Hard thermal loops in long wave-length and static external gravitational fields

We study, in the long wave-length and static limits, the structure of the n-point graviton functions at high temperature. Using the gauge and Weyl invariance of the theory, we derive a simple expression for the hard thermal amplitudes in these two limits.Comment: 3 pages, 1 figur

Entanglement of Solitons in the Frenkel-Kontorova Model

We investigate entanglement of solitons in the continuum-limit of the nonlinear Frenkel-Kontorova chain. We find that the entanglement of solitons manifests particle-like behavior as they are characterized by localization of entanglement. The von-Neumann entropy of solitons mixes critical with noncritical behaviors. Inside the core of the soliton the logarithmic increase of the entropy is faster than the universal increase of a critical field, whereas outside the core the entropy decreases and saturates the constant value of the corresponding massive noncritical field. In addition, two solitons manifest long-range entanglement that decreases with the separation of the solitons more slowly than the universal decrease of the critical field. Interestingly, in the noncritical regime of the Frenkel-Kontorova model, entanglement can even increase with the separation of the solitons. We show that most of the entanglement of the so-called internal modes of the solitons is saturated by local degrees of freedom inside the core, and therefore we suggest using the internal modes as carriers of quantum information.Comment: 16 pages, 22 figure

Implications of globalisation for financial stability.

Asia’s share of world trade has expanded constantly over the last two decades. This increase reflects, inter alia, the considerable strengthening of trade links between the countries of the region, fostered by the vertical specialisation of the Asian economies. In the 1980s, the most advanced economies in the region, e.g. Japan, relocated the most labour-intensive stages of their production processes to the newly-industrialised Asian economies like South Korea and Singapore and then, in the 1990s, to emerging Asia, i.e. Indonesia, Malaysia, the Philippines and Thailand. The emergence of China has also given signifi cant impetus to regional trade integration. Surging intra-regional direct investment fl ows have accompanied and shored up trade fl ows, however, portfolio investment fl ows and cross-border bank loans have remained limited. Given that production processes within the region are complementary and that the final destination for exports is outside the region, the lack of a regional exchange rate arrangement in Asia does not appear to be a concern in the short term. Indeed, the regional integration initiatives adopted in Asia in the aftermath of the 1997-1998 financial crisis aim to build further resilience to fi nancial market turbulence. Firstly, deeper and more liquid local bond markets should make it possible to reduce the double financial mismatch, i.e. the currency mismatch and maturity mismatch, which largely sustained the crisis. In this regard, the ASEAN+3 Asian Bond Market Initiative examines the supply-side issues while the Asian Bond Funds initiative of the Executives’ Meeting of East Asia-Pacifi c Central Banks (EMEAP) deals with demand-side issues via the pooling of resources to buy bonds issued by member countries. Secondly, the Chiang Mai Initiative, which consists in a network of currency swap arrangements between the central banks of the ASEAN+3 member states, provides these countries with a regional fi nancial assistance mechanism in the event of a liquidity crisis. The Asian vertical model of production appears to have reached its limit and is evolving towards a more “horizontal” model in terms of both production (substitutability of production processes as a result of the shift towards higher value-added activities) and consumption (expansion of the regional market linked to the growth potential of domestic Chinese demand). Regional monetary co-operation could therefore aim in the future at curbing intra-regional exchange rate fl uctuations in order to promote trade and investment within the region.

Howe Pairs in the Theory of Vertex Algebras

For any vertex algebra V and any subalgebra A of V, there is a new subalgebra of V known as the commutant of A in V. This construction was introduced by Frenkel-Zhu, and is a generalization of an earlier construction due to Kac-Peterson and Goddard-Kent-Olive known as the coset construction. In this paper, we interpret the commutant as a vertex algebra notion of invariant theory. We present an approach to describing commutant algebras in an appropriate category of vertex algebras by reducing the problem to a question in commutative algebra. We give an interesting example of a Howe pair (ie, a pair of mutual commutants) in the vertex algebra setting.Comment: A few typos corrected, final versio

Nonlinear interaction between electromagnetic fields at high temperature

The electron-positron `box' diagram produces an effective action which is fourth order in the electromagnetic field. We examine the behaviour of this effective action at high-temperature (in analytically continued imaginary-time thermal perturbation theory). We argue that there is a finite, nonzero limit as $T\rightarrow \infty$ (where $T$ is the temperature). We calculate this limit in the nonrelativistic static case, and in the long-wavelength limit. We also briefly discuss the self-energy in 2-dimensional QED, which is similar in some respects.Comment: 13 pages, DAMTP 94/3

The Self-Force of a Charged Particle in Classical Electrodynamics with a Cut-off

We discuss, in the context of classical electrodynamics with a Lorentz invariant cut-off at short distances, the self-force acting on a point charged particle. It follows that the electromagnetic mass of the point charge occurs in the equation of motion in a form consistent with special relativity. We find that the exact equation of motion does not exhibit runaway solutions or non-causal behavior, when the cut-off is larger than half of the classical radius of the electron.Comment: 17 pages, 1 figur