Search for top squarks at Tevatron inspired by dark matter and electroweak baryogenesis

Nabanita Bhattacharyya,Amitava Datta,Manas Maity

doi:10.1016/j.physletb.2008.10.015

Nabanita Bhattacharyya, Amitava Datta + Show 1 more

Open Access

https://doi.org/10.1016/j.physletb.2008.10.015

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Abstract

The search for the top squark (t˜1) within the kinematic reach of Tevatron Run II is of great contemporary interest. Such a t˜1 can explain the baryon asymmetry of the universe provided 120 GeV⩽mt˜1⩽mt. Moreover if Δm≡mt˜1−mχ˜10 is small, where χ˜10 is the lightest supersymmetric particle (LSP), the dark matter relic density as obtained from the WMAP data may be explained via t˜1-LSP coannihilation. In this scenario the decay t˜1→cχ˜10 is likely to occur with 100% branching ratio but for small Δm the conventional di-jet+E̸T signal becomes unobservable. We propose a new search strategy based on the di-jet+E̸T signature accompanied by an isolated cluster of energy which arises from a decaying heavy particle with characteristic decay length. Our preliminary simulations with Pythia indicate that for 100 GeV⩽mt˜1⩽130 GeV this signal may be observable while somewhat lager mt˜1 may still provide hints of new physics.

Highlights

In the Minimal Supersymmetric Standard Model (MSSM) [1] there are two scalar superpartners tL and tR, of the top quark which are the weak eigenstates
Due to mixing effects in the top squark mass matrix in the weak basis driven by the top quark mass there may be a significant mass difference between t1 and t2
The former could very well be the next-to-lightest supersymmetric particle (NLSP), the lightest neutralino (χ01) being the lightest supersymmetric particle (LSP) by the standard assumption in R-parity conserving MSSM. This happens in a wide region of the MSSM parameter space

Summary

Introduction

In the Minimal Supersymmetric Standard Model (MSSM) [1] there are two scalar superpartners tL and tR, of the top quark which are the weak eigenstates. As a result the efficiency of the kinematical cuts for suppressing the background as well as that of c-jet tagging decreases. Even in more restricted versions of the MSSM like the minimal supergravity model(mSUGRA) [14] one finds a narrow region of the parameter space where t1 - LSP coannihilation is an important relic density producing mechanism[15].

Results

Conclusion