1,006 research outputs found
Negative energy antiferromagnetic instantons forming Cooper-pairing "glue" and "hidden order" in high-Tc cuprates
An emergence of magnetic boson of instantonic nature, that provides a
Cooper-'pairing glue', is considered in the repulsive 'nested' Hubbard model of
superconducting cuprates. It is demonstrated, that antiferromagnetic instantons
of a spin density wave type may have negative energy due to coupling with
Cooper pair condensate. A set of Eliashberg-like equations is derived and
solved self-consistently, proving the above suggestion. An instantonic
propagator plays the role of Green function of pairing 'glue' boson.
Simultaneously, the instantons defy condensation of the mean-field SDW order.
We had previously demonstrated in analytical form \cite{2,3,4} that periodic
chain of instanton-anti-instanton pairs along the axis of Matsubara time has
zero scattering cross section for weakly perturbing external probes, like
neutrons, etc., thus representing a 'hidden order'. Hence, the two competing
orders, superconducting and antiferromagnetic, may coexist (below some Tc) in
the form of mean-field superconducting order, coupled to 'hidden'
antiferromagnetic one. This new picture is discussed in relation with the
mechanism of high temperature superconductivity
Path description of type B q-characters
We give a set of sufficient conditions for a Laurent polynomial to be the
q-character of a finite-dimensional irreducible representation of a quantum
affine group. We use this result to obtain an explicit path description of
q-characters for a class of modules in type B. In particular, this proves a
conjecture of Kuniba-Ohta-Suzuki.Comment: 32 pages, late
Affinization of category O for quantum groups
Let g be a simple Lie algebra. We consider the category ĖO of those modules over the affine quantum group Uq(bg) whose Uq(g)-weights have finite multiplicity and lie in a finite union of cones generated by negative roots. We show that many properties of the category of the finite-dimensional representations naturally extend to the category ĖO . In particular, we develop the theory of q-characters and define the minimal affinizations of parabolic Verma modules. In types ABCFG we classify these minimal affinizations and conjecture a Weyl denominator type formula for their characters.Peer reviewedFinal Accepted Versio
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