2,902 research outputs found
Gauge invariant action at the ultraviolet cutoff
We show that it is possible to formulate a gauge theory starting from a local
action at the ultraviolet (UV) momentum cutoff which is BRS invariant. One has
to require that fields in the UV action and the fields in the effective action
are not the same but related by a local field transformation. The few relevant
parameters involved in this transformation (six for the gauge theory),
are perturbatively fixed by the gauge symmetry.Comment: 5 pages, Latex, no figure
Beta function and infrared renormalons in the exact Wilson renormalization group in Yang-Mills theory
We discuss the relation between the Gell-Mann-Low beta function and the
``flowing couplings'' of the Wilsonian action S_\L[\phi] of the exact
renormalization group (RG) at the scale \L. This relation involves the
ultraviolet region of \L so that the condition of renormalizability is
equivalent to the Callan-Symanzik equation. As an illustration, by using the
exact RG formulation, we compute the beta function in Yang-Mills theory to one
loop (and to two loops for the scalar case). We also study the infrared (IR)
renormalons. This formulation is particularly suited for this study since: )
\L plays the r\^ole of a IR cutoff in Feynman diagrams and non-perturbative
effects could be generated as soon as \L becomes small; ) by a
systematical resummation of higher order corrections the Wilsonian flowing
couplings enter directly into the Feynman diagrams with a scale given by the
internal loop momenta; ) these couplings tend to the running coupling at
high frequency, they differ at low frequency and remain finite all the way down
to zero frequency.Comment: 19 pages, 6 figures, LaTex, uses epsfig, rotatin
Factorization and Discrete States in C=1 Superliouville Theory
We study the discrete state structure of superconformal matter
coupled to 2-D supergravity. Factorization properties of scattering amplitudes
are used to identify these states and to construct the corresponding vertex
operators. For both Neveu-Schwarz and Ramond sectors these states are shown to
be organized in
SU(2) multiplets. The algebra generated by the discrete states is computed in
the limit of null cosmological constant.Comment: 23 pages, revtex, CNEA-CAB-92-036 and UPRF-92-35
Dilatation operator and Cayley graphs
We use the algebraic definition of the Dilatation operator provided by
Minahan, Zarembo, Beisert, Kristijansen, Staudacher, proper for single trace
products of scalar fields, at leading order in the large-N 't Hooft limit to
develop a new approach to the evaluation of the spectrum of the Dilatation
operator. We discover a vast number of exact sequences of eigenstates.Comment: 30 pages and 3 eps figures, v2: few typos correcte
Axial anomalies in gauge theory by exact renormalization group method
The global chiral symmetry of a gauge theory is studied in the
framework of renormalization group (RG). The theory is defined by the RG flow
equations in the infrared cutoff \L and the boundary conditions for the
relevant couplings. The physical theory is obtained at \L=0. In our approach
the symmetry is implemented by choosing the boundary conditions for the
relevant couplings not at the ultraviolet point \L=\L_0\to\infty but at the
physical value \L=0. As an illustration, we compute the triangle axial
anomalies.Comment: 11 pages + 1 appended EPS figure, LaTeX, UPRF 94-39
BRS symmetry for Yang-Mills theory with exact renormalization group
In the exact renormalization group (RG) flow in the infrared cutoff
one needs boundary conditions. In a previous paper on Yang-Mills theory
we proposed to use the nine physical relevant couplings of the effective action
as boundary conditions at the physical point (these couplings are
defined at some non-vanishing subtraction point ). In this paper we
show perturbatively that it is possible to appropriately fix these couplings in
such a way that the full set of Slavnov-Taylor (ST) identities are satisfied.
Three couplings are given by the vector and ghost wave function normalization
and the three vector coupling at the subtraction point; three of the remaining
six are vanishing (\eg the vector mass) and the others are expressed by
irrelevant vertices evaluated at the subtraction point. We follow the method
used by Becchi to prove ST identities in the RG framework. There the boundary
conditions are given at a non-physical point , so that
one avoids the need of a non-vanishing subtraction point.Comment: 22 pages, LaTeX style, University of Parma preprint UPRF 94-41
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