Download or read book Measurements of the Tau Mass and Mass Difference of the Tau+̂ and Tau-̂ at BABAR. written by and published by . This book was released on 2009 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present the result of a precision measurement of the mass of the? lepton, M{sub?}, based on 423 fb−1 of data recorded at the?(4S) resonance with the BABAR detector. Using a pseudomass endpoint method, they determine the mass to be 1776.68 ± 0.12(stat) ± 0.41(syst) MeV. They also measure the mass difference between the? and {tau}−, and obtain (M{sub {tau}+} - M{sub {tau}−})/M{sub AVG}{sup {tau}} = ( -3.4 ± 1.3(stat) ± 0.3(syst)) x 10−4, where M{sub AVG}{sup {tau}} is the average value of M{sub {tau}+} and M{sub {tau}−}.