1,150 research outputs found
Contact surgeries and the transverse invariant in knot Floer homology
We study naturality properties of the transverse invariant in knot Floer
homology under contact (+1)-surgery. This can be used as a calculational tool
for the transverse invariant. As a consequence, we show that the
Eliashberg-Chekanov twist knots E_n are not transversely simple for n odd and
n>3.Comment: Corrected naturality discussion
Condensation of quasiparticles and density modulation beyond the superfluid critical velocity
We investigate the effect of a constant external velocity field on the ground
state of a bosonic quasiparticle Hamiltonian. Below a critical velocity the
ground state is a quasiparticle vacuum, corresponding to a pure superfluid
phase at zero temperature. Beyond the critical velocity energy minimization
leads to a macroscopic condensation of quasiparticles at a nonzero wave vector
k_v parallel to the velocity v. Simultaneously, physical particles also undergo
a condensation at k_v and, to a smaller extent, at -k_v. Together with the BEC
at k=0, the three entangled condensates give rise to density modulations of
wave vectors k_v and 2k_v. For larger |v| our model predicts a bifurcation of
k_v with corresponding two pure condensates and no density modulation.Comment: Proof of quasiparticle condensation complete
Concordance homomorphisms from knot Floer homology
We modify the construction of knot Floer homology to produce a one-parameter
family of homologies for knots in the three-sphere. These invariants can be
used to give homomorphisms from the smooth concordance group to the integers,
giving bounds on the four-ball genus and the concordance genus of knots. We
give some applications of these homomorphisms.Comment: Minor revision, corrected typos and added explanation to Chapter
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