Lost cousins: Gell-Mann--Low renormalization group and Pad approximation

Note: 10:00 AM
Speaker: Vanja Dunjko, University of Massachusetts, Boston

When: February 10, 2010 (Wed), 10:00AM to 11:00AM (add to my calendar)

This event is part of the Condensed Matter Theory Seminar Series.

Abstract: In the single-variable case, Gell-Mann—Low renormalization group (GLM RG)
requires no special symmetries and is thus a purely formal method for improving
convergence properties of series expansions. In fact, up to a series reversion,
it is a type of integral Hermite-Pad approximation. It is especially useful
for interpolating between expansions for small values of a variable and a
scaling law of known exponent for large values. As an example, we extract the
scaling-law prefactor for the one-body density matrix of the Lieb-Liniger gas.
Using a new result for the 4th-order term in the short-distance expansion, we
find a remarkable agreement with known ab initio numerical results.