<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Dear OpenLoops user,<div class=""><br class=""></div><div class="">we just released an updated version of OpenLoops (OpenLoops-1.3, svn: 1942; <a href="http://www.hepforge.org/archive/openloops/OpenLoops-1.3.0.tar.gz" class="">http://www.hepforge.org/archive/openloops/OpenLoops-1.3.0.tar.gz</a>). If you downloaded the previous version via svn in order to update you can simply run:</div><div class="">./openloops update</div><div class=""><br class=""></div><div class="">This version is the first public release including the tensor reduction library COLLIER (in version collier-1.0) developed by A. Denner, S. Dittmaier and L. Hofer. Using OpenLoops together with COLLIER will further significantly increase the performance of most one-loop amplitudes. In particular its high degree of numerical stability requires a significantly smaller amount of phase-space points to be reevaluated at higher numerical precision. Furthermore, especially the performance of loop-squared amplitudes highly benefits from the tensor integral reduction implemented in COLLIER. </div><div class=""><br class=""></div><div class="">For the moment CutTools remains our default reduction library. However, we recommend to use the COLLIER library everywhere. You can switch to COLLIER setting the OpenLoops parameter preset=2 (for loop-induced processes preset=3 should be used); for example in any Sherpa Run-Card one can set: </div><div class="">OL_PARAMETERS preset 2</div><div class=""><br class=""></div><div class="">Additionally this new release contains various improvements and bugfixes as detailed on our hepforge page (<a href="http://openloops.hepforge.org/log.html" class="">http://openloops.hepforge.org/log.html</a>). </div><div class=""><br class=""></div><div class="">Users with access to the public_collier branch should update to the public branch, as public_collier will not be updated.</div><div class=""><br class=""></div><div class="">Best regards,</div><div class="">Jonas, Philipp and Stefano</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">P.s.: Please register to our mailing list (<a href="https://www.hepforge.org/lists/listinfo/openloops-announce" class="">https://www.hepforge.org/lists/listinfo/openloops-announce</a>) in order to receive future release announcements. </div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div></body></html>