Publications by Gavin Salam

alpha(s) from the top quark pair production cross section


S Bethke, G Dissertori, T Klijnsma, GP Salam

How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function.

Physical review letters 117 (2016) 242002-

A Manohar, P Nason, GP Salam, G Zanderighi

It has become apparent in recent years that it is important, notably for a range of physics studies at the Large Hadron Collider, to have accurate knowledge on the distribution of photons in the proton. We show how the photon parton distribution function (PDF) can be determined in a model-independent manner, using electron-proton (ep) scattering data, in effect viewing the ep→e+X process as an electron scattering off the photon field of the proton. To this end, we consider an imaginary, beyond the Standard Model process with a flavor changing photon-lepton vertex. We write its cross section in two ways: one in terms of proton structure functions, the other in terms of a photon distribution. Requiring their equivalence yields the photon distribution as an integral over proton structure functions. As a result of the good precision of ep data, we constrain the photon PDF at the level of 1%-2% over a wide range of momentum fractions.


40 (2016) UNSP 100001

C Patrignani, K Agashe, G Aielli, C Amsler, M Antonelli, DM Asner, H Baer, S Banerjee, RM Barnett, T Basaglia, CW Bauer, JJ Beatty, VI Belousov, J Beringer, S Bethke, H Bichsel, O Biebel, E Blucher, G Brooijmans, O Buchmueller, V Burkert, MA Bychkov, RN Cahn, M Carena, A Ceccucci, A Cerri, D Chakraborty, M-C Chen, RS Chivukula, K Copic, G Cowan, O Dahl, G D'Ambrosio, T Damour, D de Florian, A de Gouvea, T DeGrand, P de Jong, G Dissertori, BA Dobrescu, M D'Onofrio, M Doser, M Drees, HK Dreiner, DA Dwyer, P Eerola, S Eidelman, J Ellis, J Erler, VV Ezhela, W Fetscher, BD Fields, B Foster, A Freitas, H Gallagher, L Garren, H-J Gerber, G Gerbier, T Gershon, T Gherghetta, AA Godizov, M Goodman, C Grab, AV Gritsan, C Grojean, DE Groom, M Gruenewald, A Gurtu, T Gutsche, HE Haber, K Hagiwara, C Hanhart, S Hashimoto, Y Hayato, KG Hayes, A Hebecker, B Heltsley, JJ Hernandez-Rey, K Hikasa, J Hisano, A Hoecker, J Holder, A Holtkamp, J Huston, T Hyodo, K Irwin, JD Jackson, KF Johnson, M Kado, M Karliner, UF Katz, SR Klein, E Klempt, RV Kowalewski, F Krauss, M Kreps, B Krusche, YV Kuyanov, Y Kwon, O Lahav, J Laiho, P Langacker, A Liddle, Z Ligeti, C-J Lin, C Lippmann, TM Liss, L Littenberg, KS Lugovsky, SB Lugovsky, A Lusiani, Y Makida, F Maltoni, T Mannel, AV Manohar, WJ Marciano, AD Martin, A Masoni, J Matthews, U-G Meissner, D Milstead, RE Mitchell, P Molaro, K Monig, F Moortgat, MJ Mortonson, H Murayama, K Nakamura, M Narain, P Nason, S Navas, M Neubert, P Nevski, Y Nir, KA Olive, SP Griso, J Parsons, JA Peacock, M Pennington, ST Petcov, VA Petrov, A Piepke, A Pomarol, A Quadt, S Raby, J Rademacker, G Raffelt, BN Ratcliff, P Richardson, A Ringwald, S Roesler, S Rolli, A Romaniouk, LJ Rosenberg, JL Rosner, G Rybka, RA Ryutin, CT Sachrajda, Y Sakai, GP Salam, S Sarkar, F Sauli, O Schneider, K Scholberg, AJ Schwartz, D Scott, V Sharma, SR Sharpe, T Shutt, M Silari, T Sjostrand, P Skands, T Skwarnicki, JG Smith, GF Smoot, S Spanier, H Spieler, C Spiering, A Stahl, SL Stone, Y Sumino, T Sumiyoshi, MJ Syphers, F Takahashi, M Tanabashi, K Terashi, J Terning, RS Thorne, L Tiator, M Titov, NP Tkachenko, NA Tornqvist, D Tovey, G Valencia, R Van de Water, N Varelas, G Venanzoni, MG Vincter, P Vogel, A Vogt, SP Wakely, W Walkowiak, CW Walter, D Wands, DR Ward, MO Wascko, G Weiglein, DH Weinberg, EJ Weinberg, M White, LR Wiencke, S Wiliocq, CC Wohl, L Wolfenstein, J Womersley, CL Woody, RL Workman, W-M Yao, GP Zeller, OV Zenin, R-Y Zhu, F Zimmermann, PA Zyla, J Anderson, G Harper, VS Lugovsky, P Schaffner, PD Grp

Inclusive jet spectrum for small-radius jets

Journal of High Energy Physics Springer 2016 (2016) 57-

M Dasgupta, FA Dreyer, G Salam, G Soyez

Following on our earlier work on leading-logarithmic (LLR) resummations for the properties of jets with a small radius, R, we here examine the phenomenological considerations for the inclusive jet spectrum. We discuss how to match the NLO predictions with small-R resummation. As part of the study we propose a new, physically-inspired prescription for fixed-order predictions and their uncertainties. We investigate the R-dependent part of the next-to-next-to-leading order (NNLO) corrections, which is found to be substantial, and comment on the implications for scale choices in inclusive jet calculations. We also examine hadronisation corrections, identifying potential limitations of earlier analytical work with regards to their pt-dependence. Finally we assemble these different elements in order to compare matched (N)NLO+LLR predictions to data from ALICE and ATLAS, finding improved consistency for the R-dependence of the results relative to NLO predictions.

Jet-vetoed Higgs cross section in gluon fusion at N3LO+NNLL with small-R resummation

Journal of High Energy Physics Springer Verlag 2016 (2016) 1-31

A Banfi, F Caola, F Dreyer, PF Monni, G Salam, G Zanderighi, F Dulat

We present new results for the jet-veto efficiency and zero-jet cross section in Higgs production through gluon fusion. We incorporate the N3LO corrections to the total cross section, the NNLO corrections to the 1-jet rate, NNLL resummation for the jet p t and LL resummation for the jet radius dependence. Our results include known finite-mass corrections and are obtained using the jet-veto efficiency method, updated relative to earlier work to take into account what has been learnt from the new precision calculations that we include. For 13 TeV collisions and using our default choice for the renormalisation and factorisation scales, μ 0 = m H /2, the matched prediction for the jet-veto efficiency increases the pure N3LO prediction by about 2% and the two have comparable uncertainties. Relative to NNLO+NNLL results, the new prediction is 2% smaller and the uncertainty reduces from about 10% to a few percent. Results are also presented for the central scale μ 0 = m H .

World Summary of alpha(s) (2015)


S Bethke, G Dissertori, G Salam

The PDF4LHC report on PDFs and LHC data: results from Run I and preparation for Run II


J Rojo, A Accardi, RD Ball, A Cooper-Sarkar, A de Roeck, S Farry, J Ferrando, S Forte, J Gao, L Harland-Lang, J Huston, A Glazov, M Gouzevitch, C Gwenlan, K Lipka, M Lisovyi, M Mangano, P Nadolsky, L Perrozzi, R Placakyte, V Radescu, GP Salam, R Thorne

Towards an understanding of the correlations in jet substructure


D Adams, A Arce, L Asquith, M Backovic, T Barillari, P Berta, D Bertolini, A Buckley, J Butterworth, RCC Toro, J Caudron, Y-T Chien, J Cogan, B Cooper, D Curtin, C Debenedetti, J Dolen, M Eklund, S El Hedri, SD Ellis, T Embry, D Ferencek, J Ferrando, S Fleischmann, M Freytsis, M Giulini, Z Han, D Hare, P Harris, A Hinzmann, R Hoing, A Hornig, M Jankowiak, K Johns, G Kasieczka, R Kogler, W Lampl, AJ Larkoski, C Lee, R Leone, P Loch, DL Mateos, HK Lou, M Low, P Maksimovic, I Marchesini, S Marzani, L Masetti, R McCarthy, S Menke, DW Miller, K Mishra, B Nachman, P Nef, FT O'Grady, A Ovcharova, A Picazio, C Pollard, B Potter-Landua, C Potter, S Rappoccio, J Rojo, J Rutherfoord, GP Salam, RM Schabinger, A Schwartzman, MD Schwartz, B Shuve, P Sinervo, D Soper, DES Corral, M Spannowsky, E Strauss, M Swiatlowski, J Thaler, C Thomas, E Thompson, NV Tran, J Tseng, E Usai, L Valery, J Veatch, M Vos, W Waalewijn, J Wacker, C Young

Fully Differential Vector-Boson-Fusion Higgs Production at Next-to-Next-to-Leading Order.

Physical review letters 115 (2015) 082002-

M Cacciari, FA Dreyer, A Karlberg, GP Salam, G Zanderighi

We calculate the fully differential next-to-next-to-leading-order (NNLO) corrections to vector-boson fusion (VBF) Higgs boson production at proton colliders, in the limit in which there is no cross talk between the hadronic systems associated with the two protons. We achieve this using a new "projection-to-Born" method that combines an inclusive NNLO calculation in the structure-function approach and a suitably factorized next-to-leading-order VBF Higgs plus three-jet calculation, using appropriate Higgs plus two-parton counterevents. An earlier calculation of the fully inclusive cross section had found small NNLO corrections, at the 1% level. In contrast, the cross section after typical experimental VBF cuts receives NNLO contributions of about (5-6)%, while differential distributions show corrections of up to (10-12)% for some standard observables. The corrections are often outside the next-to-leading-order scale-uncertainty band.

Use of charged-track information to subtract neutral pileup

PHYSICAL REVIEW D 92 (2015) ARTN 014003

M Cacciari, GP Salam, G Soyez



S Alekhin, O Behnke, P Belov, S Borroni, M Botje, D Britzger, S Camarda, AM Cooper-Sarkar, K Daum, C Diaconu, J Feltesse, A Gizhko, A Glazov, A Guffanti, M Guzzi, F Hautmann, A Jung, H Jung, V Kolesnikov, H Kowalski, O Kuprash, A Kusina, S Levonian, K Lipka, B Lobodzinski, K Lohwasser, A Luszczak, B Malaescu, R McNulty, V Myronenko, S Naumann-Emme, K Nowak, F Olness, E Perez, H Pirumov, R Placakyte, K Rabbertz, V Radescu, R Sadykov, GP Salam, A Sapronov, A Schoening, T Schoerner-Sadenius, S Shushkevich, W Slominski, H Spiesberger, P Starovoitov, M Sutton, J Tomaszewska, O Turkot, A Vargas, G Watt, K Wichmann

Resonance searches with an updated top tagger


G Kasieczka, T Plehn, T Schell, T Strebler, GP Salam

Small-radius jets to all orders in QCD


M Dasgupta, F Dreyer, GP Salam, G Soyez

SoftKiller, a particle-level pileup removal method.

The European physical journal. C, Particles and fields 75 (2015) 59-

M Cacciari, GP Salam, G Soyez

Existing widely used pileup removal approaches correct the momenta of individual jets. In this article we introduce an event-level, particle-based pileup correction procedure, SoftKiller. It removes the softest particles in an event, up to a transverse momentum threshold that is determined dynamically on an event-by-event basis. In simulations, this simple procedure appears to be reasonably robust and brings superior jet resolution performance compared to existing jet-based approaches. It is also nearly two orders of magnitude faster than methods based on jet areas.

Big-Bang Nucleosynthesis

Review of Partical Physics. Chinese Physics C 38 (2014) 090001-

S Sarkar, BD Fields, P Molaro

A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, $\eta$, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of $\eta$ from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range $\eta = (5.7-6.7)\times 10^{-10}$ at 95% CL (corresponding to a cosmological baryon density $\Omega_B h^2 = 0.021 - 0.025$). The D and He-4 abundances, when combined with the CMB determination of $\eta$, provide the bound $N_\nu=3.28 \pm 0.28$ on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

Boosted objects and jet substructure at the LHC. Report of BOOST2012, held at IFIC Valencia, 23rd-27th of July 2012


A Altheimer, A Arce, L Asquith, JB Mayes, EB Kuutmann, J Berger, D Bjergaard, L Bryngemark, A Buckley, J Butterworth, M Cacciari, M Campanelli, T Carli, M Chala, B Chapleau, C Chen, JP Chou, T Cornelissen, D Curtin, M Dasgupta, A Davison, F de Almeida Dias, A de Cosa, A de Roeck, C Debenedetti, C Doglioni, SD Ellis, F Fassi, J Ferrando, S Fleischmann, M Freytsis, ML Gonzalez Silva, S Gonzalez de la Hoz, F Guescini, Z Han, A Hook, A Hornig, E Izaguirre, M Jankowiak, J Juknevich, M Kaci, D Kar, G Kasieczka, R Kogler, A Larkoski, P Loch, DL Mateos, S Marzani, L Masetti, V Mateu, DW Miller, K Mishra, P Nef, K Nordstrom, EO Garcia, J Penwell, J Pilot, T Plehn, S Rappoccio, A Rizzi, G Rodrigo, A Safonov, GP Salam, J Salt, S Schaetzel, M Schioppa, A Schmidt, J Scholtz, A Schwartzman, MD Schwartz, M Segala, M Son, G Soyez, M Spannowsky, I Stewart, D Strom, M Swiatlowski, VS Martinez, M Takeuchi, J Thaler, EN Thompson, NV Tran, C Vermilion, M Villaplana, M Vos, J Wacker, J Walsh

Update of the Binoth Les Houches Accord for a standard interface between Monte Carlo tools and one-loop programs


S Alioli, S Badger, J Bellm, B Biedermann, F Boudjema, G Cullen, A Denner, H van Deurzen, S Dittmaier, R Frederix, S Frixione, MV Garzelli, S Gieseke, EWN Glover, N Greiner, G Heinrich, V Hirschi, S Hoeche, S Alioli, S Badger, J Bellm, B Biedermann, F Boudjema, G Cullen, A Denner, H van Deurzen, S Dittmaier, R Frederix, S Frixione, MV Garzelli, S Gieseke, EWN Glover, N Greiner, G Heinrich, V Hirschi, S Hoeche, J Huston, H Ita, N Kauer, F Krauss, G Luisoni, D Maitre, F Maltoni, P Nason, C Oleari, R Pittau, S Plaetzer, S Pozzorini, L Reina, C Reuschle, T Robens, J Schlenk, M Schoenherr, F Siegert, JF von Soden-Fraunhofen, F Tackmann, F Tramontano, P Uwer, G Salam, P Skands, S Weinzierl, J Winter, V Yundin, G Zanderighi, M Zaro

Update of the Binoth les Houches Accord for a standard interface between Monte Carlo tools and one-loop programs

Computer Physics Communications 185 (2014) 560-571

S Alioli, S Badger, J Bellm, B Biedermann, F Boudjema, G Cullen, A Denner, H Van Deurzen, S Dittmaier, R Frederix, S Frixione, MV Garzelli, S Gieseke, EWN Glover, N Greiner, G Heinrich, V Hirschi, S Höche, J Huston, H Ita, N Kauer, F Krauss, G Luisoni, D Maître, F Maltoni, P Nason, C Oleari, R Pittau, S Plätzer, S Pozzorini, L Reina, C Reuschle, T Robens, J Schlenk, M Schönherr, F Siegert, JF Von Soden-Fraunhofen, F Tackmann, F Tramontano, P Uwer, G Salam, P Skands, S Weinzierl, J Winter, V Yundin, G Zanderighi, M Zaro

We present an update of the Binoth Les Houches Accord (BLHA) to standardise the interface between Monte Carlo programs and codes providing one-loop matrix elements. © 2013 Elsevier B.V. All rights reserved.

Towards an understanding of jet substructure


M Dasgupta, A Fregoso, S Marzani, GP Salam

Scale-invariant resonance tagging in multijet events and new physics in Higgs pair production


M Gouzevitch, A Oliveira, J Rojo, R Rosenfeld, GP Salam, V Sanz