Siniša Veseli

W and Z transverse momentum distributions: resummation in qT-space

We describe an alternative approach to the prediction of W and Z transverse momentum distributions based on an extended version of the DDT formula. The resummation of large logarithms, mandatory at small qT, is performed in qT-space, rather than in the impact parameter b. The leading, next-to-leading and next-to-next-to-leading towers of logarithms are identical in the b-space and qT-space approaches. We argue that these terms are sufficient for W and Z production in the region in which perturbation theory can be trusted. Direct resummation in qT-space provides a unified description of vector boson transverse momentum distributions valid at both large and small qT.

Vector boson production in hadronic collisions

Abstract We consider the production of γ*, W and Z vector bosons in hadron-hadron collisions in perturbative QCD. We present results from a new numerical program which gives a full description of the production of the vector bosons and of their decay products. At small qT the calculation includes resummation of large logarithms and non-perturbative effects. The resummation is matched with the full O(αs) calculation. In addition, the program correctly reproduces the known O(αs) cross section when integrated over qT. Besides presenting results for W and Z production at the Tevatron, we also review constraints on the non-perturbative functions using fixed-target data on lepton pair production, and make several observations on this topic.

Distributed data access and resource management in the D0 SAM system

SAM (Sequential Access through Meta-data) is the data access and job management system for the D0 high energy physics experiment at Fermilab. The SAM system is being developed and used to handle the Petabyte-scale experiment data, accessed by hundreds of D0 collaborators scattered around the world. In this paper, we present solutions to some of the distributed data processing problems from the perspective of real experience dealing with mission-critical data. We concentrate on the distributed disk caching, resource management and job control. The system has elements of Grid computing and has features applicable to data-intensive computing in general.

Decay constants of P- and D-wave heavy-light mesons.

We investigate decay constants of P- and D-wave heavy-light mesons within the mock-meson approach. Numerical estimates are obtained using the relativistic quark model. We also comment on recent calculations of heavy-light pseudo-scalar and vector decay constants.

Excited glue and the vibrating flux tube

Abstract Recent lattice results for the energy of gluonic excitations as a function of quark separation are shown to correspond to transverse relativistic flux tube vibration modes. For large quark separations all states appear to degenerate into a few categories which are predicted uniquely, given the ground state.

Analytic quantization of the QCD string

We perform an analytic semi-classical quantization of the straight QCD string with one end fixed and a massless quark on the other, in the limits of orbital and radial dominant motion. We compare our results to the exact numerical semi-classical quantization. We observe that the numerical semi-classical quantization agrees well with our exact numerical canonical quantization.

Radiative rare B decays revisited

We reexamine contributions of higher K-resonances to the radiative rare decays b → sγ in the limit where both the b- and s-quark are considered heavy. Using form factor definitions consistent with the HQET covariant trace formalism, we find significant disagreement with previous work and excellent agreement with experimental results. In particular, the two largest fractions of the inclusive b → sγ branching ratio are found to be (16.8 |+- 6.4)% for B → K∗ (892)γ and (6.2 ± 2.9)% for B → K2∗ (1430)γ decays. We also compare the contribution from the radiative decays into the eight K-meson states to the inclusive experimental b → sγ mass distribution.

Strong radiative corrections to W b bbar production in p pbar collisions

We calculate the strong radiative corrections to the process p{bar p}{r_arrow}W({r_arrow}e{nu})g{sup {asterisk}}({r_arrow}b{bar b}). At the Fermilab Tevatron, this process is the largest background to the associated Higgs boson production p{bar p} {r_arrow}W({r_arrow}e{nu})H({r_arrow}b{bar b}). The calculation is based on the subtraction procedure, and the corrections are found to be significant. {copyright} {ital 1999} {ital The American Physical Society}

Gluonic hadrons and charmless B decays

Hybrid charmonium with mass {approximately} 4 GeV could be produced via a c{anti c} color-octet component in b {r_arrow} c{anti c}s. These states could be narrow and could have a significant branching ratio to light hadrons, perhaps enhanced by glueballs. Decays to gluonic hadrons could make a sizable contribution to B {r_arrow} no charm decays. Experimental signatures and search strategies are discussed.

From scalar to string confinement

We outline a connection between scalar quark confinement, a phenomenologically successful concept heretofore lacking fundamental justification, and QCD. Although scalar confinement does not follow from QCD, there is an interesting and close relationship between them. We develop a simple model intermediate between scalar confinement and the QCD string for illustrative purposes. Finally, we find analytically the bound state spectrum of the light degrees of freedom for a spinless, massless quark in scalar, time-component vector, and string confinement through semi-classical quantization.