The authors measure the branching fractions of the [psi](2S) meson to the leptonic final states e[sup +]e[sup -] and [mu][sup +][mu][sup -] relative to that for [psi](2S) [yields] J/[psi] [pi][sup +][pi][sup -]. The method uses [psi](2S) mesons produced in the decay of B mesons at the [Upsilon](4S) resonance in a data sample collected with the BABAR detector at the Stanford Linear Accelerator Center. Using previous measurements for the [psi](2S) [yields] J/[psi] [pi][sup +][pi][sup -] branching fraction, they determine the e[sup +]e[sup -] and [mu][sup +][mu][sup -] branching fractions to be 0.0078 [+-] 0.0009 [+-] 0.0008 and 0.0067 [+-] 0.0008 [+-] 0.0007 respectively.

Widely regarded as a classic in its field, Constructing Quarks recounts the history of the post-war conceptual development of elementary-particle physics. Inviting a reappraisal of the status of scientific knowledge, Andrew Pickering suggests that scientists are not mere passive observers and reporters of nature. Rather they are social beings as well as active constructors of natural phenomena who engage in both experimental and theoretical practice. "A prodigious piece of scholarship that I can heartily recommend."—Michael Riordan, New Scientist "An admirable history. . . . Detailed and so accurate."—Hugh N. Pendleton, Physics Today