Inner space meets outer space: covering the connections between cosmology and particle physics

Date: Saturday, January 25, 2014 - 10:30

Venue: Theoretical Physics, 1 Keble Road, Oxford OX1 3NP

At this event the speakers examined the implications of recent astrophysical experiments for physics beyond the Standard Model, considering the connections between cosmology and particle theory.

The morning began with a preface from Prof Subir Sarkar: Inner space meets outer space: Introduction, an overview of how the known laws of physics have enabled us to reconstruct the evolution of the universe from a hot Big Bang origin and the key questions that are still left unanswered. Click to see the Podcast and the PDF file.

One of these unanswered questions is the nature of the dark matter that dominates the universe and the second talk focussed on both experimental searches and theoretical ideas involving physics beyond the Standard Model. The most ambitious such extension is string theory and the third talk discussed possible novel astrophysical signatures of the new spatial dimensions which are invoked in such a framework. Finally the third talk discussed the recent discovery of very high energy cosmic neutrinos and the exciting prospects that are opened up for probing fundamental physics and cosmology.

Speakers

Felix Kahlhoefer

Darkness visible: the hunt for dark matter

Video podcast Presentation (PDF)

Almost everything we know about the universe has been deduced from observing the skies and measuring the light and other kinds of radiation emitted by cosmic sources. But most of the gravitation matter in the universe seems to be dark. It is likely composed of new relic particles (arising in physics beyond the Standard Model) that do not emit, absorb, or reflect light. To learn about this dark matter, we need radically different detection strategies, which have indeed been developed and improved on in the past three decades. So far, non-gravitational interactions of dark matter remain invisible – but the search has only just begun. Over the coming years, particle colliders, underground detectors and telescopes will reach unprecedented sensitivity. No matter how we first observe dark matter, we will immediately begin to learn about its particle properties. What is its mass? Does it have spin? Does it interact via any of the known forces of Nature or via new, yet undiscovered, interactions? We hope to soon begin to answer these questions and thereby solve one of the greatest puzzles of physics.

Dr David Marsh

String theory on the sky

Video Podcast Presentation (PDF)

The Big Bang has provided us with a cosmic collider through which we may gain observational access to processes far beyond those probed by terrestrial experiments. On the theoretical side, the leading contender for the high-energy completion of particle physics — i.e. string theory — provides compelling arguments for the existence of a large set of spin-0 particles that only couple with gravitational strength interactions and that have masses between 10^5 GeV and 10^18 GeV. Collider experiments cannot detect such particles, but they may leave an imprint in the sky that can be read off from the minute anisotropies of the Cosmic Microwave Background (CMB). X-rays emerging from clusters of distant galaxies may provide additional hints of string theory motivated “dark” sectors of the universe, perhaps indicating the existence of a Cosmic Axion Background (CAB) in addition to the CMB.

Prof Subir Sarkar

Seeing the high energy universe with IceCube

Video Podcast Presentation (PDF)

The IceCube Neutrino Observatory buried in the icecap below the South Pole has recently detected 28 events initiated by neutrinos with energies extending up to a thousand times higher than the reach of terrestrial accelerators. The are very unlikely to have originated from cosmic ray interactions in the Earth's atmosphere and are likely to have come from distant sources such as supermassive black holes in the centres of galaxies and gamma-ray bursts. I will discuss the experimental results which herald the birth of a new astronomy, as well as opening a new window on to physics beyond the Standard Model.