Physics quiz question: interpreting β+ decay Feynman diagram

Physics 205B Quiz 7, spring semester 2016
Cuesta College, San Luis Obispo, CA

This (valid) Feynman diagram depicts the __________ process.
(A) α.
(B) β^–.
(C) β⁺.
(D) electron capture.
(E) γ.

Correct answer (highlight to unhide): (C)

This diagram shows β⁺ decay, where a proton transforms into a neutron, and the intermediate W⁺ particle decays into a neutrino and a positron, as shown by the left-to-right neutrino arrow, and a right-to-left electron arrow (corresponding to a positron--the "β⁺" particle--progressing left-to-right as time progresses).

Sections 30882, 30883
Exam code: quiz07eYE5
(A) : 2 students
(B) : 3 students
(C) : 30 students
(D) : 5 students
(E) : 0 students

Success level: 75%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.60