Tue·Jul 1, 2025Tuesday·July 1, 2025

1. 01*

   Sensitivity of nEXO to ${}^{136}$Xe Charged-Current Interactions: Background-free Searches for Solar Neutrinos and Fermionic Dark Matter

   G. Richardson · B. G. Lenardo · D. Gallacher · R. Saldanha · P. Acharya · S. Al Kharusi · A. Amy · E. Angelico · A. Anker · I. J. Arnquist · A. Atencio · J. Bane and 126 other authors

   We study the sensitivity of nEXO to solar neutrino charged-current interactions, ${\nu }_e{+}^{136}$Xe${\to }^{136}$Cs${}^{\ast }+e^{-}$, as well as analogous interactions predicted by models of fermionic dark matter. Due to the recently observed low-lying isomeric states of ${}^{136}$Cs, these interactions will create a time-delayed coincident signal observable in the scintillation channel. Here we develop a detailed Monte Carlo of scintillation emission, propagation, and detection in the nEXO detector to model these signals under different assumptions about the timing resolution of the photosensor readout. We show this correlated signal can be used to achieve background discrimination on the order of $10^{-9}$, enabling nEXO to make background-free measurements of solar neutrinos above the reaction threshold of 0.668 MeV. We project that nEXO could measure the flux of CNO solar neutrinos with a statistical uncertainty of 25%, thus contributing a novel and competitive measurement towards addressing the solar metallicity problem. Additionally, nEXO could measure the mean energy of the ${}^7$Be neutrinos with a precision of $\sigma \le 1.5$ keV and could determine the survival probability of ${}^7$Be and $pep$ solar ${\nu }_e$ with precision comparable to state-of-the-art. These quantities are sensitive to the Sun's core temperature and to non-standard neutrino interactions, respectively. Furthermore, the strong background suppression would allow nEXO to search for for charged-current interactions of fermionic dark matter in the mass range $m_{\chi }$ = $0.668$-$7$ MeV with a sensitivity up to three orders of magnitude better than current limits.

   nucl-exhep-exphysics.ins-detPRD(2025)·2 citations
2. 02*

   Fundamental Nuclear and Particle Physics At Neutron Sources

   H. Abele · J. Amaral · W.R. Anthony · L. AAstrand · M. Atzori Corona · S. Baessler · M. Bartis · E. Baussan · D. H. Beck · J. Bijnens · K. Bodek · J. Bosina and 112 other authors

   Fundamental neutron and neutrino physics at neutron sources, combining precision measurements and theory, can probe new physics at energy scales well beyond the highest energies probed by the LHC and possible future high energy collider facilities. The European Spallation Source (ESS) will in the not too far future be a most powerful pulsed neutron source and simultaneously the world's brightest pulsed neutrino source. The ESS, and neutron sources in general, can provide unprecedented and unique opportunities to contribute to the search for the missing elements in the Standard Model of particle physics. Currently there are no strong indications where hints of the origin of the new physics will emerge. A multi-pronged approach will provide the fastest path to fill the gaps in our knowledge and neutron sources have a pivotal role to play. To survey the ongoing and proposed physics experiments at neutron sources and assess their potential impact, a workshop was held at Lund University in January, 2025. This report is a summary of that workshop and has been prepared as input to the European Strategy Update.

   nucl-exhep-ex5 citations
3. 03*

   Energy-energy correlators in small and large systems

   Beatrice Liang-Gilman (on behalf of the ALICE Collaboration)🇺🇸

   Energy-energy correlators (EECs) provide a powerful tool to study the evolution of scattered partons into final-state hadrons. In these proceedings, a variety of energy correlator measurements performed by the ALICE collaboration are reported. The 2-point energy-energy correlator (EEC) is measured in inclusive jets and heavy-flavor jets in pp collisions, as well as in inclusive jets in p-Pb collisions. The 3-point energy correlator is also discussed, including prospects for its use in extracting the strong coupling constant.

   nucl-ex6 citations
4. 04*

   Direct proton transfer on ${}^{46}$Ar supports the presence of a charge density bubble linked to a novel nuclear structure below ${}^{48}$Ca

   Daniele Brugnara (1,2)🇮🇹 · Andrea Gottardo (2)🇮🇹 · Marlene Assiè (3)🇫🇷 · Carlo Barbieri (4,5)🇮🇹 · Daniele Mengoni (1,6)🇮🇹 · Didier Beaumel (3)🇫🇷 · Stefano Brolli (4,5)🇮🇹 · Simone Bottoni (4,5)🇮🇹 · Emmanuel Clément (7)🇫🇷 · Gianluca Colò (4,5)🇮🇹 · Freddy Flavigny (8)🇫🇷 · Franco Galtarossa (3,6)🇫🇷 and 67 other authors

   The ${}^{46}$Ar(${}^3$He,d)${}^{47}$K reaction was performed in inverse kinematics using a radioactive ${}^{46}$Ar beam produced by the SPIRAL1 facility at GANIL and a cryogenic ${}^3$He target. The AGATA-MUGAST-VAMOS setup allowed the coincident measurement of the $\gamma$ rays, deuterons and recoiling ${}^{47}$K isotopes produced by the reaction. The relative cross sections towards the proton-addition states in ${}^{47}$K point towards a depletion of the $\pi s_{1/2}$ shell. The experimental findings are in good agreement with ab initio calculations, which predict that ${}^{46}$Ar exhibits a charge density bubble associated with a pronounced proton closed-shell character.

   nucl-exnucl-th1 citation
5. 05*

   Investigation of the performance of a GNN-based b-jet tagging method in heavy-ion collisions

   Changhwan Choi🇰🇷 · Sanghoon Lim🇰🇷

   Beauty-tagged jets (b-jets)-collimated sprays of particles originating from the fragmentation of beauty quarks produced in the initial hard scatterings-provide a unique probe of parton dynamics in the quark-gluon plasma (QGP) created in ultrarelativistic heavy-ion collisions. In particular, energy loss patterns of low-$p_T$ b-jets traversing the QGP offer valuable insight into the strong interaction in its nonperturbative regime. CMS and ATLAS Collaborations at the LHC have studied b-jet production in Pb-Pb collisions. The results were limited to a high-$p_T$ region, because a major challenge at low-$p_T$ is the overwhelming number of background particles from QGP hadronisation, which severely hinders the effectiveness of conventional b-jet tagging techniques. To enable precise measurements in such complex environments, advanced tagging methods are required. Graph Neural Networks (GNNs), capable of learning relational structures among jet constituents, represent a promising deep learning approach for b-jet identification. In this study, we adopt and adapt the GN1 model, initially developed by ATLAS, for use in Pb-Pb collision environments. We investigate the model's performance by applying it to jets embedded with Pb-Pb background particles, evaluating both tagging decisions and robustness against background contamination. This work presents a comprehensive evaluation of GNN-based b-jet tagging under heavy-ion collision conditions, aiming to advance future precision studies of QGP-induced partonic energy loss.

   ↳ physics.data-annucl-exJ.Phys.G(2026)·0 citations
6. 06*

   Elliptic flow of charged hadrons in d+Au collisions at $\sqrt{s_{NN}}=$ 200 GeV using a multi-phase transport model

   Jaideep Tanwar🇮🇳 · Ishu Aggarwal🇮🇳 · Vipul Bairathi🇨🇱 · Lokesh Kumar🇮🇳 · Sonia Kabana🇨🇱

   This study presents a comprehensive analysis of the elliptic flow coefficient, $v_2$, for charged hadrons at mid-rapidity in d+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$. Utilizing the AMPT model in both default and string melting modes, we examine the dependence of $v_2$ on transverse momentum, collision centrality, and particle type. Furthermore, we present $v_2$ scaled by participant eccentricity, which indicates a similar level of collectivity across different centrality intervals in d+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$ within the AMPT-SM model. Our results indicate that the early-stage partonic phase significantly influences $v_2$, as observed by variations in parton scattering cross-section, while the later stage hadronic rescattering shows minimal impact. Comparisons with STAR and PHENIX experimental data show that the AMPT model effectively captures the transverse momentum dependence of $v_2$, underlining the importance of parton scattering mechanisms and the need for careful interpretation of experimental results in asymmetric systems.

   ↳ nucl-thhep-phnucl-exPRC(2026)·0 citations
7. 07*

   Half-life of ${}^{136}$Xe for neutrinoless double-$\beta$ decay calculated with effective axial-vector current coupling unified for two-neurtino and neutrinoless double-$\beta$ decay modes

   J. Terasaki🇨🇿 · O. Civitarese🇦🇷

   The upper limit on the mass of the Majorana neutrino, extracted from the limits on the nonobservation of the neutrinoless double-$\beta$ ($0\nu \beta \beta$) decay, is hampered by uncertainties in the matrix elements of the transition operators. Recently, we have shown that the values of the effective axial-vector current coupling constants ($g_A^{\text{eff}}$) for the $0\nu \beta \beta$ and the two-neutrino double-$\beta$ decays are close. This striking result was obtained for the first time by including vertex corrections and two-body currents in these matrix elements. In this letter, we calculate the half-life for the $0\nu \beta \beta$ decay ($T_{1/2}^{0\nu }$) of ${}^{136}$Xe using this closeness and show the convergence of the half-life with respect to the variation of the method to determine $g_A^{\text{eff}}$. The closeness of the $g_A^{\text{eff}}$ of the two decay modes plays a decisive role in predicting $T_{1/2}^{0\nu }$. The appropriate value of $g_A^{\text{eff}}$ depends on the assumptions made for the sectors of the nuclear structure and transition operators of the calculations within the perturbation scheme. The value $g_A^{\text{eff}}\approx 1$ is obtained when the SkM${}^{\ast }$ is used to describe the nuclear structure component, while a smaller value of $g_A^{\text{eff}}$ is obtained by applying a less realistic interaction like the SGII one.

   ↳ nucl-thnucl-exPRC(2025)·1 citation
8. 08*

   Quark Recombination

   Rainer J. Fries🇺🇸 · Vincenzo Greco🇮🇹 · Ralf Rapp🇺🇸

   Hadronization is a fundamental process occurring at a distance scale of about $1\mathrm{fm}\simeq {\mathrm{\Lambda }}_{\mathrm{QCD}}^{-1}$, hence within non-perturbative dynamics. In elementary collisions, like $e^{+}{e}^{-}$, $e^{-}p$, or $pp$, phenomenological approaches to hadronization have been developed based on vacuum-like dynamics that require the creation of quark-antiquark and/or diquark pairs during the hadronization process. In the 2000s, the idea was developed that in ultra-relativistic nucleus-nucleus (AA) collisions, which lead to the formation of a partonic medium with large (anti-)quark densities, hadronization can occur through the recombination of in-medium quarks, unlike the situation in $e^{+}{e}^{-}$, $e^{-}p$, and $pp$. We give an overview of the main features that characterize quark recombination and have enabled a description of several important experimental observables at both RHIC and LHC over the last two decades. We highlight some additional developments and open issues. We specifically discuss the impact of coalescence on the study of heavy-flavor hadronization, including recent developments showing signatures of (the onset of) quark coalescence even in $pp$ collisions at TeV energies. Furthermore, we highlight specific features of hadronization for quarkonium in AA collisions, where it has been possible to develop a dynamical kinetic approach that allows to extract more detailed information about the temperature dependence of the heavy-quark interaction in hot QCD matter.

   ↳ hep-phhep-exnucl-exnucl-th6 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.