This series consists of talks in the areas of Particle Physics, High Energy Physics & Quantum Field Theory.
Astrophysical observations suggest that the majority of matter in the Universe is made up of novel Weakly Interacting Massive Particles (WIMPs). Such WIMPs are often predicted by extensions to the Standard Model. Efforts have been underway for more than two decades to detect WIMPs directly in detectors on earth. The challenge is great because of the small energies involved and the low interaction rates. The field has been driven by progress in detectors able to identify radioactive backgrounds.
Can we learn about New Physics with astronomical and astro-particle data? Understanding how this is possible is key to unraveling one of the most pressing mysteries at the interface of cosmology and particle physics: the fundamental, particle nature of the dark matter.
Astrophysical observations of the structure of galaxies and clusters are no longer simply proving the existence of DM, but have sharpened into a discovery tool probing the particle physics of dark matter. I discuss small scale structure anomalies for cold dark matter and their possible implications for dark matter physics, such as the existence of forces in the dark sector. New results on cluster scales provide a new important handle for constraining dark matter's particle interactions.
As an experimentalist involved in the search for physics beyond the Standard Model at the LHC, one must choose carefully which signatures to pursue. While theoretical guidance in identifying well motivated gaps in the coverage of “natural” BSM extensions is an important ingredient in this choice, unexplored territory is often unexplored for a reason, namely that there are likely non-trivial (“tricky”) experimental difficulties. One must thus consider the risk (time) vs. reward (discovery) in deciding what to pursue.
The presence of an instability in the Standard Model Higgs potential may have important implications for inflation and the viability of our Universe. In particular, if the Hubble scale during inflation is comparable to (or larger than) the instability scale of the potential, quantum fluctuations in the Higgs field will lead to the Higgs sampling the unstable part of the potential during inflation. However, to correctly study transitions to the unstable regime and determine the significance for the resulting universe requires addressing a number of subtleties.
With the increase of the center-of-mass energy from 8 TeV
to 13 TeV for LHC Run 2, the probability for boosted topologies will
become even higher than in Run 1. This also comes with a large
increase in pileup from the increased luminosity. This talk
investigates the state of the art of boosted algorithms and grooming
techniques, addresses shortcomings and possible improvements, and
discusses hot-topic items that will be interesting early on in Run 2.
I will talk about the physics of models in which dark matter consists of composite bound states carrying a large conserved dark “nucleon” number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. >~ 10^8, may be synthesised, with the number distribution taking one of two characteristic forms, which interestingly are broadly independent of initial conditions.
It is not known how to explain the excess of matter over antimatter with the Standard Model. This matter asymmetry can be accounted for in certain extensions of the Standard Model through the mechanism of electroweak baryogenesis (EWBG), in which the extra baryons are created in the early Universe during the electroweak phase transition. In this talk I will review EWBG, connect it to theories of new physics beyond the Standard Model, and show that in many cases the new particles and interactions required for efficient EWBG can be discovered using existing and expected data from the LHC.
I will describe a new collider object we have termed emerging jets.
These can arise when there is a confining dark sector connected to the
Standard Model by a TeV scale mediator, a scenario that is well
motivated by dark matter considerations. The signature of an emerging
jet is O(10) displaced vertices inside the jet each with different
impact parameter, and a small number of prompt tracks. I will describe
strategies that can be used to discover emerging jets even if they
have very small cross sections.
We introduce and systematically study an expansive class of "orbifold Higgs" theories in which the weak scale is protected by accidental symmetries arising from the orbifold reduction of continuous symmetries. The protection mechanism eliminates quadratic sensitivity of the Higgs mass to higher scales at one loop (or more) and does not involve any new states charged under the Standard Model.