Search Talks

We present a new model of inflation which does not rely on fundamental scalar fields.  The theory is a conformally invariant gauge field theory minimally coupled to massless fermions.  At the beginning of inflation, the conformal symmetry is dynamically broken by a BCS condensation of the fermions, leading to a spontaneously violation of conformal symmetry.  A quasi de-Sitter inflationary regime is driven by the interaction between a homogenous plasma dynamo between the gauge, gravitational and condensate field.  Unique observational consequences of this model are twofold : (1) The sourcing of B-mode vorticity fluctuations in upcoming CMB powerspectra. (2) A possible inflationary Baryogenesis mechanism connected to the initial conditions of inflation.

In 2-dim it is known that a unitary, well defined quantum field theory, if scale invariant must also be invariant under conformal transformations. Whether this is also true in dimensions higher than two has been an open question for decades. We have discovered renomalization group flows in 4-epsilon dimensions corresponding to scale but not conformal invariant theories. The flows correspond to limit cycles or ergodic behavior,  neither of which had been reported in relativistic quantum field theories either.   There seems to be a deep connection between scale without conformal invariance and this type of renormalization group  behavior. We will present these results and list some of open questions, including the possibility of such behavior in integral dimensions.

It is well known that on-shell recursion relation can be applied to tree-level amplitude in string theory. One technical issue of the application is the sum of infinite middle on-shell states. We discuss how we can do the sum exactly to reproduce the known result.

With the emergence of the dark sector in cosmology,  a variety of modified theories of gravity have come to the fore. I will discuss a framework which can be used to test gravity on large scales and the observational programmes that might lead to the tightest constraints.

The IceCube neutrino observatory is the world's largest high-energy neutrino telescope, utilizing the deep Antarctic ice as the Cherenkov detector medium.  In December 2010 the last of the observatory's 86 strings of optical detectors was deployed, completing the approximate cubic-kilometer array.   With the addition of a low-energy extension, called DeepCore, the observatory has very high neutrino detection efficiency for energies ranging from ~10 GeV to a few EeV.  The low-energy threshold establishes the first steps towards precision neutrino measurements in the Antarctic. Discussed will be early results from this emerging particle physics program as well as initial expectations from studies of potential future detector upgrades towards creating a multi-megaton neutrino detector with O(10 MeV) energy threshold.