TLEP: A high-Performance Circular $e^{+}e^{-}$ Collider to Study the Higgs Boson

The recent discovery of a light Higgs boson has opened up considerable interest in circular $e^+e^-$ Higgs factories around the world. We report on the progress of the TLEP concept since last year. TLEP is an $e^+e^-$ circular collider capable of very high luminosities in a wide centre-of-mass (ECM) spectrum from 90 to 350 GeV. TLEP could be housed in a new 80 to 100 km tunnel in the Geneva region. The design can be adapted to different ring circumference (e.g. LEP3 in the 27 km LHC tunnel). TLEP is an ideal complementary machine to the LHC thanks to high luminosity, exquisite determination of ECM and the possibility of four interaction points, both for precision measurements of the Higgs boson properties and for precision tests of the closure of the Standard Model from the Z pole to the top threshold