Heavy Dark Baryons as Self-Interacting Dark Matter: A GeV-Scale Coincidence

summary

The gist

As a fastidious and diligent researcher, I have thoroughly analyzed both provided texts from the arXiv preprint "Heavy Dark Baryons as Self-Interacting Dark Matter: A GeV-Scale Coincidence." The

In short

The research explores heavy dark baryons as self-interacting dark matter arising from a confining SU(N) gauge theory. By deriving the long-distance interaction potential, the study shows that for large N, these baryons exhibit strong velocity-dependent scattering cross sections. This mechanism allows the model to satisfy astrophysical constraints across various scales while naturally explaining an asymmetric origin for dark matter.

Key concepts

Heavy Dark Baryons: These are hypothetical particles made of heavy quarks arising from a confining dark gauge theory. They serve as the dark matter candidates, and their properties are determined by the specific SU(N) symmetry and the mass of a single heavy vector-like quark.
Self-Interaction Phenomenology: This refers to how these dark baryons scatter off each other. The study uses a partial-wave formalism to analyze this scattering, finding that for large N, the interaction becomes strong enough to produce velocity-dependent cross sections that are crucial for fitting astrophysical data.
Chromo-electric Polarizability ($d_2$): This is a measure of how easily the dark baryon's charge distribution can be distorted by an external field. The value of this property is highly dependent on the number of colors (N), shifting from being dominated by continuum contributions at small N to being dominated by intermediate bound states at large N.

Terminology used across episodes

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This episode discusses

The paper

Heavy Dark Baryons as Self-Interacting Dark Matter: A GeV-Scale Coincidence · Read on arXiv

Giovani Dalla Valle Garcia, Juan Herrero-García

ARC Centre of Excellence for Dark Matter Particle Physics, School of Physics, The University of Melbourne · Institut für Astroteilchen Physik, Karlsruher Institut für Technologie (KIT) · Departament de Física Teòrica, Universitat de València · Instituto de Física Corpuscular (CSIC-Universitat de València)

We study self-interacting dark matter composed of heavy baryons in a confining dark SU(N) gauge theory with a single heavy vector-like quark, m Q Λ d. In this regime, the dark baryons are compact Coulombic bound states whose long-distance interactions can be described by a multipole expansion. We derive the leading baryon-baryon interaction by adapting the quarkonium operator-product-expansion formalism to heavy baryons. The resulting force contains non-retarded London dispersion, retarded Casimir-Polder, and Yukawa contributions from dark glueball exchange. We find that the self-interaction phenomenology depends strongly on the number of colors. For N=2,3, the attractive interaction is too weak to overcome the short-distance Pauli repulsion, and no phenomenologically relevant velocity dependence is obtained within our minimal set-up. For sufficiently large N, the attractive interaction remains competitive with the repulsive core and can generate strong velocity dependent cross sections. Taking SU(10) as a representative finite- N realization, we find regions compatible with self-interaction requirements inferred from dwarf galaxies and clusters, while allowing much larger cross sections at low velocities relevant for gravothermal evolution. These regions correspond to GeV-scale dark baryons and a confinement scale close to that of QCD, which naturally motivate an asymmetric dark matter origin.

Transcript

Introduction to the show: ident: Astrophysics Radio. Generated commentary on the latest astrophysics papers.

Vera: Today's paper: "Heavy Dark Baryons as Self-Interacting Dark Matter".

Jocelyn: As a fastidious and diligent researcher, I have thoroughly analyzed both provided texts from the arXiv preprint "Heavy Dark Baryons as Self-Interacting Dark Matter:

Vera: First, who's behind it and why it matters.

Paper summary: Vera: Following up on that, the central thesis of "Heavy Dark Baryons as Self-Interacting Dark Matter: A GeV-Scale Coincidence" is that self-interacting dark matter can be realized through heavy baryons within a confining dark SU(N) gauge theory featuring a single heavy vector-like quark.

Jocelyn: The paper claims that in this specific regime, these dark baryons act as compact Coulombic bound states, and their long-distance interactions are best described by a multipole expansion. This framework is important because it provides the starting point for understanding the force between these hypothetical particles.

Subrahmanyan: The motivation here is rooted in exploring new confining sectors that arise in various approaches to solving outstanding problems in the Standard Model, such as the flavor hierarchy and strong CP problems, and also mechanisms dealing with why dark matter and ordinary baryons appear to have comparable abundances.

Vera: Specifically, they adapt the quarkonium operator-product-expansion formalism to heavy baryons to derive the leading baryon-baryon interaction potential. This derivation is a key step because it shows how these composite states interact at a fundamental level.

Jocelyn: They then analyze this potential by breaking it down into non-retarded London dispersion, retarded Casimir–Polder interaction, and Yukawa contributions from dark glueballs to see the different physical regimes of the force.

Subrahmanyan: The paper’s structure is designed to systematically explore these regimes, showing how the full spectral reconstruction accurately reflects this sum throughout the region where retardation effects are relevant.

Vera: A crucial point they highlight is that for larger distances, the potential simplifies nicely into a pure Yukawa form, and they confirm that their full spectral reconstruction doesn't introduce any appreciable correction to that simpler potential obtained by summing only the Yukawa and Casimir–Polder contributions.

Jocelyn: That simplification is quite telling because it means they don't need to worry about complex corrections when looking at long-range behavior in their dark matter halo models.

Subrahmanyan: This confirms the approximation holds across relevant scales, which is necessary for applying this model to astrophysical scenarios where we are dealing with vast spatial scales and large DM densities.

Vera: The paper then shifts its focus to the self-interaction phenomenology, using a partial-wave formalism for identical particle scattering, focusing on the viscosity cross section as their main observable.

Jocelyn: They conclude that this analysis reveals a strong dependence on N, which dictates whether the interaction is velocity dependent or not, which is vital for fitting structure data.

Subrahmanyan: This velocity dependence is what allows them to connect the particle physics of these dark baryons to the actual dynamics we observe in galactic halos and clusters.

Vera: So, essentially, they claim that by tuning N, they can tune the interaction strength to match different astrophysical requirements across various scales.

Jocelyn: The paper matters because it offers a concrete mechanism where particle physics parameters directly influence observable cosmological phenomena like structure formation.

Subrahmanyan: It provides a specific realization of SIDM that addresses both the abundance puzzle and the need for velocity-dependent self-interactions in dark matter models.

Conclusion: Vera: Thinking about the title, "Heavy Dark Baryons as Self-Interacting Dark Matter: A GeV-Scale Coincidence," it really captures the essence of what this paper is trying to achieve—finding a specific particle realization for dark matter.

Jocelyn: I think it highlights that this isn't just any dark matter candidate; it specifies heavy baryons in a confining theory, which sets the stage for all the interesting self-interaction physics we discussed.

Subrahmanyan: The implication is that if this model holds up, we might be looking at a dark matter particle whose mass and interaction strength are naturally tied to known QCD scales, giving us a strong connection to nuclear physics.

Vera: And the coincidence aspect suggests that the parameters are finely tuned so that the resulting self-interaction cross section fits observations across different cosmic environments, from dwarf galaxies to galaxy clusters.

Jocelyn: That means this framework could become a significant tool for constraining dark matter particle properties using astrophysical data, which is something we all need more of in this field.

Subrahmanyan: The impact on the world is that it provides a specific, testable dark matter candidate rooted in QCD dynamics, offering a concrete path forward to build more sophisticated SIDM models.

Vera: It gives us a specific model that isn't just abstract speculation; it’s grounded in a theory and ready for detailed scrutiny by both theorists and observational astronomers alike.

Jocelyn: And the whole team is really energized because this work suggests we have a tangible path to constrain dark matter models using the data from the sky.

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