29,788 reputation
33994
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 5 months
seen 3 hours ago

Experimental nuclear and particle physicist. These days I'm teaching, but I've spent a lot of time on nucleon structure in fixed target electron scattering and neutrino oscillations using reactors and beam sources.


Apr
9
comment Could a tetraquark $q \bar{q} q \bar{q}$ be colorless?
Tetraquarks fit just fine in the standard model and have been sought for a long time. They are neither baryon nor meson, but they are still hadrons. (I suppose the definition of "meson" might be extended to cover this case, but pentaquarks---if found for real---would call for a re-think.)
Apr
9
comment Does it really make sense to talk about field lines?
While I discourage people from talking about "field lines" because I see students confuse themselves that way, the construct can be made mathematically equivalent to a vector field that is divergenceless except at charges. So this becomes a questions about pedagogy.
Apr
8
comment Does a current carrying wire produce electric field outside?
Link-only answers are bad answer. Stack Exchange sites seek to be repositories of good questions with good answers, not link farms.
Apr
8
comment multibody problem and determinism
Not having a closed-form solution is not the same as not having a unique future.
Apr
8
comment Resultant wave in the Michelson-Morley experiment
I am having a hard time understanding what is being asked here. The device is an interferometer, but they don't have any particular expectation about the initial state of interference (because they can't tune the length of the arms to the requisite precision). Instead they have an expectation about how the state of interference will change as they rotate the apparatus. So, what was the question?
Apr
8
comment Where can I find the list of the planetary motion equations?
The polar form is usually $\alpha/r = 1 + \epsilon \cos \theta$ (or $\alpha/r = 1 + \epsilon \cos (\theta + \delta)$) to control at what angle the pericenter lies.
Apr
7
comment Polarizing virtual photons to make fusion easier?
I think that you have not considered the size scale. TO fuse the nuclei must approach to distances several orders of magnitude smaller than the size of an atom. So what do you propose to make the polarizer from?
Apr
7
comment Pion decay in particle physics
Consider parity and angular momentum, too.
Apr
6
revised Apparent velocity of an approaching object
stick in the missing factors of $c$
Apr
6
comment Apparent velocity of an approaching object
Well, I've been a little sloppy in a way that makes sense to particle physicists (we live in a $c=1$ world). I'll be explicit.
Apr
6
answered Apparent velocity of an approaching object
Apr
6
comment Orbital motion with varying radius
You are trying to work the problem the hard way. Neglecting external forces on the body, the energy and angular momentum of the system are conserved and applying these principles is often the easiest way to understand specific questions about orbits. If that won't cut it you generally have to perform the full solution.
Apr
6
comment Orbital motion with varying radius
Any text called "Classical Mechanics" or "Classical Dynamics" should have it. I use Marion&Thornton at the upper-division level and learned from Goldstein in grad-school.
Apr
6
comment Why does a cup with 100 g water float when placed on another cup with 50 g of water?
@quantum To see why the "displaced" water doesn't actually have to be present, cut the outer cup at the height is will obtain once the inner cup is floating and then fill it completely. As we lower the inner cup, water will spill over the outer rim until it floats. If we capture the spill it will have a mass of 100g (from the weight of displaced water version of Archimedes principle). If we now remove the inner cup there is only 50g of water left, but we can surely "un-remove" it and so we are confident that it will float in only 50g of water as long as those 50g are properly confined.
Apr
6
comment Orbital motion with varying radius
The reason introductory textbook only look at the circular case is the more difficult math needed for a complete answer to the non-circular case. We usually teach the full version in an upper-division course that assume the students have had both calculus and differential equations. Some of the relationship from the circular case still hold absolutely (equal area AKA the conservation of angular momentum), other apply only locally and still others are must be modified.
Apr
5
comment Are there any QM effects where charged particles are not intimately involved?
Neutrinos carry weak-hypercharge.
Apr
5
revised Unitarity of PMNS matrix
edited tags
Apr
5
answered Unitarity of PMNS matrix
Apr
4
comment Energy dependent cross sections for neutrons
This kind of data is most often accumulated in ENDFs, which are intended for computer consumptions, but can be read by a sufficiently persistent human. Many sources.
Apr
3
awarded  Enlightened