118340854
Chern–Simons theory with vector fermion matter
We study three-dimensional conformal field theories described by U(N) Chern–Simons theory at level k coupled to massless fermions in the fundamental representation. By solving a Schwinger–Dyson equation in light-cone gauge, we compute the exact planar free energy of the theory at finite temperature on ℝ2 as a function of the ’t Hooft coupling λ=N/k. Employing a dimensional reduction regularization scheme, we find that the free energy vanishes at |λ|=1; the conformal theory does not exist for |λ|>1. We analyze the operator spectrum via the anomalous conservation relation for higher spin currents, and in particular show that the higher spin currents do not develop anomalous dimensions at leading order in 1/N. We present an integral equation whose solution in principle determines all correlators of these currents at leading order in 1/N and present explicit perturbative results for all three-point functions up to two loops. We also discuss a light-cone Hamiltonian formulation of this theory where a W∞ algebra arises. The maximally supersymmetric version of our theory is ABJ model with one gauge group taken to be U(1), demonstrating that a pure higher spin gauge theory arises as a limit of string theory.
118570342
Holography of charged dilaton black holes
We study charged dilaton black branes in AdS4. Our system involves a dilaton ϕ coupled to a Maxwell field Fμν with dilaton-dependent gauge coupling, $ \frac{1}{{{g^2}}} = {f^2}\left( \phi \right) $. First, we find the solutions for extremal and near extremal branes through a combination of analytical and numerical techniques. The near horizon geometries in the simplest cases, where f(ϕ) = eαϕ, are Lifshitz-like, with a dynamical exponent z determined by α. The black hole thermodynamics varies in an interesting way with α, but in all cases the entropy is vanishing and the specific heat is positive for the near extremal solutions. We then compute conductivity in these backgrounds. We find that somewhat surprisingly, the AC conductivity vanishes like ω2 at T = 0 independent of α. We also explore the charged black brane physics of several other classes of gauge-coupling functions f(ϕ). In addition to possible applications in AdS/CMT, the extremal black branes are of interest from the point of view of the attractor mechanism. The near horizon geometries for these branes are universal, independent of the asymptotic values of the moduli, and describe generic classes of endpoints for attractor flows which are different from AdS2 × R2.
119180335
A note on CFT correlators in three dimensions
A bstractIn this note we present a simple method of constructing general conformally invariant three point functions of operators of various spins in three dimensions. Upon further imposing current conservation conditions, we find new parity violating structures for the three point functions involving either the stress-energy tensor, spin one currents, or higher spin currents. We find that all parity preserving structures for conformally invariant three point functions of higher spin conserved currents can be realized by free fields, whereas there is at most one parity violating structure for three point functions for each set of spins, which is not realized by free fields.
39175250
Neutrino mass hierarchy and octant determination with atmospheric neutrinos.
The recent discovery by the Daya-Bay and RENO experiments, that θ(13) is nonzero and relatively large, significantly impacts existing experiments and the planning of future facilities. In many scenarios, the nonzero value of θ(13) implies that θ(23) is likely to be different from π/4. Additionally, large detectors will be sensitive to matter effects on the oscillations of atmospheric neutrinos, making it possible to determine the neutrino mass hierarchy and the octant of θ(23). We show that a 50 kT magnetized liquid argon neutrino detector can ascertain the mass hierarchy with a significance larger than 4σ with moderate exposure times, and the octant at the level of 2-3σ with greater exposure.
119769995
Physics Potential of a 2540 Km Baseline Superbeam Experiment
We study the physics potential of a neutrino superbeam experiment with a 2540 km baseline. We assume a neutrino beam similar to the NuMI beam in the medium energy configuration. We consider a 100 kton totally active scintillator detector at a 7 mr off‐axis location. We find that such a configuration has an outstanding hierarchy discriminating capability. In conjunction with the data from the present reactor neutrino experiments, it can determine the neutrino mass hierarchy at the 3σ level in less than 5 years, if sin22θ13≥0.01, running in the neutrino mode alone. As a stand alone experiment, with a 5 year neutrino run and a 5 year anti‐neutrino run, it can determine non‐zero θ13 at the 3σ level if sin2 2θ13≥7×10−3 and hierarchy at the 3σ level if sin22θ13≥8×10−3. This data can also distinguish δCP = π/2 from the CP conserving values of 0 and π, for sin22θ13≥0.02.
124886230
Mass hierarchy determination using current and upcoming neutrino experiments
Determination of mass hierarchy is a crucial open ended question in neutrino physics today. In the wake of recent T2K [1], MINOS [2] and DChooz [3] results which support a high best-fit to θ13, it is worthwhile to explore the potential of the upcoming and already running neutrino experiments for determining mass hierarchy. We consider the long baseline experiments NOνA and T2K and the reactor neutrino experiments Daya Bay, DChooz and RENO. In our analysis we find out that NOνA by itself is insufficient and would require another long baseline experiment such as T2K. This work assumes that by the time reactor neutrino experiments are over, we will have a precise θ13 information. Final results are presented as hierarchy exclusion plots in sin2 2θ13 − δCP plane.