More Anomalies from Fractional Branes

In this note we show how the anomalies of both pure and matter coupled N=1,2 supersymmetric gauge theories describing the low energy dynamics of fractional branes on orbifolds can be derived from supergravity.Comment: 11 pages, latex; v2: minor typos fixe

Valles Marineris, Mars: Are pit chains formed by erosion and troughs by tectonism?

The origin of the Valles Marineris remains controversial. Erosional, tectonic, and hybrid processes have been proposed. To clarify these contradictions, the widths and depths of pit chains and troughs were compared and it was found that the features do not form a continuum. Rather, results are consistent with the hypothesis that pit chains formed by surficial collapse and troughs by deeper seated and coherent failure. All pit chains and linear depressions in the Valles Marineris region were classified by inspection into six morphologic categories: pit chains (linear arrays of small pits); floored chains (arrays of pit chains having flat or hummocky floors); scalloped troughs (wider linear depressions with scalloped wall segments); narrow troughs (depressions of intermediate width with straight wall segments); wide troughs (broad, linear depressions); and chaotic troughs (more irregular depressions displaying some channel morphologies). Topographic profiles were drawn across the classified depressions and the erosional width was determined between plateau margins along with the depth from the surrounding plateau level to the deepest part

Anomalies and Tadpoles in Open/Closed String Duality

We discuss the role played by the divergences appearing in the interaction between a fractional D3 brane dressed with an SU(N) gauge field and a stack of N fractional D3 branes on the orbifolds C^2/Z_2 and C^3/(Z_2 x Z_2). In particular we show that the logarithmic divergences in the closed string channel, interpreted as due to twisted massless tadpoles, are mapped, under open/closed string duality, in the logarithmic ones in the open string channel, due to the massless states circulating in the annulus diagram and corresponding to the one-loop divergences that one finds in the gauge theory living in the world volume of the brane. This result provides a quantitative evidence of why the chiral and scale anomalies of the supersymmetric and non conformal gauge theories supported by the world volume of the branes can be inferred from supergravity calculations.Comment: LaTeX, 8 pages. Contribution to the proceedings of the workshop of the RTN Network "The quantum structure of space-time and the geometric nature of fundamental interactions", Copenhagen, September 200

Transverse Lepton Polarization in Polarized W Decays

Calculations of transverse polarization of leptons in the decay $W\rightarrow l\nu$ with polarized $W$'s are presented. Planned accelerators will produce enough $W$'s for observation of the Standard Model contributions to this polarization. One loop corrections to the polarization are given; these are too small to be seen at presently available $W$ sources. The exchange of Majorons will contribute to these polarizations; these may provide limits on the couplings of these particles to leptons.Comment: 8 pages set in RevTex III and 4 uucompressed figures. This revised version studies polarization effects due to the exchange of charged Majoron doublet

On the Gauge/Gravity Correspondence and the Open/Closed String Duality

In this article we review the conditions for the validity of the gauge/gravity correspondence in both supersymmetric and non-supersymmetric string models. We start by reminding what happens in type IIB theory on the orbifolds C^2/Z_2 and C^3/(Z_2 x Z_2), where this correspondence beautifully works. In these cases, by performing a complete stringy calculation of the interaction among D3 branes, it has been shown that the fact that this correspondence works is a consequence of the open/closed duality and of the absence of threshold corrections. Then we review the construction of type 0 theories with their orbifolds and orientifolds having spectra free from both open and closed string tachyons and for such models we study the validity of the gauge/gravity correspondence, concluding that this is not a peculiarity of supersymmetric theories, but it may work also for non-supersymmetric models. Also in these cases, when it works, it is again a consequence of the open/closed string duality and of vanishing threshold corrections.Comment: Invited review article for Int. J. Mod. Phys. A, 95 pages, 2 figures, 3 tables, LaTeX. References and acknowledgements adde

Brane-Inspired Orientifold Field Theories

In this paper we consider the gauge theory living on the world-volume of a stack of N D3-branes of Type 0B/\Omega' I_6(-1)^{F_{L}} and of its orbifolds C^2/Z_2 and C^3/(Z_2 x Z_2). The gauge theories obtained in the three cases are a brane realization of ``orientifold field theories'' having the bosonic sector common with N=4,2,1 super Yang-Mills respectively. In these non-supersymmetric theories, we investigate the possibility of keeping the gauge/gravity correspondence that has revealed itself so successful in the case of supersymmetric theories. In the open string framework we compute the coefficient of the gauge kinetic term showing that the perturbative behaviour of the orientifold field theory can be obtained from the closed string channel in the large N limit, where the theory exhibits Bose-Fermi degeneracy.Comment: 27 pages, LaTe

Can b→sγb\to s\gamma Close the Supersymmetric Higgs Production Window?

We show that the present limit from CLEO on the inclusive decay $b\to s\gamma$ provides strong constraints on the parameters of the charged Higgs sector in two-Higgs-Doublet-Models. Only a slight improvement in the experimental bound will exclude the region in the Supersymmetric Higgs parameter space which is inaccessible to collider searches.Comment: 8 pages plus 3 figures (available by request), latex, ANL-HEP-PR-92-110. Substantial revision to text, results unchange