Peter Hayman

Selected Publications

1. Frontiers

   Point-Particle Catalysis

   Peter Hayman, and Cliff P. Burgess

   Abs arXiv Bibtex

   We use the point-particle effective field theory (PPEFT) framework to describe particle-conversion mediated by a flavour-changing coupling to a point-particle. We do this for a toy model of two non-relativistic scalars coupled to the same point-particle, on which there is a flavour-violating coupling. It is found that the point-particle couplings all must be renormalized with respect to a radial cut-off near the origin, and it is an invariant of the flow of the flavour-changing coupling that is directly related to particle-changing cross-sections. At the same time, we find an interesting dependence of those cross-sections on the ratio k_out/k_in of the outgoing and incoming momenta, which can lead to a 1/k_in enhancement in certain regimes. We further connect this model to the case of a single-particle non-self-adjoint (absorptive) PPEFT, as well as to a PPEFT of a single particle coupled to a two-state nucleus. These results could be relevant for future calculations of any more complicated reactions, such as nucleus-induced electron-muon conversions, monopole catalysis of baryon number violation, as well as nuclear transfer reactions.

   @article{hayman_point-particle_2019,
     abbr = {Frontiers},
     arxiv = {1905.00103},
     title = {Point-Particle Catalysis},
     volume = {7},
     issn = {2296-424X},
     url = {https://www.frontiersin.org/articles/10.3389/fphy.2019.00167/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Physics&id=469321},
     doi = {10.3389/fphy.2019.00167},
     journaltitle = {Front. Phys.},
     author = {Hayman, Peter and Burgess, Cliff P.},
     urldate = {2019-11-06},
     date = {2019},
     keywords = {Effective Field Theories, Catalysis, Flavour violation, High energy physics - theory, Nuclear theory},
     file = {Full Text PDF:/home/peter/Nextcloud/Zotero/storage/93M9GIC3/Hayman and Burgess - 2019 - Point-Particle Catalysis.pdf:application/pdf},
     selected = true
   }

2. PRA

   Reduced theoretical error for ⁴He⁺ spectroscopy

   C. P. Burgess, P. Hayman, Markus Rummel, and László Zalavári

   Abs arXiv Bibtex

   We apply point-particle effective field theory to electronic and muonic 4He+ ions, and use it to identify linear combinations of spectroscopic measurements for which the theoretical uncertainties are much smaller than for any particular energy levels. The error is reduced because these combinations are independent of all short-range physics effects up to a given order in the expansion in the small parameters R/aB and Zα (where R and aB are the ion’s nuclear and Bohr radii). In particular, the theory error is not limited by the precision with which nuclear matrix elements can be computed, or compromised, by the existence of any novel short-range interactions, should these exist. These combinations of 4He measurements therefore provide particularly precise tests of quantum electrodynamics. The restriction to 4He arises because our analysis assumes a spherically symmetric nucleus, but the argument used is more general and extendable to both nuclei with spin, and to higher orders in R/aB and Zα.

   @article{burgess_reduced_2018,
     abbr = {{P}{R}{A}},
     arxiv = {1708.09768},
     title = {Reduced theoretical error for \textsuperscript{4}{He}\textsuperscript{+} spectroscopy},
     volume = {98},
     url = {https://link.aps.org/doi/10.1103/PhysRevA.98.052510},
     doi = {10.1103/PhysRevA.98.052510},
     pages = {052510},
     number = {5},
     publisher = aps,
     journaltitle = {Phys. Rev. A},
     author = {Burgess, C. P. and Hayman, P. and Rummel, Markus and Zalavári, László},
     urldate = {2019-03-28},
     date = {2018-11-19},
     selected = true
   }

3. JCAP

   Magnon inflation: slow roll with steep potentials

   Peter Adshead, Diego Blas, C. P. Burgess, Peter Hayman, and Subodh P. Patil

   Abs arXiv Bibtex

   We find multi-scalar effective field theories (EFTs) that can achieve a slow inflationary roll despite having a scalar potential that does not satisfy 𝒢ab ∂a V ∂b V ≪ V2/Mp2 (where 𝒢ab is the target-space metric). They evade the usual slow-roll conditions on V because their kinetic energies are dominated by single-derivative terms rather than the usual two-derivative terms. Single derivatives dominate during slow roll and so do not require a breakdown of the usual derivative expansion that underpins calculational control in much of cosmology. The presence of such terms requires some sort of UV Lorentz-symmetry breaking during inflation (besides the usual cosmological breaking). Chromo-natural inflation provides one particular example of a UV theory that can generate the multi-field single-derivative terms we consider, and we argue that the EFT we find indeed captures the slow-roll conditions for its background evolution. We also show that our EFT can be understood as a multi-field generalization of the single-field Cuscuton models. The multi-field case introduces a new feature, however: the scalar kinetic terms define a target-space 2-form, ℱab, whose antisymmetry gives new ways for slow roll to be achieved.

   @article{adshead_magnon_2016,
     abbr = {{J}{C}{A}{P}},
     arxiv = {1604.06048},
     title = {Magnon inflation: slow roll with steep potentials},
     volume = {2016},
     issn = {1475-7516},
     url = {https://doi.org/10.1088%2F1475-7516%2F2016%2F11%2F009},
     doi = {10.1088/1475-7516/2016/11/009},
     shorttitle = {Magnon inflation},
     pages = {009--009},
     number = {11},
     journaltitle = {J. Cosmol. Astropart. Phys.},
     author = {Adshead, Peter and Blas, Diego and Burgess, C. P. and Hayman, Peter and Patil, Subodh P.},
     urldate = {2019-03-28},
     date = {2016-11},
     langid = {english},
     file = {IOP Full Text PDF:/home/peter/Nextcloud/Zotero/storage/TPYRMJFZ/Adshead et al. - 2016 - Magnon inflation slow roll with steep potentials.pdf:application/pdf},
     selected = true
   }