Kinematic Effects in Radiative Quarkonia Decays

Non-relativistic QCD (NRQCD) predicts colour octet contributions to be significant not only in many production processes of heavy quarkonia but also in their radiative decays. We investigate the photon energy distributions in these processes in the endpoint region. There the velocity expansion of NRQCD breaks down which requires a resummation of an infinite class of colour octet operators to so-called shape functions. We model these non-perturbative functions by the emission of a soft gluon cluster in the initial state. We found that the spectrum in the endpoint region is poorly understood if the values for the colour octet matrix elements are taken as large as indicated from NRQCD scaling rules. Therefore the endpoint region should not be taken into account for a fit of the strong coupling constant at the scale of the heavy quark mass.Comment: LaTeX, 17 pages, 5 figures. The complete paper is also available via the www at http://www-ttp.physik.uni-karlsruhe.de/Preprints

Photon and Z induced heavy charged lepton pair production at a hadron supercollider

We investigate the pair production of charged heavy leptons via photon-induced processes at the proposed CERN Large Hadron Collider (LHC). Using effective photon and Z approximations, rates are given for $L^+L^-$ production due to $\gamma \gamma$ fusion and $Z \gamma$ fusion for the cases of inelastic, elastic and semi-elastic $pp$ collisions. These are compared with the corresponding rates for production via the gluon fusion and Drell-Yan mechanisms. Various $\gamma \gamma$ and $Z \gamma$ differential luminosities for $pp$ collisions are also presented.Comment: 22 pages, RevTex 3.0, 6 uuencoded and compressed postscript figures included. Reference to one paper changed from the original preprint number to the published version. Everything else unchange

Does Efficiency of High Energy Collisions Depend on a Hard Scale?

The multiplicity of charged hadrons in the current fragmentation region of both the c.m.s. and the Breit frame of deep inelastic scattering is calculated and compared with the HERA data. The results are in agreeement with Yang's hypothesis that the efficiency of high energy processes increases at larger momentum transfer.Comment: 11 pages, latex, 3 figures, added one formula, corrected some typo

Dirac Magnetic Monopole Production from Photon Fusion in Proton Collisions

We calculate the lowest order cross--section for Dirac magnetic monopole production from photon fusion in p p-bar collisions at sqrt{s}=1.96 TeV, p p collisions at sqrt{s}=14 TeV, and we compare photon fusion with Drell--Yan (DY) production. We find the total photon fusion cross--section is comparable with DY at sqrt{s}=1.96 TeV and dominates DY by a factor ~50 at sqrt{s}=14 TeV. We conclude that both the photon fusion and DY processes allow for a monopole mass limit m>370 GeV based upon the null results of the recent monopole search at the Collider Detector at Fermilab (CDF). We also conclude that photon fusion is the leading production mechanism to be considered for direct monopole searches at the Large Hadron Collider (LHC).Comment: 9 pages, 4 figures, minor correction, one reference adde