Preprints

C. Arezzo, F. Pacard and M. Singer. Extremal Kähler metrics on blow-ups.

Abstract : We present some new results about the existence of extremal Kähler metrics on blow-ups of Kähler manifolds. As a consequence of our results, we obtain extremal metrics on the blow up of P^m at n=1, ... , m+1 linearly independent points.
                                                                                                     Here is the final version  and also the original version 

M. Musso, F. Pacard and J. Wei. Finite energy, sign changing solutions with dihedral symmetry for the stationary non linear Schrödinger equation.

Abstract : We address the problem of the existence of finite energy solitary  waves for nonlinear Klein-Gordon or Schrodinger type equations. Under natural conditions on the nonlinearity, we prove the  existence of infinitely many nonradial solutions in any dimension N ≥ 2. Our result complements earlier works of Bartsch and Willem and Lorca-Ubilla where solutions invariant under the action of O(2) × O(N − 2) are constructed. In contrast, the solutions we construct are invariant under the action of Dk × O(N − 2) where Dk ⊂ O(2) denotes the subgroup generated by the rotation of angle 2π/k, for some integer k ≥ 7, but  they are not invariant under the action of O(2) × O(N − 2).



F. Helein, L. Hauswirth and F. Pacard. A note on some overdetermined problem.

Abstract : In this short note, we address the classification of all flat surfaces M with smooth boundary on which there exist positive harmonic functions having 0 Dirichlet data and constant (nonzero) Neumann data. In particular, we show that this problem bear strong similarities with the study os minimal surfaces in Euclidean 3-space. We also provide a Weierstrass type representation formula for these surfaces.



M. del Pino, M. Musso, F. Pacard and A. Pistoia. Torus action on S^n and sign changing solutions for conformally invariant equations.

Abstract : We construct sequences of sign changing solutions for some conformally invariant semilinear elliptic equation which is defined in S^n, with n 4. The solutions we obtain have large energy and concentrate along some special submanifolds of S^n. For example, in dimension n 4 we obtain sequences of solutions whose energy concentrates along one great circle or finitely many great circles which are linked (a Hopf link). In dimension n 5, we obtain sequences of solutions whose energy concentrates along a two dimensional torus (a Clifford torus).



F. Pacard. Constant scalar curvature and extremal metrics on blow ups.

Abstract : In this paper, we report some joint works with C. Arezzo and M. Singer concerning the construction of extremal Kahler metrics on blow ups at finitely many points of Kahler manifolds which already carry an extremal metric. In particular, we give sufficient conditions on the number and locations of the blow up points for the blow up to carry an extremal Kahler metrics.



F. Pacard. Lectures on "Connected sum constructions in geometry and nonlinear analysis".

Abstract  : These are notes which cover the lectures I gave in the spring of 2006 in Roma I-La Sapienza and they also cover the lectures I gave in the spring of 2007 in the ETH for some Nachdiplomvorlesung. These lectures cover the analysis of some class of elliptic second order operators on manifolds with asymptotically periodic ends which appear in the analysis of some geometric problems : constant mean curvature surfaces, singular Yamabe problem, ...
So far the first part is complete. It contains all the necessary information to understand the linear analysis for some class of ellitpic operators which are defined on manifolds with asymptotically periodic ends. 

The second part will contain applications of the results of the first part for the understanding of the theory of constant mean curvature surfaces, complete constant scalar curvature metrics and also some application to some singular perturbation problems. This part is not yet finished but I am working on it...and I will do my best to update the latest version on this web page.