Analysis of p-Wave Sommerfeld Resonance Behavior in Finite-Size Dark Matter

summary

The gist

The gist: The analysis investigates how finite-size effects modify p-wave Sommerfeld resonance behavior for dark matter, finding that these effects weaken resonances compared to point-like dark

In short

The study investigates how finite size affects p-wave Sommerfeld resonances in dark matter, comparing it to point-like models. It finds that while finite size weakens these resonances, their velocity dependence remains similar to point particles. The analysis also shows that for nugget dark matter with a defined structure, the behavior mirrors the point-like case.

Key concepts

Sommerfeld enhancement: This is a mechanism where long-range forces between dark matter particles can enhance their annihilation cross section, especially at low relative velocities. It's used to explain how dark matter might satisfy different requirements for cosmic evolution.
p-wave resonance: This refers to a specific type of resonance in the annihilation process involving p-wave interactions. The paper examines how the presence of finite size alters these resonances compared to idealized point particles.
Finite-size dark matter: This considers dark matter as having a physical size, like a proton or neutron, instead of being an infinitely small point particle. This introduces new parameters and can change how interactions are calculated.
Nugget dark matter: This is a specific type of finite-size dark matter composed of only a few constituents. The analysis shows that when the internal structure is specified, its resonance behavior becomes very similar to that of a point particle.

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This episode discusses

The paper

Analysis of p-Wave Sommerfeld Resonance Behavior in Finite-Size Dark Matter · Read on arXiv

Wu-Long Xua, Jin Min Yangb, Rui Zhud

School of Integrated Circuits, Chengdu Technological University · Center for Theoretical Physics, Henan Normal University · Institute of Theoretical Physics, Chinese Academy of Sciences · State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute, Shanghai Jiao Tong University · Key Laboratory for Particle Astrophysics and Cosmology (MOE) & Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai Jiao Tong University

Different stages of cosmic evolution impose different requirements on the dark matter annihilation cross section. Sommerfeld enhancement provides a possible way to accommodate them. However, in the point-like dark matter scenario, satisfying these requirements with either s-wave or p-wave Sommerfeld enhancement can strongly constrain the dark matter and mediator masses and their coupling. A finite dark matter size introduces an additional parameter and may relax these constraints. Motivated by this possibility, in this work we study the p-wave Sommerfeld resonances of finite-size dark matter (like proton or neutron) without specifying its internal structure. We find that the p-wave contribution can exceed the s-wave contribution. Nevertheless, the finite-size p-wave resonances are weaker than those in the point-like case. Despite this suppression, their velocity dependence remains similar to that of point-like dark matter. We then extend our analysis to nugget dark matter composed of a small number of constituents. In this case, the p-wave Sommerfeld enhancement exhibits behavior similar to that of point-like dark matter.

Transcript

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

Vera: I'm Vera, and with me are Jocelyn and Subrahmanyan, guest researcher.

Jocelyn: Today's paper: "Analysis of p-Wave Sommerfeld Resonance Behavior in Finite-Size Dark Matter".

Vera: The gist: The analysis investigates how finite-size effects modify p-wave Sommerfeld resonance behavior for dark matter,

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

Paper summary: Vera: To summarize what this paper, "Analysis of p-Wave Sommerfeld Resonance Behavior in Finite-Size Dark Matter," is doing, it's looking at how finite size modifies the p-wave Sommerfeld resonance. The authors are testing this against the background that different cosmic epochs need different annihilation cross sections.

Jocelyn: They claim that while point-like dark matter has strong constraints on masses and couplings for s-wave or p-wave enhancement, introducing a finite size gives us an extra parameter that might relax those tight constraints.

Subrahmanyan: The core idea is looking at the p-wave Sommerfeld resonances of finite-size dark matter without picking a specific internal structure initially. They find that the p-wave contribution can be larger than the s-wave contribution in this scenario, even if it's suppressed compared to point particles.

Vera: And they also look at nugget dark matter composed of a small number of constituents, and they show that when you specify the internal structure, like for a nugget, the p-wave enhancement acts similarly to point-like dark matter.

Jocelyn: It’s interesting because it shows that for these finite objects without specified structure, you get blurred internal structures but relatively clear resonance boundaries.

Subrahmanyan: So what this means is that even with these size effects, the velocity dependence of the resonances stays similar to point-like dark matter. This suggests that certain dynamical requirements are still present across different scenarios.

Vera: Exactly. And they conclude that these findings have implications for reconciling the different annihilation cross sections needed at various stages of cosmic evolution.

Jocelyn: So we've seen how the paper sets up the problem with finite size, what they find about the p-wave versus s-wave contributions, and how nugget dark matter behaves when you define its structure.

Conclusion: Vera: So looking at "Analysis of p-Wave Sommerfeld Resonance Behavior in Finite-Size Dark Matter," we see a study that uses finite size as a tool to loosen the grip on dark matter parameters compared to the point particle case.

Jocelyn: The authors are showing us that while these size effects can suppress the resonance magnitude, they don't change the velocity dependence much, which is important for how we think about cosmic evolution across different times.

Subrahmanyan: Ultimately, this work suggests that finite-size dark matter effects might be a viable way to accommodate the diverse annihilation cross sections required by different cosmic stages.

Vera: It gives us a path forward where we can still get meaningful constraints on mass and interaction strength without needing a full microscopic model for the dark matter's internal structure.

Jocelyn: So, in simple terms, it’s about using finite size to find a better fit for the annihilation cross sections needed at different times in cosmic history.

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