Mon·Apr 29, 2019Monday·April 29, 2019

1. 01*

   Improved determination of thermal cross section of 14N(n,p)14C for the neutron lifetime measurement

   R. Kitahara🇯🇵 · K. Hirota🇯🇵 · S. Ieki🇯🇵 · T. Ino🇯🇵 · Y. Iwashita🇯🇵 · M. Kitaguchi🇯🇵 · J. Koga🇯🇵 · K. Mishima🇯🇵 · A. Morishita🇯🇵 · N. Nagakura🇯🇵 · H. Oide🇯🇵 · H. Otono🇯🇵 and 12 other authors

   In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated by the neutron decay rate and the incident neutron flux. The flux is obtained due to counting the protons emitted from the neutron absorption reaction of ${}^3\mathrm{He}$ gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of ${}^3\mathrm{He}$ in the mixture. In order to improve the accuracy of the number density of the ${}^3\mathrm{He}$ nuclei, we suggested to use the ${}^{14}\mathrm{N}(\mathrm{n},\mathrm{p}){}^{14}\mathrm{C}$ reaction as a reference because this reaction involves similar kinetic energy as the ${}^3\mathrm{He}(\mathrm{n},\mathrm{p}){}^3\mathrm{H}$ reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper, we report the most accurate experimental value of the cross section of the ${}^{14}\mathrm{N}(\mathrm{n},\mathrm{p}){}^{14}\mathrm{C}$ reaction at a neutron velocity of 2200 m/s, measured relative to the ${}^3\mathrm{He}(\mathrm{n},\mathrm{p}){}^3\mathrm{H}$ reaction. The result was 1.868 $\pm$ 0.003 (stat.) $\pm$ 0.006 (sys.) b. Additionally, the cross section of the ${}^{17}\mathrm{O}(\mathrm{n},\alpha ){}^{14}\mathrm{C}$ reaction at the neutron velocity is also redetermined as 249 $\pm$ 6 mb.

   nucl-exhep-exphysics.ins-detPTEP(2019)·4 citations
2. 02*

   What can we learn from transfer and how is best to do it?

   Wilton N. Catford🇬🇧

   An overview of the experimental aspects of nucleon transfer reactions with radioactive beams is presented, aimed principally at a researcher who is beginning their work in this area. Whilst the physics motivation and the means of theoretical interpretation are briefly described, the emphasis is on the experimental techniques and the quantities that can be measured. General features of the reactions which affect experimental design are highlighted and explained. A range of experimental choices for performing the experiments is described, and the reasons for making the different choices are rationalised and discussed. It is often useful to detect gamma-rays from electromagnetic transitions in the final nucleus, both to improve the precision and resolution of the excitation energy measurements and to assist in the identification of the observed levels. Several aspects related to gamma-ray detection and angular correlations are therefore included. The emphasis is on single-nucleon transfer reactions, and mostly on (d,p) transfer to produce nuclei that are more neutron-rich, but there are also brief discussions of other types of transfer reactions induced by both light ions and heavy ions.

   nucl-exLect.Notes Phys.·6 citations
3. 03*

   Multiparticle correlation studies in pPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV

   CMS Collaboration

   The second- and third-order azimuthal anisotropy Fourier harmonics of charged particles produced in pPb collisions, at $\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV, are studied over a wide range of event multiplicities. Multiparticle correlations are used to isolate global properties stemming from the collision overlap geometry. The second-order "elliptic" harmonic moment is obtained with high precision through four-, six-, and eight-particle correlations and, for the first time, the third-order "triangular" harmonic moment is studied using four-particle correlations. A sample of peripheral PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV that covers a similar range of event multiplicities as the pPb results is also analyzed. Model calculations of initial-state fluctuations in pPb and PbPb collisions can be directly compared to the high precision experimental results. This work provides new insight into the fluctuation-driven origin of the $v_3$ coefficients in pPb and PbPb collisions, and into the dominating overall collision geometry in PbPb collisions at the earliest stages of heavy ion interactions.

   ↳ hep-exnucl-exPRC(2020)·35 citations
4. 04*

   Possibility to study pentaquark states $P_c(4312),P_c(4440)$, and $P_c(4457)$ in $\gamma p\to J/\psi p$ reaction

   Xiao-Yun Wang🇨🇳 · Xu-Rong Chen🇨🇳 · Jun He🇨🇳

   Inspired by the observation of the pentaquark states $P_c(4312),P_c(4440)$ and $P_c(4457)$ at LHCb, photoproduction of these three $P_c$ states via the interaction $\gamma p\to J/\psi p$ is investigated in an effective Lagrangian approach. The $t$-channel Pomeron exchange diffractive process is considered as the main background for the $J/\psi$ photoproduction. The numerical results show that the theoretical cross section, which is calculated by assuming a branching ratio $Br[P_c\to J/\psi p]\simeq 3\%$, is consistent with the existing experimental data of the $\gamma p\to J/\psi p$ process. With such a branching ratio, if experimental precision reaches 0.1 nb within a bin of 100 MeV for photon energy, two peaks are expected to be obviously observed in the $J/\psi$ photoproduction. To observe the two-peak structure from $P_c(4440)$ and $P_c(4457)$, higher precision, about 0.1nb/10 MeV, is required to distinguish two close pentaquarks. If the physical branching ratio is larger, the requirement of experimental precision will be reduced. The differential cross sections for reaction $\gamma p\to J/\psi p$ are also present. It is found that the $t$-channel Pomeron exchange provides a sharp increase at extreme forward angles and gives a sizable contribution at most energy points, while the contributions from the $s$-channel $P_c$ exchanges play important roles at threshold energies. The experimental measurement of the $\gamma p\to J/\psi p$ process in the near-threshold energy region around $E_{\gamma }\simeq 9.4-10.5$ GeV is suggested, and is accessible at CEBAF@JLab and COMPASS.

   ↳ hep-phnucl-exnucl-thPRD(2019)·73 citations
5. 05*

   Associated Quarkonium Hadroproduction at High-Energy Colliders

   Nodoka Yamanaka🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Hua-Sheng Shao🇫🇷 · Yu-Jie Zhang🇨🇳

   Quarkonium production in proton-proton collision is interesting in profiling the partons inside the nucleon. Recently, the impact of double parton scatterings (DPSs) was suggested by experimental data of associated quarkonium production (J/psi+Z, J/psi+W, and J/psi+J/psi) at the LHC and Tevatron, in addition to single parton scatterings (SPSs). In this proceedings contribution, we review the extraction of the effective parameter of the DPS through the evaluation of the SPS contributions under quark-hadron duality.

   ↳ hep-phhep-exnucl-exnucl-thJPS Conf.Proc.(2019)·0 citations
6. 06*

   Higgs boson production in photon-photon interactions with proton, light-ion, and heavy-ion beams at current and future colliders

   David d'Enterria🇨🇭 · Daniel E. Martins🇧🇷 · Patricia Rebello Teles🇧🇷

   The production of the Higgs boson in photon-photon interactions with proton and nucleus beams at three planned or proposed future CERN colliders --- the high-luminosity Large Hadron Collider (HL-LHC), the high-energy LHC (HE-LHC), and the Future Circular Collider (FCC) --- is studied. The cross sections for the process AA$\stackrel{\gamma \gamma }{\to }$(A)H(A), with the ions A surviving the interaction and the Higgs scalar exclusively produced, are computed with MadGraph 5 modified to include the corresponding elastic $\gamma$ fluxes, for Pb-Pb, Xe-Xe, Kr-Kr, Ar-Ar, O-O, p-Pb, and p-p over the nucleon-nucleon collision energy range $\sqrt{s}\approx 3$--100 TeV. Simulations of the $\gamma \gamma \to H\to b\bar{b}$ decay mode --- including realistic (mis)tagging and reconstruction efficiencies for the final-state b-jets, as well as appropriate kinematical selection criteria to reduce the similarly computed $\gamma \gamma \to b\bar{b},c\bar{c},q\bar{q}$ continuum backgrounds --- have been carried out. Taking into account the expected luminosities for all systems, the yields and significances for observing the Higgs boson in ultraperipheral collisions (UPCs) are estimated. At the HL-LHC and HE-LHC, the colliding systems with larger Higgs significance are Ar-Ar(6.3 TeV) and Kr-Kr(12.5 TeV) respectively, but $3\sigma$ evidence for two-photon Higgs production would require 200 and 30 times larger integrated luminosities than those planned today at both machines. Factors of ten can be gained by running for a year, rather than the typical 1-month heavy-ion LHC operation, but the process will likely remain unobserved until a higher energy hadron collider, such as the FCC, is built. In the latter machine, the $5\sigma$ observation of Higgs production in UPCs is feasible in just the first nominal run of Pb-Pb and p-Pb collisions at $\sqrt{s}=39$ and 63 TeV respectively.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·21 citations
7. 07*

   Landau and Eckart frames for relativistic fluids in nuclear collisions

   Akihiko Monnai🇯🇵

   The quark matter created in relativistic nuclear collisions is interpreted as a nearly-perfect fluid. The recent efforts to explore its finite-density properties in the beam energy scan programs motivate one to revisit the issue of the local rest frame fixing in off-equilibrium hydrodynamics. I first investigate full second-order relativistic hydrodynamics in the Landau and the Eckart frames. Then numerical hydrodynamic simulations are performed to elucidate the effect of frame choice on flow observables in relativistic nuclear collisions. The results indicate that the flow can differ in the Landau and the Eckart frames but charged particle and net baryon rapidity distributions are mostly frame independent when off-equilibrium kinetic freeze-out is considered.

   ↳ nucl-thhep-phnucl-exPRC(2019)·23 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.