Well, this is just a short personal post about my research. I’m really excited about some of the stuff I’m doing, but the details are still not ready for public consumption. That research is waking me up at night at random times (lets say 3 or 4 in the morning) and then I have trouble going to sleep. In a certain sense, this must be how vampires feel: completely alert and awake at night with a clear vision of what needs to be done and and h0w to do it (this is a typical romanticized version of vampires, which do exist in nature, but look nothing like count Dracula, which is the typical class of vampire that this post refers to).
This wakefulness at night has profound consequences for my days at work. Basically, I’m not getting enough sleep and I walk the corridors with a slight headache and a characteristic lack of brain function during the day. Essentially, the only thing that keeps me separated from being a true zombie is that I’m still technically alive and my body parts are not falling as I shuffle by in the corridors.
Getting a sufficiently high dose of caffeine is not doing the usual trick. So if you see me walking around like zombie: don’t worry. It’ll be fixed during the midnight hours.
That sounds damn exciting. I’ve only lost much of the 5-6 night in my life due to waking up because of the belief that I had just realized something magnificent. None of those ideas has been established yet and there are some good reasons to think that the days still have a creative advantage and enhanced accuracy over the nights.
So be sensible.
Apologies if a little off topic, I was reading
http://arxiv.org/PS_cache/arxiv/pdf/0807/0807.1126v2.pdf
and came across this in section 5:
“but this decay mode suffers from the SM background of the
associated production of a W and two jets, which could spoil a possible Z′ signal with very small mixing angles.”
I had a little difficulty interpreting what is meant by how the w and two jets spoil the Z’ signal. I didn’t know if there was a quick elaboration. Apologize in advance on my ignorance of all the issues regarding resonances, but I’m just curious.
Hi Just learning:
Oi! I didn’t personally write that one phrase, but here is the explanation:
If a Z’ that was produced on shell (in the s-channel) and subsequently decays to two W’s, usually at least one of the W’s is hadronic. So the final signal is W (as identified by an electron or muon and missing energy) plus 2 jets whose energy reconstructs a W plus the fact that there is blurring and uncertainty in the detector, so the jets reconstruction of the W is not too great. So the detector signal to look for is W +2jets. The event would be seen as excess in W+2jets with the 2 jets being around the W mass.
Now, in our model, the Z’ was rather weakly coupled to two W’s (it happened via mixing with Z), so the excess signal is small (tiny).
Turns out that QCD and the standard model produce huge backgrounds for this. If it was just Z bosons off-shell with the ZWW vertex, we know the Z well enough that we might be able to do it by looking for a peak, but throwing QCD in the mix really messes up any estimate for the backgrounds to see such an excess.
p.s.
[youtube http://www.youtube.com/watch?v=BjMiDZIY1bM&w=425&h=349%5D
Just to cheer you up
It did cheer me up. It’s been a while since I’ve had brains.
Incidentally, one of the things I would like you to lose nights over is the explanation of all the existing hints of new physics via the Delta-27 quiver – I hadn’t read this 2001 paper of yours before yesterday, kind of ashamed of this historical coincidence.
Hi Lubos:
Our Delta-27 quiver (if moderately weakly coupled) is in my opinion ruled out by current data (it predicts too many chiral doublets for SU(2) weak): this was already my conclusion in 2002 after thinking about it some more. At the time we wrote this paper this was not obvious to us considering all the Higgsings that had to be done to make it work. This is one of the reasons I started looking into unoriented models: this conclusion of too many doublets is essentially unavoidable in oriented models because of how anomaly cancellation works.
Incidentally, Delta-27 is also used to try to figure out neutrino masses for completely different reasons. I think that has led to the resurgence of the study of this discrete group.
Hi David, thanks, and well, everyone else in the flat braneworlds is using unoriented models, usually intersecting D6 etc. which is what I would normally hear about. But do you know whether e.g. the recent paper by Lüst et al.
http://arxiv.org/abs/arXiv:1104.2302
is affected by the conclusion you made? They kind of “roughly” use your model etc. and make rather specific predictions. But maybe the model is castrated in some way that automatically follows from the orientifolding. If they use a different specific stringy construction of the model than yours, they don’t seem quite explicit about it.
I’m being silly, their newest Luest et al. paper is building on your orientifold paper with Pinansky,
http://arxiv.org/abs/hep-th/0610104
Heh, I am now losing sleep over why I don’t get better answers to my challenges to the IMHO very bad many-worlds interpretation of QM. See for example at Chad’s post at http://scienceblogs.com/principles/2011/06/the_statistics_of_the_highly_i.php. The perplexities of QM have surely caused plenty of lost sleep. I have found that use of l-lysine before bed can ease symptoms of inadequate sleep. In any case I hope your research leads to a fruitful outcome you can be proud of, and not just more going round the mulberry bush. Then it can be tiredness with satisfaction after hard work.
Sorry this is slightly slightly off topic. David or Moshe, please, could you give a qualified answer to this ?: http://physics.stackexchange.com/questions/10754/is-string-theory-a-quantum-theory-of-gravity
Hi guest:
String theory is a theory of quantum gravity: the fluctuation spectrum has particles of spin two and mass equal to zero. Coherent states of these particles give gravitational waves. In this sense it is a quantum theory of gravity: it has quanta associated to gravitational waves. These scatter from other states as expected from gravitational physics.
String theory itself does not yet have much to say about the singularity structure of black holes: our computational tools are not sufficiently well developed to do this. Via dualities other formulations of string theory (like those found in the gauge/gravity duality) might permit one to study what replaces the cherished notion of geometry when it stops working (for example at singularities, but it could happen sooner). This is not understood yet, but there is in principle nothing that indicates that this point of view will fail. We might just face difficult computational hurdles to get there.
Thanks, David!
Hi David
What about topology changes (transitions) at the singularities (e.g at conifold singularities).
Isn’t this a major success of the theory in dealing with singularities?
Hi Giotis:
Indeed, those singularities have been resolved. They only involve space though. We have had very little to say as of yet about the ones that involve time in a fundamental way. These are the ones that appear when we deal with formation and evaporation of black holes.
Crude but interesting
http://physics.stackexchange.com/questions/11029/why-i-like-the-do-data