Precise predictions for $A_H q_-$ associated production in the littlest Higgs model with $T$ parity at the LHC

Abstract

In the framework of the littlest Higgs model with $T$ parity, we present complete calculations for the $A_H q_-$ $(q_-=u_-, \bar{u}_-,d_-, \bar{d}_-,c_-, \bar{c}_-,s_-, \bar{s}_-)$ associated production up to the QCD next-to-leading order (NLO) at the CERN Large Hadron Collider with subsequent pure weak decay of $T$-odd mirror quark. We apply the PROSPINO scheme to avoid the double counting problem and to keep the convergence of the perturbative QCD description. The theoretical correlations between the integrated cross section and the factorization and renormalization scale, the global symmetry-breaking scale and the Yukawa coupling parameter are studied separately. We also provide the kinematic distributions of the final decay products. Our numerical results show that the NLO QCD correction reduces the scale uncertainty and enhances the leading-order integrated cross section remarkably, with the $K$ factor varying in the range of $1.41 \sim 1.68$ ($1.58 \sim 1.89$) as the increment of the global symmetry-breaking scale $f$ from $500~{\rm GeV}$ to $1.5~{\rm TeV}$ ($1.1~{\rm TeV}$) at the $\sqrt{s} = 14~{\rm TeV}$ ($8~{\rm TeV}$) LHC. We find that it is possible to select the signal events of the $A_Hq_-$ production from its background by putting proper cuts on the final leading jet and missing energy.