Tue·Oct 29, 2024Tuesday·October 29, 2024

1. 01*

   Estimation of Ru-97 Half-Life Using the Most Frequent Value Method and Bootstrapping Techniques

   Victor V. Golovko

   A new and robust statistics was applied to previous measurements of the 97Ru half-life. This process incorporates the most frequent value (MFV) technique along with hybrid parametric bootstrap (HPB) method to deliver a more precise estimate of the 97Ru half-life. The derived value is T1/2,MFV(HPB) = 2.8385+0.0022-0.0075 days. This estimate corresponds to a 68.27% confidence interval ranging from 2.8310 to 2.8407 days, and a 95.45% confidence interval ranging from 2.8036 to 2.8485 days, calculated using the percentile method. This level of uncertainty is significantly lower-over 30 times-than the uncertainty in the previously recognized half-life value found in nuclear data sheets. Employing an alternate approach to minimization could further cut down the statistical uncertainty by 44% for the 97Ru half-life. In particular, the HPB method accounts for uncertainties in small datasets when determining the confidence interval. When the HPB method, in combination with the MFV approach, was used to review a four-element dataset of the specific activity of 39Ar based on underground data, the result was SA_MFV(HPB) = 0.966 +0.027 -0.020 Bq/kg_atmAr. This value results in a 68.27% confidence interval of 0.946 to 0.993, along with a 95.45% confidence interval of 0.921 to 1.029, also determined using the percentile method.

   ↳ physics.data-annucl-ex5 citations
2. 02*

   Medium recoil mode of $\Delta$ production in single isobaric charge-exchange reactions

   Xin Lei🇨🇳 · Erxi Xiao🇨🇳 · Yingge Huang🇨🇳 · Yujie Feng🇨🇳 · Hui Wang🇨🇳 · Jiali Huang🇨🇭 · Fuchang Gu🇨🇳 · Long Zhu🇨🇳 · Jun Su🇨🇳

   The dynamic mechanisms underlying single charge-exchange reactions have been investigated using a theoretical framework that combines the Isospin-dependent Quantum Molecular Dynamics (IQMD) model with the statistical decay model GEMINI++. Two distinct channels contribute to the single isobaric charge-exchange reaction: quasi-elastic channel, where neutron-proton scattering drives the charge-exchange, and inelastic channel, where the $\Delta$ particle is produced during the process. In a referenced study [Phys.RevC 106.014618(2022)], experimental data have revealed that the inelastic channel accounts for approximately 50 percent of the single isobaric charge-exchange reaction. However, our current model fails in reproducing the significant contribution of inelastic channel unless the novel medium recoil mode associated with $\Delta$ production is considered in the calculations. Notably, this in-medium effect arising from inelastic nucleon-nucleon collisions is not yet incorporated into mainstream microscopic transport models. The dynamical properties of protons and pions emitting in the single isobaric charge-exchange reactions are predicted. This exploration of in-medium effects adds a valuable dimension to our understanding of the intricate dynamics involved in single charge-exchange reactions.

   ↳ nucl-thnucl-ex0 citations
3. 03*

   Particle Identification with the ePIC detector at the EIC

   Chandradoy Chatterjee (on behalf of the ePIC collaboration)🇮🇹

   The ePIC detector is being designed as a general-purpose detector to deliver the full physics program of the Electron-Ion Collider (EIC) in BNL USA. Particle Identification (PID) plays a crucial role in the EIC physics program. Over a wide phase-space the PID systems provide excellent hadron identification required for the EIC physics program. Additionally, the PID systems have to provide low momentum electron-pion separation to support the calorimeter performance. The ePIC experiment employs different advanced PID technologies to reach the physics goals. The compact set-up the collider and the presence of high magnetic field of the experimental solenoid impose numerous technical challenges. In this article we will describe the PID subsystems of the ePIC detector, with a specific emphasis on high momentum PID system using RICH technology. The article will report about the studies performed with SiPMs as the photo-sensor candidate for forward RICH detector. Also, studies made with novel LAPPD detectors and standard MCP- PMTs chosen as baseline photo-sensor candidates for the backward RICH and barrel DIRC system respectively. This article will include a discussion on the simulation studies made with stand-alone Geant4 simulations and official ePIC software framework.

   ↳ physics.ins-dethep-exnucl-exPoS(2025)·11 citations
4. 04*

   Fluctuations and correlations of quark spin in hot and dense QCD matter

   Hao-Lei Chen🇨🇳 · Wei-jie Fu🇨🇳 · Xu-Guang Huang🇨🇳 · Guo-Liang Ma🇨🇳

   In this work, we examine the impact of QCD phase transitions on the quark spin fluctuations and correlations. We propose the quark-antiquark correlation, which relates to the vector meson spin alignment and the $\Lambda -\bar{\Lambda }$ correlation, can be used as a novel probe of the critical end point (CEP) in the QCD phase diagram. Using the Nambu-Jona-Lanisio model, we qualitatively study the properties of quark-antiquark spin correlations. Our findings reveal a peak structure near the CEP of the chiral phase transition, which may serve as an experimental signature of the CEP and account for the non-monotonic behavior of $\varphi$ meson alignment at low collision energies observed recently in experiments.

   ↳ hep-phnucl-exnucl-thPRL(2025)·22 citations
5. 05*

   Elastic Dijet Production in Electron Scattering on a Longitudinally Polarized Proton at Small $x$: A Portal to Orbital Angular Momentum Distributions

   Yuri V. Kovchegov🇺🇸 · Brandon Manley🇺🇸

   We calculate the elastic production of dijets from electron collisions with a longitudinally polarized proton target at small values of the Bjorken $x$ variable. Building on the pioneering proposals of \cite{Hatta:2016aoc,Bhattacharya:2022vvo, Bhattacharya:2023hbq, Bhattacharya:2024sck} for measuring the quark and gluon orbital angular momentum (OAM) distributions, our focus is on both the longitudinal double spin asymmetry (DSA) and longitudinal single spin asymmetry (SSA). We compute the numerators of these asymmetries in the small-$x$ formalism of the light-cone operator treatment. Utilizing the small-$x$ expressions for the OAM distributions derived in our earlier paper, we demonstrate that the DSA provides a robust probe for both the quark and gluon OAM distributions within the proton. In contrast, we find that while the SSA is also sensitive to the OAM distributions, extraction of the latter from the SSA would require new developments in small-$x$ theory and phenomenology, and is probably not feasible at this point in time. These findings highlight the potential of DSA measurements in elastic dijet production at the future Electron-Ion Collider to provide the first-ever direct access to the quark and gluon OAM distributions at small $x$, paving the way for new insights into the proton spin puzzle.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2025)·16 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.