2,461 research outputs found
Cosmic D--term Strings as Wrapped D3 Branes
We describe cosmic D--term strings as D3 branes wrapped on a resolved
conifold. The matter content that gives rise to D--term strings is shown to
describe the world--volume theory of a space--filling D3 brane transverse to
the conifold which itself is a wrapped D5 brane. We show that, in this brane
theory, the tension of the wrapped D3 brane mathces that of the D--term string.
We argue that there is a new type of cosmic string which arises from fractional
D1 branes on the world--volume of a fractional D3 brane.Comment: 13 pages in phyzzx.tex; eq. (17) corrected, other minor corrections;
v3: more minor correction
Strings and the Holographic Description of Asymptotically de Sitter Spaces
Asymptotically de Sitter spaces can be described by Euclidean boundary
theories with entropies given by the modified Cardy--Verlinde formula. We show
that the Cardy--Verlinde formula describes a string with a rescaled tension
which in fact is a string at the stretched cosmological horizon as seen from
the boundary. The temperature of the boundary theory is the rescaled Hagedorn
temperature of the string. Our results agree with an alternative description of
asymptotically de Sitter spaces in terms of strings on the stretched horizon.
The relation between the two descriptions is given by the large gravitational
redshift between the boundary and the stretched horizon and a shift in energy.Comment: 15 pages in phyzzx.tex, minor correction
Hierarchical Supersymmetry Breaking in Superstring Derived Standard--like Models
We examine the problem of supersymmetry breaking in realistic superstring
standard--like models which are constructed in the free fermionic formulation.
We impose a supersymmetric vacuum at the Planck scale by requiring vanishing F
and D constraints at the cubic level of the superpotential. We then study
possible scenarios for supersymmetry breaking by examining the role of
nonrenormalizable terms and hidden sector gaugino and matter condensates. We
argue that in some scenarios hierarchical supersymmetry breaking in the
observable sector is possible.Comment: IASSNS-HEP-94/17, 31 pages, phyzz
Domain Walls on Singularities
We describe domain walls that live on and singularities. The
walls are BPS if the singularity is resolved and non--BPS if it is deformed and
fibered. We show that these domain walls may interpolate between vacua that
support monopoles and/or vortices.Comment: 16 pages in phyzzx.te
Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation
We describe a D--brane inflation model which consists of two fractional D3
branes separated on a transverse . Inflation arises due to the
resolved orbifold singularity of which corresponds to an anomalous D--term
on the brane. We show that D--brane inflation in the bulk corresponds to
D--term inflation on the brane. The inflaton and the trigger field parametrize
the interbrane distances on an respectively. After inflation the
branes reach a supersymmetric configuration in which they are at the origin of
but separated along the directions.Comment: 15 pages in phyzzx.tex; minor corrections including all factors of
2\pi; v3: more minor correction
Black Hole Entropy and Superconformal Field Theories on Brane-Antibrane Systems
We obtain the enropy of Schwarzschild and charged black holes in D>4 from
superconformal gases that live on p=10-D dimensional brane-antibrane systems
wrapped on T^p. The preperties of the strongly coupled superconformal theories
such as the appearance of hidden dimensions (for p=1,4) and fractional strings
(for p=5) are crucial for our results. In all cases, the Schwarzschild radius
is given by the transverse fluctuations of the branes and antibranes due to the
finite temperature. We show that our results can be generalized to multicharged
black holes.Comment: 24 pages in phyzzx.te
Evaluation of the Theoretical Uncertainties in the W to Lepton and Neutrino Cross Sections at the LHC
We study the sources of systematic errors in the measurement of the W to
lepton and neutrino cross-sections at the LHC. We consider the systematic
errors in both the total cross-section and acceptance for anticipated
experimental cuts. We include the best available analysis of QCD effects at
NNLO in assessing the effect of higher order corrections and PDF and scale
uncertainties on the theoretical acceptance. In addition, we evaluate the error
due to missing NLO electroweak corrections and propose which MC generators and
computational schemes should be implemented to best simulate the events.Comment: 33 pages, 109 eps figures, uses JHEP3.cls, rotating.sty Version 2
corrects an error in Table 1, adds some references, and updates an author
addres
On the Cardy-Verlinde Formula and the de Sitter/CFT Correspondence
We derive the Cardy--Verlinde entropy formula for the field theory that lives
on the boundary of an asymptotically de Sitter space with a black hole. The
boundary theory which is not conformal has a monotonic --function defined by
the Casimir energy. The instability of the space due to Hawking radiation from
the black hole corresponds to an RG flow from the IR to the UV during which
increases. The endpoint of black hole evaporation is de Sitter space which is
described by a conformal theory at the UV fixed point of the RG flow.Comment: 16 pages in phyzzx.tex, the discussion in section 4 clarified, minor
corrections, two references added; v3: the relation between time evolution
and RG flow made explicit, Comments and references adde
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