A search for exotic decays of the Higgs boson (
) with a mass of 125
to a pair of light pseudoscalars
is performed in final states where one pseudoscalar decays to two
quarks and the other to a pair ...of muons or
leptons. A data sample of proton-proton collisions at
corresponding to an integrated luminosity of 138
recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (
) on the Higgs boson branching fraction to
and to
via a pair of
s. The limits depend on the pseudoscalar mass
and are observed to be in the range (0.17-3.3)
and (1.7-7.7)
in the
and
final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine upper limits on the branching fraction
at 95%
, with
being a muon or a
lepton. For different types of 2HDM+S, upper bounds on the branching fraction
are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space,
values above 0.23 are excluded at 95%
for
values between 15 and 60
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search is reported for pairs of light Higgs bosons (
) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC
collisions collected with ...the CMS detector at
and corresponding to an integrated luminosity of 138
is used. The search targets events where both
bosons decay into pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a "singlino" of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like
and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the branching fraction of the
in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like branching fraction,
bosons with masses in the range 40-120
arising from the decays of squarks or gluinos with a mass of 1200-2500
are excluded at 95% confidence level.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The production of Z bosons associated with jets is measured in
collisions at
with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3
. The multiplicity ...of jets with transverse momentum
is measured for different regions of the Z boson's
, from lower than 10
to higher than 100
. The azimuthal correlation
between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of
. The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low
regions.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The double differential cross sections of the Drell-Yan lepton pair (
, dielectron or dimuon) production are measured as functions of the invariant mass
, transverse momentum
, and
. The
observable, ...derived from angular measurements of the leptons and highly correlated with
, is used to probe the low-
region in a complementary way. Dilepton masses up to 1
are investigated. Additionally, a measurement is performed requiring at least one jet in the final state. To benefit from partial cancellation of the systematic uncertainty, the ratios of the differential cross sections for various
ranges to those in the Z mass peak interval are presented. The collected data correspond to an integrated luminosity of 36.3
of proton-proton collisions recorded with the CMS detector at the LHC at a centre-of-mass energy of 13
. Measurements are compared with predictions based on perturbative quantum chromodynamics, including soft-gluon resummation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Using a data sample of
proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of
, the
and
decays are observed with significances exceeding ...5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to
and
, where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of
and
mesons,
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for new long-lived particles decaying to leptons using proton-proton collision data produced by the CERN LHC at
is presented. Events are selected with two leptons (an electron and a muon, ...two electrons, or two muons) that both have transverse impact parameter values between 0.01 and 10
and are not required to form a common vertex. Data used for the analysis were collected with the CMS detector in 2016, 2017, and 2018, and correspond to an integrated luminosity of 118 (113)
in the
channel (
and
channels). The search is designed to be sensitive to a wide range of models with displaced
,
, and
final states. The results constrain several well-motivated models involving new long-lived particles that decay to displaced leptons. For some areas of the available phase space, these are the most stringent constraints to date.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Measurements of the associated production of a W boson and a charm (
) quark in proton-proton collisions at a centre-of-mass energy of 8
are reported. The analysis uses a data sample corresponding to ...a total integrated luminosity of 19.7
collected by the CMS detector at the LHC. The W bosons are identified through their leptonic decays to an electron or a muon, and a neutrino. Charm quark jets are selected using distinctive signatures of charm hadron decays. The product of the cross section and branching fraction
, where
or
, and the cross section ratio
are measured in a fiducial volume and differentially as functions of the pseudorapidity and of the transverse momentum of the lepton from the W boson decay. The results are compared with theoretical predictions. The impact of these measurements on the determination of the strange quark distribution is assessed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13
, corresponding to an integrated luminosity of 35.9
, ...are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from
quarks, ...and missing transverse momentum. The search uses data from proton-proton collisions at
collected with the CMS detector, corresponding to an integrated luminosity of 137
. Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at
confidence level on the masses of the top squark and the neutralino up to 925 and 450
, respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850
for neutralino masses below 420
. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4
and 900
respectively for the top squark and the lightest neutralino.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13
at the CERN LHC, corresponding to an integrated luminosity of 137
...collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on the model, the combined result excludes a top squark mass up to 1325
for a massless neutralino, and a neutralino mass up to 700
for a top squark mass of 1150
. Top squarks with masses from 145 to 295
, for neutralino masses from 0 to 100
, with a mass difference between the top squark and the neutralino in a window of 30
around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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