Abstract
A phenomenological study of CP-violating dimension-six operators via the e^+e^-rightarrow nu bar{nu } H process is performed in a model-independent Standard Model effective field theory framework at all energy stages of CLIC using the updated baseline integrated luminosities. All signal and relevant background events are generated in MadGraph and passed through PYTHIA for parton showering and hadronization at parton level. Detector effects are considered via tuned CLIC detector cards in Delphes. Since we reconstruct the Higgs boson from a pair of b-jets, limits on CP-violating dimension-six couplings are obtained at three b-tagging working points: tight, medium and loose defined in the CLIC Delphes card for all three energy stages of CLIC. Our best 95 % C.L. limits at the loose working point (90 % b-tagging efficiency) on {tilde{c}}_{HW} and {tilde{c}}_{HB} are [-7.0times 10^{-3};7.0times 10^{-3}] and [-3.0times 10^{-2};3.0times 10^{-2}], respectively at the 3 TeV energy stage of CLIC with an integrated luminosity of 5.0 ab^{-1}. Considering a 0.3 % systematic uncertainty from possible experimental sources worsens the limits on these couplings by a factor of two.
Highlights
The observation of a scalar particle with mass about 125 GeV compatible with the Standard Model (SM) Higgs boson at the Large Hadron Collider (LHC) [1,2] marked a milestone in particle physics, evidence for new physics beyond the SM has not been observed yet in the analysis of combined ATLAS and CMS data to probe the couplings ofThis work was carried out in the framework of the CLICdp Collaboration.In the SM framework, the experimental data is currently consistent with a CP-even hypothesis and the charge conjugation-parity (CP) violation is described by Cabibbo– Kobayashi–Maskawa (CKM) matrix [3,4] with a single complex phase in the Yukawa sector
Since dimension-6 CP-even operators have been studied in Compact Linear Collider (CLIC) [45,50], we investigate the effect of CP-violating dimension-6 operators of the H W W, H γ γ and H Z Z vertices defined by an SM Effective Field Theory (EFT) Lagrangian in the e+e− → νν H production process at the three energy stages of CLIC in this study
We have presented the kinematical distributions of signal and relevant backgrounds; transverse momentum and rapidity of b-tagged quarks, missing energy transverse, scalar sum of the transverse energy and the invariant mass and transverse momentum of the Higgs boson, reconstructed from a pair of b-quarks
Summary
The observation of a scalar particle with mass about 125 GeV compatible with the Standard Model (SM) Higgs boson at the Large Hadron Collider (LHC) [1,2] marked a milestone in particle physics, evidence for new physics beyond the SM has not been observed yet in the analysis of combined ATLAS and CMS data to probe the couplings of. Searches for CP-violating Higgs-gauge boson couplings via higher-dimensional operators were previously performed in many rewarding studies at experimental LHC data [8,9,10,11] and phenomenologically at LHC [12,13,14,15,16,17,18,19,20,21,22,23], at HE-LHC and HL-LHC [24,25,26], at future e+e− [27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42] and ep colliders [43].
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