79 research outputs found
Anomaly Mediation and Dimensional Transmutation
We show how a sparticle spectrum characteristic of anomaly mediation can
arise from a theory whose Lagrangian contains no explicit mass scale. The scale
of supersymmetry breaking is governed by the gravitino mass, which is the
vacuum expectation value of the F-term of the conformal compensator field, and
the tachyonic slepton problem is resolved by the breaking of a U(1) gauge
symmetry at a scale determined by dimensional transmutation.Comment: 12 pages, 1 figure. v2 has added preprint number and acknowledgement
Renormalisation of the Fayet-Iliopoulos D-term
We consider the renormalisation of the Fayet-Iliopoulos D-term in a
softly-broken Abelian supersymmetric theory. We show that there exists (at
least through three loops) a renormalisation group invariant trajectory for the
coefficient of the D-term, corresponding to the conformal anomaly solution for
the soft masses and couplings.Comment: 11 pages, TeX, Uses Harvmac (big). References added, minor
corrections (including a sign error for the zeta(3) terms), and discussion of
scheme dependence corrected and amplifie
One-loop renormalisation of N=1/2 supersymmetric gauge theory
We show that N=1/2 supersymmetric gauge theory is renormalisable at one loop,
but only after gauge invariance is restored in a non-trivial fashion.Comment: 11 pages, including 3 figures. Plain TeX. Uses Harvmac and epsf.
Minor changes and reference adde
Clarifying Some Remaining Questions in the Anomaly Puzzle
We discuss several points that may help to clarify some questions that remain
about the anomaly puzzle in supersymmetric theories. In particular, we consider
a general N=1 supersymmetric Yang-Mills theory. The anomaly puzzle concerns the
question of whether there is a consistent way to put the R-current and the
stress tensor in a single supercurrent, even though in the classical theory
they are in the same supermultiplet. As is well known, the classically
conserved supercurrent bifurcates into two supercurrents having different
anomalies in the quantum regime. The most interesting result we obtain is an
explicit expression for the lowest component of one of the two supercurrents in
4-dimensional spacetime, namely the supercurrent that has the energy-momentum
tensor as one of its components. This expression for the lowest component is an
energy-dependent linear combination of two chiral currents, which itself does
not correspond to a classically conserved chiral current. The lowest component
of the other supercurrent, namely, the R-current, satisfies the Adler-Bardeen
theorem. The lowest component of the first supercurrent has an anomaly that we
show is consistent with the anomaly of the trace of the energy-momentum tensor.
Therefore, we conclude that there is no consistent way to put the R-current and
the stress tensor in a single supercurrent in the quantized theory. We also
discuss and try to clarify some technical points in the derivations of the
two-supercurrents in the literature. These latter points concern the
significance of infrared contributions to the NSVZ beta-function and the role
of the equations of motion in deriving the two supercurrents.Comment: 22 pages, no figure. v2: minor changes. v3: sections re-organized.
new subsections (IVA, IVB) added. references adde
Asymptotic Pad\'e Approximants and the SQCD -function
We present a prediction for the four loop -function for SQCD based on
the method of Asymptotic Pad\'e Approximants.Comment: 8 pages, including 2 figures. Plain TeX. Uses Harvmac and eps
Reduction of Couplings in Quantum Field Theories with applications in Finite Theories and the MSSM
We apply the method of reduction of couplings in a Finite Unified Theory and
in the MSSM. The method consists on searching for renormalization group
invariant relations among couplings of a renormalizable theory holding to all
orders in perturbation theory. It has a remarkable predictive power since, at
the unification scale, it leads to relations between gauge and Yukawa couplings
in the dimensionless sectors and relations involving the trilinear terms and
the Yukawa couplings, as well as a sum rule among the scalar masses and the
unified gaugino mass in the soft breaking sector. In both the MSSM and the FUT
model we predict the masses of the top and bottom quarks and the light Higgs in
remarkable agreement with the experiment. Furthermore we also predict the
masses of the other Higgses, as well as the supersymmetric spectrum, both being
in very confortable agreement with the LHC bounds on Higgs and supersymmetric
particles.Comment: 18 pages, 4 figures. To appear in the proceedings of LT-10, Varna.
Based on invited talks given at: LT-10, Varna; PACT-2013, Madrid; SQS'2013,
Dubna; CORFU 2013, Corfu, and in several invited seminar
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
Infra-red stability of Yukawa and soft-breaking fixed points
We investigate the infra-red stability of the fixed points in the evolution
of the Yukawa couplings, -parameters and soft scalar masses in a broad class
of supersymmetric theories. We show that the issue of stability is essentially
determined in all three cases by the eigenvalues of the same matrix. In a very
wide range of physically interesting theories it follows that, in the
asymptotically free case, the existence of stable infra-red fixed points for
the Yukawa couplings implies stable infra-red fixed points for the
-parameters and soft scalar masses.Comment: 12 pages, tex, Uses harvmac (big). Errors corrected in Eqs.
(33)-(35), and some references adde
Yukawa Textures and the mu-term
We show how with an anomaly-free U(1), simple assumptions concerning the
origin of Yukawa textures and the Higgs mu-term lead to the prediction of a new
physics scale of 10^8GeV and automatic conservation of baryon number.Comment: 12 pages, uses Harvmac (option "b"
The effective potential and the renormalisation group
We discuss renormalisation group improvement of the effective potential both
in general and in the context of scalar \p^4 and the Standard Model.
In the latter case we find that absolute stability of the electroweak vacuum
implies that , for \as (M_Z) = 0.11. We point out
that the lower bound on {\it decreases\/} if \as (M_Z) is increased.Comment: 22 pages plus three PostScript figures (appended), Liverpool preprint
LTH 288, University of Michigan preprint UM-TH-92-2
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