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Large-scale Evolution of Seconds-long Relativistic Jets from Black Hole–Neutron Star Mergers
We present the first numerical simulations that track the evolution of a black hole–neutron star (BH–NS) merger from premerger to r ≳ 10 11 cm. The disk that forms after a merger of mass ratio q = 2 ejects massive disk winds (3–5 × 10 –2 M ⊙ ). We introduce various postmerger magnetic configurations and find that initial poloidal fields lead to jet launching shortly after the merger. The jet maintains a constant power due to the constancy of the large-scale BH magnetic flux until the disk becomes magnetically arrested (MAD), where the jet power falls off as L j ~ t –2 . All jets inevitably exhibit either excessive luminosity due to rapid MAD activation when the accretion rate is high or excessive duration due to delayed MAD activation compared to typical short gamma-ray bursts (sGRBs). This provides a natural explanation for long sGRBs such as GRB 211211A but also raises a fundamental challenge to our understanding of jet formation in binary mergers. One possible implication is the necessity of higher binary mass ratios or moderate BH spins to launch typical sGRB jets. For postmerger disks with a toroidal magnetic field, dynamo processes delay jet launching such that the jets break out of the disk winds after several seconds. We show for the first time that sGRB jets with initial magnetization σ0 > 100 retain significant magnetization (σ $\gg$ 1) at r > 10 10 cm, emphasizing the importance of magnetic processes in the prompt emission. The jet–wind interaction leads to a power-law angular energy distribution by inflating an energetic cocoon whose emission is studied in a companion paper.
Integrating out beyond tree level and relativistic superfluids
We revisit certain subtleties of renormalization that arise when one derives a low-energy effective action by integrating out the heavy fields of a more complete theory. Usually these subtleties are circumvented by matching some physical observables, such as scattering amplitudes, but a more involved procedure is required if one is interested in deriving the effective theory to all orders in the light fields (but still to fixed order in the derivative expansion). As a concrete example, we study the U(1) Goldstone low-energy effective theory that describes the spontaneously broken phase of a $\phi$ 4 theory for a complex scalar. Working to lowest order in the derivative expansion, but to all orders in the Goldstones, we integrate out the radial mode at one loop and express the low-energy effective action in terms of the renormalized couplings of the UV completion. This yields the one-loop equation of state for the superfluid phase of (complex) $\phi$ 4 . We perform the same analysis for a renormalizable scalar SO(N) theory at finite chemical potential, integrating out the gapped Goldstones as well, and confirm that the effective theory for the gapless Goldstone exhibits no obvious sign of the original SO(N) symmetry.
Geometrical scaling of direct photons in relativistic heavy ion and D+Au collisions
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Initial transverse-momentum broadening of Breit-Wheeler process in relativistic heavy-ion collisions
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Probing QCD critical fluctuations from the yield ratio of strange hadrons in relativistic heavy-ion collisions
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Hybrid Color Glass Condensate and hydrodynamic description of the Relativistic Heavy Ion Collider small system scan
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ν ν ¯ -Pair synchrotron emission in neutron-star matter based on a relativistic quantum approach
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Flavor hierarchy of jet quenching in relativistic heavy-ion collisions
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Charmed hadron chemistry in relativistic heavy-ion collisions
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Feeddown contributions from unstable nuclei in relativistic heavy-ion collisions
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Relativistic capture of dark matter by electrons in neutron stars
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Flavour and energy dependence of chemical freeze-out temperatures in relativistic heavy ion collisions from RHIC-BES to LHC energies
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Determine the neutron skin type by relativistic isobaric collisions
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Revisit the chiral magnetic effect expectation in isobaric collisions at the relativistic heavy ion collider
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Magneto-rotational dissociation of heavy hadrons in relativistic heavy-ion collisions
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Towards solving the puzzle of high temperature light (anti)-nuclei production in ultra-relativistic heavy ion collisions
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