3 years ago

# Revisiting scalar leptoquark at the LHC.

We investigate the Standard Model (SM) extended with a colored charged scalar, leptoquark, having fractional electromagnetic charge $-1/3$. Such leptoquarks are mainly searched via the decays into first two generations at the LHC and also recent studies have looked into their third generation decays to obtain the corresponding mass bounds. The indirect searches stringently constrain the leptoquark to decay into first generation. Hence studies for leptoquark, involving decays in both second and third generations are important. In the article, we mainly study the decays of leptoquark into second and third generations via $c\,\mu, t\, \tau$ decay modes. We perform a PYTHIA based simulation considering all the dominant SM backgrounds at the LHC with 14\,TeV center of mass energy. Limits have been calculated for the leptoquark mass that can be probed at the LHC with an integrated luminosity of 3000 fb$^{-1}$. The leptoquark mass reconstructed from its decay products into third generation, has the maximum reach. However, $\mu + c$ channel, comprising of a very hard muon and $c$-jet produces a much cleaner mass peak. Single leptoquark production in association with a $\mu$ or $\nu_\tau$ provide some unique signatures that can also be probed at the LHC.