Schrodinger:cubic NLS: Difference between revisions

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====Cubic NLS on R====
#REDIRECT [[cubic NLS]]
 
* Scaling is s<sub>c</sub> = -1/2.
* LWP for s <font face="Symbol">³</font> 0 [[Bibliography#Ts1987|Ts1987]], [[Bibliography#CaWe1990|CaWe1990]] (see also [[Bibliography#GiVl1985|GiVl1985]]).
** This is sharp for reasons of Gallilean invariance and for soliton solutions in the focussing case [KnPoVe-p]
*** The result is also sharp in the defocussing case [CtCoTa-p], due to Gallilean invariance and the asymptotic solutions in [[Bibliography#Oz1991|Oz1991]].
*** Below s <font face="Symbol">³</font>0 the solution map was known to be not C<sup>2</sup> in [[Bibliography#Bo1993|Bo1993]]
** For initial data equal to a delta function there are serious problems with existence and uniqueness [KnPoVe-p].
** However, there exist Gallilean invariant spaces which scale below L<sup>2</sup> for which one has LWP. They are defined in terms of the Fourier transform [[Bibliography#VaVe2001|VaVe2001]]. For instance one has LWP for data whose Fourier transform decays like |<font face="Symbol">x</font><nowiki>|^{-1/6-}. Ideally one would like to replace this with |</nowiki><font face="Symbol">x</font><nowiki>|^{0-}.</nowiki>
* GWP for s <font face="Symbol">³</font> 0 thanks to L<sup>2</sup> conservation
** GWP can be pushed below to certain of the Gallilean spaces in [VaVe-p]. For instance one has GWP when the Fourier transform of the data decays like |<font face="Symbol">x</font><nowiki>|^{-5/12-}. Ideally one would like to replace this with 0-.</nowiki>
* If the cubic non-linearity is of <u>u</u> <u>u</u> <u>u</u> or u u u type (as opposed to the usual |u|<sup>2</sup> u type) then one can obtain LWP for s > -5/12 [[references#Gr-p2 Gr-p2]]. If the nonlinearity is of <u>u</u> <u>u</u> u type then one has LWP for s > -2/5 [[references#Gr-p2 Gr-p2]].
* ''Remark''<nowiki>: This equation is sometimes known as the Zakharov-Shabat equation and is completely integrable (see e.g. [</nowiki>[Bibliography#AbKauNeSe1974|AbKauNeSe1974]]; all higher order integer Sobolev norms stay bounded. Growth of fractional norms might be interesting, though.
* In the focusing case there are soliton and multisoliton solutions, however the defocusing case does not admit such solutions.
* In the focussing case there is a unique positive radial ground state for each energy E. By translation and phase shift one thus obtains a four-dimensional manifold of ground states (aka solitons) for each energy. This manifold is H<sup>1</sup>-stable [[Bibliography#Ws1985|Ws1985]], [[Bibliography#Ws1986|Ws1986]]. Below the energy norm orbital stability is not known, however there are polynomial bounds on the instability [[Bibliography#CoKeStTkTa2003b|CoKeStTkTa2003b]].
* This equation is related to the evolution of vortex filaments under the localized induction approximation, via the Hasimoto transformation, see e.g. [[Bibliography#Hm1972|Hm1972]]
* Solutions do not scatter to free Schrodinger solutions. In the focussing case this can be easily seen from the existence of solitons. But even in the defocussing case wave operators do not exist, and must be replaced by modified wave operators [[Bibliography#Oz1991|Oz1991]], see also [CtCoTa-p]. For small, decaying data one also has asymptotic completeness [[Bibliography#HaNm1998|HaNm1998]].
** For large Schwartz data, these asymptotics can be obtained by inverse scattering methods [[Bibliography#ZkMan1976|ZkMan1976]], [[Bibliography#SeAb1976|SeAb1976]], [[Bibliography#No1980|No1980]], [[Bibliography#DfZx1994|DfZx1994]]
** For large real analytic data, these asymptotics were obtained in [[Bibliography#GiVl2001|GiVl2001]]
** Refinements to the convergence and regularity of the modified wave operators was obtained in [[Bibliography#Car2001|Car2001]]
* On the half line R^+, global well-posedness in H^2 was established in [[references:CrrBu.1991 CrrBu.1991]], [[references:Bu.1992 Bu.1992]]
* On the interval, the inverse scattering method was applied to generate solutions in [GriSan-p].
 
[[Category:Equations]]
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Latest revision as of 04:30, 29 July 2006

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