3,703 research outputs found
Observation of the decay with the CMS detector
The observation of the boson rare decay to a meson and
two oppositely charged same-flavour leptons, , where
represents the sum of and
, and , is
presented. The data sample used corresponds to an integrated luminosity of
of proton-proton collisions at a center-of-mass energy
of accumulated by the CMS experiment at the LHC. The signal
is observed with a significance in excess of 5 standard deviations. Removing
contributions from decays to , the signal
is interpreted as being entirely from
, with its fiducial branching
fraction relative to that of the decay
measured to be
This result is obtained
with the assumption of no polarisation, where extreme
polarisation scenarios can create to variations
Identification of circles from datapoints using Gaussian sums
We present a pattern recognition method which use datapoints on a plane and
estimates the parameters of a circle. MC data are generated in order to test
the method's efficiency over noise hits, uncertainty in the hits positions and
number of datapoints. The scenario were the hits from a quadrant of the circle
are missing is also considered. The method proposed is proven to be robust,
accurate and very efficient.Comment: 4 pages, 5 figure
Performance Studies of a Micromegas Chamber in the ATLAS Environment
Five small prototype micromegas detectors were positioned in the ATLAS
detector during Large Hadron Collider running at and . A double drift gap detector was
placed in front of the electromagnetic calorimeter and four detectors on the ATLAS Small Wheel, the first station of the
forward muon spectrometer. The one attached to the calorimeter was exposed to
interaction rates of about at
two orders of magnitude
higher than the rates in the Small Wheel. We present the results from
performance studies carried out using data collected with these detectors and
we also compare the currents drawn by the detector installed in front of the
electromagnetic calorimeter with the luminosity measurement in ATLAS.Comment: 9 pages, 11 figure
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