Pantheon SEMPARIS Le serveur des sťminaires parisiens Paris

Status Confirmed
Seminar Series IPHT-PHM
Subjects math-ph
Date Monday 1 October 2018
Time 11:00
Institute IPHT
Seminar Room Salle Claude Itzykson, B‚t. 774
Speaker's Last Name Ivan Dornic
Speaker's First Name
Speaker's Email Address
Speaker's Institution SPEC, CEA/Saclay
Title A tale of Pfaffian persistence tails told by a Painlevť VI transcendent
Abstract We identify the¬† persistence probability for the spin located at the origin of a half-space magnetized Glauber-Ising chain as a Fredholm Pfaffian gap probability generating function with a sech-kernel. This is then recast as¬† a tau-function for a certain Painlevé VI transcendent --- a sort of exact Kramers' formula¬† for the associated explicitely¬† time-dependent Hamiltonian ---¬† where the persistence exponent emerges as an asymptotic decay rate. By a¬† known yet remarkable correspondence that relates Painlevé equations to Bonnet surfaces, the persistence probability has also a geometric meaning √† la Gauss-Bonnet in terms of the intrinsic curvature of the underlying surface. Since the same¬† sech-kernel with an underlying Pfaffian structure shows up in a variety of Gaussian first-passage problems, our Painlevé VI characterization appears as a¬† universal probability distribution akin to the famous Painlevé II Tracy-Widom laws. Its tail behavior¬† in the magnetization-symmetric case allows in particular to recover the exact value 3/16 for the persistence exponent of a 2d diffusing random field, as found very recently by Poplavskyi and Schehr (arXiv:1806.11275). Due to its topological origin, this value should constitute the super-universal persistence exponent for the coarsening of a non-conserved scalar order parameter in two space dimensions.
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