Twelve physics-informed machine learning models have been trained to model binding energy residuals. Our approach begins with determining the difference between measured experimental binding energies and three different mass models. Then four machine learning approaches are used to train on each energy difference. The most successful ML technique, both in interpolation and extrapolation, is the least squares boosted ensemble of trees. The best model resulting from that technique utilizes eight physical features to model the difference between experimental atomic binding energy values in AME 2012 and the Duflo Zuker mass model. This resulted in a model that fit the training data with a standard deviation of 17 keV and that has a standard deviation of 92 keV when compared all of the values in the AME 2020. The extrapolation capability of each model is discussed, and the accuracy of predicting new mass measurements has also been tested.

In this study the empirical method [V. Zagrebaev et al., Phys. Rev. C 78, 034610 (2008)] is used for calculating the evaporation residue (ER) cross section in the synthesis of superheavy nuclei (SHN). The superheavy nuclei examined in this work fall within the range $Z=112-118$. The theoretical calculations show good agreement with the experimental data. Furthermore, this model, along with an investigation of the optimal incident energy (OIE), is used to calculate the ER cross section for a hypothetical heavy system with $Z=121$. Five promising combinations are suggested for synthesis of SHN with $Z=121$: (1) ${}^{50}\mathrm{Ti}+{}^{252}\mathrm{Es}$, with the maximum ER cross section ${\sigma }_{3n}=24.5\mathrm{fb}$, at the optimal incident energy, $\mathrm{OIE}=230\mathrm{MeV}$; (2) ${}^{50}\mathrm{Ti}+{}^{254}\mathrm{Es}$, with the maximum ER cross section ${\sigma }_{3n}=11.8\mathrm{fb}$, at the optimal incident energy, $\mathrm{OIE}=229\mathrm{MeV}$; (3) ${}^{51}\mathrm{V}+{}^{251}\mathrm{Cf}$, with the maximum ER cross section ${\sigma }_{3n}=1.2\mathrm{fb}$, at the optimal incident energy, $\mathrm{OIE}=238\mathrm{MeV}$; (4) ${}^{51}\mathrm{V}+{}^{249}\mathrm{Cf}$, with the maximum ER cross section ${\sigma }_{3n}=1.0\mathrm{fb}$, at the optimal incident energy, $\mathrm{OIE}=238\mathrm{MeV}$; and (5) ${}^{54}\mathrm{Cr}+{}^{247}\mathrm{Bk}$, with the maximum ER cross section ${\sigma }_{2n}=0.9\mathrm{fb}$, at the optimal incident energy, $\mathrm{OIE}=243\mathrm{MeV}$.

We measured the nuclear dependence of the di-pion azimuthal correlation function in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer and a 5 GeV electron beam. As the nuclear-target size increases, transitioning from deuterium to carbon, iron, and lead, the correlation function broadens monotonically. Its shape exhibits a significant dependence on kinematics, including the transverse momentum of the pions and the difference in their rapidity. None of the various Monte Carlo event generators we evaluated could fully replicate the observed correlation functions and nuclear effects throughout the entire phase space. As the first study of its kind in DIS experiments, this research provides an important baseline for enhancing our understanding of the interplay between the nuclear medium and the hadronization process in these reactions.

Mean lifetime measurements of low-lying yrast positive- and negative-parity states of ${}^{150}\mathrm{Gd}$ have been performed with the ROSPHERE array using the ${}^{140}\mathrm{Ce}({}^{13}\mathrm{C},3n$) fusion-evaporation reaction and the recoil distance Doppler shift method. Precise branching ratios have been obtained from a complementary electron capture decay experiment of both the isomer and ground state of ${}^{150}\mathrm{Tb}$. Reduced $E1$, $E2$, and $E3$ transition probabilities were extracted and compared with the corresponding observables in the neighboring isotopes and isotones. The experimental data are compared to the predictions of various theoretical models: quasiparticle random phase approximation, time-dependent Hartree-Fock calculations, the quadrupole-octupole collective Hamiltonian, the mean-field mapped interacting boson model, and the triaxial projected shell model. We find that a complete description of both quadrupole and octupole collectivity, from ground and excited states, is currently lacking, and such measurements of transition strengths are crucial for constraining present and future calculations.

The Gamow-Teller strength distribution covering the entire $\beta$-decay window, up to 10.312(4) MeV, of ${}^{80g+m}\mathrm{Ga}$ was measured for the first time in photofission of ${\mathrm{UC}}_x$ induced by a 50 MeV electron beam. The new data show significant enhancement in the high-energy region with a jump structure. Simultaneously, the $\gamma$ deexciting behavior of $\beta$-populated states presents a competition between deexcitation to $2_1^{+}[{\beta }_2=0.155\left(9\right)]$ and to $2_2^{+}[{\beta }_2=0.{053}_{0.009}^{0.008})]$ in ${}^{80}\mathrm{Ge}$. To understand these data, we performed a realistic shell-model calculation and systematic analysis of $logft$ ratios between precursors' $\beta$ decay to $2_2^{+}$ and to $2_1^{+}$ of Ga isotopes. We conclude that these phenomena evidence simultaneous impacts of nuclear shell structure and collectivity on $B$(GT) distribution and therefore the half-life of the precursor.

Proton-induced fission of ${}^{238}\mathrm{U}$ was used to produce neutron-rich ${}^{117}\mathrm{Rh}$ nuclei. After separation with the IGISOL mass separator coupled to the JYFLTRAP Penning trap, the monoisotopic ${}^{117}\mathrm{Rh}$ samples were delivered to a $\beta \gamma$ coincidence spectroscopy setup, in which the $\beta$ decay of its daughter, ${}^{117}\mathrm{Pd}$ was used to investigate the levels in ${}^{117}\mathrm{Ag}$. In another experiment, the excited ${}^{117}\mathrm{Ag}$ nuclei were produced in spontaneous fission of ${}^{252}\mathrm{Cf}$ and their $\gamma$-ray emission was studied with the Gammasphere array of Compton-suppressed Ge detectors. The complementary prompt-$\gamma$ and $\beta$-decay data revealed new levels and transitions in the neutron-rich ${}^{117}\mathrm{Ag}$ nucleus. A weakly deformed band on top of the $1/2^{-}$ ground state in ${}^{117}\mathrm{Ag}$ is observed for the first time, pointing to shape coexistence of the prolate and triaxial structures in this nucleus. The newly-observed $\gamma$-ray cascades allowed for the first time to determine the positions of the $1/2^{-}$ and $7/2^{+}\beta$-decaying isomers in ${}^{117}\mathrm{Ag}$ by $\gamma$ spectroscopy methods. Our measurements clearly indicate spin $1/2^{-}$ for the ground state in ${}^{117}\mathrm{Ag}$. The internal conversion coefficients were estimated experimentally for the low-energy transitions in ${}^{117}\mathrm{Ag}$, resulting in spin-parity assignment of $9/2^{+}$ for the 175.8-keV level in ${}^{117}\mathrm{Ag}$.

A high-quality measurement of proton and $\alpha \text{−}\mathrm{particle}$ emission associated with fusion of ${}^{28,30,32}\mathrm{Si}$ with a ${}^{28}\mathrm{Si}$ target is described. Evaporation residues produced by de-excitation of the compound nucleus were identified by an energy time-of-flight measurement while emitted light-charged particles were identified using the $\mathrm{\Delta }\mathrm{E}\text{−}\mathrm{E}$ technique. Comparison of the experimentally measured charged particle multiplicities and energy spectra with the predictions of the statistical decay model code $\mathrm{GEMINI}++$ allows one to deduce interesting details of the de-excitation cascade and its dependence on neutron-excess. The impact of modifying the sequence of particle emissions on the average energy and multiplicity is examined.

Within the framework of the precluster model of $\alpha$ decay, we extend the celebrated Floquet-Volkov theory in multiphoton ionization processes to calculate the $\alpha$-decay rates of the even-even nuclear elements, specifically ${}_{52}{}^{106}\mathrm{Te}$, ${}_{84}{}^{212}\mathrm{Po}$, and ${}_{94}{}^{238}\mathrm{Pu}$, under linearly polarized intense keV x-ray laser fields. Our calculations indicate that in the x-ray regime, an intense laser field can significantly enhance the decay rates of these nuclei by several orders of magnitude with the help of multiphoton processes. The nucleus ${}_{94}{}^{238}\mathrm{Pu}$ with lower decay energies seems to be more sensitive to x-ray laser fields and shows a relatively larger enhancement, due to the fact that its relatively higher Coulomb barrier can be influenced more significantly through the multiphoton-assisted quantum tunneling. Some implications are discussed.

Ultraperipheral collisions are a source of various interesting phenomena based on photon-induced reactions. We calculate cross sections for single and any number of $n$, $p$, $\alpha$, and $\gamma$ rays in ultraperipheral heavy-ion collision for Large Hadron Collider energies. We analyze the production of a given number of neutrons relevant for a recent ALICE experiment, for $\sqrt{s_{NN}}=5.02\mathrm{TeV}$. In our approach, we include both single and multiple photon exchanges as well as the fact that not all photon energies are used in the process of equilibration of the residual nucleus. We propose a simple two-component model in which only part of photon energy $E_{\gamma }$ is changed into the excitation energy of the nucleus $(E_{\mathrm{exc}}\ne E_{\gamma })$ and compare its results with outcomes of hipse and empire codes. The role of high photon energies for small neutron multiplicities is discussed. Emission of a small number of neutrons at high photon energies seems to be crucial to understand the new ALICE data. All effects work in the desired direction, but the description of the cross section of four- and five-neutron emission cross sections from first principles is rather demanding. The estimated emission of charged particles such as protons, deuterons, and $\alpha$ is briefly discussed and confronted with very recent ALICE data, obtained with a proton zero degree calorimeter.

Fluctuations of conserved charges are a golden channel for measuring a QCD critical point in relativistic heavy-ion collisions. These fluctuations are quantified by measuring high-order cumulants of baryon-number distributions at a given centrality. Using simulated proton-number cumulants as an example, we discuss how the correlation between particle identification and centrality measurements can distort particle-number distributions. These distortions can easily create large fluctuations in high-order cumulants that might be mistaken for a critical-point signature. We show that certain measurement choices can make the analysis more or less vulnerable to these false signals. We motivate this by considering how the two-dimensional probability space of proton-number versus multiplicity is shaped by analysis choices. We then demonstrate this vulnerability with simulated $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=3.9$ GeV in UrQMD, and two toy models of detector responses to certain classes of events. We explain how an analyzer might observe a false critical signature and how to avoid doing so, even in a challenging experimental environment.

Modeling proton-deuteron interactions is particularly challenging. Due the deuteron's large size, the interaction can extend over several femtometers. The degree to which it can be modeled as a two-body problem might also be questioned. One way to study these interactions is through femtoscopic correlation measurements of particle pairs, extracting information using available theoretical models. In this work, we examine two approaches for describing proton-deuteron correlations: the Lednický-Lyuboshits formalism and full numerical solutions of the Schrödinger equation. Our results show that the differences between these methods are significant. Furthermore, we demonstrate that incorporating higher-order partial waves—particularly the p wave—is essential for accurately capturing the dynamics of proton–deuteron interactions and the full potential of the strong force.

In this study, we use the maximum likelihood estimator (MLE) to explore factorization and event-plane correlations in relativistic heavy-ion collisions. Our analyses incorporate both numerical simulations and publicly available data from the CMS Collaboration. We focus on $\mathrm{Au}+\mathrm{Au}$ collisions at 200 GeV and $\mathrm{Pb}+\mathrm{Pb}$ collisions at 2.76 TeV. The differential flows obtained for various centrality windows and momentum cuts are consistent with conventional methodologies, such as multiparticle cumulants and event-plane methods. Leveraging these findings, we proceed to undertake further analysis of flow factorization and event-plane correlations. These quantities are relevant because of their sensitivity to initial-state fluctuations. While higher-order correlators might provide different implementations of factorization ratios, the MLE is readily applied to these scenarios. Moreover, the MLE's unique capabilities allow us to compute specific correlators that are typically inaccessible by other means. As an asymptotically normal and unbiased estimator, the MLE provides a valuable alternative tool for flow and correlation analyses.

We investigate the impact of radiative and atomic exchange corrections in the two-neutrino double-beta $\left(2\nu \beta \beta \right)$ decay of ${}^{100}\mathrm{Mo}$. In the calculation of the exchange correction, the electron wave functions are obtained from a modified Dirac-Hartree-Fock-Slater self-consistent framework that ensures orthogonality between continuum and bound states. The atomic exchange correction causes a steep increase in the low-energy region of the single-electron spectrum, consistent with previous studies on $\beta$ decay, while the radiative correction primarily accounts for a 5% increase in the decay rate of ${}^{100}\mathrm{Mo}$. When combined, the radiative and exchange effects cause a leftward shift of approximately 10 keV in the maximum of the summed electron spectrum. This shift may impact current constraints on parameters governing potential new physics scenarios in $2\nu \beta \beta$ decay. The exchange and radiative corrections are introduced on top of our previous description of $2\nu \beta \beta$ decay, where we used a Taylor expansion for the lepton energy parameters within the nuclear matrix elements denominators. This approach results in multiple components for each observable, controlled by the measurable ${\xi }_{31}$ and ${\xi }_{51}$ parameters. We explore the effects of different ${\xi }_{31}$ and ${\xi }_{51}$ values, including their experimental measurements, on the total corrected spectra. These refined theoretical predictions can serve as precise inputs for double-beta decay experiments investigating standard and new physics scenarios within $2\nu \beta \beta$ decay.

An extensive study on the barrier properties and $\alpha$-decay half-lives of nuclei within the mass range $89\le Z\le 102$ is conducted using the effective Botswana-3-Yukawa (B3Y) $NN$ interaction, incorporating finite- and zero-range exchange forces. A key novelty of this work is the systematic analysis of nuclear deformation and exchange effects on half-lives along the isotopic chains. Particularly, for the finite- and zero-range exchange terms, this study investigates the appropriate strength of the Weizsäcker term, $C_s$, which represents the surface contribution to the kinetic energy density. The penetration probability of the ground-state to ground-state $\alpha$ transitions is determined using the semiclassical Wentzel-Kramers-Brillouin (WKB) approximation by considering the Bohr-Sommerfeld quantization condition. The cluster formation model (CFM) is adopted to calculate the preformation probability $S_{\alpha }$. The driving potential reveals a cold valley at the canonical magic number $N_D=126$, affirming its shell closure property, while deformed subshell closures at $N=142$ and $N=152$ are also identified. These results align with predictions from Nilsson single-particle energies. A key finding of this study is that the inclusion of nuclear deformation significantly improves the accuracy of the calculated $\alpha$-decay half-lives. The analysis also shows that the term $C_s$ directly influences the nuclear surface energy, which in turn affects the potential barrier relevant to $\alpha$ decay. Specifically, a larger value of $C_s=\frac{1}{4}$ increases the potential barrier, leading to longer half-lives, while a smaller value of $C_s=\frac{1}{36}$ reduces the barrier, resulting in shorter half-lives. Importantly, for nuclei with $Z\ge 96$, calculations involving finite-range exchange terms at $C_s=\frac{1}{36}$ yield the smallest root mean square error (RMSE), suggesting a better agreement with experimental data, and indicating its prospect for the study of superheavy nuclei.

In-beam $\gamma$-ray spectroscopy study of odd-odd nucleus ${}^{90}\mathrm{Nb}$ is reported using the heavy-ion induced fusion evaporation reaction ${}^{65}\mathrm{Cu}$(${}^{30}\mathrm{Si}, 3n2p$) at a beam energy of 120 MeV. The level scheme of ${}^{90}\mathrm{Nb}$ has been revised, with the addition of 13 new transitions and 13 new energy levels up to an excitation of 7.780 MeV and spin $19\hslash$. Shell-model calculations using the GWBXG interaction have been performed to understand the configuration and structure of the positive- and negative-parity states up to the highest observed spin. Calculations have identified multi-quasiparticle configurations with proton excitation from $Z$ = 38 for generating high spin states. Moreover, no neutron excitation was found.

In the effective field theory formalism nuclear forces are organized as a low-energy expansion. Usually the lowest order in this expansion corresponds to the nonperturbative iteration of the one-pion exchange potential and a few contact-range operators as to ensure renormalization group invariance. Here I consider an alternative expansion in which two-pion exchange becomes the lowest-order finite-range interaction and as such is expected to be iterated. A comparison of this new expansion with the standard one shows a better convergence pattern for a few selected partial waves (${}^{1}S_0, {}^{3}P_0$, and ${}^{3}S_1\text{−}{}^{3}D_1$) in two-nucleon scattering, in particular for the ${}^{1}S_0$ channel (though both expansions converge well). I briefly comment on the possible theoretical grounds for the expansion around two-pion exchange from the point of view of effective field theory.

Observations of anomalous angular correlations in electron-positron pairs produced from excited states of ${}^4\mathrm{He}, {}^8\mathrm{Be}$, and ${}^{12}\mathrm{C}$ nuclei have been suggested as being due to the creation and subsequent decay of a new light particle of mass $\sim 17\mathrm{MeV}$. In this work, we investigate the possibility that the source of the observed signals is a set of new excitation channels created by the 12-quark hidden-color Fock state within the ${}^4\mathrm{He}$ nuclear wave function dubbed the “hexadiquark.” We calculate the invariant $e^{+}{e}^{-}$ mass spectrum for the electromagnetic transition from a new excitation of ${}^4\mathrm{He}$, estimating its differential and total decay width. We find that we can fit the shape of the anomalous signal with the QCD Fock state at excitation energy $E^{*}=17.9\pm 1\mathrm{MeV}$ and a Gaussian form factor for the electromagnetic decay. We address the physical issues with the fit parameters using properties of the hexadiquark state, in particular the three weakly repulsive $6_C$ interactions of ${\mathrm{SU}\left(3\right)}_C$ between diquark pairs. Experimental tests of our model are described in detail. In light of this work, we emphasize the need for independent experimental confirmation or refutation of the ATOMKI results as well as dedicated experiments to search for the proposed new excitations of ${}^4\mathrm{He}$ and other $\alpha$-cluster nuclei.

Neutron production by the ${}^{51}\mathrm{V}(p,n){}^{51}\mathrm{Cr}$ reaction close to the reaction threshold is interesting for its pure production of neutrons at low kiloelectronvolts. In this work, for the first time, the angle-dependent neutron spectrum is measured close to the threshold, particularly at 1585 keV proton energy, only 20 keV above the reaction threshold. The experiment was performed at the MONNET facility (JRC-Geel), employing the time-of-flight technique and a thick vanadium target. The ${}^7\mathrm{Li}(p,n){}^7\mathrm{Be}$ reaction near the threshold was also measured and used as a reference and in a neutron transmission measurement for self-absorption correction. The angular-dependent energy spectra for the ${}^{51}\mathrm{V}(p,n){}^{51}\mathrm{Cr}$ have been obtained and the integrated energy spectrum is presented. Their resulting spectrum reveals a pronounce peak at (6.49 $\pm$ 0.04) keV.

A universal Wong formula is proposed with refined model parameters for a systematic description of the capture cross sections for heavy-ion fusion reactions from $\mathrm{C}+\mathrm{C}$ to $\mathrm{Ni}+\mathrm{U}$, in which the barrier parameters and the barrier distribution are determined by the entrance-channel nucleus-nucleus potential based on the Skyrme energy density functional. By introducing a constraint to the width of the barrier distribution and a pocket-depth dependent barrier radius, the capture excitation functions for a number of fusion reactions involving different nuclear structure effects are remarkably well reproduced, particularly for the reactions between light nuclei and those forming superheavy nuclei. The systematic decreasing behavior of the geometric radii with the depth of capture pocket due to the influence of deep inelastic scattering is clearly observed in the time-dependent Hartree-Fock (TDHF) calculations for superheavy systems. The predicted capture cross sections for ${}^{54}\mathrm{Cr}+{}^{238}\mathrm{U}$ at above-barrier energies are evidently smaller than the corresponding results of the more asymmetric projectile-target combination ${}^{50}\mathrm{Ti}+{}^{242}\mathrm{Pu}$ due to the shallower capture pocket in $\mathrm{Cr}+\mathrm{U}$.

The work addresses the isotopic shift of nuclear radii for the even-even ${}^{36–52}\mathrm{Ca}$ isotopes using the interacting boson model (IBM) that includes the mixing from normal and intruder configurations. We obtain a good agreement between the calculated and experimental data, particularly for the dip at ${}^{48}\mathrm{Ca}$. A direct correlation between nuclear size and electric monopole transitions is established to compute the electric monopole transition strengths, ${\rho }^2\left(E0\right)$. We further study the isotopic shift for the even-even ${}^{32–46}\mathrm{Ar}$ and ${}^{44–50}\mathrm{Ti}$ isotopes.