38 research outputs found
Measurement of forward top pair production in the dilepton channel in <i>pp</i> collisions at âs=13 TeV
Forward top quark pair production is studied in collisions in the final state using a data sample corresponding to an integrated luminosity
of 1.93 fb collected with the LHCb experiment at a centre-of-mass energy
of 13 TeV. The cross-section is measured in a fiducial region where both
leptons have a transverse momentum greater than 20 GeV and a pseudorapidity
between 2.0 and 4.5. The quadrature sum of the azimuthal separation and the
difference in pseudorapidities, denoted , between the two leptons
must be larger than 0.1. The -jet axis is required to be separated from both
leptons by a of 0.5, and to have a transverse momentum in excess of
20 GeV and a pseudorapidity between 2.2 and 4.2. The cross-section is measured
to be where the first uncertainty is statistical, the second is systematic, and
the third is due to the luminosity determination. The measurement is compatible
with the Standard Model prediction.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2017-050.htm
Measurement of CP violation parameters and polarisation fractions in decays
The first measurement of asymmetries in the decay and an updated measurement of its branching
fraction and polarisation fractions are presented. The results are obtained
using data corresponding to an integrated luminosity of of
proton-proton collisions recorded with the LHCb detector at centre-of-mass
energies of and . Together with constraints from , the results are used to constrain additional contributions due
to penguin diagrams in the -violating phase , measured
through decays to charmonium.Comment: 39 pages, 7 tables, 8 figures. All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-034.htm
Differential branching fractions and isospin asymmetries of B â K (*) ÎŒ + ÎŒ â decays
The isospin asymmetries of and
decays and the partial branching fractions of the , and decays are measured as
functions of the dimuon mass squared, . The data used correspond to an
integrated luminosity of 3fb from proton-proton collisions collected
with the LHCb detector at centre-of-mass energies of 7TeV and 8TeV in
2011 and 2012, respectively. The isospin asymmetries are both consistent with
the Standard Model expectations. The three measured branching fractions, while
individually consistent, all favour lower values than their respective Standard
Model predictions.Comment: 25 pages, 4 figures, 7 tables, fix typ
First measurement of the differential branching fraction and asymmetry of the decay
The differential branching fraction with respect to the dimuon invariant mass
squared, and the asymmetry of the decay are
measured for the first time. The CKM matrix elements and ,
and the ratio are determined. The analysis is performed using
proton-proton collision data corresponding to an integrated luminosity of 3.0
fb, collected by the LHCb experiment at centre-of-mass energies of 7 and
8 TeV. The total branching fraction and asymmetry of
decays are measured to be \begin{eqnarray}
\mathcal{B}(B^\pm\to\pi^\pm\mu^+\mu^-) &=& (1.83 \pm 0.24 \pm 0.05) \times
10^{-8}\,\,\,\mathrm{and} \nonumber\\
\mathcal{A}_{C\!P}(B^\pm\to\pi^\pm\mu^+\mu^-) &=& -0.11 \pm 0.12 \pm 0.01\,,
\nonumber \end{eqnarray} where the first uncertainties are statistical and the
second are systematic. These are the most precise measurements of these
observables to date, and they are compatible with the predictions of the
Standard Model
Observations of and decays and searches for other and decays to final states
See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at this https URLInternational audienceA search is performed for the charmless three-body decays of the Î0b and Î0b baryons to the final states Îh+hâČâ, where h(âČ)=Ï or K. The analysis is based on a data sample, corresponding to an integrated luminosity of 3fbâ1 of pp collisions, collected by the LHCb experiment. The Î0bâÎK+Ïâ and Î0bâÎK+Kâ decays are observed for the first time and their branching fractions and CP asymmetry parameters are measured. Evidence is seen for the Î0bâÎÏ+Ïâ decay and limits are set on the branching fractions of Î0b baryon decays to the Îh+hâČâ final states
Search for decays of neutral beauty mesons into four muons
A search for the non-resonant decays and is presented. The measurement is performed using
the full Run 1 data set collected in proton-proton collisions by the LHCb
experiment at the LHC. The data correspond to integrated luminosities of
and collected at centre-of-mass energies of and
, respectively. No signal is observed and upper limits on the
branching fractions of the non-resonant decays at confidence level are
determined to be
\mathcal{B}(B^0_s \rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}) & < 2.5 \times
10^{-9}
\mathcal{B}(B^0 \rightarrow \mu^{+}\mu^{-}\mu^{+}\mu^{-}) & < 6.9 \times
10^{-10}.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-043.htm