LHC constraints on scalar diquarks

Abstract

Abstract A number of years ago, low-energy constraints on scalar diquarks, particles that couple to two quarks, were examined. It was found that the two most weakly-constrained diquarks are D u and D d , colour antitriplets that couple to u R i u R j $$ {u}_R^i{u}_R^j $$ and d R i d R j $$ {d}_R^i{d}_R^j $$ , respectively. These diquarks have not been observed at the LHC. In this paper, we add the LHC measurements to the low-energy analysis, and find that the constraints are significantly improved. As an example, denoting x u as the D u coupling to the first and second generations, for M D u $$ {M}_{D^u} $$ = 600 GeV, the low-energy constraint is |x u | ≤ 14.4, while the addition of the LHC dijet measurement leads to |x u | ≤ 0.13–0.15. Further improvements are obtained by adding the measurement of single top production with a p T cut. These new constraints must be taken into account in making predictions for other low-energy indirect effects of diquarks.

Keywords

• Beyond Standard Model
• Heavy Quark Physics