Problems in the resummation of soft-gluon effects in the transverse-momentum distributions of massive vector bosons in hadronic collisions

We consider the resummation of soft-gluon emission in the transverse-momentum distribution of vector mesons in hadronic collisions. We find that the resummed expression in the impact-parameter formulation has an expansion in \as with factorially growing terms with oscillating signs. These diverging terms arise from the small impact-parameter region of integration, and are of a subleading nature. We also obtain a closed expression for the next-to-leading logarithm resummation in \qt-space, and we study its analytic structure. We find in this case that, although no factorially growing terms are present, there are geometrical singularities that severely restrict the range of applicability of the resummation formula.Comment: 21 pages, 1 figure, plain LaTex with epsfi

Sudakov Logarithm Resummation in Transverse Momentum Space for Electroweak Boson Production at Hadron Colliders

A complete description of W and Z boson production at high-energy hadron colliders requires the resummation of large Sudakov double logarithms which dominate the transverse momentum (q_T) distribution at small q_T. We compare different prescriptions for performing this resummation, in particular implicit impact parameter space resummation versus explicit transverse momentum space resummation. We argue that the latter method can be formulated so as to retain the advantages of the former, while at the same time allowing a smooth transition to finite order dominance at high q_T.Comment: 32 pages, Latex, epsfig, 17 figure

Large pTp_T Hadroproduction of ZZ as a Probe of Gluon Distribution inside Proton

The transverse momentum distribution of single vector boson production at hadron colliders provides useful ways of testing the Standard Model and searching new physics beyond the Standard Model. We study large $p_{_T}$ hadroproduction of $Z$-boson as a probe of gluon distributions inside proton. We investigate how to get initial gluon-involving contributions, or how to subtract quark-quark (or -antiquark) contributions from total cross section. We also investigated the simultaneous measurement of the rapidity and the transverse momentum of the produced $Z$ boson, to obtain momentum fractions of initial partons. And we extracted relevant uncertainties involving in experimental and theoretical analyses. This large $p_{_T}$ hadroproduction of $Z$ can be used as constraints on analyses of global parton (gluon and quarks) distribution functions inside proton.Comment: (a) 13 pages(LaTeX) + 1 figure ps file(3 pages):compressed, uuencoded (b) accepted by Phys.Lett.B. (c) some figures are combined and one is omitted. (d) conclusion part is included into abstrac

Asymptotically finite models and the screening of the cosmological constant by quantum effects

In the framework of the recently proposed asymptotically finite gauge models the cosmological constant is essentially weakened by quantum effects. The next (and more general) claim is that the coupling between quantum fields may suppress their contributions to the induced cosmological constant.Comment: 7 page

Physics in the Real Universe: Time and Spacetime

The Block Universe idea, representing spacetime as a fixed whole, suggests the flow of time is an illusion: the entire universe just is, with no special meaning attached to the present time. This view is however based on time-reversible microphysical laws and does not represent macro-physical behaviour and the development of emergent complex systems, including life, which do indeed exist in the real universe. When these are taken into account, the unchanging block universe view of spacetime is best replaced by an evolving block universe which extends as time evolves, with the potential of the future continually becoming the certainty of the past. However this time evolution is not related to any preferred surfaces in spacetime; rather it is associated with the evolution of proper time along families of world linesComment: 28 pages, including 9 Figures. Major revision in response to referee comment

Varying c and Particle Horizons

We explore what restrictions may impose the second law of thermodynamics on varying speed of light theories. We find that the attractor scenario solving the flatness problem is consistent with the generalized second law at late time.Comment: Latex file, 8 pages, to be published in Physics Letters

Dark matter and dark energy proposals: maintaining cosmology as a true science?

I consider the relation of explanations for the observed data to testability in the following contexts: observational and experimental detection of dark matter; observational and experimental detection of dark energy or a cosmological constant $\Lambda$; observational or experimental testing of the multiverse proposal to explain a small non-zero value of $\Lambda$; and observational testing of the possibility of large scale spatial inhomogeneity with zero $\Lambda$.Comment: 14 pages. Paper for CRAL-IPNL conference "Dark Energy and Dark Matter", Lyon 200

The E5 oncoprotein of BPV-4 does not interfere with the biosynthetic pathway of non-classical MHC class I

The major histocompatibility complex (MHC) class I region in mammals contains both classical and non-classical MHC class I genes. Classical MHC class I molecules present antigenic peptides to cytotoxic T lymphocytes, whereas non-classical MHC class I molecules have a variety of functions. Both classical and non-classical MHC molecules interact with natural killer cell receptors and may under some circumstances prevent cell death by natural killer cytotoxicity. The E5 oncoprotein of BPV-4 down-regulates the expression of classical MHC class I on the cell surface and retains the complex in the Golgi apparatus. The inhibition of classical MHC class I to the cell surface results from both the impaired acidification of the Golgi, due to the interaction of E5 with subunit c of the H+ V-ATPase, and to the physical binding of E5 to the heavy chain of MHC class I. Despite the profound effect of E5 on classical MHC class I, E5 does not retain a non-classical MHC class I in the Golgi, does not inhibit its transport to the cell surface and does not bind its heavy chain. We conclude that, as is the case for HPV-16 E5, BPV-4 E5 does not down-regulate certain non-classical MHC class I, potentially providing a mechanism for the escape of the infected cell from attack by both cytotoxic T lymphocytes and NK cells

The generalized second law in the emergent universe

This paper studies whether the generalized second law of thermodynamics is fulfilled in the transition from a generic initial Einstein static phase to the inflationary phase, with constant Hubble rate, and from the end of the latter to the conventional era of thermal radiation dominated expansion. As it turns out, the said law is satisfied provided the radiation component does not largely contribute to the total energy of the static phase.Comment: 8 pages, 1 figure; to be published in Phys. Letters