Explain the change of quark character associated with the beta-plus decay and deduce the equation.

First, we can deduce the equation for beta-plus decay in terms of the nucleons. We know a positron, ß+ (antilepton), is produced, so to conserve lepton number an electron neutrino, ve (lepton), must also be produced. As we know this is a nuclear reaction (occurring in the nucleus) it must involve either proton or neutron decay. We can then work out that, to conserve charge, it must be a proton decaying into a neutron as the positron on the right-hand side is positively charged:

p → n + ß+ +ve

Now we consider the quark composition of the proton and neutron. As baryons both must contain 3 quarks. As the up quark has charge +2/3 and the down has charge -1/3 we can use our knowledge of the charge of the proton and neutron to figure out their compositions; uud and udd respectively. Finally, we can see the actual change occurring is an up quark decaying into a down quark:

u → d + ß+ +ve

TF
Answered by Thomas F. Physics tutor

5733 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

A cylindrical specimen of material with diameter 1.5x10^-4 has a breaking stress of 1.3GPa. Calculate the tensile force acting on the specimen at breaking point.


Describe and explain the motion of a skydiver from leaving the aircraft to reaching terminal velocity


The mercury atoms in a fluorescent tube are excited and then emit photons in the ultraviolet region of the elecrtomagnetic spectrum. Explain how the mercury atoms become excited.


What is the function of the control rods in the entire fission reactor proccess?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning