Hypothetical low-mass particles, such as axions, provide a compelling explanation for the dark matter in the universe. Such particles are expected to emerge abundantly from the hot interior of stars. To test this prediction, the CERN Axion Solar Telescope (CAST) uses a 9 T refurbished Large Hadron Collider test magnet directed towards the Sun. In the strong magnetic field, solar axions can be converted to X-ray photons which can be recorded by X-ray detectors. In the 2013–2015 run, thanks to low-background detectors and a new X-ray telescope, the signal-to-noise ratio was increased by about a factor of three. Here, we report the best limit on the axion–photon coupling strength (0.66 × 10⁻¹⁰ GeV⁻¹ at 95% confidence level) set by CAST, which now reaches similar levels to the most restrictive astrophysical bounds.

Combined ATLAS and CMS measurements of the Higgs boson production and decay rates, as well as constraints on its couplings to vector bosons and fermions, are presented. The combination is based on the analysis of five production processes, namely gluon fusion, vector boson fusion, and associated production with a W or a Z boson or a pair of top quarks, and of the six decay modes H → ZZ, W W , γγ, ττ, bb, and μμ. All results are reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of the combined measurement by the ATLAS and CMS experiments. The analysis uses the CERN LHC proton-proton collision data recorded by the ATLAS and CMS experiments in 2011 and 2012, corresponding to integrated luminosities per experiment of approximately 5 fb−1 at s√=7s=7 TeV and 20 fb−1 at s√=8s=8 TeV. The Higgs boson production and decay rates measured by the two experiments are combined within the context of three generic parameterisations: two based on cross sections and branching fractions, and one on ratios of coupling modifiers. Several interpretations of the measurements with more model-dependent parameterisations are also given. The combined signal yield relative to the Standard Model prediction is measured to be 1.09 ± 0.11. The combined measurements lead to observed significances for the vector boson fusion production process and for the H → ττ decay of 5.4 and 5.5 standard deviations, respectively. The data are consistent with the Standard Model predictions for all parameterisations considered.BMWF and FWF ; FNRS and FWO ; CNPq, CAPES, FAPERJ, and FAPESP ; MEYS ; CERN ; CAS, MoST, and NSFC ; COLCIENCIAS ; MSES ; RPF ; MoER, SF0690030s09 and ERDF ; Academy of Finland, MEC, and HIP ; CEA and CNRS/IN2P3 ; BMBF, DFG, and HGF ; GSRT ; OTKA and NKTH ; DAE and DST ; IPM ; SFI ; INFN ; NRF and WCU ; LAS ; CINVESTAV, CONACYT, SEP, and UASLP-FAI ; MSI ; PAEC ; MSHE and NSC ; FCT ; JINR ; MSTD ; SEIDI and CPAN ; Swiss Funding Agencies ; NSC ; ThEPCenter, IPST and NSTDA ; TUBITAK and TAEK ; NASU ; STFC ; DOE and NSF ; the Marie-Curie programme and the European Research Council and EPLANET ; the Leventis Foundation ; the A.P. Sloan Foundation ; the Alexander von Humboldt Foundation ; the Belgian Federal Science Policy Office ; the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture ; the Agentschap voor Innovatie door Wetenschap en Technologie ; the Ministry of Education, Youth and Sports of Czech Republic ; the Council of Science and Industrial Research, India ; the Compagnia di San Paolo ; the HOMING PLUS programme of Foundation for Polish Science, cofinanced by EU, Regional Development Fund ; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF ; CSIR ; BSF, GIF, and Minerva ; BRF ; the HOMING PLUS programme of the FPS, co-financed from the EU Regional Development und, the Mobility Plus programme of the MSHE, and the OPUS programme of the NSC ; the NPRP by Qatar NRF ; Generalitat de Catalunya, Generalitat Valenciana, and the Programa Clar´ın-COFUND del Principado de Asturias ; the achadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University, and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project ; the Royal Society and Leverhulme Trust ; the A. P. Sloan Foundation and the Welch Foundation

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New sets of parameters (“tunes”) for the underlying-event (UE) modelling of the pythia8, pythia6 and herwig++Monte Carlo event generators are constructed using different parton distribution...

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