Physics

The simplified model below shows the reactants and products of a proton–antiproton reaction which produces three particles called pions, each having a different charge.

There are no other products in this process, which involves only the rearrangement of quarks. No electromagnetic radiation is produced. Assume that the initial kinetic energy of the proton and antiproton is negligible.

Protons consist of two up quarks ($u$) and a down quark ($d$). Antiprotons consist of two up antiquarks ($\bar{u}$) and a down antiquark ($\bar{d}$). Each of the pions consists of two quarks.

The following tables provide information about hadrons and quarks.

Table 1: Hadron information

Table 2: Quark charges

(a) Identify the quarks present in the $\pi^-$, $\pi^+$ and the $\pi^0$ particles.

The simplified model below shows the reactants and products of a proton–antiproton reaction which produces three particles called pions, each having a different charge.

There are no other products in this process, which involves only the rearrangement of quarks. No electromagnetic radiation is produced. Assume that the initial kinetic energy of the proton and antiproton is negligible.

Protons consist of two up quarks ($u$) and a down quark ($d$). Antiprotons consist of two up antiquarks ($\bar{u}$) and a down antiquark ($\bar{d}$). Each of the pions consists of two quarks.

The following tables provide information about hadrons and quarks.

Table 1: Hadron information

Table 2: Quark charges

(b) The energy released in the reaction is shared equally between the pions. Calculate the energy released per pion in this reaction.

The Standard Model of matter states that protons are not considered to be fundamental particles because:
(A) protons may spontaneously decay into other particles.
(B) fundamental particles have no charge.
(C) protons can be broken apart in particle accelerators.
(D) protons are a member of the boson family of particles.