Recent Publications

Charged Particle Production in High Q2 Deep-Inelastic Scattering at HERA

(H1 Collab., F.D. Aaron et al., Phys. Lett. B 654 (2007) 148.)

I was responsible for the analysis, editing and publication of the paper. The paper presents a fundamental study of charge particle production and tests quark fragmentation universality by comparing directly with similar results from e+e- annihilation, Mote Carlo models and NLO QCD predictions. While the results broadly support universality there are clear differences in the detail, especially when compared with the NLO predictions, that question are understanding of the fragmentation process.

Strangeness Production at low Q2 in Deep-Inelastic ep Scattering at HERA

(H1 Collab., Submitted to Eur. Phys. J. C, 10/08)

This paper follows on from previous internal H1 studies I made and is a natural extension of the charged particle production paper. It presents a wide survey of K0 and Λ production data. An important observation of this paper is that the strangeness suppression factor (the suppression of strange light hadron production compared to other light hadrons) as obtained from fits to e+e- annihilation data does not describe strangeness suppression in ep data, further questioning our understanding of fragmentation.

Inclusive Photoproduction of ρ0, K*0 and φ Mesons at HERA

(H1 Collab., F.D. Aaron et al., Submitted to Phys Lett B, 01/09)

This challenging analysis carried out by a PhD student, further extends the work of the last two papers into the photoproduction domain. Its unusual for a H1 publication as it compares directly with similar results from RHIC experiments. The strangeness suppression factor, measured from the φ/K*0 ratio, is found to be in agreement with that from the STAR experiment from proton collisions. However comparisons with Monte Carlo models shows a significant difference.

Munich Football stadium, 2007

The above three papers represent part of a longer term study into particle production and fragmentation which will continue into the future.

Photoproduction of Dijets with High Transverse Momenta at HERA

(H1 Collab., A. Aktas et al., Phys. Lett. B 639 (2006) 21.)

I wrote the paper and took through to final publication this important analysis after the student responsible for the analysis completed his PhD and left. The results are expected to be sensitive to the gluon distribution in the proton especially at high xbj where there are large uncertainties. It is important to constrain the high xbj structure of the proton in order to understand the highest energy collisions taking place at the LHC.

Inclusive and Multi-Jet Production at high Q2 and measurement of αs using full HERA data

(H1 Collab., F.D. Aaron et al. in litt.)

This analysis represents the first major summary paper using all H1 HERA data produced by the hadronic final state and QCD working group that I convene. It includes studies of inclusive, di- and tri-jet production for a variety of different observables. It presents one of the most experimentally accurate measurements of αs in world. It is able to show the clear running of αs in one experiment. The results are also able to place significant constraints on the structure of the gluon in the proton and will be included into future proton PDF fits.

While the proton structure function measurements from HERA provide the major constraint on the proton PDF, it is clear that the jet measurements presented above will provide important and unique data for a more accurate proton PDF fits.