Associated charged Higgs boson and squark production in the NUHM model

Conventional searches for the charged Higgs boson using its production in association with Standard Model (SM) quarks is notoriously weak in the mid-tanB range. Hoping to find an alternate channel to fill this gap, the production of the charged Higgs boson in association with supersymmetric squarks is studied. Using Monte Carlo generators the production at the LHC is simulated within the non universal Higgs mass model (NUHM). If the six parameters of the model (m0, m1/2, A0, tanB, u, mA) induce small masses of the stop, sbottom and charged Higgs, the production cross section can be of the order pb. Through scans of the input parameter the cross section is maximized, with the requirement that the stop decays directly to a neutralino – simplifying detection, in the point (m0, m1/2, A0, tanB, u, mA) = (190, 187, -1147, 179, 745, 13.2) where the cross section is 559 fb.The production is compared to the irreducible backgrounds stop, stop, t, tbar and t, tbar + 2 jets. The former poses no severe constraints and can be easily removed using appropriate cuts. The latter, SM background, has a cross section almost 1000 times larger and strong cuts must be imposed to suppress it. Neglecting hadronization and systematic effects, we show that a 5 sigma discovery is possible at 133 fb-1. In this range, mH+ = 194 GeV and tanB = 13.2, other channels have little or no prospects…


2 Introduction
2.1 The Standard model
2.1.1 Gauge invariance
2.1.2 The massive bosons
2.1.3 Strong interaction
2.1.4 Problems with the Standard Model
2.2 Supersymmetry
2.2.1 Why supersymmetry
2.2.2 The Wess-Zumino model
2.2.3 Soft symmetry breaking
2.2.4 Higgs sector and the NUHM
2.2.5 Particle content of the MSSM and NUHM
2.3 Project outline and motivation
3 Simulation tools
3.1 Spectrum calculators
3.1.1 SoftSUSY
3.1.2 Susyhit
3.2 Monte Carlo generators
3.2.1 MadGraph/MadEvent
3.2.2 Pythia
3.3 ROOT
4 Analysis
4.1 Initial scans over parameter space
4.1.1 H-t1-b1 coupling and squark masses
4.1.2 Cross section
4.1.3 Decays and detection
4.2 Signal and background
4.2.1 MSSM background
4.2.2 SM background
4.3 Comparison with other channels
5 Conclusions, Outlook
6 Acknowledgments

Author: Lund, Gustav

Source: Uppsala University Library

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