{"action":"created","issue":{"url":"https://api.github.com/repos/cms-sw/genproductions/issues/707","labels_url":"https://api.github.com/repos/cms-sw/genproductions/issues/707/labels{/name}","comments_url":"https://api.github.com/repos/cms-sw/genproductions/issues/707/comments","events_url":"https://api.github.com/repos/cms-sw/genproductions/issues/707/events","html_url":"https://github.com/cms-sw/genproductions/pull/707","id":114376358,"number":707,"title":"Wbb cards","user":{"login":"trandbea","id":9938086,"avatar_url":"https://avatars.githubusercontent.com/u/9938086?v=3","gravatar_id":"","url":"https://api.github.com/users/trandbea","html_url":"https://github.com/trandbea","followers_url":"https://api.github.com/users/trandbea/followers","following_url":"https://api.github.com/users/trandbea/following{/other_user}","gists_url":"https://api.github.com/users/trandbea/gists{/gist_id}","starred_url":"https://api.github.com/users/trandbea/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/trandbea/subscriptions","organizations_url":"https://api.github.com/users/trandbea/orgs","repos_url":"https://api.github.com/users/trandbea/repos","events_url":"https://api.github.com/users/trandbea/events{/privacy}","received_events_url":"https://api.github.com/users/trandbea/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":6,"created_at":"2015-10-31T00:21:13Z","updated_at":"2015-10-31T02:24:38Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/cms-sw/genproductions/pulls/707","html_url":"https://github.com/cms-sw/genproductions/pull/707","diff_url":"https://github.com/cms-sw/genproductions/pull/707.diff","patch_url":"https://github.com/cms-sw/genproductions/pull/707.patch"},"body":"Adding cards for Wbb @ LO + up to 2 extra partons. "},"comment":{"url":"https://api.github.com/repos/cms-sw/genproductions/issues/comments/152687325","html_url":"https://github.com/cms-sw/genproductions/pull/707#issuecomment-152687325","issue_url":"https://api.github.com/repos/cms-sw/genproductions/issues/707","id":152687325,"user":{"login":"bendavid","id":4920798,"avatar_url":"https://avatars.githubusercontent.com/u/4920798?v=3","gravatar_id":"","url":"https://api.github.com/users/bendavid","html_url":"https://github.com/bendavid","followers_url":"https://api.github.com/users/bendavid/followers","following_url":"https://api.github.com/users/bendavid/following{/other_user}","gists_url":"https://api.github.com/users/bendavid/gists{/gist_id}","starred_url":"https://api.github.com/users/bendavid/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bendavid/subscriptions","organizations_url":"https://api.github.com/users/bendavid/orgs","repos_url":"https://api.github.com/users/bendavid/repos","events_url":"https://api.github.com/users/bendavid/events{/privacy}","received_events_url":"https://api.github.com/users/bendavid/received_events","type":"User","site_admin":false},"created_at":"2015-10-31T02:24:38Z","updated_at":"2015-10-31T02:24:38Z","body":"Yes, you can do a simple veto to remove the double counting, but it has to be based on the LHEEventInfo directly.  Once that's done, there's no more double counting because the b's from the parton shower will have been removed by the jet matching itself.\r\n\r\nThere's another subtlety here, that if you want to cover as much of the b-content as possible, you shouldn't do\r\nw bb bb\r\nw bb bb j\r\nw bb bb j j\r\n\r\nbut rather\r\nw bb\r\nw bb j\r\nw bb j j\r\nw bb j j j\r\n\r\nThe reason being that there's a strong correlation between the ME flavours and the parton shower.  (And in particular, if you have an event with only 1 b quark at matrix element level, then it means there is an initial state b, and you will get at least an additional soft b from the parton shower ~100% of the time)\r\n\r\n(and For QCD this becomes\r\nbb j\r\nbb j j\r\nbb j j j\r\n)\r\n\r\nNote that the above argument does not apply to the 4fs case, because in that case there is no initial state b (and in fact the single b case is impossible, except in the W case from off-diagonal ckm couplings)\r\n\r\n"}}