726 research outputs found
Boundaries and Defects of N=4 SYM with 4 Supercharges, Part II: Brane Constructions and 3d N=2 Field Theories
We study the vacuum moduli spaces of 3d N=2 supersymmetric quantum field
theories by applying the formalism developed in our previous paper
arXiv:1404.5527. The 3d theories can be realized by branes in type IIB string
theory, which in a decoupling limit reduce to 4d N=4 super-Yang-Mills theory on
an interval with BPS defects inserted. The moduli space of a given 3d theory is
obtained by solving a generalization of Nahm's equations with appropriate
boundary/junction conditions, along with help from the S-duality of type IIB
string theory. Our classical computations reproduce many known results about
the quantum-corrected moduli spaces of 3d theories, e.g. U(N_c) theories with
N_f flavors with mass and FI parameters turned on. In particular, our methods
give first-principles derivations of several results in the literature,
including the s-rule, quantum splitting of classical Coulomb branches, the
lifting of the Coulomb branch by non-Abelian instantons, quantum merging of
Coulomb and Higgs branches, and phase transitions from re-ordering 5-branes.Comment: 83 pages, 27 figure
Boundaries and Defects of N=4 SYM with 4 Supercharges, Part I: Boundary/Junction Conditions
We consider supersymmetric Yang Mills theory on a space with
supersymmetry preserving boundary conditions. The boundaries preserving half of
the 16 supercharges were analyzed and classified in an earlier work by Gaiotto
and Witten. We extend that analysis to the case with fewer supersymmetries,
concentrating mainly on the case preserving one quarter. We develop tools
necessary to explicitly construct boundary conditions which can be viewed as
taking the zero slope limit of a system of D3 branes intersecting and ending on
a collection of NS5 and D5 branes oriented to preserve the appropriate number
of supersymmetries. We analyze how these boundary conditions constrain the bulk
degrees of freedom and enumerate the unconstrained degrees of freedom from the
boundary/defect field theory point of view. The key ingredients used in the
analysis are a generalized version of Nahm's equations and the explicit
boundary/interface conditions for the NS5-like and D5-like impurities and
boundaries, which we construct and describe in detail. Some bulk degrees of
freedom suggested by the naive brane diagram considerations are lifted.Comment: 75 pages, 21 figure
Moduli Stabilization and Supersymmetry Breaking in Deflected Mirage Mediation
We present a model of supersymmetry breaking in which the contributions from
gravity/modulus, anomaly, and gauge mediation are all comparable. We term this
scenario "deflected mirage mediation," which is a generalization of the
KKLT-motivated mirage mediation scenario to include gauge mediated
contributions. These contributions deflect the gaugino mass unification scale
and alter the pattern of soft parameters at low energies. In some cases, this
results in a gluino LSP and light stops; in other regions of parameter space,
the LSP can be a well-tempered neutralino. We demonstrate explicitly that
competitive gauge-mediated terms can naturally appear within phenomenological
models based on the KKLT setup by addressing the stabilization of the gauge
singlet field which is responsible for the masses of the messenger fields. For
viable stabilization mechanisms, the relation between the gauge and anomaly
contributions is identical in most cases to that of deflected anomaly
mediation, despite the presence of the Kahler modulus. Turning to TeV scale
phenomenology, we analyze the renormalization group evolution of the
supersymmetry breaking terms and the resulting low energy mass spectra. The
approach sets the stage for studies of such mixed scenarios of supersymmetry
breaking at the LHC.Comment: 33 pages, 8 figures. Published version in Journal of High Energy
Physic
Mesons and Flavor on the Conifold
We explore the addition of fundamental matter to the Klebanov-Witten field
theory. We add probe D7-branes to the theory obtained from placing
D3-branes at the tip of the conifold and compute the meson spectrum for the
scalar mesons. In the UV limit of massless quarks we find the exact dimensions
of the associated operators, which exhibit a simple scaling in the large-charge
limit. For the case of massive quarks we compute the spectrum of scalar mesons
numerically.Comment: 19 pages, 3 figures, v2: typos fixe
Merger & Acquisition and Capital Expenditure in Health Care: Information Gleaned From Stock Price Variation
Investment, especially through merger and acquisition (M&A), is a leading topic of concern among health care managers. In addition, the implications of this activity for organization and market concentration are of great interest to policy makers. Using a sample of 2256 firm-year observations in the health care industry during the period from 1985 to 2011, this article provides novel evidence that managers learn from financial markets in making capital expenditure (CAPEX) and M&A investment decisions. Within the industry, managers in the Drugs subsector are most likely to do so, whereas managers in the Medical Equipment and Supplies are least likely to do so. We find informative stock prices improve firm financial performance. This article highlights the importance of financial markets for real economic activity in the health care industry
Deflected Mirage Mediation: A Phenomenological Framework for Generalized Supersymmetry Breaking
We present a general phenomenological framework for dialing between gravity mediation, gauge mediation, and anomaly mediation. The approach is motivated from recent developments in moduli stabilization, which suggest that gravity mediated terms can be effectively loop suppressed and thus comparable to gauge and anomaly mediated terms. The gauginos exhibit a mirage unification behavior at a “deflected” scale, and gluinos are often the lightest colored sparticles. The approach provides a rich setting in which to explore generalized supersymmetry breaking at the CERN Large Hadron Collider
Fractional D1-Branes at Finite Temperature
The supergravity dual of regular and fractional D1-branes on the cone
over the Einstein manifold has a naked singularity in the infrared.
The supergravity dual of regular and fractional D3-branes on the
conifold also has such a singularity. Buchel suggested and Gubser et al. have
shown that in the D3-brane case, the naked singularity is cloaked by a horizon
at a sufficiently high temperature. In this paper we derive the system of
second-order differential equations necessary to find such a solution for
. We also find solutions to this system in perturbation theory that
is valid when the Hawking temperature of the horizon is very high.Comment: 22 pages, v2: minor change
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