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Nuclear Theory·nucl-th

Thursday·August 25, 2016

5 papers—1 primary·4 cross-listed

All5Primary1Cross-lists4
  1. 01

    [Submitted on 24 Aug 2016]

    Study of W and Z Boson Production in Proton-Lead Collisions at the LHC with KP Nuclear Parton Distributions

    Peng Ru🇨🇳 · S. A. Kulagin🇷🇺 · R. Petti🇺🇸 · Ben-Wei Zhang🇨🇳

    We present a detailed study of the (pseudo)rapidity distributions of massive vector bosons produced in p+p and p+Pb collisions at the LHC within the next-to-leading order approximation in perturbative quantum chromodynamics. In particular, we discuss the impact of different cold nuclear matter effects on this process using the nuclear parton distributions calculated from the microscopic model developed by Kulagin and Petti (KP). This model was successfully applied to study nuclear effects in the deep-inelastic scattering and the Drell-Yan reactions off various (fixed) target nuclei. Results are compared with the recent CMS and ATLAS p+Pb data with \sqrt{s}=5.02 TeV per two colliding nucleons. We found an excellent agreement between the predictions of the KP model and the recent LHC data on W+- and Z0 production in p+Pb collisions, including the differential cross sections, the forward-backward asymmetries, and W charge asymmetry. We also discuss the sensitivity of the current and future LHC data to the underlying mechanisms responsible for the nuclear modifications of parton density functions.

    Comments:
    22 pages, 12 figures, text editing, final version to be published in Phys. Rev. D
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1608.06835 [pdf]
    PRD(2016)·36 citations
  2. 02

    [Submitted on 24 Aug 2016] (cross-list from hep-ph)

    Effects of -meson width on pion distributions in heavy-ion collisions

    Pasi Huovinen🇵🇱 · Pok Man Lo🇵🇱 · Michał Marczenko🇵🇱 · Kenji Morita🇯🇵 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    The influence of the finite width of meson on the pion momentum distribution is studied quantitatively in the framework of the S-matrix approach combined with a blast-wave model to describe particle emissions from an expanding fireball. We find that the proper treatment of resonances which accounts for their production dynamics encoded in data for partial wave scattering amplitudes can substantially modify spectra of daughter particles originating in their two body decays. In particular, it results in an enhancement of the low- pions from the decays of mesons which improves the quantitative description of the pion spectra in heavy ion collisions obtained by the ALICE collaboration at the LHC energy.

    Comments:
    5 pages, 2 figures, version appeared in phys. lett. b
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1608.06817 [pdf]
    PLB(2017)·39 citations
  3. 03

    [Submitted on 24 Aug 2016] (cross-list from hep-ph)

    On Friedrichs Model with Two Continuum States

    Zhiguang Xiao🇨🇳 · Zhi-Yong Zhou🇨🇳

    The Friedrichs model with one discrete state coupled to more than one continuum is studied. The exact eigenstates for the full Hamiltonian can be solved explicitly. The discrete state is found to generate more than one virtual state pole or more than one pair of resonance poles in different Riemann sheets in different situations. The form factors could also generate new states on different sheets. All these states can appear in the generalized completeness relation.

    Comments:
    13 pages, 9 figures, publication version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1608.06833 [pdf]
    J.Math.Phys.(2017)·27 citations
  4. 04

    [Submitted on 24 Aug 2016] (cross-list from hep-lat)

    On the strength of the anomaly at the chiral phase transition in QCD

    Bastian B. Brandt🇩🇪 · Anthony Francis🇨🇦 · Harvey B. Meyer🇩🇪 · Owe Philipsen🇩🇪 · Daniel Robaina🇩🇪 · Hartmut Wittig🇩🇪

    We study the thermal transition of QCD with two degenerate light flavours by lattice simulations using -improved Wilson quarks. Temperature scans are performed at a fixed value of , where is the lattice spacing and the temperature, at three fixed zero-temperature pion masses between 200 MeV and 540 MeV. In this range we find that the transition is consistent with a broad crossover. As a probe of the restoration of chiral symmetry, we study the static screening spectrum. We observe a degeneracy between the transverse isovector vector and axial-vector channels starting from the transition temperature. Particularly striking is the strong reduction of the splitting between isovector scalar and pseudoscalar screening masses around the chiral phase transition by at least a factor of three compared to its value at zero temperature. In fact, the splitting is consistent with zero within our uncertainties. This disfavours a chiral phase transition in the universality class.

    Comments:
    46 pages, 16 figure, 12 tables; v2: typos corrected; enhanced explanations and discussions; included study of systematic effects for the extraction of screening masses; conclusions unchanged; new version to match published version
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1608.06882 [pdf]
    JHEP(2016)·113 citations
  5. 05

    [Submitted on 24 Aug 2016] (cross-list from nucl-ex)

    Neutron-rich rare isotope production from projectile fission of heavy beams in the energy range of 20 MeV/nucleon

    N. Vonta · G.A. Souliotis · W.D. Loveland · Y.K. Kwon · K. Tshoo · S.C. Jeong · M. Veselsky · A. Bonasera · A. Botvina

    We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Transfer model (DIT), or with the microscopic Constrained Molecular Dynamics model (CoMD). The deexcitation/fission of the hot heavy projectile fragments is performed with the Statistical Mul- tifragmentation Model (SMM). We compared our model calculations with our previous experimental projectile-fission data of 238U (20 MeV/nucleon)+208Pb and 197Au (20 MeV/nucleon)+197Au and found an overall reasonable agreement. Our study suggests that projectile fission following periph- eral heavy-ion collisions at this energy range offers an effective route to access very neutron-rich rare isotopes toward and beyond the astrophysical r-process path.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1608.06892 [pdf]
    PRC(2016)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE