Packages for the release of KDE’s desktop suite Plasma 5.3 beta are available for Kubuntu Vivid. You can get it from the Kubuntu Beta PPA.
Bugs in the packaging should be reported to kubuntu-ppa on Launchpad. Bugs in the software to KDE.
To update, use the Software Repository Guide to add the following repository to your software sources list:
ppa:kubuntu-ppa/beta