Wed·Jun 4, 2025Wednesday·June 4, 2025

1. 01*

   Measurement of the longitudinal flow-plane decorrelation using multi-plane cumulants in $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 200 GeV Au+Au, Ru+Ru, and Zr+Zr collisions

   STAR Collaboration

   Measurements of the variation of anisotropic flow-plane angles (${\Psi }_n$) with rapidity, commonly known as the flow-plane decorrelation, provide important insights into the initial conditions of the matter produced in heavy-ion collisions. In this paper, using data collected by the STAR experiment, we report the first measurement of the four-plane correlator observable $T_n\{ba;dc\}=⟨⟨\sin [n({\Psi }_n^b-{\Psi }_n^a)]\sin [n({\Psi }_n^d-{\Psi }_n^c)]⟩⟩$, where superscripts $a$, $b$, $c$, and $d$ denote sequential pseudorapidity ($\eta$) regions with $a$ corresponding to the most backward region, $b$ and $c$ close to mid-rapidity with ${\eta }_b<0$ and ${\eta }_c>0$, and $d$ being the most forward. The measurement is performed for the elliptic and triangular flow (i.e. $n=2$ and $3$) in Au+Au and isobar (Ru+Ru, Zr+Zr) collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 200 GeV. The goal of calculating the correlation of the flow-plane angle variations from backward to mid-central, and from mid-central to forward regions, is to probe the systematic variation of flow angle over a wide $\eta$ range. In mid-central collisions ($10-30\%$ centrality), we find $T_2\{ba;dc\}=-0.004\pm 0.001(\mathrm{stat})\pm 0.002(\mathrm{syst})$ independent of the collision system. Such a small value of $T_2$ favors a ''random-walk'' variation of the flow-plane angles, where the rapidity correlation length is smaller than the entire region under study. These measurements provide new information on the decorrelation patterns in the system and offer a quantitative estimate of possible systematic variations in anisotropic flow angles such as ''twist'' between forward and backward regions. This opens new opportunities for understanding the three-dimensional structure and the time evolution of the quark-gluon plasma created in heavy-ion collisions.

   nucl-exhep-exPRC(2026)·4 citations
2. 02*

   Extremely large oblate deformation of the first excited state in ${}^{12}$C: a new challenge to modern nuclear theory

   C. Ngwetsheni🇿🇦 · J. N. Orce🇿🇦 · P. Navrátil🇨🇦 · P. E. Garrett🇨🇦 · T. Faestermann🇩🇪 · A. Bergmaier🇩🇪 · M. Frosini🇫🇷 · V. Bildstein🇨🇦 · B. A. Brown🇺🇸 · C. Burbadge🇨🇦 · T. Duguet🇫🇷 · K. Hadyńska-Klȩk and 5 other authors

   A Coulomb-excitation study of the high-lying first excited state at 4.439 MeV in the nucleus ${}^{12}$C has been carried out using the ${}^{208}$Pb(${}^{12}$C,${}^{12}$C${}^{\ast }$)${}^{208}$Pb${}^{\ast }$ reaction at 56 MeV and the {\sc Q3D} magnetic spectrograph at the Maier-Leibnitz Laboratorium in Munich. High-statistics achieved with an average beam intensity of approximately 10${}^{11}$ ions/s together with state-of-the-art {\it ab initio} calculations of the nuclear dipole polarizability permitted the accurate determination of the spectroscopic quadrupole moment, $Q_{{}_S}(2_{{}_1}^{+})=+0.076(30)$~eb, in agreement with previous measurements. Combined with previous work, a weighted average of $Q_{{}_S}(2_{{}_1}^{+})=+0.090(14)$ eb is determined, which includes the re-analysis of a similar experiment by Vermeer and collaborators, $Q_{{}_S}(2_{{}_1}^{+})=+0.103(20)$~eb. Such a large oblate deformation challenges modern nuclear theory and emphasizes the need of $\alpha$ clustering and associated triaxiality effects for full convergence of $E2$ collective properties.

   nucl-exnucl-thphysics.data-an1 citation
3. 03*

   Investigating the inclusive $D^0$ photoproduction in ultraperipheral $PbPb$ collisions at the Large Hadron Collider

   Victor P. Goncalves🇧🇷 · Luana Santana🇧🇷 · Wolfgang Schäfer🇵🇱

   The inclusive $D^0$ photoproduction in $PbPb$ collisions at the center - of - mass energies of the Large Hadron Collider (LHC) is investigated considering the color dipole $S$ - matrix approach. The analytical expressions for the differential distributions are derived in the impact parameter and transverse momentum spaces and predictions for the rapidity and transverse momentum distributions are presented considering three distinct models for the unintegrated gluon distribution of the nuclear target. In particular, we compare the predictions derived assuming a linear dynamics, with and without the inclusion of nuclear effects, with those obtained by solving the running coupling Balitsky - Kovchegov equation. A comparison of these predictions with the recent (preliminary) CMS data is also performed. Our results indicate that a detailed analysis of this observable will be very useful to improve our understanding of the strong interaction theory at high energies and in a nuclear medium.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2025)·6 citations
4. 04*

   Classification of Hoyle State Decay Branches in Active Target Time Projection Chamber using Neural Network

   Pralay Kumar Das🇮🇳 · Nayana Majumdar · Supratik Mukhopadhyay

   A multi-class convolutional neural network (CNN) model has been developed using Keras deep learning library in Python for image-based classification of ${}^{12}$C Hoyle state decay branches from tracking information, recorded by Saha Active Target Time Projection Chamber, SAT-TPC (currently under development). The nuclear events, produced by the 30 MeV $\alpha$-particle beam in the SAT-TPC, filled with Ar + CO${}_2$ (90:10) gas mixture at atmospheric pressure, have been considered for training and validation of the models. The elastic scattering and Hoyle state sequential and direct decay events in the interaction of $\alpha$-particle with ${}^{40}$Ar, ${}^{12}$C, ${}^{16}$O nuclei have been generated through Monte-Carlo simulation. The three-dimensional tracks, produced by the scattering and decay products through primary ionization of gaseous medium, have been simulated with Geant4. The primary tracks, distributed on the beam-plane, have been convoluted with electron diffusion, obtained with Magboltz, to produce the final tracking information. The classification performance of the proposed model for different readout segmentation schemes of the SAT-TPC has been discussed.

   ↳ physics.ins-detnucl-exphysics.data-anJINST(2025)·1 citation
5. 05*

   Ab initio study of the radii of oxygen isotopes

   Zhengxue Ren🇩🇪 · Serdar Elhatisari🇹🇷 · Ulf-G. Meißner🇩🇪

   We present an {\em ab initio} study of the charge and matter radii of oxygen isotopes from ${}^{16}$O to ${}^{20}$O using nuclear lattice effective field theory (NLEFT) with high-fidelity N${}^3$LO chiral interactions. To efficiently address the Monte Carlo sign problem encountered in nuclear radius calculations, we introduce the {\em partial pinhole algorithm}, significantly reducing statistical uncertainties and extending the reach to more neutron-rich and proton-rich isotopes. Our computed charge radii for ${}^{16}$O, ${}^{17}$O, and ${}^{18}$O closely match experimental data, and we predict a charge radius of $2.810(32)$ fm for ${}^{20}$O. The calculated matter radii show excellent agreement with values extracted from low-energy proton and electron elastic scattering data, but are inconsistent with those derived from interaction cross sections and charge-changing cross section measurements. These discrepancies highlight model-dependent ambiguities in the experimental extraction methods of matter radii and underscore the value of precise theoretical benchmarks from NLEFT calculations.

   ↳ nucl-thhep-latnucl-exPRL(2025)·15 citations
6. 06*

   High-order anisotropic flow and nonlinear hydrodynamic responses

   Owen Horecny🇺🇸 · Chun Shen🇺🇸

   In this work, we study the charged hadron anisotropic flow coefficients $v_n$ (up to $n=12$) using high-statistics event-by-event simulations of Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ and $5.36$~TeV, employing the IP-Glasma + MUSIC + UrQMD hybrid approach. The power spectra of anisotropic flow coefficients ($v_n\{2\}$ vs. $n$) are compared with the ALICE measurements from central to 50% centrality. To understand the various sources contributing to the high-order $v_n$ coefficients, we analyze the nonlinear mode coefficients for high-order anisotropic flow coefficients using different approximations and make comparisons with available measurements.

   ↳ nucl-thhep-phnucl-exPRC(2025)·1 citation
7. 07*

   ${}^{229}$Th Nuclear Spectroscopy in an Opaque Material: Laser-Based Conversion Electron Mössbauer Spectroscopy of ${}^{229}$ThO${}_2$

   Ricky Elwell🇺🇸 · James E. S. Terhune🇺🇸 · Christian Schneider🇦🇹 · Harry W. T. Morgan🇺🇸 · Hoang Bao Tran Tan🇺🇸 · Udeshika C. Perera🇺🇸 · Daniel A. Rehn · Marisa C. Alfonso · Lars von der Wense · Benedict Seiferle · Kevin Scharl🇩🇪 · Peter G. Thirolf🇩🇪 · Andrei Derevianko🇺🇸 · Eric R. Hudson🇺🇸

   Here, we report the first demonstration of laser-induced conversion electron Mössbauer spectroscopy of the ${}^{229}$Th nuclear isomeric state, which provides the ability to probe the nuclear transition in a material that is opaque to light resonant with the nuclear transition. Specifically, we excite the nuclear transition in a thin ThO${}_2$ sample whose band gap ($\sim$ 6 eV) is considerably smaller than the nuclear isomeric state energy (8.4 eV). As a result, the excited nucleus can quickly decay by internal conversion, resulting in the ejection of electrons from the surface. By collecting these conversion electrons, nuclear spectroscopy can be recorded. Unlike fluorescence spectroscopy, this technique is compatible with materials whose work function is less than the nuclear transition energy, opening a wider class of systems to study. Further, because ThO${}_2$ can be made from spinless isotopes and the internal conversion decay process reduces the isomeric state lifetime to only $\sim$10 $\mu$s, allowing $\sim$10${}^8$ relative reduction in clock interrogation time, a conversion-electron-based nuclear clock could lead to a $\sim$10${}^4$ reduction in clock instability.

   ↳ physics.atom-phnucl-exphysics.opticsquant-ph8 citations
8. 08*

   Measurement of the Positive Muon Anomalous Magnetic Moment to 127 ppb

   The Muon $g-2$ Collaboration: D. P. Aguillard (33) · T. Albahri (30) · D. Allspach (7) · J. Annala (7) · K. Badgley (7) · S. Baeßler (35) · I. Bailey (16) · L. Bailey (27) · E. Barlas-Yucel (28) · T. Barrett (6) · E. Barzi (7) · F. Bedeschi (10) and 182 other authors

   A new measurement of the magnetic anomaly $a_{\mu }$ of the positive muon is presented based on data taken from 2020 to 2023 by the Muon $g-2$ Experiment at Fermi National Accelerator Laboratory (FNAL). This dataset contains over 2.5 times the total statistics of our previous results. From the ratio of the precession frequencies for muons and protons in our storage ring magnetic field, together with precisely known ratios of fundamental constants, we determine $a_{\mu }=1165920710(162)\times 10^{-12}$ (139 ppb) for the new datasets, and $a_{\mu }=1165920705(148)\times 10^{-12}$ (127 ppb) when combined with our previous results. The new experimental world average, dominated by the measurements at FNAL, is $a_{\mu }(\text{exp})=1165920715(145)\times 10^{-12}$ (124 ppb). The measurements at FNAL have improved the precision on the world average by over a factor of four.

   ↳ hep-exnucl-exPRL(2025)·250 citations
9. 09*

   Reducing Hadronic Uncertainty in Low-Energy Neutral-Current Processes

   Oleksandr Tomalak🇨🇳

   We analyze the hadronic uncertainty from light-quark loops coupled to (anti)neutrino in low-energy neutral-current (anti)neutrino scattering, estimated at the $3$-$4$ permille level. This uncertainty arises from limited knowledge of the charge-isospin correlation function of quark currents. We study the charge-charge and charge-isospin correlators within $\mathrm{SU}(2)$ and $\mathrm{SU}(3)$ chiral perturbation theory (ChPT). In $\mathrm{SU}(2)$ ChPT, the two correlators are identical to all orders in the chiral and electromagnetic expansions. We further perform a leading-order $\mathrm{SU}(3)$ ChPT calculation and discuss the relevant counterterms. Our findings reduce the hadronic uncertainty in neutral-current processes such as (anti)neutrino-electron and coherent elastic (anti)neutrino-nucleus scattering by a factor $\sim 35$.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2026)·3 citations
10. 10*

    Modelling Coincident Particle Production in Ultraperipheral Heavy Ion Collisions

    L. A. Harland-Lang🇬🇧

    In this paper, we present an analysis of coincident particle production in ultraperipheral heavy ion collisions. In particular, we present the first detailed and differential predictions for coincident ${\rho }^0$ meson production in association with muon pair production, motivated by the recent ATLAS measurement of this process. These are found to describe the data very well, including the dependence of the coincidence fraction on the ZDC selection and/or other kinematic constraints on the muons. Differential predictions at the level of various kinematic variables are presented, and the calculation is made publicly available in the SuperChic MC generator. We also present general results for coincident two-photon initiated production focussing on muon and electron pair production; while the former is rather suppressed, the latter will be ubiquitous at threshold. The impact of coincident production on exclusivity vetos in ultraperipheral measurements is in addition discussed.

    ↳ hep-phhep-exnucl-exnucl-thPRD(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.