Search results for "Branching"
showing 10 items of 918 documents
Measurement of the Z→ττ cross section with the ATLAS detector
2011
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM
Search for neutral Higgs bosons decaying into four taus at LEP2
2010
A search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV. No excess of events above background is observed, and exclusion limits are placed on the combined production cross section times branching ratio, β2 = σ(e+e -→Zh)/σSM(e+e-→Zh) ×B(h→aa)×B(a→τ+τ-) 2. For mh 1 is excluded at the 95% confidence level.
Search for associated production of charginos and neutralinos in the trilepton final state using 2.3 fb-1 of data
2009
We report the results of a search for associated production of charginos and neutralinos using a data set corresponding to an integrated luminosity of 2.3 fb-1 collected with the D0 experiment during Run II of the Tevatron proton-antiproton collider. Final states containing three charged leptons and missing transverse energy are probed for a signal from supersymmetry with four dedicated trilepton event selections. No evidence for a signal is observed, and we set limits on the product of production cross section and leptonic branching fraction. Within minimal supergravity, these limits translate into bounds on m_0 and m_1/2 that are well beyond existing limits.
Search for the rare semi-leptonic decay J/ψ → D−e+ ν e + c.c.
2021
Abstract Using 10.1 × 109J/ψ events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy $$ \sqrt{s} $$ s = 3.097 GeV and collected with the BESIII detector, we present a search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(J/ψ → D−e+νe + c. c.) < 7.1 × 10−8 is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.
Search for lepton flavor violating decays τ±→l± ω
2008
A search for lepton flavor violating decays of a {tau} to a lighter-mass charged lepton and an {omega} vector meson is performed using 384.1 fb{sup -1} of e{sup +}e{sup -} annihilation data collected with the BABAR detector at the Stanford Linear Accelerator Center PEP-II storage ring. No signal is found, and the upper limits on the branching ratios are determined to be {beta}({tau}{sup {+-}} {yields} e{sup {+-}}{omega}) < 1.1 x 10{sup -7} and {beta}({tau}{sup {+-}} {yields} {mu}{sup {+-}}{omega}) < 1.0 x 10{sup -7} at 90% confidence level.
Jet evolution in a dense medium: event-by-event fluctuations and multi-particle correlations
2017
International audience; We study the gluon distribution produced via successive medium-induced branchings by an energetic jet propagating through a weakly-coupled quark-gluon plasma. We show that under suitable approximations, the jet evolution is a Markovian stochastic process, which is exactly solvable. For this process, we construct exact analytic solutions for all the n-point correlation functions describing the gluon distribution in the space of energy [M. A. Escobedo, E. Iancu, Event-by-event fluctuations in the medium-induced jet evolution, JHEP 05 (2016) 008. arXiv: arXiv:1601.03629 , doi: http://dx.doi.org/10.1007/JHEP05(2016)008 , M. A. Escobedo, E. Iancu, Multi-particle correlati…
Jet transverse fragmentation momentum from h–h correlations in pp and p–Pb collisions
2016
QCD color coherence phenomena, like angular ordering, can be studied by looking at jet fragmentation. As the jet is fragmenting, it is expected to go through two different phases. First, there is QCD branching that is calculable in perturbative QCD. Next, the produced partons hadronize in a non-perturbative way later in a hadronization process. The jet fragmentation can be studied using the method of two particle correlations. A useful observable is the jet transverse fragmentation momentum $j_{\mathrm{T}}$, which describes the angular width of the jet. In this contribution, a differential study will be presented in which separate $j_{\mathrm{T}}$ components for branching and hadronization …
Measurement of the semileptonic branching fraction of the B_{s} meson
2012
We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of CM energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s to l nu X)=9.5 (+2.5/-2.0)(stat)(+1.1/-1.9)(syst)%, where l indicates the average of e and mu.
Precision measurement of the ratio of the charged kaon leptonic decay rates
2013
A precision measurement of the ratio RK of the rates of kaon leptonic decays K+- --> e nu and K+- --> mu nu with the full data sample collected by the NA62 experiment at CERN in 2007-2008 is reported. The result, obtained by analysing ~150000 reconstructed K+- --> e nu candidates with 11% background contamination, is RK = (2.488+-0.010)*10^{-5}, in agreement with the Standard Model expectation.
Search for K+ decays to a muon and invisible particles
2021
The NA62 experiment at CERN reports searches for $K^+\to\mu^+N$ and $K^+\to\mu^+\nu X$ decays, where $N$ and $X$ are massive invisible particles, using the 2016-2018 data set. The $N$ particle is assumed to be a heavy neutral lepton, and the results are expressed as upper limits of ${\cal O}(10^{-8})$ of the neutrino mixing parameter $|U_{\mu4}|^2$ for $N$ masses in the range 200-384 MeV/$c^2$ and lifetime exceeding 50 ns. The $X$ particle is considered a scalar or vector hidden sector mediator decaying to an invisible final state, and upper limits of the decay branching fraction for $X$ masses in the range 10-370 MeV/$c^2$ are reported for the first time, ranging from ${\cal O}(10^{-5})$ t…