In grand unified theories of the SU(5) or SO(10) type, there is a mass relation predicted between the electron and the down quark, the

muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of , but with a much greater mass. It is classified as a lepton. As wi ...

and the

strange quark The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons ( ...

and the tau lepton and the bottom quark called the Georgi–Jarlskog mass relations. The relations were formulated by Howard Georgi and

Cecilia Jarlskog Cecilia Jarlskog (born in 1941) is a Swedish theoretical physicist, working mainly on elementary particle physics. Jarlskog obtained her doctorate in 1970 in theoretical particle physics at the Technical University of Lund. She is known for her ...

. At GUT scale, these are sometimes quoted as: :

m_ \approx \frac m_

m_ \approx 3 m_

m_ \approx m_

In the same paper it is written that: :

m_ \approx \frac m_d

m_ \approx \frac m_s

m_ \approx \frac m_b

Meaning that: :

m_d \approx 9 m_e

error = 5\%

m_s \approx m_

error = 21\%

m_b \approx 3 m_

error = 26\%

References

Grand Unified Theory {{particle-stub