30th November 2011 – Physicists are confident they will soon be able to answer a fundamental question at the LHC: how do particles acquire mass? The simplest answer, the one given in the Standard Model of the fundamental particles, is that a single particle, the Higgs boson, endows the other particles and itself with mass. The Higgs boson does this by means of the "Higgs mechanism", which involves breaking a symmetry that would leave all Standard Model particles massless if it were not broken. However the Higgs boson is not the only way the Higgs mechanism might work.
25th November 2011 – Today we witnessed a landmark LHC first: At the HCP conference in Paris, friendly rivals, the ATLAS and CMS collaborations, came together to present a joint result! This ATLAS-CMS combined Higgs search was motivated by the fact that pooling the dataset increases our chances of excluding or finding the Higgs boson over those of a single experiment. This is the first example of this kind of scientific collaboration at the LHC, and the success of the whole endeavor hinged on a whole host of thorny issues being tackled…
18th November 2011 – Perhaps the most anticipated result of the LHC involves the search for the Higgs boson, the only particle predicted by the Standard Model (SM) that has not yet been seen by experiments. The Higgs boson helps explain how elementary particles acquire mass. If the SM Higgs boson exists it will be produced at the LHC and swiftly decay into various known and well-studied particles, with the dominant decay products depending on the actual Higgs mass. ATLAS and CMS search for the SM Higgs boson using a range of decay products: two photons; two tau leptons; two b quarks; two W bosons; and two Z bosons. Analysing all these channels ensures that the search is sensitive to observing the Higgs irrespective of its mass.
18th November 2011 – I’m writing from the annual Hadron Collider Physics Symposium, which began on Monday in Paris, France. It’s organised jointly by LPNHE and the University of Paris VI & VII, with an excellent location right in the heart of the Latin Quarter. HCP is a fun conference with only plenary talks, which means that I’ve had the chance to attend talks on a wide range of subjects including many quite remote from my usual areas of expertise.
16th November 2011 – If you ask a child to draw a physicist, they’ll usually draw you a disheveled man in a lab coat. But looking around the hundreds of physicists eating lunch at CERN today, I saw many women, only one or two that could be classified as disheveled, and zero lab coats. Yet this image persists.
16th November 2011 – The ATLAS Experiment presented its latest results at the Hadron Collider Physics Symposium 2011 in Paris, France (14-18 November). Many of the most recent searches and analyses are based on more than double the data available at the last big conference in August.
15th November 2011 – It’s not every day you get to explain ATLAS to a group of journalists with just a pop-up book as a prop. But, as some readers might already know, this is no ordinary pop-up book. ATLAS and the LHC leap from the page in incredible detail thanks to paper engineer Anton Radevsky’s wonderful designs. A new edition of the book has just been released in French, so at the end of last month I found myself travelling in to the centre of Paris from Orsay for the press launch.
1st November 2011 – The clock just turned 2:00 a.m., again, on LHC Page One – the machine’s online status viewer – and I’m pondering just how I ended up on the longest shift of the year. I normally love this evening, snuggling under a warm comforter for that extra hour of late-autumn sleep. But, this year, on the very hour we ‘fall back’, I am cuddling with the controls of ATLAS’s 46 meter long muon spectrometer, a bar of chocolate and an extra cup of coffee. So be it.
28th October 2011 – In an amazing year that has exceeded our expectations, the Large Hadron Collider has delivered, and ATLAS has recorded, over 5 inverse femtobarns (fb-1) of collisions. These units correspond to having 3.4 x 1014 or 340 000 000 000 000 total collisions. Most analyses presented at the last major conference (the Lepton Photon Symposium in August in Mumbai) made use of about 1 fb-1, so this is a big jump.
18th October 2011 – A new French edition of the ATLAS pop-up book, Voyage au Cœur de la Matière (Voyage to the Heart of Matter), will be officially launched from the exhibition Entrée en Matière at Paris' Trocadéro on Tuesday, October 25th.