T. Gottschalk

Fragmentation Function for Heavy Quarks

Abstract The recent conjecture that ν-produced new particles carry most of the energy of the fragmenting heavy quarks is examined in comparison with neutrino dilepton data. The e+ spectrum in νN → μ−e+X and the μ−μ+ azimuthal correlation in νN → μ−μ+X events discriminate against this conjecture for charmed quark fragmentation, but agree with an exponential fall-off of the fragmentation function.

Symmetric Dimuons from Neutrinos

Abstract We show quantitatively that neutrino produced dimuons of charm origin are strongly suppressed in a symmetrical region of the E ( μ − ), E ( μ + ) scatter plot. An appreciable event rate in this region would be a signal for new physics beyond charm.

Are new weak gauge bosons a viable explanation of neutrino trimuon production

Heavy lepton cascade models with new intermediate gauge bosons have been proposed, to avoid constraints on neutrino production of trimuons. Some of these models require production of new hadrons typically with mass ⩾5 GeV in association with heavy leptons. Such mechanisms are strongly constrained by kinematics, compared to heavy production with ordinary hadrons. EHAD < 20 GeV is forbidden; the visible hadron energy for one of five trimuon events falls in this forbidden gap.

Sources of tetramuon production by neutrinos

Abstract We evaluate four sources of tetramuon production by neutrinos: (a) heavy quark cascade, (b) heavy lepton cascade, (c) charm production with radiative pair, (d) charm production plus an associated charm pair. Rates relative to ν → μ − of order (a) 10 −6 , (b) 10 −5 , (c) 10 −7 , (d) 10 −9 , can be obtained. Invariant mass and azimuthal correlation distributions in 4μ events are presented. Relative multimuon rates differ strikingly in the models considered.

Internal Drell-Yan mechanism for neutrino trimuon production

The authors estimate trimuon production nu N to mu - mu - mu +X by the internal Drell-Yan processes nu d to mu -u, uu to mu + mu - and nu u to mu -d, dd to mu + mu -, for d and u quarks in the same target nucleon, using a parton-model approach. This mechanism predicts energetic trimuons with little hadronic excitation at rates of order (3 mu )/( mu ) approximately 10-6.

Effects of multiplicity on charm semileptonic decay distributions

We consider the effects of multiplicity in semileptonic decays of charmed D(1.87) mesons, produced near threshold in e+e− collisions. We calculate the decay distributions from uncorrelated D → (nπ)Kev and resonance dominated D → K∗ev modes. Recent data from DORIS suggest that modes with two or more final hadrons dominate strongly.

Multiple kaon semileptonic decays of the new particles

Abstract The large kaon multiplicity in μ−e+ neutrino events suggests multiple kaon semiloptonic decay modes of new particles. We calculate K and e transverse momentum and Ke invariant mass distributions for various direct and sequential decay mechanisms and compare with the data. The direct decay Y ( c λ ) → K Ke v and the sequential decay Y ∗ ( c n , c p ) → Y ( c λ ) K → K K Ke v 4offer the best overall descriptions of the data. The mode Y → K e v offer the best overall descriptions of the data. The mode Y → K e v disagrees with the mKe distribution.