A Comparison of Supersymmetry Breaking and Mediation Mechanisms

We give a unified treatment of different models of supersymmetry breaking and mediation from a four dimensional effective field theory standpoint. In particular a comparison between GMSB and various gravity mediated versions of SUSY breaking shows that, once the former is embedded within a SUGRA framework, there is no particular advantage to that mechanism from the point of view of FCNC suppression. We point out the difficulties of all these scenarios - in particular the cosmological modulus problem. We end with a discussion of possible string theory realizations.Comment: Added clarifications and references, 20 page

Western propaganda models reconsidered : the "Catherine Whell" of censorship circumvention in developing world internal conflicts

This study is a deep-text analysis of military censorship applied to the national press in the Sri Lankan conflict. We examine press coverage of two Sri Lankan military operations, namely Operation Jayasikurui (1997) and the Capture of Elephant Pass (2000), to identify patterns of signification that help us construct a novel theory of conflict reporting under censorship within the context of ethnic, intrastate conflict. Our study shows that Sri Lankan newspapers, while abiding by censorship regulations, contradictorily also manoeuvred around these regulations as if censorship did not exist. Noteworthy were the censorship circumvention techniques that were used. For example, journalists taught readers how to &lsquo;read&rsquo; blank space. They used commentary to educate readers how to read the straight news. They used conflict frames to overcome bias towards official viewpoints. They used multi-source confirmation to avoid pre-dominance of official views. They used respectful words rather than demonised opponents. Great attentionwas paid to victims of the conflict, destruction of life and property, and civil society. Our findings do not accord well with previous theoretical models of the media role in society and of press censorship under conflict. The Sri Lankan press is highly intertwined within its cultural context and follows its own value system. We propose the &lsquo;Catherine Wheel Model of Censorship Circumvention&rsquo; about press behaviour in times of internal conflict. Our model attempts to explain internal conflict within the developing world context in which the press system is based deeply in culture and is more accustomed to circumventing censorship than obeying it.<br /

Constraints on LVS Compactifications of IIB String Theory

We argue that once all theoretical and phenomenological constraints are imposed on the different versions of the Large Volume Scenario (LVS) compactifications of type IIB string theory, one particular version is favored. This is essentially a sequestered one in which the soft terms are generated by Weyl anomaly and RG running effects. We also show that arguments questioning sequestering in LVS models are not relevant in this case.Comment: 14 pages, additional discussion of D7 brane case and mSUGRA, reference adde

Randall-Sundrum Brane Tensions

We show that the singular sources in the energy-momentum tensor for the Randall-Sundrum brane world, viewed as a solution of type IIB supergravity, are composed of two elements. One of these is a D3-brane source with tension opposite in sign to the RS tension in five dimensions; the other arises from patching two regions of flat ten-dimensional spacetime. This resolves an apparent discrepancy between supersymmetry and the sign and magnitude of the RS tension.Comment: Latex, 21 pages, 2 figure

Gaugino Anomaly Mediated SUSY Breaking: phenomenology and prospects for the LHC

We examine the supersymmetry phenomenology of a novel scenario of supersymmetry (SUSY) breaking which we call Gaugino Anomaly Mediation, or inoAMSB. This is suggested by recent work on the phenomenology of flux compactified type IIB string theory. The essential features of this scenario are that the gaugino masses are of the anomaly-mediated SUSY breaking (AMSB) form, while scalar and trilinear soft SUSY breaking terms are highly suppressed. Renormalization group effects yield an allowable sparticle mass spectrum, while at the same time avoiding charged LSPs; the latter are common in models with negligible soft scalar masses, such as no-scale or gaugino mediation models. Since scalar and trilinear soft terms are highly suppressed, the SUSY induced flavor and CP-violating processes are also suppressed. The lightest SUSY particle is the neutral wino, while the heaviest is the gluino. In this model, there should be a strong multi-jet +etmiss signal from squark pair production at the LHC. We find a 100 fb^{-1} reach of LHC out to m_{3/2}\sim 118 TeV, corresponding to a gluino mass of \sim 2.6 TeV. A double mass edge from the opposite-sign/same flavor dilepton invariant mass distribution should be visible at LHC; this, along with the presence of short-- but visible-- highly ionizing tracks from quasi-stable charginos, should provide a smoking gun signature for inoAMSB.Comment: 30 pages including 14 .eps figure

Consequence of Hawking radiation from 2d dilaton black holes

We investigate the CGHS model through numerical calculation. The behavior of the mass function, which we introduced in our previous work as a ``local mass'', is examined. We found that the mass function takes negative values, which means that the amount of Hawking radiation becomes greater than the initial mass of the black hole as in the case of the RST model.Comment: 17pages, 5 figures (three of them are attached, the other 2 figures are available on request. Some mistakes including typographic errors have been correcte

Dual D-Brane Actions

Dual super Dp-brane actions are constructed by carrying out a duality transformation of the world-volume U(1) gauge field. The resulting world-volume actions, which contain a (p - 2)-form gauge field, are shown to have the expected properties. Specifically, the D1-brane and D3-brane transform in ways that can be understood on the basis of the SL(2, Z) duality of type IIB superstring theory. Also, the D2-brane and the D4-brane transform in ways that are expected on the basis of the relationship between type IIA superstring theory and 11d M theory. For example, the dual D4-brane action is shown to coincide with the double-dimensional reduction of the recently constructed M5-brane action. The implications for gauge-fixed D-brane actions are discussed briefly.Comment: 18 pages, latex, no figures; references adde

Quantum Black Hole Evaporation

We investigate a recently proposed model for a full quantum description of two-dimensional black hole evaporation, in which a reflecting boundary condition is imposed in the strong coupling region. It is shown that in this model each initial state is mapped to a well-defined asymptotic out-state, provided one performs a certain projection in the gravitational zero mode sector. We find that for an incoming localized energy pulse, the corresponding out-going state contains approximately thermal radiation, in accordance with semi-classical predictions. In addition, our model allows for certain acausal strong coupling effects near the singularity, that give rise to corrections to the Hawking spectrum and restore the coherence of the out-state. To an asymptotic observer these corrections appear to originate from behind the receding apparent horizon and start to influence the out-going state long before the black hole has emitted most of its mass. Finally, by putting the system in a finite box, we are able to derive some algebraic properties of the scattering matrix and prove that the final state contains all initial information.Comment: 37 pages (figs 2 and 3 included as uuencoded compressed tar file), Latex, needs epsf.tex, PUPT-1395, IASSNS-HEP-93/25 (revised version has minor corrections, one reference added

M Theory As A Matrix Model: A Conjecture

We suggest and motivate a precise equivalence between uncompactified eleven dimensional M-theory and the N = infinity limit of the supersymmetric matrix quantum mechanics describing D0-branes. The evidence for the conjecture consists of several correspondences between the two theories. As a consequence of supersymmetry the simple matrix model is rich enough to describe the properties of the entire Fock space of massless well separated particles of the supergravity theory. In one particular kinematic situation the leading large distance interaction of these particles is exactly described by supergravity . The model appears to be a nonperturbative realization of the holographic principle. The membrane states required by M-theory are contained as excitations of the matrix model. The membrane world volume is a noncommutative geometry embedded in a noncommutative spacetime.Comment: Typo and tex error corrected. 41 pages, harvma