Mon·Dec 9, 2024Monday·December 9, 2024

1. 01*

   Study of the deuterons emission time in pp collisions at the LHC via kaon-deuteron correlations

   Oton Vázquez Doce🇮🇹 · Dimitar Mihaylov🇩🇪 · Laura Fabbietti🇩🇪

   The femtoscopy correlation between positively charged kaons and deuterons measured in pp collisions at $\sqrt{s}=$ 13 TeV at the LHC with the ALICE experiment is employed to determine the upper limit for the time delay of the deuteron emission with respect to all other hadrons. Two scenarios are considered: the first assumes that deuterons form following the decays of short-lived strong resonances, while the second assumes that deuteron production occurs simultaneously with all other primary hadrons. For both scenarios, an additional delay time can be introduced using the CECA source model and its upper limit can be extracted by fitting the femtoscopy correlation. Two models are considered for the strong K${}^{+}$d final state interaction. For the scenario where deuterons production is affected by baryonic resonances the upper limit of the time delay is 2.25 fm/c, while for the primary production scenario the upper limit is 4.75 fm/c. These results support the hypothesis of an early formation of the deuteron as an extended, weakly bound composite object in ultra-relativistic proton-proton collisions at the LHC.

   nucl-exhep-phEPJA(2025)·9 citations
2. 02*

   Photon vortex generation from nonlinear Compton scattering in Feynman approach

   Tomoyuki Maruyama🇯🇵 · Takehito Hayakawa🇯🇵 · Ryoichi Hajima🇯🇵 · Toshitaka Kajino🇨🇳 · Myung-Ki Cheoun🇰🇷

   In the present study, we show calculation of nonlinear Compton scattering with circularly polarized photons in a cylindrical coordinate using Feynman diagram to calculate photon vortex generation in intermediate states considering conservation of angular momentum. We take two different vortex wave functions based on Bessel function for the emitted photon and the electron after emission of the photon, which are the eigenstate of z component of the total angular momentum (zTAM) when a particle propagates along z axis. The result shows that when an electron absorbs N photons a photon vortex with a zTAM = N is predominantly radiated, but there are still very small contributions of photons with a zTAM = (N-1) and (N +1) due to the spin flip of the initial electron. This means even when an electron absorbs only a single photon, the electron may emit a photon vortex of a zTAM of 2 h-bar. However, the numerical calculations show that the contribution of the spin flip is four orders of magnitude smaller than that of the dominant radiation. We also discuss the circular polarization for the generated photon vortices.

   ↳ hep-phnucl-exnucl-thphysics.opticsPRD(2025)·1 citation
3. 03*

   Simulation Tool Development and Sensitivity Analysis of 160Gd Double Beta Decay Search by the PIKACHU Project

   Takumi Omori🇯🇵 · Takashi Iida🇯🇵 · Nobuo Hinohara🇯🇵 · Kotaro Takahashi🇯🇵 · Ken-Ichi Fushimi🇯🇵 · Azusa Gando🇯🇵 · Keishi Hosokawa🇯🇵 · Shotaro Ishidate🇯🇵 · Motonao Ishigami🇯🇵 · Kei Kamada🇯🇵 · Keita Mizukoshi🇯🇵 · Yasuhiro Shoji🇯🇵 · Hisanori Suzuki🇯🇵 · Masao Yoshino🇯🇵

   Neutrinoless double beta decay (0v2b) has been investigated as a physical process that can provide evidence for the Majorana nature of neutrinos. The theoretical predictions of the 0v2b rate are subject to significant uncertainty, primarily due to nuclear matrix elements (NME). To reduce this uncertainty, experimental measurements of the half-lives of two-neutrino double beta decay (2v2b) in various nuclei are essential as a benchmark for NME calculations. The PIKACHU (Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences) project searches for the previously unobserved 2v2b decay of 160Gd, employing Ce-doped Gd3Ga3Al2O12 (GAGG) single crystals. In the Phase 1 experiment, we aim to improve the current lower limit on the 2v2b half-life of 160Gd by a prior study using a Ce-doped Gd2SiO5 (GSO) crystal. Ultimately, in Phase 2, the project seeks to achieve a sensitivity surpassing the theoretical prediction of 7.4 x 10^20 years, enabling the potential discovery of the 160Gd 2v2b decay. In this paper, we describe the development of background models based on GEANT4 simulations. The modeled backgrounds are contributions from uranium and thorium decay chains, 40K present in GAGG, and 40K gamma-rays from outside of GAGG. Additionally, we developed models for both 2v2b and 0v2b decay by implementing the theoretical kinematics of two-electron emission in double beta decay in the GEANT4 simulation. As a result, our background models successfully reproduced the measured background spectrum through fitting. By generating pseudo background spectra expected in Phase 1 and analyzing them with the combined background and 2v2b models, we evaluated the 2v2b sensitivity of Phase 1 to be 2.78 x 10^19 years (90% C.L.). This paper presents the development of these simulation models and the expected sensitivities for both Phase 1 and Phase 2 based on the pseudo data analyses.

   ↳ hep-exnucl-exNucl.Instrum.Meth.A(2026)·4 citations
4. 04*

   Excited cluster states: A new source for proton number fluctuations in the high baryon density regime

   Boris Tomasik🇸🇰 · Marcus Bleicher🇩🇪

   We calculate the contribution of the decay products of excited nuclear cluster states to the event-by-event fluctuations of protons in the energy range from $\sqrt{s_{NN}}=2-5$~GeV within the statistical model. We find that the inclusion of the excited nuclear clusters yields corrections to all cumulant ratios, ranging from 1\% for ratio of second to first-order cumulant to 100\% for the sixth to second order cumulant towards the lowest inspected energy. As expected the contribution of excited cluster states is most important at low energies $\sqrt{s_{NN}}<3.5$~GeV and becomes negligible at higher collision energies. Especially in light of the expected ultra-high precision data from CBM at FAIR, this new contribution is important to allow for a quantitative comparison with (potentially later available) lattice QCD or effective model results.

   ↳ nucl-thhep-phnucl-exPLB(2025)·0 citations
5. 05*

   Performance of the prototype beam drift chamber for LAMPS at RAON with proton and Carbon-12 beams

   H. Kim · Y. Bae · C. Heo🇨🇳 · J. Seo🇰🇷 · J. Hwang🇰🇷 · D. H. Moon🇰🇷 · D. S. Ahn🇯🇵 · J. K. Ahn🇰🇷 · J. Bae🇺🇸 · J. Bok🇺🇸 · Y. Cheon · S. W. Choi🇰🇷 and 36 other authors

   Beam Drift Chamber (BDC) is designed to reconstruct the trajectories of incident rare isotope beams provided by RAON (Rare isotope Accelerator complex for ON-line experiments) into the experimental target of LAMPS (Large Acceptance Multi-Purpose Spectrometer). To conduct the performance test of the BDC, the prototype BDC (pBDC) is manufactured and evaluated with the high energy ion beams from HIMAC (Heavy Ion Medical Accelerator in Chiba) facility in Japan. Two kinds of ion beams, 100 MeV proton, and 200 MeV/u ${}^{12}$C, have been utilized for this evaluation, and the track reconstruction efficiency and position resolution have been measured as the function of applied high voltage. This paper introduces the construction details and presents the track reconstruction efficiency and position resolution of pBDC.

   ↳ physics.ins-detnucl-exphysics.acc-phJINST(2024)·1 citation

* 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.