Contents

1. Introduction

The discovery of the Higgs boson at the LHC last year [1] [2] marked the completion of the Standard Model of particle physics. Arguably it has been one of the most successful theories in the history of scientific endeavour, however we already know it is insufficient.

The discovery of neutrino oscillations has proved that the neutrinos are not all massless, as they are assumed to be by the Standard Model. Though many theoretical approaches have been suggested on how this can be accommodated, experimental guidance is urgently required.

Likewise, the Standard Model is unable to provide an explanation of the baryonic matter – anti-matter asymmetry of the Universe. It was noted by Sakharov [3] that a solution to this problem would require some form of CP-violation in the early Universe. Though evidence of CP-violation has been found in the quark sector, additional physics beyond the Standard Model is required to account for the observed size of the asymmetry [4].

Once again the discovery of neutrino oscillations could hold the answer since the phenomenon also allows for the possibility of leptonic CP-violation. Various mechanisms have been proposed that would allow CP-violation in the lepton sector to provide the necessary asymmetry in the baryons [5]. Establishing whether or not CP-violation does occur in neutrinos is therefore a priority.

It is clear that the study of neutrinos is of vital importance to the future development of particle physics, in particular through the study of oscillations. However, as will be discussed in Chapter 2, precision measurements of neutrino oscillations are predicated on improving our understanding of neutrino-nucleus interactions.

There are multiple channels through which neutrinos can interact with nuclei and, as described in Chapter 3, many of them are in need of improvements in both our experimental and theoretical understanding. In Chapter 4 one interaction channel, coherent pion production, is identified as being of particular importance to the field, in need of experimental input, and with the potential for significant improvements in the near future. The T2K neutrino oscillation experiment, described in Chapter 5, provided an opportunity to contribute to this field, the results of which are reported in Chapter 6.

2. Neutrinos & Neutrino Oscillations

3. Neutrino Interactions

4. Coherent Pion Production

5. The T2K Experiment

6. A Search for Coherent Pion Production at T2K

7. Conclusions

References

  1. The ATLAS Collaboration
    Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
    Physics Letters B, Volume 716, p1-29, 2012
  2. The CMS Collaboration
    Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
    Physics Letters B, Volume 716, p30-61, 2012
  3. A.D. Sakharov
    Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe
    Soviet Physics Uspekhi, Volume 34, p392, 1991
  4. The Particle Data Group
    Review of Particle Physics - CP Violation in Meson Decays
    Physical Review D, Volume 86, p166-176, 2012
  5. A. Riotto
    Baryogenesis and Leptogenesis
    Journal of Physics: Conference Series, Volume 335, p012008, 2011