Recent content by Rick16

This is odd. I checked the masses and they were okay. I now checked them again, and they are not okay. I must have used the wrong mass for something. Sorry about the bother.

This is problem 2.7 from Griffiths' Introduction to Elementary Particles. Here are the two reactions that I am trying to examine: (c) ##\Sigma^0\rightarrow\Lambda+\pi^0## (g) ##\Delta^+\rightarrow p+\pi^0## According to Griffiths' solutions, (g) is possible, (c) is not possible due to...

Yes, that is mine. I just cannot find anything resembling that one among Griffiths' diagrams. Or could it perhaps be this one:

This is problem 2.3 in Griffiths' Introducion to Elementary Particles. I have Griffiths' solutions, otherwise I would be completely lost. Nonetheless, I tried to come up with a solution of my own first. I found only one possibility, which looked ok to me, but it is not even among the 17 ones...

Thank you. I find it always interesting to read recommendations and comments on books. I noticed that Susan Rigetti has chosen the exact same four basic undergrad texts that I have chosen and that she has marked them as essential: Taylor, Schroeder, Griffiths, and Griffiths. I guess I am not on...

Thanks a lot. This is a derivation that I can follow. For physics purposes it is of course much easier to look up the zeta function and tweek it so that it fits my series. But it is nice to see how this all comes about.

That's why I decided to use an online calculator. I just thought that there might be a simple, straightforward way to solve this. Your demonstration with the zeta function is quite instructive and comes pretty close to the straightforward method that I was looking for, provided that I know the...

Thank you for your detailed answer. It is, however, somewhat over my head. When I asked the question I had no idea that this was such a tricky business.

I obviously don't need it in this case. I will need it for similar questions that may come up in the future.

So apparently there is no straight forward algorithm for this. I will look for an online calculator then.

I have been working through problem 2.7 in Griffiths' QM book. Everything is pretty much clear, except that at the very end the following sum shows up: ##(1/1 + 1/3^2 + 1/5^2 +1/7^2 +...)## According to the solution, this sum equals ##\pi^2/8##. How can this be determined?

This is very helpful, thanks a lot.

Thank you everybody for your help. It all begins to make sense now. Griffiths even puts the equation ##\nabla \cdot (\frac{\hat r}{r^2})=4\pi\delta^3(r)## in a box. There are 108 numbered equations in chapter 1, only 5 of which are boxed. The other ones are the definition of the nabla operator...

This looks very convincing, but do you really go through all this everytime you are confronted with this kind of situation? Griffiths simply isolates the term ##\frac{\hat r}{r^2}## and then uses the relation ##\nabla \cdot \frac{\hat r}{r^2}=4\pi \delta^3 (r)##. At first, I did not understand...

Should I draw the conclusion that whenever I have a vector field in spherical coordinates with ##r^2## in the denominator, I cannot mechanically apply the above expression for the divergence, and that I should instead try to isolate ##\frac{\hat r}{r^2}##, which then gives me an expression for...