche Diode (LGAD) sensors, with sub-ns time resolution. The latter can achieve an unprecedented rejection power against backscattered radiation from the calorimeter. It is followed by a tracker, providing also photon conversion, and by a thick crystal calorimeter (55 radiation lengths, 3 proton interaction lengths at normal incidence) with an energy resolution of 30–40% (1–2%) for protons (electrons) and a proton/electron rejection in excess of 10⁵. A time resolution close to 100 ps has been obtained, with prototypal arrays of 3 mm × 3 mm LGAD pixels, in a recent test campaign carried out at CERN with Pb beam fragments. Full article

We investigate the off-shell generalized parton distributions (GPDs) and transverse momentum dependent parton distributions (TMDs) of kaons within the framework of the Nambu–Jona-Lasinio model, employing proper time regularization. Compared to the pion case, the off-shell effects in kaons are of similar magnitude, modifying the GPDs by about 10–$25\%$, which is notable. The absence of crossing symmetry leads to odd powers in the x-moments of the off-shell GPDs, giving rise to new off-shell form factors. We analyze the relations among these kaon off-shell form factors by analogy with electromagnetic form factors. Our results extend the off-shell GPDs from pions to kaons and simultaneously address the associated off-shell form factors. We also compare the off-shell and on-shell gravitational form factors of the kaon. In addition, the off-shell kaon TMD shows a stronger dependence on the momentum fraction x than its on-shell counterpart. Full article

Reliable predictions of (anti)neutrino spectra and luminosities are essential for assessing the feasibility of detecting pre-supernova neutrinos. Using the stellar evolution code MESA, we calculate the (anti)neutrino spectra and luminosities under realistic conditions of temperature, density, and electron fraction. Our study includes (anti)neutrinos produced by both thermal processes and nuclear weak-interaction reactions. By comparing the results of the thermal quasiparticle random-phase approximation with the standard technique based on the effective Q-value method, we investigate how thermal effects influence the spectra and luminosities of emitted (anti)neutrinos. Our findings show that a thermodynamically consistent treatment of Gamow–Teller transitions in hot nuclei enhances both the energy luminosity and the average energies of the emitted (anti)neutrinos. Full article

To investigate diquark correlation in baryons, the baryon spectra with different light–heavy quark combinations are calculated using Gaussian expansion method within both the naive quark model and the chiral quark model. By computing the diquark energies and separations between any two quarks in baryons, we analyze the diquark effect in the $ud$-q/Q, $us$-Q, $ss$-q/Q, and $QQ$-q/Q systems (where $q=u,d$, or s; $Q=c,b$). The results show that diquark correlations exist in baryons. In particular, for $qq$-Q and $QQ$-q systems, the same type of diquark exhibits nearly identical energy and size across different baryons. In the orbital ground states of baryons, scalar–isoscalar diquarks have lower energy and a smaller size compared to vector–isovector diquark, which qualifies them as “good diquarks”. In $QQ$-q systems, a larger mass of Q leads to a smaller diquark separation and a more pronounced diquark effect. In $qq$-Q systems, the separation between the two light quarks remains larger than that between a light and a heavy quark, indicating that the internal structure of such diquarks must be taken into account. A comparison between the naive quark model and the chiral quark model reveals that the introduction of meson exchange slightly increases the diquark size in most systems. Full article

Lutetium–Yttrium Oxyorthosilicate (LYSO) crystals and EJ-200 plastic scintillators are widely recognized fast scintillating materials, valued for their high light yield and mechanical robustness, which make them well suited for demanding applications in high-energy physics and space research. Their non-proportional light response, along with their non-linear behavior at low-energy X-rays, has been extensively investigated in previous studies, revealing potential systematic effects in existing measurements. In this work, light quenching in both scintillators is measured under charged-particle excitation. The results are interpreted using the modified Birks–Onsager model, which provides a theoretical framework for understanding the underlying quenching mechanisms, as well as a generalized logistic parametrization, offering experimentalists a useful tool to characterize the detector’s light yield and associated uncertainties. Full article