Physics

A short post today, to mention the latest issue of the CMS Times, a online publication with news from the CMS experiment at CERN's Large Hadron Collider. The CMS Times is always informative and a good resource, but I usually forget to check it due to chronic shortage of CMS time in my agenda. This time, however, I had been warned beforehand that I would find something especially interesting -at least from a personal perspective: an interview with a friend, Natalie Heracleous, who is finishing her Ph.D. in Aachen, Germany, working on a CMS data analysis. It is always important to get the…

White Dwarfs Fancy a trip to Sirius?  This is what you might see as you are approaching your destination. (Picture courtesy NASA/ESA, via the Hubble project.)  Sirius is a multi-famous star, one of its claims to fame being the discovery of a companion.  Wilhelm Friedrich Bessel first postulated an invisible companion to Sirius A from observing a wobble in its motion, and the star itself was observed about 20 years later, while testing what was then the world’s largest refracting telescope, located in Illinois. Actually, the ‘Pup’ (as it is affectionately…

For the unpopular cutting edge, there is no book with the answers at the back. This post will need to suffice for the snarky puzzles at the end of my previous posts. I am a playful snark, not a caustic one. I used to teach retarded citizens how to add. [clarification: while paying for 1 year of math grad school in Bloomington, Indiana, I volunteered an hour a week for a year at a local center.] I am that patient with myself, and will be so with you. Physics discussions can devolve into that 6 year-old boy fighting kind of groove (hi Sascha!). Since this is research, we do have a chance to…

In the comments thread of one of the posts I wrote recently, where I discussed the new tentative signal of a new jet-decaying particle discovered by the CDF collaboration in their data, a reader asked me if hadronic signals of single vector bosons had been seen before by CDF. This question is very much to the point, and its answer is actually not trivial, so I believe it constitutes an excellent topic for an independent post. Mind you, I am sure I wrote more than once in the past about the general topic of reconstructing jet-decaying resonances in hadron collisions, but maybe here we can…

In my post about the new CDF signal of a mysterious new resonance decaying to jet pairs, there is an active comments thread. I posted there a graph crafted by Tommaso Tabarelli de Fatis, a CMS collaborator, who picked the CDF data and simulation and scaled the energy scale of the latter up by a few percent, showing that the agreement of simulation and data was better, and that the bump at 145 GeV could be explained away this way. Below you can see the result of scaling the jet energy scale up by 4% (the jet energy scale is bumped up by just scaling the dijet mass; this is in principle…

Given the wide interest (about 20k readers in a day) that the new article by the CDF collaboration has attracted (see my original post here), I think I should collect in a separate post some auxiliary information, concerning past searches which might have been sensitive to such a signal in the past. First of all, there is the DZERO search for WW/WZ semileptonic decays, which produced the first evidence for those processes at a hadron collider. I described that analysis in some detail in a post in my QDS blog three years ago. Below you can see the money plot from that analysis: the dijet mass…

UPDATE (4/7): I posted a link to a nice animated GIF which shows the (approximate) effect of scaling up the MC/data jet energy scale factor on the CDF new particle signal. See here.UPDATE (4/7): I added some considerations on the tentative CDF signal in a separate post today (4/7). You can find there a comparison with older semileptonic diboson searches at CDF and DZERO. UPDATE (4/6): Okay, I won't wait 5PM FNAL time after all, since I see that other online resources are already discussing it -including the New York Times online, which quotes the co- CDF spokesperson, Giovanni Punzi. I will…

Mysterious Symmetry between Destruction and Growth asked “How on earth does blowing stuff up violently constrain unrelated growth mechanisms? This is the mystery.” In the science of ultra cold Helium droplets of nanometer sizes, there exists a simple, widely known formula, which basically states that the sizes of such droplets obey an unexpected symmetry. This is possibly significant for many similar statistical processes, say during earthquakes or on the stock market. It would be astonishing if Helium droplet physics could investigate this general phenomenon that may hold in quite different…

Rocket science deserves its reputation as a difficult subject to approach. Relativistic rocket science is scarier still. If one tries to take this difficult, scary subject, and apply it to the way the biggest masses in all the Universe move, wouldn’t that be crazy? No, this idea is something that could get you certified. If you don’t know the difference between crazy and certified, well, neither did I before my 2 week vacation at Boulder Community Hospital. That story is too long to tell now.[click or skip the reading of the content of this blog] Newton’s law of gravity is broken. It has…

I have recently dusted off an algorithm I had invented eight years ago, one I dubbed "Hyperball algorithm". It might come handy for predicting the b-tagging rate in CMS events with jets, for an analysis I am thinking of doing. Since saying more would violate a dozen rules so let's leave it at that, and let me instead describe the old idea... Just for fun. Predictions for the Higgs at the TevatronEight years ago the Tevatron was the only player of the Higgs hunting game. LEP II had just left the scene with its 1.7 sigma indication that something might be cooking at a tentative mass of about…