We calculate the impact factor coupling a virtual photon to a gluon via a massive quark-antiquark pair at LL order, but with the imposition of the correct gluon kinematics. Exact analytical results are presented in triple Mellin space with respect to scaled Bjorken x, gluon transverse momentum and heavy quark mass. The application of these results to the calculation of approximate NLL coefficie...

This review covers some of the developments in basic theory of astronomical masers over the past ten years. Topics included are the effects of three dimensional geometry and polarization, with special emphasis on the differences between maser and non-maser radiation. 1. Maser Absorption Coefficient in Three Dimensions The absorption coefficient κ describes the coupling between particles and rad...

We simulate self-avoiding walks on a cubic lattice and determine the second virial coefficient for walks of different lengths. This allows us to determine the critical value of the renormalized four-point coupling constant in the three-dimensional N -vector universality class for N = 0. We obtain ḡ = 1.4005(5), where ḡ is normalized so that the three-dimensional field-theoretical β-function beh...

We introduce a new parameterization of four-fermion operator matrix elements which does not involve quark masses and thus allows a reduction of systematic uncertainties. In order to simplify the matching between lattice and continuum renormalization schemes, we express our results in terms of renormalization group invariant B-parameters which are renormalization-scheme and scale independent. As...

We discuss in detail the possibility of determining dynamicaly the gravitino mass m3/2, which is related to the supersymmetry breaking scale, within the minimal supersymmetric standard model (MSSM). Using the complete MSSM spectrum, we minimize the vacuum energy including oneloop corrections and a cosmological term of O(m3/2) induced by the underlying fundamental theory. We find that both terms...

Path coupling is a useful technique for simplifying the analysis of a coupling of a Markov chain. Rather than defining and analysing the coupling on every pair in Ω ×Ω , where Ω is the state space of the Markov chain, analysis is done on a smaller set S ⊆Ω ×Ω . If the coefficient of contraction β is strictly less than one, no further analysis is needed in order to show rapid mixing. However, if...

We give a brief overview of the status of perturbative QCD calculations for deep-inelastic scattering. The radiative corrections to the Wilson coefficients are generally available to next-to-next-to-leading order in QCD and we address the accuracy of the strong coupling constant, the parton distributions of the nucleon and the heavy quark masses which is required for precision predictions. We a...

The dependence of the nuclear force on standard model parameters plays an important role in bounding time and space variations of fundamental couplings over cosmological time scales. We discuss the quark-mass dependence of deuteron and di-neutron binding in a systematic chiral expansion. The leading quark-mass dependence of the nuclear force arises from one-pion exchange and from local quark-ma...

Evolution of the parton densities at NLO in αS using W̃ 2 = Q2(1 − z)/z instead of the usual Q2 for the scale of the running coupling αS is investigated. While this renormalisation scale change was originally proposed as the relevant one for x → 1, we explore the consequences for all x with this choice. While it leads to no improvement to the description of DIS data, the nature of the gluon at l...

We derive the algebraic relations of alternating and non-alternating finite harmonic sums up to the sums of depth 6. All relations for the sums up to weight 6 are given in explicit form. These relations depend on the structure of the index sets of the harmonic sums only, but not on their value. They are therefore valid for all other mathematical objects which obey the same multiplication relati...