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Bulk viscosity of strongly interacting matter in the relaxation time approximation
Here, we show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the β λ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ς/τ R for gases obeying Bose-Einstein statistics.
Dark matter relic density in strongly interacting dark sectors with light vector mesons
Stable dark matter particles may arise as pseudo-Goldstone bosons from the confinement of dark quarks interacting via a non-Abelian gauge force. Their relic abundance is determined not by annihilations into visible particles but by dark pion number-changing processes within the dark sector, such as 3 π D → 2 π D . However, if the dark vector mesons ρ D are light enough for 3 π D → π D ρ D annihilations to be kinematically allowed, this process dominates and significantly delays freeze-out. As a result, the preferred dark matter mass scale increases and bounds from the Bullet Cluster can be evaded. Published by the American Physical Society 2024
Strongly interacting dark matter: Self-interactions and keV lines
Herein, we consider a simple supersymmetric hidden sector: pure SU ( N ) gauge theory. Dark matter is made up of hidden glueballinos with mass m X and hidden glueballs with mass near the confinement scale Λ . For m X ~ 1 TeV and Λ ~ 100 MeV , the glueballinos freeze out with the correct relic density and self-interact through glueball exchange to resolve small-scale structure puzzles. An immediate consequence is that the glueballino spectrum has a hyperfine splitting of order Λ 2 / m X ~ 10 keV . We illustrate that the radiative decays of the excited state can explain the observed 3.5 keV x-ray line signal from clusters of galaxies, Andromeda, and the Milky Way.
Cosmology and accelerator tests of strongly interacting dark matter
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Robust constraints and novel gamma-ray signatures of dark matter that interacts strongly with nucleons
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Strongly interacting massive particles through the axion portal
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Twin Higgs model with strongly interacting massive particle dark matter
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Universal Slow Growth of Entanglement in Interacting Strongly Disordered Systems
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Mechanism for Thermal Relic Dark Matter of Strongly Interacting Massive Particles
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Model for Thermal Relic Dark Matter of Strongly Interacting Massive Particles
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Coulomb bound states of strongly interacting photons
We show that two photons coupled to Rydberg states via electromagnetically induced transparency (EIT) can interact via an effective Coulomb potential. The interaction then gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb problem, thus obtaining a photonic analogue of the hydrogen atom. These states propagate with a negative group velocity in the medium, which allows for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms. As a result, we verify the metastability and backward propagation of these Coulomb bound states with exact numerical simulations.
Depolarization Dynamics in a Strongly Interacting Solid-State Spin Ensemble
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Symmetric Nuclear Matter from the Strong Interaction
We study the equation of state of symmetric nuclear matter at zero temperature over a wide range of densities using two complementary theoretical approaches. At low densities, up to twice nuclear saturation density, we compute the energy per particle based on modern nucleon-nucleon and three-nucleon interactions derived within chiral effective field theory. For higher densities, we derive for the first time constraints in a Fierz-complete setting directly based on quantum chromodynamics using functional renormalization group techniques. Here, we find remarkable consistency of the results obtained from both approaches as they come together in density and the natural emergence of a maximum in the speed of sound 𝑐𝑆 at supranuclear densities. The presence of this maximum appears tightly connected to the formation of a diquark gap. Notably, this maximum is observed to exceed the asymptotic value 𝑐$^{2}_{𝑆}$ =1/3 while its exact position in terms of the density cannot yet be determined conclusively.