Abstract
We investigate the potential for enhancing search sensitivity for signals having charm quarks in the final state, using the sizable bottom-mistagging rate for charm quarks at the LHC. Provided that the relevant background processes contain light quarks instead of charm quarks, the application of b-tagging on charm quark-initiated jets enables us to reject more background events than signal ones due to the relatively small mistagging rate for light quarks. The basic idea is tested with two rare top decay processes: i) t -> c h -> c b bbar and ii) t -> b H+ -> b bbar c where h and H+ denote the Standard Model-like higgs boson and a charged higgs boson, respectively. The major background source is a hadronic top quark decay such as t -> b W+ -> b sbar c. We test our method with Monte Carlo simulation at the LHC 14TeV, and find that the signal-over-background ratio can be increased by a factor of O(6-7) with a suitably designed (heavy) flavor tagging algorithm and scheme.
Highlights
The discovery of the Higgs particle at the Large Hadron Collider (LHC) [1, 2] reaffirms that the Standard Model (SM) is a successful description of fundamental particles and their interactions in nature
As mentioned at the beginning, the LHC is capable of copiously producing top quark pairs, which makes the search channels discussed here become systematicsdominated
Considering the typical κ of O(3%) for the ttchannel, we find that the second term in the denominator becomes larger than the first one once B is greater than ∼ 1100
Summary
The discovery of the Higgs particle at the Large Hadron Collider (LHC) [1, 2] reaffirms that the Standard Model (SM) is a successful description of fundamental particles and their interactions in nature. Existing experimental searches of t → bH+ → bsc done by the CDF [16] and ATLAS [17] collaborations could be applied to the decay of H+ → cb [12], an enhanced branching ratio motivates more dedicated searches to discover a new phenomenon or directly constrain the parameter space in the relevant physics models. It is noteworthy that this event selection enables us to have the hadronic top quark decaying into bsc (i.e., t → bW + → bsc) as a main background source because the b-mistagging rate for charm quarks is rather sizable. We take it as the major background unless specified otherwise.
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