Physics quiz question: Feynman diagram vertex interpretation

Physics 205B Quiz 7, spring semester 2017
Cuesta College, San Luis Obispo, CA

This Feynman diagram vertex depicts a pion (π) that is __________ charged.
(A) negatively.
(B) neutrally.
(C) positively.
(D) (This vertex is not possible, as it is invalid.)

Correct answer (highlight to unhide): (B)

This Feynman diagram vertex is valid, so tracing the straight line with arrows from left-to-right (the convention used in this class) shows a proton still remaining a proton, so the pion that is emitted must be neutrally charge (π⁰).

Sections 30882, 30883
Exam code: quiz07N4ci
(A) : 4 students
(B) : 16 students
(C) : 6 students
(D) : 0 students

Success level: 62%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.36