# The Lancaster, Manchester, Sheffield Consortium for Fundamental Physics: Particle Physics, From the Universe to the LHC

Lead Research Organisation: University of Manchester
Department Name: Physics and Astronomy

### Abstract

Particle physics is all about understanding the elementary building blocks of nature and their interactions. Over the years, physicists have developed the Standard Model of particle physics, which is extremely successful in describing a very wide range of natural phenomena from things as basic as how light works and why atoms form through to the complicated workings inside stars and the synthesis of nuclei in the first few minutes after the Big Bang. However, we know that the Standard Model is not the whole story for it leaves many questions unanswered. Our proposal focuses on these unanswered questions and the way that scientists hope to address them in the coming years using experiments like the Large Hadron Collider (LHC) or observations like those that will be made using the Planck satellite.

The discovery at the LHC of a Higgs boson is a major milestone in our quest to understand the origin of mass. It is certainly not, however, the whole story. The LHC experiments are working hard to measure the properties of the particle they have discovered. They are also searching for new particles such as those predicted by supersymmetry. If supersymmetry is discovered then it offers the hope to explain the origin of the Dark Matter that makes up a large fraction of the material that is known to exist in the Universe. The scientists in our consortium will explore the theory of supersymmetry and dark matter. We will use data from experiments like the LHC to identify which of the many possible variants of supersymmetry are allowed by the data and to suggest new ways to explore those models in experiments. Any "new physics" produced at the LHC will be produced as a result of smashing two protons into each other, a very complicated environment, usually in association with "jets" of other particles. Members of our consortium will explore how we can make use of these jets to learn more about the associated new physics: the better we understand the environment in which new physics occurs, the more we are able to learn about the new physics itself. This is a complicated business that often necessitates computer simulations of particle collisions. Our members are experts in these simulations and have plans on how the make them more accurate, which is necessary if we are to make the most of the exciting data from the LHC.

The Standard Model of particle physics is also insufficient when it comes to explaining the early history of the Universe, when it was hot and dense. The evidence is now very strong that the history began with an era of accelerating expansion, called inflation. We are experts on inflation and its consequences. Inflation makes the Universe featureless, except for tiny quantum fluctuations that cause the density of matter and energy in the Universe to vary with position. These initially small variations grow to become observable effects. One effect is the formation of the billions of galaxies that populate the night sky. Another is to leave a tiny imprint on the cosmic microwave background radiation (CMB), a faint hum of microwave radiation in which the Universe is bathed. The CMB is being studied in exquisite detail by the Planck satellite, which was launched in 2009. We are at the forefront of interpreting the Planck data in the hope of pinning down which of the various theories of the early universe are ruled out and which remain viable. The deficiencies of the Standard Model extend still further for it does not explain the amount nor even the existence of ordinary matter. Our scientists will use this to constrain possible physics beyond the Standard Model and to do that they need to master the dynamics of the Universe shortly after the end of inflation. Last but not least, we hope to understand better the mysterious "Dark Energy" that drives the current and future acceleration of the Universe: one possibility is that it is because Einstein's theory of gravity is not quite right and that is something we will explore.

### Planned Impact

See the attached "Pathways to Impact" document for details.
This project has impact beyond the international scientific community mainly through the training of highly skilled graduate students and postdoctoral researchers and through extensive "outreach" activities of various kinds aimed at engaging directly with the general public, school children, teachers, policy makers and the media. Undergraduate teaching is also impacted beneficially by our research.

### Publications

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Kahlhoefer F (2015) WIMP dark matter and unitarity-conserving inflation via a gauge singlet scalar in Journal of Cosmology and Astroparticle Physics

Karamitsos S (2018) Frame covariant nonminimal multifield inflation in Nuclear Physics B

Kimura T (2016) Nonlocal N = 1 $$\mathcal{N}=1$$ supersymmetry in Journal of High Energy Physics

Kowalska K (2014) Low fine tuning in the MSSM with higgsino dark matter and unification constraints in Journal of High Energy Physics

Kowalska K (2015) GUT-inspired SUSY and the muon g - 2 anomaly: prospects for LHC 14 TeV in Journal of High Energy Physics

Lyth D (2014) BICEP2, the curvature perturbation and supersymmetry in Journal of Cosmology and Astroparticle Physics

Lyth D (2015) Generating at l ? 60 in Journal of Cosmology and Astroparticle Physics

Mazumdar A (2014) Quantifying the reheating temperature of the universe in Nuclear Physics B

Mazumdar A (2016) Constraints on variations in inflaton decay rate from modulated preheating in Journal of Cosmology and Astroparticle Physics

Mazumdar A (2016) Nonthermal axion dark radiation and constraints in Physical Review D

Mazumdar A (2016) Possible resolution of the domain wall problem in the NMSSM in Physical Review D

McDonald J (2014) Sub-Planckian two-field inflation consistent with the Lyth bound in Journal of Cosmology and Astroparticle Physics

McDonald J (2015) Signatures of Planck corrections in a spiralling axion inflation model in Journal of Cosmology and Astroparticle Physics

McDonald J (2015) A minimal sub-Planckian axion inflation model with large tensor-to-scalar ratio in Journal of Cosmology and Astroparticle Physics

McDonald J (2014) Negative running of the spectral index, hemispherical asymmetry and the consistency of Planck with large in Journal of Cosmology and Astroparticle Physics

Mifsud J (2017) Probing the imprints of generalized interacting dark energy on the growth of perturbations in Journal of Cosmology and Astroparticle Physics

Pilaftsis A (2015) Symmetry Improved 2PI Effective Action and the Infrared Divergences of the Standard Model in Journal of Physics: Conference Series

Ponglertsakul S (2016) Stability of gravitating charged-scalar solitons in a cavity in Physical Review D

Roszkowski L (2014) Neutralino and gravitino dark matter with low reheating temperature in Journal of High Energy Physics

Roszkowski L (2015) Axino dark matter with low reheating temperature in Journal of High Energy Physics

Roszkowski L (2015) Prospects for dark matter searches in the pMSSM in Journal of High Energy Physics

Roszkowski L (2017) Towards understanding thermal history of the Universe through direct and indirect detection of dark matter in Journal of Cosmology and Astroparticle Physics

Salvio A (2016) Higgs stability and the 750 GeV diphoton excess in Physics Letters B

Sanchez J (2014) Inflationary buildup of a vector field condensate and its cosmological consequences in Journal of Cosmology and Astroparticle Physics

Description Progress on many fronts towards a better understanding of the universe, by developing theoretical models constrained by data from the LHC and cosmology experiments such as Planck.
Exploitation Route By continued research.
Sectors Education

Description Researchers supported by this award have been very active in outreach activities for the general public, schools and scientists from other fields.
First Year Of Impact 2014
Sector Education
Impact Types Cultural,Societal