hep-th/0411011

Landscape, the Scale of SUSY Breaking, and Inflation

We argue that in the simplest version of the KKLT model, the maximal value of the Hubble constant during inflation cannot exceed the present value of the gravitino mass, H< m_{3/2}. This may have important implications for string cosmology and for the scale of the SUSY breaking in this model. If one wants to have inflation on high energy scale, one must develop phenomenological models with an extremely large gravitino mass. On the other hand, if one insists that the gravitino mass should be O(1 TeV), one will need to develop models with a very low scale of inflation. We show, however, that one can avoid these restrictions in a more general class of KKLT models based on the racetrack superpotential with more than one exponent. In this case one can combine a small gravitino mass and low scale of SUSY breaking with the high energy scale of inflation.

DeDeo, astro-ph/0411283

Particle Dark Energy
Authors: Simon DeDeo
Comments: 7 pages, 5 figures, submitted to Phys. Rev. D

We explore the physics of a gas of particles interacting with a condensate that spontaneously breaks Lorentz invariance. The equation of state of this gas varies from 1/3 to less than -1 and can lead to the observed cosmic acceleration. The particles are always stable. In our particular class of models these particles are fermions with a chiral coupling to the condensate. They may behave as relativistic matter at early times, produce a brief period where they dominate the expansion with w<0 today, and behave as matter at late time. There are no small parameters in our models, which generically lead to dark energy clustering and, depending on the choice of parameters, smoothing of small scale power.

http://arxiv.org/abs/astro-ph/0411283

Team Members

I have been informed that the invites that I sent out to join the blog don't seem to work very well. But, if u log in with the user id and passwd I gave u, and then just invite yourself, it seems to work fine. Whatever works I guess...

Nieto, Turyshev, and Anderson (posted by Sean)

Paper: gr-qc/0411077
Date: Mon, 15 Nov 2004 22:27:55 GMT (566kb)

Title: The Pioneer Anomaly: The Data, its Meaning, and a Future Test
Authors: Michael Martin Nieto, Slava G. Turyshev, and John D. Anderson
Comments: 16 pages, 7 figures, to be published in the AIP Conference
Proceedings of the 2nd Mexican Meeting on Mathematical and Experimental
Physics
Report-no: LA-UR-04-7368
\ The radio-metric Doppler tracking data from the Pioneer 10/11 spacecraft, from between 20-70 AU, yields an unambiguous and independently confirmed anomalous blue shift drift of a_t = (2.92 \pm 0.44)\times 10^{-18} s/s^2. It can be interpreted as being due to a constant acceleration of a_P = (8.74 \pm 1.33) \times 10^{-8} cm/s^2 directed towards the Sun. No systematic effect has been able to explain the anomaly, even though such an origin is an obvious candidate. We discuss what has been learned (and what might still be learned) from the data about the anomaly, its origin, and the mission design characteristics that would be needed to test it. Future mission options are proposed.
\\ ( http://arXiv.org/abs/gr-qc/0411077 , 566kb)

Schuller and Wohlfarth (posted by Sean)

\Paper: gr-qc/0411076
Date: Mon, 15 Nov 2004 21:53:06 GMT (10kb)

Title: Classical limit of quantum gravity in an accelerating universe
Authors: Frederic P. Schuller, Mattias N.R. Wohlfarth
Comments: 4 pages, no figures
\ A one-parameter deformation of Einstein-Hilbert gravity with an inverse
curvature term is derived as the classical limit of quantum gravity compatible
with an accelerating universe. This result is based on the investigation of
semi-classical theories with sectional curvature bounds which are shown not to
admit static black holes if otherwise of phenomenological interest.
Consequences for classical gravity and the canonical quantization program are
briefly discussed.
\\ ( http://arXiv.org/abs/gr-qc/0411076 , 10kb)

Welcome

OK, so I think this should work pretty well... if we actually use it. PLZ do - I think this is an excellent idea.