Thu·Feb 6, 2025Thursday·February 6, 2025

1. 01*

   Search for Double Beta Decay of ${}^{136}$Xe to the $0_1^{+}$ Excited State of ${}^{136}$Ba with PandaX-4T

   PandaX Collaboration: Lingyin Luo · Zihao Bo🇨🇳 · Wei Chen · Xun Chen · Yunhua Chen · Zhaokan Cheng🇨🇳 · Xiangyi Cui🇨🇳 · Yingji Fang🇨🇳 · Deqing Fang · Zhixing Gao🇨🇳 · Lisheng Geng🇨🇳 · Karl Giboni🇨🇳 and 88 other authors

   We perform a search of double beta decay of ${}^{136}$Xe to the excited state, $0_1^{+}$, of ${}^{136}$Ba (2$\nu \beta \beta$-0${}_1^{+}$), using the dual-phase xenon detector of PandaX-4T with the first 94.9-day commissioning data. The multi-site events are reconstructed up to the MeV energy scale, which helps to improve the background model significantly. The background contribution from the stainless steel platform outside PandaX-4T cryostat is evaluated for the first time. No significant evidence for 2$\nu \beta \beta$-$0_1^{+}$ is observed, resulting in a lower limit on half-life of $7.5\times 10^{22}$ yr at the 90% confidence level. This is the first experimental limit on such a rare decay in a natural xenon-based detector.

   nucl-exJHEP(2025)·6 citations
2. 02*

   Bremsstrahlung photon contributions to parton energy loss at high virtuality ($Q^2$) : a perturbative calculation at $O({\alpha }_s{\alpha }_{em})$

   Amit Kumar🇨🇦 · Gojko Vujanovic🇨🇦

   In this work, real photon production scattering kernels from jet-medium interactions in the QCD medium are perturbatively calculated using the higher-twist (HT) formalism. Focus is given towards real photon production from a highly virtual (and highly energetic) quark, taking into account heavy-quark mass scales [Phys. Rev. C 94, 054902 (2016)], fermion-boson conversion processes [Nucl. Phys. A 793, 128 (2007)], as well as coherence effects [Phys. Rev. C 105, 024908 (2022)]. A generalized factorization procedure, such as that used in e-A deep-inelastic scattering, is employed to derive an improved single-scattering medium-induced photon emission kernels that go beyond the traditional in-medium gluon exchange approximation. Diagrams with real-photon emission from the hard quark are classified based on the final-state particles, and include two types of scattering kernels at $O({\alpha }_{em}{\alpha }_s)$ giving the following final states: (i) real photon and real quark, (ii) real photon and real gluon. The collisional kernels, thus derived, include full phase factors from all non-vanishing diagrams and complete second-order derivative terms in the transverse momentum gradient expansion. Moreover, the calculation includes heavy-quark mass effects, thus exploring heavy-quark energy loss. The in-medium parton distribution functions and the related jet transport coefficients have a hard transverse momentum dependence (of the emitted gluon or photon) present within the phase factor. It is observed that the jet transport coefficients resemble the transverse-momentum-dependent parton distribution functions.

   ↳ hep-phnucl-exnucl-thPRC(2025)·4 citations
3. 03*

   Probing new hadronic forces with heavy exotic atoms

   Hongkai Liu🇺🇸 · Ben Ohayon🇮🇱 · Omer Shtaif🇮🇱 · Yotam Soreq🇮🇱

   We explore the potential of precision spectroscopy of heavy exotic atoms where electrons are substituted by negative hadrons to detect new force carriers with hadronic couplings. The selected transitions are unaffected by nuclear contact terms, thus enabling highly accurate calculations using bound-state QED, provided that the nuclear polarization is under control. Alternatively, we demonstrate that the dipole polarizability, a fundamental property of nuclei, can be extracted from the spectroscopy of exotic atoms in a novel way by combining two transitions while maintaining high sensitivity to new physics. Based on existing data, we extracted world-leading bounds on mediator masses ranging from $0.1$MeV to $10$MeV for two benchmark models and show that forthcoming experiments could enhance the sensitivity to new physics by two orders of magnitude.

   ↳ hep-phhep-exnucl-exphysics.atom-phPRL(2025)·15 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.