Search for vector-like quarks in events with two oppositely charged leptons and jets in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te}\text {V} $$ s = 13 Te
Author(s)
Sirunyan, A. M; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Dragicevic, M.; Erö, J.; Del Valle, A. E; Flechl, M.; Frühwirth, R.; Ghete, V. M; Hrubec, J.; Jeitler, M.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; ... Show more Show less
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Abstract
A search for the pair production of heavy vector-like partners
$$\mathrm {T}$$
T
and
$$\mathrm {B}$$
B
of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton–proton collisions at
$$\sqrt{s} = 13\,\text {Te}\text {V} $$
s
=
13
Te
. The data sample was collected in 2016 and corresponds to an integrated luminosity of 35.9
$$\,\text {fb}^{-1}$$
fb
-
1
. Final states studied for
$$\mathrm {T} \overline{\mathrm {T}} $$
T
T
¯
production include those where one of the
$$\mathrm {T}$$
T
quarks decays via
$$\mathrm {T} \rightarrow \mathrm {t}\mathrm {Z}$$
T
→
t
Z
and the other via
$$\mathrm {T} \rightarrow \mathrm {b}\mathrm {W}$$
T
→
b
W
,
$$\mathrm {t}\mathrm {Z}$$
t
Z
, or
$$\mathrm {t}\mathrm {H} $$
t
H
, where
$$\mathrm {H}$$
H
is a Higgs boson. For the
$$\mathrm {B} \overline{\mathrm {B}} $$
B
B
¯
case, final states include those where one of the
$$\mathrm {B}$$
B
quarks decays via
$$\mathrm {B} \rightarrow \mathrm {b}\mathrm {Z}$$
B
→
b
Z
and the other
$$\mathrm {B} \rightarrow \mathrm {t}\mathrm {W}$$
B
→
t
W
,
$$\mathrm {b}\mathrm {Z}$$
b
Z
, or
$$\mathrm {b}\mathrm {H} $$
b
H
. Events with two oppositely charged electrons or muons, consistent with coming from the decay of a
$$\mathrm {Z}$$
Z
boson, and jets are investigated. The number of observed events is consistent with standard model background estimations. Lower limits at 95% confidence level are placed on the masses of the
$$\mathrm {T}$$
T
and
$$\mathrm {B}$$
B
quarks for a range of branching fractions. Assuming 100% branching fractions for
$$\mathrm {T} \rightarrow \mathrm {t}\mathrm {Z}$$
T
→
t
Z
, and
$$\mathrm {B} \rightarrow \mathrm {b}\mathrm {Z}$$
B
→
b
Z
,
$$\mathrm {T}$$
T
and
$$\mathrm {B}$$
B
quark mass values below 1280 and 1130
$$\,\text {Ge}\text {V}$$
Ge
, respectively, are excluded.
Date issued
2019-04-26Department
Massachusetts Institute of Technology. Department of PhysicsPublisher
Springer Berlin Heidelberg
Citation
The European Physical Journal C. 2019 Apr 26;79(4):364
Version: Final published version