Physics – High Energy Physics – High Energy Physics - Phenomenology
Scientific paper
2011-10-17
Physics
High Energy Physics
High Energy Physics - Phenomenology
15 pages. V2: several minor improvements, new benchmark, comments and references added
Scientific paper
We propose to measure the threshold lepton asymmetry, that is the forward-backward asymmetry of the charged lepton in ttbar events near the production threshold. At threshold top quark pairs are produced in an s-wave. Angular momentum conservation then implies that the top spins equal the spin of the initial state which - in the case of quarks - is uniquely fixed by the chirality of the initial quarks. Thus measuring final state top spins determines the chirality of the quarks which produced them. Information about the top spins can be extracted by measuring the angular distribution of the charged lepton in semileptonic or dileptonic decays of the top pair. One such distribution, the threshold lepton asymmetry, vanishes in tree-level QCD but is non-zero if new physics modifies the relative contribution of right-handed and left-handed quarks to top pair production. This is interesting because realistic models addressing the anomalous ttbar asymmetry have chiral couplings to light quarks. Models with identical ttbar asymmetries at the Tevatron can be distinguished by their threshold lepton asymmetries which range between plus and minus 25% in realistic models.
Falkowski Adam
Perez Gilad
Schmaltz Martin
No associations
LandOfFree
Spinning the Top does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Spinning the Top, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spinning the Top will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-289194