Tue·Oct 8, 2024Tuesday·October 8, 2024

1. 01*

   Final Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of ${}^{76}$Ge to Excited States of ${}^{76}$Se

   I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · E. Blalock🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · Y.-D. Chan🇺🇸 · J.R. Chapman🇺🇸 · C.D. Christofferson🇺🇸 · P.-H. Chu🇺🇸 · C. Cuesta🇪🇸 · J.A. Detwiler🇺🇸 and 36 other authors

   ${}^{76}$Ge can $\beta \beta$ decay into three possible excited states of ${}^{76}$Se, with the emission of two or, if the neutrino is Majorana, zero neutrinos. None of these six transitions have yet been observed. The MAJORANA DEMONSTRATOR was designed to study $\beta \beta$ decay of ${}^{76}$Ge using a low background array of high purity germanium detectors. With 98.2 kg-y of isotopic exposure, the DEMONSTRATOR sets the strongest half-life limits to date for all six transition modes. For $2\nu \beta \beta$ to the $0_1^{+}$ state of ${}^{76}$Se, this search has begun to probe for the first time half-life values predicted using modern many-body nuclear theory techniques, setting a limit of $T_{1/2}>1.5\times 10^{24}$ y (90% CL).

   nucl-exPRL(2025)·6 citations
2. 02*

   Azimuthal Anisotropy Scaling for Identified Mesons and Baryons: Insights into Medium Transport Properties, Equation of State and Hadronic Re-scattering

   Roy A. Lacey (Department of Chemistry, Stony Brook University, Stony Brook, NY, USA)🇺🇸

   Scaling functions for the centrality and transverse momentum dependence of \(v_2(p_T,\text{cent})\) and \(v_3(p_T,\text{cent})\) are constructed for identified mesons and baryons in Pb+Pb (\(\sqrt{s_{NN}}=2.76,\ 5.02\)~TeV), Xe+Xe (5.44~TeV), and Au+Au (0.2~TeV) collisions. These species-resolved functions capture the interplay of initial geometry, viscous attenuation, radial flow, partonic energy loss, and hadronic re-scattering across both flow- and quenching-dominated regimes. The systematic growth of the radial-flow parameter \(\zeta_{\rm rf}\) with multiplicity and beam energy provides direct empirical constraints on the equation of state (EOS) of hot QCD matter. The extracted parameters also yield differential constraints on the specific shear viscosity \(\eta/s\), the jet-quenching parameter \(\hat{q}\), and late-stage hadronic dynamics. LHC systems exhibit low \(\eta/s\), strong radial flow, and negligible re-scattering at high energy density, whereas Au+Au at RHIC energy shows even lower \(\eta/s\), weaker radial flow, finite re-scattering, and reduced energy density. The coexistence of strong radial flow at low \(p_T\) and significant jet suppression at high \(p_T\) emerges as a defining hallmark of QGP formation, establishing the framework as a quantitative probe of QGP transport properties and EOS stiffness.

   nucl-exhep-exhep-phnucl-th2 citations
3. 03*

   Correlations between azimuthal anisotropy and mean transverse momentum in pp, pPb, and peripheral PbPb collisions

   CMS Collaboration

   Correlations between azimuthal anisotropy and mean transverse momentum of charged particles in proton-proton (pp), proton-lead (pPb), and peripheral lead-lead (PbPb) collisions are presented as a function of charged particle multiplicity. The pp, pPb and PbPb collision data were collected using the CMS detector at the LHC with a center-of-mass energy per nucleon pair of 13, 8.16 and 5.02 TeV, respectively. The two- and four-particle cumulants for the second- and third-order Fourier anisotropy harmonics are correlated with the mean transverse momentum of charged particles on an event-by-event basis. In pp and pPb systems, the observed correlation coefficients based on two-particle cumulants are found to change from negative to positive values as the charged particle multiplicity decreases. The sign changes disappear when the correlated particles are required to be further apart in pseudorapidity. Additionally, no sign changes in correlation coefficients are observed when employing four-particle cumulants. Models incorporating initial-state gluon saturation and final-state hydrodynamic evolutions are compared to pPb data and the predicted sign changes are not observed.

   nucl-exhep-ex7 citations
4. 04*

   High-precision mass measurement of ${}^{103}$Sn restores smoothness of the mass surface

   C. M. Ireland🇺🇸 · F. M. Maier🇺🇸 · G. Bollen🇺🇸 · S. E. Campbell🇺🇸 · X. Chen🇨🇳 · H. Erington🇺🇸 · N. D. Gamage🇺🇸 · M. J. Gutiérrez🇩🇪 · C. Izzo🇨🇦 · E. Leistenschneider🇺🇸 · E. M. Lykiardopoulou🇨🇦 · R. Orford🇺🇸 and 11 other authors

   As a step towards the ultimate goal of a high-precision mass measurement of doubly-magic ${}^{100}$Sn, the mass of ${}^{103}$Sn was measured at the Low Energy Beam and Ion Trap (LEBIT) located at the Facility for Rare Isotope Beams (FRIB). Utilizing the time-of-flight ion cyclotron resonance (ToF-ICR) technique, a mass uncertainty of 3.7~keV was achieved, an improvement by more than an order of magnitude compared to a recent measurement performed in 2023 at the Cooler Storage Ring (CSRe) in Lanzhou. Although the LEBIT and CSRe mass measurements of ${}^{103}$Sn are in agreement, they diverge from the experimental mass value reported in the 2016 version of the Atomic Mass Evaluation (AME2016), which was derived from the measured $Q_{{\beta }^{+}}$ value and the mass of ${}^{103}$In. In AME2020, this indirectly measured ${}^{103}$Sn mass was classified as a `seriously irregular mass' and replaced with an extrapolated value, which aligns with the most recent measured values from CSRe and LEBIT. As such, the smoothness of the mass surface is confidently reestablished for ${}^{103}$Sn. Furthermore, LEBIT's mass measurement of ${}^{103}$Sn enabled a significant reduction in the mass uncertainties of five parent isotopes which are now dominated by uncertainties in their respective $Q$-values.

   nucl-exPRC(2025)·12 citations
5. 05*

   RESuM: Rare Event Surrogate Model for Physics Detector Design

   Ann-Kathrin Schuetz🇺🇸 · Alan W. P. Poon🇺🇸 · Aobo Li🇺🇸

   The experimental discovery of neutrinoless double-beta decay (NLDBD) would answer one of the most important questions in physics: Why is there more matter than antimatter in our universe? To maximize the chances of detection, NLDBD experiments must optimize their detector designs to minimize the probability of background events contaminating the detector. Given that this probability is inherently low, design optimization either requires extremely costly simulations to generate sufficient background counts or contending with significant variance. In this work, we formalize this dilemma as a Rare Event Design (RED) problem: identifying optimal design parameters when the design metric to be minimized is inherently small. We then designed the Rare Event Surrogate Model (RESuM) for physics detector design optimization under RED conditions. RESuM uses a pretrained Conditional Neural Process (CNP) model to incorporate additional prior knowledges into a Multi-Fidelity Gaussian Process model. We applied RESuM to optimize neutron moderator designs for the LEGEND NLDBD experiment, identifying an optimal design that reduces neutron background by ($66.5\pm 3.5$)% while using only 3.3% of the computational resources compared to traditional methods. Given the prevalence of RED problems in other fields of physical sciences, the RESuM algorithm has broad potential for simulation-intensive applications.

   ↳ physics.ins-dethep-exnucl-ex0 citations
6. 06*

   Impressions of Parton Distribution Functions

   Yang Yu🇨🇳 · Craig D. Roberts🇨🇳

   Parton distribution functions (DFs) have long been recognised as key measures of hadron structure. Today, theoretical prediction of such DFs is becoming possible using diverse methods for continuum and lattice analyses of strong interaction (QCD) matrix elements. Recent developments include a demonstration that continuum and lattice analyses yield mutually consistent results for all pion DFs, with behaviour on the far valence domain of light-front momentum fraction that matches QCD expectations. Theory is also delivering an understanding of the distributions of proton mass and spin amongst its constituents, which varies, of course, with the resolving scale of the measuring probe. Aspects of the pion DF and proton spin developments are sketched herein, along with some novel perspectives on gluon and quark orbital angular momentum.

   ↳ hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2024)·21 citations
7. 07*

   Machine learning-powered data cleaning for LEGEND: a semi-supervised approach using affinity propagation and support vector machines

   E. León🇺🇸 · A. Li🇺🇸 · M. A. Bahena Schott🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · J. R. Chapman🇺🇸 · G. L. Duran🇺🇸 · J. Gruszko🇺🇸 · R. Henning🇺🇸 · E. L. Martin🇺🇸 · J. F. Wilkerson🇺🇸

   Neutrinoless double-beta decay ($0\nu \beta \beta$) is a rare nuclear process that, if observed, will provide insight into the nature of neutrinos and help explain the matter-antimatter asymmetry in the universe. The Large Enriched Germanium Experiment for Neutrinoless Double-Beta Decay (LEGEND) will operate in two phases to search for $0\nu \beta \beta$. The first (second) stage will employ 200 (1000) kg of High-Purity Germanium (HPGe) enriched in ${}^{76}$Ge to achieve a half-life sensitivity of 10${}^{27}$ (10${}^{28}$) years. In this study, we present a semi-supervised data-driven approach to remove non-physical events captured by HPGe detectors powered by a novel artificial intelligence model. We utilize Affinity Propagation to cluster waveform signals based on their shape and a Support Vector Machine to classify them into different categories. We train, optimize, test our model on data taken from a natural abundance HPGe detector installed in the Full Chain Test experimental stand at the University of North Carolina at Chapel Hill. We demonstrate that our model yields a maximum sacrifice of physics events of $0.024_{-0.003}^{+0.004}\%$. Our model is being used to accelerate data cleaning development for LEGEND-200 and will serve to improve data cleaning procedures for LEGEND-1000.

   ↳ physics.data-annucl-exphysics.ins-detMach.Learn.Sci.Tech.(2025)·0 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.