Search for charged-lepton-flavour violating μτqt interactions in top-quark production and decay in pp collisions at √s= 13 TeV with the ATLAS detector at the LHC · arXivDesk
2403.06742Mar 11, 202454 pages in total, author list starting page 37, 7 figures, 9 tables. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2023-23
Search for charged-lepton-flavour violating μτqt interactions in top-quark production and decay in pp collisions at s=13 TeV with the ATLAS detector at the LHC
A search for charged-lepton-flavour violating μτqt (q=u,c) interactions is presented, considering both top-quark production and decay. The data analysed correspond to 140 fb−1 of proton-proton collisions at a centre-of-mass energy of s=
Nearby in the stack
13 TeV recorded with the ATLAS detector at the Large Hadron Collider. The analysis targets events containing two muons with the same electric charge, a hadronically decaying
τ
-lepton and at least one jet, with exactly one
b
-tagged jet, produced by a
μτqt
interaction. Agreement with the Standard Model expectation within
1.6σ
is observed, and limits are set at the 95% CL on the charged-lepton-flavour violation branching ratio of
B(t→μτq)<8.7×10−7
. An Effective Field Theory interpretation is performed yielding 95% CL limits on Wilson coefficients, dependent on the flavour of the associated light quark and the Lorentz structure of the coupling. These range from
∣clequ3(2313)∣/Λ2<0.10 TeV−2
for
μτut
to
∣clequ1(2323)∣/Λ2<1.8 TeV−2
for
μτct
. An additional interpretation is performed for scalar leptoquark production inducing charged lepton flavour violation, with fixed inter-generational couplings. Upper limits on leptoquark coupling strengths are set at the 95% CL, ranging from
λLQ=
1.3 to
λLQ=
3.7 for leptoquark masses between 0.5 and 2.0 TeV.