PaperPanorama

Nuclear Theory·nucl-th

Wednesday·September 8, 2021

6 papers2 primary·4 cross-listed

  1. 03

    Dissipative Magnetohydrodynamics for Non-Resistive Relativistic Plasmas

    Elias R. Most🇺🇸 · Jorge Noronha🇺🇸

    Based on a 14-moment closure for non-resistive (general-) relativistic viscous plasmas, we describe a new numerical scheme that is able to handle all first-order dissipative effects (heat conduction, bulk and shear viscosities), as well the anisotropies induced by the presence of magnetic fields. The latter is parameterized in terms of a thermal gyrofrequency or, equivalently, a thermal Larmor radius and allows to correctly capture the thermal Hall effect. By solving an extended Israel-Stewart-like system for the dissipative quantities that enforces algebraic constraints via stiff-relaxation, we are able to cast all first-order dissipative terms in flux-divergence form. This allows us to apply traditional high-resolution shock capturing methods to the equations, making the system suitable for the numerical study of highly turbulent flows. We present several numerical tests to assess the robustness of our numerical scheme in flat spacetime. The 14-moment closure can seamlessly interpolate between the highly collisional limit found in neutron star mergers, and the highly anisotropic limit of relativistic Braginskii magnetohydrodynamics appropriate for weakly collisional plasmas in black-hole accretion problems. We believe that this new formulation and numerical scheme will be useful for a broad class of relativistic magnetized flows.

    astro-ph.HEgr-qcnucl-thphysics.comp-ph+1PRD(2021)·42 citations
  2. 04

    Holographic charm and bottom pentaquarks III: Excitations through photo-production of heavy mesons

    Yizhuang Liu🇵🇱 · Kiminad A. Mamo🇺🇸 · Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸

    We consider the photo-excitation of charm and bottom pentaquarks with the holographic assignments and , in the photo-production of heavy vector mesons such as charmonia and bottomonia near threshold. We use a Witten diagram to combine the s-channel photo-excitation of holographic pentaquarks with a massive t-channel graviton or tensor glueball exchange, to extract the scattering amplitude for heavy meson photo-production in the threshold region. The pentaquark signal is too weak to be detected at current electron facilities.

    hep-phhep-thnucl-exnucl-thPRD(2021)·10 citations
  3. 05

    SU(3) flavor symmetry considerations for the coupled channels system

    P. C. Bruns🇨🇿 · A. Cieplý🇨🇿

    We study the impact of SU(3) flavor symmetry breaking on the properties of dynamically generated states within an effective separable potential model describing the coupled channels system. The model is based on the chiral meson-baryon Lagrangian at next-to-leading order, and constitutes an improvement over a previous model developed by our group, with its applicability being extended to higher energies covering the resonance region. It is demonstrated that the ratios of channel couplings to the resonant states can vary dramatically when the flavor breaking is gradually switched off, tracing a path to the restored SU(3) symmetry. We conclude that the couplings determined from physical observables cannot be used to reliably relate a given resonance to a specific flavor multiplet.

    hep-phnucl-thNPA(2022)·20 citations
  4. 06

    Determination of and stripping excitation functions for O+Ce using a Recoil Mass Spectrometer

    Rohan Biswas · S. Nath · J. Gehlot · Gonika · Chandra Kumar · A. Parihari · N. Madhavan · A. Vinayak · Amritraj Mahato · Shoaib Noor · Phurba Sherpa · Kazuyuki Sekizawa

    We report the first direct measurement of differential transfer cross sections using a Recoil Mass Spectrometer. Absolute differential and -stripping cross sections at have been determined for the system O+Ce by detecting the heavier target-like ions at the focal plane of the Heavy Ion Reaction Analyzer. Focal plane spectra have been compared with the results of a semi-microscopic Monte-Carlo simulation to unambiguously identify the transfer channels. Transmission efficiency of the target-like ions through the spectrometer has also been estimated using the simulation. The methodology adopted in this work can be applied to other recoil separators. The measured excitation functions for the reactions and have been compared with coupled reaction channel calculations. An excellent matching between measurement and theory has been obtained. For -stripping, major contribution to the cross section has been found to be the transfer of a proton from to the excited state of , leaving behind in the ground state. Transfer of a cluster of two protons from to the excited state of , resulting in in the ground state, appears to be the most probable cause for -stripping. Measured transfer probabilities for and channels have been compared with Time-Dependent Hartree-Fock calculations. Proton stripping channels are found to be more favourable compared to neutron pick-up channels. However, the theory overpredicts measurement hinting at the need for extended approaches with explicit treatment of pairing correlations in the calculations.

    nucl-exnucl-thEPJA(2023)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE