## A sharp $k$-plane Strichartz inequality for the Schrödinger equation

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- by Jonathan Bennett, Neal Bez, Taryn C. Flock, Susana Gutiérrez and Marina Iliopoulou PDF
- Trans. Amer. Math. Soc.
**370**(2018), 5617-5633 Request permission

## Abstract:

We prove that \begin{equation*} \|X(|u|^2)\|_{L^3_{t,\ell }}\leq C\|f\|_{L^2(\mathbb {R}^2)}^2, \end{equation*} where $u(x,t)$ is the solution to the linear time-dependent Schrödinger equation on $\mathbb {R}^2$ with initial datum $f$ and $X$ is the (spatial) X-ray transform on $\mathbb {R}^2$. In particular, we identify the best constant $C$ and show that a datum $f$ is an extremiser if and only if it is a gaussian. We also establish bounds of this type in higher dimensions $d$, where the X-ray transform is replaced by the $k$-plane transform for any $1\leq k\leq d-1$. In the process we obtain sharp $L^2(\mu )$ bounds on Fourier extension operators associated with certain high-dimensional spheres involving measures $\mu$ supported on natural “co-$k$-planarity” sets.## References

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## Additional Information

**Jonathan Bennett**- Affiliation: School of Mathematics, The Watson Building, University of Birmingham, Edgbaston, Birmingham, B15 2TT, England
- MR Author ID: 625531
- Email: j.bennett@bham.ac.uk
**Neal Bez**- Affiliation: Department of Mathematics, Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
- MR Author ID: 803270
- Email: nealbez@mail.saitama-u.ac.jp
**Taryn C. Flock**- Affiliation: School of Mathematics, The Watson Building, University of Birmingham, Edgbaston, Birmingham, B15 2TT, England
- Address at time of publication: Department of Mathematics and Statistics, Lederle Graduate Research Tower, University of Massachusetts, Amherst, Massachusetts 01003-9305
- MR Author ID: 976421
- Email: flock@math.umass.edu
**Susana Gutiérrez**- Affiliation: School of Mathematics, The Watson Building, University of Birmingham, Edgbaston, Birmingham, B15 2TT, England
- Email: s.gutierrez@bham.ac.uk
**Marina Iliopoulou**- Affiliation: Department of Mathematics, University of California, Berkeley, California 94720-3840
- MR Author ID: 1017823
- Email: m.iliopoulou@berkeley.edu
- Received by editor(s): December 9, 2016
- Published electronically: March 20, 2018
- Additional Notes: The work of the first, third, and fifth authors was supported by the European Research Council (grant number 307617).

The work of the second author was supported by a JSPS Grant-in-Aid for Young Scientists (A) (grant number 16H05995) - © Copyright 2018 American Mathematical Society
- Journal: Trans. Amer. Math. Soc.
**370**(2018), 5617-5633 - MSC (2010): Primary 42B37, 35A23
- DOI: https://doi.org/10.1090/tran/7309
- MathSciNet review: 3803144