No Arabic abstract
Following a brief review of our contributions to the 2006 European PP Strategy, recent comments on several topics are presented. First of all, it is emphasized that only the simplest version of the fourth chiral generation, namely, minimal SM4 (mSM4) with only one Higgs doublet is in some tension with the recent LHC data on the Higgs boson search. This tension, which follows from the relative strengths of the H --> 4l and Higgs --> {gamma}{gamma} channels, can be naturally resolved if there is a mechanism to enhance the H-->{gamma}{gamma} width (although any charged and heavy particle could enhance the H-{gamma}-{gamma} loop, 2HDM can be given as an example). We then emphasize the possible role of the linac-ring type colliders, especially LHeC (QCD Exploder) and TAC super charm factory. The QCD Explorer will give opportunity to enlighten the origin of the 98.5% portion of the visible universes mass. Especially the {gamma}-nucleus option seems to be very promising for QCD studies. The TAC super charm factory may provide opportunity to investigate the charm physics with statistics well above that of the dedicated runs at Super-B factories. Finally, it is argued that the history of particle physics (and, more generally, the history of the investigation of the fundamental ingredients of the matter), a large number of fundamental particles, an inflation of observable free parameters, and, especially, the mixing of fundamental fermions favor the idea of a new set of fundamental particles at a deeper level. These new particles can be formulated with the preonic or even pre-preonic models.
First of all, an importance of the LHC and FCC based energy frontier lepton-hadron and photon-hadron colliders is emphasised. Then arguments favoring existence of new heavy isosinglet down-type quarks and vector-like isosinglet or isodoublet leptons are presented, following by historical arguments favoring new (preonic) level of matter. The importance of Super-Charm factory and GeV energy proton linac for Turkey national road map is argued. Finally, several recommendations for ESPP2020 are suggested.
TeV center of mass energy lepton-hadron collider is necessary both to clarify fundamental aspects of strong interactions and for adequate interpretation of the LHC data. Recently proposed QCD Explorer utilizes the energy advantage of the LHC proton and ion beams, which allows the usage of relatively low energy electron beam. Two options for the LHC based ep collider are posibble: construction of a new electron ring in the LHC tunnel or construction of an e-linac tangentially to the LHC. In the latter case, which seems more acceptable for a number of reasons, two options are under consideration for electron linac: the CLIC technology allows shorter linac length, whereas TESLA technology gives higher luminosity.
An outline of the physics reasons to pursue a future programme in high-energy colliders is presented.
For more than 30 years [1], gamma-gamma and gamma-electron photon colliders have been considered a natural addition to e+e- linear-collider projects. Following the recent discovery of the Higgs boson, the physics community has been actively considering various approaches to building a Higgs factory, a photon collider (with or without e+e-) being one of them. In this note, following a brief discuss of photon colliders based on ILC and CLIC, I give a critical overview of the recently proposed photon-collider Higgs factories with no e+e- collision option.
We propose and demonstrate that a gamma-gamma collider with W_gg < 12 GeV can be added to the European XFEL with a minimal disruption to its main program. High-energy photons will be obtained by Compton scattering of 0.5 micron laser photons on the existing 17.5 GeV electron beams. Such a gamma-gamma collider would be an excellent place for the development and application of modern technologies: powerful lasers, optical cavities, superconducting linacs, and low-emittance electron sources -- as well as training the next generation of accelerator physicists and engineers. The physics program would include spectroscopy of C=+ resonances in various J^P states bbar{b}, cbar{c}, four-quark states, quark molecules and other exotica) in a mass range barely scratched by past and not covered by any current or planned experiments. Variable circular and linear polarizations will help in the determination of quantum numbers and measurement of polarization components of the gamma-gamma cross section (sigma_perp, sigma_parallel, sigma_0, sigma_2).