129 research outputs found
Quantum Aspects of Massive Gravity II: Non-Pauli-Fierz Theory
We investigate the non-Pauli-Fierz(nPF) theory, a linearized massive gravity
with a generic graviton mass term, which has been ignored due to a ghost in its
spectrum and the resultant loss of unitarity. We first show that it is possible
to use the Lee-Wick mechanism, a unitarization through the decay of a ghost, in
order to handle the sixth mode ghost of nPF, and then check for the quantum
consistency. Once proven to be consistent, nPF could become a viable candidate
for a large distance modification of gravity, because it naturally solves the
intrinsic problems that most dark energy/modified gravity models suffer from:
It smoothly converges to general relativity at short distances, and the small
graviton mass necessary to modify gravity at large scales can be stable under
the radiative corrections from the minimal gravity-to-matter coupling.Comment: 1+16pp, accepted for JHE
Climatic risks and impacts in South Asia: extremes of water scarcity and excess
This paper reviews the current knowledge of climatic risks and impacts in South Asia associated with anthropogenic warming levels of 1.5°C to 4°C above pre-industrial values in the 21st century. It is based on the World Bank Report “Turn Down the Heat, Climate Extremes, Regional Impacts and the Case for Resilience” (2013). Many of the climate change impacts in the region, which appear quite severe even with relatively modest warming of 1.5–2°C, pose significant hazards to development. For example, increased monsoon variability and loss or glacial meltwater will likely confront populations with ongoing and multiple challenges. The result is a significant risk to stable and reliable water resources for the region, with increases in peak flows potentially causing floods and dry season flow reductions threatening agriculture. Irrespective of the anticipated economic development and growth, climate projections indicate that large parts of South Asia’s growing population and especially the poor are likely to remain highly vulnerable to climate change
Universality of anomalous conductivities in theories with higher-derivative holographic duals
Effective holographic theories of momentum relaxation and violation of conductivity bound
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