Physics

Exclusive production processes at hadron collider are something magical. You direct two trucks at 100 miles per hour one against the other head-on, and the two just gently push each other sideways, continuing their trip perfectly unaffected, but leave behind a new entity (a cart?) produced with the energy of the glancing collision.  That is more or less the picture. Now think at a hadron collision at the LHC, and we can suddenly talk about subnuclear physics without changing much of it. In exclusive production processes, the two projectiles emerge unbroken from the collision, much like…

800x600 Zero Neutrino Mass Scale in Semi-Empirical Phenomenology      There are definite empirical hints on special kind of neutrino masses. 1) Ratio of neutrino masses to the lightest particle electron mass is very small m-nu/m-e = ~10-6. Hence it seems natural to suggest new physics effect of zero neutrino mass scale. 2) Empirical neutrino solar S and atmospheric A mass squared differences, S = ~7.5x10^(-5) eV^2 and A = ~2.5x10^(-3)eV^2, are small and may be considered as perturbation effects that split the primary threefold degenerate zero neutrino masses. 3) That…

Okay, this one was not about the umpteenth statistical fluctuation, hopelessly believed by somebody to be the start of a new era in particle physics. It's gotten too easy to place and win bets like that - the chance that the Standard Model breaks down due to some unexpected, uncalled-for resonance is so tiny that any bet against it is a safe one. And indeed I have won three bets of that kind so far (and cashed 1200 dollars and a bottle of excellent wine); plus, a fourth (for $100) is going to be payable soon. No, this one was a rather more interesting bet, connected to the ability to predict…

After decades of theoretical studies and experimental measurements, forty years ago particle physicists managed to construct a very successful theory, one which describes with great accuracy the dynamics of subnuclear particles. This theory is now universally known as the Standard Model of particle physics. Since then, physicists have invested enormous efforts in the attempt of breaking it down. It is not a contradiction: our understanding of the physical world progresses as we construct a progressively more refined mathematical representation of reality. Often this is done by adding more…

Expectations are rising for the 2016 run of the Large Hadron Collider. The machine has restarted colliding protons in the cores of ATLAS and CMS, where finally the reality of the tantalizing 750 GeV diphoton bumps seen by the two experiments in their Run 1 and 2015 data *will* be assessed one way or the other. The flurry of papers discussing possible interpretations of the observed effect, first reported last December during a data jamboree at CERN, has slightly reduced in intensity but is still going rather strong in an absolute sense. Over 300 phenomenological interpretations have been…

Funny how the internet gives you access to information on your own stuff before you know it. The book I have written, "Anomaly!", is still in production (we have not yet even finalized the book cover), and yet you can even apparently buy a copy already, at the World Scientific site. What is funny is that I discovered the page with the book data by chance, browsing through other books to get inspiration!So if you go to the World Scientific site and click on "particle physics" you can get a list of 800 or so titles, and one of them leads you to this page. In it you can read the description of…

My book "Anomaly! - Collider Physics and the Quest for New Phenomena at Fermilab" is in production at World Scientific, with an expected publication date somewhere in August or September. I have explained what this work is about in previous posts, but maybe what I can do here is to just paste here the few lines of description that have been put together for the back cover: From the mid-1980s, an international collaboration of 600 physicists embarked on the investigation of subnuclear physics at the high-energy frontier. As well as discovering the top quark, the heaviest elementary particle…

It's been a while since the last time I talked about myself in this column. I think that a blog must contain personal information to be interesting - otherwise why sticking around, when there's tons of good (yes, also bad) information in the web ? But here you can get some particle physics information mixed in with things that, although you need not know or care about, it's fun to share and comment on. Or at least I hope it's so, for the few of you who read this. So, where to take it from - I could tell you about the first six months of AMVA4NewPhysics, the European "Initial Training Network…

Long-time readers of this blog know that one of the recurrent topics has always been the precision measurement of the top quark mass. The reason for this is at least three-fold. One, I started my career in experimental HEP with searches and measurements of the top quark properties, and the mass was one of the parameters I spent quite some time working on.  Two, I do believe that the top quark mass is outstandingly interesting in a varied landscape of standard model measurements. The top quark is a unique particle - the heaviest-known elementary fermion, or if you prefer the heaviest…

By Gabriel Popkin, Inside Science -- When leaders of the Laser Interferometer Gravitational-wave Observatory, or LIGO, announced in February the first-ever direct detection of a gravitational wave, astrophysicists Scott Ransom from the National Radio Astronomy Observatory and Andrea Lommen at Franklin and Marshall University in Lancaster, Pennsylvania, had mixed feelings. On the one hand, it meant that the team they and others lead, which searches for gravitational waves using radio telescopes aimed at special stars called pulsars, would not score the first detection. "We loved the idea of…