- Problem Statement
- Assume that quarks are presented in SU(Nc) with a unknown dimension of Nc, and define the rate Rμ of the scattering cross sections between e+e- -> hadrons(here, consider u, d, s, c, b quark) and e+e- -> μ+ μ-. Give out the result of Rμ with Nc. See detailed equations below.

- Relevant Equations
- Rμ = σ（e+e- -> hadrons）/ σ(e+e- -> μ+μ- )

I have already known the cross sections can be presented like this.

σ（e+e- -> hadrons）∝ Σ eq^2 & σ(e+e- -> μ+μ- ) ∝ e^2,

where eq is the charge of a certain quark(u, d, s, c or b)

But I don't know the relationship between Nc and eq.

(This is my first time to post a thread. I don't know how to insert a equation typed in LaTex or Word, so it may be a little tired to read...

I'm so sorry about that and thank you for help!)

σ（e+e- -> hadrons）∝ Σ eq^2 & σ(e+e- -> μ+μ- ) ∝ e^2,

where eq is the charge of a certain quark(u, d, s, c or b)

But I don't know the relationship between Nc and eq.

(This is my first time to post a thread. I don't know how to insert a equation typed in LaTex or Word, so it may be a little tired to read...

I'm so sorry about that and thank you for help!)