D.A. Ross

mbmτ: A sensitive flavour meter

Abstract We recalculate the complete two-loop correction to the mb/mτ ratio, allowing the possibility of a large t-quark Yukawa coupling constant, comparable to gQCD. We find that our previous stringent limit on the number of flavours becomes even more stringent; i.e., only six flavours are allowed. As a by-product we find that the mass of the t-quark has to be smaller than 155 GeV.

mbmτ in supersymmetric guts: Super flavour-meter

Abstract We calculate the ratio m b m τ up to two loops in supersymmetric grand unified theories. Agreement between theory and experiment imposes a severe limit on the number of flavours: there should be at most six flavours.

Evidence for the discrete asymptotically-free BFKL Pomeron from HERA data

Abstract We show that the next-to-leading-order renormalization-group-improved asymptotically-free BFKL Pomeron provides a good fit to HERA data on virtual photoproduction at small x and large Q 2 . The leading discrete Pomeron pole reproduces qualitatively the Q 2 dependence of the HERA data for x ∼ 10 −3 , and a fit using the three leading discrete singularities reproduces quantitatively the Q 2 and x dependence of the HERA data for x 10 −2 . This fit fixes the phase for all the BFKL wavefunctions at a chosen infrared scale.

On the extraction of αs (MZ0) from LEP jet data

Abstract We propose a method for summing the dominant contributions to the perturbative higher-order effects on jet shape distributions in e + e − annihilation which are due to exponentiation of the leading infrared divergences. We find improved results for the strong interaction coupling constant extracted from various event shape variables by the different groups at LEP, which are in better agreement with each other and with values obtained from other experiments.

Detailed description of the violations of Bjorken scaling in QCD (including higher-order corrections)

Abstract We present a compendium of formulae and parameters required to study the violations of Bjorken scaling, up to and including the subleading (i.e. O(α S )) corrections.

Superstring σ-models from bosonic ones

Abstract We consider the derivation of the background field heterotic σ-model starting from the corresponding bosonic σ-model compactified on the group manifold G [G = E 8 X E 8 or Spin (32)/Z 2 ]. It is necessary not only to identify the SO(8) ⊂ G R gauge potentials with the space-time SO(8) spin connections, but also to identify the Kaluza-Klein scalars with thr G L Yang-Mills field strengths. Similar remarks apply to Type II. This explains the origin of the four-fermion interactions on the world sheet.

On the thrust distribution in e+e− annihilation

Abstract The thrust distribution calculated in perturbative QCD through to O(αs2) is presented. The results, which come from an elaboration of previously published formulae, show that the O(αs2) correction at present energies is large and positive in agreement with the previously obtained results of many groups.

Perturbative estimates of the eigenfunctions of the non-forward BFKL kernel

We discuss, within the context of first order perturbation theory, the correction to the NLO BFKL wavefunction for scattering processes with non-zero momentum transfer, arising from the fact that in NLO the kernel is not covariant under conformal transformations.

Report of the working group on `W mass and QCD' (phenomenology workshop on LEP-2 physics, Oxford, April 1997)

The W mass and QCD working group discussed a wide variety of topics relating to present and future measurements of at LEP2, including QCD backgrounds to production. Particular attention was focused on experimental issues concerning the direct reconstruction and threshold mass measurements, and on theoretical and experimental issues concerning the 4-jet final state. This report summarizes the main conclusions.

Report of the 1997 LEP-2 working group on 'searches'

The Searches Working Group discussed a variety of topics relating to present and future measurements of searches at LEP 2. The individual contributions are included separately.The Searches Working Group discussed a variety of topics relating to present and future measurements of searches at LEP 2. The individual contributions are included separately.