The Physics of Top Quarks

11 September 2012 | By

In the figure, results are displayed from two different ways of investigating the asymmetry in top-quark vs top-antiquark production. One result was produced by the CDF experiment at the Tevatron collider, measuring the difference in rates between the forward and backward hemispheres of the detector. The other one is from ATLAS at the LHC, looking explicitly at the direction of flight of the two quarks. These are compared to several New Physics theories that could create such an asymmetry. The Standard Model prediction is also depicted. Any model covering the area where the horizontal band (ATLAS) and the vertical band (CDF) cross would be a clear candidate to explain the observed asymmetry. So far, the mystery remains...

The 5th International Workshop on Top Quark Physics (TOP2012) will take place in Winchester, UK, from the 16th to the 21st of September. It will gather experts in the field of top quark physics as well as PhD students and will highlight the newest results and topics related to the physics of top quarks. Discovered in 1995, the top quark is the sixth and heaviest of all quarks, and it is the only one with a lifetime short enough to be observed "naked", i.e. it decays before it can undergo any bound state with other quarks. This makes it special, as its properties can be directly inferred by studying the decay products. With such a large mass (this elementary particle is as heavy as a gold atom) it is also an important testing ground in the search for physics beyond the Standard Model (SM) and it is speculated that it might play a special role in the electroweak symmetry breaking mechanism, which is responsible for giving mass to particles. For the same reason, in many theoretical models new heavy resonances are expected to couple mostly to top quarks. Moreover the direct correlation between its angular momentum and that of its detectable decay products allows us to probe new physics indirectly when top quarks are produced.

This year, for the first time, the programme will be evenly balanced between measurement of its production, its decay and its properties and the now vast number of searches for physics beyond the SM in the top quark sector, thanks mostly to the large amount of data collected at the LHC over the last two years. In addition, two summer-school-like sessions are planned, aimed at PhD students. ATLAS results can be expected on improved top quark pair and single top quark cross-section measurements, refined techniques to measure the top quark mass and a large number of results on properties such as spin correlation and charge asymmetry in top quark pairs or the polarization of W bosons from top quarks. Technical discussions on experimental issues, concerning both the detector and simulations, will also take place. Theorists have been invited to contribute to these complex and exciting topics. Finally, a series of talks about the interplay between the top quark and other hot topics, like the Higgs and Supersymmetry, will be given both at the theoretical and experimental level.