Fri·May 3, 2024Friday·May 3, 2024

1. 01*

   Femtoscopy with Lévy sources at NA61/SHINE

   Barnabas Porfy (for the NA61/SHINE Collaboration)🇭🇺

   In the recent decades of high-energy physics research, it was demonstrated that strongly interacting quark-gluon plasma (sQGP) is created in ultra-relativistic nucleus-nucleus collisions. Investigation and understanding of the properties of the hadronic matter are among the most important goals of the NA61/SHINE collaboration at CERN SPS. Mapping of the phase diagram is achieved by varying the collision energy (5 GeV $\sqrt{s_{NN}}<17$ GeV) and by changing the collision system ($p$+$p$, $p$+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb). Femtoscopic correlations reveal the space-time structure of the hadron emitting source. In this article, we report on the measurement of femtoscopic correlations in small to intermediate systems. Comparing the measurements to calculations based on symmetric Lévy sources, we discuss the results on Lévy source parameters as a function of average pair transverse mass. One of the physical parameters is of particular importance, the Lévy exponent $\alpha$, which describes the shape of the source and may be related to the critical exponent $\eta$ in the proximity of the critical point. Therefore, measuring it may shed light on the location of the critical endpoint of the QCD phase diagram.

   nucl-exhep-exNuovo Cim.C(2025)·0 citations
2. 02*

   Detailed study of the decay of ${}^{21}$Mg

   E. A. M. Jensen🇩🇰 · S. T. Nielsen · A. Andreyev · M. J. G. Borge🇪🇸 · J. Cederkäll🇸🇪 · L. M. Fraile🇪🇸 · H. O. U. Fynbo🇩🇰 · L. J. Harkness-Brennan🇬🇧 · B. Jonson · D. S. Judson🇬🇧 · O. S. Kirsebom · R. Lică🇷🇴 and 8 other authors

   Beta-delayed proton and gamma emission in the decay of ${}^{21}$Mg has been measured at ISOLDE, CERN with the ISOLDE Decay Station (IDS) set-up. The existing decay scheme is updated, in particular what concerns proton transitions to excited states in ${}^{20}$Ne. Signatures of interference in several parts of the spectrum are used to settle spin and parity assignments to highly excited states in ${}^{21}$Na. The previously reported $\beta$p$\alpha$ branch is confirmed. A half-life of 120.5(4) ms is extracted for ${}^{21}$Mg. The revised decay scheme is employed to test mirror symmetry in the decay and to extract the beta strength distribution of ${}^{21}$Mg that is compared with theory.

   nucl-exEPJA(2024)·2 citations
3. 03*

   Proposal for PAC 52: Measurement of ${\alpha }_{-}$ for $\Lambda \to p{\pi }^{-}$

   Peter Hurck🇬🇧 · Derek I. Glazier🇬🇧 · David G. Ireland🇬🇧 · Ken Livingston🇬🇧 · Farah Afzal🇩🇪 · Annika Thiel🇩🇪 · Yannick Wunderlich🇩🇪 · Volker Crede🇺🇸 · Mark M. Dalton🇺🇸

   We propose to measure the weak decay constant ${\alpha }_{-}$ for the decay $\Lambda \to p{\pi }^{-}$ using a both circularly and linearly polarized photon beam with the GlueX spectrometer in Hall D. The measurement will take advantage of the fact that a measurement with both linear and circular photon beam polarization results in an over-constrained set of amplitudes which can be fitted to data and used to extract ${\alpha }_{-}$ which will be left as a free parameter in the fit. We expect to determine ${\alpha }_{-}$ with statistical uncertainties comparable to existing measurements and independent systematic uncertainties. This measurement can be performed alongside GlueX-II running and requires no new hardware or new beam time. The measurement requires that a sufficient fraction of the electron beam polarization be longitudinal in the Hall D tagger.

   nucl-exhep-ex4 citations
4. 04*

   Data-driven analysis of the beauty hadron production in p+p collisions at the LHC with Bayesian unfolding

   Xiaozhi Bai🇨🇳 · Guangsheng Li🇨🇳 · Yifei Zhang🇨🇳 · Qingyi Situ🇨🇳 · Xiaolong Chen🇨🇳

   Heavy flavour production in proton-proton (pp) collisions provides insights into the fundamental properties of Quantum Chromodynamics (QCD). Beauty hadron production measurements are widely performed through indirect approaches based on their inclusive decay modes. A Bayesian unfolding data-driven analysis of the ALICE and LHCb data was performed in this study, which recovers the full kinematic information of the beauty hadrons via different inclusive decay channels. The corresponding beauty hadron production cross sections obtained after the Bayesian unfolding are found to be consistent within their uncertainties. The weighted average open beauty production cross sections are presented as a function of the transverse momentum and rapidity in pp collisions at $\sqrt{s}$ = 5.02 TeV and $\sqrt{s}$ = 13 TeV, respectively. The $p_T$-integrated open beauty production $\mathrm{d}\sigma /\mathrm{d}y$ and the total $\mathrm{b}\overline{\mathrm{b}}$ cross section ${\sigma }_{\mathrm{b}\overline{\mathrm{b}}}$ are also reported. The precision of these results significantly improves upon worldwide measurements, providing valuable validation and constraints on mechanisms of heavy flavour production in pp collisions at the LHC energies.

   nucl-exJHEP(2024)·5 citations
5. 05*

   Probing the structure of $X(3872)$ in photoproduction

   E. Ya. Paryev🇷🇺

   We study the production of $X(3872)$ mesons in photon-induced nuclear reactions near the threshold within the collision model based on the nuclear spectral function. The model accounts for direct photon-nucleon $X(3872)$ production processes as well as five different scenarios for their internal structure. We calculate the absolute and relative excitation functions for $X(3872)$ production off ${}^{12}$C and ${}^{184}$W target nuclei at near-threshold incident photon energies of 8--16 GeV, the absolute differential cross sections for their production off these target nuclei at laboratory angles of 0${}^{\circ }$--10${}^{\circ }$ and for incident photon energy of 13 GeV as well as the A dependences of the relative (transparency ratios) cross sections for $X(3872)$ production from $\gamma A$ collisions at photon energies around 13 GeV within the adopted scenarios for the $X(3872)$ meson internal structure. We show that the absolute and relative observables considered reveal distinct sensitivity to these scenarios. Therefore, the measurement of such observables in a dedicated experiment at the CEBAF facility in the near-threshold energy range will allow us to get valuable information on the $X(3872)$ inner structure.

   ↳ hep-phhep-exnucl-exNPA(2024)·5 citations
6. 06*

   Novel method for in-situ drift velocity measurement in large volume TPCs: the Geometry Reference Chamber of the NA61/SHINE experiment at CERN

   Andras Laszlo🇭🇺 · Adam Gera🇭🇺 · Gergo Hamar🇭🇺 · Botond Palfi🇭🇺 · Piotr Podlaski🇵🇱 · Brant Rumberger🇺🇸 · Dezso Varga🇭🇺

   This paper presents a novel method for low maintenance, low ambiguity in-situ drift velocity monitoring in large volume Time Projection Chambers (TPCs). The method was developed and deployed for the 40m^3 TPC tracker system of the NA61/SHINE experiment at CERN, which has a one meter of drift length. The method relies on a low-cost multi-wire proportional chamber placed next to the TPC to be monitored, downstream with respect to the particle flux. Reconstructed tracks in the TPC are matched to hits in the monitoring chamber, called the Geometry Reference Chamber (GRC). Relative differences in positions of hits in the GRC are used to estimate the drift velocity, removing the need for an accurate alignment of the TPC to the GRC. An important design requirement on the GRC was minimal added complexity to the existing system, in particular, compatibility with Front-End Electronics cards already used to read out the TPCs. Moreover, the GRC system was designed to operate both in large and small particle fluxes. The system is capable of monitoring the evolution of the drift velocity inside the TPC down to a one permil precision, with a few minutes of data collection.

   ↳ physics.ins-dethep-exnucl-exJINST(2024)·0 citations
7. 07*

   The odd-even differences in stability peninsula for $106⩽Z⩽112$ region with the deformed relativistic Hartree-Bogoliubov theory in continuum

   Xiao-Tao He🇨🇳 · Jia-Wei Wu · Kai-Yuan Zhang🇨🇳 · Cai-Wan Shen

   The predictive power of the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with density functional PC-PK1 is demonstrated for superheavy region ($101⩽Z⩽120$) by comparing with available experimental and evaluated data in the AME2020. The DRHBc theory predicts 93 bound nuclei beyond the drip line $N=258$ in the region of $106⩽Z⩽112$, which form a stability peninsula. The odd-even differences between odd-$N$ and even-$N$ nuclei are remarkable in the stability peninsula; the number of bound odd-$N$ nuclei is less than that of bound even-$N$ nuclei, and the one-neutron separation energy of an odd-$N$ nucleus is smaller than those of its neighboring even-$N$ nuclei due to the blocking effect. The deformation effect is indispensable for the reentrant stability beyond the drip line by significantly affecting the structure of single-particle levels around the Fermi energy. The interplay between deformation and pairing effects affects the position where the odd-$N$ nucleus becomes bound in the stability peninsula. By examining the deformation effect at different orders, it is found that quadrupole deformation makes leading contribution to the appearance of stability peninsula and the effects of hexadecapole and hexacontatetrapole deformations are nonnegligible.

   ↳ nucl-thnucl-exPRC(2024)·20 citations
8. 08*

   Development of the strip LGAD detector with double-end readout for future colliders

   Weiyi Sun🇨🇳 · Mengzhao Li🇨🇳 · Tianyuan Zhang🇨🇳 · Mei Zhao🇨🇳 · Yunyun Fan🇨🇳 · Shuqi Li🇨🇳 · Yuan Feng🇨🇳 · Xinhui Huang🇨🇳 · Xuan Yang🇨🇳 · Wei Wang🇨🇳 · Zhijun Liang🇨🇳 · Yuekun Heng🇨🇳

   The Low-Gain Avalanche Diode (LGAD) is a new silicon detector and holds wide application prospects in particle physics experiments due to its excellent timing resolution. The LGAD with a pixel size of 1.3 mm $\times$ 1.3 mm was used to construct a High Granularity Timing Detector (HGTD) in ATLAS experiments to solve the pile-up problem. Meanwhile, the Circular Electron Positron Collider (CEPC) also proposes detectors using the LGAD. However, pixel LGAD exhibits higher readout electronics density and cost, which somewhat limits the application of LGADs. To decrease the readout electronics density, the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences has designed strip LGADs with larger areas. These strip LGADs are all 19 mm in length but with different widths of 1.0 mm, 0.5 mm, and 0.3 mm. This article provides a detailed introduction to the design parameters of these strip LGADs and tests their electrical characteristics, including leakage current, break-down voltage, depletion capacitance, etc. The timing resolution and signal-to-noise ratio of the three strip LGAD sensors were investigated using a beta source test system. The position resolution parallel to the strip direction was tested and analyzed for the first time using a pico-second laser test system. Tests have demonstrated that the timing resolution of strip LGADs can reach about 37.5 ps, and position resolution parallel to the strip direction is better than 1 mm.

   ↳ physics.ins-detnucl-exNucl.Sci.Tech.(2026)·0 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.