13,638 research outputs found
Coherence effects in disordered geometries with a field-theory dual
We investigate the holographic dual of a probe scalar in an asymptotically
Anti-de-Sitter (AdS) disordered background which is an exact solution of
Einstein's equations in three bulk dimensions. Unlike other approaches to model
disorder in holography, we are able to explore quantum wave-like interference
effects between an oscillating or random source and the geometry. In the
weak-disorder limit, we compute analytically and numerically the one-point
correlation function of the dual field theory for different choices of sources
and backgrounds. The most interesting feature is the suppression of the
one-point function in the presence of an oscillating source and weak random
background. We have also computed analytically and numerically the two-point
function in the weak disorder limit. We have found that, in general, the
perturbative contribution induces an additional power-law decay whose exponent
depends on the distribution of disorder. For certain choices of the gravity
background, this contribution becomes dominant for large separations which
indicates breaking of perturbation theory and the possible existence of a phase
transition induced by disorder.Comment: 36 pages, 19 figs, v3 accepted versio
BanksÂ’ participation in the Eurosystem auctions and money market integration
Bidding Behaviour, auctions, open market operations, money market, liquidity management Abstract: We perform a panel analysis of bidding in the Eurosystem auctions, using individual data that include the bidder code, size, nationality and membership in a banking group. We find that an increase in interest rate volatility lowers the probability of bidding, but induces bidders to shade rates less. Large bidders participate more regularly, while group bidders demand larger amounts, showing an aptitude to act as liquidity brokers. Our findings support the transnational bank hypothesis (Freixas- Holthausen, 2005): banks with a multinational profile use their informational advantage to arbitrage out the differences in interest rates across countries, thus fostering money market integration.
Regularization of energy-momentum tensor correlators and parity-odd terms
We discuss the problem of regularizing correlators in conformal field
theories. The only way to do it in coordinate space is to interpret them as
distributions. Unfortunately except for the simplest cases we do not have
tabulated mathematical results. The way out we pursue here is to go to momentum
space and use Feynman diagram techniques and their regularization methods. We
focus on the energy-momentum tensor correlators and, to gain insight, we
compute and regularize 2-point functions in 2d with various techniques both in
coordinate space and in momentum space, obtaining the same results. Then we do
the same for 2-point functions in 4d. Finally we turn to 3-point function in
4d, and concentrate on the parity-odd part. We derive in particular the
regularized trace and divergence of the energy-momentum tensor in a chiral
fermion model. We discuss the problems related to the parity-odd trace anomaly.Comment: 40 pages, 1 figure. v2: minor changes and typos correcte
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