10,792 research outputs found
Inelastic neutron scattering peak in Zn substituted YBa2Cu3O7
The effects of nonmagnetic impurities on the neutron scattering intensity are
studied for a model of the copper oxide layers in the normal state. The
contribution to the Q=(pi,pi) neutron scattering intensity from processes
involving the scattering of the spin fluctuations from an impurity with large
momentum transfers are calculated within the random phase approximation. It is
shown that this type of scatterings could lead to a peak in the neutron
scattering intensity in the normal state.Comment: 4 pages, 4 figure
An optimal decay estimate for the linearized water wave equation in 2D
We obtain a decay estimate for solutions to the linear dispersive equation
for . This
corresponds to a factorization of the linearized water wave equation
. In particular, by making use of the
Littlewood-Paley decomposition and stationary phase estimates, we obtain decay
of order for solutions corresponding to data ,
assuming only bounds on and . As another application of these
ideas, we give an extension to equations of the form
for a wider range of .Comment: New result added (see Section 3). To appear in Proc. Amer. Math. So
The defocusing energy-supercritical cubic nonlinear wave equation in dimension five
We consider the energy-supercritical nonlinear wave equation with defocusing cubic nonlinearity in dimension with no
radial assumption on the initial data. We prove that a uniform-in-time {\it a
priori} bound on the critical norm implies that solutions exist globally in
time and scatter at infinity in both time directions. Together with our earlier
works in dimensions with general data and dimension with radial
data, the present work completes the study of global well-posedness and
scattering in the energy-supercritical regime for the cubic nonlinearity under
the assumption of uniform-in-time control over the critical norm.Comment: AMS Latex, 45 pages. Final versio
Negative energy blowup results for the focusing Hartree hierarchy via identities of virial and localized virial type
We establish virial and localized virial identities for solutions to the
Hartree hierarchy, an infinite system of partial differential equations which
arises in mathematical modeling of many body quantum systems. As an
application, we use arguments originally developed in the study of the
nonlinear Schr\"odinger equation (see work of Zakharov, Glassey, and
Ogawa--Tsutsumi) to show that certain classes of negative energy solutions must
blow up in finite time.
The most delicate case of this analysis is the proof of negative energy
blowup without the assumption of finite variance; in this case, we make use of
the localized virial estimates, combined with the quantum de Finetti theorem of
Hudson and Moody and several algebraic identities adapted to our particular
setting. Application of a carefully chosen truncation lemma then allows for the
additional terms produced in the localization argument to be controlled.Comment: 25 pages, final versio
Maximizers for the Strichartz Inequalities for the Wave Equation
We prove the existence of maximizers for Strichartz inequalities for the wave
equation in dimensions . Our approach follows the scheme given by
Shao, which obtains the existence of maximizers in the context of the
Schr\"odinger equation. The main tool that we use is the linear profile
decomposition for the wave equation which we prove in , , extending the profile decomposition result of Bahouri and Gerard,
previously obtained in .Comment: 28 pages, revised version, minor change
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