We report nuclear charge radii for the isotopes $^{104-134}$Sn, measured using two different collinear laser spectroscopy techniques at ISOLDE-CERN. These measurements clarify the archlike trend in charge radii along the isotopic chain and reveal an odd-even staggering that is more pronounced near the $N=50$ and $N=82$ shell closures. The observed local trends are well described by both nuclear density functional theory and valence space in-medium similarity renormalization group calculations. Both theories predict appreciable contributions from beyond-mean-field correlations to the charge radii of the neutron-deficient tin isotopes. The models fall short, however, of reproducing the magnitude of the known $B(E2)$ transition probabilities, highlighting the remaining challenges in achieving a unified description of both ground-state properties and collective phenomena.

The semi-magic $^{110-122}\mathrm{Sn}$ isotopes display signs of shape coexistence in their excited $0^+$ states, which, in contrast to the spherical $0^+$ ground states, are deformed. This paper investigates the nuclear structure of $^{114}\mathrm{Sn}$ using the competing $\beta^+$ decay and electron capture of a radioactive beam of $^{114}\mathrm{Sb}$ produced at the TRIUMF-ISAC facility using the GRIFFIN spectrometer. This study will allow for an in-depth understanding of the excited $0^+$ states in $^{114}\mathrm{Sn}$, by focusing on their decay patterns. In the present experiment, transitions at 856.2-keV and 1405.0-keV, which were observed in an earlier $\beta^+$ decay study but not placed in the $^{114}\mathrm{Sn}$ level scheme, have been assigned to the level scheme in connection to the $0^+_3$ level at 2156.0-keV. Properly assigning these transitions refines the level scheme and enhances our understanding of the nuclear structure in $^{114}\mathrm{Sn}$.

We present results from the Jefferson Lab E08-014 experiment, investigating short-range correlations (SRC) through measurements of absolute inclusive quasi-elastic cross sections and their ratios. This study utilized 3.356 GeV electrons scattered off targets including $^2$H, $^3$He, $^4$He, $^{12}$C, $^{40}$Ca, and $^{48}$Ca, at modest momentum transfers ($1.3 < Q^2 \leq 2$ GeV$^2$). Kinematics were selected to enhance the cross-section contribution from high-momentum nucleons originating from the strongly interacting, short-distance components of two-nucleon SRCs (2N-SRCs), known to exhibit a universal structure across both light and heavy nuclei.We analyzed the A/$^2$H ratio within the region dominated by 2N-SRCs to characterize the nuclear dependence of SRC contributions across various nuclei. Additionally, the A/$^3$He ratio was examined at kinematics sensitive to nucleons with even higher momentum, aiming to identify signals indicative of three-nucleon SRCs (3N-SRCs). The traditional analysis method in the expected 3N-SRC region ($x > 2$) did not yield a clear plateau; instead, the data diverged from the predicted 3N-SRC behavior as momentum transfer increased. However, when analyzed in terms of the struck nucleon's light-cone momentum, the data exhibited the opposite trend, progressively approaching the predicted 3N-SRC plateau. These observations suggest that future measurements at higher energies may facilitate a definitive isolation and identification of 3N-SRCs.

Neutrinoless double-beta decay of nuclei represents one of the most promising methods for uncovering physics beyond the Standard Model. In this context, $^{76}$Ge stands out as a particularly attractive candidate, as it can serve as an intrinsic component in semiconductor detectors. If the neutrinoless process occurs in $^{76}$Ge, its signature would appear as a distinct peak at the $Q$ value of 2039 keV. A neutron activation measurement was performed on a germanium sample isotopically enriched in $^{76}$Ge at the DT neutron generator of TU Dresden. The measurement confirmed the presence of $\gamma$ rays with energies of 2033.1$\pm$0.5 keV, 2035.5$\pm$0.4 keV, and 2040.22$\pm$0.26 keV originating from the decays of $^{74}$Ga and $^{76}$Ga. These $\gamma$ rays lie in close proximity to the expected neutrinoless double-beta decay signal of $^{76}$Ge.

We report the measurement of the parity-violating asymmetry in the N to $\Delta$ transition via the $e^- + p \rightarrow e^- + \Delta ^+$ reaction at two different kinematic points with low four-momentum transfer Q$^2$. Measurements were made with incident electron beam energies of 0.877 and 1.16 GeV, corresponding to $Q^2$ values of 0.0111 and 0.0208 (GeV/c)$^2$, respectively. These measurements put constraints on a low-energy constant in the weak Lagrangian, $d_\Delta$, corresponding to a parity-violating electric-dipole transition matrix element. This matrix element has been shown to be large in the strangeness-changing channel, via weak hyperon decays such as $\Sigma ^+ \rightarrow p\gamma$. The measurements reported here constrain $d_\Delta$ in the strangeness-conserving channel. The final asymmetries were -0.65 +- 1.00 (stat.) +- 1.02 (syst) ppm (parts per million) for 0.877 GeV and -3.59 +- 0.82 (stat.) +- 1.33 (syst.} ppm for 1.16 GeV. With these results we deduce a small value for $d_\Delta$, consistent with zero, in the strangeness-conserving channel, in contrast to the large value for $d_\Delta$ previously reported in the strangeness-changing channel.

CRES is a technique for precision measurements of kinetic energies of charged particles, pioneered by the Project 8 experiment to measure the neutrino mass using the tritium endpoint method. It was recently employed for the first time to measure the molecular tritium spectrum and place a limit on the neutrino mass using a cm$^3$-scale detector. Future direct neutrino mass experiments are developing the technique to overcome the systematic and statistical limitations of current detectors. This paper describes one such approach, namely the use of antenna arrays for CRES in free space. Phenomenology, detector design, simulation, and performance estimates are discussed, culminating with an example design with a projected sensitivity of $m_{\beta} < 0.04 \ \mathrm{eV}/c^2$. Prototype antenna array measurements are also shown for a demonstrator-scale setup as a benchmark for the simulation. By consolidating these results, this paper serves as a comprehensive reference for the development and performance of antenna arrays for CRES.

There is growing evidence that high-energy scattering processes involving nuclei can offer unique insights into the many-body correlations present in nuclear ground states, in particular those of deformed nuclei. These processes involve, for instance, the collective anisotropic flows in heavy-ion collisions, or the diffractive production of vector mesons in photo-nuclear ($\gamma A$) interactions. In this paper, we use a classical approximation and simple analytical models in order to exhibit characteristic and universal features of ground-state correlation functions that result from the presence of a deformed intrinsic state. In the case of a small axial quadrupole deformation, we show that the random rotation of the intrinsic density of the nucleus leads to a specific quadrupole modulation of the lab-frame two-body density as a function of the relative azimuthal angle. As a phenomenological, albeit academic application, we analyze the diffractive production of vector mesons in high-energy $\gamma+^8$Be collisions. This demonstrates with the simplest deformed nucleus how the two-body correlations impact the $|t|$ dependence of the incoherent cross sections.

There are evidences that the properties of the hadrons are modified in a nuclear medium. Information about the medium modifications of the internal structure of the hadrons are fundamental for the study of dense nuclear matter and high energy processes including heavy-ion and nucleus-nucleus collisions. At the moment, however, the empirical information about the medium modifications of the hadrons is limited, therefore, theoretical studies are essential for the progress in the field. In the present work we review theoretical studies of the electromagnetic and axial form factors of octet baryons in symmetric nuclear matter. The calculations are based on a model that takes into account the degrees of freedom revealed on experimental studies of the low and intermediate square transfer momentum $q^2=-Q^2$: valence quarks and meson cloud excitations of the baryon cores. The formalism combines a covariant constituent quark model, developed for the free space (vacuum) with the quark-meson coupling model for the extension to the nuclear medium. We conclude that the nuclear medium modifies the baryon properties differently according to the flavor content of the baryons and the medium density. The effects of the medium increase with the density, and are stronger (quenched or enhanced) for light baryons than for heavy baryons. In particular, the in-medium neutrino-nucleon and antineutrino-nucleon cross sections are reduced compared to the values in free space. The proposed formalism can be extended to densities above the normal nuclear density and applied to neutrino-hyperon and antineutrino-hyperon scattering in dense nuclear matter.

J-PARC E05 reported recently a hint of a $\Xi^--{^{11}{\rm B}}$ nuclear state in the ${^{12}}{\rm C}(K^-,K^+){^{12}_{\Xi}}{\rm Be}$ spectrum, bound by $B_{\Xi^-}=8.9\pm 1.4 {^{+3.8}_{-3.1}}$ MeV. Using a density-dependent $\Xi$-nuclear optical potential $V_{\rm opt}^{\Xi}(\rho)$ we explore to what extent a $\Xi^-_{1s}$ assignment of this nuclear state is compatible with $\Xi^-_{1s}$ and $\Xi^-_{1p}$ nuclear-state interpretations of $\Xi^-$ capture events in light emulsion-nuclei experiments. We find that the only acceptable $\Xi^-_{1s}$ assignment at present, barring an abnormally strong repulsive $\rho^2$ component of $V_{\rm opt}^{\Xi}(\rho)$, is that for the $\Xi^--{^{11}{\rm B}}$ signal. This finding supports reassigning $\Xi^-$ capture events in $^{14}$N, originally assigned as $\Xi^-_{1s}-{^{14}{\rm N}}$ nuclear states, to $\Xi^0_{1p}-{^{14}{\rm C}}$ nuclear states. The depth of $V_{\rm opt}^{\Xi}(\rho)$ at nuclear-matter density $\rho_0=0.17$ fm$^{-3}$ is then $V_{\rm opt}^{\Xi}(\rho_0)\sim 21$ MeV (attractive).

The joint work of European target laboratories in the ChETEC-INFRA project is presented, to face the new experimental challenges of nuclear astrophysics. In particular, results are presented on innovative targets of 12,13C, 16O, and 19F that were produced, characterized, and, in some cases, tested under beam irradiation. STAR (Solid Targets for Astrophysics Research) is already acting to increase collaboration among laboratories, to achieve shared protocols for target production, and to offer a characterization service to the entire nuclear astrophysics community.

It is well-known that the momentum spectra of particles confined to finite spatial volumes deviate from the continuous spectra used for unconfined particles. In this article, we consider real scalar particles confined to finite volumes with periodic boundary conditions, such that the particles' spectra are discrete. We directly compute the density matrices describing the decay processes $\phi \to \varphi^2$ and $\phi \to \varphi\chi\nu$, and subsequently derive expressions for the decay probabilities both for confined and unconfined particles. The latter decay process is used as a rough toy model for a neutron decaying into a proton, an electron, and an anti-electron neutrino. We propose that finite volume effects can have an impact on the outcomes of experiments measuring the neutron lifetime. In addition, our findings at the toy model level suggest that taking into account possible initial correlations between neutrons and their daughter particles might be relevant as well.

In rare events experiments, such as those devoted to the direct search of dark matter, a precise knowledge of the environmental gamma and neutron backgrounds is crucial for reaching the design experiment sensitivity. The neutron component is often poorly known due to the lack of a scalable detector technology for the precise measurement of low-flux neutron spectra. Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG) is a newly developed, high-density scintillating crystal with a high gadolinium content, which could allow to exploit the high $(n,\gamma)$ cross section of $^{155}$Gd and $^{157}$Gd for neutron measurements in underground environments. GAGG crystals feature a high scintillation light yield, good timing performance, and the capability of particle identification via pulse-shape discrimination. In a low-background environment, the distinctive signature produced by neutron capture on gadolinium, namely a $\beta/\gamma$ cascade releasing up to 9 MeV of total energy, and the efficient particle identification provided by GAGG could yield a background-free neutron capture signal. In this work, we present the characterization of a first GAGG detector prototype in terms of particle discrimination performance, intrinsic radioactive contamination, and neutron response.

The MORA experimental setup is designed to measure the triple-correlation D parameter in nuclear beta decay. The D coefficient is sensitive to possible violations of time-reversal invariance. The experimental configuration consists of a transparent Paul trap surrounded by a detection setup with alternating beta and recoil-ion detectors. The octagonal symmetry of the detection setup optimizes the sensitivity of positron-recoil-ion coincidence rates to the D correlation, while reducing systematic effects. MORA utilizes an innovative in-trap laser polarization technique. The design and performance of the ion trap, associated beamline elements, lasers and beta and recoil-ion detectors, are presented. Recent progress towards the polarization proof-of-principle is described.

Processes that violate baryon number, most notably proton decay and $n\bar n$ transitions, are promising probes of physics beyond the Standard Model (BSM) needed to understand the lack of antimatter in the Universe. To interpret current and forthcoming experimental limits, theory input from nuclear matrix elements to UV complete models enters. Thus, an interplay of experiment, effective field theory, lattice QCD, and BSM model building is required to develop strategies to accurately extract information from current and future data and maximize the impact and sensitivity of next-generation experiments. Here, we briefly summarize the main results and discussions from the workshop "INT-25-91W: Baryon Number Violation: From Nuclear Matrix Elements to BSM Physics," held at the Institute for Nuclear Theory, University of Washington, Seattle, WA, January 13-17, 2025.

We present a physics-embedded Bayesian neural network (PE-BNN) framework that integrates fission product yields (FPYs) with prior nuclear physics knowledge to predict energy-dependent FPY data with fine structure. By incorporating an energy-independent phenomenological shell factor as a single input feature, the PE-BNN captures both fine structures and global energy trends. The combination of this physics-informed input with hyperparameter optimization via the Watanabe-Akaike Information Criterion (WAIC) significantly enhances predictive performance. Our results demonstrate that the PE-BNN framework is well-suited for target observables with systematic features that can be embedded as model inputs, achieving close agreement with known shell effects and prompt neutron multiplicities.

Within the relativistic mean field framework, in an extended Thomas-Fermi approximation, we calculate the binding energy and charge distribution radius for the latest superheavy nuclei, synthesised in various laboratories, with atomic numbers $Z = 110-118$. The binding energy and radii are compared with the results obtained from relativistic Hartree calculations along with the experimental data, wherever available, to check the reliability of the methods. The calculations are extended to estimate the giant monopole resonances to understand the collective vibration of the nucleons for such superheavy nuclei. The giant monopole resonances obtained from scaling calculations are compared with the constraint computations. Furthermore, the results are compared with other known methods, such as the relativistic Random Phase Approximation (RPA) and time-dependent mean field calculations, along with some known lighter nuclei, specifically Zr isotopes (N = 42-86) and O isotopes (N = 10-36). Finally, the nuclear compressibility of the superheavy nuclei is predicted from the energy obtained in the breathing mode.

The harmonic flow coefficients of light nuclei and hypernuclei in Au+Au collisions at $\sqrt{s_\mathrm{NN}}=3$ GeV are investigated using the Ultra-relativistic Quantum Molecular Dynamics transport model. For the Equation-of-State we employ a density and momentum dependent potential from the Chiral-Mean-Field model. Light nuclei and hypernuclei production is described at kinetic freeze-out via a coalescence mechanism or with a statistical multi-fragmentation calculation. The directed flow $v_1$ of p, d, t, $^3$He, $^4$He as well as the $\Lambda$, $^3_\Lambda$H and $^4_\Lambda$H is shown to approximately scale with mass number $A$ of the light cluster in both calculations. This is in agreement with the experimental results for the directed flow measured by STAR. Predictions for the directed and elliptic flow of (hyper)nuclei at further RHIC-FXT and FAIR energies show that the scaling properties should improve as the beam energy is increased.