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Nuclear Theory·nucl-th

Monday·April 10, 2023

8 papers—2 primary·6 cross-listed

All8Primary2Cross-lists6
  1. 03

    [Submitted on 6 Apr 2023] (cross-list from hep-ph)

    Chromoelectric field correlator for quarkonium transport in the strongly coupled Yang-Mills plasma from AdS/CFT

    Govert Nijs🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Xiaojun Yao🇺🇸

    Previous studies have shown that a gauge-invariant correlation function of two chromoelectric fields connected by a straight timelike adjoint Wilson line encodes crucial information about quark-gluon plasma (QGP) that determines the dynamics of small-sized quarkonium in the medium. Motivated by the successes of holographic calculations to describe strongly coupled QGP, we calculate the analog gauge-invariant correlation function in strongly coupled supersymmetric Yang-Mills theory at finite temperature by using the AdS/CFT correspondence. Our results indicate that the transition processes between bound and unbound quarkonium states are suppressed in strongly coupled plasmas, and moreover, the leading contributions to these transition processes vanish in both the quantum Brownian motion and quantum optical limits of open quantum system approaches to quarkonia.

    Comments:
    82 pages, 11 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2304.03298 [pdf]
    JHEP(2023)·19 citations
  2. 04

    [Submitted on 6 Apr 2023] (cross-list from hep-ph)

    TMD Handbook

    Renaud Boussarie🇫🇷 · Matthias Burkardt🇺🇸 · Martha Constantinou🇺🇸 · William Detmold🇺🇸 · Markus Ebert🇺🇸 · Michael Engelhardt🇺🇸 · Sean Fleming🇺🇸 · Leonard Gamberg🇺🇸 · Xiangdong Ji🇺🇸 · Zhong-Bo Kang🇺🇸 · Christopher Lee🇺🇸 · Keh-Fei Liu🇺🇸 and 17 other authors

    This handbook provides a comprehensive review of transverse-momentum-dependent parton distribution functions and fragmentation functions, commonly referred to as transverse momentum distributions (TMDs). TMDs describe the distribution of partons inside the proton and other hadrons with respect to both their longitudinal and transverse momenta. They provide unique insight into the internal momentum and spin structure of hadrons, and are a key ingredient in the description of many collider physics cross sections. Understanding TMDs requires a combination of theoretical techniques from quantum field theory, nonperturbative calculations using lattice QCD, and phenomenological analysis of experimental data. The handbook covers a wide range of topics, from theoretical foundations to experimental analyses, as well as recent developments and future directions. It is intended to provide an essential reference for researchers and graduate students interested in understanding the structure of hadrons and the dynamics of partons in high energy collisions.

    Comments:
    471 pages, many figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2304.03302 [pdf]
    264 citations
  3. 05

    [Submitted on 6 Apr 2023] (cross-list from hep-ph)

    Back-to-back inclusive dijets in DIS at small : Gluon Weizsäcker-Williams distribution at NLO

    Paul Caucal🇫🇷 · Farid Salazar🇺🇸 · Björn Schenke🇺🇸 · Tomasz Stebel🇵🇱 · Raju Venugopalan🇺🇸

    In JHEP 11 (2022) 169, we performed the first complete computation of the back-to-back inclusive di-jet cross-section in Deeply Inelastic Scattering (DIS) at small to next-to-leading order (NLO) in the Color Glass Condensate effective field theory (CGC EFT). We demonstrate here that for di-jets with relative transverse momentum and transverse momentum imbalance , to leading power in , the cross-section for longitudinally polarized photons can be fully factorized into the product of a perturbative impact factor and the nonperturbative Weizsäcker-Williams (WW) transverse momentum dependent (TMD) gluon distribution to NLO accuracy. The impact factor can further be expressed as the product of a universal soft factor which resums Sudakov double and single logs in and a coefficient function given by a remarkably compact analytic expression. We show that in the CGC EFT the WW TMD satisfies a kinematically constrained JIMWLK renormalization group evolution in rapidity. This factorization formula is valid to all orders in for , where is the semi-hard saturation scale that grows with rapidity.

    Comments:
    73 pages, 8 figures, 1 table, revised version with extended discussion of running coupling effect to CSS evolution at small x
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2304.03304 [pdf]
    JHEP(2023)·69 citations
  4. 06

    [Submitted on 6 Feb 2023] (cross-list from physics.acc-ph)

    TOUCANS: a versatile Monte Carlo neutron transport code based on Geant4

    L. Thulliez🇫🇷 · B. Mom🇫🇷 · E. Dumonteil🇫🇷

    This paper reports the development of TOUCANS, a new Monte Carlo neutron transport code fully written using the Geant4 toolkit. It aims at modeling complex systems easily and rapidly, thanks to a simple key-value input file. While its main focus is the transport of low energy neutrons -- below 20 MeV -- using evaluated cross-section libraries, it also takes advantage of the state-of-the-art capabilities offered by Geant4 regarding the modeled cross-sections for practically all particles at all energies. Hence it gives access to non-specialists to a wide variety of applications involving different particles, such as for instance the simulation of compact accelerator based neutron sources (CANS) which initially motivated its development. It leverages on recent implementations performed within Geant4 to provide both shielding calculation capabilities (using Adaptive Multilevel Splitting, which is a fully automated variance reduction technique) and criticality calculation capabilities (to estimate the keff of a multiplicative system). It also benefits from a tight coupling with CADMesh to readily import CAD models, with NCrystal to extend the support of thermal neutron transport to crystals, with FIFRELIN to increase compound nucleus de-excitation accuracy, and with FUNZ to provide to the user parametric simulation capabilities (such as multi-objective algorithms, calculation of Pareto sets, etc). Thanks to recent improvements of the neutron physics within the Geant4 Neutron-HP package, the TOUCANS code can be considered on-par with industrial neutron transport codes such as Tripoli-4 or MCNP in term of neutron physics accuracy. Its sources should be released soon amongst Geant4 advanced examples.

    Comments:
    17 pages, 9 figures
    Subjects:
    Accelerator Physics (physics.acc-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2304.03678 [pdf]
    Nucl.Instrum.Meth.A(2023)·4 citations
  5. 07

    [Submitted on 7 Apr 2023] (cross-list from hep-ph)

    Medium induced gluon spectrum in dense inhomogeneous matter

    João Barata🇺🇸 · Xoán Mayo López🇪🇸 · Andrey V. Sadofyev🇪🇸 · Carlos A. Salgado🇪🇸

    We calculate the spectrum of gluons sourced by the branching of an energetic quark in the presence of an inhomogeneous QCD medium, focusing on the soft radiation limit. We take into account multiple soft interactions between the partons and matter, treating the transverse variations of its parameters within a gradient expansion. Thus, we derive the general form of the medium induced spectrum up to the first order in gradients, and consider its simplifying limits. In particular, we show that to the leading order in matter gradients and using the harmonic approximation for the scattering potential, the full gluon spectrum can be written in a compact closed form suitable for numerical evaluation. The final gluon transverse momentum tends to align along the anisotropy direction, resulting in a non-trivial azimuthal pattern in the jet substructure.

    Comments:
    28 pages, 3 figures, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2304.03712 [pdf]
    PRD(2023)·48 citations
  6. 08

    [Submitted on 7 Apr 2023] (cross-list from hep-ph)

    One-loop fermion-photon vertex in arbitrary gauge and dimensions: a novel approach

    Victor Miguel Banda Guzmán🇲🇽 · Adnan Bashir🇲🇽

    We compute one-loop electron-photon vertex with fully off-shell external momenta in an arbitrary covariant gauge and space-time dimension. There exist numerous efforts in literature where one-loop off-shell vertex is calculated by employing the standard first order Feynman rules in different covariant gauges and space-time dimensions of interest. The tensor structure which decomposes this three-point vertex into the components transverse and longitudinal to the photon momentum gets intertwined in this first order formalism. The Ward-Takahashi identity is explicitly invoked to untangle the two pieces and the results are expressed in a preferred basis of twelve spin-amplitudes. We propose a novel approach based upon an efficient combination of the first and second order formalisms of quantum electrodynamics to compute this one-loop vertex. Among some conspicuous advantages is the fact that this less known second order formalism separates the spin and scalar degrees of freedom of an electron interacting electromagnetically. More noticeably, the longitudinal and transverse contributions naturally disentangle from the onset in our approach. Moreover, this decomposition leads to identities between one-loop scalar Feynman integrals with higher powers in the propagators and shifted space-time dimensions that can be used to prove the Ward-Takahashi identity at one-loop order without the need to evaluate any Feynman integral. Additionally, this natural decomposition allows us to establish the gauge-independence of the Pauli form factor through explicit cancellations of scalar Feynman integrals that depend on the gauge parameter. These cancellations naturally lead to a compact expression for the Pauli form factor in arbitrary dimensions. Wherever necessary and insightful, we make comparisons with earlier works.

    Comments:
    14 pages, 3 Figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2304.03719 [pdf]
    PRD(2023)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE