119 research outputs found
Infrared Consistency of NSVZ and DRED Supersymmetric Gluodynamics
Pade approximant methods are applied to known terms of the DRED beta-
function for N = 1 supersymmetric SU(3) Yang-Mills theory. Each of the [N|M]
approximants with N + M less than or equal to 4 (M not equal to zero)
constructed from this series exhibits a positive pole which precedes any zeros
of the approximant, consistent with the same infrared-attractor pole behaviour
known to characterise the exact NSVZ beta-function. A similar Pade-approximant
analysis of truncations of the NSVZ series is shown consistently to reproduce
the geometric-series pole of the exact NSVZ beta function.Comment: LaTeX, 15 page
Dynamical spin effects in the pion
We take into account dynamical spin effects in the holographic light-front
pion wavefunction in order to predict the pion radius, decay constant, the pion
electromagnetic and photon-to-pion transition form factors. We report a
striking improvement in the description of all data.Comment: 4 pages, 2 figures. Proceedings Contribution for the 9th
International Workshop on Diffraction in High Energy Physics (Diffraction
2016), Santa Tecla di Acireale, Catania, Italy, September 2-8, 201
The Canonical Structure of the Superstring Action
We consider the canonical structure of the Green-Schwarz superstring in dimensions using the Dirac constraint formalism; it is shown that its
structure is similar to that of the superparticle in and
dimensions. A key feature of this structure is that the primary Fermionic
constraints can be divided into two groups using field-independent projection
operators; if one of these groups is eliminated through use of a Dirac Bracket
(DB) then the second group of primary Fermionic constraints becomes first
class. (This is what also happens with the superparticle action.) These primary
Fermionic first class constraints can be used to find the generator of a local
Fermionic gauge symmetry of the action. We also consider the superstring action
in other dimensions of space-time to see if the Fermionic gauge symmetry can be
made simpler than it is in , and dimensions. With a dimensional target space, we find that such a simplification occurs. We
finally show how in five dimensions there is no first class Fermionic
constraint.Comment: 24 pages, Latex2e; further comments and clarifications adde
Startling Equivalences in the Higgs-Goldstone Sector between Radiative and Lowest-Order Conventional Electroweak Symmetry Breaking
For the Higgs boson mass of GeV expected to arise from radiative
electroweak symmetry breaking, we find the same lowest-order expressions as
would be obtained from conventional electroweak symmetry breaking, given the
same Higgs boson mass, for Higgs-Goldstone sector scattering processes
identified with , , as
well as for Higgs boson decay widths , . The
radiatively broken case, however, leads to an order of magnitude enhancement
over lowest-order conventional symmetry breaking for scattering processes
, , as well as a factor of
enhancement for .Comment: 6 pages, uses ws-ijmpa.cls written in Latex2E. Major revision in text
and conclusions--different enhanced scattering processes found than the
earlier version. To appear in the IJMPA proceedings issue for MRST 2005,
Utica, N
The Effective Potential in Non-Conformal Gauge Theories
By using the renormalization group (RG) equation it has proved possible to
sum logarithmic corrections to quantities that arise due to quantum effects in
field theories. In particular, the effective potential V in the Standard Model
in the limit that there are no massive parameters in the classical action (the
"conformal limit") has been subject to this analysis, as has the effective
potential in a scalar theory with a quartic self coupling and in massless
scalar electrodynamics. Having multiple coupling constants and/or mass
parameters in the initial action complicates this analysis, as then several
mass scales arise. We show how to address this problem by considering the
effective potential in scalar electrodynamics when the scalar field has a tree
level mass term. In addition to summing logarithmic corrections by using the RG
equation, we also consider the consequences of the condition V'(v)=0 where v is
the vacuum expectation value of the scalar. If V is expanded in powers of the
logarithms that arise, then it proves possible to show that either v is zero or
that V is independent of the scalar. (That is, either there is no spontaneous
symmetry breaking or the vacuum expectation value is not determined by
minimizing V as V is "flat".
Treatment of a System with Explicitly Broken Gauge Symmetries
A system in which the free part of the action possesses a gauge symmetry that
is not respected by the interacting part presents problems when quantized. We
illustrate how the Dirac constraint formalism can be used to address this
difficulty by considering an antisymmetric tensor field interacting with a
spinor field.Comment: 10 pages, LaTeX2e, typos correcte
Renormalization Mass Scale and Scheme Dependence in the Perturbative Contribution to Inclusive Semileptonic Decays
We examine the perturbative calculation of the inclusive semi-leptonic decay
rate for the -quark, using mass-independent renormalization. To
finite order of perturbation theory the series for will depend on the
unphysical renormalization scale parameter and on the particular choice
of mass-independent renormalization scheme; these dependencies will only be
removed after summing the series to all orders. In this paper we show that all
explicit -dependence of , through powers of ln, can be
summed by using the renormalization group equation. We then find that this
explicit -dependence can be combined together with the implicit
-dependence of (through powers of both the running coupling
and the running -quark mass ) to yield a -independent
perturbative expansion for in terms of and both
evaluated at a renormalization scheme independent mass scale which is
fixed in terms of either the " mass" of the
quark or its pole mass . At finite order the resulting perturbative
expansion retains a degree of arbitrariness associated with the particular
choice of mass-independent renormalization scheme. We use the coefficients
and of the perturbative expansions of the renormalization group
functions and , associated with and
respectively, to characterize the remaining renormalization scheme
arbitrariness of . We further show that all terms in the expansion of
can be written in terms of the and coefficients and a set
of renormalization scheme independent parameters .Comment: 26 pages, 4 figures, typo correcte
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