Backward particle production in neutrino neon interactions

Backward proton and pion production is studied in ν and \(\bar v\) charged current interactions in neon. The results are compared with other experiments and theory. The complete backward proton data is compatible with protons produced by reinteractions in the nucleus. However in events with only one proton, muon variables appear correlated to those for the backward proton, as expected by the two-nucleon correlation model.     

Coherent single pion production by antineutrino charged current interactions and test of PCAC

The cross section for coherent production of a single π^? meson in charged current antineutrino interactions on neon nuclei has been measured in BEBC to be (175±25) 10^?40 cm²/neon nucleus, averaged over the energy spectrum of the antineutrino wide band beam at the CERN SPS; this corresponds to (0.9±0.1) % of the total charged current \(\bar v_\mu \) cross section. The distributions of kinematical variables are in agreement with theoretical predictions based on the PCAC hypothesis and the meson dominance model; in particular, theQ ² dependence is well described by a propagator containing a massm=(1.35±0.18) GeV. The absolute value of the cross section is also in agreement with the model. This analysis thus provides a test of the PCAC hypothesis in the antineutrino energy range 5–150 GeV.     

Measurement of the forward-backward asymmetry of charm and bottom quarks at theZ pole usingD*± mesons

The forward-backward asymmetries for the processes and at theZ resonance are measured using identifiedD ^*± mesons. In 905,000 selected hadronic events, taken in 1991 and 1992 with the DEL-PHI detector at LEP, 4757D ^*+D ⁰⁺ decays are reconstructed. Thec andb quark forward-backward asymmetries are determined to be:

B* production in Z decays

The decayB ^*B has been observed with the DELPHI detector at LEP, where theB ^* meson is produced inZ boson decays. The combination of inclusively reconstructedB mesons with well-measured converted photons yields a measurement of the flavour-averagedB ^*-B mass difference of 45.5±0.3 (stat.) ±0.8 (syst.) MeV/c². 95% confidence level upper limits at 6 MeV/c² are placed on both the isospin (i.e.B ⁺-B ⁰) and theB _s -B _ud splitting of the mass difference. The production ratio ofB ^* toB mesons inZ decays is measured to be 0.72±0.03 (stat.) ±0.06 (syst.). Limits on the production cross-section of other hypothetical excitedB hadron states decaying radiatively are established. The differentialB ^* cross section has been measured to be in good agreement with the averageb fragmentation, yielding an average fractionalB ^* energy of x _E =0.695±0.009 (stat.) ±0.013 (syst.). From the decay angular distribution the relative contribution of longitudinalB ^* polarisation states is measured to be _L/(_L + _T) = 0.32 ± 0.04 (stat.) ±0.03 (syst.).CICYT_AEN93-0832     

A precision measurement of the average lifetime ofB hadrons

The average lifetime ofB hadrons was measured using data collected with the DELPHI detector at the LEP collider during 1991 and 1992. The measurement was performed using two different anayses. The first method was an improvement on a previous technique, which used charged particle impact parameter distributions. This analysis measured an average lifetime forB hadrons of

Arzneimittel und pharmazeutische Pr?parate

Ohne Zusammenfassung     

Search for a standard model Higgs boson in the H→ZZ→ℓ(+)ℓ(-)νν decay channel with the ATLAS detector

A search for a heavy standard model Higgs boson decaying via H→ZZ→→?(+)?(-)νν, where ?=e, μ, is presented. It is based on proton-proton collision data at √s=7 TeV, collected by the ATLAS experiment at the LHC in the first half of 2011 and corresponding to an integrated luminosity of 1.04 fb(-1). The data are compared to the expected standard model backgrounds. The data and the background expectations are found to be in agreement and upper limits are placed on the Higgs boson production cross section over the entire mass window considered; in particular, the production of a standard model Higgs boson is excluded in the region 340相似文献   

Observation of a centrality-dependent dijet asymmetry in lead-lead collisions at sqrt[S(NN)] =2.76 TeV with the ATLAS detector at the LHC

By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.     

Search for the standard model Higgs boson in the diphoton decay channel with 4.9 fb(-1) of pp collision data at √s=7 TeV with ATLAS

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9 fb(-1) collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7 TeV. In the diphoton mass range 110-150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110-150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113-115 GeV and 134.5-136 GeV.