45 research outputs found
Finiteness in N=1 SYM Theories
I present a criterion for all-order finiteness in N=1 SYM theories. Three
applications are given; they yield all-order finite N=1 SYM models with global
symmetries of the superpotential.Comment: 3 pages, plain LaTex, no figure
Exactly Marginal Operators and Duality in Four Dimensional N=1 Supersymmetric Gauge Theory
We show that manifolds of fixed points, which are generated by exactly
marginal operators, are common in N=1 supersymmetric gauge theory. We present a
unified and simple prescription for identifying these operators, using tools
similar to those employed in two-dimensional N=2 supersymmetry. In particular
we rely on the work of Shifman and Vainshtein relating the \bt-function of
the gauge coupling to the anomalous dimensions of the matter fields. Finite N=1
models, which have marginal operators at zero coupling, are easily identified
using our approach. The method can also be employed to find manifolds of fixed
points which do not include the free theory; these are seen in certain models
with product gauge groups and in many non-renormalizable effective theories.
For a number of our models, S-duality may have interesting implications. Using
the fact that relevant perturbations often cause one manifold of fixed points
to flow to another, we propose a specific mechanism through which the N=1
duality discovered by Seiberg could be associated with the duality of finite
N=2 models.Comment: 35 pages, 7 Postscript figures, uses revtex.sty (revised version
corrects some important details, tex problems
Supersymmetric Yang-Mills-Chern-Simons theory
We prove that three-dimensional N=1 supersymmetric Yang-Mills-Chern-Simons
theory is finite to all loops. This leaves open the possibility that different
regularization methods give different finite effective actions. We show that
for this model dimensional regularization and regularization by dimensional
reduction yield the same effective action.Comment: 6 pages, 1 figure, latex, espcrc2. Contribution to the Proceedings of
the 30th Ahrenshoop Symposium on the Theory of Elementary Particles, edited
by D. Lust, H.-J. Otto and G. Weigt, to appear in Nuclear Physics B,
Proceedings Supplemen
Coupling Reduction and the Higgs Mass
Assuming the existence of a functional relation among the Standard Model (SM)
couplings gauge and quartic , we determine the mass of the
Higgs particle. Similar considerations for the top and bottom Yukawa couplings
in the minimal supersymmetric SM lead to the prediction of a narrow window for
, one of the main parameters that determine the light Higgs mass.Comment: 17 pages, 16 figure
Renormalization-Group Improved Effective Potential for Finite Grand Unified Theories in Curved Spacetime
The renormalization-group improved effective potential ---to leading-log and
in the linear curvature approximation--- is constructed for ``finite'' theories
in curved spacetime. It is not trivial and displays a quite interesting,
exponential-like structure ---in contrast with the case of flat spacetime where
it coincides with the classical potential. Several possible cosmological
applications, as curvature-induced phase transitions and modifications of the
values of the gravitational and cosmological constants, are briefly discussed.Comment: 10 pages, LaTeX file, UB-ECM-PF 94/
New N=2 Superconformal Field Theories in Four Dimensions
New examples of N=2 supersymmetric conformal field theories are found as
fixed points of SU(2) N=2 supersymmetric QCD. Relations among the scaling
dimensions of their relevant chiral operators, global symmetries, and Higgs
branches are understood in terms of the general structure of relevant
deformations of non-trivial N=2 conformal field theories. The spectrum of
scaling dimensions found are all those compatible with relevant deformations of
a y^2 = x^3 singular curve.Comment: 17 pages, harvma
supersymmetry and the three loop anomalous dimension for the chiral superfield
We calculate the three loop anomalous dimension for a general
supersymmetric gauge theory. The result is used to probe the possible existence
of renormalisation invariant relationships between the Yukawa and gauge
couplings.Comment: 18 pages. Uses Harvmac. Revised version includes discussion of the
special case of the Wess-Zumino mode
Towards proof of new identity for Green functions in N=1 supersymmetric electrodynamics
For the N=1 supersymmetric massless electrodynamics, regularized by higher
derivatives, we describe a method, by which one can try to prove the new
identity for the Green functions, which was proposed earlier. Using this method
we show that some contribution to the new identity are really 0.Comment: 16 pages, 1 figure, an error corrected, significant change
On the all-order perturbative finiteness of the deformed N=4 SYM theory
We prove that the chiral propagator of the deformed N=4 SYM theory can be
made finite to all orders in perturbation theory for any complex value of the
deformation parameter. For any such value the set of finite deformed theories
can be parametrized by a whole complex function of the coupling constant g. We
reveal a new protection mechanism for chiral operators of dimension three.
These are obtained by differentiating the Lagrangian with respect to the
independent coupling constants. A particular combination of them is a CPO
involving only chiral matter. Its all-order form is derived directly from the
finiteness condition. The procedure is confirmed perturbatively through order
g^6.Comment: LaTeX, 28 pages, 5 figure
Effective action of beta-deformed N = 4 SYM theory: Farewell to two-loop BPS diagrams
Within the background field approach, all two-loop sunset vacuum diagrams,
which occur in the Coulomb branch of N = 2 superconformal theories(including N
= 4 SYM), obey the BPS condition m_3 = m_1 + m_2, where the masses are
generated by the scalars belonging to a background N = 2 vector multiplet.
These diagrams can be evaluated exactly, and prove to be homogeneous quadratic
functions of the one-loop tadpoles J(m_1^2), J(m_2^2) and J(m_3^2), with the
coefficients being rational functions of the squared masses. We demonstrate
that, if one switches on the beta-deformation of the N = 4 SYM theory, the BPS
condition no longer holds, and then generic two-loop sunset vacuum diagrams
with three non-vanishing masses prove to be characterized by the following
property: 2(m_1^2 m_2^2 +m_1^2 m_3^2 +m_2^2 m_3^2) > m_1^4 +m_2^4 +m_3^4. In
the literature, there exist several techniques to compute such diagrams. For
the beta-deformed N = 4 SYM theory, we carry out explicit two-loop calculations
of the Kahler potential and F^4 term. Our considerations are restricted to the
case of beta real.Comment: 42 pages, latex, 1 eps figure; V2: references adde