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--- 2015:groups:sm:qg [2015/06/04 16:41]
jesse.thaler [Supplemental Jet Shapes]
+++ 2015:groups:sm:qg [2015/06/04 16:51]
jesse.thaler [What is the killer app of quark/gluon enrichment?]
@@ Line 49: / Line 49: @@
   * Enhancing W/Z/t/H in moderately boosted regime (where we can quark-tag the subjets.
+==== Hemisphere quark/gluon definitions in e+e- ====
+  * Consider the case of e+ e- -> q qbar.  Partition event into (thrust) hemisphere, define hemisphere flavor by summing over flavors of hemisphere constituents.
+  * At LO, we can unambiguously define hemisphere flavors.
+  * At NLO, we can also unambiguously define flavor via hemisphere, though there is now a small gluon fraction from gluon recoiling against q qbar pair.
+  * At NNLO, things are more complicated.
+    * Can have soft gluon splitting into q-qbar in different hemispheres, creates IRC safety issue.
+    * One can use a flavored algorithm (BSZ) to define the flavour of two flavor-kt jets
+    * Ultimately, want to define flavor by the Born-level operator contributing to the process.  All subtleties are formally power suppressed.
+==== Flavored Jet Algorithms ====
+  * This is a topic worthy of its own study.
+  * For pp collisions, multiple possible uses of flavored jet algorithms.
+  * One can just run flavor-kT
+  * Or one can run flavor-kT to define flavor ghosts, and run standard anti-kT.
 ===== Physics Issues =====

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