Average ATLAS charged-particle multiplicity

Physics and Performance With 13 TeV Proton Collisions

30th July 2015 – After a shutdown of more than two years, Run 2 of the Large Hadron Collider (LHC) has restarted with proton–proton collisions at a centre-of-mass energy of 13 TeV. This new phase will allow the LHC experiments to explore nature and probe the physical laws governing it at scales never reached before.

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This new result at 13 TeV (red circle) is compared to previous results from ATLAS

Top quarks in Run 2 are spot on

27th July 2015With a precision of just under 14% − currently dominated by our ability to understand how many proton-proton collisions have occurred at ATLAS (i.e. luminosity) − this measurement is able to confirm that quantum chromodynamics, the theory of the strong interaction, still seems to be going strong! 

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Murrough Landon and Manuel discussing results from the beam splashes

From ATLAS Around the World: Triggers (and dark) matter

27th July 2015To the best of our knowledge, it took the Universe about 13.798 billion years to allow funny looking condensates of mostly oxygen, carbon and hydrogen to ponder on their own existence. Some particularly curious specimens became scientists, founded CERN, dug several rings into the ground near Geneva, Switzerland, built the Large Hadron Collider, and also installed a handful of large detectors along the way.

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Lepton transverse momentum distribution from the W→ μν selection

Of mesons and bosons

24th July 2015ATLAS is ready for detailed physics studies. The experiment used early data collected from the LHC’s Run 2 to calibrate its detectors. Measurements of the production and leptonic decay of certain particle resonances have shown that the detectors and software are working as expected. 

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Inclusive-jet cross sections as a function of the jet pT

First measurements set the stage for early searches of new physics

24th July 2015Jets are collimated sprays of hadrons generated from quarks and gluons, produced either directly in the proton-proton collision or as a part of the decay of W bosons, Z bosons, Higgs bosons, top quarks or new particles yet to be discovered. In fact, all W, Z and Higgs bosons decay most often to quarks which form jets. 

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Two-particle correlations

ATLAS measurements of the ridge in proton-proton collisions at 13TeV

24th July 2015Previous studies of two-particle angular correlations in proton-proton, proton-lead, and lead-lead collisions at the LHC have provided important insight on the physics of the particle production process. On 24 July, Atlas presented new preliminary measurements of two-particle correlations...

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The average charged-particle multiplicity as a function of the centre-of-mass energy

Early Run 2 results test event generator energy extrapolation

22nd July 2015On 23 July 2015, ATLAS presented its first measurements of soft strong interaction processes using charged particles produced in proton–proton collisions at 13 TeV centre-of-mass energy delivered by the Large Hadron Collider at CERN. These measurements were performed with a dataset collected beginning of June under special low-luminosity conditions.

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