Publications (118)319.07 Total impact

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ABSTRACT: We report on the results of our recent research published in [1] that shows that AdS/QCD generates predictions for the rate of diffractive \rhomeson electroproduction that are in agreement with data collected at the HERA electronproton collider [2,3]. Preliminary results of this research were presented in [4].11/2012; DOI:10.1063/1.4802123 
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ABSTRACT: We investigate the breakdown of collinear factorization for noninclusive observables in hadronhadron collisions. For pure QCD processes, factorization is violated at the threeloop level and it has a structure identical to that encountered previously in the case of superleading logarithms. In particular, it is driven by the noncommutation of Coulomb/Glauber gluon exchanges with other soft exchanges. Beyond QCD, factorization may be violated at the twoloop level provided that the hard subprocess contains matrix element contributions with phase differences between different colour topologies.Journal of High Energy Physics 06/2012; 2012(11). DOI:10.1007/JHEP11(2012)066 · 6.22 Impact Factor 
Article: AdS/QCD Holographic Wave Function for the rho Meson and Diffractive rho Meson Electroproduction
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ABSTRACT: We show that AdS/QCD generates predictions for the rate of diffractive rho meson electroproduction that are in agreement with data collected at the HERA electronproton collider.Physical Review Letters 03/2012; 109(8). DOI:10.1103/PhysRevLett.109.081601 · 7.73 Impact Factor 
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ABSTRACT: We report on a successful extraction of the twist2 and twist3 Distribution Amplitudes (DAs) of the rho meson using the HERA data on diffractive rho photoproduction. We extract these DAs using several Colour Glass Condensate (CGC) inspired and a Regge inspired dipole models. All our extracted DAs are consistent with Sum Rules and lattice predictions. 
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ABSTRACT: We explore how the colour of any new TeVscale resonances that decay into top quark pairs can be identified by studying the dependence of the observed crosssection on a central jet veto. To facilitate this study, colour octet resonance production was implemented in Pythia8 and colour singlet resonance production is simulated after minor modifications. We find that the colour of a 2 TeV resonance can be identified with 10/fb of data at a centreofmass energy of 14 TeV for a wide range of couplings, but only if the uncertainty in the theoretical prediction is dramatically reduced from its current level.Journal of High Energy Physics 08/2011; DOI:10.1007/JHEP01(2012)018 · 6.22 Impact Factor 
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ABSTRACT: This report is based on a tenweek program on "Gluons and the quark sea at highenergies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an ElectronIon Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for indepth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) threedimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC. 
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ABSTRACT: This report is based on a tenweek program on "Gluons and the quark sea at highenergies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an ElectronIon Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for indepth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) threedimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC. 
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ABSTRACT: We study dijet production in protonproton collisions with a veto on the emission of a third jet in the rapidity region in between the two leading ones. We resum the leading logarithms in the ratio of the transverse momentum of the leading jets and the veto scale and we match this result to leadingorder QCD matrix elements. We find that, in order to obtain sensible results, we have to modify the resummation and take into account energymomentum conservation effects. We compare our theoretical predictions for the gap fraction to experimental data measured by the ATLAS collaboration and find good agreement, although our results are affected by large theoretical uncertainties. We then discuss differences and similarities of our calculation to other theoretical approaches.Journal of High Energy Physics 07/2011; DOI:10.1007/JHEP08(2011)157 · 6.22 Impact Factor 
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ABSTRACT: We extract the leading twist2 and subleading twist3 Distribution Amplitudes (DAs) of the rho meson using the HERA data on diffractive rho photoproduction. We do so using several Colour Glass Condensate (CGC) inspired and a Regge inspired dipole models. We find that our extracted twist2 DA is not much model dependent and is consistent with QCD Sum Rules and lattice predictions. The extracted twist3 DA is more model dependent but is still consistent with the Sum Rules prediction.Journal of High Energy Physics 04/2011; 10(10). DOI:10.1007/JHEP10(2011)093 · 6.22 Impact Factor 
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ABSTRACT: Diffractive rho meson production has been identified as one of the important processes where saturation can be probed at a future ElectronIon Collider (EIC). A source of uncertainty in making predictions for this process lies within the assumed form of the meson lightcone wavefunction. We report here the results of reference [1] where a Reggeinspired dipole model was used to extract this wavefunction as well as the corresponding leading twist2 Distribution Amplitude from the current accurate HERA data. In addition, we shall check the robustness of the conclusions in reference [1] by using alternative Colour Glass Condensate dipole models. Comment: 9 pages, 5 figures. Proceedings Contribution for the workshop "Gluons and the quark sea at high energies: distributions, polarization, tomography", Institute for Nuclear Theory, Seattle, U.S. September 13 to November 19, 2010 
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ABSTRACT: We extract the lightcone wavefunctions of the ρ meson using the HERA data on diffractive ρ photoproduction. We find good agreement with predictions for the distribution amplitude based on QCD sum rules and from the lattice. We also find that the data prefer a transverse wavefunction with enhanced endpoint contributions.Journal of High Energy Physics 11/2010; 2010(11):113. DOI:10.1007/JHEP11(2010)037 · 6.22 Impact Factor 
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ABSTRACT: We investigate the theoretical description of the central exclusive production process, $h_1 + h_2 \to h_1+X+h_2$. Taking Higgs production as an example, we compute the subset of nexttoleading order corrections sensitive to the Sudakov factor appearing in the process. Our results agree with those originally presented by Khoze, Martin and Ryskin except that the scale appearing in the Sudakov factor, $\mu=0.62 \sqrt{\hat{s}}$, should be replaced with $\mu=\sqrt{\hat{s}}$, where $\sqrt{\hat{s}}$ is the invariant mass of the centrally produced system. We show that the replacement leads to approximately a factor 2 suppression in the crosssection for central system masses in the range 100500GeV. Comment: 5 pages, 2 figures; to appear in the proceedings of DIS2010 
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ABSTRACT: We review the subject of central exclusive particle production at high energy hadron colliders. In particular we consider reactions of the type A + B > A + X + B, where X is a fully specified system of particles that is well separated in rapidity from the outgoing beam particles. We focus on the case where the colliding particles are strongly interacting and mainly they will be protons (or antiprotons) as at the ISR, SppS, Tevatron and LHC. The data are surveyed and placed within the context of theoretical developments. Comment: 64 pagesProgress in Particle and Nuclear Physics 06/2010; DOI:10.1016/j.ppnp.2010.06.001 · 2.38 Impact Factor 
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ABSTRACT: Proceedings of the 13th International Conference on Elastic and Diffractive Scattering (Blois Workshop)  Moving Forward into the LHC Era 
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ABSTRACT: Proceedings from a 3day discussion on Standard Model discoveries with the first LHC data Comment: 9 contributions to the proceedings of the LHC Standard Model workshop 
Article: Central Exclusive Production in QCD
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ABSTRACT: We investigate the theoretical description of the central exclusive production process, h1+h2 > h1+X+h2. Taking Higgs production as an example, we sum logarithmically enhanced corrections appearing in the perturbation series to all orders in the strong coupling. Our results agree with those originally presented by Khoze, Martin and Ryskin except that the scale appearing in the Sudakov factor, mu=0.62 \sqrt{\hat{s}}, should be replaced with mu=\sqrt{\hat{s}}, where \sqrt{\hat{s}} is the invariant mass of the centrally produced system. We confirm this result using a fixedorder calculation and show that the replacement leads to approximately a factor 2 suppression in the crosssection for central system masses in the range 100500 GeV. Comment: 41 pages, 19 figures; minor typos fixed; version published in JHEPJournal of High Energy Physics 12/2009; 2010(1). DOI:10.1007/JHEP01(2010)121 · 6.22 Impact Factor 
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ABSTRACT: We study the effect of soft gluon resummation on the gapsbetweenjets crosssection at the LHC. We review the theoretical framework that enables one to sum logarithms of the hard scale over the veto scale to all orders in perturbation theory. We then present a study of the phenomenological impact of Coulomb gluon contributions and superleading logarithms on the gaps between jets crosssection at the LHC. Comment: Talk given at ''London workshop on Standard Model Discoveries with early LHC data'', UCL, London, 31 March1 April 2009. Also given at ''DIS 2009'', Madrid, Spain, 2630 Apr 2009 
Article: Jet vetoing at the LHC
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ABSTRACT: We study the effect of a veto on additional jets in the rapidity region between a pair of high transverse momentum jets at the LHC. We aim to sum the most important logarithms in the ratio of the jet transverse momentum to the veto scale and to that end we attempt to assess the significance of the superleading logarithms that appear at high orders in the perturbative expansion. We also compare our results to those of HERWIG++, in an attempt to ascertain the accuracy of the angular ordered parton shower. We find that there are large corrections that arise for large enough jet transverse momenta as a consequence of Coulomb gluon exchanges. Comment: 25 pagesJournal of High Energy Physics 05/2009; DOI:10.1088/11266708/2009/07/023 · 6.22 Impact Factor 
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ABSTRACT: We compute the rate for diffractive upsilon meson production at the Tevatron and the LHC. The upsilon is produced diffractively via the subprocess gamma + p > upsilon + p where the initial photon is radiated off an incoming proton (or antiproton). We consider the possibility to use low angle proton detectors to make a measurement of the gamma p crosssection and conclude that a measurement of the crosssection at a centre of mass energy in excess of 1 TeV is possible at the LHC. This is in the region where saturation effects are likely to reveal themselves. Comment: 14 pagesJournal of High Energy Physics 05/2009; DOI:10.1088/11266708/2009/06/034 · 5.62 Impact Factor 
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ABSTRACT: After a brief introduction to the physics of soft gluons in QCD we present a surprising prediction. Dijet production in hadronhadron collisions provides the paradigm, i.e. h_1 +h_2 \to jj+X. In particular, we look at the case where there is a restriction placed on the emission of any further jets in the region in between the primary (highest p_T) dijets. Logarithms in the ratio of the jet scale to the veto scale can be summed to all orders in the strong coupling. Surprisingly, factorization of collinear emissions fails at scales above the veto scale and triggers the appearance of double logarithms in the hard subprocess. The effect appears first at fourth order relative to the leading order prediction and is subleading in the number of colours.Nuclear Physics B  Proceedings Supplements 02/2009; DOI:10.1016/j.nuclphysbps.2009.03.133 · 0.88 Impact Factor
Publication Stats
2k  Citations  
319.07  Total Impact Points  
Top Journals
Institutions

1991–2012

The University of Manchester
 • School of Physics and Astronomy
 • Theoretical Physics Division
Manchester, England, United Kingdom


1999–2000

CERN
 Physics Department (PH)
Genève, Geneva, Switzerland


1996

Lund University
 Department of Theoretical Physics
Lund, Skåne, Sweden


1993

Oxon Epidemiology
Londinium, England, United Kingdom
