Physics

A new paper by Davison Soper and Michael Spannowsky has been sent to the Cornell preprint ArXiv last week. It proposes a new technique to reconstruct the decay of heavy particles within hadronic jets, and shows how this can improve the sensitivity to heavy new particles by studying in particular the case of a heavy Z' boson decaying to boosted top quark pairs. I believe the technique is very interesting and I will try to give a few impressions of it here; before I do, let me introduce the topic for outsiders. The search for heavy particle decays into hadronic final states is a fascinating…

Yesterday I visited a high school in Treviso, a small centre in north-west Italy. The students of the last two years participate in a program called "masterclasses" which includes lessons on particle physics and astrophysics and a visit to the department of Physics in Padova, where they will be taught how to distinguish particle decays using real LHC data. My lesson was a short story of particle physics, starting from Thomson and Rutherford and ending with the Higgs boson discovery and what may exist beyond. The about 100 students seemed to follow my lesson with interest, although it was…

First principles are calculations that rely on established mathematical laws of nature without additional assumptions or special models. But when it comes to the early universe, what are those first principles? We're talking really ab initio - "from the beginning" - as in from the beginning of time onward.   In the beginning, the cosmos experienced rapid inflation, electrons and protons floated free from each other, the universe transitioned from complete darkness to light, and enormous stars formed and exploded to start a cascade of events leading to our present-day universe. Milos…

On January 25th 1996 the CDF collaboration submitted for publication to Physical Review Letters  the result of their measurement of the rate of jet production as a function of jet transverse energy, performed on 20 inverse picobarns of data collected by the experiment in the 1992-93 run of the Tevatron collider. That measurement deviated at its high-energy tail from predictions of quantum chromodynamics, suggesting that the underlying model -and most likely, the parton distribution functions (PDF) which describe the probability of finding partons with given fractions of their parent…

Black holes are all the rage these days, with theorists arguing about firewalls and Hawking's paper being handled by the press in rather improper ways. Meanwhile at the Large Hadron Collider ATLAS and CMS are furthering their searches for microscopic versions of the same objects, which could exist if the energy scale at which quantum gravity effects make themselves felt is orders of magnitude smaller than the place where they ought to be -i.e., at the Planck energy. There is a wide variety of phenomena that could signal the production of black holes in the proton-proton collisions of the LHC…

I received yesterday a copy of the brand-new book by Ilya Narsky and Frank Porter, "Statistical Analysis Techniques in Particle Physics" (Wiley-vch 2014), and I would like to offer here my impressions and thoughts on the material. The book comes in soft cover (I am unaware if a hardcover will also be available any time soon), and is printed on nice and good-smelling acid-free paper. This might look like a detail to you, but a good part of my judgement about a book comes from the way it smells ;-). The book costs $89 at WILEY, and you can get a good preview of the material and sample chapters…

Chapter 10 of the report on the 2013 community summer study held at Snowmass, titled "Communication, Education, and Outreach" is available since Jan 24th in the Cornell ArXiv. It is a 26-pages document describing the importance of outreach activities to foster the development of particle physics, and offering ideas and strategies to improve the communication between scientists and policy makers. This is none other than the problem I have often referred to as the one of "filling the gap" between science and the general media. I think the report is a balanced look at the situation and a fair…

In a paper posted to the arXiv a few days ago Stephen W. Hawking the preeminent expert on black holes argued quite effectively that given what we know about quantum gravity they don't exist. Quantum theory allows for matter and energy to escape from a black hole albeit very slowly, and scrambled up. In fact this process has been known for a very long time and is named "Hawking radiation". His latest argument takes the concept a step farther by getting rid of one of the defining aspects of a classical black hole, the "event horizon." For those of you from Rio Linda, Stephen W. Hawking…

"The most important task at hand is experimental. Based on our considerations of dynamical symmetry breaking through preons and the assumption of universal size for all quarks and leptons, we are led to predict that quarks and leptons have an inverse size of the order of 2-3 TeV. This can be tested by high-luminosity 5-10 TeV machines in the near future by looking for form factors for quarks and leptons and for excess production of lepton pairs in pp or ppbar collisions." Jogesh Pati, "Preons and their implications for the next-generation accelerators", Proceedings of  the third annual…

I must say I feel proud of myself tonight. In Italy a unified procedure to rank candidates to the position of associate or full professor has been launched last year, and I of course participated to the qualification by sending a documentation of the work I performed and the articles I wrote in the course of my scientific career. With me, thousands of other candidates did the same. Note that as a researcher for the Italian Institute of Nuclear Physics (INFN) I am presently following a career parallel to the one existing in the University. Despite that, in Italy everybody knows that titles…