[Paper Review] R-parity violation in split supersymmetry and neutralino dark matter: to be or not to be

Sudhir Kumar Gupta, Partha Konar+1 more|arXiv (Cornell University)|Aug 26, 2004

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper investigates R-parity violating split supersymmetry, showing that the lightest neutralino can remain cosmologically stable and viable as a dark matter candidate despite high squark/slepton masses. It identifies two decay scenarios—invisible decay or displaced vertices—and demonstrates that baryon and lepton number violation constraints are significantly relaxed in this framework.

ABSTRACT

In the recently proposed `split supersymmetry' scenario, the squark and slepton masses are allowed to be at a high scale while the gauginos and Higgsinos are within a TeV. We show that in a theory with broken R-parity, the parameter space of such a scenario allows a situation where the lightest neutralino is still stable on the cosmological scale and can be a dark matter candidate. We also separate the cases where (a) it may be invisible but not a dark matter candidate, or (b) it may decay showing a displaced vertex. It is also emphasized how the constraint on the simultaneous violation of baryon and lepton numbers gets relaxed in this scenario.

Motivation & Objective

• To examine whether the lightest neutralino can remain a stable dark matter candidate in split supersymmetry with broken R-parity.
• To classify scenarios where the neutralino decays invisibly or produces a displaced vertex.
• To assess how R-parity violation affects constraints on simultaneous baryon and lepton number violation in the split supersymmetry framework.

Proposed method

• Analyzing the neutralino mass spectrum and R-parity violating couplings in a split supersymmetry model with high squark/slepton masses.
• Evaluating the decay width and lifetime of the lightest neutralino to determine if it decays within the detector or remains stable.
• Using effective field theory techniques to model R-parity violating interactions and their phenomenological consequences.
• Applying cosmological and collider constraints to distinguish between stable, invisible, and displaced decay scenarios.
• Comparing the allowed parameter space for R-parity violating couplings under the split supersymmetry framework.

Experimental results

Research questions

• RQ1 Can the lightest neutralino remain stable on cosmological timescales in R-parity violating split supersymmetry?
• RQ2 Under what conditions does the neutralino decay with a displaced vertex rather than being invisible?
• RQ3 How does the split supersymmetry framework relax the constraints on simultaneous baryon and lepton number violation?
• RQ4 What are the phenomenological signatures of R-parity violating neutralino decays in this scenario?
• RQ5 How do the masses of squarks and sleptons influence the viability of the neutralino as a dark matter candidate?

Key findings

• The lightest neutralino can remain stable on cosmological timescales and thus serve as a viable dark matter candidate even with R-parity violation.
• Two distinct decay scenarios emerge: the neutralino may decay invisibly or produce a displaced vertex, depending on the R-parity violating coupling strengths.
• The constraint from simultaneous baryon and lepton number violation is significantly relaxed in the split supersymmetry framework.
• The model allows for a stable neutralino dark matter candidate despite high squark and slepton masses, preserving the naturalness of the TeV-scale gaugino and Higgsino sector.
• The phenomenology of R-parity violating decays is sensitive to the hierarchy between gaugino and Higgsino masses and the structure of the R-parity violating couplings.