Tue·Mar 18, 2025Tuesday·March 18, 2025

1. 01*

   Measurement of the inhomogeneity of the KATRIN tritium source electric potential by high-resolution spectroscopy of conversion electrons from ${}^{83m}$Kr

   H. Acharya🇺🇸 · M. Aker🇩🇪 · D. Batzler🇩🇪 · A. Beglarian🇩🇪 · J. Beisenkötter🇩🇪 · M. Biassoni🇮🇹 · B. Bieringer🇩🇪 · Y. Biondi🇩🇪 · F. Block🇩🇪 · B. Bornschein🇩🇪 · L. Bornschein🇩🇪 · M. Böttcher🇩🇪 and 121 other authors

   Precision spectroscopy of the electron spectrum of the tritium $\beta$-decay near the kinematic endpoint is a direct method to determine the effective electron antineutrino mass. The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to determine this quantity with a sensitivity of better than 0.3eV (90% C.L.). An inhomogeneous electric potential in the tritium source of KATRIN can lead to distortions of the $\beta$-spectrum, which directly impact the neutrino-mass observable. This effect can be quantified through precision spectroscopy of the conversion-electrons of co-circulated metastable ${}^{83m}$Kr. Therefore, dedicated, several-weeks long measurement campaigns have been performed within the KATRIN data taking schedule. In this work, we infer the tritium source potential observables from these measurements, and present their implications for the neutrino-mass determination.

   nucl-exhep-exEPJC(2025)·5 citations
2. 02*

   NNPDFpol2.0: a global determination of polarised PDFs and their uncertainties at next-to-next-to-leading order

   Juan Cruz-Martinez🇨🇭 · Toon Hasenack🇳🇱 · Felix Hekhorn🇫🇮 · Giacomo Magni🇳🇱 · Emanuele R. Nocera🇮🇹 · Tanjona R. Rabemananjara🇳🇱 · Juan Rojo🇳🇱 · Tanishq Sharma🇮🇹 · Gijs van Seeventer🇳🇱

   We present NNPDFpol2.0, a new set of collinear helicity parton distribution functions (PDFs) of the proton based on legacy measurements of structure functions in inclusive neutral-current longitudinally polarised deep-inelastic scattering (DIS), and of W -boson, single-inclusive, and di-jet production asymmetries in longitudinally polarised proton-proton collisions. The determination is accurate to next-to-next-to-leading order in the strong coupling, and includes heavy quark mass corrections in the analysis of DIS data. Uncertainties due to missing higher-order corrections are systematically incorporated by means of a covariance matrix determined by scale variations. NNPDFpol2.0 is based on a machine learning methodology, that makes use of Monte Carlo sampling for the representation of uncertainties into PDFs, of a neural network for the parametrisation of PDFs, of stochastic gradient descent for the optimisation of PDF parameters, and of hyperoptimisation for the selection of the best fitting model. We study the impact on PDFs of higher-order corrections, of the positivity constraint, and of the data. We demonstrate two phenomenological applications of NNPDFpol2.0, specifically the determination of the proton spin fraction carried by gluons and quarks, and of theoretical predictions for single-hadron production in longitudinally polarised DIS and proton-proton collisions.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2025)·37 citations
3. 03*

   The $\varphi NN,J/\psi NN,{\eta }_{c}NN$ systems based on HAL QCD interactions

   Liang-Zhen Wen🇨🇳 · Yao Ma🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳

   We investigate the existence of bound states and resonances in the $\varphi NN,J/\psi NN,{\eta }_{c}NN$ systems using HAL QCD interactions for $\varphi N,J/\psi N$, and ${\eta }_{c}N$. We employ the Gaussian expansion method to solve the complex-scaled Schrödinger equation and find no resonances or bound states in the $J/\psi NN$ and ${\eta }_{c}NN$ systems. We estimate the interaction between charmonium and nuclei, concluding that the $J/\psi$ or ${\eta }_c$ is likely to bind with ${}^3\mathrm{H}$, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, and heavier nuclei. For the $\varphi NN$ system, the lattice QCD $\varphi N\left({}^2{S}_{1/2}\right)$ interaction is absent. We combine the $\varphi p$ correlation function analysis and HAL QCD results in Model A. We assume the spin-spin interactions for $J/\psi N$ and $\varphi N$ systems are inversely proportional to their masses in Model B. Model A predicts a stronger $\varphi N({}^2{S}_{1/2})$ interaction and permits a two-body bound state, whereas Model B suggests the interaction is attractive but too weak to form a bound state. Both models predict bound states for the $I(J^P)=0(0^{-})$ and $0(1^{-})$ $\varphi NN$ systems. In Model A, these states are deeply bound with binding energies exceeding 15 MeV and remain existent when considering parameter uncertainties. In contrast, these states are very loosely bound in Model B, with binding energies below 1 MeV and an existent probability of about 60\% when parameter uncertainties are considered. In both models, there exist very loosely bound $I(J^P)=0(2^{-})$ three-body states which resemble a $\varphi$-d atom with the $\varphi$ meson surrounding the deuteron, but their existences are sensitive to parameter uncertainties. No bound states or resonances are found in the isovector $I(J^P)=1(1^{-})$ $\varphi NN$ system.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2025)·13 citations
4. 04*

   Quantification of the evaporation process during fragmentation of space-relevant nuclei on elemental targets

   Sukhendu De🇮🇳 · V. Choudhary · R. Chatterjee🇮🇳 · W. Horiuchi🇯🇵

   This study examines charge-changing cross sections for 12C, 14N, 16O, and 20Ne projectiles on elemental targets (C, Al, Cu) at a beam energy of around 290 MeV/nucleon. The two-stage abrasion-ablation model is used, with the abrasion stage described via the Glauber model, incorporating validated single-nucleon density distributions from proton elastic scattering data. In the ablation stage, where particle evaporation occurs, the contribution to charge-changing cross sections is estimated using two approaches. First, a statistical decay model is employed to analyze the evaporation of protons following neutron removal in the abrasion stage. The second approach estimates evaporation contributions by subtracting the direct process component (abrasion) from the experimental charge-changing cross section data. A comparison between these estimated contributions from the experimental data and the predictions of the statistical model enables a systematic evaluation of the evaporation process. The key factors influencing evaporation, such as excitation energy distribution parameters, decay width of the emitted particles, and nucleon separation energies, are analyzed. A strong correlation is observed between the maximum excitation energy available for evaporation and the neutron separation energy of the projectiles across different targets, highlighting the role of evaporation dynamics in the charge-changing cross sections.

   ↳ nucl-thnucl-exPRC(2025)·0 citations
5. 05*

   Effect of transverse momentum conservation and flow on symmetric cumulants $s{c}_{2,3}\left\{4\right\}$ and $s{c}_{2,3,4}\left\{6\right\}$

   Jia-Lin Pei🇨🇳 · Guo-Liang Ma🇨🇳 · Adam Bzdak🇵🇱

   Symmetric cumulants can improve our understanding of the joint probability distribution function $P\left(v_m,v_n,v_k,\dots ,{\Psi }_m,{\Psi }_n,{\Psi }_k,\dots \right)$, potentially offering new insights into the nature of the fluctuations of the quark-gluon plasma produced in relativistic heavy-ion collisions. In this work, the four-particle symmetric cumulants $s{c}_{2,3}\left\{4\right\}$, six-particle symmetric cumulants $s{c}_{2,3,4}\left\{6\right\}$, and the normalized cumulants $ns{c}_{2,3}\left\{4\right\}$ and $ns{c}_{2,3,4}\left\{6\right\}$ originating from transverse momentum conservation, collective flow, and the interplay between the two effects are calculated. Our results on $s{c}_{2,3}\left\{4\right\}$ are consistent with the ATLAS data using the subevent cumulant method, facilitating a more profound understanding of the origins of the symmetric cumulant in small systems. Our results on $s{c}_{2,3,4}\left\{6\right\}$ serve as theoretical predictions for future experimental measurements in small systems.

   ↳ nucl-thhep-phnucl-exPRC(2025)·3 citations
6. 06*

   Spectral properties and spin alignment of $\varphi$ meson in QCD Matter

   Zhong-Yuan Sun🇨🇳 · You-Yu Li🇨🇳 · Shuai Y. F. Liu🇨🇳

   As the spin alignment of a vector meson is predicted to be correlated with its spectral properties, we study the spectral properties of the $\varphi$ meson using two microscopic Lagrangians based either on chiral effective field theory or the quark-meson model. We calculate the self-energies and spectral functions of the $\varphi$ meson for these two Lagrangians at the one-loop level within the Matsubara formalism of finite-temperature quantum field theory, employing various parameters to represent different physical scenarios. Using these spectral functions, transport coefficients related to the spin alignment and tensor polarization are obtained, connecting the spin alignment of the $\varphi$ meson to hydrodynamic gradients. Using the standard freeze-out picture within the relativistic hydrodynamic model, we explore how the possible pattern of the spin alignment can be generated using these microscopically calculated spectral functions. We discover that, with certain assumptions, these simple microscopic model-based calculations can produce sizable spin alignments with a sign-flipping behavior in their $p_T$ and centrality dependence, similar to those observed in experiments.

   ↳ nucl-thhep-phhep-thnucl-ex2 citations
7. 07*

   Key Historical Experiments in Hadron Physics

   Claude Amsler🇦🇹

   The experimental observations that led to the development of hadron physics are reviewed with emphasis on the discoveries of mesons and baryons, starting in the 1940s with the pion and kaon which mediate the strong hadronic force. The evidence for an internal structure consisting of two or three elementary spin 1/2 particles will be reviewed. In 2003 more complex multi-quark hadrons began to emerge. The subsequent developments beyond the early 2000s are covered in the Review of Particle Physics (Int. J. Mod. Phys. A 41 (2026) 2630011). Given the large number of hadrons, the choice of key experiments is somewhat subjective.

   ↳ physics.hist-phhep-exnucl-exEncyclopedia of Particle Physics 2026 (1s…·3 citations
8. 08*

   Nuclear Physics at BRIF

   Wei Nan · Bing Guo · Jie Chen · Baoqun Cui · Wei Fu · Xianlu Jia · Chaoxin Kan · Jiayinghao Li · Yunju Li · Chengjian Lin🇨🇳 · Yihui Liu · Nanru Ma and 13 other authors

   The Beijing Radioactive Ion-beam Facility (BRIF), which is based on Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60 to 300 keV, and post-accelerated beams in the energy range from 3 to 10 MeV/u for nuclei with mass numbers of A < 80 by Isotope Separation On-Line (ISOL) technique. For nuclei with A up to 170, energies are still able to reach 3 MeV/u. This facility offers opportunities to address key questions of current interest in nuclear astrophysics, nuclear structure and reactions of unstable nuclei. In this review we present a comprehensive introduction to the BRIF and the typical experimental instruments installed on it, and then summarize current experimental results on unstable Na and Rb isotopes and future plan for further development of the BRIF to improve its performance.

   ↳ physics.acc-phnucl-exPPNP(2025)·7 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.