Fri·Sep 6, 2019Friday·September 6, 2019

1. 01*

   Spin polarizabilities of the proton by measurement of Compton double-polarization observables

   D. Paudyal🇨🇦 · P.P. Martel🇩🇪 · G.M. Huber🇨🇦 · D. Hornidge🇨🇦 · S. Abt🇨🇭 · P. Achenbach🇩🇪 · P. Adlarson🇸🇪 · F. Afzal🇩🇪 · Z. Ahmed🇨🇦 · C.S. Akondi🇺🇸 · J.R.M. Annand🇬🇧 · H.J. Arends and 81 other authors

   The Compton double-polarization observable ${\Sigma }_{2z}$ has been measured for the first time in the $\Delta (1232)$ resonance region using a circularly polarized photon beam incident on a longitudinally polarized target at the Mainz Microtron. This paper reports these results, together with the model-dependent extraction of four proton spin polarizabilities from fits to additional asymmetry data using dispersion relation and chiral perturbation theory calculations, with the former resulting in: ${\gamma }_{E1E1}=-3.18\pm 0.52$, ${\gamma }_{M1M1}=2.98\pm 0.43$, ${\gamma }_{E1M2}=-0.44\pm 0.67$ and ${\gamma }_{M1E2}=1.58\pm 0.43$, in units of $10^{-4}{\mathrm{fm}}^4$.

   nucl-exPRC(2020)·18 citations
2. 02*

   Dielectron production at low transverse momentum in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with ALICE

   Sebastian Lehner (on behalf of the ALICE collaboration)🇦🇹

   Dielectrons probe a wide range of phenomena in heavy-ion collisions. These include light- and heavy-flavour meson production, thermal radiation and coherent photo-production. The latter process is distinguished by dielectron production at low transverse-pair momentum ($p_{\text{T,ee}}$). Transverse momentum spectra of dielectrons in central and peripheral Pb-Pb collisions are extracted and compared to the corresponding expectations. In central collisions the data fit the expected spectrum, which is dominated by semi-leptonic decays of correlated heavy-flavour hadrons. In peripheral collisions, the data exhibit an excess at low \ptee with respect to hadronic and thermal sources. The observed excess yield is compatible with calculations for dielectron production from coherent photon-photon interactions.

   nucl-exPoS(2019)·11 citations
3. 03*

   Modeling of GERDA Phase II data

   GERDA collaboration: Matteo Agostini🇩🇪 · Alexander M. Bakalyarov🇷🇺 · Marco Balata🇮🇹 · Igor Barabanov🇷🇺 · Laura Baudis🇨🇭 · Christian Bauer🇩🇪 · Enrico Bellotti🇮🇹 · Sergej Belogurov🇷🇺 · Alessandro Bettini🇮🇹 · Leonid Bezrukov🇷🇺 · Dariusz Borowicz🇷🇺 · Elisabetta Bossio🇩🇪 and 97 other authors

   The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta ($0\nu \beta \beta$) decay of ${}^{76}$Ge. The technological challenge of GERDA is to operate in a "background-free" regime in the region of interest (ROI) after analysis cuts for the full 100kg$\cdot$yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around $Q_{\beta \beta }$ for the $0\nu \beta \beta$ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos ($2\nu \beta \beta$) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for GERDA Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of $16.04_{-0.85}^{+0.78}\cdot 10^{-3}$cts/(kg$\cdot$keV$\cdot$yr) for the enriched BEGe data set and $14.68_{-0.52}^{+0.47}\cdot 10^{-3}$cts/(kg$\cdot$keV$\cdot$yr) for the enriched coaxial data set. These values are similar to the one of Gerda Phase I despite a much larger number of detectors and hence radioactive hardware components.

   nucl-exphysics.ins-detJHEP(2020)·42 citations
4. 04*

   Strangeness production in the new version of the Liège Intra-Nuclear Cascade model

   J. Hirtz🇫🇷 · J.-C. David🇫🇷 · A. Boudard🇫🇷 · J. Cugnon🇧🇪 · S. Leray🇫🇷 · I. Leya🇨🇭 · J.L. Rodríguez-Sánchez🇫🇷 · G. Schnabel🇫🇷

   The capabilities of the new version of the Liège Intra-Nuclear Cascade model (INCL++6) are presented in detail. This new version INCL is able to handle strange particles, such as kaons and the $\Lambda$ particle, and the associated reactions and also allows extending nucleon-nucleon collisions up to about $15-20$ GeV incident energy. Compared to the previous version, new observables can be studied, e.g., kaon, hyperon, and hypernuclei production cross sections (with the use of a suitable de-excitation code) as well as aspects of kaon-induced spallation reactions. The main purpose of this paper is to present the specific ingredients of the new INCL version and its new features, notably the new variance reduction scheme. We also compare for some illustrative strangeness production cases calculated using this version of INCL with experimental data.

   ↳ nucl-thnucl-exPRC(2020)·27 citations
5. 05*

   Improvement for Color Glass Condensate factorization: single hadron production in pA collisions at next-to-leading order

   Hao-Yu Liu🇨🇳 · Yan-Qing Ma🇨🇳 · Kuang-Ta Chao🇨🇳

   High order calculation at semi-hard scale is very important, but a satisfactory calculation framework is still missing. We propose a systematic method to regularize rapidity divergences in the CGC factorization, which makes higher order calculation rigorous and straight forward. By applying this method to single hadron production in pA collision, we find the kinematic constraint effect introduced by hand in previous works comes out automatically, but with different values. The difference is crucial for our next-to-leading order (NLO) result to have a smaller theoretical uncertainty comparing with LO result, which makes high order calculation in CGC factorization to be useful. As a byproduct, the negativity problem found in literature can also be overcome in our framework by a proper choosing of factorization scale.

   ↳ nucl-thhep-exhep-phnucl-exPRD(2019)·27 citations
6. 06*

   Initial and final state temperatures of antiproton emission sources in high energy collisions

   Qi Wang🇨🇳 · Fu-Hu Liu🇨🇳

   The momentum or transverse momentum spectra of antiprotons produced at mid-rapidity in proton-helium ($p$+He), gold-gold (Au+Au), deuton-gold ($d$+Au), and lead-lead (Pb+Pb) collisions over an energy range from a few GeV to a few TeV are analyzed by the Erlang distribution, the inverse power-law (the Hagedorn function), and the blast-wave fit, or the superposition of two-component step function. The excitation functions of parameters such as the mean transverse momentum, initial state temperature, kinetic freeze-out temperature, and transverse flow velocity increase (slightly) from a few GeV to a few TeV and from peripheral to central collisions. At high energy and in central collisions, large collision energy is deposited in the system, which results in high degrees of excitation and expansion.

   ↳ hep-phhep-exnucl-exnucl-thInt.J.Theor.Phys.(2019)·14 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.