Associated production of the Higgs boson and a
Associated production of the Higgs boson and a single top quark in the littlest Higgs model at Large Hadron Collier Shuo Yang
Promblems in SM • No fundamental scalars observed in nature • No explanation of dynamics responsible for EWSB • Hierarachy Problem • Trivality Problem • Neutrino mass • Dark matter. . . .
Possible Solutions • • • SUSY Technicolor: TC 2 , top seesaw Extra Dimensions: flat, wraped Higgsless Model Little Higgs ……
LHC May Tell Us what is the nature !
Little higgs models Motivation: hierarchy problem Basic Idea: higgs is a goldstone boson Mechanism: collective symmetry breaking Littlest Higgs Model SU(5) SO(5) 2 [ SU(2)X U(1) ] SU(2)X U(1)
We find that in a large part of the parameter space the cross section of th production in s-channel and t-channel production can deviate largely from the SM prediction.
th production signal and background Our signal is Backgrounds
• We find that in a large part of the parameter space the cross section of th production in s-channel and tchannel production can deviate largely from the SM prediction. • Different from the case in SM, in LH model both the cross sections in s-channel and t-channel are larger than that in W-associated process in a large part of the parameter space. • We also consider the signal 4 b + l + pt +1 jet and backgrounds for the th production. It is found that with 30 fb inverse of integrated luminosity, in the parameter space of C=0. 8 and f<1. 62, 3 sigma deviation can be achieved. With 75 fb inverse of luminosity, 5 sigma deviation can be achieved
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Collective symmetry breaking If there is only g 2. the original SU(5) is explicitly broken to SU(3)×SU(2)×U(1), where the SU(3) acts on the first three indices. In this limit, The Higgs doublet h shifts under part of the SU(3), and so it is forbidden from picking up a potential. The same symmetry argument applies when only g 1 is turned on. The fact that tells us that even when all couplings are turned on, the Higgs does not receive quadratically divergent contributions to its mass-squared at one loop
The new gauge bosons ; The scalars H and a triplet Ф; The cancellation can also be understood in terms of the Lagrangian in gauge boson mass eignstetes.
- Slides: 14