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Nuclear Theory·nucl-th

Thursday·September 14, 2023

8 papers—2 primary·6 cross-listed

All8Primary2Cross-lists6
  1. 03

    Dissipation dynamics of a scalar field

    Laura Batini🇩🇪 · Eduardo Grossi🇮🇹 · Nicolas Wink🇩🇪

    We investigate the dissipation rate of a scalar field in the vicinity of the phase transition and the ordered phase, specifically within the universality class of model A. This dissipation rate holds significant physical relevance, particularly in the context of interpreting effective potentials as inputs for dynamical transport simulations, such as hydrodynamics. To comprehensively understand the use of effective potentials and other calculation inputs, such as the functional renormalization group, we conduct a detailed analysis of field dependencies. We solve the functional renormalization group equations on the Schwinger-Keldysh contour to determine the effective potential and dissipation rate for both finite and infinite volumes. Furthermore, we conduct a finite-size scaling analysis to calculate the dynamic critical exponent z. Our extracted value closely matches existing values from the literature.

    ↳ hep-thcond-mat.str-elhep-phnucl-thPRD(2023)·18 citations
  2. 04

    Extended SAID Partial-Wave Analysis of Pion Photoproduction

    William J. Briscoe🇺🇸 · Axel Schmidt🇺🇸 · Igor Strakovsky🇺🇸 · Ron L. Workman (GWU)🇺🇸 · Alfred Svarc (Rudjer Boskovic Institute)🇭🇷

    A unified Chew-Mandelstam description of single-pion photoproduction data, together with pion- and eta-hadroproduction data, has been extended to include measurements carried out over the last decade. We consider photo-decay amplitudes evaluated at the pole with particular emphasis on ng couplings and the influence of weighting on our fits. Both energy-dependent and single-energy analysis (energy-binned data) are considered.

    ↳ hep-phhep-exnucl-exnucl-thPRC(2023)·19 citations
  3. 05

    Novel relations for twist-3 tensor-polarized fragmentation functions in spin-1 hadrons

    Qin-Tao Song🇨🇳

    There are three types of fragmentation functions (FFs) which are used to describe the twist-3 cross sections of the hard semi-inclusive processes under QCD collinear factorization, and they are called intrinsic, kinematical, and dynamical FFs. In this work, we investigate the theoretical relations among these FFs for a tensor-polarized spin-1 hadron. Three Lorentz-invariance relations are derived by using the identities between the nonlocal quark-quark and quark-gluon-quark operators, which guarantee the frame independence of the twist-3 spin observables. The QCD equation of motion relations are also presented for the tensor-polarized FFs. In addition, we show that the intrinsic and kinematical twist-3 FFs can be decomposed into the contributions of twist-2 FFs and twist-3 three-parton FFs, and the latter are also called dynamical FFs. If one neglects the dynamical FFs, we can obtain relations which are analogous to the Wandzura-Wilczek relation. Then, the intrinsic and kinematical twist-3 FFs are expressed in terms of the leading-twist ones. Since the FFs of a spin-1 hadron can be measured at various experimental facilities in the near future, these theoretical relations will play an important role in the analysis of the collinear tensor-polarized FFs.

    ↳ hep-phnucl-thPRD(2023)·7 citations
  4. 06

    QCD phase diagram and equation of state in background electric fields

    Gergely Endrodi🇩🇪 · Gergely Marko🇩🇪

    The phase diagram and the equation of state of QCD is investigated in the presence of weak background electric fields by means of continuum extrapolated lattice simulations. The complex action problem at nonzero electric field is circumvented by a novel Taylor expansion, enabling the determination of the linear response of the thermal QCD medium to constant electric fields -- in contrast to simulations at imaginary electric fields, which, as we demonstrate, involve an infrared singularity. Besides the electric susceptibility of QCD matter, we determine the dependence of the Polyakov loop on the field strength to leading order. Our results indicate a plasma-type behavior with a negative susceptibility at all temperatures, as well as an increase in the transition temperature as the electric field grows.

    ↳ hep-lathep-phhep-thnucl-thPRD(2024)·22 citations
  5. 07

    eV-deep neutron bound states in nanocrystals

    Hao Tang · Guoqing Wang · Paola Cappellaro · Ju Li

    The nuclear strong force induces the widely studied neutron scattering states and MeV-energy nuclear bound states. Whether this same interaction could lead to low-energy bound states for a neutron in the nuclear force field of a cluster of nuclei is an open question. Here, we computationally demonstrate the existence of -eV-level neutronic bound states originating from nuclear interaction in nanocrystals with a spatial extent of tens of nanometers. These negative-energy neutron wavefunctions depend on the size, dimension, and nuclear spin polarization of the nanoparticles, providing engineering degrees of freedom for the artificial neutronic "molecule".

    ↳ quant-phnucl-thACS Nano(2024)·0 citations
  6. 08

    Collective excitations of a hot QCD medium in a time dependent background magnetic field

    Gowthama K K🇮🇳 · Vinod Chandra🇮🇳

    Collective modes within a hot Quantum Chromodynamics (QCD) medium are obtained from the polarization tensor, considering both constant and time-varying electromagnetic fields. In both scenarios, five complex modes emerge, reliant on the wave vector (), with electrical conductivity exerting significant influence. The impact of the modes on the energy loss of heavy quarks in the hot QCD medium with a background electromagnetic field has been studied by obtaining the induced electric field in terms of the polarization tensor while invoking Wong's equations. The findings are seen to be consistent with analogous approaches, reinforcing the significance of the results.

    ↳ hep-phnucl-thPRD(2023)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE