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Higgs cosmology

Scientific meeting

Location

Kavli Royal Society Centre, Chicheley Hall, Newport Pagnell, Buckinghamshire, MK16 9JJ

Overview

Theo Murphy scientific meeting organised by Professor Arttu Rajantie, Professor Malcolm Fairbairn, Dr Tommi Markkanen and Dr Astrid Eichhorn

A Higgs candidate event from the CMS experiment (image credit: CERN; CMS; T. McCauley and L. Taylor) superimposed on a Hubble Space Telescope image of the Abell 520 cluster (image credit: NASA; ESA; CFHT; CXO; M.J. Jee, University of California, Davis, and A. Mahdavi, San Francisco State University)

What can the discovery of the Higgs boson tell us about the early universe? This meeting will explore its implications for the theory of cosmological inflation, matter-antimatter asymmetry, dark matter and other open questions in cosmology.

A programme and biographies of the speakers and organisers are listed below. Speaker abstracts are also available below. Meeting papers will be published in a future version of Philosophical Transactions A.

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Recorded audio of the talks will be available on this page within 1 month of the end of this event.

Enquiries: Contact the Scientific Programmes team

Event organisers

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Schedule of talks

27 March

09:00-12:40

Session 1

4 talks Show detail Hide detail

Chairs

Dr Daniel G. Figueroa, CERN, Switzerland

09:10-09:40 Cosmological implications of Higgs near-criticality

Professor José R Espinosa, ICREA/IFAE Barcelona Spain

Abstract

The Standard Model electroweak vacuum lies very close to the boundary between stability and metastability, with the last option being the most likely. Espinosa will discuss several cosmological implications of this so-called ‘near-criticality’. In the metastable vacuum case, Espinosa will describe the main challenges that the survival of the electroweak vacuum faces during the evolution of the Universe. In the stable vacuum case, Espinosa will critically examine the possibility of implementing Higgs inflation.

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09:55-10:25 LHC: the energy and precision frontiers

Dr Sinead Farrington, University of Warwick, UK

Abstract

This talk will review the latest results from the LHC. Results will cover two main areas. At the energy frontier, the LHC can search for increasingly high mass Beyond Standard Model particles, some of which are dark matter candidates. At the precision frontier, the LHC is gathering ever-larger samples of Standard Model particles. This enables sensitive searches for deviations from Standard Model predictions in order to search for clues to Beyond Standard Model physics.

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11:10-11:40 Towards fundamental physics from the cosmic microwave background

Professor Hiranya Peiris, University College London, UK

Abstract

Surveys of the cosmic microwave background (CMB) carry immense promise for measurements of new physics beyond the Standard Models of cosmology and particle physics. Here, Peiris will present an overview of current cosmological constraints from the CMB, and survey the capabilities of upcoming experiments, taking account of Galactic foregrounds and the effect of lensing by intervening large-scale structure. Peiris will present some recent results that highlight the science enabled by combining CMB data with large galaxy surveys. Peiris will comment on some of the experimental and methodological innovations that are needed to realise the promise of upcoming surveys.

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11:55-12:25 Fate of the spectator Higgs during and after inflation

Professor Kari Enqvist, University of Helsinki, Finland

Abstract

Enqvist discusses the fluctuations of the Higgs field during inflation, the displacement of the mean Higgs field away from the origin, and its subsequent decay. Enqvist will also discuss the Higgs field fluctuations during the preheating period, pointing out that resonant behaviour can induce large fluctuations which may destabilize the electroweak vacuum. Such considerations provide an upper bound on quartic and trilinear interactions between the Higgs and the inflation.

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12:40-13:40

Lunch

13:40-14:10

Session 2

4 talks Show detail Hide detail

Chairs

Dr Fedor Bezrukov, The University of Manchester, UK

13:40-14:10 Higgs inflation and its observational signatures

Professor Juan Garcia-Bellido, Universidad Autonoma de Madrid, Spain

Abstract

The possibility that the hypothetical inflaton field be the Higgs of the Standard Model is an extremely economical scenario. Garcia-Bellido will discuss the present cosmological constraints that can be placed on the parameters of the model, and the future observational signatures that may arise from such a scenario.

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14:25-14:55 Higgs and the universe: searching for simplicity

Professor Mikhail Shaposhnikov, École polytechnique fédérale de Lausanne, Switzerland

Abstract

After the Higgs boson has been discovered, the Standard Model of particle physics became a confirmed theory, potentially valid up to the Planck scale and allowing one to trace the evolution of the universe from the inflationary stage till the present days. Shaposhnikov will overview the Higgs inflation and its relation to the possible metastability of the electroweak vacuum, as well as the Higgs field importance for baryogenesis and dark matter production.

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15:25-16:00 Poster session

16:00-16:30 The Higgs as a link from particle physics to cosmology

Dr Veronica Sanz, University of Sussex, UK

Abstract

In this talk Sanz will review some of the ideas which link the Higgs particle and the mechanism of electroweak symmetry breaking with other events in the Universe's history, including inflation and reheating. The connection among different sources of data (colliders, underground experiments, cosmological probes) will be emphasized

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28 March

09:00-12:30

Session 3

4 talks Show detail Hide detail

Chairs

Dr Marieke Postma, Nikhef, Netherlands

09:00-09:30 Vacuum stability in the Early Universe and the backreaction of classical gravity

Dr Tommi Markkanen, King's College London, UK

Abstract

In the case of a metastable electroweak vacuum the quantum corrected effective potential plays a crucial role in the potential instability of the Standard Model. In the Early Universe, in particular during inflation and reheating, this instability can be triggered leading to catastrophic vacuum decay. In this talk Markkanen discusses in detail how the large spacetime curvature of the Early Universe can be incorporated in the calculation and in many cases significantly modify the flat space prediction. The two key new elements are the unavoidable generation of the non-minimal coupling between the Higgs field and the scalar curvature of gravity and a curvature induced contribution to the running of the constants. For the minimal set up of the Standard Model and a decoupled inflation sector Markkanen shows how a metastable vacuum can lead to very tight bounds for the non-minimal coupling.

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09:45-10:15 RG flow of the Higgs potential

Professor Holger Gies, Friedrich-Schiller-Universität Jena, Germany

Abstract

Data from LHC experiments suggest that the standard model is in a near-critical regime, offering the possibility that the physical electroweak vacuum state is unstable. Gies’ group critically re-examine conventional perturbative arguments and show that the stability bound on the Higgs mass depend on the largely unknown details of the short distance physics within the standard model. The group determine new standard model stability bounds from nonperturbative RG flows as a functional of the short-distance action, relaxing conventional stability bounds. Gies shows that a metastability of the Higgs potential also has to be encoded in the short distance properties of the standard model. Studying the nonperturbative RG flow of metastable potentials gives us access to the quantum phase diagram of the model as well as to the interplay of false vacuum decay and convexity of the effective potential.

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11:00-11:30 Is electroweak baryogenesis dead?

Professor James Cline, McGill University, Canada

Abstract

Electroweak baryogenesis is an extremely testable framework. Its most popular realizations, in the MSSM and in general two Higgs doublet models, are either excluded or pushed to such a small corner of parameter space as to strain credibility. One might wonder whether it is still possible to design robust working models in light of new LHC constraints. Professor Cline will address this question, with emphasis on a model that can also provide the dark matter.

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11:45-12:15 Higgs condensate relaxation and the origin of matter

Professor Alexander Kusenko, University of California Los Angeles, USA & Kavli IPMU, University of Tokyo, Japan

Abstract

The recent measurement of the Higgs boson mass implies a relatively slow rise of the Standard Model Higgs potential at large scales. This allows the Higgs field to develop a large vacuum expectation value during inflation. The relaxation of the Higgs field from its large postinflationary value to the minimum of the effective potential represents an interesting new stage in the evolution of the universe. The matter-antimatter asymmetry could be generated during this epoch.

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12:30-13:30

Lunch

13:30-17:00

Session 4

4 talks Show detail Hide detail

Chairs

Dr Enrico Morgante, DESY, Germany

13:30-14:00 Higgs-portal dark matter: status and prospects

Professor Abdelhak Djouadi, Université Paris-Sud, France

Abstract

Djouadi discusses scenarios in which the particles that form the dark matter in the universe interact mainly or exclusively with Higgs bosons, either the one of the standard model of particle physics or those of its extensions. The case of scalar, fermionic and vector dark matter particles are considered. Present constraints from collider experiments like the LHC and astroparticle physics experiments that search directly or indirectly for these particles are summarised. The prospects for future studies are discussed.

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14:15-16:45 The serendipity of electroweak baryogenesis

Professor Geraldine Servant, DESY and the University of Hamburg, Germany

Abstract

Servant will report how the CKM matrix can be the source of CP-violation for electroweak baryogenesis if Yukawa couplings vary at the same time as the Higgs is acquiring its vacuum expectation value, offering new avenues for electroweak baryogenesis. The advantage of this approach is that it circumvents the usual bounds from electric dipole moments. These ideas apply if the mechanism explaining the flavour structure of the Standard Model is connected to electroweak symmetry breaking, as motivated for instance in Randall–Sundrum or composite Higgs models. Servant will show how this can be compatible with experimental constraints and naturally leads to the correct amount of the baryon asymmetry.

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15:30-16:00 Gravitational waves from a first order electroweak phase transition

Dr David Weir, University of Helsinki, Finland

Abstract

The direct detection of gravitational waves by LIGO has led to heightened interest in other observable sources of gravitational waves, both astrophysical and primordial. There is also growing interest in proposed detectors such as LISA, scheduled for launch in 2034. In this talk, David will focus on one possible primordial source of gravitational waves: first order phase transitions in the early universe. The resulting gravitational wave signal is a good candidate for detection at next-generation gravitational wave detectors. An electroweak-scale first order phase transition could yield information about physics beyond the Standard Model that will otherwise remain out of reach of colliders for quite some time. David will discuss efforts to simulate and model the phase transition and the resulting production of gravitational waves.

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16:15-17:00 Summary of discussions

Higgs cosmology Kavli Royal Society Centre, Chicheley Hall Newport Pagnell Buckinghamshire MK16 9JJ