362 research outputs found
Superconformal Primary Fields on a Graded Riemann Sphere
Primary superfields for a two dimensional Euclidean superconformal field
theory are constructed as sections of a sheaf over a graded Riemann sphere. The
construction is then applied to the N=3 Neveu-Schwarz case. Various quantities
in the N=3 theory are calculated and discussed, such as formal elements of the
super-Mobius group, and the two-point function.Comment: LaTeX2e, 23 pages; fixed typos, sorted references, modified
definition of primary superfield on page
SYM, Chern-Simons, Wess-Zumino Couplings and their higher derivative corrections in IIA Superstring theory
We find the entire form of the amplitude of two fermion strings (with
different chirality), a massless scalar field and one closed string
Ramond-Ramond (RR) in IIA superstring theory which is different from its IIB
one. We make use of a very particular gauge fixing and explore several new
couplings in IIA. All infinite - channel scalar poles and - channel
fermion poles are also constructed. We find new form of higher derivative
corrections to two fermion two scalar couplings and show that the first simple
channel scalar pole for case can be obtained by having new
higher derivative corrections to SYM couplings at third order of . We
find that the general structure and the coefficients of higher derivative
corrections to two fermion two scalar couplings are completely different from
the derived higher derivative corrections of type IIB.Comment: 29 pages, no figure,Latex file,published version in EPJ
The N=4 string is the same as the N=2 string
We redo the quantization of the N=4 string, taking into account the
reducibility of the constraints. The result is equivalent to the N=2 string,
with critical dimension D=4 and signature (++--). The N=4 formulation has
several advantages: the sigma-model field equations are implied classically,
rather than by quantum/beta-function calculations; self-duality/chirality is
one of the super-Virasoro constraints; SO(2,2) covariance is manifest. This
reveals that the theory includes fermions, and is apparently spacetime
supersymmetric.Comment: 7 pg (uuencoded dvi file; otherwise same as original
Regge behavior saves string theory from causality violations
Higher-derivative corrections to the Einstein-Hilbert action are present in bosonic string theory leading to the potential causality violations recently pointed out by Camanho et al. [1]. We analyze in detail this question by considering high-energy string-brane collisions at impact parameters b ≤ l s (the string-length parameter) with l s ≫ R p (the characteristic scale of the D p -brane geometry). If we keep only the contribution of the massless states causality is violated for a set of initial states whose polarization is suitably chosen with respect to the impact parameter vector. Such violations are instead neatly avoided when the full structure of string theory — and in particular its Regge behavior — is taken into account
The N=2(4) string is self-dual N=4 Yang-Mills
N=2 string amplitudes, when required to have the Lorentz covariance of the
equivalent N=4 string, describe a self-dual form of N=4 super Yang-Mills in 2+2
dimensions. Spin-independent couplings and the ghost nature of SO(2,2)
spacetime make it a topological-like theory with vanishing loop corrections.Comment: 7 pg., ITP-SB-92-24 (uuencoded dvi file; otherwise same as original
A Hierarchy of Superstrings
We construct a hierarchy of supersymmetric string theories by showing that
the general N-extended superstrings may be viewed as a special class of the
(N+1)-extended superstrings. As a side result, we find a twisted (N+2)
superconformal algebra realized in the N-extended string.Comment: 9 pages, LaTex, NBI-HE-94-2
The BRST Operator for the Large Superconformal Algebra
We review the detailed structure of the large superconformal algebra,
and construct its BRST operator which constitutes the main object for analyzing
strings. We then derive the general condition for the nilpotency of the
BRST operator and show that there exists a line of critical string
theories.Comment: Latex file, 16 pages, NBI-HE-94-1
Green-Schwarz Formulation of Self-Dual Superstring
The self-dual superstring has been described previously in a
Neveu-Schwarz-Ramond formulation with local N=2 or 4 world-sheet supersymmetry.
We present a Green-Schwarz-type formulation, with manifest spacetime
supersymmetry.Comment: 11 pg., (uuencoded dvi file) ITP-SB-92-5
Semileptonic Hyperon Decays on the Lattice: an Exploratory Study
We present preliminary results of an exploratory lattice study of the vector
form factor relevant for the semileptonic hyperon decay
. This study is based on the same method used for the
extraction of for the decay . The main purpose
of this study is to test the method for hyperon form factors in order to
estimate the precision that can be reached and the importance of SU(3)-breaking
effects.Comment: 3 pages, 5 figures, talk presented at Lattice2004(weak), Fermilab,
Batavia, Illinois, 21-26 June 200
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