2,331 research outputs found

### D-Term Inflation: The Good, the Bad and the Ugly

An inflationary stage dominated by a D-term avoids the slow-roll problem of
inflation in supergravity and can naturally emerge in theories with a
non-anomalous or anomalous U(1) gauge symmetry. In this talk different aspects
of D-term inflation are discussed.Comment: 6 pages, LaTeX file, uses sprocl.sty. Based on the invited plenary
talk given at the COSMO97 Conference, Ambleside, England, September 15-19
1997 and on the talk given at the Phenomenological Aspects of Superstring
Theories (PAST97) Conference, ICTP Trieste, Italy, October 2-4 1997. To
appear in the Proceeding

### The Nature of Corporate Governance: The Significance of National Cultural Identity

This book presents a thoughtful inquiry into the nature and rationale of corporate governance. The authors address fundamental questions including; What is the balance between ownership and control?; For whose interests should the company be run?; What is the institutional balance between shareholders, directors and other potential stakeholders, including the economy

### Multigraviton Scattering in the Matrix Model

We consider scattering processes in the matrix model with three incoming and
three outgoing gravitons. We find a discrepancy between the amplitude
calculated from the matrix model and the supergravity prediction. Possible
sources for this discrepancy are discussed.Comment: 11 pages, latex, references adde

### On Witten's Instability and Winding Tachyons

We investigate, from a spacetime perspective, some aspects of Horowitz's
recent conjecture that black strings may catalyze the decay of Kaluza-Klein
spacetimes into a bubble of nothing. We identify classical configurations that
interpolate between flat space and the bubble, and discuss the energetics of
the transition. We investigate the effects of winding tachyons on the size and
shape of the barrier and find no evidence at large compactification radius that
tachyons enhance the tunneling rate. For the interesting radii, of order the
string scale, the question is difficult to answer due to the failure of the
$\alpha^\prime$ expansion.Comment: 15 pages, 2 figures, Late

### Renormalization in General Gauge Mediation

We revisit General Gauge Mediation (GGM) in light of the supersymmetric
(linear) sigma model by utilizing the current superfield. The current
superfield in the GGM is identified with supersymmetric extension of the vector
symmetry current of the sigma model while spontaneous breakdown of
supersymmetry in the GGM corresponds to soft breakdown of the axial vector
symmetry of the sigma model. We first derive the current superfield from the
supersymmetric linear sigma model and then compute 2-point functions of the
current superfield using the (anti-)commutation relations of the messenger
component fields. After the global symmetry are weakly gauged, the 2-point
functions of the current superfield are identified with a part of the 2-point
functions of the associated vector superfield. We renormalize them by
dimensional regularization and show that physical gaugino and sfermion masses
of the MSSM are expressed in terms of the wavefunction renormalization
constants of the component fields of the vector superfield.Comment: 25 pages, 12 figure

### Implications of Low Energy Supersymmetry Breaking at the Tevatron

The signatures for low energy supersymmetry breaking at the Tevatron are
investigated. It is natural that the lightest standard model superpartner is an
electroweak neutralino, which decays to an essentially massless Goldstino and
photon, possibly within the detector. In the simplest models of gauge-mediated
supersymmetry breaking, the production of right-handed sleptons, neutralinos,
and charginos leads to a pair of hard photons accompanied by leptons and/or
jets with missing transverse energy. The relatively hard leptons and softer
photons of the single e^+e^- \gamma \gamma + \EmissT event observed by CDF
implies this event is best interpreted as arising from left-handed slepton pair
production. In this case the rates for l^{\pm} \gamma \gamma + \EmissT and
\gamma \gamma + \EmissT are comparable to that for l^+l^- \gamma \gamma +
\EmissT.Comment: 18 pages, Latex, tables correcte

### Symmetric Points in the Landscape as Cosmological Attractors

In the landscape, if there is to be any prospect of scientific prediction, it
is crucial that there be states which are distinguished in some way. The
obvious candidates are states which exhibit symmetries. Here we focus on states
which exhibit discrete symmetries. Such states are rare, but one can speculate
that they are cosmological attractors. We investigate the problem in model
landscapes and cosmologies which capture some of the features of candidate flux
landscapes. In non-supersymmetric theories we find no evidence that such states
might be cosmologically favored. In supersymmetric theories, simple arguments
suggest that states which exhibit $R$ symmetries might be. Our considerations
lead us to raise questions about some popular models of eternal inflation.Comment: 27 pages, latex, minor typo correcte

### Remarks on the Racetrack Scheme

There are only a small number of ideas for stabilizing the moduli of string
theory. One of the most appealing of these is the racetrack mechanism, in which
a delicate interplay between two strongly interacting gauge groups fixes the
value of the coupling constant. In this note, we explore this scenario. We find
that quite generally, some number of discrete tunings are required in order
that the mechanism yield a small gauge coupling. Even then, there is no sense
in which a weak coupling approximation is valid. On the other hand, certain
holomorphic quantities can be computed, so such a scheme is in principle
predictive. Searching for models which realize this mechanism is thus of great
interest. We also remark on cosmology in these schemes.Comment: 20 pp, latex, discussion of calculability modifie

### Electroweak Symmetry Breaking due to Confinement

Within the framework of gauge mediated supersymmetry breaking, we consider an
electroweak symmetry breaking pattern in which there is no conventional $\mu$
term. The pattern is made appealing through realizing it as low energy
effective description of a supersymmetric Yang-Mills theory which is of
confinement. Phenomenological implications are discussed.Comment: 8 pages, revtex, no figure, the discussion on effective
superpotential refine

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