Butterworth, Jonathan;
ATLAS Collaboration;
(2023)
Search for flavor-changing neutral-current couplings between the top quark and the
Z
boson with proton-proton collisions at
√
s
=
13
TeV
with the ATLAS detector.
Physical Review D: Particles, Fields, Gravitation and Cosmology
10.1103/PhysRevD.108.032019.
(In press).
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Abstract
A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark, and a Z boson is presented, using proton–proton collision data at √ s = 13 TeV collected by the ATLAS detector at the Large Hadron Collider. The analyzed data set corresponds to an integrated luminosity of 139 fb − 1 . The search targets both single-top-quark events produced as g q → t Z (with q = u , c ) and top-quark-pair events, with one top quark decaying through the t → Z q channel. The analysis considers events with three leptons (electrons or muons), a b -tagged jet, possible additional jets, and missing transverse momentum. The data are found to be consistent with the background-only hypothesis and 95% confidence-level limits on the t → Z q branching ratios, assuming only tensor operators of the Standard Model effective field theory framework contribute to the t Z q vertices. These are 6.2 × 10 − 5 ( 13 × 10 − 5 ) for t → Z u ( t → Z c ) for a left-handed t Z q coupling, and 6.6 × 10 − 5 ( 12 × 10 − 5 ) in the case of a right-handed coupling. These results are interpreted as 95% CL upper limits on the strength of the corresponding couplings, yielding limits for | C ( 13 ) * u W | and | C ( 13 ) * u B | ( | C ( 31 ) u W | and | C ( 31 ) u B | ) of 0.15 (0.16), and limits for | C ( 23 ) * u W | and | C ( 23 ) * u B | ( | C ( 32 ) u W | and | C ( 32 ) u B | ) of 0.22 (0.21), assuming a new-physics energy scale Λ NP of 1 TeV.
Type: | Article |
---|---|
Title: | Search for flavor-changing neutral-current couplings between the top quark and the Z boson with proton-proton collisions at √ s = 13 TeV with the ATLAS detector |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1103/PhysRevD.108.032019 |
Publisher version: | https://doi.org/10.1103/PhysRevD.108.032019 |
Language: | English |
Additional information: | Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3. |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10176352 |
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