The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The rare kaon decay K + ->π - μ + μ + is violating lepton number by two units and is investigated within the context of Majorana neutrino masses. Using a new upper bound from E865 an upper limit on the effective Majorana mass term <m μμ > 500 GeV could be obtained. This is improving existing bounds by about one order of magnitude. Implications on heavy neutrinos are discussed as well as future possibilities to improve limits on this as well as other elements of the Majorana mass matrix are investigated.