A Quantum Diaries Survivor

One of the nice things about the 2012 discovery of the Higgs boson is that the particle has been found at a very special spot - that is, with a very special mass. At 125 GeV, the Higgs boson has a significant probability to decay into a multitude of different final states, making the hunt for Higgs events entertaining and diverse.

Exotic baryons, what are they ? But first of all, what is a baryon ? Well, it depends whom you ask the question to. In the context of the static quark model, a baryon is a particle composed of a triplet of quarks, as opposed to a meson, which is a particle composed of a quark-antiquark pair. But the quark model is fifty years old, and nowadays we know better: baryons and mesons do not just contain a triplet or a duo of quarks; they are in fact a soup of quarks and gluons. What is still true is that their intrinsic properties are distinguished by the _valence_ quarks they contain.

The 13 TeV data from LHC collisions taken this summer is quickly going through analysis programs and being used for new physics results, and everybody is wondering whether there are surprises in store... Of course that will require some more time to be ascertained.For the time being, I can offer a couple of very inspiring pictures. CMS recorded a spectacular event featuring two extremely high-energy jets in the first 40 inverse picobarns of data that was collected and reconstructed by the experiment with all detector component properly working.

Are you a post-lauream student in Physics, interested in pursuing a career in particle physics, and maybe with interest in advanced machine learning applications, with an eye to a great job after your PhD ? Then this posting is for you.

Well, as some of you may have heard, the restart of the LHC has not been as smooth as we had hoped. In a machine as complex as this the chance that something gets in the way of a well-followed schedule is quite significant. So there have been slight delays, but the important thing is that the data at 13 TeV centre-of-mass energy are coming, and the first results are being extracted from them.

The reported observation of a resonant state of a J/psi meson and a proton in the decay of the Lambda_b baryon by the LHCb collaboration, broadcast by CERN today, is a very intriguing new piece of the puzzle of hadron spectroscopy - a topic on which many brilliant minds have spent their life in the course of the last half century.

The CERN Director General Rolf Heuer issued the following statement today, reporting the discovery of exotic pentaquark states by the LHCb collaboration:Geneva, 14 July 2015. Today, the LHCb experiment at CERN’s Large Hadron Collider has reported the discovery of a class of particles known as pentaquarks. [...] 

Working as an experimental particle physicist in a large scientific collaboration, such as the 3000-strong CMS experiment at the CERN LHC, is a (not too uncommon) privilege, for several reasons. One of those reasons is of purely numerical kind: the number of publications that bear your name grows by the day, and may reach four-figure values in the course of a couple of decades (I am about to cross that point with my publication list, in fact). But what value do those thousand articles have for the sake of assessing your value as a scientist ? Very little, indeed, and in fact all the selection to which I have participated in my career required one to specify one's specific contribution to all the papers one wished to boast about.

When you create an energetic collision between two protons, as the Large Hadron Collider does at large rates and very high energy, the question is what is the chance that a rare process is generated. In the quantum world, everything that is possible is also mandatory - but it happens with a probability that is sometimes very hard to calculate. 

I was saddened today to hear of the death of David Cline. I do not have much to say here - I am not good with obituaries - but I do remember meeting him at a conference in Albuquerque in 2008, where we chatted on several topics, among them the history of the CDF experiment, a topic on which I had just started to write a book. Perhaps the best I can do here as a way to remember Cline, whose contributions to particle physics can and will certainly be better described by many others (for example,

The Marie-Curie network I am coordinating, AMVA4NewPhysics, is going to start very soon, and with its start several things are going to happen. One you should not be concerned with is the arrival of the first tranche of the 2.4Meuros that the European Research Council has granted us. Something more interesting to you, if you have a degree in Physics or Statistics, is the fact that the network will soon start hiring ten skilled post-lauream researchers across Europe, with the aim of providing them with an exceptional plan of advanced training in particle physics, data analysis, statistics, machine learning, and more.

Have you ever seen Venus in full daylight ? It's a fun experience. Of course we are accustomed to see even a small crescent Moon in daylight -it is large and although of the same colour of clouds, it cannot be missed in a clear sky. But Venus is a small dot, and although it can be quite bright after the sunset or before dawn, during the day it is just a unconspicuous, tiny white dot which you never see, unless you look exactly in its direction.