First Look at the Physics Case of TLEP

M. Bicer (Faculty of Science, Ankara University, Ankara, Turkey)
H. Duran Yildiz (IAT, Ankara University, Ankara, Turkey)
I. Yildiz (Middle East Technical University, Ankara, Turkey)
G. Coignet, M. Delmastro (Laboratoire d’Annecy-Le-Vieux de Physique des Particules, IN2P3/CNRS, Annecy-Le-Vieux, France)
T. Alexopoulos (National Technical University of Athens, Athens, Greece)
C. Grojean (Institucio Catalana de Recerca i Estudis, Barcelona, Spain)
S. Antusch (Universität Basel, Basel, Switzerland)
T. Sen (Fermilab, Batavia IL, United States)
H.-J. He (Tsinghua University, Beijing, China)
K. Potamianos (Lawrence Berkeley National Laboratory (LBNL), Berkeley CA, United States)
S. Haug (AEC-LHEP, University of Bern, Switzerland)
A. Moreno (Universidad Antonio Narino, Bogota, Colombia)
A. Heister (Boston University, Boston, United States)
V. Sanz (University of Sussex, Brighton, United Kingdom)
G. Gomez-Ceballos, M. Klute, M. Zanetti (MIT, Cambridge MA, United States)
L.-T. Wang (University of Chicago, Chicago IL, United States)
M. Dam (Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark)
C. Boehm, N. Glover, F. Krauss, A. Lenz (Institute for Particle Physics Phenomenology, Durham University, Durham, United Kingdom)
M. Syphers (Michigan State University, East Lansing MI, United States)
C. Leonidopoulos (University of Edinburgh, Edinburgh, United Kingdom)
V. Ciulli, P. Lenzi, G. Sguazzoni (INFN, Sezione di Firenze, Italy)
M. Antonelli, M. Boscolo, O. Frasciello, C. Milardi, G. Venanzoni, M. Zobov (INFN, Laboratori Nazionali di Frascati, Frascati, Italy)
J. van der Bij (Albert-Ludwigs Universität, Freiburg, Germany)
M. de Gruttola (University of Florida, Gainesville, United States)
D.-W. Kim (Gangneung-Wonju National University, Gangneung, South Korea)
M. Bachtis, A. Butterworth, C. Bernet, C. Botta, F. Carminati, A. David, D. d’Enterria, G. Ganis, B. Goddard, G. Giudice, P. Janot, J. M. Jowett, C. Lourenço, L. Malgeri, E. Meschi, F. Moortgat, P. Musella, J. A. Osborne, L. Perrozzi, M. Pierini, L. Rinolfi, A. de Roeck, J. Rojo, G. Roy, A. Sciabà, A. Valassi, C.S. Waaijer, J. Wenninger, H. Woehri, F. Zimmermann (CERN, Geneva, Switzerland)
A. Blondel, M. Koratzinos, P. Mermod (University of Geneva, Geneva, Switzerland)
Y. Onel (University of Iowa, Iowa City IA, United States)
R. Talman (Cornell University, Ithaca NY, United States)
E. Castaneda Miranda (University of Johannesburg, Johannesburg, South Africa)
E. Bulyak (NSC KIPT, Kharkov, Ukraine)
D. Porsuk (Dumlupinar University, Kutahya, Turkey)
D. Kovalskyi, S. Padhi (University of California San Diego, La Jolla CA, United States)
P. Faccioli (LIP, Lisbon, Portugal)
J. R. Ellis (King’s College, London, United Kingdom)
M. Campanelli (University College London, London, United Kingdom)
Y. Bai (University of Wisconsin, Madison WI, United States)
M. Chamizo (CIEMAT, Madrid, Spain)
R.B. Appleby, H.Owen (University of Manchester, Cockcroft Institute, Manchester, United Kingdom)
H. Maury Cuna (Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mérida, México)
C. Gracios, G. A. Munoz-Hernandez (CONACYT, México, México)
L. Trentadue (INFN, Sezione di Milano Bicocca, Italy)
E. Torrente-Lujan (IFT, University of Murcia, Murcia, Spain)
S. Wang (Thomas Jefferson National Accelerator Facility, Newport News VA, United States)
D. Bertsche (University of Oklahoma, Department of Physics and Astronomy, Norman OK, United States)
A. Gramolin, V. Telnov (Budker Institute of Nuclear Physics and Novosibirsk University, Novosibirsk, Russia)
P. Petroff (Laboratoire de l’Accélérateur Linéaire, IN2P3/CNRS, Orsay, France)
P. Azzi (INFN, Sezione di Padova, Italy)
O. Nicrosini, F. Piccinini (INFN, Sezione di Pavia, Italy)
G. Montagna (Università di Pavia, Pavia, Italy)
F. Kapusta, S. Laplace, W. da Silva (Laboratoire de Physique Nucléaire et des Hautes Energies, IN2P3/CNRS, Paris, France)
N. Gizani (Hellenic Open University, Patra, Greece)
N. Craig (Rutgers University, Piscataway NJ, United States)
T. Han (University of Pittsburgh, Pittsburgh PA, United States)
C. Luci, B. Mele, L. Silvestrini (INFN, Università degli Studi La Sapienza, Roma, Italy)
M. Ciuchini (INFN, Sezione di Roma Tre, Roma, Italy)
R. Cakir (Recep Tayyip Erdogan University, Rize, Turkey)
R. Aleksan, F. Couderc, S. Ganjour, E. Lançon, E. Locci, P.  Schwemling, M. Spiro, C. Tanguy, J. Zinn-Justin (CEA, IRFU, Saclay, France)
S. Moretti (University of Southampton, Southampton, United Kingdom)
M. Kikuchi, H. Koiso, K. Ohmi, K. Oide (KEK, Tsukuba, Japan)
G. Pauletta (Università di Udine, Udine, Italy)
R. Ruiz de Austri (Instituto de Fisica Corpuscular (IFIC), Valencia, Spain)
M. Gouzevitch (Institut de Physique Nucléaire de Lyon, IN2P3/CNRS, Villeurbanne, France)
S. Chattopadhyay (Cockcroft Institute, Warrington, United Kingdom)


The discovery by the ATLAS and CMS experiments of a new boson with mass around 125 GeV and with measured properties compatible with those of a Standard-Model Higgs boson, coupled with the absence of discoveries of phenomena beyond the Standard Model up to scales of several hundred GeV, has triggered interest in ideas for future Higgs factories. A new circular \({\rm e}^{+}{\rm e}^{-}\) collider hosted in a 80 to 100 km tunnel, TLEP, is among the most attractive solutions proposed so far. It has a clean experimental environment, produces high luminosity for top-quark, Higgs boson, W and Z studies, accommodates multiple detectors, and can reach energies up to the \({\rm t}\bar{\rm t}\) threshold and beyond. It will enable measurements of the Higgs boson properties and of Electroweak Symmetry-Breaking (EWSB) parameters with unequalled precision, offering exploration of physics beyond the Standard Model in the multi-TeV range. Moreover, being the natural precursor of the VHE-LHC, a 100 TeV hadron machine in the same tunnel, it builds up a long-term vision for particle physics. Altogether, the combination of TLEP and the VHE-LHC offers, for a great cost effectiveness, the best precision and the best search reach of all options presently on the market. This paper presents a first appraisal of the salient features of the TLEP physics potential, to serve as a baseline for a more extensive design study.



The Higgs boson with mass around 125 GeV recently discovered by the ATLAS and CMS experiments (Aad 2012, Chatrchyan 2012) at the LHC is found to have properties compatible with the Standard Model predictions (ATLAS 2013, Chatrchyan 2013), as shown for example in Fig. \ref{fig:ellis} (Ellis 2013). Coupled with the absence of any other indication so far for new physics at the LHC, be it either through precision measurements or via direct searches, this fundamental observation seems to push the energy scale of any physics beyond the Standard Model above several hundred GeV. The higher-energy LHC run, which is expected to start in 2015 at \(\sqrt{s}\sim 13\)-\(14\) TeV, will extend the sensitivity to new physics to 1 TeV or more. Fundamental discoveries may therefore be made in this energy range by 2017-2018. Independently of the outcome of this higher-energy run, however, there must be new phenomena, albeit at unknown energy scales, as shown by the evidence for non-baryonic dark matter, the cosmological baryon-antibaryon asymmetry and non-zero neutrino masses, which are all evidence for physics beyond the Standard