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Nuclear Theory·nucl-th

Friday·April 8, 2022

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 03

    Long-term 3D-MHD Simulations of Black Hole Accretion Disks formed in Neutron Star Mergers

    Steven Fahlman · Rodrigo Fernández

    We examine the long-term evolution of accretion tori around black hole (BH) remnants of compact object mergers involving at least one neutron star, to better understand their contribution to kilonovae and the synthesis of r-process elements. To this end, we modify the unsplit magnetohydrodynamic (MHD) solver in FLASH4.5 to work in non-uniform three-dimensional spherical coordinates, enabling more efficient coverage of a large dynamic range in length scales while exploiting symmetries in the system. This modified code is used to perform BH accretion disk simulations that vary the initial magnetic field geometry and disk compactness, utilizing a physical equation of state, a neutrino leakage scheme for emission and absorption, and modeling the BH's gravity with a pseudo-Newtonian potential. Simulations run for long enough to achieve a radiatively-inefficient state in the disk. We find robust mass ejection with both poloidal and toroidal initial field geometries, and suppressed outflow at high disk compactness. With the included physics, we obtain bimodal velocity distributions that trace back to mass ejection by magnetic stresses at early times, and to thermal processes in the radiatively-inefficient state at late times. The electron fraction distribution of the disk outflow is broad in all models, and the ejecta geometry follows a characteristic hourglass shape. We test the effect of removing neutrino absorption or nuclear recombination with axisymmetric models, finding less mass ejection and more neutron-rich composition without neutrino absorption, and a subdominant contribution from nuclear recombination. Tests of the MHD and neutrino leakage implementations are included.

    ↳ astro-ph.HEastro-ph.SRgr-qcnucl-thMNRAS(2022)·36 citations
  2. 04

    Single Inclusive Jet Production in Collisions at NLO in the small- regime

    Hao-yu Liu🇨🇳 · Kexin Xie🇨🇳 · Zhongbo Kang🇺🇸 · Xiaohui Liu🇨🇳

    We present the first complete NLO prediction with full jet algorithm implementation for the single inclusive jet production in collisions within the CGC effective theory. Our prediction is fully differential over the final state physical kinematics, which allows the implementation of any IR safe observable including the jet clustering procedure. The NLO calculation is organized with the aid of the power counting proposed in [1] which gives rise to the novel soft contributions in the CGC factorization. We achieve the fully-differential calculation by constructing suitable subtraction terms to handle the singularities in the real corrections. The subtraction contributions can be exactly integrated analytically. We present the NLO cross section with the jets constructed using the anti- algorithm. The NLO calculation demonstrates explicitly the validity of the CGC factorization in jet production. Furthermore, as a byproduct of the subtraction method, we also derive the fully analytic cross section for the forward jet production in the small- limit. We show that in the small- approximation, the forward jet cross section can be factorized into a semi-hard cross section that produces a parton and the semi-inclusive jet functions. We argue that this feature holds for generic jet production and jet substructure observables in the CGC framework. Last, we show numerical analyses of the derived formula to validate our calculations. We justify when the small- approximation is appropriate. Like forward hadron production, the obtained NLO result also exhibits the negativity of the cross section in the large jet transverse regime, which signals the need for the threshold resummation. A sketch of the threshold resummation in the CGC framework is presented based on the multiple emission picture.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2022)·28 citations
  3. 05

    Universal Relations for Neutron Star F-Mode and G-Mode Oscillations

    Tianqi Zhao · James M. Lattimer

    Among the various oscillation modes of neutron stars, f- and g- modes are the most likely to be ultimately observed in binary neutron star mergers. The f-mode is known to correlate in normal neutron stars with their tidal deformability, moment of inertia and quadrupole moment. Using a piecewise polytropic parameterization scheme to model the uncertain hadronic high-density EOS and a constant sound-speed scheme to model pure quark matter, we refine this correlation and show that these universal relations also apply to both self-bound stars and hybrid stars containing phase transitions. We identify a novel 1-node branch of the f-mode that occurs in low-mass hybrid stars in a narrow mass range just beyond the critical mass necessary for a phase transition to appear. This 1-node branch shows the largest, but still small, deviations from the universal correlation we have found. The g-mode frequency only exists in matter with a non-barotropic equation of state involving temperature, chemical potential or composition, or a phase transition in barotropic matter. The g-mode therefore could serve as a probe for studying phase transitions in hybrid stars. In contrast with the f-mode, discontinuity g-mode frequencies depend strongly on properties of the transition (the density and the magnitude of the discontinuity) at the transition. Imposing causality and maximum mass constraints, the g-mode frequency in hybrid stars is found to have an upper bound of about 1.25 kHz. However, if the sound speed c_s in the inner core at densities above the phase transition density is restricted to c_s^2 < c^2/3, the g-mode frequencies can only reach about 0.8 kHz, which are significantly lower than f-mode frequencies, 1.3-2.8 kHz. Also, g-mode gravitational wave damping times are extremely long, >10^4 s (10^2 s) in the inner core with c_s^2< c^{2/3} (c^2), in comparison with the f-mode damping time, 0.1-1 s.

    ↳ astro-ph.HEastro-ph.SRgr-qcnucl-thPRD(2022)·89 citations
  4. 06

    Quantum Simulation for High Energy Physics

    Christian W. Bauer🇺🇸 · Zohreh Davoudi🇺🇸 · A. Baha Balantekin🇺🇸 · Tanmoy Bhattacharya🇺🇸 · Marcela Carena🇺🇸 · Wibe A. de Jong🇺🇸 · Patrick Draper🇺🇸 · Aida El-Khadra🇺🇸 · Nate Gemelke🇺🇸 · Masanori Hanada🇬🇧 · Dmitri Kharzeev🇺🇸 · Henry Lamm🇺🇸 and 19 other authors

    It is for the first time that Quantum Simulation for High Energy Physics (HEP) is studied in the U.S. decadal particle-physics community planning, and in fact until recently, this was not considered a mainstream topic in the community. This fact speaks of a remarkable rate of growth of this subfield over the past few years, stimulated by the impressive advancements in Quantum Information Sciences (QIS) and associated technologies over the past decade, and the significant investment in this area by the government and private sectors in the U.S. and other countries. High-energy physicists have quickly identified problems of importance to our understanding of nature at the most fundamental level, from tiniest distances to cosmological extents, that are intractable with classical computers but may benefit from quantum advantage. They have initiated, and continue to carry out, a vigorous program in theory, algorithm, and hardware co-design for simulations of relevance to the HEP mission. This community whitepaper is an attempt to bring this exciting and yet challenging area of research to the spotlight, and to elaborate on what the promises, requirements, challenges, and potential solutions are over the next decade and beyond.

    ↳ quant-phhep-lathep-phhep-th+1PRX Quantum(2023)·561 citations

Affiliations

first authorsco-authorsvia INSPIRE