PaperPanorama

Nuclear Experiment·nucl-ex

Fri·Jul 31, 2026

5 papers—1 primary·4 cross-listed

All5Primary1Cross-lists4
  1. 01

    Probing (Hyper)Nuclei Wave Functions and Production Mechanisms in GeV Isobar Collisions at RHIC

    STAR Collaboration

    The study of nuclei and hypernuclei production is a powerful tool to investigate the formation mechanism of loosely bound states in high-energy heavy-ion collisions. A key prediction from coalescence models is a strong suppression of the hypertriton () compared to production in small collision systems due to the larger radius of . In this letter, the STAR collaboration reports measurements on (hyper)nuclei () production at mid-rapidity in Ru+Ru and Zr+Zr collisions at GeV as a function of collision centrality. We find that the ratios and deviate significantly from thermal model expectations. Coalescence calculations incorporating realistic non-Gaussian wave functions for the and provide an improved description of the data, while Gaussian descriptions of the wave function fail to simultaneously reproduce the measured and the binding energy of . These results suggest that the wave function contains larger short-distance -- probability than implied by a Gaussian ansatz, demonstrating the potential of heavy-ion production measurements as a probe of hypernuclear wave functions and the underlying hyperon--nucleon interaction.

    nucl-exhep-exhep-phnucl-th1 citation
  2. 02

    Photon-calibrated event-activity bias and subcollision geometry in d+Au collisions at = 200 GeV with PYTHIA 8 Angantyr

    Muhammad Ajaz🇸🇦 · Haifa I. Alrebdi🇸🇦 · Muhammad Waqas🇨🇳

    Event-activity selections in small nuclear collision systems couple collision geometry to the soft response accompanying a hard scattering. We examine this coupling in d+Au collisions at = 200 GeV with PYTHIA 8.316 Angantyr, using direct photons, terminal pre-decay neutral pions, and anti-kT jets. A hard-bias factor compares the probability for a hard event to enter an activity class with an -weighted minimum-bias reference. The model predicts a depleted most-active class and an enhanced peripheral class for both photons and pions. Photon-tagged events also sample a smaller mean impact parameter and more nondiffractive subcollisions than pion-tagged or inclusive HardQCD events. Comparing fully correlated Angantyr events with an Ncoll-reweighted minimum-bias reference and a factorized diagnostic separates the explicit geometric contribution from residual hard-soft correlations. STAR-like and PHENIX-like particle-level activity proxies preserve the class ordering but give different class probabilities. The calculation is generator-level and does not identify a unique microscopic origin for the residual correlations.

    ↳ hep-phnucl-exnucl-th0 citations
  3. 03

    Unbiased Data-Driven Determination of the Nuclear Dipole Amplitude in the Color Glass Condensate

    Si-Wei Dai🇨🇳 · Haowu Duan🇨🇳 · Long-Gang Pang🇨🇳 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇨🇳 · Han-Zhong Zhang🇨🇳 · Wenbin Zhao🇨🇳

    Gluon saturation limits the growth of parton densities at small Bjorken- and is expected to be most pronounced in heavy nuclei. Yet quantitative extractions of the nuclear gluon dipole amplitude have long relied on parametrized initial conditions, introducing uncontrolled model dependence that obscures genuine nuclear effects. We introduce a physics-informed neural-network framework that embeds the collinearly improved Balitsky-Kovchegov evolution equation directly into the training objective, allowing the impact-parameter-averaged dipole amplitude to be determined from data without assuming a functional form for its initial condition. Applying this framework to forward-hadron nuclear-modification-factor and coherent photoproduction data, we extract the Pb dipole amplitude at with QCD evolution and momentum-space positivity enforced throughout training. The evolved amplitude reproduces the measured cross sections across the available kinematic range and yields a saturation-scale ratio , consistent with simple geometric scaling. The extracted Pb initial condition is well described by a McLerran-Venugopalan-type form, in contrast to the proton, reflecting the higher color-charge density of a large nucleus. Using the same amplitude, we predict the rapidity dependence of the transverse-momentum ratio in , Pb, and Pb collisions, finding agreement with recent LHCb measurements at low multiplicity without any system-dependent parameters. This work provides the first unbiased, data-driven determination of nuclear structure in the saturation regime and establishes a general strategy for embedding nonlinear evolution equations into machine-learning extractions of dynamically constrained observables.

    ↳ hep-phnucl-exnucl-th3 citations
  4. 04

    On a Liquid Krypton TPC for double positron decay searches

    S. Torelli🇪🇸 · A. Simón Estévez🇪🇸 · F. Monrabal Capilla🇪🇸

    Double positron decay features the emission of four 511 keV gamma rays from positron alongside the well-known 'double blob' signature which can be tracked with a TPC. Successfully detecting these gammas creates a unique signature that cannot be replicated by any background radiation. This enables a virtually background-free search if the four gammas are efficiently tagged. In this work, we propose the concept of a liquid Krypton Time Projection Chamber designed to search for double positron decay using this four-gamma tagging concept, and we'll show how already a small version of this prototype could set the world best limit on the search of this decay towards a sensitivity of y with a ton scale detector.

    ↳ physics.ins-detnucl-ex0 citations
  5. 05

    Extraction of for Proton, Neutron, Deuteron and He from Quasi-real Photon Scattering

    YiLei Li🇺🇸 · B.Callahan🇺🇸 · M.M.Dalton🇺🇸 · A.Deur🇺🇸 · O.Larson🇺🇸 · A.Rask🇺🇸 · D.W.Upton🇺🇸 · X.Zheng🇺🇸

    We report on an extraction of the polarized photoproduction cross-section for the proton, deuteron, neutron and He, obtained by extrapolating electron scattering data to the real photon point. The data are from the Jefferson Lab E97-110 (He) and CLAS EG4 (proton and deuteron) experiments. Information on the neutron is extracted from the deuteron or He data using the weak binding approximation. Comparing with data obtained with real photons, we find that while the proton results agree, our results on the deuteron and the neutron exhibit a larger strength in the region, and are more consistent with isospin symmetry when compared with the proton results.

    ↳ hep-exnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE