77 research outputs found

### Gauge-Invariant Differential Renormalization: Abelian Case

A new version of differential renormalization is presented. It is based on
pulling out certain differential operators and introducing a logarithmic
dependence into diagrams. It can be defined either in coordinate or momentum
space, the latter being more flexible for treating tadpoles and diagrams where
insertion of counterterms generates tadpoles. Within this version, gauge
invariance is automatically preserved to all orders in Abelian case. Since
differential renormalization is a strictly four-dimensional renormalization
scheme it looks preferable for application in each situation when dimensional
renormalization meets difficulties, especially, in theories with chiral and
super symmetries. The calculation of the ABJ triangle anomaly is given as an
example to demonstrate simplicity of calculations within the presented version
of differential renormalization.Comment: 15 pages, late

### On evaluation of two-loop self-energy diagram with three propogator

Small momentum expansion of the "sunset" diagram with three different masses
is obtained. Coefficients at powers of $p^2$ are evaluated explicitly in terms
of dilogarithms and elementary functions. Also some power expansions of
"sunset" diagram in terms of different sets of variables are given.Comment: 9 pages, LaTEX, MSU-PHYS-HEP-Lu3/9

### Neighbours of Einstein's Equations: Connections and Curvatures

Once the action for Einstein's equations is rewritten as a functional of an
SO(3,C) connection and a conformal factor of the metric, it admits a family of
``neighbours'' having the same number of degrees of freedom and a precisely
defined metric tensor. This paper analyzes the relation between the Riemann
tensor of that metric and the curvature tensor of the SO(3) connection. The
relation is in general very complicated. The Einstein case is distinguished by
the fact that two natural SO(3) metrics on the GL(3) fibers coincide. In the
general case the theory is bimetric on the fibers.Comment: 16 pages, LaTe

### New directions in antimalarial target validation

Introduction: Malaria is one of the most prevalent human infections worldwide with over 40% of the world's population living in malaria-endemic areas. In the absence of an effective vaccine, emergence of drug-resistant strains requires urgent drug development. Current methods applied to drug target validation, a crucial step in drug discovery, possess limitations in malaria. These constraints require the development of techniques capable of simplifying the validation of Plasmodial targets. Areas covered: The authors review the current state of the art in techniques used to validate drug targets in malaria, including our contribution - the protein interference assay (PIA) - as an additional tool in rapid in vivo target validation. Expert opinion: Each technique in this review has advantages and disadvantages, implying that future validation efforts should not focus on a single approach, but integrate multiple approaches. PIA is a significant addition to the current toolset of antimalarial validation. Validation of aspartate metabolism as a druggable pathway provided proof of concept of how oligomeric interfaces can be exploited to control specific activity in vivo. PIA has the potential to be applied not only to other enzymes/pathways of the malaria parasite but could, in principle, be extrapolated to other infectious diseases

### On the non-Abelian Stokes theorem for SU(2) gauge fields

We derive a version of non-Abelian Stokes theorem for SU(2) gauge fields in
which neither additional integration nor surface ordering are required. The
path ordering is eliminated by introducing the instantaneous color orientation
of the flux. We also derive the non-Abelian Stokes theorem on the lattice and
discuss various terms contributing to the trace of the Wilson loop.Comment: Latex2e, 0+14 pages, 3 figure

### About the Poisson Structure for D4 Spinning String

The model of D4 open string with non-Grassmann spinning variables is
considered. The non-linear gauge, which is invariant both Poincar\'e and scale
transformations of the space-time, is used for subsequent studies. It is shown
that the reduction of the canonical Poisson structure from the original phase
space to the surface of constraints and gauge conditions gives the degenerated
Poisson brackets. Moreover it is shown that such reduction is non-unique. The
conseption of the adjunct phase space is introduced. The consequences for
subsequent quantization are discussed. Deduced dependence of spin $J$ from the
square of mass $\mu^2$ of the string generalizes the ''Regge spectrum`` for
conventional theory.Comment: 23 page

### Differential Equations for Definition and Evaluation of Feynman Integrals

It is shown that every Feynman integral can be interpreted as Green function
of some linear differential operator with constant coefficients. This
definition is equivalent to usual one but needs no regularization and
application of $R$-operation. It is argued that presented formalism is
convenient for practical calculations of Feynman integrals.Comment: pages, LaTEX, MSU-PHYS-HEP-Lu2/9

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