Physics

This week I am in Warsaw, where I attend the XI workshop on particle correlations and femtoscopy. I am actually here to give a seminar on statistical methods in particle physics next Thursday, but of course I am also going to try and deepen my understanding of the field of investigations of heavy ion collisions. Jan Pluta, one of the old-schoolers of the field, gave an introductory talk this morning. It was titled "A brief history of femtoscopy and particle correlations - a personal view". I am reporting below some impressions from his presentation. What is femtoscopy ? Jan started by warning…

If you are into Nuclear Physics there is very good chance you know about nuclear electromagnetic moments. Actually, nuclear electromagnetic moments has been the field of my specialty from the beginning of my scientific career. This is also why my blog in science20.com was named "Moment Zero" and not because there was some zero-time singularity I broke into writing about scientific stuff (not that I have been very active in here either!). The term nuclear electromagnetic moments 90% of the time refer to the magnetic dipole and the electric quadrupole moment. Each of these physics observables…

Is there a battle between astrology and science? The law of gravity is readily recognized and easily tested.  The force that gave rise to the expression, "whatever goes up must come down" has indeed undergone extensive scientific testing and is largely considered to be one of the most fundamental forces in all of nature.  The very pull of it can be felt as you read these words as you are held to your chair or the floor rather than floating around like a helium balloon.  Given this, is it possible for the gravitational forces from the planets to give rise to meaningful…

Recurrently, uninformed journalists re-discover the h-index and decide to create their own list of the "top scientists" in their country. The most zealous also draw some summary statistics from the list, and then venture to speculate wildly about it. Alas, it's a pattern I've seen a few times now. The latest is an article which somebody posted on my Facebook column. It is uninteresting to see what conclusions are drawn from the graphs and lists published there, as the data are quite incomplete - in the h-index-ordered list of Italian researchers I do not appear, for one, but similarly do not…

As I am spending my time these days selecting candidates for early-stage researcher positions in the EU network I am coordinating, I am reminded of my own experience as a participant to job interviews from the other side of the table. The text below tells the story of my interviews for a post-doctoral position in 1998. Enjoy!  ----           After the 1998 ICHEP conference I was invited to describe my search for Z->bb decays at seminars which were held in rapid succession at Michigan State University, Duke University, Harvard University, and the…

Discovering possible new forces in nature is no easy task. To discover the secret of gravity, the public thinks it took an apple falling from a tree, but really it took him inventing Calculus. linked to Newton's arguably apocryphal apple experiment has remained anchored in popular culture. In January 1986, Ephraim Fischbach, Physics Professor from Purdue University in West Lafayette, Indiana, claimed the hypothetical possibility of the existence of a fifth force in the universe and it has spurred a tremendous amount of research in gravitational physics even though its existence, as initially…

  Nonlocality is an inherent natural feature of quantum reality described by its wave function (WF). It shows itself up not only in the widely discussed cases with two or more particles, but also with one spinless particle. The point is that the WF-Collapse (WF-C) is in general a nonlocal phenomenon. Consider for example a one particle plane wave in quantum mechanics: the particle location in one place is a WF-C that replaces the plane wave by a new WF with zero location in all other places. It means simultaneous prediction with confidence of negative search results at any other…

A longtime follower of this blog, Tony Smith, pointed out to me today this arxiv paper published three days ago. In it, CMS data from Run 1 of the LHC are used to speculate that there might be a second Higgs boson hiding in the data at a mass of about 145 GeV. Check out the two graphs that they produce.The first one, shown below, is their own interpretation of the four-lepton invariant mass from CMS data and background in the H-->ZZ--> four lepton final state: And the second which follows is the mass spectrum of photon pairs, again with their interpretation in terms of two bumps for…

Yesterday my 16 year old son surprised me by explaining that he had been taught at school what alpha, beta, and gamma decays are. He had learned a lot, but I was able to add a little more background information to the picture as he asked me what was the neutrino, which his professor had correctly explained was one of the particles emitted in beta decay. With hindsight, my surprise probably comes from keeping my brain inactive and sticking to a rather conservative idea of how sciences should be taught at school; that idea is that understanding physics requires you to have some solid basis in…

The graph below, I hope you'll agree, is significantly cooler and better-looking than the typical data display plots you get from high-energy physics analyses. Colours are bright, graphical symbols are clean, and one grasps the essence of the information quickly once one knows what it is about. So, let me tell you what it is about for starters. The graph is a figure from a CMS search for pair-production of pairs of light neutral particles, call them "a", when the latter in turn decay to pairs of muons. The reaction can thus be written pp -> aa -> μμμμ, so in the final state you have…