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Today: Particle Seminar @ 4:15pm

Tuesday, February 19, 2013  4:15 PM
Harvard University
Particle Seminar
"Measuring Jet Substructure from the Broadening Axis"
Duff Neill
Jefferson Lab, 453
Refreshments in the high energy theory coffee area, 4th floor Jefferson,
at 4:00.

Many jet shapes (such as angularities) have in the past been calculated from a specific axis, the jet's thrust axis - the direction of the total 3-momentum of the jet. For a wide class of angularities, this is very natural, until soft recoil begins have leading order effects upon the measured angularity. Then it is much more natural to introduce a new axis to measure the jet properties against: the broadening axis. This axis roughly tracks the direction of greatest energy flow. Formally, the axis is defined as the one that minimizes the broadening of the jet - the scalar sum of all magnitudes of the transverse momentum (to said axis) of each particle in the jet. We'll show how to obtain factorization theorems, discuss constraints on jet algorithms, and perhaps some phenomenology.