Abstract

A search is presented for massive long-lived particles, in the 20–60 {mathrm {Ge V!/}c^2} mass range with lifetimes between 5 and 100 mathrm{ps}. The dataset used corresponds to 0.62 text{ fb }^{-1} of proton-proton collision data collected by the LHCb detector at sqrt{s} =7mathrm {,Te V} . The particles are assumed to be pair-produced by the decay of a Higgs-like boson with mass between 80 and 140 {mathrm {Ge V!/}c^2}. No excess above the background expectation is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime and of the Higgs-like boson mass.

Highlights

  • The standard model of particle physics (SM) has shown great success in describing physics processes at very short distances

  • Supersymmetry (SUSY), in which the strong and electroweak forces are unified at a renormalisation scale near the Planck scale, provides a possible solution for the hierarchy problem; the minimal supersymmetric standard model (MSSM) is the simplest, phenomenologically viable realisation of SUSY [1,2]

  • The present study focuses on a subset of models featuring massive long-lived particles (LLP) with a measurable flight distance

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Summary

Introduction

The standard model of particle physics (SM) has shown great success in describing physics processes at very short distances. Supersymmetry (SUSY), in which the strong and electroweak forces are unified at a renormalisation scale near the Planck scale, provides a possible solution for the hierarchy problem; the minimal supersymmetric standard model (MSSM) is the simplest, phenomenologically viable realisation of SUSY [1,2]. The present study focuses on a subset of models featuring massive long-lived particles (LLP) with a measurable flight distance. We concentrate on scenarios in which the LLP decays hadronically in the LHCb vertex detector, travelling distances which can be larger than those of typical b hadrons. The explored LLP lifetime range of 5–100 ps is higher than the typical b hadron lifetime, and corresponds to an average flight distance of up to 30 cm, which is inside the LHCb vertex detector region. The LLP mass range considered is between 20 and 60 GeV/c2

Detector description
Event generation and detector simulation
Background
Determination of the di-LLP signal
Detection efficiency and systematic uncertainties
Results
Conclusion
A Fully simulated signal datasets
C Cross-section upper limits tables
Full Text
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