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: TC2,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) [ SU(2)X U(1) ] SU(2)X U(1) 2

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 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 cancellation can also be understood in terms of the Lagrangian in gauge boson mass eignstates.

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 t- channel 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 4b + l + pt +1jet and backgrounds for the th production. It is found that with 75fb inverse of integrated luminosity, in the parameter space of C=0.8 and f 5 can be achieved