4 research outputs found
LHC String Phenomenology
We argue that it is possible to address the deeper LHC Inverse Problem, to
gain insight into the underlying theory from LHC signatures of new physics. We
propose a technique which may allow us to distinguish among, and favor or
disfavor, various classes of underlying theoretical constructions using
(assumed) new physics signals at the LHC. We think that this can be done with
limited data , and improved with more data. This is because of
two reasons -- a) it is possible in many cases to reliably go from
(semi)realistic microscopic string construction to the space of experimental
observables, say, LHC signatures. b) The patterns of signatures at the LHC are
sensitive to the structure of the underlying theoretical constructions. We
illustrate our approach by analyzing two promising classes of string
compactifications along with six other string-motivated constructions. Even
though these constructions are not complete, they illustrate the point we want
to emphasize. We think that using this technique effectively over time can
eventually help us to meaningfully connect experimental data to microscopic
theory.Comment: 50 Pages, 13 Figures, 3 Tables, v2: minor changes, references adde
Testing String Theory with CMB
Future detection/non-detection of tensor modes from inflation in CMB
observations presents a unique way to test certain features of string theory.
Current limit on the ratio of tensor to scalar perturbations, r=T/S, is r <
0.3, future detection may take place for r > 10^{-2}-10^{-3}. At present all
known string theory inflation models predict tensor modes well below the level
of detection. Therefore a possible experimental discovery of tensor modes may
present a challenge to string cosmology.
The strongest bound on r in string inflation follows from the observation
that in most of the models based on the KKLT construction, the value of the
Hubble constant H during inflation must be smaller than the gravitino mass. For
the gravitino mass in the usual range, m_{3/2} < O(1) TeV, this leads to an
extremely strong bound r < 10^{-24}. A discovery of tensor perturbations with r
> 10^{-3} would imply that the gravitinos in this class of models are
superheavy, m_{3/2} > 10^{13} GeV. This would have important implications for
particle phenomenology based on string theory.Comment: 13 pages, 2 figure
The Supermembrane with Central Charges on a G2 Manifold
We construct the 11D supermembrane with topological central charges induced
through an irreducible winding on a G2 manifold realized from the T7/Z2xZ2xZ2
orbifold construction. The hamiltonian H of the theory on a T7 target has a
discrete spectrum. Within the discrete symmetries of H associated to large
diffeomorphisms, the Z2xZ2xZ2 group of automorphisms of the quaternionic
subspaces preserving the octonionic structure is relevant. By performing the
corresponding identification on the target space, the supermembrane may be
formulated on a G2 manifold, preserving the discretness of its supersymmetric
spectrum. The corresponding 4D low energy effective field theory has N=1
supersymmetry.Comment: Reviewed version. spectral propertis discussed, two more sections
added, 27 pages,Late
Volume Modulus Inflation and the Gravitino Mass Problem
The Hubble constant during the last stages of inflation in a broad class of
models based on the KKLT mechanism should be smaller than the gravitino mass, H
<~ m_{3/2}. We point out that in the models with large volume of
compactification the corresponding constraint typically is even stronger, H <~
m_{3/2}^{3/2}, in Planck units. In order to address this problem, we propose a
class of models with large volume of compactification where inflation may occur
exponentially far away from the present vacuum state. In these models, the
Hubble constant during inflation can be many orders of magnitude greater than
the gravitino mass. We introduce a toy model describing this scenario, and
discuss its strengths and weaknesses.Comment: 24 pages, JHEP style; v2. refs adde