Recent content by jc09

Ok I think I understand so I could write luminosity as a function of z but it won't really mean anything to me. So if I was to do that would it be the normal definiton for luminosity: dLH0=z+1/2(1-q0)z2+...?

What if K the curvature did not equal zero. What if it could be equal to +1 or -1 does this make a difference. Then I get k=-H2R2 where we are in units of c equals one. Can we then find a luminosity distance as a function of z even though there is empty cosmology

If Lambda=0 though ??

So if I want to get luminosity distance as a function of redshift how would I do that?

H is the Hubble parameter, k is the curvature constant and R is the scale factor.

If had empty cosmology? What would happen if we had no matter or radiation or dark energyand only had curvature? How would this effect luminosity distance? From the friedman equations I get that H2=-k/R2. Is this right?

How can we tell the values of dark matter and mass in the universe when it is say five times its original size?

If the universe was decelarating and then started to accelerate can we calculate when this happened, and if so how can we do this?

Hi I need help to understand Feynman rules for decay for exams. In past paper there is the following question as whether the following are allowed. cc decays to tau++tau-. From What I can see this is possible via the strong force is this correct? The next is cc decays to cu and cu. From...

If a neutron has zero charge and produces a proton charge one and a electron charge -1 and a neutrino charge 0 why does it need a W- to mediate this

In beta decat the u quark fromthe proton and the d quark from the neutron interact to produce a electron and it's neutrino. I'm wondering about the charge conservation of this process because a neutron has zero charge and a proton has charge of 1. How do we end up with a electron charge of -1 at...

So mesons consist of two quark. I am wondering why no stable mesons exist?

Hi I was wondering if someone could help me out. I have been studying TDPT and was wondering how it applies to atomic physics or if someone could give me a example that would be great.

ok thank you for your help

Hi just wondering if anyone could tell me why the Z boson can couple to any standard model particle except forgluons and photons?