Charmless hadronic decays of beauty mesons have been searched for using the data collected with the DELPHI detector at the LEP collider. Several two, three and four-body decay modes have been investigated. Particle identification was used to distinguish the final states with protons, kaons and pions. Three candidate events selected in two-body decay modes are interpreted as evidence for charmless B decays. No excess has been found in higher multiplicity modes and improved upper limits for some of the branching ratios are given.
Two body decay modes. Upper limits at 90% CL. In computing of limits the fractions of B/(d,u)(0,-) and B/S0 mesons were assumed to be 0.39 and 0.12 respectively. Limits are given for the weighted average of the decay rates of the two neutral B mesons.
Three body decay modes. Upper limits at 90% CL.
Four body decay modes. Upper limits at 90% CL.
We present the measurement of the lifetime of the Omega_c we have performed using three independent data samples from two different decay modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Omega_c is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c the shortest living weakly decaying particle observed so far. The short value of the lifetime confirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.
Longitudinally segmented target composed of one copper slab (4mm thick) and3 carbon plates,made of pressed diamond powder with a thickness of 2mm each. The data sample comprises 1.5*10E+8 interactions on the tape which correspond to about 2*10E10 incoming SIGMA- and 3.8*10e+08 interactions.
We present a new measurement of the K L -K S mass difference ( Δm ) using semileptonic decays of neutral kaons. The measurement yields Δm = (0.5274 ± 0.0029 stat. ± 0.0005 syst. ) × 10 10 ħ/s.
No description provided.
None
Charged conjugate state is assumed.
The C12(γ,p0+1)11B differential cross section has been measured for tagged-photon energies of Eγ=44–98 MeV, at laboratory angles of 30°, 45°, 65°, and 90°. Comparison has been made with four different types of calculation. Results from similar calculations for the photoneutron channel have been compared to previously published C12(γ,n0+1)11C data.
No description provided.
Strange and multistrange baryon and antibaryon production has been studied in sulphur sulphur interactions at 200 GeV/ c per nucleon at central rapidity using the CERN Omega Spectrometer. Particle production ratios and transverse mass spectra are presented for Λ, Ξ − , Λ and Ξ − .
No description provided.
No description provided.
No description provided.
None
No description provided.
No description provided.
No description provided.
The cross sections for the charged current processes ${e~{-}p}\rightarrow{\nu_e+hadrons}$ and, for the first time, ${e~{+}p}\rightarrow{\overline{\nu}_e+hadrons}$ are measured at HERA for transverse momenta larger than 25 GeV.
No description provided.
No description provided.
This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in $ep$ interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of $\xpom$, the momentum fraction lost by the proton, of $\beta$, the momentum fraction of the struck quark with respect to $\xpom$, and of $Q~2$. The $\xpom$ dependence is consistent with the form \xpoma where $a=1.30\pm0.08(stat)~{+0.08}_{-0.14}(sys)$ in all bins of $\beta$ and $Q~2$. In the measured $Q~2$ range, the diffractive structure function approximately scales with $Q~2$ at fixed $\beta$. In an Ingelman-Schlein type model, where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule.
No description provided.
No description provided.
No description provided.
A leading order determination of the gluon density in the proton has been performed in the fractional momentum range $1.9 \cdot 10~{-3} < x_{g/p} < 0.18$ by measuring multi-jet events from boson-gluon fusion in deep-inelastic scattering with the H1 detector at the electron-proton collider HERA. This direct determination of the gluon density was performed in a kinematic region previously not accessible. The data show a considerable increase of the gluon density with decreasing fractional momenta of the gluons.
FG is gluon structure function. XPARTON here means the X of the gluon. For the experimental definitions of the XPARTON see paper.
Forum