Search for mirror quarks at the LHC

Abstract

Observation of non-zero neutrino masses at a scale ∼ 10 −1 − 10 −2 eV is a major problem in the otherwise highly successful Standard Model. The most elegant mechanism to explain such tiny neutrino masses is the seesaw mechanism with right handed neutrinos. However, the required seesaw scale is so high, ∼ 10 14 GeV, it will not have any collider implications. Recently, an explicit model has been constructed to realize the seesaw mechanism with the right handed neutrinos at the electroweak scale. The model has a mirror symmetry having both the left and right lepton and quark doublets and singlets for the same SU (2) W gauge symmetry. Additional Higgs multiplets have been introduced to realize this scenario. It turns out that these extra Higgs fields also help to satisfy the precision electroweak tests, and other observables. Because the scale of the symmetry breaking is electroweak, both the mirror quark and mirror leptons have masses in the electroweak scale in the range ∼ 150 − 800 GeV. The mirror quarks / leptons decay to ordinary quarks /leptons plus very light neutral scalars. In this work, we calculate the final state signals arising from the pair productions of these mirror quarks and their subsequent decays. We find that these signals are well observable over the Standard Model background for 13 TeV LHC. Depending on the associated Yukawa couplings, these decays can also give rise displaced vertices with long decay length, very different from the usual displaced vertices associated with b decays.

Search for electroweak-scale right-handed neutrinos and mirror charged leptons through like-sign dilepton signals

“…The phenomenology of mirror quarks and leptons was briefly discussed in [9] and a detailed analysis of mirror quarks was presented in [13]. It suffices to mention here that mirror fermions decay into SM fermions through the process q M → qφ S , l M → lφ S with φ S "appearing" as missing energy in the detector.…”

“…In a previous work [13], we discussed the signals of the electroweak ν R model at the LHC arising from the pair productions of the mirror quarks as developed in [9] and the subsequent extensions of the model satisfying all the constraints. We found that for the prompt decays of the mirror quarks plus almost massless neutral scalar (present in the model), the mass of the lightest mirror quark as low as 600 GeV is allowed from the 8 TeV data assuming this branching ratio to be 100%.…”

On neutrino and charged lepton masses and mixings: a view from the electroweak-scale right-handed neutrino model

“…The phenomenology of mirror quarks and leptons was briefly discussed in [11][12][13][14][15] and a detailed analysis of mirror quarks will be presented in [24]. It suffices to mention here that mirror fermions decay into SM fermions through the process q M → qφ S , l M → lφ S with φ S "appearing" as missing energy in the detector.…”

A Model of Neutrino Masses and Mixings and Its Phenomenological Implications

“…Tiny Dirac masses can also be given via small VEVs of Higgs singlets with Y = 0. This is the electroweak scale see-saw mechanism in mirror fermion model which is testable at the LHC [74,119].…”

“…The phenomenology of mirror quarks and leptons was briefly discussed in [70] and a detailed analysis of mirror quarks was presented in [74]. It suffices to mention here that mirror fermions decay into SM fermions through the process q M → qφ S , l M → lφ S with φ S "appearing" as missing energy in the detector.…”