TY - JOUR T1 - Global Well-posedness for the Klein-Gordon Equation Below the Energy Norm JO - Journal of Partial Differential Equations VL - 2 SP - 97 EP - 121 PY - 2004 DA - 2004/05 SN - 17 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/jpde/5380.html KW - Klein-Gordon equations KW - Strichartz estimates KW - Besov spaces KW - wellposedness AB - We study global well-posedness below the energy norm of the Cauchy problem for the Klein-Gordon equation in R^n with n ≥ 3. By means of Bourgain's method along with the endpoint Strichartz estimates of Keel and Tao, we prove the H^s-global well-posedness with s < 1 of the Cauchy problem for the Klein-Gordon equation. This we do by establishing a series of nonlinear a priori estimates in the setting of Besov spaces.