An infrared-safe jet clustering algorithm invented by Matteo Cacciari takes the reciprocal of a component of this quantity. A parton distribution function gives the probability density of finding a parton at a given value of a component of this quantity. (10[2])The transverse component of this quantity is large for “hard” interactions like (10[1])hadronization (-5[2])and small (10[1])for “soft” interactions. The scattering (-5[1])vector q represents the transfer (-5[1])of this quantity, (10[2])where this quantity (10[1])equals Planck’s constant times wavevector. (10[9])In the analysis (10[1])of scattering (10[3])problems, the center of mass (10[1])frame (10[1])is often (10[1])generalized (10[2])by an inertial frame named the center of this quantity. (10[5]-5[5])Both elastic (10[1])and (10[1])inelastic collisions (10[5]-5[2])obey (10[3]-5[2])this quantity’s (10[4]-5[1])conservation (10[5])law. (10[12]-5[2])For (10[1])10 points, (10[1]-5[1])name (10[1])this (10[1])quantity equal to mass times (10[2])velocity. (10[3]0[1]) (10[13]0[1])■END■