Measurements are presented of the triple-differential cross section for inclusive isolated-photon+jet events in
collisions at
TeV as a function of photon transverse momentum (
), photon ...pseudorapidity (
), and jet pseudorapidity (
). The data correspond to an integrated luminosity of
that probe a broad range of the available phase space, for
and
,
,
, and jet transverse momentum,
, > 25
. The measurements are compared to next-to-leading order perturbative quantum chromodynamics calculations, which reproduce the data within uncertainties.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The exclusive photoproduction of
meson states from protons,
(with
), is studied in ultraperipheral
Pb collisions at a centre-of-mass energy per nucleon pair of
. The measurement is performed using ...the
decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6
. Differential cross sections as functions of the
transverse momentum squared
, and rapidity
, are presented. The
photoproduction cross section is extracted in the rapidity range
, which corresponds to photon-proton centre-of-mass energies in the range
. The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Exclusive
photoproduction is measured for the first time in ultraperipheral pPb collisions at
with the CMS detector. The cross section
is
b at
for photon-proton centre-of-mass energies
between 29 and
.... The differential cross section
is measured in the interval
as a function of
, where
is the squared four-momentum transfer at the proton vertex. The results are compared with previous measurements and theoretical predictions. The measured cross section
has a power-law dependence on the photon-proton centre-of-mass, consistent with electron-proton collision measurements performed at HERA. The
dependence of the exponential slope of the differential cross section
is also measured.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search is presented for the single production of vector-like quarks in proton-proton collisions at
. The data, corresponding to an integrated luminosity of 35.9
, were recorded with the CMS ...experiment at the LHC. The analysis focuses on the vector-like quark decay into a top quark and a
boson, with one muon or electron in the final state. The mass of the vector-like quark candidate is reconstructed from hadronic jets, the lepton, and the missing transverse momentum. Methods for the identification of
quarks and of highly Lorentz boosted hadronically decaying top quarks and
bosons are exploited in this search. No significant deviation from the standard model background expectation is observed. Exclusion limits at 95% confidence level are set on the product of the production cross section and branching fraction as a function of the vector-like quark mass, which range from 0.3 to 0.03
for vector-like quark masses of 700 to 2000
. Mass exclusion limits up to 1660
are obtained, depending on the vector-like quark type, coupling, and decay width. These represent the most stringent exclusion limits for the single production of vector-like quarks in this channel.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A search for the pair production of heavy vector-like partners
and
of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton-proton collisions at
. The data ...sample was collected in 2016 and corresponds to an integrated luminosity of 35.9
. Final states studied for
production include those where one of the
quarks decays via
and the other via
,
, or
, where
is a Higgs boson. For the
case, final states include those where one of the
quarks decays via
and the other
,
, or
. Events with two oppositely charged electrons or muons, consistent with coming from the decay of a
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
and
quarks for a range of branching fractions. Assuming 100% branching fractions for
, and
,
and
quark mass values below 1280 and 1130
, respectively, are excluded.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta,
, is presented. The measurement considers events where the two ...leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of
and corresponding to an integrated luminosity of
are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with the measurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region
. The 2- and 3-jet measurements are not simultaneously described by any of models.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Observation of tt[over ¯]H Production Adam, W; D'Hondt, J; Brun, H ...
Physical review letters,
2018-Jun-08, 20180608, Letnik:
120, Številka:
23
Journal Article
Recenzirano
The observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data at center-of-mass energies of ...sqrts=7, 8, and 13 TeV, corresponding to integrated luminosities of up to 5.1, 19.7, and 35.9 fb^{-1}, respectively. The data were collected with the CMS detector at the CERN LHC. The results of statistically independent searches for Higgs bosons produced in conjunction with a top quark-antiquark pair and decaying to pairs of W bosons, Z bosons, photons, τ leptons, or bottom quark jets are combined to maximize sensitivity. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance from the standard model for a Higgs boson mass of 125.09 GeV is 4.2 standard deviations. The combined best fit signal strength normalized to the standard model prediction is 1.26_{-0.26}^{+0.31}.
Measurements of inclusive isolated-photon and photon+jet production in proton-proton collisions at Formula omitted are presented. The analysis uses data collected by the CMS experiment in 2015, ...corresponding to an integrated luminosity of 2.26 Formula omitted. The cross section for inclusive isolated photon production is measured as a function of the photon transverse energy in a fiducial region. The cross section for photon+jet production is measured as a function of the photon transverse energy in the same fiducial region with identical photon requirements and with the highest transverse momentum jet. All measurements are in agreement with predictions from next-to-leading-order perturbative QCD.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Measurements are presented of associated production of a
boson and a charm quark (
) in proton-proton collisions at a center-of-mass energy of 13
. The data correspond to an integrated luminosity of ...35.7
collected by the CMS experiment at the CERN LHC. The
bosons are identified by their decay into a muon and a neutrino. The charm quarks are tagged via the full reconstruction of
mesons that decay via
. A cross section is measured in the fiducial region defined by the muon transverse momentum
, muon pseudorapidity
, and charm quark transverse momentum
. The inclusive cross section for this kinematic range is
. The cross section is also measured differentially as a function of the pseudorapidity of the muon from the
boson decay. These measurements are compared with theoretical predictions and are used to probe the strange quark content of the proton.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not ...known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.
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![Observation of tt[over ¯]H ...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0031-9007/small "Observation of tt[over ¯]H Production")