Wed·Jul 28, 2021Wednesday·July 28, 2021

1. 01*

   Measurement of the groomed jet radius and momentum splitting fraction in pp and Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   This article presents groomed jet substructure measurements in pp and Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE detector. The Soft Drop grooming algorithm provides access to the hard parton splittings inside a jet by removing soft wide-angle radiation. We report the groomed jet momentum splitting fraction, $z_{\mathrm{g}}$, and the (scaled) groomed jet radius, ${\theta }_{\mathrm{g}}$. Charged-particle jets are reconstructed at midrapidity using the anti-kT algorithm with resolution parameters $R=0.2$ and $R=0.4$. In heavy-ion collisions, the large underlying event poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed parton splittings to be misidentified. By using strong grooming conditions to reduce this background, we report these observables fully corrected for detector effects and background fluctuations for the first time. A narrowing of the ${\theta }_{\mathrm{g}}$ distribution in Pb$-$Pb collisions compared to pp collisions is seen, which provides direct evidence of the modification of the angular structure of jets in the quark$-$gluon plasma. No significant modification of the $z_{\mathrm{g}}$ distribution in Pb$-$Pb collisions compared to pp collisions is observed. These results are compared with a variety of theoretical models of jet quenching, and provide constraints on jet energy-loss mechanisms and coherence effects in the quark$-$gluon plasma.

   nucl-exhep-exPRL(2022)·136 citations
2. 02*

   3D cosmic-ray muon tomography using portable muography detector

   Kullapha Chaiwongkhot (1 and 2)🇯🇵 · Tadahiro Kin (1)🇯🇵 · Yuta Nagata (1)🇯🇵 · Tomohiro Komori (1)🇯🇵 · Naoya Okamoto (1)🇯🇵 · Hamid Basiri (1) ((1) 1 Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Fukuoka, Japan (2) Department of Physics, Mahidol University, Bangkok, Thailand)🇯🇵

   A feasibility demonstration of three-dimensional (3D) muon tomography was performed for infrastructure equivalent targets using the proposed portable muography detector. For the target, we used two sets of lead blocks placed at different heights. The detector consists of two muon position-sensitive detectors, made of plastic scintillating fibers (PSFs) and multi-pixel photon counters (MPPCs) with an angular resolution of 8 msr. The maximum likelihood-expectation maximization (ML-EM) method was used for the 3D imaging reconstruction of the muography simulation and measurement. For both simulation and experiment, the reconstructed positions of the blocks produce consistent results with prior knowledge of the blocks' arrangement. This result demonstrates the potential of the 3D tomographic imaging of infrastructure by using eleven detection positions for portable muography detectors to image infrastructure scale targets.

   ↳ physics.ins-dethep-exnucl-exJINST(2022)·2 citations
3. 03*

   Weisskopf units for neutron-proton pair transfers

   J. A. Lay🇪🇸 · Y. Ayyad🇪🇸 · A. O. Macchiavelli🇺🇸

   We introduce the concept of neutron-proton two-particle units ($np$-Weisskopf units) to be used in the analysis of the (${}^3$He,$p)$ and $(p{,}^3$He) \added{reactions on nuclei} along the N=Z line. These are presented for the conditions relevant to the $(n,j,\ell$) orbits expected from ${}^{16}$O to ${}^{100}$Sn. As is the case of the Weisskopf units for electromagnetic transitions, the $np$-WU's will provide a simple, yet robust, measure of isoscalar and isovector $np$ pairing collective effects.

   ↳ nucl-thnucl-exPLB(2022)·4 citations
4. 04*

   A new empirical formula for {\alpha}-decay half-life and decay chains of Z=120 isotopes

   G. Saxena🇮🇳 · A. Jain🇮🇳 · P. K. Sharma🇮🇳

   Experimental $\alpha$-decay half-life, spin, and parity of 398 nuclei in the range 50$\le$Z$\le$118 are utilized to propose a new formula (QF) with only 4 coefficients as well as to modify the Tagepera-Nurmia formula with just 3 coefficients (MTNF) by employing nonlinear regressions. These formulas, based on reduced mass ($\mu$) and angular momentum taken away by the $\alpha$-particle, are ascertained very effective for both favoured and unfavoured $\alpha$-decay in addition to their excellent match with all (Z, N) combinations of experimental $\alpha$-decay half-lives. After comparing with similar other empirical formulas of $\alpha$-decay half-life, QF and MTNF formulas are purported with accuracy, minimum uncertainty and deviation, dependency on least number of fitted coefficients together with less sensitivity to the uncertainties of $Q$-values. The QF formula is applied to predict $\alpha$-decay half-lives for 724 favoured and 635 unfavoured transitions having experimentally known $Q$-values. Moreover, these available $Q$-values are also employed to test various theoretical approaches viz. RMF, FRDM, WS4, RCHB, etc. along with machine learning method XGBoost for determining theoretical $Q$-values, incisively. Thereafter, using $Q$-values from the most precise theoretical treatment mentioned above along with the proposed formulas, probable $\alpha$-decay chains for Z$=$120 isotopes are identified.

   ↳ nucl-thnucl-exPhys.Scripta(2021)·31 citations
5. 05*

   Measurement of Bell-type inequalities and quantum entanglement from $\Lambda$-hyperon spin correlations at high energy colliders

   Wenjie Gong🇺🇸 · Ganesh Parida🇺🇸 · Zhoudunming Tu🇺🇸 · Raju Venugopalan🇺🇸

   Spin correlations of $\Lambda$-hyperons embedded in the QCD strings formed in high energy collider experiments provide unique insight into their locality and entanglement features. We show from general considerations that while the Clauser-Horne-Shimony-Holt inequality is less stringent for such states, they provide a benchmark for quantum-to-classical transitions induced by varying i) the associated hadron multiplicity, ii) the spin of nucleons, iii) the separation in rapidity between pairs, and iv) the kinematic regimes accessed. These studies also enable the extraction of quantitative measures of quantum entanglement. We first explore such questions within a simple model of a QCD string composed of singlets of two partial distinguishable fermion flavors and compare analytical results to those obtained on quantum hardware. We further discuss a class of spin Hamiltonians that model the dynamics of $\Lambda$ spin correlations. Prospects for extracting quantum features of QCD strings from hyperon measurements at current and future colliders are outlined.

   ↳ hep-phnucl-exnucl-thquant-phPRD(2022)·91 citations
6. 06*

   Reaction Losses of Charged Particles in CsI(Tl) crystals

   S. Sweany🇺🇸 · W. G. Lynch🇺🇸 · K. Brown🇺🇸 · A. Anthony🇺🇸 · Z. Chajecki🇺🇸 · D. Dell'Aquila🇮🇹 · P. Morfouace🇫🇷 · F. C. E. Teh🇺🇸 · C. Y. Tsang🇺🇸 · M. B. Tsang🇺🇸 · R. S. Wang🇺🇸 · K. Zhu🇺🇸

   To efficiently detect energetic light charged particles, it is common to use arrays of energy-loss telescopes involving two or more layers of detection media. As the energy of the particles increases, thicker layers are usually needed. However, carrying out measurements with thick-telescopes may require corrections for the losses due to nuclear reactions induced by the incident particles on nuclei within the detector and for the scattering of incident particles out of the detector, without depositing their full energy in the active material. In this paper, we develop a method for measuring such corrections and determine the reaction and out-scattering losses for data measured with the silicon-CsI(Tl) telescopes of the newly developed HiRA10 array. The extracted efficiencies are in good agreement with model predictions using the GEANT4 reaction loss algorithm for Z=1 and Z=2 isotopes. After correcting for the HiRA10 geometry, a general function that describes the efficiencies from the reaction loss in CsI(Tl) crystals as a function of range is obtained.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2021)·9 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.