5.1 The quark content of the proton is $uud$.
1.3 The antiparticle of the electron $e^{-}$ is the positron $e^{+}$.
6.1 The quark model predicts the existence of baryons and mesons.
6.2 The quark model explains the hadronic spectrum.
9.1 The gauge group of QED is $U(1)$.
2.1 The first particle accelerator was built in 1930 by Cockcroft and Walton.
7.2 The $W$ and $Z$ bosons mediate the weak interaction.
This solutions manual provides a comprehensive guide to the exercises and problems in "Introduction to Elementary Particles" by Griffiths. The solutions are presented in a clear and concise manner, making it an invaluable resource for students and researchers alike.