Tue·Nov 27, 2018Tuesday·November 27, 2018

1. 01*

   Jet fragmentation transverse momentum measurements from di-hadron correlations in $\sqrt{s}$ = 7 TeV pp and $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV p-Pb collisions

   ALICE Collaboration

   The transverse structure of jets was studied via jet fragmentation transverse momentum ($j_{\mathrm{T}}$) distributions, obtained using two-particle correlations in proton-proton and proton-lead collisions, measured with the ALICE experiment at the LHC. The highest transverse momentum particle in each event is used as the trigger particle and the region $3<p_{\mathrm{Tt}}<15$ GeV/$c$ is explored in this study. The measured distributions show a clear narrow Gaussian component and a wide non-Gaussian one. Based on Pythia simulations, the narrow component can be related to non-perturbative hadronization and the wide component to quantum chromodynamical splitting. The width of the narrow component shows a weak dependence on the transverse momentum of the trigger particle, in agreement with the expectation of universality of the hadronization process. On the other hand, the width of the wide component shows a rising trend suggesting increased branching for higher transverse momentum. The results obtained in pp collisions at $\sqrt{s}$ = 7 TeV and in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are compatible within uncertainties and hence no significant cold nuclear matter effects are observed. The results are compared to previous measurements from CCOR and PHENIX as well as to Pythia 8 and Herwig 7 simulations.

   nucl-exhep-exJHEP(2019)·17 citations
2. 02*

   Lévy-stable two-pion Bose-Einstein correlation functions measured with PHENIX in $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions

   Sándor Lökös (for the PHENIX collaboration)🇭🇺

   Measurement of quantumstatistical correlation functions in high energy nuclear physics is an important tool to investigate the QCD phase diagram. It may be used to search for the critical point, and also to understand underlying processes such as in-medium mass modifications or partially coherent particle production. Furthermore, the measurements of the femtoscopic correlation functions shed light on the space-time structure of particle production. Consequently, the precise measurements and description of the correlation functions are essential. The shape of two-pion Bose-Einstein correlation functions were often assumed to be Gaussian, but the recent precision of the experiments reveals that the statistically correct assumption is the more general Lévy-distribution. In this paper we present the recent results of the measurements of two-pion Lévy-stable Bose-Einstein correlation functions in Au+Au collisions at PHENIX

   nucl-exhep-ex1 citation
3. 03*

   The Nab Experiment: A Precision Measurement of Unpolarized Neutron Beta Decay

   J. Fry🇺🇸 · R. Alarcon🇺🇸 · S. Baessler🇺🇸 · S. Balascuta🇺🇸 · L. Barron-Palos🇲🇽 · T. Bailey🇺🇸 · K. Bass🇺🇸 · N. Birge🇺🇸 · A. Blose🇺🇸 · D. Borissenko🇺🇸 · J. D. Bowman🇺🇸 · L. J. Broussard🇺🇸 and 60 other authors

   Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, $\lambda =g_A/g_V$, through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter $a$ with a precision of $\delta a/a=10^{-3}$ and the Fierz interference term $b$ to $\delta b=3\times 10^{-3}$ in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio $\lambda$ with a precision of $\delta \lambda /\lambda =0.03\%$ that will allow an evaluation of $V_{ud}$ and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.

   nucl-exEPJ Web Conf.(2019)·45 citations
4. 04*

   Status and Prospects of Discrete Symmetries Tests in Positronium Decays with the J-PET Detector

   M. Silarski (for the J-PET Collaboration)🇵🇱

   Positronium is a unique laboratory to study fundamental symmetries in the Standard Model, reflection in space ($\mathcal{P}$), reversal in time ($\mathcal{T}$), charge conjugation ($\mathcal{C}$) and their combinations. The experimental limits on the $\mathcal{C}$, $\mathcal{C}\mathcal{P}$ and $\mathcal{C}\mathcal{P}\mathcal{T}$ symmetries violation in the decays of positronium are still several orders of magnitude higher than the expectations. The newly constructed Jagiellonian Positron Emission Tomograph (J-PET) was optimized for the registration of photons from the electron-positron annihilations. It enables tests of discrete symmetries in decays of positronium atoms via the determination of the expectation values of the discrete-symmetries-odd operators. In this article we present the capabilities of the J-PET detector in improving the current precision of discrete symmetries tests and report on the progress of analysis data from the first data-taking runs.

   nucl-exphysics.ins-detAIP Conf.Proc.(2019)·1 citation
5. 05*

   Competition between direct and sequential two-neutron transfers in the ${}^{18}$O + ${}^{28}$Si collision at 84 MeV

   E. N. Cardozo🇧🇷 · J. Lubian🇧🇷 · R.Linares · F. Cappuzzello🇮🇹 · D. Carbone🇮🇹 · M. Cavallaro🇮🇹 · J.L.Ferreira🇧🇷 · A. Gargano🇮🇹 · B.Paes · G. Santagati🇮🇹

   In this work we study the simultaneous and sequential two-neutron transfer mechanisms to the ${}^{28}$Si nucleus induced by (t,p) and (${}^{18}$O, ${}^{16}$O) reactions. New experimental cross sections for the ${}^{28}$Si(${}^{18}$O,${}^{16}$O)${}^{30}$Si reaction at 84 MeV are also presented. Direct reaction calculations are carried out within the Exact Finite Range Coupled Reaction Channel, for the simultaneous transfer of the two-neutron cluster, and the second order Distorted Wave Born Approximation, for the sequential transfer. Two different models are considered to describe the two-neutron cluster. The spectroscopic information was obtained from shell model calculation with {\it psdmod} interaction for the target overlaps where the 1p${}_{3/2}$, 1p${}_{1/2}$, 1d${}_{3/2}$, 1d${}_{5/2}$ and 2s${}_{1/2}$ orbitals are included as valence sub-space. We show that simultaneous and sequential two-neutron transfer are competing mechanisms for the population of the ground state in ${}^{30}$Si. A systematic analysis of the two-neutron transfer induced by the (${}^{18}O{,}^{16}O$) indicates that static deformation of target nuclei impacts on the two-neutron transfer mechanism.

   nucl-exnucl-thPRC(2018)·46 citations
6. 06*

   Double-beta decay of ${}^{130}$Te to the first $0^{+}$ excited state of ${}^{130}$Xe with CUORE-0

   CUORE Collaboration: C. Alduino · K. Alfonso · D. R. Artusa · F. T. Avignone III · O. Azzolini · T. I. Banks · G. Bari · J.W. Beeman · F. Bellini · A. Bersani · M. Biassoni · C. Brofferio and 108 other authors

   We report on a search for double beta decay of ${}^{130}$Te to the first $0^{+}$ excited state of ${}^{130}$Xe using a 9.8 kg$\cdot$yr exposure of ${}^{130}$Te collected with the CUORE-0 experiment. In this work we exploit different topologies of coincident events to search for both the neutrinoless and two-neutrino double-decay modes. We find no evidence for either mode and place lower bounds on the half-lives: ${\tau }_{0^{+}}^{0\nu }>7.9\cdot 10^{23}$ yr and ${\tau }_{0^{+}}^{2\nu }>2.4\cdot 10^{23}$ yr. Combining our results with those obtained by the CUORICINO experiment, we achieve the most stringent constraints available for these processes: ${\tau }_{0^{+}}^{0\nu }>1.4\cdot 10^{24}$ yr and ${\tau }_{0^{+}}^{2\nu }>2.5\cdot 10^{23}$ yr.

   nucl-exphysics.ins-detEPJC(2019)·22 citations
7. 07*

   Cross Sections for A(e,e')X Reactions

   U. Mosel🇩🇪 · K. Gallmeister🇩🇪

   Recent JLAB measurements of inclusive (e,A) cross sections as a function of outgoing lepton momentum may provide information on the nucleon spectral function in targets that will be relevant for the planned DUNE neutrino long-baseline experiment. They also provide an important testing ground for neutrino generators. We have therefore used the transport theoretical framework and code GiBUU to calculate the cross sections for the targets C, Ar and Ti. We compare the calculations with the experimental data. The overall agreement is good. Relatively small discrepancies appear mainly on the low-electronenergy side of the QE-peak where QE and 2p2h excitation processes overlap.

   nucl-exhep-exhep-phnucl-thPRC(2019)·14 citations
8. 08*

   Effects of the detector non-uniformity in pion directed flow measurement relative to the spectator plane by the NA49 experiment at the CERN SPS

   Oleg Golosov🇷🇺 · Evgeny Kashirin🇷🇺 · Viktor Klochkov🇩🇪 · Ilya Selyuzhenkov (for the NA49 Collaboration)🇷🇺

   Results are presented for directed flow of negatively charged pions measured relative to the spectator plane in Pb+Pb collisions at the beam energy 40A GeV recorded by the NA49 experiment at CERN. The measure-ments were performed as a function of rapidity and transverse momentum in two classes of collision centrality. The projectile spectator symmetry plane is estimated using the transverse segmentation of the forward hadron calorimeters. Analysis details related to event selection and particle dentification are provided along with a description of the procedure used to apply corrections for the limited detection efficiency. Additionally a systematic study of effects due to detector non-uniformity on pion directed flow measurement is presented.

   nucl-exhep-exEPJ Web Conf.(2019)·1 citation
9. 09*

   Comparing a few distributions of transverse momenta in high energy collisions

   Qi Wang🇨🇳 · Pei-Pin Yang🇨🇳 · Fu-Hu Liu🇨🇳

   Transverse momentum spectra of particles produced in high energy collisions are very important due to their relations to the excitation degree of interacting system. To describe the transverse momentum spectra, one can use more than one probability density functions of transverse momenta, which are simply called the functions or distributions of transverse momenta in some cases. In this paper, a few distributions of transverse momenta in high energy collisions are compared with each other in terms of plots to show some quantitative differences. Meanwhile, in the framework of Tsallis statistics, the distributions of momentum components, transverse momenta, rapidities, and pasudorapidities are obtained according to the analytical and Monte Carlo methods. These analyses are useful to understand carefully different distributions in high energy collisions.

   ↳ hep-phhep-exnucl-exnucl-thResults Phys.(2019)·6 citations
10. 10*

    Inclusive dijet photoproduction in ultraperipheral heavy-ion collisions at the CERN LHC in next-to-leading order QCD

    V. Guzey (Jyvaskyla U. & Helsinki U. & St. Petersburg, INP)🇷🇺 · M. Klasen (Munster U., ITP)🇩🇪

    We compute the cross section of inclusive dijet photoproduction in ultraperipheral Pb-Pb collisions at the LHC using next-to-leading order perturbative QCD. We demonstrate that our theoretical calculations provide a good description of various kinematic distributions measured by the ATLAS collaboration. We find that the calculated dijet photoproduction cross section is sensitive to nuclear modifications of parton distribution functions (PDFs) at the level of 10 to 20%. Hence, this process can be used to reduce uncertainties in the determination of these nuclear PDFs, whose current magnitude is comparable to the size of the calculated nuclear modifications of the dijet photoproduction cross section.

    ↳ hep-phnucl-exPRC(2019)·43 citations
11. 11*

    Density Changes in Low Pressure Gas Targets for Electron Scattering Experiments

    S. N. Santiesteban · S. Alsalmi · D. Meekins · J. Bane · S. Barcus · J. Campbell · J. Castellanos · R. Cruz-Torres · H. Dai · T. Hague · F. Hauenstein · D. W. Higinbotham and 12 other authors

    A system of modular sealed gas target cells has been developed for use in electron scattering experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). This system was initially developed to complete the MARATHON experiment which required, among other species, tritium as a target material. Thus far, the cells have been loaded with the gas species 3H, 3He, 2H, 1H and 40Ar and operated in nominal beam currents of up to 22.5 uA in Jefferson Lab's Hall A. While the gas density of the cells at the time of loading is known, the density of each gas varies uniquely when heated by the electron beam. To extract experimental cross sections using these cells, density dependence on beam current of each target fluid must be determined. In this study, data from measurements with several beam currents within the range of 2.5 to 22.5 uA on each target fluid are presented. Additionally, expressions for the beam current dependent fluid density of each target are developed.

    ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2019)·33 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.