We report the measurement of $x_B$ scaling in $(e,e^{\prime }p)$ cross-section ratios off nuclei relative to deuterium at large missing momentum of $350\le p_{\mathrm{miss}}\le 600 \mathrm{MeV}/c$. The observed scaling extends over a kinematic range of $0.7\le x_B\le 1.8$, which is significantly wider than $1.4\le x_B\le 1.8$ previously observed for inclusive $(e,e^{\prime })$ cross-section ratios. The $x_B$-integrated cross-section ratios become constant (i.e., scale) beginning at $p_{\mathrm{miss}}\approx k_F$, the nuclear Fermi momentum. Comparing with theoretical calculations we find good agreement with generalized contact formalism calculations for high missing momentum ($>375 \mathrm{MeV}/c$), suggesting the observed scaling results from interacting with nucleons in short-range correlated (SRC) pairs. For low missing momenta, mean-field calculations show good agreement with the data for $p_{\mathrm{miss}}<k_F$, and suggest a potential non-negligible contribution to the measured cross-section ratios from scattering off single, uncorrelated, nucleons up to $p_{\mathrm{miss}}\approx 350 \mathrm{MeV}/c$. Therefore, SRCs become dominant in nuclei at $p_{\mathrm{miss}}\approx 350 \mathrm{MeV}/c$, well above the nuclear Fermi Surface of $k_F\approx 250 \mathrm{MeV}/c$.

In the low-energy region, efforts have been made to understand the fusion mechanism of non-$\alpha$-cluster projectiles, such as ${}^{14}\mathrm{N}$ and ${}^{19}\mathrm{F}$. However, analyzing the contributing degrees of freedom has been hard in such reactions due to the lack of experimental data. This article reports the measurement of residual cross sections from the ${}^{14}\mathrm{N}$ induced reaction on ${}^{93}\mathrm{Nb}$ within the energy range of 42–59 MeV. The residues ${}^{104}\mathrm{Cd}$, ${}^{104}\mathrm{Ag}$, ${}^{103}\mathrm{Ag}$, ${}^{101}\mathrm{Pd}$, and ${}^{101m}\mathrm{Rh}$ produced during the reaction were identified using $\gamma$-ray spectroscopy. The measured excitation functions have been analyzed with the equilibrium and pre-equilibrium mechanism-based model codes to understand the associated reaction mechanism. A revision of intensity corresponding to the 118.72 keV $\gamma$ ray of ${}^{103}\mathrm{Ag}$ has also been proposed in this article.

The production of prompt ${\mathrm{\Lambda }}_c^{+}$ baryons has been measured at midrapidity in the transverse momentum interval $0<p_T<1 \text{GeV}/c$ for the first time, in $pp$ and $p$–Pb collisions at a center-of-mass energy per nucleon-nucleon collision $\sqrt{s_{NN}}=5.02\text{TeV}$. The measurement was performed in the decay channel ${\mathrm{\Lambda }}_c^{+}\to p{K}_S^0$ by applying new decay reconstruction techniques using a Kalman-Filter vertexing algorithm and adopting a machine-learning approach for the candidate selection. The $p_T$-integrated ${\mathrm{\Lambda }}_c^{+}$ production cross sections in both collision systems were determined and used along with the measured yields in Pb–Pb collisions to compute the $p_T$-integrated nuclear modification factors $R_{p\mathrm{Pb}}$ and $R_{AA}$ of ${\mathrm{\Lambda }}_c^{+}$ baryons, which are compared to model calculations that consider nuclear modification of the parton distribution functions. The ${\mathrm{\Lambda }}_c^{+}/D^0$ baryon-to-meson yield ratio is reported for $pp$ and $p$–Pb collisions. Comparisons with models that include modified hadronization processes are presented, and the implications of the results on the understanding of charm hadronization in hadronic collisions are discussed. A significant ($3.7\sigma$) modification of the mean transverse momentum of ${\mathrm{\Lambda }}_c^{+}$ baryons is seen in $p$–Pb collisions with respect to $pp$ collisions, while the $p_T$-integrated ${\mathrm{\Lambda }}_c^{+}/D^0$ yield ratio was found to be consistent between the two collision systems within the uncertainties.

In ultraperipheral collisions (UPCs) of relativistic nuclei without overlap of nuclear densities, the two nuclei are excited by the Lorentz-contracted Coulomb fields of their collision partners. In these UPCs, the typical nuclear excitation energy is below a few tens of MeV, and a small number of nucleons are emitted in electromagnetic dissociation (EMD) of primary nuclei, in contrast to complete nuclear fragmentation in hadronic interactions. The cross sections of emission of given numbers of neutrons in UPCs of ${}^{208}\mathrm{Pb}$ nuclei at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV were measured with the neutron zero degree calorimeters (ZDCs) of the ALICE detector at the LHC, exploiting a similar technique to that used in previous studies performed at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV. In addition, the cross sections for the exclusive emission of one, two, three, four, and five forward neutrons in the EMD, not accompanied by the emission of forward protons, and thus mostly corresponding to the production of ${}^{207,206,205,204,203}\mathrm{Pb}$, respectively, were measured for the first time. The predictions from the available models describe the measured cross sections well. These cross sections can be used for evaluating the impact of secondary nuclei on the LHC components, in particular, on superconducting magnets, and also provide useful input for the design of the Future Circular Collider (FCC-hh).

The search for the smallest quark-gluon plasma (QGP) droplets in nature has motivated recent small collisions system programs at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC). Unambiguous identification of jet quenching due to final-state interactions is key to confirming quark-gluon plasma (QGP) formation in these reactions. We compute the nuclear modification factors $R_{AA}$ and $R_{p\left(d\right)A}$ of charged hadrons and heavy flavor mesons in large (Au-Au, Xe-Xe, Pb-Pb) and small ($d\text{−}\mathrm{Au}$, $p\text{−}\mathrm{Pb}$, O-O) colliding systems, respectively. Our results include the Cronin effect and initial-state parton energy loss in cold nuclear matter. In the final state, hard partons undergo collisional energy loss and branching that was recently derived using soft-collinear-effective-theory with Glauber gluons (${\mathrm{SCET}}_{\mathrm{G}}$). In large colliding systems, medium-modified quantum chromodynamics evolution of the fragmentation functions dominates the nuclear correction. As the system size decreases, we find that cold nuclear matter effects, collisional energy loss, and QGP-induced radiations can become equally important. A systematic scan over the medium size and mass or flavor dependence of $R_{AA}$ provides the opportunity to separate these individual contributions and identify QGP signatures in small systems. Predictions for $R_{AA}^h$, $R_{AA}^D$, $R_{AA}^B$ in O-O collisions at $\sqrt{s}=0.2$ and 7 TeV are presented with and without the formation of a QGP and contrasted with the corresponding $R_{p\left(d\right)A}$ calculations. Single-hadron measurements at RHIC and the LHC will not only test the O-O predictions for both light and heavy flavor production but also shed light on the possibly very different dynamics of $p\text{−}A$ and $A\text{−}A$ reactions at similar soft particle production multiplicities.

We investigate whether a neural network approach can reproduce and predict the electron-nucleus cross sections in the kinematical domain of present and future accelerator-based neutrino oscillation experiments. For this purpose, we consider the large amount of data available to the community via the University of Virginia's Quasielastic Electron Nucleus Scattering Archive and use a residual, fully connected feedforward neural network. We illustrate the training performances of the neural network by comparing its results with experimental data for the electron double-differential cross section on carbon. The agreement between predictions and data is remarkable from quasielastic to deep-inelastic scattering. To test the predicting power of the neural network we consider the numerous kinematical conditions for which experimental cross sections on calcium are available. Furthermore, we show the predictions of the electron-scattering cross sections on oxygen, argon, and titanium: Nuclei of particular interest in the context of present and future accelerator-based neutrino oscillation programs. The agreement between these predictions and the data is comparable to the one of other theoretical models commonly used to calculate electron and neutrino cross sections, such as SuSAv2 and GiBUU. Results obtained with genie, a Monte Carlo event generator, are also discussed for comparison. The good performances obtained with our neural network suggest that neural networks could be exploited for theoretical and experimental investigations of electron- and neutrino-nucleus scattering.

We consider the capture of a muon on a deuteron. An uncertainty analysis of the dominant channels is important for a careful analysis of forthcoming experimental data. We quantify the theoretical uncertainties of chiral effective-field-theory predictions of the muon-deuteron capture rate from the relevant neutron-neutron partial wave channels in the final state. We study the dependence on the cutoff used to regularize the interactions, low-energy constants calibrated using different fitting data and strategies, and truncation of the effective-field-theory expansion of the currents. Combining these approaches gives as an estimate of ${\mathrm{\Gamma }}_{\mu d}^{1/2}=399.1\pm 7.6\pm 4.4{\mathrm{s}}^{-1}$ for capture from the atomic doublet state, and ${\mathrm{\Gamma }}_{\mu d}^{3/2}=12.31\pm 0.47\pm 0.04{\mathrm{s}}^{-1}$ for capture from the quartet state and the first and second uncertainties given here are due to the effective field theory truncation error and the uncertainty in the axial radius, respectively.

${}^{26}\mathrm{Al}$ with a half-life of $7.17\times {10}^5$ years is one of the most significant nuclides in $\gamma$-ray astronomy and presolar grains of meteorites. Its main production mechanism in the $\mathrm{H}$-burning MgAl cycle is the ${}^{25}\mathrm{Mg}(p,\gamma ){}^{26}\mathrm{Al}$ reaction. In the temperature region of 0.05–0.3 GK of astrophysical interest, the astrophysical ${}^{25}\mathrm{Mg}(p,\gamma ){}^{26}\mathrm{Al}$ reaction rate is dominated by the resonant capture of several low-energy resonances. In this work, we report the results of a complete experimental investigation of the $E_{\mathrm{c}.\mathrm{m}.}=92$, 130, and 189 keV resonances in the ${}^{25}\mathrm{Mg}(p,\gamma ){}^{26}\mathrm{Al}$ reaction with the Jinping Underground Nuclear Astrophysics Experimental Facility. The updated thermonuclear ${}^{25}\mathrm{Mg}(p,\gamma ){}^{26}\mathrm{Al}$ reaction rate is (32–39)% higher than that obtained at the Laboratory for Underground Nuclear Astrophysics around 0.07–0.09 GK, mainly due to the 32% enhancement of the 92-keV resonance strength. The astrophysical impact of our new rate on the ${}^{26}\mathrm{Al}$ yield in a 5 ${\mathrm{M}}_{\odot }$ low-metallicity asymptotic giant branch star is investigated, in which an increase of (45–79)% in the ${}^{26}\mathrm{Al}$ yield is found by adopting our new ${}^{25}\mathrm{Mg}(p,\gamma ){}^{26}\mathrm{Al}$ rates.

Low energy, low rate experiments, such as searches for neutrinoless double $\beta$ decay and dark matter, require unprecedentedly low levels of background in order to deliver their full science potential. ${}^{210}\mathrm{Po}$ driven, neutron induced background, caused by nuclear $(\alpha ,n)$ reactions on low-$Z$ materials, direct background contributions of the ${}^{210}\mathrm{Po}\alpha$ radiation and desorption of the ${}^{210}\mathrm{Pb}$ progeny ${}^{210}\mathrm{Bi}$ from surfaces into the detector medium are of particular of concern. These backgrounds depend on details of the components' exposure to radon-loaded laboratory air and, thus, their handling history. The attachment rates of airborne radon progeny to surfaces, needed for the estimation of these background rates, are poorly understood. This article reports the results of a campaign comprising of more than 1200 attachment measurements, performed for nine different materials. Correlations of the attachment with environmental parameters such as air exchange rate, electrical surface potential, temperature, atmospheric pressure, and relative humidity have been studied and found to be significant only in case of the first two. Attachment modeling, using the Jacobi model, is compared to data.

We apply a three-dimensional (3D) approach to investigate the quasistationary states of well-deformed $\alpha$ emitters. With a splitting of the anisotropic 3D potential into internal and external parts at a separation surface, the 3D $\alpha$-cluster decay width is determined by the initial wave function of a true bound state of an anisotropic harmonic oscillator potential and a nonresonance scattering wave function of Coulomb potential. Substantial difference between the one-dimensional (1D) and 3D decay width is found for typical $\alpha$ emitters with large quadrupole and hexadecapole deformations.

We report systematic measurements of dielectron ($e^{+}{e}^{-}$) invariant-mass $M_{ee}$ spectra at midrapidity in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}$ = 27, 39, and 62.4 GeV taken with the STAR detector at the Relativistic Heavy Ion Collider. For all energies studied, a significant excess yield of dielectrons is observed in the low-mass region ($0.40<M_{ee}<0.75 \mathrm{MeV}/c^2$) compared to hadronic cocktail simulations at freeze-out. Models that include an in-medium broadening of the $\rho$-meson spectral function consistently describe the observed excess. In addition, we report acceptance-corrected dielectron-excess spectra for $\mathrm{Au}+\mathrm{Au}$ collisions at midrapidity ($|y_{ee}|<$ 1) in the 0–80% centrality bin for each collision energy. The integrated excess yields for $0.4<M_{ee}<0.75\text{GeV}/c^2$, normalized by the charged particle multiplicity at midrapidity, are compared with previously published measurements for $\mathrm{Au}+\mathrm{Au}$ at $\sqrt{s_{NN}\phantom{{}^1}}$ = 19.6 and 200 GeV. Models that include an in-medium broadening of the $\rho$-meson spectral function consistently describe the observed excess. The normalized excess yields in the low-mass region show no significant collision energy dependence. The data, however, are consistent with model calculations that demonstrate a modest energy dependence.

Background: Muon captures on nuclei have provided us with plenty of knowledge of nuclear properties. Recently, this reaction attracts attention in electronics, because charged particle emissions following muon capture on silicon become to trigger non-negligible soft errors in memory devices.

Purpose: To date, there is no theoretical framework based on the nuclear structure that describes a muon capture reaction followed by particle emissions comprehensively. The purpose of this work is to develop a new method that considers the nuclear many-body correlation for the accurate understanding of the soft errors in memory devices.

Method: We combined the second Tamm-Dancoff approximation that is used to estimate muon capture rates with the two-component exciton model, the model describing particle emission from the pre-equilibrium state. For particle evaporation from the compound state, the Hauser-Feshbach statistical models were applied. We chose ${}^{28}\mathrm{Si}$ and ${}^{40}\mathrm{Ca}$ to check the performance of the framework.

Result: We paid attention to the muon capture rates, the particle emission spectra, and the multiplicities that have a close interrelation with each other. We found that the nuclear many-body correlations including two-particle two-hole excitations is a key to explaining them simultaneously.

Conclusion: The present study showed that the combination of the microscopic approach of muon capture and the two-component exciton model of particle emission is an effective tool to describe particle emission following the muon captures, giving the nuclear structure information additionally. For a finer understanding of particle emission following muon capture and a validation of the present framework, further experimental studies on particle emission spectra are highly expected.

Two-particle transverse momentum differential correlators, recently measured in Pb-Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms and infer transport properties, such as the ratio of shear viscosity to entropy density, of the medium created in Pb-Pb collisions. The longitudinal long-range correlations and the large azimuthal anisotropy measured at low transverse momenta in small collision systems, namely $pp$ and $p$-Pb, at LHC energies resemble manifestations of collective behavior. This suggests that locally equilibrated matter may be produced in these small collision systems, similar to what is observed in Pb-Pb collisions. In this work, the same two-particle transverse momentum differential correlators are exploited in $pp$ and $p$-Pb collisions at $\sqrt{s}=7\text{TeV}$ and $\sqrt{s_{NN}}=5.02\text{TeV}$, respectively, to seek evidence for viscous effects. Specifically, the strength and shape of the correlators are studied as a function of the produced particle multiplicity to identify evidence for longitudinal broadening that might reveal the presence of viscous effects in these smaller systems. The measured correlators and their evolution from $pp$ and $p$-Pb to Pb-Pb collisions are additionally compared to predictions from Monte Carlo event generators, and the potential presence of viscous effects is discussed.

The expression for calculation of the heavy-ion fusion cross section is obtained in the case of approximation of the total heavy-ion potential around the barrier by the Morse potential. The approximation of the total heavy-ion potential around the barrier by the Morse potential is more realistic than the parabolic one. The asymptotic expressions of the fusion cross section at sub-barrier energies obtained for the Morse and parabolic approximations of the total heavy-ion potential have different dependencies on collision energy. The fusion cross sections calculated for the Morse and parabolic approximations of the total heavy-ion potential are discussed for the reactions ${}^{12}\mathrm{C}+{}^{24}\mathrm{Mg}$ and ${}^{12}\mathrm{C}+{}^{30}\mathrm{Si}$ in detail.

Background: Enhanced prescission neutron multiplicity (${\nu }_{\mathrm{pre}}$) over statistical model calculations assuming Bohr-Wheeler fission width is explained using Kramers' fission width incorporating dissipative effects. The dissipation strength obtained from such studies reported significant effect of the neutron shell closure of $N=126$ of the fissioning system as well as nuclear temperature. The dependence of dissipation strength on shell effect and temperature is also attributed to the choice of input parameters in the statistical model calculations.

Purpose: We investigate the role of $N/Z$, shell effect, collective enhancement of level density (CELD), and excitation energy on ${\nu }_{\mathrm{pre}}$ in reactions forming isotopes of the Ra nucleus.

Methods: The neutron multiplicity excitation function is measured for the ${}^{30}\mathrm{Si}+{}^{182,184,186}\mathrm{W}$ reactions populating ${}^{212,214,216}\mathrm{Ra}$ nuclei using the National Array of Neutron Detectors (NAND) at the Inter-University Accelerator Centre, New Delhi. Among these compound nuclei, ${}^{214}\mathrm{Ra}$ has a major neutron shell closure of $N=126$. Measured ${\nu }_{\mathrm{pre}}$ are analyzed within the framework of a statistical model incorporating dynamical hindrance in nuclear fission due to dissipation, shell corrections in the fission barrier and level density, and CELD.

Results: Experimental ${\nu }_{\mathrm{pre}}$ show a marginal isotopic dependence at all excitation energies. ${\nu }_{\mathrm{pre}}$ values do not show any noticeable effect of neutron magic number $N=126$. Dissipation strength of $\beta =8{\mathrm{zs}}^{-1}$ ($5.27\mathrm{MeV}/\hslash$) reasonably reproduces the experimental ${\nu }_{\mathrm{pre}}$ excitation functions for all three nuclei in the measured energy range. Appreciable variations in presaddle neutron emissions are observed when shell effect or CELD is excluded in the calculations. Even though both the shell and CELD are found to impact primarily in the presaddle sector, they alter the excitation energy and multiplicity in the saddle-to-scission sector as well in a complementary manner.

Conclusions: A temperature independent dissipation coefficient is observed to reproduce the experimental results in this study throughout the excitation energy range measured. Shell corrections in fission barrier and level density parameters and CELD in fission and particle evaporation widths also influence the neutron multiplicities. The observed effect of CELD in the presaddle phase is attributed to the large enhancement of level density at the saddle due to its large deformation and consequent enhancement of fission width.

We investigate the impact of nonvanishing net charge in collision systems on measurements of balance functions and their integrals. We show that the nominal balance function definition yields integrals that deviate from unity because of the nonvanishing net charge. However, the integral of unified balance functions is shown to appropriately converge to unity when measured in a sufficiently wide experimental acceptance. We furthermore explore the rate of convergence of unified balance functions integrals and study distortions imparted on the shape of balance functions when measurements are carried out in limited transverse momentum ($p_{\mathrm{T}}$) and rapidity ($y$) acceptances, such as those featured by experiments at the Large Hadron Collider or the Relativistic Heavy Ion Collider. We show that the shape and integral of unified balance functions may be strongly biased by reductions in the rapidity and transverse momentum acceptances of existing experiments.

Flow fluctuations in ultrarelativistic heavy-ion collisions can be probed by studying the momentum dependent correlations or the factorization-breaking coefficients between flow harmonics in separate kinematic bins (transverse momentum $p$ or pseudorapidity $\eta$). We study such factorization-breaking coefficients for collisions of deformed ${}^{238}\mathrm{U}+{}^{238}\mathrm{U}$ nuclei to see the effect of the nuclear deformation on momentum dependent coefficients. We also study momentum dependent mixed-flow correlations for the isobar collision system: ${}^{96}\mathrm{Ru}+{}^{96}\mathrm{Ru}$ and ${}^{96}\mathrm{Zr}+{}^{96}\mathrm{Zr}$, which have the same mass number but different nuclear structure, thus providing the ideal scenario to study nuclear deformation effect on such observables. We use the TRENTO $+$ MUSIC model for simulations and event-by-event analysis of those observables. We find that these momentum dependent correlation coefficients are not only excellent candidates to probe the fluctuation in heavy-ion collision, but also show significant sensitivity to the nuclear deformation.

We study the momentum and centrality dependence of the nonprompt $J/\psi$ nuclear modification factors ($R_{AA}$), which come from the $B$ hadron decay, in Pb-Pb collisions at the Large Hadron Collider. Bottom quarks are produced in the parton hard scatterings and suffer energy loss in the quark-gluon plasma and the hadronic gas, where the spatial and time evolution of the medium is described with the hydrodynamic equations. Medium-induced elastic scatterings and the radiation in bottom quarks are included in the energy loss of bottom quarks. The hadronization process of bottom quarks is described with the instantaneous coalescence model. After considering both cold and hot nuclear matter effects in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV, we calculated the $R_{AA}$ and also the elliptic flows of nonprompt $J/\psi$ from the decay of $B$ mesons at different centralities and transverse momentum bins. The $R_{AA}$ and $v_2$ of nonprompt $J/\psi$ sensitive to the hot medium reflect and centrality supply an opportunity to study the bottom quarks energy loss in the hot medium.

In the present work, we constrain the equation of state of dense matter in the context of heaviest observed neutron-star mass $M_{\max }=(2.35\pm 0.17)M_{\odot }$ for the black widow pulsar PSR J0952-0607. We propose three interactions HPU1, HPU2 and HPU3 (named after Himachal Pradesh University) for the relativistic mean-field model, which include different combinations of nonlinear, self-couplings, and cross couplings among isoscalar-scalar $\sigma$, and isoscalar-vector $\omega$ and isovector-vector $\rho$ meson fields up to the quartic order. These interactions are in harmony with the finite nuclei and bulk nuclear matter properties. The equations of state computed by using newly generated interactions for the $\beta$-equilibrated nucleonic matter satisfy the heaviest observed neutron-star mass $M_{\max }=(2.35\pm 0.17)M_{\odot }$ for the black widow pulsar PSR J0952-0607. The results for the radius $R_{1.4}$ and dimensionless tidal deformability ${\mathrm{\Lambda }}_{1.4}$ corresponding to the canonical mass are also presented and agree well with the GW170817 event and astrophysical observations. The radius of $2.08M_{\odot }$ neutron-star mass is predicted to be in the range $R_{2.08}=12.98$–13.09 km which also satisfy the NICER observations by Miller et al. [Astrophys. J. Lett. 918, L28 (2021)] and Riley et al. [Astrophys. J. Lett. 918, L27 (2021)]. A covariance analysis is also performed to assess the theoretical uncertainties of model parameters and to determine their correlations with nuclear matter observables.