2,004 research outputs found
N=2 SYM RG Scale as Modulus for WDVV Equations
We derive a new set of WDVV equations for N=2 SYM in which the
renormalization scale is identified with the distinguished modulus
which naturally arises in topological field theories.Comment: 6 pages, LaTe
Branched Coverings and Interacting Matrix Strings in Two Dimensions
We construct the lattice gauge theory of the group G_N, the semidirect
product of the permutation group S_N with U(1)^N, on an arbitrary Riemann
surface. This theory describes the branched coverings of a two-dimensional
target surface by strings carrying a U(1) gauge field on the world sheet. These
are the non-supersymmetric Matrix Strings that arise in the unitary gauge
quantization of a generalized two-dimensional Yang-Mills theory. By classifying
the irreducible representations of G_N, we give the most general formulation of
the lattice gauge theory of G_N, which includes arbitrary branching points on
the world sheet and describes the splitting and joining of strings.Comment: LaTeX2e, 25 pages, 4 figure
Algebraic-geometrical formulation of two-dimensional quantum gravity
We find a volume form on moduli space of double punctured Riemann surfaces
whose integral satisfies the Painlev\'e I recursion relations of the genus
expansion of the specific heat of 2D gravity. This allows us to express the
asymptotic expansion of the specific heat as an integral on an infinite
dimensional moduli space in the spirit of Friedan-Shenker approach. We outline
a conjectural derivation of such recursion relations using the
Duistermaat-Heckman theorem.Comment: 10 pages, Latex fil
A Representation of Symmetry Generators for the Type IIB Superstring on a Plane Wave in the U(4) Formalism
We calculate the symmetry currents for the type IIB superstring on a
maximally supersymmetric plane wave background using the N=(2,2)
superconformally covariant U(4) formulation developed by Berkovits, Maldacena
and Maoz. An explicit realization of the U(4) generators together with 16
fermionic generators is obtained in terms of the N=(2,2) worldsheet fields.
Because the action is no longer quadratic, we use a light-cone version to
display the currents in terms of the covariant worldsheet variables.Comment: 9 pages, harvmac, Corrected some typographical errors, Added
reference
Nonperturbative Relations in N=2 SUSY Yang-Mills and WDVV equation
We find the nonperturbative relation between , the prepotential and the
vevs in supersymmetric Yang-Mills theories with
gauge group . Nonlinear differential equations for including
the Witten -- Dijkgraaf -- Verlinde -- Verlinde equation are obtained. This
indicates that SYM theories are essentially topological field theories
and that should be seen as low-energy limit of some topological string theory.
Furthermore, we construct relevant modular invariant quantities, derive
canonical relations between the periods and investigate the structure of the
beta function by giving its explicit form in the moduli coordinates. In doing
this we discuss the uniformization problem for the quantum moduli space. The
method we propose can be generalized to supersymmetric Yang-Mills
theories with higher rank gauge groups.Comment: 12 pages, LaTex. Expanded version. New results, corrections,
references and acknowledgements adde
Bronchoalveolar lavage fluid cytological findings in healthy Amiata donkeys
Background: The approach to respiratory diseases in donkeys is similar to that for horses; nevertheless, Bronchoalveolar lavage fluid (BALF) and tracheal wash cytology in this species have been described only a few times in the literature. Aim: To describe BALF cytological findings in a cohort of 24 healthy Amiata donkeys. Methods: Bronchoalveolar lavage (BAL) was carried out via standing sedation with a large animal where the BAL catheter passed blindly through the nasal passage into the trachea. Results: The total nucleated cell count of the BALF was found similar to that already described in healthy horses and donkeys. No differences in the differential count were observed according to age and sex. A decreased macrophage percentage and an increased eosinophil percentage were observed in our donkey population when compared to the existing reference range for horses. Conclusion: The reference intervals for BAL cytology in donkeys may be significantly different for those referred for horses
Matrix strings from generalized Yang-Mills theory on arbitrary Riemann surfaces
We quantize pure 2d Yang-Mills theory on an arbitrary Riemann surface in the
gauge where the field strength is diagonal. Twisted sectors originate, as in
Matrix string theory, from permutations of the eigenvalues around homotopically
non-trivial loops. These sectors, that must be discarded in the usual
quantization due to divergences occurring when two eigenvalues coincide, can be
consistently kept if one modifies the action by introducing a coupling of the
field strength to the space-time curvature. This leads to a generalized
Yang-Mills theory whose action reduces to the usual one in the limit of zero
curvature. After integrating over the non-diagonal components of the gauge
fields, the theory becomes a free string theory (sum over unbranched coverings)
with a U(1) gauge theory on the world-sheet. This is shown to be equivalent to
a lattice theory with a gauge group which is the semi-direct product of S_N and
U(1)^N. By using well known results on the statistics of coverings, the
partition function on arbitrary Riemann surfaces and the kernel functions on
surfaces with boundaries are calculated. Extensions to include branch points
and non-abelian groups on the world-sheet are briefly commented upon.Comment: Latex2e, 29 pages, 2 .eps figure
Matrix string states in pure 2d Yang Mills theories
We quantize pure 2d Yang-Mills theory on a torus in the gauge where the field
strength is diagonal. Because of the topological obstructions to a global
smooth diagonalization, we find string-like states in the spectrum similar to
the ones introduced by various authors in Matrix string theory. We write
explicitly the partition function, which generalizes the one already known in
the literature, and we discuss the role of these states in preserving modular
invariance. Some speculations are presented about the interpretation of 2d
Yang-Mills theory as a Matrix string theory.Comment: Latex file of 38 pages plus 6 eps figures. A note and few references
added, figures improve
Haematological and biochemical findings in pregnant, postfoaling and lactating jennies
The aims of this study were to: 1) verify if significant changes occur in hematological and biochemical parameters in jennies during the last two months of pregnancy and the first two months of lactation, and 2) determine any differences with equine species.
Materials and methods. Hematological and biochemical parameters were evaluated in jennies every 15 days during late pregnancy, parturition, and early lactation. The Kolmogorov-Smirnov test, ANOVA for repeated measurements and Tukey’s multiple comparison test as post hoc were applied. The significance level was set at p<0.05.
Results. Statistical analysis showed differences related to time for RBC and HCT, WBC, PLT, total proteins (TP), blood urea, triglycerides and total cholesterol concentrations, AST, GGT, CK activities, sodium (Na) and potassium (K).
Discussion and conclusions. RBC and HCT were higher in late pregnancy than at foaling and during lactation. The relative anaemia might be due to increased water ingestion due to fluid losses. The WBC count was higher at foaling than during late pregnancy and lactation. This could be related to the release of cortisol and catecholamine during delivery. The PLT trend showed lower values from delivery to the first two months of lactation compared to late gestation. Blood urea increased near parturition, and then remained constant during delivery and lactation, which might be due to the high-energy demand at the beginning of lactation. Triglycerides and total cholesterol showed a decrease from delivery through the lactation period. Thus jennies seem to have a similar metabolism of fats to ponies and draft horse mares, characterized by a greater fat content and mobilization than light breed horses. AST activity decreased at parturition and early lactation, probably due to a predominance of anabolic over catabolic processes during pregnancy. GGT activity was lower at delivery and during lactation than at late gestation. This could be due to a physiological load on the liver in the perinatal period. GGT activity was always higher than in mares, but within the normal range for adult donkeys. CK decreased near delivery, then was constant from parturition through the first two months of lactation. Na decreased during lactation, probably due to an increased renal retention mediated by aldosterone release during pregnancy. K showed the same trend as Na, and concentrations are in line with the species. The higher K during pregnancy may be due to reabsorption by the gut. TP decreased more during the post-partum period and lactation than in the gestational period
RG Flow Irreversibility, C-Theorem and Topological Nature of 4D N=2 SYM
We determine the exact beta function and a RG flow Lyapunov function for N=2
SYM with gauge group SU(n). It turns out that the classical discriminants of
the Seiberg-Witten curves determine the RG potential. The radial
irreversibility of the RG flow in the SU(2) case and the non-perturbative
identity relating the -modulus and the superconformal anomaly, indicate the
existence of a four dimensional analogue of the c-theorem for N=2 SYM which we
formulate for the full SU(n) theory. Our investigation provides further
evidence of the essentially topological nature of the theory.Comment: 9 pages, LaTeX file. Discussion on WDVV and integrability. References
added. Version published in PR
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