184 research outputs found
Open Heterotic Strings
We classify potential cosmic strings according to the topological charge
measurable outside the string core. We conjecture that in string theory it is
this charge that governs the stability of long strings. This would imply that
the SO(32) heterotic string can have endpoints, but not the E_8 x E_8 heterotic
string. We give various arguments in support of this conclusion.Comment: 15 pages. v.2: typos, references correcte
Perturbative dynamics of matrix string for the membrane
Recently Sekino and Yoneya proposed a way to regularize the world volume
theory of membranes wrapped around by matrices and showed that one
obtains matrix string theory as a regularization of such a theory. We show that
this correspondence between matrix string theory and wrapped membranes can be
obtained by using the usual M(atrix) theory techniques. Using this
correspondence, we construct the super-Poincare generators of matrix string
theory at the leading order in the perturbation theory. It is shown that these
generators satisfy 10 dimensional super-Poincar\'e algebra without any anomaly.Comment: 23 pages, 1 figur
Towards the deconstruction of M-theory
We argue that there is an equivalence of M-theory on T^3 \times A_{N-1} with
a four-dimensional non-supersymmetric quiver gauge theory on the Higgs branch.
The quiver theory in question has gauge group SU(N)^{N_4N_6N_8} and is
considered in a strong coupling and large N_{4,6,8} limit. We provide field-
and string-theoretical evidence for the equivalence making use of the
deconstruction technique. In particular, we find wrapped M2-branes in the mass
spectrum of the quiver theory at low energies.Comment: LaTeX, 15 pages, 4 figures, added reference
A geometric discretisation scheme applied to the Abelian Chern-Simons theory
We give a detailed general description of a recent geometrical discretisation
scheme and illustrate, by explicit numerical calculation, the scheme's ability
to capture topological features. The scheme is applied to the Abelian
Chern-Simons theory and leads, after a necessary field doubling, to an
expression for the discrete partition function in terms of untwisted
Reidemeister torsion and of various triangulation dependent factors. The
discrete partition function is evaluated computationally for various
triangulations of and of lens spaces. The results confirm that the
discretisation scheme is triangulation independent and coincides with the
continuum partition functionComment: 27 pages, 5 figures, 6 tables. in late
Restoring New Agegraphic Dark Energy in RS II Braneworld
Motivated by recent works [1,2], we investigate new agegraphic model of dark
energy in the framework of RS II braneworld. We also include the case of
variable gravitational constant in our model. Furthermore, we establish
correspondence between the new agegraphic dark energy with other dark energy
candidates based on scalar fields.Comment: 13 pages, accepted for publication in IJT
Cosmic coincidence problem and variable constants of physics
The standard model of cosmology is investigated using time dependent
cosmological constant and Newton's gravitational constant . The
total energy content is described by the modified Chaplygin gas equation of
state. It is found that the time dependent constants coupled with the modified
Chaplygin gas interpolate between the earlier matter to the later dark energy
dominated phase of the universe. We also achieve a convergence of parameter
, with minute fluctuations, showing an evolving . Thus our
model fairly alleviates the cosmic coincidence problem which demands
at present time.Comment: 27 pages, 15 figure
Statefinder Parameter for Varying G in Three Fluid System
In this work, we have considered variable G in flat FRW universe filled with
the mixture of dark energy, dark matter and radiation. If there is no
interaction between the three fluids, the deceleration parameter and
statefinder parameters have been calculated in terms of dimensionless density
parameters which can be fixed by observational data. Also the interaction
between three fluids has been analyzed due to constant . The statefinder
parameters also calculated in two cases: pressure is constant and pressure is
variable.Comment: 5 pages, Accepted for publication in "Astrophysics and Space Science
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
Renormalization group flows and continual Lie algebras
We study the renormalization group flows of two-dimensional metrics in sigma
models and demonstrate that they provide a continual analogue of the Toda field
equations based on the infinite dimensional algebra G(d/dt;1). The resulting
Toda field equation is a non-linear generalization of the heat equation, which
is integrable in target space and shares the same dissipative properties in
time. We provide the general solution of the renormalization group flows in
terms of free fields, via Backlund transformations, and present some simple
examples that illustrate the validity of their formal power series expansion in
terms of algebraic data. We study in detail the sausage model that arises as
geometric deformation of the O(3) sigma model, and give a new interpretation to
its ultra-violet limit by gluing together two copies of Witten's
two-dimensional black hole in the asymptotic region. We also provide some new
solutions that describe the renormalization group flow of negatively curved
spaces in different patches, which look like a cane in the infra-red region.
Finally, we revisit the transition of a flat cone C/Z_n to the plane, as
another special solution, and note that tachyon condensation in closed string
theory exhibits a hidden relation to the infinite dimensional algebra G(d/dt;1)
in the regime of gravity. Its exponential growth holds the key for the
construction of conserved currents and their systematic interpretation in
string theory, but they still remain unknown.Comment: latex, 73pp including 14 eps fig
Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV
Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7ââfbâ1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale
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