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Nuclear Theory·nucl-th

Thursday·April 24, 2025

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    [Submitted on 22 Apr 2025] (cross-list from hep-ph)

    A New Look At Small- Helicity Phenomenology: Investigating Uncertainties And The Impact Of Polarized Proton-proton Data

    Nicholas Baldonado🇺🇸

    This dissertation highlights the contributions I have made to the field of theoretical nuclear physics, specifically in high-energy Quantum Chromodynamics (QCD). High-energy QCD is a robust subject and my research is refined to the sub-field of small- spin physics; small- physics is characterized by high-energy and density collisions and is well-suited for the Color Glass Condensate (CGC) effective field theory. Small- spin physics takes the ultra-relativistic description of high-energy QCD and gives special attention to spin-dependent interactions suppressed by powers of the center-of-mass energy. My expertise lies in exploring the theory and phenomenology relating to the KPS-CTT small- helicity evolution equations, a rubric that allows one to make predictions of the quarks' and gluons' distributions of spin at small-. These predictions are heavily influenced by the initial conditions of the evolution, and the initial conditions are determined through analyses of world polarized data. My contributions focus on Bayesian parameter analysis, numerical and analytical calculations to discretize and cross-check the evolution equations, and the incorporation of a new observable into the pool of analyzed data. The results of such work show that the net amount of spin from quarks and gluons in the small- regime is predicted to be negative and/or potentially small; an analysis of polarized deep-inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) data resulted in a net small- spin prediction that can be large and negative, but new results with the inclusion of data for single-inclusive jet production in polarized proton-proton () collisions now estimate that the net amount of parton spin at small is small, with 1- uncertainty that spans zero.

    Comments:
    184 pages, 5 tables, 44 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2504.16284 [pdf]
    0 citations
  2. 04

    [Submitted on 23 Apr 2025] (cross-list from hep-ph)

    Criteria of Renormalizability in Effective Field Theories

    A. M. Gasparyan🇩🇪 · E. Epelbaum🇩🇪

    Any effective field theory relies on power counting rules that allow one to perform a systematic expansion of calculated quantities in terms of some soft scales. However, a naive power counting can be violated due to the presence of various hard scales in a given scheme. A typical example of such a scale is an ultraviolet regulator. This issue is particularly challenging when the interaction is nonperturbative. The power counting is expected to be restored in the course of renormalization, that is by redefining bare low-energy constants in the effective Lagrangian. Whether this procedure eventually leads to a self-consistent framework is not a priory obvious. We discuss various criteria of renormalizability in application to nuclear chiral effective field theory and provide several instructive counterexamples.

    Comments:
    13 pages, talk presented at the 11th International Workshop on Chiral Dynamics (CD2024), 26-30 August, 2024, Ruhr University Bochum, Germany
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2504.16512 [pdf]
    PoS(2026)·2 citations
  3. 05

    [Submitted on 23 Apr 2025] (cross-list from hep-ph)

    Medium-induced coherent gluon radiation for processes with general kinematics

    Greg Jackson🇫🇷 · Stéphane Peigné🇫🇷 · Kazuhiro Watanabe🇯🇵

    High-energy proton-nucleus (pA) collisions offer valuable insight into the role of cold nuclear matter effects in hadron production. In particular, multiple rescatterings of an incoming parton by the nuclear target are known to induce the radiation of many soft gluons. Hadron production is affected by fully coherent energy loss (FCEL), owing to those radiated gluons with a long formation time. Here we present a recently derived formula for the induced single soft gluon radiation spectrum beyond leading logarithmic accuracy, whose main features are demonstrated with the example of scattering.

    Comments:
    6 pages, 1 figure. Proceedings of the 12th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2024), September 22-27, 2024, Nagasaki, Japan; v2: minor revisions
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2504.16647 [pdf]
    EPJ Web Conf.(2025)·0 citations
  4. 06

    [Submitted on 23 Apr 2025] (cross-list from hep-ph)

    Particles in finite volumes and a toy model of decaying neutrons

    Christian Käding🇦🇹

    It is well-known that the momentum spectra of particles confined to finite spatial volumes deviate from the continuous spectra used for unconfined particles. In this article, we consider real scalar particles confined to finite volumes with periodic boundary conditions, such that the particles' spectra are discrete. We directly compute the density matrices describing the decay processes and , and subsequently derive expressions for the decay probabilities both for confined and unconfined particles. The latter decay process is used as a rough toy model for a neutron decaying into a proton, an electron, and an anti-electron neutrino. We propose that finite volume effects can have an impact on the outcomes of experiments measuring the neutron lifetime. In addition, our findings at the toy model level suggest that taking into account possible initial correlations between neutrons and their daughter particles might be relevant as well.

    Comments:
    28 pages, 3 figures, as published in EPJC
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2504.16784 [pdf]
    EPJC(2025)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE