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Possible single productions of the fourth standard model family charged leptons via anomalous interactions at the future ep colliders are studied. Signatures of such anomalous processes and backgrounds are discussed in detail.

Many complex scientific and technical systems demonstrate exponential performance progress with time ∝ e^+t/C. The characteristic progress time C, a measure of empirical difficulty and complexity, is analyzed for high energy elementary particle colliders, astrophysical searches for galaxies and exoplanets, protein structure determination, and compared with computers and thermonuclear fusion reactors. An explanation of the characteristic exponential progress is offered.

The Glashow resonance is a rapid enhancement of the cross-section for scattering of electron antineutrinos on electrons at the $W^{-}$ boson production threshold due to the $s$-channel contribution. This resonance is being searched for at large volume neutrino detectors in which the reaction ${\bar{\nu }}_e{e}^{-}\to W^{-}$ to be initiated by cosmic ray antineutrinos of energies about 6.3 PeV. The relatively small neutrino flux reaching the Earth together with the necessity of analyzing ultra-high-energy final states make such searches challenging. We argue here that the Glashow resonance may contribute to the process $e^{+}{e}^{-}\to W^{+}{W}^{-}$. By extending the method of the effective (equivalent) particles to the neutral leptons, we relate the distribution of the effective neutrinos in the electron to the total cross-section for $e^{+}{e}^{-}\to W^{+}{W}^{-}$. Our approach gives a good fit to the existing experimental data measured at the collider LEP at CERN and allows one to interpret these measurements as an observation of the Glashow resonance. We also discuss an advantage of future electron–positron colliders for probing the resonance.

Uncertainties of the MSSM predictions are due to an unknown SUSY breaking mechanism. To reduce these uncertainties, one usually imposes constraints on the MSSM parameter space. Recently, two new constraints became available, both from astrophysics: WMAP precise measurement of the amount of the Dark Matter in the Universe and EGRET data on an excess in diffuse gamma ray flux. Being interpreted as a manifestation of supersymmetry these data lead to severe constraints on parameter space and single out a very restricted area. The key feature of this area is the splitting of light gauginos from heavy squarks and sleptons. We study the phenomenological properties of this scenario, in particular, the cross-sections of superparticle production, their decay patterns and signatures for observation at hadron colliders, Tevatron and LHC. We found that weakly interacting particles in this area are very light so that the cross-sections may reach fractions of a pb with jets and/or leptons as final states accompanied by missing energy taken away by light neutralino with a mass around 100 GeV.

This talk is an attempt to present the current accelerator field status and assured prospects for elementary particle physics. The discussed subject is so rich that many interesting and important components of the picture are inevitably missing. The talk is updated version of my talk at HEP2005 International Europhysics Conference on High Energy Physics in Lisboa, Portugal.

Prospects for SUSY discoveries and measurements at future colliders LHC and ILC are discussed. The problem of reconstructing the underlying theory and SUSY breaking mechanism is also addressed.

High energy hadron colliders have been in the forefront of particle physics for more than three decades. At present, international particle physics community considers several options for a 100 TeV proton–proton collider as a possible post-LHC energy frontier facility. The method of colliding beams has not fully exhausted its potential but has slowed down considerably in its progress. This paper briefly reviews the accelerator physics and technology challenges of the future very high energy colliders and outlines the areas of required research and development towards their technical and financial feasibility.

I will begin with a brief review of the triumph of Yang–Mills theory at particle accelerators, a development that began some years after their historic paper. This story reached a culmination, or at least local extremum, with the discovery at the Large Hadron Collider of a Higgs-like scalar boson in 2012. The talk then proceeds to a slightly more technical level, discussing how we derive predictions from the gauge field theories of the Standard Model and its extensions for use at high energy accelerators.

In this paper we will give an introduction to the Circular Electron Positron Collider (CEPC). The scientific background, physics goal, the collider design requirements and the conceptual design principle of the CEPC are described. On the CEPC accelerator, the optimization of parameter designs for the CEPC with different energies, machine lengths, single ring and crab-waist collision partial double ring, advanced partial double ring and fully partial double ring options, etc. have been discussed systematically, and compared. The CEPC accelerator baseline and alternative designs have been proposed based on the luminosity potential in relation with the design goals. The CEPC sub-systems, such as the collider main ring, booster, electron positron injector, etc. have also been introduced. The detector and the MAchine-Detector Interface (MDI) design have been briefly mentioned. Finally, the optimization design of the Super Proton–Proton Collider (SppC), its energy and luminosity potentials, in the same tunnel of the CEPC are also discussed. The CEPC-SppC Progress Report (2015–2016) has been published.

The future of the world-wide HEP community critically depends on the feasibility of the concepts for the post-LHC Higgs factories and energy frontier future colliders. Here we overview the accelerator options based on traditional technologies and consider the need for plasma colliders, particularly, muon crystal circular colliders. We briefly address the ultimate energy reach of such accelerators, their advantages, disadvantages and limits in the view of perspectives for the far future of the accelerator-based particle physics and outline possible directions of R&D to address the most critical issues.

Crystals were used at Fermilab accelerators for slow extraction and halo collimation in the Tevatron collider, and for channeling radiation generation experiments at the FAST electron linac facility. Here we overview past experience and major outcomes of these studies and discuss opportunities for new crystal acceleration R&D program.

A strongly coupled Quark–Gluon Plasma (sQGP) is created in the high-energy heavy-ion collisions at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider (LHC). Our present understanding of sQGP as a very good liquid with astonishingly low viscosity is reviewed. With the arrival of the interesting results from LHC in high-energy $p+p$ and $p+A$, a new endeavor to characterize the transition from these small systems to heavy ions $(A+A)$ is now in place, since even the small systems showed prominent similarities to heavy ions in the rising multiplicity domains. An outlook of future possibilities for better measurements is also made at the end of this brief review.

The small collision systems like p+p and p+A collisions have shown new features like A+A collisions in the relativistic regime. These new aspects in small systems which have altered our research and understanding on the two-particle correlation measurements have been provided. Additionally, a critical observation of the fluctuation measurements provides new ways to infer such novel happening in the small collision systems. The ongoing and future endeavors towards the new measurements are also discussed.

It has been postulated that black holes (BHs) could be created in particle collisions within the range of the available energies for nowadays colliders (LHC). In this paper, we analyze the evaporation of a type of BHs that are candidates for this specific behavior, namely, small BHs on a brane in a world with large extra-dimensions. We examine their evolution under the assumption that energy conservation is satisfied during the process and compare it with the standard evaporation approach. We claim that, rather than undergoing a quick total evaporation, BHs become quasi-stable. We comment on the (absence of) implications for safety of this result. We also discuss how the presence of BHs together with the correctness of the energy conservation approach might be experimentally verified.

The physics search potential of the recently proposed FEL ⊗ LHC collider is illustrated in the sample of the collective excitations of the ¹⁵⁴Sm nucleus. In this facility the accelerated fully ionized nuclei will "see" the keV energy FEL photons as a MeV energy laser beam. The main advantages compared to the traditional methods are the tunability, monochromaticity and high polarization of the FEL beam. The advantages result in higher statistics and the possibility to investigate individual levels.

In this brief article I present my memories and impressions of academician G. I. Budker (1918–1977), the brilliant physicist and outstanding leader of scientific research.

A historical review is given of the development of CERN from its foundation to the present from the personal viewpoint of the author.

The success of the first few years of LHC operations at CERN, and the expectation of more to come as the LHC's performance improves, are already leading to discussions of what should be next for both proton–proton and electron–positron colliders. In this discussion I see too much theoretical desperation caused by the so-far-unsuccessful hunt for what is beyond the Standard Model, and too little of the necessary interaction of the accelerator, experimenter, and theory communities necessary for a scientific and engineering success. Here, I give my impressions of the problem, its possible solution, and what is needed to have both a scientifically productive and financially viable future.

High energy ion colliders are large research tools in nuclear physics for studying the quark–gluon–plasma (QGP). The collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead, and uranium. Asymmetric collision combinations (such as protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders: the Relativistic Heavy Ion Collider (RHIC) at BNL and the Large Hadron Collider (LHC) at CERN.