A
bstract
Dimuon and dielectron mass spectra, obtained from data resulting from proton-proton collisions at 8 TeV and recorded by the CMS experiment, are used to search for both narrow resonances and ...broad deviations from standard model predictions. The data correspond to an integrated luminosity of 20.6 (19.7) fb
−1
for the dimuon (dielectron) channel. No evidence for non-standard-model physics is observed and 95% confidence level limits are set on parameters from a number of new physics models. The narrow resonance analyses exclude a Sequential Standard Model Z
SSM
′
resonance lighter than 2.90 TeV, a superstring-inspired Z
ψ
′
lighter than 2.57 TeV, and Randall-Sundrum Kaluza-Klein gravitons with masses below 2.73, 2.35, and 1.27 TeV for couplings of 0.10, 0.05, and 0.01, respectively. A notable feature is that the limits have been calculated in a model-independent way to enable straightforward reinterpretation in any model predicting a resonance structure. The observed events are also interpreted within the framework of two non-resonant analyses: one based on a large extra dimensions model and one based on a quark and lepton compositeness model with a left-left isoscalar contact interaction. Lower limits are established on M
S
, the scale characterizing the onset of quantum gravity, which range from 4.9 to 3.3 TeV, where the number of additional spatial dimensions varies from 3 to 7. Similarly, lower limits on Λ, the energy scale parameter for the contact interaction, are found to be 12.0 (15.2) TeV for destructive (constructive) interference in the dimuon channel and 13.5 (18.3) TeV in the dielectron channel.
A search for new physics is performed using events with two isolated same-sign leptons, two or more jets, and missing transverse momentum. The results are based on a sample of proton-proton ...collisions at a center-of-mass energy of 13 TeV recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 inverse femtobarns. Multiple search regions are defined by classifying events in terms of missing transverse momentum, the scalar sum of jet transverse momenta, the transverse mass associated with a W boson candidate, the number of jets, the number of b quark jets, and the transverse momenta of the leptons in the event. The analysis is sensitive to a wide variety of possible signals beyond the standard model. No excess above the standard model background expectation is observed. Constraints are set on various supersymmetric models, with gluinos and bottom squarks excluded for masses up to 1300 and 680 GeV, respectively, at the 95% confidence level. Upper limits on the cross sections for the production of two top quark-antiquark pairs (119 fb) and two same-sign top quarks (1.7 pb) are also obtained. Selection efficiencies and model independent limits are provided to allow further interpretations of the results.
A search for direct production of the supersymmetric (SUSY) partners of electrons or muons is presented in final states with two opposite-charge, same-flavour leptons (electrons and muons), no jets, ...and large missing transverse momentum. The data sample corresponds to an integrated luminosity of 35.9 fb-1 of proton–proton collisions at $\sqrt{s}$=13TeV , collected with the CMS detector at the LHC in 2016. The search uses the MT2 variable, which generalises the transverse mass for systems with two invisible objects and provides a discrimination against standard model backgrounds containing W bosons. The observed yields are consistent with the expectations from the standard model. The search is interpreted in the context of simplified SUSY models and probes slepton masses up to approximately 290, 400, and 450 GeV, assuming right-handed only, left-handed only, and both right- and left-handed sleptons (mass degenerate selectrons and smuons), and a massless lightest supersymmetric particle. Limits are also set on selectrons and smuons separately. Furthermore, these limits show an improvement on the existing limits of approximately 150 GeV.
Dijet production in PbPb collisions at a nucleon–nucleon center-of-mass energy of 2.76 TeV is studied with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 150 ...μb−1 is analyzed. Jets are reconstructed using combined information from tracking and calorimetry, using the anti-kT algorithm with R=0.3. The dijet momentum balance and angular correlations are studied as a function of collision centrality and leading jet transverse momentum. For the most peripheral PbPb collisions, good agreement of the dijet momentum balance distributions with pp data and reference calculations at the same collision energy is found, while more central collisions show a strong imbalance of leading and subleading jet transverse momenta attributed to the jet-quenching effect. The dijets in central collisions are found to be more unbalanced than the reference, for leading jet transverse momenta up to the highest values studied.
A search for the production of Higgs boson pairs in proton–proton collisions at a centre-of-mass energy of 13 TeV is presented, using a data sample corresponding to an integrated luminosity of 35.9 ...fb-1 collected with the CMS detector at the LHC. Events with one Higgs boson decaying into two bottom quarks and the other decaying into two τ leptons are explored to investigate both resonant and nonresonant production mechanisms. The data are found to be consistent, within uncertainties, with the standard model background predictions. For resonant production, upper limits at the 95% confidence level are set on the production cross section for Higgs boson pairs as a function of the hypothesized resonance mass and are interpreted in the context of the minimal supersymmetric standard model. For nonresonant production, upper limits on the production cross section constrain the parameter space for anomalous Higgs boson couplings. The observed (expected) upper limit at 95% confidence level corresponds to about 30 (25) times the prediction of the standard model.
The WZ production cross section in proton–proton collisions at s=13 TeV is measured with the CMS experiment at the LHC using a data sample corresponding to an integrated luminosity of 2.3 fb−1. The ...measurement is performed in the leptonic decay modes WZ→ℓνℓ′ℓ′, where ℓ,ℓ′=e,μ. The measured cross section for the range 60<mℓ′ℓ′<120 GeV is σ(pp→WZ)=39.9±3.2(stat) (syst)−3.1+2.9±0.4(theo)±1.3(lumi) pb, consistent with the standard model prediction.
A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the
M
T
2
variable. The results are based on a sample of ...proton–proton collisions collected in 2016 at a center-of-mass energy of 13
TeV
with the CMS detector and corresponding to an integrated luminosity of 35.9
fb
-1
. No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of
R
-parity conserving supersymmetry. Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550)
GeV
. Mass limits as high as 1070 (1175)
GeV
are set on the masses of top (bottom) squarks. Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions.
Measurements are presented of associated production of a
W
boson and a charm quark (
W
+
c
) in proton–proton collisions at a center-of-mass energy of 13
Te
. The data correspond to an integrated ...luminosity of 35.7
fb
-
1
collected by the CMS experiment at the CERN LHC. The
W
bosons are identified by their decay into a muon and a neutrino. The charm quarks are tagged via the full reconstruction of
D
∗
(
2010
)
±
mesons that decay via
D
∗
(
2010
)
±
→
D
0
+
π
±
→
K
∓
+
π
±
+
π
±
. A cross section is measured in the fiducial region defined by the muon transverse momentum
p
T
μ
>
26
Ge
, muon pseudorapidity
|
η
μ
|
<
2.4
, and charm quark transverse momentum
p
T
c
>
5
Ge
. The inclusive cross section for this kinematic range is
σ
(
W
+
c
)
=
1026
±
31
(stat)
+
76
-
72
(syst) pb
. The cross section is also measured differentially as a function of the pseudorapidity of the muon from the
W
boson decay. These measurements are compared with theoretical predictions and are used to probe the strange quark content of the proton.
A search for heavy, right-handed neutrinos,
N
ℓ
(
ℓ
=
e
,
μ
), and right-handed
W
R
bosons, which arise in the left-right symmetric extensions of the standard model, has been performed by the CMS ...experiment. The search was based on a sample of two lepton plus two jet events collected in proton–proton collisions at a center-of-mass energy of 8
TeV
corresponding to an integrated luminosity of 19.7
fb
-
1
. For models with strict left-right symmetry, and assuming only one
N
ℓ
flavor contributes significantly to the
W
R
decay width, the region in the two-dimensional
(
M
W
R
,
M
N
ℓ
)
mass plane excluded at a 95 % confidence level extends to approximately
M
W
R
=
3.0
TeV
and covers a large range of neutrino masses below the
W
R
boson mass, depending on the value of
M
W
R
. This search significantly extends the
(
M
W
R
,
M
N
ℓ
)
exclusion region beyond previous results.
Results are reported on a search for decays of a pseudoscalar A boson into a Z boson and a light scalar h boson, where the Z boson decays into a pair of oppositely-charged electrons or muons, and the ...h boson decays into b anti-b. The search is based on data from proton-proton collisions at a center-of-mass energy sqrt(s)=8 TeV collected with the CMS detector, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The h boson is assumed to be the recently discovered standard model-like Higgs boson with a mass of 125 GeV. With no evidence for signal, upper limits are obtained on the product of the production cross section and the branching fraction of the A boson in the Zh channel. Results are also interpreted in the context of two Higgs doublet models.
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