Abstract
A search is performed for a pseudoscalar Higgs boson, A, decaying into a 125 GeV Higgs boson h and a Z boson. The h boson is specifically targeted in its decay into a pair of tau leptons, while the Z boson decays into a pair of electrons or muons. A data sample of proton-proton collisions collected by the CMS experiment at the LHC at sqrt{s} = 13 TeV is used, corresponding to an integrated luminosity of 35.9 fb−1. No excess above the standard model background expectations is observed in data. A model-independent upper limit is set on the product of the gluon fusion production cross section for the A boson and the branching fraction to Zh → ℓℓττ. The observed upper limit at 95% confidence level ranges from 27 to 5 fb for A boson masses from 220 to 400 GeV, respectively. The results are used to constrain the extended Higgs sector parameters for two benchmark scenarios of the minimal supersymmetric standard model.
Highlights
Background estimationThe irreducible backgrounds (ZZ → 4, ttZ, WWZ, WZZ, ZZZ) and the production of the 125 GeV Higgs boson via the processes predicted by the SM are estimated from simulation
Simulated signal events with a pseudoscalar Higgs boson A produced in gluon fusion, decaying into a 125 GeV Higgs boson and a Z boson and into two tau and two leptons are generated at leading order (LO) using MadGraph5 amc@nlo v2.4.2 [32]
To produce model-dependent interpretations of the results described in section 8, we utilize production cross section and branching fraction calculations for the pseudoscalar A in the M1h2,E5FT and hMSSM scenarios
Summary
The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Forward calorimeters extend the pseudorapidity (η) coverage provided by the barrel and endcap detectors. Events of interest are selected using a two-tiered trigger system [30]. The first level (L1), composed of custom hardware processors, uses information from the calorimeters and muon detectors to select events at a rate of around 100 kHz within a time interval of less than 4 μs. The second level, known as the high-level trigger (HLT), consists of a farm of processors running a version of the full event reconstruction software optimized for fast processing, and reduces the event rate to around 1 kHz before data storage. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kinematic variables, can be found in ref. [31]
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