# 6.8.5 Quarks in Particle Decay Equations

## Balancing Quark transformation equations

• By looking at the transformation of quarks inside the protons and neutrons in beta decay it is possible to analyse the decay of specific quarks inside

#### Beta-minus decay

• In beta-minus decay, one of the neutrons in a nucleus is converted into a proton in a process that may be written as:

n → p + e- • The neutron, n has the quark composition udd
• The proton, p has the quark composition uud
• So the beta-minus decay must involve a down quark converting to an up quark

d → u + e-  Balancing Charge

• The charge on the left side of the equation is - • The total charge on the right side is e + (-1)e + 0 = - e
• So, the decay equation is balanced in terms of charge

#### Beta-plus Decay

• In beta-plus decay a proton is converted into a neutron with the emission of a positron and an electron neutrino in a process that may be written as:

p → n + e+ + v

• The proton, p has the quark composition uud
• The neutron, n has the quark composition udd
• So, the beta-plus decay must involve an up quark converting to a down quark

u → d + e+ + v Balancing Charge

• The charge on the left side of the equation is + • The total charge on the right side is - e + e + 0 = + e
• So the decay equation is balanced in terms of charge

Charge must be conserved in any reaction or decay equation

#### Worked example

The equation for β decay is Using the quark model of beta decay, prove that the charge is conserved in this equation.  ### Get unlimited access

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