Tue·Dec 10, 2024Tuesday·December 10, 2024

1. 01*

   In-beam $\gamma$-ray spectroscopy towards the proton dripline: The curious case of ${}^{32}$Ar

   T. Beck · A. Gade🇺🇸 · B. A. Brown🇺🇸 · Y. Utsuno🇯🇵 · D. Weisshaar🇺🇸 · D. Bazin🇺🇸 · K. W. Brown🇺🇸 · R. J. Charity🇺🇸 · P. J. Farris · S. A. Gillespie🇨🇦 · A. M. Hill · J. Li🇨🇳 and 3 other authors

   High-resolution in-beam $\gamma$-ray spectroscopy was used to study excited states of the neutron-deficient nucleus ${}^{32}$Ar populated in fast-beam induced four- and six-nucleon removal reactions from ${}^{36,38}$Ca. One new $\gamma$-ray transition and indications for an additional two were found, allowing for a glimpse at the level scheme beyond the known $2_1^{+}$ state. The nature of the new $1900(4)$-keV transition is discussed in the context of the known energy spectrum of the mirror nucleus ${}^{32}$Si and shell-model calculations using the FSU and SDPF-M cross-shell effective interactions. Its resulting parent state at $3767(5)$ keV, more than $1.3$ MeV above the proton separation energy, is tentatively assigned to have mixed sd-shell and $2p$-$2h$ character. It might either be the mirror of the $J^{\pi }=2_2^{+}$ state of ${}^{32}$Si at $4230.8(8)$ keV, but with a decay branch favoring a transition to the $2_1^{+}$ over the ground state, or the mirror of the $4983.9(11)$-keV state with quantum numbers $0^{+}$. The resulting mirror-energy differences of $-473(5)$ and $-1218(5)$ keV are both sizable when compared to systematics; in the latter case it would, in fact, be among the largest reported to date in the entire nuclear chart or suggest the potential existence of an additional, hitherto unidentified, low-lying $0^{+}$ state of ${}^{32}$Si.

   nucl-exPRC(2025)·1 citation
2. 02*

   On the quarkonium-in-jet collinear fragmentation at moderate-to-large transverse momentum

   Francesco Giovanni Celiberto🇪🇸

   We report progress on the Heavy-Flavor Non-Relativistic Evolution (HF-NRevo) setup, a novel methodology to address quarkonium formation within the fragmentation approximation. Our study sheds light on the moderate to large transverse-momentum sector, where the leading-twist collinear fragmentation of a single parton prevails over the higher-twist fragmentation from a constituent heavy-quark pair produced in the hard scattering. As for the initial energy-scale inputs, we rely on nonrelativistic next-to-leading calculations for all the parton-to-quarkonia fragmentation channels. Preliminary sets of variable-flavor number-scheme (VFNS) fragmentation functions, named NRFF1.0, are built via an evolution-threshold enhanced DGLAP scheme. Taking NRFF1.0 as a starting point, we use HF-NRevo to address the collinear fragmentation of quarkonia inside jets.

   ↳ hep-phhep-exnucl-exnucl-thActa Phys.Polon.Supp.(2025)·15 citations
3. 03*

   Large-scale shell-model study of 2$\nu$ECEC process in ${}^{78}$Kr

   Deepak Patel🇮🇳 · Praveen C. Srivastava🇮🇳

   In this work, we present the systematic study of $2\nu$ECEC process in the ${}^{78}$Kr using large-scale shell-model calculations with the GWBXG effective interaction. We first validate the efficiency of the utilized interaction by comparing the theoretical low-lying energy spectra, the kinematic moment of inertia, and reduced transition probabilities with the experimental data for both the parent and grand-daughter nuclei ${}^{78}$Kr and ${}^{78}$Se, respectively. Additionally, we examine the shell-model level densities of the $1^{+}$ states in the intermediate nucleus ${}^{78}$Br, comparing them with the predictions from the Back-shifted Fermi gas model. We analyze the variation of cumulative nuclear matrix elements (NMEs) for the $2\nu$ECEC process in ${}^{78}$Kr as a function of $1^{+}$ state energies in the intermediate nucleus ${}^{78}$Br up to the saturation level. Our estimated half-life for ${}^{78}$Kr, extracted from the shell-model predicted NMEs, shows good agreement with the experimental value. The Gamow-Teller transitions from the lowest $1^{+}$ state of ${}^{78}$Br via both the EC$+{\beta }^{+}$ and ${\beta }^{-}$-channels are also discussed.

   ↳ nucl-thnucl-exPhys.Scripta(2025)·2 citations
4. 04*

   Implications of latest NICER data for the neutron star equation of state

   Len Brandes🇩🇪 · Wolfram Weise🇩🇪

   As an update to our previously performed Bayesian inference analyses of the neutron star matter equation-of-state and related quantities, the additional impact of the recently published NICER data of PSR J0437-4751 is examined. Including the mass and radius distributions of this pulsar in our data base results in modest shifts from previously inferred median posterior values of radii $R$ and central densities $n_c$ for representative $1.4M_{\odot }$ and $2.1M_{\odot }$ neutron stars: radii are reduced by about $0.2-0.3$ km to values of $R_{1.4}=12.1\pm 0.5$ km and $R_{2.1}=11.9_{-0.6}^{+0.5}$ km (at the 68\% level), and central densities increase slightly to values of $n_c(1.4M_{\odot })/n_0=2.8\pm 0.3$ and $n_c(2.1M_{\odot })/n_0=3.8_{-0.7}^{+0.6}$ (in units of equilibrium nuclear matter density, $n_0=0.16$ fm${}^{-3}$), i.e., they still fall below five times nuclear saturation density at the 68\% level. As a further significant result, the evidence established by analyzing Bayes factors for a negative trace anomaly measure, $\Delta =1/3-P/\epsilon <0$, inside heavy neutron stars is raised to strong.

   ↳ nucl-thastro-ph.HEgr-qcnucl-exPRD(2025)·31 citations
5. 05*

   Testing for isospin symmetry breaking with extensive calculations of isotope shift factors in potassium

   Vaibhav Katyal🇮🇳 · A. Chakraborty🇮🇳 · B. K. Sahoo🇮🇳 · Ben Ohayon🇮🇱 · Chien-Yeah Seng🇺🇸 · Mikhail Gorchtein🇩🇪 · John Behr🇨🇦

   Precise evaluation of the isotope shift (IS) factors for seven low-lying potassium (K) states is achieved using relativistic coupled-cluster (RCC) theory. The energies of these states are assessed and compared with experimental data to confirm the accuracy of the wave functions calculated at varying RCC theory approximations and highlight the significance of many-body and relativistic effects in determining the energies and IS factors of K. Various methods are used to compute the IS factors, with the finite-field (FF) approach yielding results that align with observed and semi-empirical data. This consistency is attributed to orbital relaxation effects that are naturally present in the FF method but emerge only through complex interactions in other techniques. Using the IS factors derived from FF, we review the mean square radius difference between ${}^{38m}$K and ${}^{39}$K. From this difference and muonic atom x-ray spectroscopy, we deduce the absolute radius of ${}^{38m}$K using an updated calculation of the nuclear polarizability effect. Finally, we evaluate the isospin symmetry breaking (ISB) in this isotriplet by integrating the radius of ${}^{38m}$K with an updated radius of ${}^{38}$Ca, concluding that the ISB is compatible with zero. This finding offers a stringent benchmark for nuclear model calculations of ISB corrections in nuclear beta decay, which play a key role in determining the $V_{ud}$ matrix element.

   ↳ physics.atom-phhep-phnucl-exnucl-thPRA(2025)·13 citations
6. 06*

   Identifying weak critical fluctuations of intermittency in heavy-ion collisions with topological machine learning

   Rui Wang🇨🇳 · Chengrui Qiu🇨🇳 · Chuan-Shen Hu🇸🇬 · Zhiming Li🇨🇳 · Yuanfang Wu🇨🇳

   Large density fluctuations of conserved charges have been proposed as a promising signature for exploring the QCD critical point in heavy-ion collisions. These fluctuations are expected to exhibit a fractal or scale-invariant behavior, which can be probed by intermittency analysis. Recent high-energy experimental studies reveal that the signal of critical fluctuations related to intermittency is very weak and thus could be easily obscured by the overwhelming background particles in the data sample. Employing a point cloud neural network with topological machine learning, we can successfully classify weak signal events from background noise by the extracted distinct topological features, and accurately determine the intermittency index for weak signal event samples.

   ↳ nucl-thhep-phnucl-exPLB(2025)·6 citations
7. 07*

   Determining Absolute Neutrino Mass using Quantum Technologies

   A. A. S. Amad🇬🇧 · F. F. Deppisch🇬🇧 · M. Fleck🇬🇧 · J. Gallop🇬🇧 · T. Goffrey🇬🇧 · L. Hao🇬🇧 · N. Higginbotham🇬🇧 · S. D. Hogan🇬🇧 · S. B. Jones🇬🇧 · L. Li🇬🇧 · N. McConkey🇬🇧 · V. Monachello🇬🇧 and 10 other authors

   Next generation tritium decay experiments to determine the absolute neutrino mass require high-precision measurements of $\beta$-decay electron energies close to the kinematic end point. To achieve this, the development of high phase-space density sources of atomic tritium is required, along with the implementation of methods to control the motion of these atoms to allow extended observation times. A promising approach to efficiently and accurately measure the kinetic energies of individual $\beta$-decay electrons generated in these dilute atomic gases, is to determine the frequency of the cyclotron radiation they emit in a precisely characterised magnetic field. This cyclotron radiation emission spectroscopy technique can benefit from recent developments in quantum technologies. Absolute static-field magnetometry and electrometry, which is essential for the precise determination of the electron kinetic energies from the frequency of their emitted cyclotron radiation, can be performed using atoms in superpositions of circular Rydberg states. Quantum-limited microwave amplifiers will allow precise cyclotron frequency measurements to be made with maximal signal-to-noise ratios and minimal observation times. Exploiting the opportunities offered by quantum technologies in these key areas, represents the core activity of the Quantum Technologies for Neutrino Mass project. Its goal is to develop a new experimental apparatus that can enable a determination of the absolute neutrino mass with a sensitivity on the order of 10~meV/$c^2$.

   ↳ hep-exnucl-exphysics.atom-phquant-phNew J.Phys.(2025)·14 citations
8. 08*

   Jet momentum reconstruction in the QGP background with machine learning

   Ran Li🇨🇳 · Yi-Lun Du🇨🇳 · Shanshan Cao🇨🇳

   We apply a Dense Neural Network (DNN) approach to reconstruct jet momentum within a quark-gluon plasma (QGP) background, using simulated data from PYTHIA and Linear Boltzmann Transport (LBT) Models for comparative analysis. We find that medium response particles from the LBT simulation, scattered out of the QGP background but belonging to medium-modified jets, lead to oversubtraction of the background if the DNN model is trained on vacuum jets from PYTHIA simulation. By training the DNN model on quenched jets generated using LBT or the combination of jet samples from PYTHIA and LBT, we significantly reduce this prediction bias and achieve more accurate background subtraction compared to conventional Area-based and Constituent Subtraction methods widely adopted in experimental measurements. We further study the performance of these machine learning models on evaluating the nuclear modification factor of jets, and find that while the unfolding procedure is necessary for correcting residuals in reconstructed jet momenta, models trained on samples incorporating quenched jets still achieve superior accuracy than those trained on vacuum jets even after unfolding.

   ↳ hep-phnucl-exnucl-thPLB(2025)·3 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.