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Nuclear Theory·nucl-th

Monday·August 28, 2017

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 04

    [Submitted on 24 Aug 2017] (cross-list from hep-ph)

    Double, triple, and -parton scatterings in high-energy proton and nuclear collisions

    David d'Enterria🇨🇭 · Alexander Snigirev🇷🇺

    The framework to compute the cross sections for the production of particles with high mass and/or large transverse momentum in double- (DPS), triple- (TPS), and in general -parton scatterings, from the corresponding single-parton () values in high-energy proton-proton, proton-nucleus, and nucleus-nucleus is reviewed. The basic parameter of the factorized -parton scattering ansatz is an effective cross section encoding all unknowns about the underlying generalized -parton distribution in the proton (nucleon). In its simplest and most economical form, the parameter can be derived from the transverse parton profile of the colliding protons and/or nucleus, using a Glauber approach. Numerical examples for the cross sections and yields expected for the concurrent DPS or TPS production of heavy-quarks, quarkonia, and/or gauge bosons in proton and nuclear collisions at LHC and Future Circular Collider (FCC) energies are provided. The obtained cross sections are based on perturbative QCD predictions for at next-to-leading-order (NLO) or next-to-NLO (NNLO) accuracy including, when needed, nuclear modifications of the corresponding parton densities.

    Comments:
    33 pages, 9 figures. Review chapter in "Multiple parton interactions at the LHC", Bartalini & Gaunt eds., World Scientific
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1708.07519 [pdf]
    Adv.Ser.Direct.High Energy Phys.(2018)·54 citations
  2. 05

    [Submitted on 24 Aug 2017] (cross-list from hep-ph)

    Elastic scattering of a quark from a color field: longitudinal momentum exchange

    Jamal Jalilian-Marian🇺🇸

    Perturbative QCD in the small Bjorken limit can be formulated as an effective theory known as the Color Glass Condensate (CGC) formalism. The CGC formalism takes into account the dynamics of large gluon densities at small and has been successfully applied to Deep Inelastic Scattering (DIS) and particle production in high energy hadronic and nuclear collisions in the small kinematic region. The effective degrees of of freedom in CGC are Wilson lines which enter in the effective quark (and gluon) propagators and re-sum multiple soft scatterings from the small gluon field of the target. It is however known that the CGC effective theory breaks down when one probes the moderately large (high ) kinematics where collinear factorization and DGLAP evolution of parton distribution functions should be the right framework. Here we propose a general framework which may allow one to eventually unify the two approaches and to calculate pQCD cross sections in both small and large Bjorken regions. We take the first step towards this goal by deriving an expression for the quark propagator in a background field which includes scatterings from both small and large modes of the gluon field of the target. We describe how this quark propagator can be used to calculate QCD structure functions and at all and thus generalize the dipole model of DIS. We outline this approach can also be used to extend the so-called hybrid approach to particle production in the forward rapidity region of high energy hadronic and nuclear collisions to all and regions and speculate on how one may apply the same techniques to extend the McLerran-Venugopalan effective action used in high energy heavy ion collisions to include high physics.

    Comments:
    22 pages, 14 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1708.07533 [pdf]
    PRD(2017)·47 citations
  3. 06

    [Submitted on 22 Aug 2017] (cross-list from quant-ph)

    Monotonic properties of the shift and penetration factors

    Carl R. Brune · Gerald M. Hale · Mark W. Paris

    We study derivatives of the shift and penetration factors of collision theory with respect to energy, angular momentum, and charge. Definitive results for the signs of these derivatives are found for the repulsive Coulomb case. In particular, we find that the derivative of the shift factor with respect to energy is positive for the repulsive Coulomb case, a long anticipated but heretofore unproven result. These results are closely connected to the properties of the sum of squares of the regular and irregular Coulomb functions; we also present investigations of this quantity.

    Comments:
    13 pages, 1 figure
    Subjects:
    Quantum Physics (quant-ph); Mathematical Physics (math-ph); math.CA (math.CA); math.MP (math.MP); Nuclear Theory (nucl-th)
    arXiv:
    1708.07554 [pdf]
    PRC(2018)·2 citations
  4. 07

    [Submitted on 25 Aug 2017] (cross-list from hep-ph)

    Single- and double-scattering production of four muons in ultraperipheral PbPb collisions at the Large Hadron Collider

    Andreas van Hameren🇵🇱 · Mariola Klusek-Gawenda🇵🇱 · Antoni Szczurek🇵🇱

    We discuss production of two pairs in ultraperipheral ultrarelativistic heavy ion collisions at the LHC. We take into account electromagnetic (two-photon) double-scattering production and for a first time direct production of four muons in one scattering. We study the unexplored process . We present predictions for total and differential cross sections. Measurable nuclear cross sections are obtained and corresponding differential distributions and counting rates are presented.

    Comments:
    13 pages, 11 figures, 1 table
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    1708.07742 [pdf]
    PLB(2018)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE