Measuring vertical bar V-td vertical bar at the LHC

作者：Alvarez Ezequiel^*; Da Rold Leandro^*; Estevez Mariel^*; Kamenik Jernej F^*

来源：PHYSICAL REVIEW D, 2018, 97(3): 033002.

DOI：10.1103/PhysRevD.97.033002

We propose a direct measurement of the Cabibbo-Kobayashi-Maskawa element V-td at the LHC. Making use of the imbalance between d and (d) over bar quark content in the proton, we show that a nonzero V-td induces a charge asymmetry in the tW associated production. The main backgrounds to this process-t (t) over bar production, and tW-associated production mediated by V-tb-give charge-symmetric contributions at leading order in QCD. Therefore, using specific kinematic features of the signal, we construct a charge asymmetry in the dilepton final state which-due also to a reduction of systematic uncertainties in the asymmetry-is potentially sensitive to V-td suppressed effects. In particular, using signal and background simulations up to the detector level, we show that this new observable could already improve the current direct upper bound on vertical bar V-td vertical bar with existing LHC data. We also project that vertical bar V-td vertical bar values down to similar to 10 times the standard model prediction could be probed at the high-luminosity LHC.

• 出版日期2018-2-12