If a reaction involving hadrons were written at the quark level as ūd + uud → d + X, which of the following could be the quark composition of the unknown last particle X?
A) udc
B) uus
C) uds
D) u
E) cū

Question

If a reaction involving hadrons were written at the quark level as ūd + uud → d  + X, which of the following could be the quark composition of the unknown last particle X?
A) udc 
B) uus 
C) uds 
D) u 
E) cū

Quizplus · Accepted Answer

The total charge in the initial and final states must be the same. The charge of the left side is +4/3 (ūd = -2/3 + 2/3 + 4/3). The charge of the right side is -1/3 + Q, where Q is the charge of the unknown particle X. Since the total charge must be conserved, Q = -1. This eliminates choices A,E and D. Additionally, since there are already two up quarks in the reaction, the unknown particle X cannot have another up quark without violating conservation of baryon number. This eliminates choice B. Therefore, the only valid option is C, uds.

If a Reaction Involving Hadrons Were Written at the Quark