90 research outputs found
Geometrical properties of Riemannian superspaces, observables and physical states
Classical and quantum aspects of physical systems that can be described by
Riemannian non degenerate superspaces are analyzed from the topological and
geometrical points of view. For the N=1 case the simplest supermetric
introduced in [Physics Letters B \textbf{661}, (2008),186] have the correct
number of degrees of freedom for the fermion fields and the super-momentum
fulfil the mass shell condition, in sharp contrast with other cases in the
literature where the supermetric is degenerate. This fact leads a deviation of
the 4-impulse (e.g. mass constraint) that can be mechanically interpreted as a
modification of the Newton's law. Quantum aspects of the physical states and
the basic states and the projection relation between them, are completely
described due the introduction of a new Majorana-Weyl representation of the
generators of the underlying group manifold. A new oscillatory fermionic effect
in the part of the vaccum solution involving the chiral and antichiral
components of this Majorana bispinor is explicitly shown.Comment: 16 pags. 3 figures. To Anna Grigorievna Kartavenko and Academic
Professor Alexei Norianovich Sissakian, in memoria
Superspace formulations of the (super)twistor string
The superspace formulation of the worldvolume action of twistor string models
is considered. It is shown that for the Berkovits-Siegel closed twistor string
such a formulation is provided by a N=4 twistor-like action of the tensionless
superstring. A similar inverse twistor transform of the open twistor string
model (Berkovits model) results in a dynamical system containing two copies of
the D=4, N=4 superspace coordinate functions, one left-moving and one
right-moving, that are glued by the boundary conditions.
We also discuss possible candidates for a tensionful superstring action
leading to the twistor string in the tensionless limit as well as
multidimensional counterparts of twistor strings in the framework of both
`standard' superspace and superspace enlarged by tensorial coordinates
(tensorial superspaces), which constitute a natural framework for massless
higher spin theories.Comment: Rev Tex, 13 pages, no figure
Supertwistors, massive superparticles and k-symmetry
We consider a D=4 two-twistor lagrangian for a massive particle that
incorporates the mass-shell condition in an algebraic way, and extend it to a
two-supertwistor model with N=2 supersymmetry and central charge identified
with the mass. In the purely supertwistorial picture the two D=4 supertwistors
are coupled through a Wess-Zumino term in their fermionic sector. We
demonstrate how the kappa-gauge symmetry appears in the purely supertwistorial
formulation and reduces by half the fermionic degrees of freedom of the two
supertwistors; a formulation of the model in terms of kappa-invariant degrees
of freedom is also obtained. We show that the kappa-invariant supertwistor
coordinates can be obtained by dimensional (D=6 -> D=4) reduction from a D=6
supertwistor. We derive as well by 6 -> 4 reduction the N=2, D=4 massive
superparticle model with Wess-Zumino term introduced in 1982. Finally, we
comment on general superparticle models constructed with more than two
supertwistors.Comment: Shorter version, to appear in JHEP, with emphasis on the D=6
quaternionic structur
Vacuum instability in external fields
We study particles creation in arbitrary space-time dimensions by external
electric fields, in particular, by fields, which are acting for a finite time.
The time and dimensional analysis of the vacuum instability is presented. It is
shown that the distributions of particles created by quasiconstant electric
fields can be written in a form which has a thermal character and seems to be
universal. Its application, for example, to the particles creation in external
constant gravitational field reproduces the Hawking temperature exactly.Comment: 36 pages, LaTe
Three-loop universal anomalous dimension of the Wilson operators in N=4 SUSY Yang-Mills model
We present results for the three-loop universal anomalous dimension of Wilson
twist-2 operators in the N=4 Supersymmetric Yang-Mills model. These results are
obtained by extracting the most complicated contributions from the three loop
non-singlet anomalous dimensions in QCD which were calculated recently. Their
singularities at j=1 agree with the predictions obtained from the BFKL equation
for N=4 SYM in the next-to-leading order. The asymptotics of universal
anomalous dimension at large j is in an agreement with the expectations based
on an interpolation between weak and strong coupling regimes in the framework
of the AdS/CFT correspondence.Comment: LaTeX file, 13 pages, no figures. Some corrections, additional
remarks and references. In the last version the analysis of anomalous
dimension at j -> 2 was improve
Two-loop scalar self-energies in a general renormalizable theory at leading order in gauge couplings
I present results for the two-loop self-energy functions for scalars in a
general renormalizable field theory, using mass-independent renormalization
schemes based on dimensional regularization and dimensional reduction. The
results are given in terms of a minimal set of loop-integral basis functions,
which are readily evaluated numerically by computers. This paper contains the
contributions corresponding to the Feynman diagrams with zero or one vector
propagator lines. These are the ones needed to obtain the pole masses of the
neutral and charged Higgs scalar bosons in supersymmetry, neglecting only the
purely electroweak parts at two-loop order. A subsequent paper will present the
results for the remaining diagrams, which involve two or more vector lines.Comment: 26 pages, 4 figures, revtex4, axodraw.sty. Version 2: sentence after
eq. (A.13) corrected, references added. Version 3: typos in eqs. (5.17),
(5.20), (5.21), (5.32) are corrected. Also, the MSbar versions of eqs. (5.32)
and (5.33) are now include
Superparticle Models with Tensorial Central Charges
A generalization of the Ferber-Shirafuji formulation of superparticle
mechanics is considered. The generalized model describes the dynamics of a
superparticle in a superspace extended by tensorial central charge coordinates
and commuting twistor-like spinor variables. The D=4 model contains a
continuous real parameter and at a=0 reduces to the SU(2,2|1)
supertwistor Ferber-Shirafuji model, while at a=1 one gets an OSp(1|8)
supertwistor model of ref. [1] (hep-th/9811022) which describes BPS states with
all but one unbroken target space supersymmetries. When 0<a<1 the model admits
an OSp(2|8) supertwistor description, and when a>1 the supertwistor group
becomes OSp(1,1|8). We quantize the model and find that its quantum spectrum
consists of massless states of an arbitrary (half)integer helicity. The
independent discrete central charge coordinate describes the helicity spectrum.
We also outline the generalization of the a=1 model to higher space-time
dimensions and demonstrate that in D=3,4,6 and 10, where the quantum states are
massless, the extra degrees of freedom (with respect to those of the standard
superparticle) parametrize compact manifolds. These compact manifolds can be
associated with higher-dimensional helicity states. In particular, in D=10 the
additional ``helicity'' manifold is isomorphic to the seven-sphere.Comment: 32 pages, LATEX, no figure
Factorization of integrals, defining the beta-function, into integrals of total derivatives in N=1 SQED, regularized by higher derivatives
Some calculations in supersymmetric theories, made with the higher derivative
regularization, show that the beta-function is given by integrals of total
derivatives. This is qualitatively explained for the N=1 supersymmetric
electrodynamics in all orders.Comment: 14 page
The effects of introducing the Amazonian squirrel monkey on the behavior of the northeast marmoset
Non-compact Groups, Coherent States, Relativistic Wave Equations and the Harmonic Oscillator II: Physical and Geometrical Considerations
The physical meaning of the particularly simple non-degenerate supermetric,
introduced in the previous part by the authors, is elucidated and the possible
connection with processes of topological origin in high energy physics is
analyzed and discussed. New possible mechanism of the localization of the
fields in a particular sector of the supermanifold is proposed and the
similarity and differences with a 5-dimensional warped model are shown. The
relation with gauge theories of supergravity based in the group is
explicitly given and the possible original action is presented. We also show
that in this non-degenerate super-model the physic states, in contrast with the
basic states, are observables and can be interpreted as tomographic projections
or generalized representations of operators belonging to the metaplectic group
. The advantage of geometrical formulations based on non-degenerate
super-manifolds over degenerate ones is pointed out and the description and the
analysis of some interesting aspects of the simplest Riemannian superspaces are
presented from the point of view of the possible vacuum solutions.Comment: Stile of the text improved in Journa
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