Results are presented from a search for new physics in the final state containing a photon (γ) and missing transverse energy (Ecombininb /(T)). The data correspond to an integrated luminosity of 5.0 ...fb(-1) collected in pp collisions at √s=7 TeV by the CMS experiment. The observed event yield agrees with standard-model expectations for the γ+Ecombininb /(T) events. Using models for the production of dark-matter particles (χ), we set 90% confidence level (C.L.) upper limits of 13.6-15.4 fb on χ production in the γ+Ecombininb /(T) state. These provide the most sensitive upper limits for spin-dependent χ-nucleon scattering for χ masses (M(χ)) between 1 and 100 GeV. For spin-independent contributions, the present limits are extended to M(χ)<3.5 GeV. For models with 3-6 large extra dimensions, our data exclude extra-dimensional Planck scales between 1.64 and 1.73 TeV at 95% C.L.
A search for a standard model Higgs boson produced in association with a top-quark pair and decaying to bottom quarks is presented. Events with hadronic jets and one or two oppositely charged leptons ...are selected from a data sample corresponding to an integrated luminosity of 19.5
fb
-1
collected by the CMS experiment at the LHC in
p
p
collisions at a centre-of-mass energy of 8
TeV
. In order to separate the signal from the larger
t
t
¯
+ jets background, this analysis uses a matrix element method that assigns a probability density value to each reconstructed event under signal or background hypotheses. The ratio between the two values is used in a maximum likelihood fit to extract the signal yield. The results are presented in terms of the measured signal strength modifier,
μ
, relative to the standard model prediction for a Higgs boson mass of 125
GeV
. The observed (expected) exclusion limit at a 95 % confidence level is
μ
<
4.2
(3.3), corresponding to a best fit value
μ
^
=
1
.
2
-
1.5
+
1.6
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for physics beyond the standard model in events with one or more high-momentum Higgs bosons, H, decaying to pairs of b quarks in association with missing transverse momentum is presented. ...The data, corresponding to an integrated luminosity of 35.9 fb^{-1}, were collected with the CMS detector at the LHC in proton-proton collisions at the center-of-mass energy sqrts=13 TeV. The analysis utilizes a new b quark tagging technique based on jet substructure to identify jets from H→bbover ¯. Events are categorized by the multiplicity of H-tagged jets, jet mass, and the missing transverse momentum. No significant deviation from standard model expectations is observed. In the context of supersymmetry (SUSY), limits on the cross sections of pair-produced gluinos are set, assuming that gluinos decay to quark pairs, H (or Z), and the lightest SUSY particle, LSP, through an intermediate next-to-lightest SUSY particle, NLSP. With large mass splitting between the NLSP and LSP, and 100% NLSP branching fraction to H, the lower limit on the gluino mass is found to be 2010 GeV.
A
bstract
A search for neutral Higgs bosons decaying into a
b
b
¯
quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs ...sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan
β
. The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 fb
−1
. The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limits on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios,
m
h
max
,
m
h
mod +
,
m
h
mod −
, light-stau and light-stop. Observed 95% confidence level upper limits on tan
β
, ranging from 14 to 50, are obtained in the
m
h
mod +
benchmark scenario.
A
bstract
A search is presented for the Higgs boson off-shell production in gluon fusion and vector boson fusion processes with the Higgs boson decaying into a W
+
W
−
pair and the W bosons decaying ...leptonically. The data observed in this analysis are used to constrain the Higgs boson total decay width. The analysis is based on the data collected by the CMS experiment at the LHC, corresponding to integrated luminosities of 4.9 fb
−1
at a centre-of-mass energy of 7 TeV and 19.4 fb
−1
at 8 TeV, respectively. An observed (expected) upper limit on the off-shell Higgs boson event yield normalised to the standard model prediction of 2.4 (6.2) is obtained at the 95% CL for the gluon fusion process and of 19.3 (34.4) for the vector boson fusion process. Observed and expected limits on the total width of 26 and 66 MeV are found, respectively, at the 95% confidence level (CL). These limits are combined with the previous result in the ZZ channel leading to observed and expected 95% CL upper limits on the width of 13 and 26 MeV, respectively.
This paper presents a measurement of the inclusive 3-jet production differential cross section at a proton–proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity ...of 5
fb
-
1
collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445–3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to the strong coupling constant
α
S
is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of
α
S
(
M
Z
)
=
0.1171
±
0.0013
(exp)
-
0.0047
+
0.0073
(theo)
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36 TeV were recorded by the CMS detector in December 2009. The trajectories of charged particles produced in the collisions were ...reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field. Results from the Tracker commissioning are presented including studies of timing, efficiency, signal-to-noise, resolution, and ionization energy. Reconstructed tracks are used to benchmark the performance in terms of track and vertex resolutions, reconstruction of decays, estimation of ionization energy loss, as well as identification of photon conversions, nuclear interactions, and heavy-flavour decays.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (
H
) in proton-proton collisions collected by the CMS experiment at the LHC at
s
=
8
TeV
. The data correspond ...to an integrated luminosity of 19.7
fb
-
1
. The search considers
H
H
resonances with masses between 1 and 3
TeV
, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and
t
t
¯
events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 % confidence level for the product of the production cross section and branching fraction
σ
(
g
g
→
X
)
B
(
X
→
H
H
→
b
b
¯
b
b
¯
)
range from 10 to 1.5
\,fb
for the mass of X from 1.15 to 2.0
TeV
, significantly extending previous searches. For a warped extra dimension theory with a mass scale
Λ
R
=
1
TeV
, the data exclude radion scalar masses between 1.15 and 1.55
TeV
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
Double-parton scattering is investigated using events with a Z boson and jets. The Z boson is reconstructed using only the dimuon channel. The measurements are performed with proton-proton ...collision data recorded by the CMS experiment at the LHC at
s
= 13 TeV, corresponding to an integrated luminosity of 35.9 fb
−
1
collected in the year 2016. Differential cross sections of Z+
≥
1 jet and Z+
≥
2 jets are measured with transverse momentum of the jets above 20 GeV and pseudorapidity
|η| <
2
.
4. Several distributions with sensitivity to double-parton scattering effects are measured as functions of the angle and the transverse momentum imbalance between the Z boson and the jets. The measured distributions are compared with predictions from several event generators with different hadronization models and different parameter settings for multiparton interactions. The measured distributions show a dependence on the hadronization and multiparton interaction simulation parameters, and are important input for future improvements of the simulations.
PDF
