Abstract
A model-independent search for a narrow resonance produced in proton–proton collisions at s=8 TeV and decaying to a pair of 125 GeV Higgs bosons that in turn each decays into a bottom quark–antiquark pair is performed by the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 17.9 fb−1. No evidence for a signal is observed. Upper limits at a 95% confidence level on the production cross section for such a resonance, in the mass range from 270 to 1100 GeV, are reported. Using these results, a radion with decay constant of 1 TeV and mass from 300 to 1100 GeV, and a Kaluza–Klein graviton with mass from 380 to 830 GeV are excluded at a 95% confidence level.
Highlights
Following the discovery of a Higgs boson (H) at the CERN LHC [1,2,3], with mass around 125 GeV and properties so far consistent with the standard model (SM) of particle physics, it has become important to search for new resonances that decay into pairs of such Higgs bosons
Several well-motivated hypotheses of physics beyond the standard model posit narrow-width resonances that decay into pairs of Higgs bosons, and could be produced with large enough cross sections to be probed with existing data
The main challenge of this search is to distinguish the signal of four bottom quarks in the final state that hadronize into jets (b jets) from the copious multijet background described by quantum chromodynamics (QCD) in pp collisions. We address this challenge by suitable event selection criteria that include dedicated b-jet identification techniques and a model of the multijet background that is validated in data control regions
Summary
Following the discovery of a Higgs boson (H) at the CERN LHC [1,2,3], with mass around 125 GeV and properties so far consistent with the standard model (SM) of particle physics, it has become important to search for new resonances that decay into pairs of such Higgs bosons. To search for signal events at various mass hypotheses, we fit the mX distribution in data events in the SR to a parametric model for the signal peak on top of parametric models appropriate for components of the SM background This procedure is performed for the LMR, the MMR, and the HMR separately. Since the uncertainty in the reconstructed mass of the Higgs boson candidate due to the measurement of jet direction is smaller than that due to the measurement of jet energy, this constraint mainly affects the latter This fit improves the invariant mass resolution of the reconstructed signal resonance by 20–40%, depending on the mass hypothesis. We build the parametric model for each signal mass hypothesis by fitting the shape of the mX distribution of simulated events that are accepted by the selection criteria and corrected for differences between data and simulation. This mass shift is found to be linear in mX and occurs due to the aforementioned constraint of jet momenta to mH
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
