High Energy Phenomenology in the LHC Era

With the advent of the Large Hardon Collider (LHC) at CERN, high energy physics has entered an entirely new phase, in which the elementary building blocks of matter are being studied at TeV energies. Already the first three years of its running have produced the dramatic discovery of a new, possibly fundamental, boson with a mass of roughly 125 GeV, which has been identified as the Standard Model (SM) Higgs. At the same time, a careful analysis of LHC data is being carried out to confront the predictions of various BSM scenarios, challenging theorists to refine their models and identify clear observable signatures within them. Finally, within purely SM physics and in particular its strongly interacting sector, the heavy ion runs conducted at the LHC allow the probing of its Quark Gluon Plasma (QGP) phase at considerably higher energy densities than before. This calls for revisiting the theory predictions made for the SPS and RHIC experiments, and in particular puts the famous claim of the QGP being a strongly interacting, nearly ideal fluid to a quantitative test.

Alongside with the challenges in collider physics, we live in an exciting time also in cosmology and astroparticle physics. The Planck collaboration has now completed its map of the Cosmic Microwave Background of the universe, and the LIGO experiment has recently started its search for gravitational wave signals, possibly opening up a fundamentally new observational window to the early universe. At the same time, recent years have witnessed a dramatic progress in observational astrophysics, as by far the most massive neutron stars to date, with masses of roughly two solar masses, have been observed. This casts an important challenge to theorists working on the properties of nuclear and quark matter, as it should now finally be possible to identify the composition of stellar matter, if only the theoretical predictions for the mass-radius relationship corresponding to different possibilities were accurate enough.

The above topics are examples of the physics questions that the research of the high energy phenomenology project concentrates on. Our hope is that through this broad agenda, we are able to generate an active and communicative research environment that ties together a large number of subcommunities of Finnish high energy physics.