PaperPanorama

Nuclear Experiment·nucl-ex

Tue·Jul 21, 2026

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    Study of production in pPb collisions at = 8.16 TeV

    CMS Collaboration

    Production of prompt P-wave charmonium states (1P) and (1P) is studied in proton-lead (pPb) collisions at a center-of-mass energy per nucleon pair of = 8.16 TeV. The analysis is based on data corresponding to an integrated luminosity of 175 nb collected by the CMS experiment at the CERN LHC. The states are measured via their decay J. The J meson is reconstructed via its decay to a muon pair, while the photon is reconstructed through its conversion to an electron-positron pair. The ratio of production cross sections times branching fractions for the two charmonium states, [ J)] / [ J], is reported in the rapidity range J 2.4 for the transverse momentum range 6.5 (J) 30 GeV. The -to- ratio is found to be independent of event charged-particle multiplicity, as well as of the rapidity and of the J. The consistency of this ratio with proton-proton measurements at = 7 TeV indicates an absence of strong relative modification for states in pPb collisions, in contrast to the behavior observed in the (2S)-to-J ratio.

    nucl-exhep-ex1 citation
  2. 02

    First measurement of production in collisions at = 5.02 TeV

    ALICE Collaboration

    The ALICE Collaboration reports the first measurement of the production of prompt baryons in nucleusnucleus collisions by analyzing data from collisions at . The production and transverse-momentum () differential spectra of are particularly sensitive to the hadronization process and to strangeness production in the quark--gluon plasma formed in high-energy heavy-ion collisions. The baryons are reconstructed at midrapidity () in the transverse-momentum intervals and in the 010\% and 3050\% centrality intervals, respectively. The nuclear modification factor () reaches values up to 3 in the interval , which is the largest value measured so far for charm hadrons. Model predictions are compatible with the measured , while, in the measured intervals, they underestimate the production yield as well as the measured , , and yield ratios.

    nucl-exhep-ex0 citations
  3. 03

    Transverse Charge Distribution as a Probe of Nucleon Transversity

    Wanchen Li🇨🇳 · Xiaohui Liu🇨🇳 · Ding Yu Shao🇨🇳

    We introduce the transverse charge distribution as a spin-sensitive charge-flow probe for fragmentation and nucleon tomography. By measuring the angular distribution of net electric charge around a fragmenting quark, this observable relies entirely on the tracking of charged-particle directions and charge signs, strictly bypassing the need for calorimetric energy measurements. At leading twist, the distribution decomposes into an unpolarized charge monopole and a chiral-odd transverse charge dipole. We derive the operator product expansion of these distributions onto charge-weighted collinear moments: a charge monopole and a charge dipole governed by the Collins effect and couples directly to transversity. Applying this formalism to transversely polarized collisions at RHIC, we show that charge weighting suppresses the unpolarized monopole background and causes the spin-dependent dipoles from oppositely charged hadrons to add coherently. This coherence strongly enhances the resulting azimuthal asymmetries, establishing a theoretically clean and experimentally precise track-only avenue for extracting transversity.

    ↳ hep-phhep-exnucl-exnucl-th1 citation
  4. 04

    Long-Lived Dark Hadrons at the Electron-Ion Collider

    Hooman Davoudiasl🇺🇸 · Hongkai Liu🇺🇸 · Ethan T. Neil🇺🇸

    We study a dark non-Abelian gauge sector with GeV-scale confinement. The dark sector is assumed to couple only feebly to the Standard Model, while its low-energy spectrum may contain long-lived flavor-diagonal dark pions. Signals of these states are particularly well suited to the Electron-Ion Collider (EIC), where the absence of a hard trigger requirement and the capability to record soft final-state particles offer a complementary probe of dark hadronization dynamics. We present a benchmark portal construction, discuss the mixing between an axion-like mediator and dark pions, and identify the resulting displaced-decay signature.

    ↳ hep-phhep-exnucl-ex0 citations
  5. 05

    Wounded parton scaling of multiplicities in ultra-relativistic light- and heavy-ion collisions

    Rupam Samanta🇵🇱 · Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱

    Multiplicities of charged particles produced in O+O, Ne+Ne, Xe+Xe, and Pb+Pb collisions at ~TeV are studied in a uniform way within a wounded parton Glauber framework with overlaid negative binomial fluctuations. In this model, the nucleon's inelastic interaction is modeled via its constituent partons, whose number is a parameter, with best description obtained with four partons per nucleon. We fit directly the experimental multiplicity distributions (histograms), using {\it the same model parameters} for each reaction. The fit is performed in the c=1--80 centrality range. Avoiding the most peripheral events makes the method insensitive to the normalization issues caused by the difficulty in separating the Coulomb interactions, whereas the most central collisions may involve a different particle production mechanism. We find a proper model description of multiplicity distributions across all the studied systems for .

    ↳ nucl-thhep-phnucl-ex0 citations
  6. 06

    Two-dimensional Optical Parallel-Plate Avalanche Counter (OPPAC) with SiPM optical readout for heavy-ion tracking

    Yassid Ayyad🇪🇸 · Cristina Cabo🇪🇸 · Marco Cortesi

    We report the progress achieved on the development of a two-dimensional Optical Parallel-Plate Avalanche Counter (OPPAC) prototype for heavy-ion tracking. The device consists of two uniform thin parallel plates of 10 x 10 cm2 effective area, separated by a gap of 3 mm. The gap is filled with Tetrafluoromethane (CF4) at low pressure (up to 50 Torr). By applying a voltage difference between parallel plates, a uniform electric field is established within the gap. Electroluminescence emission is produced during the electron avalanche triggered by a charged particle that crosses the gas gap. The light is detected by an optical readout comprising four arrays of collimated Silicon Photomultipliers (SiPMs) deployed around the gas gap. The position of the particles is reconstructed by processing the light signals collected by all the SiPMs by computing the center of gravity of the light distribution within the SiPM arrays. The SiPM signals are read out and processed by a data acquisition (DAQ) system based on the General Electronics for TPC (GET). Preliminary results from a test with an alpha-particle source and a 100 MeV/u 40Ca beam demonstrate a sub-millimetre intrinsic position resolution sigma_det = 0.7 mm) while preserving good linearity over the entire detector active area.

    ↳ physics.ins-detnucl-ex0 citations
  7. 07

    Quantifying the Information Gain from Future High-Precision Radius Measurements for Identifying Twin Neutron Stars

    Bao-An Li🇺🇸 · Xavier Grundler🇺🇸

    Twin neutron stars (NSs), characterized by identical gravitational masses but different radii, are among the most promising astrophysical signatures of a strong first-order hadron--quark phase transition in supradense matter. We investigate how increasingly precise NS radius measurements improve the Bayesian inference of twin-star observability using mock radius data for a canonical NS. Radius uncertainties are varied from the current level of about km to the km precision anticipated from future X-ray and gravitational-wave observations. We quantify the information gained using the posterior distribution of the maximum twin-star radius separation together with an analytical model of branch distinguishability and complementary information-theoretic measures based on the branch observational efficiency and the Shannon entropy. The combined analyses reveal three inference regimes: a prior-dominated regime for km, a rapid information-gain regime for km, and an information-saturation regime for km. These complementary analyses consistently indicate that radius measurements with a precision of about km already extract most of the information available for identifying twin NSs within the present Bayesian framework. Beyond establishing a quantitative observational benchmark for future high-precision radius measurements, this work provides a general Bayesian framework for quantifying the information gain from progressively more precise observations and identifying the point of diminishing scientific returns.

    ↳ astro-ph.HEastro-ph.GAastro-ph.SRnucl-ex+1PLB(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE