Recent content by IAN 25

Right PeterDonis, thanks for that and the link; it answers my query.

Perhaps I am not making myself very clear. My question is about those virtual photons which might travel a long distance / exist for a long time. According to Chalnoth (above) and the Wikipedia entry on 'virtual particles', they start to behave more like their real counterparts. So, I was...

Since discussing Hawking Radiation (two years ago!) I have re-visited the subject of virtual particles in another context. Given what you say, above, and that the range of a photon is in theory, infinite, what happens to a virtual photon mediating an interaction between two electrons (or protons...

Of course, yes. Right , thanks.

If they move relative to each other, I can see there will be more kinetic energy in the C.M. frame. However, the sum of their momenta will be zero in that frame. So, the expression (E1 + E2 )2 - (p1 + p2)2 will not change as a result will it? Since, the momentum term is zero. Or is the rest...

I did read an article featuring this in the UCL Physics department Annual Departmental Review in the year concerned.

Yes that is an interesting example. In you original expression, it is clearly the term 2(E1 E2 - p1. p2 which provides the range of kinetic energies of the pions observed either side of the peak in the laboratory frame.

Got it! I can follow the algebra but the two worded sentences of physics (mfb) add clarity. Thank you both.

I still don't see why this gives a range of rest mass energies. That's the point I am trying to understand - the continuous range?

To me invariant mass means invariant, whether its a sum for several particles or not; the masses have discrete values and E2 -(pc)2 = m2c4 for each particle (or for a sum of particles) which as I understand it, is a scalar invariant - which has the same value in all inertial frames, does it...

Thank you. Okay, I understand what the invariant mass of the system is - but if it is the sum of the invariant masses of the (two?) pions that is plotted, why is there a continuous range?

The interaction p + π- → n + π- + π + may proceed by the creation of an intermediate 'particle' or resonance called a rho. This can be detected as a peak in the plot of invariant rest mass energy of the emergent pions versus frequency of pions observed. My question is quite simply, invariant...

Thanks for taking the trouble to reply to me. I can understand some of that but I will read further as you suggest. Thank you.

Okay, thank you very much for that.

Thank you Vanhees, I am familiar with the expressions above; the first being the Fourier expansion in terms of the annihilation and creation operators for particles and antiparticles. The second, normalization expressions giving the roots of the K.G Equation. However, your answer is purely...