Publications by Lucian Harland-Lang

Searching for the odderon in ultraperipheral proton-ion collisions at the LHC

PHYSICAL REVIEW D 99 (2019) ARTN 034011

LA Harland-Lang, VA Khoze, AD Martin, MG Ryskin

On the consistent use of scale variations in PDF fits and predictions


LA Harland-Lang, RS Thorne

A fresh look at ALP searches in fixed target experiments

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 793 (2019) 281-289

L Harland–Lang, J Jaeckel, M Spannowsky

© 2019 A significant number of high power proton beams are available or will go online in the near future. This provides exciting opportunities for new fixed target experiments and the search for new physics in particular. In this note we will survey these beams and consider their potential to discover new physics in the form of axion-like particles, identifying promising locations and set ups. To achieve this, we present a significantly improved calculation of the production of axion-like particles in the coherent scattering of protons on nuclei, valid for lower ALP masses and/or beam energies. We also provide a new publicly available tool for this process: the Alpaca Monte Carlo generator. This will impact ongoing and planned searches based on this process.

LHC searches for Dark Matter in compressed mass scenarios: challenges in the forward proton mode


LA Harland-Lang, VA Khoze, MG Ryskin, M Tasevsky

Exclusive LHC physics with heavy ions: SuperChic 3.

The European physical journal. C, Particles and fields 79 (2019) 39-39

LA Harland-Lang, VA Khoze, MG Ryskin

We present results of the updated SuperChic 3 Monte Carlo event generator for central exclusive production. This extends the previous treatment of proton-proton collisions to include heavy ion (pA and AA) beams, for both photon and QCD-initiated production, the first time such a unified treatment of exclusive processes has been presented in a single generator. To achieve this we have developed a theory of the gap survival factor in heavy ion collisions, which allows us to derive some straightforward results about the A scaling of the corresponding cross sections. We compare against the recent ATLAS and CMS measurements of light-by-light scattering at the LHC, in lead-lead collisions. We find that the background from QCD-initiated production is expected to be very small, in contrast to some earlier estimates. We also present results from new photon-initiated processes that can now be generated, namely the production of axion-like particles, monopole pairs and monopolium, top quark pair production, and the inclusion of W loops in light-by-light scattering.

Towards ultimate parton distributions at the high-luminosity LHC

European Physical Journal C 78 (2018)

RA Khalek, S Bailey, J Gao, L Harland-Lang, J Rojo

© 2018, The Author(s). Since its start of data taking, the LHC has provided an impressive wealth of information on the quark and gluon structure of the proton. Indeed, modern global analyses of parton distribution functions (PDFs) include a wide range of LHC measurements of processes such as the production of jets, electroweak gauge bosons, and top quark pairs. In this work, we assess the ultimate constraining power of LHC data on the PDFs that can be expected from the complete dataset, in particular after the High-Luminosity (HL) phase, starting in around 2025. The huge statistics of the HL-LHC, delivering L=3ab-1 to ATLAS and CMS and L=0.3ab-1 to LHCb, will lead to an extension of the kinematic coverage of PDF-sensitive measurements as well as to an improvement in their statistical and systematic uncertainties. Here we generate HL-LHC pseudo-data for different projections of the experimental uncertainties, and then quantify the resulting constraints on the PDF4LHC15 set by means of the Hessian profiling method. We find that HL-LHC measurements can reduce PDF uncertainties by up to a factor of 2 to 4 in comparison to state-of-the-art fits, leading to few-percent uncertainties for important observables such as the Higgs boson transverse momentum distribution via gluon-fusion. Our results illustrate the significant improvement in the precision of PDF fits achievable from hadron collider data alone, and motivate the continuation of the ongoing successful program of PDF-sensitive measurements by the LHC collaborations.

The structure of the proton in the LHC precision era


J Gao, L Harland-Lang, J Rojo

The impact of LHC jet data on the MMHT PDF fit at NNLO.

The European physical journal. C, Particles and fields 78 (2018) 248-

LA Harland-Lang, AD Martin, RS Thorne

We investigate the impact of the high precision ATLAS and CMS 7 TeV measurements of inclusive jet production on the MMHT global PDF analysis at next-to-next-to-leading order (NNLO). This is made possible by the recent completion of the long-term project to calculate the NNLO corrections to the hard cross section. We find that a good description of the ATLAS data is not possible with the default treatment of experimental systematic errors, and propose a simplified solution that retains the dominant physical information of the data. We then investigate the fit quality and the impact on the gluon PDF central value and uncertainty when the ATLAS and CMS data are included in a MMHT fit. We consider both common choices for the factorization and renormalization scale, namely the inclusive jet transverse momentum, p⊥ , and the leading jet p⊥ , as well as the different jet radii for which the ATLAS and CMS data are made available. We find that the impact of these data on the gluon is relatively insensitive to these inputs, in particular the scale choice, while the inclusion of NNLO corrections tends to improve the data description somewhat and has a qualitatively similar though not identical impact on the gluon in comparison to NLO.

Parton distributions and lattice QCD calculations: A community white paper


H-W Lin, ER Nocera, F Olness, K Orginos, J Rojo, A Accardi, C Alexandrou, A Bacchetta, G Bozzi, J-W Chen, S Collins, A Cooper-Sarkar, M Constantinou, L Del Debbio, M Engelhardt, J Green, R Gupta, LA Harland-Lang, T Ishikawa, A Kusina, K-F Liu, S Liuti, C Monahan, P Nadolsky, J-W Qiu, I Schienbein, G Schierholz, RS Thorne, W Vogelsang, H Wittig, C-P Yuan, J Zanotti

chi(c) decays and the gluon component of the eta ', eta mesons

PHYSICS LETTERS B 770 (2017) 88-92

LA Harland-Lang, VA Khoze, MG Ryskin, AG Shuvaev

LHC forward physics


K Akiba, M Akbiyik, M Albrow, M Arneodo, V Avati, J Baechler, OV Baillie, P Bartalini, J Bartels, S Baur, C Baus, W Beaumont, U Behrens, D Berge, M Berretti, E Bossini, R Boussarie, S Brodsky, M Broz, M Bruschi, P Bussey, W Byczynski, JC Cabanillas Noris, E Calvo Villar, A Campbell, F Caporale, W Carvalho, G Chachamis, E Chapon, C Cheshkov, J Chwastowski, R Ciesielski, D Chinellato, A Cisek, V Coco, P Collins, JG Contreras, B Cox, D de Jesus Damiao, P Davis, M Deile, D D'Enterria, D Druzhkin, B Ducloue, R Dumps, R Dzhelyadin, P Dziurdzia, M Eliachevitch, P Fassnacht, F Ferro, S Fichet, D Figueiredo, B Field, D Finogeev, R Fiore, J Forshaw, A Gago Medina, M Gallinaro, A Granik, G von Gersdorff, S Giani, K Golec-Biernat, VP Goncalves, P Goettlicher, K Goulianos, J-Y Grosslord, LA Harland-Lang, H Van Haevermaet, M Hentschinski, R Engel, G Herrera Corral, J Hollar, L Huertas, D Johnson, I Katkov, O Kepka, M Khakzad, L Kheyn, V Khachatryan, VA Khoze, S Klein, M van Klundert, F Krauss, A Kurepin, N Kurepin, K Kutak, E Kuznetsova, G Latino, P Lebiedowicz, B Lenzi, E Lewandowska, S Liu, A Luszczak, M Luszczak, JD Madrigal, M Mangano, Z Marcone, C Marquet, AD Martin, T Martin, MI Martinez Hernandez, C Martins, C Mayer, R Mc Nulty, P Van Mechelen, R Macula, E Melo da Costa, T Mertzimekis, C Mesropian, M Mieskolainen, N Minafra, IL Monzon, L Mundim, B Murdaca, M Murray, H Niewiadowski, J Nystrand, EG de Oliveira, R Orava, S Ostapchenko, K Osterberg, A Panagiotou, A Papa, R Pasechnik, T Peitzmann, LA Perez Moreno, T Pierog, J Pinfold, M Poghosyan, ME Pol, W Prado, V Popov, M Rangel, A Reshetin, J-P Revol, M Rijssenbeek, M Rodriguez, B Roland, C Royon, M Ruspa, M Ryskin, A Sabio Vera, G Safronov, T Sako, H Schindler, D Salek, K Safarik, M Saimpert, A Santoro, R Schicker, J Seger, S Sen, A Shabanov, W Schafer, G Gil Da Silveira, P Skands, R Soluk, A van Spilbeeck, R Staszewski, S Stevenson, WJ Stirling, M Strikman, A Szczurek, L Szymanowski, JDT Takaki, M Tasevsky, K Taesoo, C Thomas, SR Torres, A Tricomi, M Trzebinski, D Tsybychev, N Turini, R Ulrich, E Usenko, J Varela, M Lo Vetere, A Villatoro Tello, A Vilela Pereira, D Volyanskyy, S Wallon, G Wilkinson, H Woehrmann, KC Zapp, Y Zoccarato

The production of a diphoton resonance via photon-photon fusion


LA Harland-Lang, VA Khoze, MG Ryskin

MMHT2014 PDFs - HERA I+II data and other updates

Proceedings of Science 11-15-April-2016 (2016)

RS Thorne, LA Harland-Lang, AD Martin

We will cover a number of topics: some clarifications on MMHT PDFs with varying quark masses; a review of the fit to final HERA data, with consequences for MMHT PDFs, and a study of the fit quality; a brief introduction to topics just starting investigation, mainly the inclusion of new LHC data sets.

Jet activity as a probe of high-mass resonance production


LA Harland-Lang, VA Khoze, MG Ryskin, M Spannowsky

Photon-initiated processes at high mass

PHYSICAL REVIEW D 94 (2016) ARTN 074008

LA Harland-Lang, VA Khoze, MG Ryskin

Sudakov effects in photon-initiated processes

PHYSICS LETTERS B 761 (2016) 20-24

LA Harland-Lang, VA Khoze, MG Ryskin

The photon PDF in events with rapidity gaps


LA Harland-Lang, VA Khoze, MG Ryskin

The impact of the final HERA combined data on PDFs obtained from a global fit.

The European physical journal. C, Particles and fields 76 (2016) 186-

LA Harland-Lang, AD Martin, P Motylinski, RS Thorne

We investigate the effect of including the HERA run I + II combined cross section data on the MMHT2014 PDFs. We present the fit quality within the context of the global fit and when only the HERA data are included. We examine the changes in both the central values and the uncertainties in the PDFs. We find that the prediction for the data is good, and only relatively small improvements in [Formula: see text] and changes in the PDFs are obtained with a refit at both NLO and NNLO. PDF uncertainties are slightly reduced. There is a small dependence of the fit quality on the value of [Formula: see text]. This can be improved by phenomenologically motived corrections to [Formula: see text] which parametrically are largely in the form of higher-twist type contributions.

Charm and beauty quark masses in the MMHT2014 global PDF analysis


LA Harland-Lang, AD Martin, P Motylinski, RS Thorne

Exclusive physics at the LHC with SuperChic 2


LA Harland-Lang, VA Khoze, MG Ryskin