Thu·Dec 19, 2024Thursday·December 19, 2024

1. 01*

   Model-independent measurement of isospin diffusion in Ni-Ni systems at intermediate energy

   C. Ciampi🇫🇷 · J. D. Frankland🇫🇷 · D. Gruyer🇫🇷 · N. Le Neindre🇫🇷 · S. Mallik🇮🇳 · R. Bougault🇫🇷 · A. Chbihi🇫🇷 · L. Baldesi🇮🇹 · S. Barlini🇮🇹 · E. Bonnet🇫🇷 · B. Borderie🇫🇷 · A. Camaiani🇮🇹 and 29 other authors

   In this work we provide a model-independent experimental evaluation of the degree of isospin equilibration taking place in ${}^{58,64}$Ni+${}^{58,64}$Ni collisions at 32 MeV/nucleon across varying reaction centralities. This result has been obtained by combining the complementary information provided by two different datasets, sharing common characteristics. The first dataset has been acquired with the INDRA setup and has been used to implement a model-independent reconstruction of the impact parameter. The second dataset has been acquired in the first experimental campaign of the coupled INDRA-FAZIA apparatus at GANIL. The neutron-to-proton content of the quasiprojectile remnant measured by FAZIA has been employed as isospin observable. The effect of isospin diffusion has been evidenced by means of the isospin transport ratio, reported as a function of the impact parameter of the collision. The evolution towards isospin equilibration from semiperipheral to more central collisions is clearly extracted. This experimental result, expanding our previous works (Phys. Rev. C 106, 024603 (2022) and Phys. Rev. C 108, 054611 (2023)), can be compared with the predictions of any transport model, and can thus be used to set constraints on the behavior of the symmetry energy term of the nuclear Equation of State at sub- to saturation densities.

   nucl-exPRC(2025)·7 citations
2. 02*

   Searching for Neutrinoless Double-Beta Decay of ${}^{136}$Xe with PandaX-4T

   PandaX Collaboration: Shu Zhang🇨🇳 · Zihao Bo🇨🇳 · Wei Chen🇨🇳 · Xun Chen🇨🇳 · Yunhua Chen🇨🇳 · Zhaokan Cheng🇨🇳 · Xiangyi Cui🇨🇳 · Yingjie Fan🇨🇳 · Deqing Fang🇨🇳 · Zhixing Gao🇨🇳 · Lisheng Geng🇨🇳 · Karl Giboni🇨🇳 and 89 other authors

   We report the search for neutrinoless double-beta decay of ${}^{136}$Xe from the PandaX-4T experiment with a 3.7-tonne natural xenon target. The data reconstruction and the background modeling are optimized in the MeV energy region. A blind analysis is performed with data from the commissioning run and the first science run. No significant excess of signal over the background is observed. A lower limit on the half-life of ${}^{136}$Xe neutrinoless double-beta decay is established to be $2.1\times 10^{24}$~yr at the 90\% confidence level, with a ${}^{136}$Xe exposure of 44.6~kg$\cdot$year. Our result represents the most stringent constraint from a natural xenon detector to date.

   nucl-exhep-exSci.Bull.(2025)·14 citations
3. 03*

   Dynamics of Hot QCD Matter 2024 -- Hard Probes

   Santosh K. Das · Prabhakar Palni · Amal Sarkar · Vineet Kumar Agotiya · Aritra Bandyopadhyay · Partha Pratim Bhaduri · Saumen Datta · Vaishnavi Desai · Debarshi Dey · Vincenzo Greco · Mohammad Yousuf Jamal · Gurleen Kaur and 15 other authors

   The hot and dense QCD matter, known as the Quark-Gluon Plasma (QGP), is explored through heavy-ion collision experiments at the LHC and RHIC. Jets and heavy flavors, produced from the initial hard scattering, are used as hard probes to study the properties of the QGP. Recent experimental observations on jet quenching and heavy-flavor suppression have strengthened our understanding, allowing for fine-tuning of theoretical models in hard probes. The second conference, HOT QCD Matter 2024, was organized to bring the community together for discussions on key topics in the field. This article comprises 15 sections, each addressing various aspects of hard probes in relativistic heavy-ion collisions, offering a snapshot of current experimental observations and theoretical advancements. The article begins with a discussion on memory effects in the quantum evolution of quarkonia in the quark-gluon plasma, followed by an experimental review, new insights on jet quenching at RHIC and LHC, and concludes with a machine learning approach to heavy flavor production at the Large Hadron Collider.

   nucl-exhep-exhep-phnucl-thIJMPE(2025)·8 citations
4. 04*

   Machine Learning-Assisted Measurement of Lepton-Jet Azimuthal Angular Asymmetries in Deep-Inelastic Scattering at HERA

   The H1 collaboration: V. Andreev (47) · M. Arratia (31)🇺🇸 · A. Baghdasaryan (43)🇦🇲 · A. Baty (8)🇺🇸 · K. Begzsuren (37)🇲🇳 · A. Bolz (15)🇩🇪 · V. Boudry (27)🇫🇷 · G. Brandt (14)🇩🇪 · D. Britzger (11)🇩🇪 · A. Buniatyan (6)🇬🇧 · L. Bystritskaya (47) · A.J. Campbell (15)🇩🇪 and 131 other authors

   In deep-inelastic positron-proton scattering, the lepton-jet azimuthal angular asymmetry is measured using data collected with the H1 detector at HERA. When the average transverse momentum of the lepton-jet system, $|{\vec{P}}_{\perp }|$, is much larger than the total transverse momentum of the system, $|{\vec{q}}_{\perp }|$, the asymmetry between parallel and antiparallel configurations, ${\vec{P}}_{\perp }$ and ${\vec{q}}_{\perp }$, is expected to be generated by initial and final state soft gluon radiation and can be predicted using perturbation theory. Quantifying the angular properties of the asymmetry therefore provides an additional test of the strong force. Studying the asymmetry is important for future measurements of intrinsic asymmetries generated by the proton's constituents through Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs), where this asymmetry constitutes a dominant background. Moments of the azimuthal asymmetries are measured using a machine learning method for unfolding that does not require binning.

   ↳ hep-exhep-phnucl-ex22 citations
5. 05*

   $2\nu \beta \beta$ Spectrum in Chiral Effective Field Theory

   Saad el Morabit🇳🇱 · Ryan Bouabid🇺🇸 · Vincenzo Cirigliano🇺🇸 · Jordy de Vries🇳🇱 · Lukáš Gráf🇳🇱 · Emanuele Mereghetti🇺🇸

   We investigate two-neutrino double beta decay ($2\nu \beta \beta$) in chiral effective field theory. We find contributions from weak magnetism and double-weak pion-exchange at next-to-leading-order in the chiral power counting. We discuss the impact of the chiral corrections on the electron spectra and find that they should be included in analyses of $2\nu \beta \beta$ decay that aim to uncover new physics signatures in the electron spectrum. We illustrate this point by revisiting the effect of sterile neutrinos and non-standard charged interactions. We also find that the pion-exchange contributions involve nuclear matrix elements that are related to those appearing in neutrinoless double beta decay ($0\nu \beta \beta$). We investigate whether the $0\nu \beta \beta$ nuclear matrix elements can be obtained from detailed measurements of the energy spectrum of the outgoing electrons in $2\nu \beta \beta$ transitions.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2025)·13 citations
6. 06*

   Experimental validation of the Gaseous Proton Recoil Telescope for quasi-absolute neutron flux measurements

   Carole Chatel (GSI, LP2I - Bordeaux) · Ludovic Mathieu (LP2I - Bordeaux) · Mourad Aïche (UB) · Abdel Rebii (LP2I - Bordeaux) · Hedi El Amami (LP2I - Bordeaux) · Benoît Dufort (LP2I - Bordeaux) · Maria Diakaki (UOA) · Olivier Bouland · Gilles Noguère

   The accuracy of neutronics simulations of actual or future reactor cores is nowadays driven by the precision of the nuclear data used as input. Among the most important neutron-induced fission cross sections to understand well are the actinides. It is, indeed, of primary importance to know accurately these cross sections around 1 MeV for the safety of Generation IV reactors. High accuracy measurements of neutron flux are essential for accurate cross section measurements; measurements of this flux with respect to the 1 H(n,n)p cross section can be made with the proton recoil technique. For an accurate measurement below 1 MeV, the Gaseous Proton Recoil Telescope (GPRT) is developed and characterized, with the aim to provide quasi-absolute neutron flux measurements with an accuracy better than 2%. This detector is composed of a double ionization chamber with a Micromegas segmented detection plane. The pressure of the gas can be adjusted to protons stopping range -and therefore to neutrons energy. An accurate neutron flux measurement requires that the GPRT has an intrinsic efficiency of 100%, and thus an important effort has been made to verify this. An alpha source and proton micro-beam have been used and the intrinsic efficiency is confirmed to be 100%. Additionally, the dead-time of the detector has been investigated on a test bench, and is found to be 7.3 ms.

   ↳ physics.ins-detnucl-exNuclear Instruments and Methods in Physic…
7. 07*

   Splitting the atom before the atom had been split

   Julyan H. E. Cartwright🇪🇸

   The history of the discovery of nuclear fission and how science fiction had anticipated it.

   ↳ physics.hist-phnucl-expublished November 2024 in Czech translat…·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.