Lepton spectrum in semileptonic b-decay

We present some results from the computation of the charged lepton energy distribution in the decay b → c + $\text{l}$^? + $\text{ν}$ taking into account first order QCD corrections.     

Measurement of mass and lifetime of hadronically produced charmed F mesons

We have observed three unique decays of F mesons into KKπ and five unique decays of D mesons into KKπ using the NA11 spectrometer together with a telescope of high-resolution silicon microstrip detectors. The mass value obtained for the F meson is (1975 ± 4) MeV, the lifetime (3.2±_1.3^3..0)×10^?13 s.     

Lattice fermions in euclidean space-time

A very short proof of a no-go theorem for putting fermions on a lattice is given using the Poincaré-Hopf theorem. The no-go theorem forbids the lattice formulation of theories with handed fermions without species doubling. Examples of such theories are chiral invariant QCD and the Weinberg-Salam-Glashow model. We give arguments why it could be possible to circumvent the no-go theorem by relaxing one of the assumptions, viz. bilinearity of the action in the fermion fields.     

A study of final states with a large transverse momentum particle from proton-proton collisions at 24 GeV/c

Events with a large transverse momentum (>1 GeV/c) pion or nucleon have been selected from the data of a high-statistics pp bubble chamber experiment (√s=6.84 GeV). Only events in which all secondary particles could be identified were used. One finds that fewer pions are produced in the azimuthal hemisphere containing the large transverse momentum particle than in the opposite hemisphere. An indication for coplanarity is found. Most pions associated with a large transverse momentum pion are emitted with small absolute c.m. rapidities, whereas those associated with large transverse momentum nucleons show some back-to-back structure. Various results of this investigation are similar to those obtained at the ISR. Most of the findings are compatible with predictions from an independent emission model.     

Ω− produced in K−p reactions at 4.2 GeV/c

Forty $\text{Ω}{}^{\mathrm{?}}$ events have been observed in a large (133 events/βb) experiment at 4.2 GeV/c incident K^? momentum. Thirty nine of the events come from the three-body reaction $\text{K}{}^{\mathrm{?}}\text{p}\text{→Ω}{}^{\mathrm{?}}\text{K}{}^{\mathrm{+}}\text{K}{}^0$. The $\text{Ω}{}^{\mathrm{?}}$ is mainly produced in the forward hemisphere (direction of the incident K^?). The lifetime is measured to be τ = (0.75 _+0.14?0.11 × 10^?10 sec substantially less than the Particle Data Group value of (1.3 _?0.3^+0.2) × 10^?10 sec. The mass is determined to be 1671.7 ± 0.6 MeV, in good agreement with other determinations. The decay asymmetry parameter α (for the decay mode $\text{Ω}{}^{\mathrm{?}}\text{→ Λ}\text{K}{}^{\mathrm{?}}$) is found to be ?0.2 ± 0.4.     

Charged multiplicities in K−p interactions at 100 GeV/c

The charged multiplicity distribution is presented for K^?p interactions produced in the hydrogen bubble chamber, BEBC, using an r.f. separated, tagged K^? beam of 110 GeV/c momentum. A comparison with K⁺p, πp and pp data at lower energies shows that the main features of the multiplicity distributions depend on energy and charge of the incident particles, but not on their strangeness. At high energies, only the energy is important.     

Isospin analysis of the reactions pp→N(Nπ) at 12 and 24 GeV/c

The reaction pp → nucleon + nucleon + pion at 12 and 24 GeV/c is analyzed in terms of the isospin amplitudes for the production of the (Nπ) system. The energy dependence of the $\text{I(}\text{N}\text{π) =}\text{1}\text{2}$ amplitude is weak, while the $\text{I(}\text{N}\text{π) =}\text{3}\text{2}$ contribution shows the strong energy dependence known from meson exchange reactions. The slope parameter B of the dσ/dt′ distributions of the $\text{I(}\text{N}\text{π)=}\text{1}\text{2}$ contribution is a strong function of the (Nπ) mass, decreasing sharply from about 12 GeV^?2 at threshold to about 4 GeV^?2 above 1700 MeV. Comparing our results for the $\text{I(}\text{N}\text{π) =}\text{1}\text{2}$ cross section with those of similar investigations in πp and Kp reactions, we find that factorisation is valid within experimental errors. The results support the conclusion that the $\text{I(}\text{N}\text{π) =}\text{1}\text{2}$ contribution is dominated by diffraction dissociation of the proton.     

Jets and correlations in large pT reactions

Recent experimental data on correlations in large transverse momentum reactions are analyzed in a two-jet picture. Scaling in jet fragmentation is shown to account well for the existing data. The formulae that are given can be used as a basis for a more detailed analysis of the dynamics. A particular result is that we predict that a two-jet structure can also be produced in events where it is not required that any single hadron has large p_T, with a cross section as large as $\text{1}\text{10}$ mb or more (at ISR energies with the total transverse momentum of each jet ?2.5 GeV/c).     

Study of correlation effects in high-multiplicity proton-proton reactions at 12 and 24 GeV/c

In this paper we study correlations in multiparticle final states from pp interactions at 12 and 24 GeV/c. In an attempt to distinguish true dynamical correlations from the consequences of kinematics together with P_T damping and the leading-particle effect, we compare the data with an independent-emission model which reproduces the single-particle spectra and also with a model that simulates a fragmentation mechanism. We investigate the forward-backward particle configurations and in particular the multiplicity imbalance and charge transfer, defining forward-backward by the largest rapidity gap as well as simply by c.m.s. hemispheres. We also study clustering by looking at distributions of the dispersions in longitudinal rapidity. From the comparison of the data with the models we find clear evidence for dynamical correlations of a sort one would expect from fragmentation-type mechanisms. We also find indications of non-fragmentation formation of neutral meson clusters.     

Search for charmed hadrons in neutral strange particle events in pp interactions at 19 GeV/c

A search for charmed hadrons has been made in proton-proton interactions at 19 GeV/c using events with one or two observed neutral strange particles. No evidence for charmed particles has been found. Upper limits for their production cross sections are presented.