UCL HEP Seminars
Seminars are generally held at 4pm on Fridays in room A1 on the top floor of the physics department
A calendar of all seminars in the Physics Department
is available on the Physics Events Calendar page.
If you use Google Calendar or similar, such as Apple iCal, it is possible to subscribe to this calendar via: XML, ICAL or HTML.
Please send suggestions for topics and/or speakers to Andreas Korn and Lucian Harland-Lang.
03/03/2017 Fady Bishara (Oxford)
The next frontier for Higgs couplings
The LHC experiments have, so far, measured many of the Higgs couplings and found excellent agreement with the minimally-realized electroweak symmetry breaking (EWSB) mechanism in the Standard Model. Nevertheless, there are important couplings that are currently out of reach which test the nature of EWSB and fermion mass generation. This talk will focus on two of them: the charm Yukawa and the hhVV couplings. A measurement of the first would confirm that the 125 GeV Higgs which gives mass to third generation fermions also gives mass the second generation. To this end, I will describe recent ideas to probe the charm Yukawa coupling in particular by using Higgs differential distributions. In the second case, deviations of the hhVV coupling from the SM would signal non-linearity and herald new physics at higher energies. As I will show, double Higgs production in VBF at the LHC can provide such a test at the 20% level by the end of the high luminosity run while a percent level constraint can be obtained at a future circular collider.
10/03/2017 : Edward Daw (Sheffield)
Axions and Axion-Like Particles
In recent years, searches for new physics beyond the standard model have focussed on the electroweak scale, using channels that are reachable in high energy accelerators and through induced interactions of hypothesised electroweak-scale relic particles (WIMPs) in tonne-scale direct search experiments. A second possibility which is scientifically just as well-motivated is that the dark matter consists of much lighter pseudoscalars, called axions, whose origin is in low energy quantum chromodynamics, whose coupling to ordinary matter is feeble because their low mass, and consequently their feeble couplings to other particles, renders them 'invisible' to ordinary accelerator searches. The same feeble couplings mean that axions have very long decay times, so that relic axions generated in the very early Universe may be the dark matter evidenced through its gravitational effects today. I shall survey the field of axion-sector experimental searches. Experiments that look directly for the axion itself attempt to induce dark matter axions to convert into microwave photons in closed electromagnetic resonators. Other experiments identify other by-products of the symmetry breaking mechanism that may have yielded axions; these other by-products are sometimes called ALPs (axion-like particles), and experiments to search for ALPs typically use a 'light shining through a wall' technique. Overall this is an exciting and growing field. I will also discuss some of my own work on axion searches with the ADMX experiment, aimed towards improvements in the sensitivity and search rate of such experiments by means of novel modifications to the resonant detector design.
24/03/2017 : Jose No (KCL)