Search results for "annihilation"
showing 10 items of 1016 documents
Moments of event shapes in electron-positron annihilation at next-to-next-to-leading order
2009
This article gives the perturbative next-to-next-to-leading order results for the moments of the most commonly used event shape variables associated to three-jet events in electron-positron annihilation: thrust, heavy jet mass, wide jet broadening, total jet broadening, C parameter and the Durham three-to-two-jet transition variable.
Higgs-boson production in association with three jets via gluon fusion at the LHC: Gluonic contributions
2013
Higgs production in association with three jets via gluon fusion is an important channel for the measurement of the CP properties of the Higgs particle at the LHC. In this paper, we go beyond the heavy top effective theory approximation and include at LO the full mass dependence of the top- and bottom-quark contributions. We consider the dominant subchannel gg -> Hggg which involves the manipulation of massive rank-5 hexagon integrals. Furthermore, we present results for several differential distributions and show deviations from the effective theory as large as 100% at high p(T) for light Higgs masses.
Higgs CP properties using the tau decay modes at the ILC
2013
We investigate the prospects of determining the CP nature of the 126 GeV neutral spin-0 (Higgs) boson h, discovered at the LHC, at a future linear collider. We consider the production of h by the Higgsstrahlung process and its subsequent decays to tau leptons. We investigate how precisely a possible pseudoscalar component of h can be detected by the measurement of a suitably defined angular distribution, if all major decay modes of the tau lepton are used. From our numerical simulations, we estimate the expected precision to the scalar-pseudoscalar mixing angle, including estimates of the background and of measurement uncertainties, to be 2.8 degree for Higgs-boson production at a center-of…
Search For Light Neutral Higgs Particles Produced In Z0-decays
1990
A search for the neutral Higgs boson in Z0-decays has been performed using the DELPHI detector at the Large Electron Positron collider (LEP) at CERN. We looked for the decay of Z0 into a neutral Higgs particle and a pair of fermions. No events fulfilled the criteria for H0-production. Our results, which are based on an integrated luminosity of 530 nb-1, exclude a minimal Standard Model Higgs boson with a mass in the range 210 MeV/c2 to 14 GeV/c2 at 95% confidence level.
Searching for Invisibly Decaying Higgs Bosons at LEP II
1996
We study the potential of LEP II to unravel the existence of invisibly decaying Higgs bosons, predicted in a wide class of models. We perform a model independent analysis, focusing our attention to the final state topologies exhibiting $b \bar{b}$ or $\ell^+ \ell^-$ ($\ell=\mu$ or $e$) pairs and missing energy. We carefully evaluate the signals and backgrounds, choosing appropriate cuts to enhance the discovery limits. Our results demonstrate that LEP II is capable of discovering such a Higgs boson for a wide range of masses and couplings.
Search for doubly charmed baryonsΞcc+andΞcc++inBABAR
2006
We search for the production of doubly charmed baryons in e(+)e(-) annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of 232 fb(-1) recorded with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center. We search for Xi(+)(cc) baryons in the final states Lambda K-+(c)-pi(+) and Xi(0)(c)pi(+), and Xi(++)(cc) baryons in the final states Lambda K-+(c)-pi(+)pi(+) and Xi(0)(c)pi(+)pi(+). We find no evidence for the production of doubly charmed baryons.
Search for the neutral Higgs bosons of the MSSM in e(+)e(-) collisions at root s from 130 to 172 GeV
1997
The process e(+)e(-) --> hA is used to search for the Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM), in the b (b) over bar b (b) over bar and tau(+)tau(-)b (b) over bar final states, The search is performed in the data collected by the ALEPH experiment at LEP, at centre-of-mass energies between 130 and 172 GeV and with a total luminosity of 27.2 pb(-1). No candidate events are found in either of the final states, in agreement with the expected background of 0.91 events from all Standard Model processes. Combined with searches for e(+)e(-) --> hZ, this results in a 95% C.L. lower limit on the masses of both h and A of 62.5 GeV/c(2), for tan beta > 1. (C) 1997 Elsevier Scie…
Measurement of the W mass in e(+)e(-) collisions at production threshold
1997
In June 1996, the LEP centre-of-mass energy was raised to 161 GeV. Pair production of W bosons in e(+)e(-) collisions was observed for the first time by the LEP experiments. An integrated luminosity of 11 pb(-1) was recorded in the ALEPH detector, in which WW candidate events were observed. In 6 events both Ws decay leptonically. In 16 events, one W decays leptonically, the other into hadrons. In the channel where both Ws decay into hadrons, a signal was separated from the large background by means of several multi-variate analyses. The W pair cross-section is measured to be sigma(ww) = 4.23 +/- 0.73(stat.) +/- 0.19(syst.) pb. From this cross-section, the W mass is derived within the framew…
Search for supersymmetric particles using acoplanar charged-particle pairs from Z0 decays
1990
We have performed a search for supersymmetric particles using acoplanar pairs of oppositely-charged particles in decays of the Z0. In 0.53 pb−1 of integrated luminosity near the Z0 peak, we observe two events where approximately four are expected from background, allowing limits to be extended on combined photino and slepton masses, and also on combined photino and chargino masses.
Search for $\gamma\gamma$ decays of a Higgs boson produced in association with a fermion pair in $e^+ e^-$ collisions at LEP
2000
A serach for gamma gamma decays of Higgs boson is performed in the data sample collected at LEP with the ALEPH detector between 1991 and 1999. This corresponds to an integrated luminosity of 672 pb-1 centre-of-mass energies ranging from 88 to 202 GeV. The search is based on topologies arising from a Higgs boson produced in association with a fermion pair via the Higgs-strahlung process e+e- -> Hffbar, with ffbar = nunubar, e+e-, mu+mu-, tau+tau- or qqbar... (CERN)