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Nuclear Theory·nucl-th

Thursday·December 29, 2022

12 papers—5 primary·7 cross-listed

All12Primary5Cross-lists7
  1. 06

    Neutrino oscillations in Quantum Field Theory

    Sergey Kovalenko🇨🇱 · Fedor Simkovic🇸🇰

    We propose a Quantum Field Theory (QFT) approach to neutrino oscillations in vacuum. The neutrino emission and detection are identified with the charged-current vertices of a single second-order Feynman diagram for the underlying process, enclosing neutrino propagation between these two points. The key point of our approach is the definition of the space-time setup typical for neutrino oscillation experiments, implying macroscopically large but finite volumes of the source and detector separated by a sufficiently large distance . We derive an -dependent master formula for the charged lepton production rate, which provides the QFT basis for the analysis of neutrino oscillations. Our formula depends on the underlying process and is not reducible to the conventional approach resorting to the concept of neutrino oscillation probability, which originates from non-relativistic quantum mechanics (QM). We demonstrate that for some particular choice of the underlying process our QFT formula approximately coincides with the conventional one under some assumptions.

    ↳ hep-phhep-exhep-thnucl-th6 citations
  2. 07

    Testing the -nuclear potential in pion-induced meson production on nuclei near threshold

    E. Ya. Paryev🇷🇺

    The near-threshold pion-induced production off nuclei has been studied in the kinematical conditions of the HADES experiment using a collision model based on the nuclear spectral function. Starting from the elementary reaction , absolute differential and integral cross sections for the production of mesons off a light carbon and a heavy tungsten target have been calculated and compared to the recently reported experimental cross sections. The absolute cross section values are shown to be sensitive to the effective nuclear scalar and neutron potentials while the transparency ratio is governed by the absorption cross section. The experimental data are found to be consistent with an attractive -nucleus potential of -(50--100) MeV at normal nuclear matter density and an effective absorption cross section of 12--25 mb. The extracted -nucleus potential is deeper than previous theoretical and experimental findings as well as those obtained in the present work within the () approximation with accounting for Pauli correlations from the spin-averaged - scattering length reported in a recent ALICE experiment.

    ↳ nucl-exhep-exnucl-thNPA(2023)·9 citations
  3. 08

    Comprehensive theory of the Lamb shift in light muonic atoms

    K. Pachucki🇵🇱 · V. Lensky🇩🇪 · F. Hagelstein🇩🇪 · S. S. Li Muli🇩🇪 · S. Bacca🇩🇪 · R. Pohl🇩🇪

    A comprehensive theory of the Lamb shift in light muonic atoms such as H, D, He, and He is presented, with all quantum electrodynamic corrections included at the precision level constrained by the uncertainty of nuclear structure effects. This analysis can be used in the global adjustment of fundamental constants and in the determination of nuclear charge radii. Further improvements in the understanding of electromagnetic interactions of light nuclei will allow for a promising test of fundamental interactions by comparison with ``normal" atomic spectroscopy, in particular, with H-D and He-He isotope shifts.

    ↳ physics.atom-phnucl-exnucl-thRMP(2024)·57 citations
  4. 09

    Neutral pion mass in warm magnetized medium within Linear Sigma Model coupled to Quarks framework

    Aritra Das🇮🇳 · Najmul Haque🇮🇳

    We study the neutral pion mass in the presence of an external arbitrary magnetic field in the framework of the linear sigma model coupled to quark (LSMq) at finite temperature. In doing so, we have calculated the pion self-energy, constructed the dispersion equation via re-summation, and solved the dispersion relation at zero three momentum limit. In calculating the pion mass, we have included meson self-coupling's thermal and magnetic contribution and approximate chiral order parameter . We report that the mass decreases with the magnetic field and increases with temperature.

    ↳ hep-phhep-latnucl-thPRD(2023)·6 citations
  5. 10

    Equation of state and speed of sound of isospin-asymmetric QCD on the lattice

    Bastian B. Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrodi🇩🇪

    We determine the QCD equation of state at nonzero temperature in the presence of an isospin asymmetry between the light quark chemical potentials on the lattice. Our simulations employ flavors of dynamical staggered quarks at physical masses, using three different lattice spacings. The main results are based on a two-dimensional spline interpolation of the isospin density, from which all relevant quantities can be obtained analytically. In particular, we present results for the pressure, the interaction measure, the energy and entropy densities, as well as the speed of sound. Remarkably, the latter is found to exceed its ideal gas limit deep in the pion condensed phase, the first account of the violation of this limit in first principles QCD. Finally, we also compute the phase diagram in the temperature -- isospin density plane for the first time. The data for all observables will be useful for the benchmarking of effective theories and low-energy models of QCD and are provided in ancillary files for simple reuse.

    ↳ hep-latastro-ph.HEhep-phnucl-thJHEP(2023)·101 citations
  6. 11

    Non-Gaussian fluctuation dynamics in relativistic fluids

    Xin An🇫🇮 · Gokce Basar🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸

    We consider non-equilibrium evolution of non-Gaussian fluctuations within relativistic hydrodynamics relevant for the QCD critical point search in heavy-ion collision experiments. We rely on the hierarchy of relaxation time scales, which emerges in the hydrodynamic regime near the critical point, to focus on the slowest mode such as the fluctuations of specific entropy, whose equilibrium magnitude, non-Gaussianity and typical relaxation time are increasing as the critical point is approached. We derive evolution equations for the non-Gaussian correlators of this diffusive mode in an arbitrary relativistic hydrodynamic flow. We compare with the simpler case of the stochastic diffusion on a static homogeneous background and identify terms which are specific to the case of the full hydrodynamics with pressure fluctuations and flow.

    ↳ hep-thcond-mat.stat-mechhep-phnucl-thPRC(2023)·29 citations
  7. 12

    General quantum algorithms for Hamiltonian simulation with applications to a non-Abelian lattice gauge theory

    Zohreh Davoudi🇺🇸 · Alexander F. Shaw🇺🇸 · Jesse R. Stryker🇺🇸

    With a focus on universal quantum computing for quantum simulation, and through the example of lattice gauge theories, we introduce rather general quantum algorithms that can efficiently simulate certain classes of interactions consisting of correlated changes in multiple (bosonic and fermionic) quantum numbers with non-trivial functional coefficients. In particular, we analyze diagonalization of Hamiltonian terms using a singular-value decomposition technique, and discuss how the achieved diagonal unitaries in the digitized time-evolution operator can be implemented. The lattice gauge theory studied is the SU(2) gauge theory in 1+1 dimensions coupled to one flavor of staggered fermions, for which a complete quantum-resource analysis within different computational models is presented. The algorithms are shown to be applicable to higher-dimensional theories as well as to other Abelian and non-Abelian gauge theories. The example chosen further demonstrates the importance of adopting efficient theoretical formulations: it is shown that an explicitly gauge-invariant formulation using loop, string, and hadron degrees of freedom simplifies the algorithms and lowers the cost compared with the standard formulations based on angular-momentum as well as the Schwinger-boson degrees of freedom. The loop-string-hadron formulation further retains the non-Abelian gauge symmetry despite the inexactness of the digitized simulation, without the need for costly controlled operations. Such theoretical and algorithmic considerations are likely to be essential in quantumly simulating other complex theories of relevance to nature.

    ↳ hep-lathep-phnucl-thquant-phQuantum(2023)·89 citations

Affiliations

first authorsco-authorsvia INSPIRE