The 2016 edition of the annual topcites list is still very much dominated by experiment, in particular the discovery of the Higgs boson in 2012, with the ATLAS and CMS papers at the  and  positions as they have been since 2013 (joined by the ATLAS and CMS instrumentation papers [12,13]). Indeed, they have now cracked the top ten of the all time list, where they are the only papers from the 2010s and, together with the 2006 PYTHIA  and 2002 GEANT4  papers, the only papers from this century. The ATLAS and CMS collaborations produced a joint paper in 2015 on the Higgs boson mass and it makes its first appearance in the Top Forty this year . The papers from the 1990s on the AdS/CFT correspondence [5,14,20] continue to be strongly represented. A breakthrough paper from 2006 by Ryu and Takayanagi , which connects entanglement entropy and Bekenstein-Hawking entropy, has made its first appearance in the Top Forty list as interest grows in the connection between quantum information concepts and quantum gravity. Aside from these papers, all of the theoretical papers in the top twenty are resource papers centered around LHC-relevant simulations [4,6,7,8,9,16,19]. The 21st century simulation codes Sherpa and POWHEG make their first appearance on the Top Forty list this year [35,38] following a long, steady climb in their annual citation rates [2008 paper, 2004 paper]. Away from the LHC-zone, observational cosmology rules the top twenty, with familiar favorites [3,10,15,17,18] and one very important newcomer , to which we now turn.
The gravitational wave discovery paper  by the LIGO Scientific and Virgo collaborations appeared simultaneously in Physical Review Letters and on arXiv.org in February. By April it had 200 citations and by July 500 citations. In late December Science Magazine named this discovery the Breakthrough of the Year for 2016. So far this seems to have exerted little influence on the rest of the topcite list (though one can detect an uptick in citations of Einstein’s original GR paper and his 1937 paper on gravitational waves). It will be interesting to see what happens in 2017.
The other big news of 2016 was the possible di-photon (or gamma-gamma) excess reported in December of 2015 by ATLAS  and CMS  in papers that were, unprecedentedly for the Top Forty list, neither arXiv eprints nor journal articles. As a potential signal for New Physics, this precipitated an intense period of research. The observations generated more than 400 theory papers citing the ATLAS and CMS reports. This collection of theory papers acquired a Hirsh index of 92, that is 92 of these citing papers themselves garnered at least 92 citations. Publishing these theory papers was a matter of controversy. JHEP declined for some time to publish any theory paper explaining the resonance; Physical Review Letters chose four to illustrate the ferment in the particle theory community. Finally at the ICHEP conference in Chicago in August it was announced that the signal disappeared when studied in the larger LHC data set accumulated in 2016. In the still-relevant words of Maurice Goldhaber, “not all candidates get elected”.
The remainder of the list includes familiar papers from previous Top Forty lists. On the theory side are more LHC-relevant simulation papers [22,23,25,28,30,31], Hawking radiation , inflation [26,34], large extra dimensions  and neutrino mixing . The list is rounded out by the first resullts from LUX on dark matter  (the final results from LUX appeared in August, too late for this edition) and the update of cosmological parameters from the full WMAP data set .
– Heath O’Connell and Michael Peskin.