Tue·Oct 2, 2018Tuesday·October 2, 2018

1. 01*

   High-resolution (p,t) reaction measurements as spectroscopic tests of {\it ab-initio} theory in the mid $pf$-shell

   K.G. Leach🇺🇸 · J.D. Holt🇨🇦 · P.E. Garrett🇨🇦 · S.R. Stroberg🇨🇦 · G.C. Ball🇨🇦 · P.C. Bender🇨🇦 · V. Bildstein🇨🇦 · A. Diaz Varela🇨🇦 · R. Dunlop🇨🇦 · T. Faestermann🇩🇪 · B. Hadinia · R. Hertenberger🇩🇪 and 9 other authors

   Detailed spectroscopic measurements of excited states in ${}^{50}$Cr and ${}^{62}$Zn were performed using 24~MeV (p,t) transfer reactions on ${}^{52}$Cr and ${}^{64}$Zn, respectively. In total, forty-five states in ${}^{50}$Cr and sixty-seven states in ${}^{62}$Zn were observed up to excitation energies of 5.5~MeV, including several previously unobserved states. These experimental results are compared to {\it ab-initio} shell-model calculations using chiral effective field theory ($\chi$-EFT) with the valence-space in-medium similarity renormalization group (VS-IMSRG) method. This comparison demonstrates good agreement in the level orderings with these new theoretical methods, albeit with a slight over binding in the calculations. This work is part of a continued push to benchmark {\it ab-initio} theoretical techniques to nuclear structure data in $0^{+}\to 0^{+}$ superallowed Fermi $\beta$ decay systems.

   nucl-exnucl-thPRC(2019)·2 citations
2. 02*

   Open charm measurements in NA61/SHINE at CERN SPS

   Pawel Staszel (for the NA61/SHINE Collaboration)🇵🇱

   The measurements of open charm production was proposed as an important tool to investigate the properties of hot and dense matter formed in nucleus-nucleus collisions as well as to provide the means for model independent interpretation of the existing data on $\text{J}/\psi$ suppression. Recently, the experimental setup of the NA61/SHINE experiment was supplemented with a Vertex Detector which was motivated by the importance and the possibility of the first direct measurements of open charm meson production in heavy ion collisions at SPS energies. First test data taken in December 2016 on Pb+Pb collisions at 150$A$ GeV/$c$ allowed to validate the general concept of D${}^0$ meson detection via its D${}^0\to {\pi }^{+}+K^{-}$ decay channel and delivered a first indication of open charm production. The physics motivation of open charm measurements at SPS energies, pilot results on open charm production, and finally, the future plans of open charm measurements in the NA61/SHINE experiment after LS2 are presented.

   nucl-exNPA(2019)·3 citations
3. 03*

   Measurement of the electron-antineutrino correlation in neutron beta decay: aCORN experiment

   F. E. Wietfeldt🇺🇸 · W. A. Byron🇺🇸 · G. Darius🇺🇸 · C. R. DeAngelis🇺🇸 · M. T. Hassan🇺🇸 · M. S. Dewey🇺🇸 · M. P. Mendenhall🇺🇸 · J. S. Nico🇺🇸 · B. Collett🇺🇸 · G. L. Jones🇺🇸 · A. Komives🇺🇸 · E. J. Stephenson🇺🇸

   The aCORN experiment uses a novel asymmetry method to measure the electron-antineutrino correlation (a-coefficient) in free neutron decay that does not require precision proton spectroscopy. aCORN completed two physics runs at the NIST Center for Neutron Research. The first run on the NG-6 beam line in 2013--2014 obtained the result a = 0.1090 +/- 0.0030 (stat) +/- 0.0028 (sys), a total uncertainty of 3.8%. The second run on the new NG-C high flux beam line promises an improvement in precision to <2%.

   nucl-exphysics.ins-det2 citations
4. 04*

   The {\eta}'-carbon potential at low meson momenta

   M. Nanova🇩🇪 · S. Friedrich🇩🇪 · V. Metag🇩🇪 · E. Ya. Paryev🇷🇺 · F. N. Afzal🇩🇪 · D. Bayadilov🇩🇪 · B. Bantes🇩🇪 · R. Beck🇩🇪 · M. Becker🇩🇪 · S. Böse🇩🇪 · K.-T. Brinkmann🇩🇪 · V. Crede🇺🇸 and 49 other authors

   The production of ${\eta }^{\prime }$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on ${}^{12}$C and on a liquid hydrogen (LH${}_2$) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The ${\eta }^{\prime }$ mesons have been identified via the ${\eta }^{\prime }\to {\pi }^0{\pi }^0\eta \to 6\gamma$ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF${}_2$ array at polar angles of $2^{\circ }\le {\theta }_p\le 11^{\circ }$. Under these kinematic constraints the ${\eta }^{\prime }$ mesons are produced with relatively low kinetic energy ($\approx$ 150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the ${\eta }^{\prime }$-carbon potential at low meson momenta by comparing with collision model calculations of the ${\eta }^{\prime }$ kinetic energy distribution and excitation function. Fitting the latter data for ${\eta }^{\prime }$ mesons going backwards in the center-of-mass system yields a potential depth of V = $-$(44 $\pm$ 16(stat)$\pm$15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average ${\eta }^{\prime }$ momenta of $\approx$ 1.1 GeV/$c$. Within the experimental uncertainties, there is no indication of a momentum dependence of the ${\eta }^{\prime }$-carbon potential. The LH${}_2$ data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for ${\eta }^{\prime }$ photoproduction off the free proton.

   nucl-exEPJA(2018)·21 citations
5. 05*

   Towards the Minimal Spectrum of Excited Baryons

   J. Landay🇺🇸 · M. Mai🇺🇸 · M. Döring🇺🇸 · H. Haberzettl🇺🇸 · K. Nakayama🇺🇸

   In the light baryon sector resonances can be broad and overlapping and are in most cases not directly visible in the cross section data. Automatized model selection techniques that introduce penalties for resonances can be used to determine the minimally needed set of resonances to describe the data. Several possible penalization schemes are compared. As an application we perform a blindfold identification of hyperon resonances in the $\bar{K}N\to K\Xi$ reaction based on the Least Absolute Shrinkage and Selection Operator (LASSO) in combination with the Bayesian Information Criterion (BIC). We find ten resonances --- out of the 21 above-threshold hyperon resonances with spin $J\le 7/2$ listed by the Particle Data Group. In traditional analyses, it is practically impossible to test the relevance of all resonances and their combinations that may potentially contribute to the reaction. By contrast, the present method proves capable of determining the relevant resonances among a large pool of candidates.

   ↳ nucl-thnucl-exPRD(2019)·23 citations
6. 06*

   Thermal vorticity and spin polarization in heavy-ion collisions

   De-Xian Wei🇨🇳 · Wei-Tian Deng🇨🇳 · Xu-Guang Huang🇨🇳

   The hot and dense matter generated in heavy-ion collisions contains intricate vortical structure in which the local fluid vorticity can be very large. Such vorticity can polarize the spin of the produced particles. We study the event-by-event generation of the so-called thermal vorticity in Au + Au collisions at energy region $\sqrt{s}=7.7-200$ GeV and calculate its time evolution, spatial distribution, etc., in a multiphase transport (AMPT) model. We then compute the spin polarization of the $\Lambda$ and $\bar{\Lambda }$ hyperons as a function of $\sqrt{s}$, transverse momentum $p_T$, rapidity, and azimuthal angle. Furthermore, we study the harmonic flow of the spin, in a manner analogous to the harmonic flow of the particle number. The measurement of the spin harmonic flow may provide a way to probe the vortical structure in heavy-ion collisions. We also discuss the spin polarization of ${\Xi }^0$ and ${\Omega }^{-}$ hyperons which may provide further information about the spin polarization mechanism of hadrons.

   ↳ nucl-thhep-phnucl-exPRC(2019)·181 citations
7. 07*

   ABALONE Photosensors for the IceCube Experiment

   Daniel Ferenc🇺🇸 · Andrew Chang🇺🇸 · Cameron Saylor🇺🇸 · Sebastian Böser🇩🇪 · Alfredo Davide Ferella🇸🇪 · Lior Arazi🇮🇱 · John R. Smith🇺🇸 · Marija Šegedin Ferenc🇺🇸

   The ABALONE Photosensor Technology (U.S. Pat. 9064678) is a modern, scalable technology specifically invented for cost effective mass production, robustness, and high performance. We present the performance of advanced fused silica ABALONE Photosensors, developed specifically for the potential extension of the Ice Cube neutrino experiment, and stress tested for 120 days. The resulting performance makes a significant difference: intrinsic gain in the high 100 million range, total afterpulsing rate of only 0.005 ions per photoelectron, subnanosecond timing resolution, single photon sensitivity, and unique radiopurity and UV sensitivity, thanks to the fused silica components, at no additional cost to the assembly process.

   ↳ physics.ins-detastro-ph.HEhep-exnucl-exNucl.Instrum.Meth.A(2020)·9 citations
8. 08*

   First extraction of transversity from data on lepton-hadron scattering and hadronic collisions

   Marco Radici🇮🇹

   We present the first extraction of the transversity distribution based on the global analysis of pion-pair production in deep-inelastic scattering and in proton-proton collisions with one transversely polarized proton. The extraction relies on the knowledge of di-hadron fragmentation functions, which are taken from the analysis of electron-positron annihilation data. For the first time, the chiral-odd transversity is extracted from a global analysis similar to what is usually done for the chiral-even spin-averaged and helicity distributions. The knowledge of transversity is important among other things for detecting possible signals of new physics in high-precision low-energy experiments.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2019)·2 citations
9. 09*

   Constraining New Muonic Interactions Meditated by Axion-Like-Particles

   H.Yan🇨🇳 · G.A.Sun🇨🇳 · S.M.Peng🇨🇳 · H.Guo · B.Q.Liu🇨🇳 · M.Peng🇨🇳 · H.Zheng🇨🇳

   ALPs (Axion Like Particle) beyond the standard model are solutions to several important problems of modern physics. One way to detect these particles is to detect the new interactions they meditate. Many experiments have been performed to search for these new interactions in ranges from $\sim \mu$m to astrophysical range. At present, nearly all known experiments searching for the ALP-meditated long range new interactions use sources or probes containing protons, neutrons and electrons. Constraints for other fermions such as muons are scarce, though muons might be the most suspicious particles which could take part in new interactions, considering their involvement of several well known puzzles of modern physics. In this work, we discuss the possibility of explaining the anomalous magnetic moment of muons by the long range muonic new interactions mediated by ALPs. We also give a constraint for the scalar-pseudo-scalar(SP) type interaction meditated by muonic ALPs. We propose to further search the muonic SP type interaction by muon spin rotation experiments.

   ↳ hep-phnucl-exnucl-th0 citations
10. 10*

    Automated Discovery of Jet Substructure Analyses

    Yue Shi Lai🇺🇸

    The study of the substructure of collimated particles from quarks and gluons, or jets, has the promise to reveal the details how color charges interact with the QCD plasma medium created in colliders such as RHIC and the LHC. Traditional jet substructure observables have been constructed using expert knowledge, and are largely transplanted, unmodified, from the high-energy physics, where the goal is primarily the study of boosted hadronic decays. A novel neural network architecture is described that is capable of examining theoretical models, and constructs, on its own, an analysis procedure that is sensitive to the internal model features. This architecture, in combination with symbolic regression, further allows the extraction of closed-form algebraic expressions from the learned result -- enabling the automatically constructed jet substructure analysis to be subsequently understood and reproduced by humans. This system is then tasked to construct an analysis that infers the plasma temperature from observing jets, which is demonstrated using both JEWEL and the Linearized Boltzmann Transport model, and at the presence of a realistic remnant of the plasma, or underlying event, that the measurement has to overcome. In a demonstration how algorithms can produce original research in direct competition to human experts, the resulting jet substructure variables and analyses are capable of determining the initial temperature of the plasma medium from analyzing 1200--2500 jets, a performance not seen in existing, manually designed analyses. Comparison of an incidentally discovered observable with the existing literature further indicates that the system described is capable of examining the model phase spaces to a detail at least comparable to the current field of human experts.

    ↳ nucl-thnucl-ex11 citations
11. 11*

    Neutron Lifetime Discrepancy as a Sign of a Dark Sector?

    Bartosz Fornal🇺🇸 · Benjamin Grinstein🇺🇸

    We summarize our recent proposal of explaining the discrepancy between the bottle and beam measurements of the neutron lifetime through the existence of a dark sector, which the neutron can decay to with a branching fraction 1%. We show that viable particle physics models for such neutron dark decays can be constructed and we briefly comment on recent developments in this area.

    ↳ hep-phnucl-exnucl-th5 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.