Search for single production of scalar leptoquarks in proton-proton collisions ats=8  TeV

Abstract

A search is presented for the production of both first-and second-generation scalar leptoquarks with a final state of either two electrons and one jet or two muons and one jet. The search is based on a data sample of proton-proton collisions at center-of-mass energy ffiffi ffi s p ¼ 8 TeV recorded with the CMS detector and corresponding to an integrated luminosity of 19.6 fb −1 . Upper limits are set on both the first-and secondgeneration leptoquark production cross sections as functions of the leptoquark mass and the leptoquark couplings to a lepton and a quark. Results are compared with theoretical predictions to obtain lower limits on the leptoquark mass. At 95% confidence level, single production of first-generation leptoquarks with a coupling and branching fraction of 1.0 is excluded for masses below 1730 GeV, and second-generation leptoquarks with a coupling and branching fraction of 1.0 is excluded for masses below 530 GeV. These are the best overall limits on the production of first-generation leptoquarks to date.

The leptoquark hunter’s guide: pair production

“…11 in Table V. Note that there is a stronger limit on m Sej ≥ 1.73 TeV from single leptoquark production [59]. However this limit assumes a large coupling (λ ≥ 1) between up quarks and the leptoquark.…”

The case for future hadron colliders from B → K(*)μ+μ− decays

“…There are many dedicated experimental studies of LQs. For some recent examples, CMS have searched for first and second generation LQs in pair production [65][66][67] and single production [68] at 8 TeV centre of mass energy, while ATLAS set limits on the pair production of third generation LQs using 7 TeV data [69] and first and second generation LQs with 13 TeV [70]. A summary of LQ searches by ATLAS and CMS can be found in Ref.…”

“…We extrapolate the current limits from a direct search by CMS for a single scalar LQ produced at 8 TeV with 19.6 fb −1 [68]. CMS places a bound of M LQ 660 GeV for a second generation LQ with coupling to sµ of order unity.…”

Hunting leptoquarks in monolepton searches

“…The LHC collaborations hunt them in pair production processes [9][10][11], with current limits having surpassed those placed by the Tevatron and HERA [12][13][14][15]. Leptoquarks coupling to first-generation quarks and electrons or muons are sought in single production processes, pp → l þ l − j [16]. Furthermore, leptoquarks coupling to electrons are strongly constrained by tests of atomic parity violation (APV) [17].…”