Recent content by Severian

Given the current climate for fundamental physics research in the UK right now, you want to avoid it at all costs. Because even if you do get a job as a researcher, you will get no encouragement or support from the government. And the UK scientific community is extremely partisan, political and...

To be honest, I am surprised this got passed the hep-ph censor, since you have no affiliation. A number of comments: 1. You didn't really explain what the '1's are on your fields, except for "each of the above psi functions has some definite number of indices taking the only value gamma =...

Think about the Feynman diagrams which make up the processes. At leading order the 2 jet rate is has two quarks in the final state, while the 3 jet rate has 2 quarks and a gluon. The gluon is radiated from a quark line, so there will be an extra factor of alpha_s.

It is unclear to me whether the original poster is asking how we know that the Planck length is so small, or is asking the much harder question of why is it so small. As to the 'how we know', it is simply a reflection of the observable fact that gravity is an extremely weak force compared to...

The last time I examined a PhD student, I managed to make her cry. I still passed her though. This one I am reading now looks fine.

I have to examine someone for a PhD next week. I just started reading the thesis today.

I think proton driven thorium fission is a really nice idea. No chance of meltdown since it isn't a runaway reaction (it needs to be driven by the proton beam) and waste products with much shorter half-lives. I must admit to initially being put off by it being promoted by Carlo Rubbia, since he...

This was in a talk by John Conway a few weeks ago at Aspen: http://www.physics.ucdavis.edu/%7Econway/talks/Conway-Aspen-2007.pdf It is only a 2-sigma excess (actually 2.1 - you can't put the point in an url), so nothing to get exicited about, and (as someone already said) the excess is too...

The symmetry that QCD is based on is basically a symmetry in relabelling the colors red, green and blue. (More exactly, if you consider red green and blue as directions in the color space, QCD is symmetric under rotations.) Now, obviously swapping the colors will change all of your proposed...

That doesn't really help much because I still don't know how to do \int \sin \left[ 2\pi (x^3+ax^2+bx ) \right] dx or its cosine counterpart.

Yes, of course e^{-x^2} is integrable. Silly me! Some sort of hypergeometric maybe?

I am interested in the integral \int e^{2 \pi i \left( x^3+ax^2+bx \right) } dx Since \int e^{-x^2} dx is non-integrable, I suspect this integral may be too, but I am not so sure because of the exponent being imaginary. Does anyone know? If it is integrable, does anyone have any idea how to...

Last night I had sweet and sour chicken with fried rice. The night before, I had friends round so I cooked a proper meal: a starter of scallops, main course was venison steaks with asparagus and croquette potatoes, followed by sticky toffee pudding. Three nights ago I fried some calves liver...

Any mass term will flip the helicity - that is what mass terms do. So for a massive particle, helicity is not a good quantum number. Think of it this way: the helicity is the spin in the direction of motion, so all I need to do to change the helicity is go faster than the particle. Then the...

I think I have already explained this to you. L&L's analysis assumes non-interacting fermions to simplify the situation for the reader - they are not saying that the fermions must be non-interacting for the PEP to work. I will condeed that the OP's question is ambiguous, and it is feasible...