Search results for "luminosity"
showing 10 items of 560 documents
Search for a Standard Model Higgs Boson inWH→ℓvbb¯inpp¯Collisions ats=1.96 TeV
2009
We present a search for a standard model Higgs boson produced in association with a W boson using 2.7 fb(-1) of integrated luminosity of pp collision data taken at square root s = 1.96 TeV. Limits on the Higgs boson production rate are obtained for masses between 100 and 150 GeV/c(2). Through the use of multivariate techniques, the analysis achieves an observed (expected) 95% confidence level upper limit of 5.6 (4.8) times the theoretically expected production cross section for a standard model Higgs boson with a mass of 115 GeV/c(2).
Search for the Higgs Boson in theH→WW(*)→l+νl−ν¯Decay Channel inppCollisions ats=7 TeVwith the ATLAS Detector
2012
A search for the Higgs boson has been performed in the H -> WW(*()) -> l+vl-(v) over bar channel (l = e/mu) with an integrated luminosity of 2.05 fb(-1) of pp collisions at root s = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 110 GeV< m(H) < 300 GeV. The observations exclude the presence of a standard model Higgs boson with a mass 145 < m(H) < 206 GeV at 95% confidence level.
Combination of searches for anomalous top quark couplings with 5.4 fb−1 of pp¯ collisions
2012
We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in t (t) over bar events. We set upper limits on anomalous tWb coupling form factors using data collected with the DO detector at the Tevatron p (p) over bar collider corresponding to an integrated luminosity of 5.4 fb(-1).
Search for new phenomena in the WW→lνl′ν′ final state in pp collisions at s=7TeV with the ATLAS detector
2013
This Letter reports a search for a heavy particle that decays to WW using events produced in pp collisions at root s = 7 TeV. The data were recorded in 2011 by the ATLAS detector and correspond to an integrated luminosity of 4.7 fb(-1). WW -> lvl'v' (l,l' = e or mu) final states are considered and the distribution of the transverse mass of the W W candidates is found to be consistent with Standard Model expectations. Upper limits on the production cross section times branching ratio into W boson pairs are set for Randall-Sundrum and bulk Randall-Sundrum gravitons, which result in observed 95% CL lower limits on the masses of the two particles of 1.23 TeV and 0.84 TeV, respectively.
Measurement of the W→τντ cross section in pp collisions at s=7 TeV with the ATLAS experiment
2012
The cross section for the production of W bosons with subsequent decay W to tau nu is measured with the ATLAS detector at the LHC. The analysis is based on a data sample that was recorded in 2010 at a proton-proton center-of-mass energy of sqrt(s) = 7 TeV and corresponds to an integrated luminosity of 34 pb^-1. The cross section is measured in a region of high detector acceptance and then extrapolated to the full phase space. The product of the total W production cross section and the W to tau nu branching ratio is measured to be 11.1 +/- 0.3 (stat) +/- 1.7 (syst) +/- 0.4 (lumi) nb.
Joule heating and the thermal evolution of old neutron stars
1998
We consider Joule heating caused by dissipation of the magnetic field in the neutron star crust. This mechanism may be efficient in maintaining a relatively high surface temperature in very old neutron stars. Calculations of the thermal evolution show that, at the late evolutionary stage ($t \geq 10$ Myr), the luminosity of the neutron star is approximately equal to the energy released due to the field dissipation and is practically independent of the atmosphere models. At this stage, the surface temperature can be of the order of $3 \times 10^{4} - 10^{5}$K. Joule heating can maintain this high temperature during extremely long time ($\geq 100$ Myr), comparable with the decay time of the m…
Evidence for the decay X(3872)→ψ(2S)γ
2014
Evidence for the decay mode X(3872) -> psi(2S)gamma in B+ -> X(3872)K+ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton proton collisions, corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb detector, at centre-of-mass energies of 7 and 8 TeV. The ratio of the branching fraction of the X(3872) -> psi(2S)gamma decay to that of the X(3872) -> J/psi gamma decay is measured to be B(X(3872) -> psi(2S)gamma)/B(X(3872) -> J/psi gamma) = 2.46 +/- 0.64 +/- 0.29, where the first uncertainty is statistical and the second is systematic. The measured value does not support a pure D (D) over bar* molecular interpre…
Evolutionary paths of binaries with a neutron star - I. The case of SAX J1808.4 - 3658
2018
The evolutionary status of the low mass X-ray binary SAX J1808.4-3658 is simulated by following the binary evolution of its possible progenitor system through mass transfer, starting at a period of $\sim$6.6 hr. The evolution includes angular momentum losses via magnetic braking and gravitational radiation. It also takes into account the effects of illumination of the donor by both the X-ray emission and the spin down luminosity of the pulsar. The system goes through stages of mass transfer and stages during which it is detached, where only the rotationally powered pulsar irradiates the donor. We show that the pulsar irradiation is a necessary ingredient to reach SAX J1808.4-3658 orbital pe…
Measurement of the absolute branching fraction for Λc+→Λμ+νμ
2017
Abstract We report the first measurement of the absolute branching fraction for Λ c + → Λ μ + ν μ . This measurement is based on a sample of e + e − annihilation data produced at a center-of-mass energy s = 4.6 GeV , collected with the BESIII detector at the BEPCII storage rings. The sample corresponds to an integrated luminosity of 567 pb − 1 . The branching fraction is determined to be B ( Λ c + → Λ μ + ν μ ) = ( 3.49 ± 0.46 ( stat ) ± 0.27 ( syst ) ) % . In addition, we calculate the ratio B ( Λ c + → Λ μ + ν μ ) / B ( Λ c + → Λ e + ν e ) to be 0.96 ± 0.16 ( stat ) ± 0.04 ( syst ) .
The Two‐Component X‐Ray Broadband Spectrum of X Persei Observed byBeppoSAX
1998
We report temporal and broadband (0.1-200 keV) spectral analysis of the Be/X-ray binary X Persei observed by the Narrow Field Instruments (NFI) on board the BeppoSAX satellite. The source luminosity is ~1.2 × 1034 ergs s-1 in the energy range 0.1-10 keV and ~2.4 × 1034 ergs s-1 in the range 0.1-200 keV. The source shows pulsations from 0.1 keV up to 80 keV. No variations of the pulse profile with energy are visible. The barycentric pulse period is 837.376 ± 0.026 s, in agreement with the secular spin-down observed since 1978. The 0.1-10 keV energy spectrum can be well fitted by a power law plus high-energy cutoff, in agreement with previous observations, although at higher energies a hard e…