Abstract
A search is presented for massive narrow resonances decaying either into two Higgs bosons, or into a Higgs boson and a W or Z boson. The decay channels considered are mathrm{H}mathrm{H}to mathrm{b}overline{mathrm{b}}{tau}^{+}{tau}^{-} and mathrm{V}mathrm{H}to mathrm{q}overline{mathrm{q}}{tau}^{+}{tau}^{-} , where H denotes the Higgs boson, and V denotes the W or Z boson. This analysis is based on a data sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV by the CMS Collaboration, corresponding to an integrated luminosity of 35.9 fb−1. For the TeV-scale mass resonances considered, substructure techniques provide ways to differentiate among the hadronization products from vector boson decays to quarks, Higgs boson decays to bottom quarks, and quark- or gluon-induced jets. Reconstruction techniques are used that have been specifically optimized to select events in which the tau lepton pair is highly boosted. The observed data are consistent with standard model expectations and upper limits are set at 95% confidence level on the product of cross section and branching fraction for resonance masses between 0.9 and 4.0 TeV. Exclusion limits are set in the context of bulk radion and graviton models:spin-0 radion resonances are excluded below a mass of 2.7 TeV at 95% confidence level. In the spin-1 heavy vector triplet framework, mass-degenerate W′ and Z′ resonances with dominant couplings to the standard model gauge bosons are excluded below a mass of 2.8 TeV at 95% confidence level. These are the first limits for massive resonances at the TeV scale with these decay channels at sqrt{s}=13 TeV.
Highlights
Background estimationThe main sources of background originate from top quark pair production and from the production of a vector boson in association with jets (Z+jets and W+jets), while minor contributions arise from single top quark, diboson, and multijet production
The shape of the distribution of the top quark pair and single top quark background is determined from simulation, while the normalization is determined from data through dedicated control regions that are enriched in top quark events
Limits are obtained on the product of the cross section and branching fraction for a heavy resonance (X) that decays to HH, WH, or ZH, as reported in figures 5–6
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. Within the solenoid volume are a silicon pixel and strip tracker, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter (HCAL), each composed of a barrel and two endcap sections. Forward calorimeters extend the pseudorapidity (η) coverage provided by the barrel and endcap detectors. Muons are measured in gas-ionization detectors embedded in the steel flux-return yoke outside the solenoid. The CMS two-level trigger system [37] reduces the event rate from the bunch crossing rate of 40 MHz down to around 1 kHz for data storage. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the kinematic variables, can be found in ref. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the kinematic variables, can be found in ref. [38]
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