We have shown recently that the resummation of soft photon contributions leads to a non-exponential decay of the fermion excitations in hot QED plasmas. The retarded propagator of a massless fermion was found to behave as SR(t 1/gT ) ∼ exp{−αTt [ lnωpt+C]}, where ωp = gT/3 is the plasma frequency, α = g2/4π, and C is a constant, independent of g, which was left undefined. This term is computed ...

The real time evolution and relaxation of expectation values of quantum fields and of quantum states are computed as initial value problems by implementing the dynamical renormalization group (DRG). Linear response is invoked to set up the renormalized initial value problem to study the dynamics of the expectation value of quantum fields. The perturbative solution of the equations of motion for...

The standard approach to the infra-red problem is to use the Bloch-Nordsieck trick to handle soft divergences and the Lee-Nauenberg (LN) theorem for collinear singularities. We show that this is inconsistent in the presence of massless initial particles. Furthermore, we show that using the LN theorem with such initial states introduces a non-convergent infinite series of diagrams at any fixed o...

Physics Department and INFN, University of Perugia, Perugia, Italy (Received October 26, 2004) The physics underlying the fall and eventual rise in various total crosssections at high energies has been investigated over a decade using a model based on the Bloch–Nordsieck resummation in QCD. Here a brief review of our latest results is presented and comparison made with experimental data on pp, ...

We point out that, since the colliders' initial states ( e(+)e(-),pp, p&pmacr;,ellipsis) carry a definite non-Abelian flavor, electroweak radiative corrections to inclusive hard cross sections at the TeV scale are affected by peculiar Bloch-Nordsieck violating double logs. We recall the setup of soft cancellation theorems, and we analyze the magnitude of the noncanceling terms in the example of...

The Bloch-Nordsieck model for the parton distribution of hadrons in impact parameter space, constructed using soft gluon summation, is investigated in detail. Its dependence upon the infrared structure of the strong coupling constant αs is discussed, both for finite as well as singular, but integrable, αs. The formalism is applied to the prediction of total proton-proton and proton-antiproton c...

The Bloch-Nordsieck model for the parton distribution of hadrons in impact parameter space, constructed using soft gluon summation, is investigated in detail. Its dependence upon the infrared structure of the strong coupling constant α s is discussed, both for finite as well as singular, but integrable, α s. The formalism is applied to the prediction of total proton-proton and proton-antiproton...