Mon·May 20, 2024Monday·May 20, 2024

1. 01*

   Measurement of Ionization Produced by 254 eVnr Nuclear Recoils in Germanium

   A.R.L. Kavner🇺🇸 · I. Jovanovic🇺🇸

   Ionization produced by low-energy nuclear recoils is among the primary direct signatures of dark matter interactions. Despite the urgency of dark matter detection and the recent measurements of coherent elastic neutrino-nucleus scattering, detector response to nuclear recoils is not well characterized in the keVnr and sub-keVnr regime across a variety of materials. We have re-performed a measurement of the ionization produced by monoenergetic 254 eVnr nuclear recoils in Ge with improved digital electronics and additional systematic studies. Our results indicate an ionization yield of 64 +/- 8 eVee corresponding to a quenching factor of 25 +/- 3%, greater than the 14% predicted by the Lindhard model. This ionization enhancement could greatly improve the sensitivity of high-purity Ge detectors in dark matter detection and measurement of neutrinos via coherent scattering.

   nucl-exphysics.ins-detPRD(2024)·12 citations
2. 02*

   Searching for Beyond the Standard Model physics using the improved description of ${}^{100}$Mo $2\nu \beta \beta$ decay spectral shape with CUPID-Mo

   C. Augier🇫🇷 · A. S. Barabash🇷🇺 · F. Bellini🇮🇹 · G. Benato🇮🇹 · M. Beretta🇺🇸 · L. Bergé🇫🇷 · J. Billard🇫🇷 · Yu. A. Borovlev🇷🇺 · L. Cardani🇮🇹 · N. Casali🇮🇹 · A. Cazes🇫🇷 · E. Celi🇮🇹 and 71 other authors

   The current experiments searching for neutrinoless double-$\beta$ ($0\nu \beta \beta$) decay also collect large statistics of Standard Model allowed two-neutrino double-$\beta$ ($2\nu \beta \beta$) decay events. These can be used to search for Beyond Standard Model (BSM) physics via $2\nu \beta \beta$ decay spectral distortions. ${}^{100}$Mo has a natural advantage due to its relatively short half-life, allowing higher $2\nu \beta \beta$ decay statistics at equal exposures compared to the other isotopes. We demonstrate the potential of the dual read-out bolometric technique exploiting a ${}^{100}$Mo exposure of 1.47 kg $\times$ y, acquired in the CUPID-Mo experiment at the Modane underground laboratory (France). We set limits on $0\nu \beta \beta$ decays with the emission of one or more Majorons, on $2\nu \beta \beta$ decay with Lorentz violation, and $2\nu \beta \beta$ decay with a sterile neutrino emission. In this analysis, we investigate the systematic uncertainty induced by modeling the $2\nu \beta \beta$ decay spectral shape parameterized through an improved model, an effect never considered before. This work motivates searches for BSM processes in the upcoming CUPID experiment, which will collect the largest amount of $2\nu \beta \beta$ decay events among the next-generation experiments.

   nucl-exEPJC(2024)·12 citations
3. 03*

   Overview of high-density QCD studies with the CMS experiment at the LHC

   CMS Collaboration

   We review key measurements performed by CMS in the context of its heavy ion physics program, using event samples collected in 2010-2018 with several collision systems and energies. These studies provide detailed macroscopic and microscopic probes of the quark-gluon plasma (QGP) created at the LHC energies, a medium characterized by the highest temperature and smallest baryon-chemical potential ever reached in the laboratory. Numerous observables related to high-density quantum chromodynamics (QCD) were studied, leading to some of the most impactful and qualitatively novel results in the 40-year history of the field. Using a dedicated high-multiplicity trigger in the first pp run, CMS discovered that small collision systems can exhibit signs of collectivity, a generic phenomenon with significant implications and presently understood to affect essentially all soft physics processes. This observation opened new paths to understand how fluidity and plasma properties emerge in QCD matter as a function of system size. Measurements of jet quenching have reached a completely new level of detail by directly assessing, for the first time, the medium modification of parton showers, as opposed to simply observing leading hadrons or di-hadrons. The first fully reconstructed beauty hadron and heavy-flavor jet nuclear modifications were also measured. The large size of the event samples, the precision of the measurements, and the extension of the probed kinematical phase space, allowed many other hard probes of the QGP medium to be explored in detail, leading to multiple groundbreaking findings. In particular, the seminal measurements of bottomonium suppression patterns answer fundamental questions that have been actively pursued, both theoretically and experimentally, by the community since the mid-1980s. We conclude by outlining the opportunities offered by the continuation of this physics program at the LHC.

   nucl-exhep-exPhys.Rept.(2025)·124 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.