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Nuclear Theory·nucl-th

Friday·March 10, 2023

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 08

    [Submitted on 2 Mar 2023] (cross-list from cond-mat.quant-gas)

    Unitary interaction geometries in few-body systems

    Lorenzo Contessi🇫🇷 · Johannes Kirscher🇮🇳 · Manuel Pavon Valderrama🇨🇳

    We consider few-body systems in which only a certain subset of the particle-particle interactions is resonant. We characterize each subset by a {\it unitary graph} in which the vertices represent distinguishable particles and the edges resonant 2-body interactions. Few-body systems whose unitary graph is connected will collapse unless a repulsive 3-body interaction is included. We find two categories of graphs, distinguished by the kind of 3-body repulsion necessary to stabilize the associated system. Each category is characterized by whether the graph contains a loop or not: for tree-like graphs (graphs containing a loop) the 3-body force renormalizing them is the same as in the 3-body system with two (three) resonant interactions. We show numerically that this conjecture is correct for the 4-body case as well as for a few 5-body configurations. We explain this result in the 4-body sector qualitatively by imposing Bethe-Peierls boundary conditions on the pertinent Faddeev-Yakubovsky~decomposition of the wave function.

    Comments:
    17 pages, 8 figures
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2303.01312 [pdf]
    PRA(2024)·1 citation
  2. 09

    [Submitted on 8 Mar 2023] (cross-list from hep-ph)

    Exciting Ions: a Systematic Treatment of Ultraperipheral Heavy Ion Collisions with Nuclear Breakup

    L. A. Harland-Lang🇬🇧

    We present an updated theoretical treatment of ultraperipheral collisions (UPCs) of heavy ions, within the SuperChic Monte Carlo generator. This in particular accounts for mutual ion excitation through additional photon exchanges between the colliding ions. This effect occurs frequently in UPCs, and indeed can be (and has been) measured in data through the use of zero degree calorimeter (ZDC) detectors installed in the far forward region. The theoretical approach presented here accounts for the non-trivial and non-negligible impact such ion dissociation has on the measured cross sections and distributions of the produced particles in the central detectors. This builds on previous work, whereby the survival factor probability of no additional inelastic ion-ion scattering due to the strong interaction, and its kinematic impact, are also accounted for within the same overall framework. We compare to data from ATLAS and CMS at the LHC, and STAR at RHIC, and find in general encouraging agreement for a range of observables and ZDC neutron tags, with some room for further improvement, suggesting the inclusion of higher order QED effects and/or tuning of the the cross section may be desirable. Overall, this gives confidence in the approach considered here and for applications to new phenomena within and beyond the Standard Model.

    Comments:
    27 pages, 12 figures. Version that appears in PRD
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2303.04826 [pdf]
    PRD(2023)·21 citations
  3. 10

    [Submitted on 8 Mar 2023] (cross-list from quant-ph)

    Quantum computing with and for many-body physics

    Thomas Ayral🇫🇷 · Pauline Besserve🇫🇷 · Denis Lacroix🇫🇷 · Edgar Andres Ruiz Guzman🇫🇷

    Quantum computing technologies are making steady progress. This has opened new opportunities for tackling problems whose complexity prevents their description on classical computers. A prototypical example of these complex problems are interacting quantum many-body systems: on the one hand, these systems are known to become rapidly prohibitive to describe using classical computers when their size increases. On the other hand, these systems are precisely those which are used in the laboratory to build quantum computing platforms. This arguably makes them one of the most promising early use cases of quantum computing. In this review, we explain how quantum many-body systems are used to build quantum processors, and how, in turn, current and future quantum processors can be used to describe large many-body systems of fermions such as electrons and nucleons. The review includes an introduction to analog and digital quantum devices, the mapping of Fermi systems and their Hamiltonians onto qubit registers, as well as an overview of methods to access their static and dynamical properties. We also highlight some aspects related to entanglement, and touch on the description, influence and processing of decoherence in quantum devices.

    Subjects:
    Quantum Physics (quant-ph); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
    arXiv:
    2303.04850 [pdf]
    EPJA(2023)·62 citations
  4. 11

    [Submitted on 8 Mar 2023] (cross-list from hep-ph)

    The resolution to the problem of consistent large transverse momentum in TMDs

    J. O. Gonzalez-Hernandez🇮🇹 · T. Rainaldi🇺🇸 · T. C. Rogers🇺🇸

    Parametrizing TMD parton densities and fragmentation functions in ways that consistently match their large transverse momentum behavior in standard collinear factorization has remained notoriously difficult. We show how the problem is solved in a recently introduced set of steps for combining perturbative and nonperturbative transverse momentum in TMD factorization. Called a ``bottom-up'' approach in a previous article, here we call it a ``hadron structure oriented'' (HSO) approach to emphasize its focus on preserving a connection to the TMD parton model interpretation. We show that the associated consistency constraints improve considerably the agreement between parametrizations of TMD functions and their large- behavior, as calculated in collinear factorization. The procedure discussed herein will be important for guiding future extractions of TMD parton densities and fragmentation functions and for testing TMD factorization and universality. We illustrate the procedure with an application to semi-inclusive deep inelastic scattering (SIDIS) structure functions at an input scale , and we show that there is improved consistency between different methods of calculating at moderate transverse momentum. We end with a discussion of plans for future phenomenological applications.

    Comments:
    27 pages, 8 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2303.04921 [pdf]
    PRD(2023)·19 citations
  5. 12

    [Submitted on 9 Mar 2023] (cross-list from hep-th)

    Pseudogauge freedom and the SO(3) algebra of spin operators

    Sourav Dey🇮🇳 · Wojciech Florkowski🇵🇱 · Amaresh Jaiswal🇮🇳 · Radoslaw Ryblewski🇵🇱

    The energy-momentum and spin tensors for a given theory can be replaced by alternative expressions that obey the same conservation laws for the energy, linear momentum, as well as angular momentum but, however, differ by the local redistribution of such quantities (with global energy, linear momentum, and angular momentum remaining unchanged). This arbitrariness is described in recent literature as the pseudogauge freedom or symmetry. In this letter, we analyze several pseudogauges used to formulate the relativistic hydrodynamics of particles with spin 1/2 and conclude that the canonical version of the spin tensor has an advantage over other forms as only the canonical definition defines the spin operators that fulfill the SO(3) algebra of angular momentum. This result sheds new light on the results encountered in recent papers demonstrating pseudogauge dependence of various physical quantities. It indicates that for spin-polarization observables, the canonical version is fundamentally better suited for building a connection between theory and experiment.

    Comments:
    6 pages
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2303.05271 [pdf]
    PLB(2023)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE