abstract

After a brief description of the basic principle of a photon collider, we summarize the physics potential of such a facility at high energies. Unique opportunities are provided in supersymmetric theories for the discovery of heavy scalar and pseudoscalar Higgs bosons as well as selectrons and \(e\)-sneutrinos.

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Particle physics is entering an exciting time. In the coming years accelerator experiments together with particle and astroparticle physics observations can shed light on many key questions in particle physics and cosmology which are unanswered today. Together with the LHC the ILC will play a crucial role in this respect. This contribution deals with the ILC project comprising physics case, detector studies and accelerator development.

abstract

This paper is the second part of my overview on photon colliders given at the conference “The photon: its first hundred years and the future” (PHOTON2005 + PLC2005). The first paper V.I. Telnov, The photon colliders: the first 25 years, proceedings of PHOTON2005 and PLC2005, Warsaw and Kazimierz, Poland, 30 August–4 September 2005, volume 1, describes the first 25 years of the history and evolution of photon colliders. The present paper considers the photon collider at the ILC: possible parameters, technical problems and present status.

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We consider emission of a photon by an electron in the field of a strong laser wave and production of \(e^+e^-\) pair by a high-energy photon in the field of a strong laser wave. A probability of these processes for circularly or linearly polarized laser photons and for arbitrary polarization of all other particles is calculated. We obtain the complete set of functions which describes such a probability in a compact invariant form. Besides, we discuss the polarization effects in the kinematics relevant to the problem of \(e\to \gamma \) conversion at \(\gamma \gamma \) and \(\gamma e\) colliders.

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The lepton flavour violating (LFV) reactions \({\gamma \gamma \to \ell \ell '}\) (\({\ell ,\ell ^\prime = e, \mu ,\tau }\), \(\ell \ne \ell '\)) which arise at the one loop order of perturbation theory are studied at energies of interest for the \(\gamma \gamma \) option of the future ILC. The LFV mechanism is provided by low energy \(R\)-conserving SUSY with non diagonal slepton mass matrices. The average slepton masses \({\widetilde {m}}\) and the off diagonal matrix elements \(\Delta m\) are treated as model independent free phenomenological parameters in order to discover regions in the parameter space, where the signal cross section may be observable, comparing to the existing bounds on these parameters provided by the non-observation of radiative LFV decays and discuss how to reduce the standard model background.

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We consider the possibility of using \(t\bar t\) production at photon colliders as a probe for physics beyond the Standard Model. The angular and energy distributions of top-quark decay products are employed in the analysis that determines the accuracy with which the new physics parameters can be measured.

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We discuss a model for total hadronic and photonic cross-sections which includes hard parton–parton scattering to drive the rise and soft gluon resummation to tame it. Unitarity is ensured by embedding the cross-section in the eikonal formalism. Predictions for LHC and ILC are presented.

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The target mass dependence of the sum rule for the polarized virtual photon structure function \(g_1^\gamma (x,Q^2,P^2)\) is studied when \(P^2\), the mass squared of the target photon, changes from on-shell to far off-shell. Also the sum rule for another polarized structure function \(g_2^\gamma (x,Q^2,P^2)\) is analyzed in Parton Model (PM). It is found that the first moment of \(g_2^\gamma \) calculated in PM vanishes independent of \(Q^2\), \(P^2\) and quark mass.

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This talk consists of two parts. In the first, the present experimental bounds on the anomalous couplings of the gauge bosons, based mainly on the LEP and Tevatron experiments, are reviewed. In the second part, the theorem of helicity conservation (HC) is presented, which should be valid in either the Standard Model (SM) or MSSM, for any two-body process at high energies and fixed angles. The energy-range for the HC validity is discussed and, under certain conditions, it should well be within the LHC or ILC range. Since all known anomalous couplings violate HC, its testing may provide a way for generically identifying the possible presence of anomalous (non-renormalizable) contributions.

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The various search modes for the Higgs bosons of the Standard Model (SM) and its Minimal Supersymmetric Extension (MSSM) at the International Linear Collider (ILC) will be summarized briefly. In particular, as a unique discovery mode the production of heavy neutral MSSM Higgs bosons for medium values of \(\tan \beta \) in photon collisions will be presented. Furthermore, \(\tau ^+\tau ^-\) fusion into MSSM Higgs bosons in the photon mode will be shown to give access to the mixing parameter \(\tan \beta \) with a precision of better than 10% for large values of this parameter.

abstract

In this talk I will begin with a very brief discussion as to why TeV scale Supersymmetry forms an important subject of the studies at all the current and future Colliders. Then, I will give different examples where the Photon Linear Collider, PLC, will be able to make unique contributions. PLC’s most important role is in the context of Higgs Physics, due to its ability of accurate determination of \({\mit \Gamma }_{\gamma \gamma }\) as well as the possibilities it offers for the determination of the CP property of the Higgs boson and of possible CP-mixing in the Higgs sector. Further, the PLC can provide probes of SUSY in the regions of the SUSY parameter space, which are either difficult or inaccessible at the LHC and also in the \(e^+e^-\) mode of the International Linear Collider (ILC).

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After giving a brief overview of the Standard Model status, I survey physics beyond the Standard Model at the TeV scale, focusing on Technicolour, Little Higgs, Extra Dimensions and Supersymmetry including the MSSM, NMSSM and ESSM.

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The same physical reality in Two Higgs doublet model (2HDM) can be described by different Lagrangians. We study this property called by the reparametrization invariance (in space of Lagrangians). We consider the \(Z_2\)-symmetry of the Lagrangian, which prevents a \(\phi _1\leftrightarrow \phi _2\) transitions, and the different levels of its violation, soft and hard. We argue that softly \(Z_2\) violated 2HDM is a natural model in the description of EWSB. We consider different vacua in the 2HDM. We find simple condition for a CP violation in the Higgs sector. In the Model II for Yukawa interactions we obtain the set of relations among the couplings to gauge bosons and to fermions which allows one to analyse different physical situations (including CP violation) in terms of these very couplings, instead of the parameters of Lagrangian. We discuss possible interaction of Higgs fields of the SM or 2HDM with the inflatory scalar field describing an exponential expansion of Universe after Big Bang.

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Prospects for precise determination of the Higgs boson couplings from a combined analysis of LHC, ILC and the Photon Linear Collider data are studied in detail for the CP-conserving Two Higgs Doublet Model (II). LHC, ILC and the Photon Collider measurements are complementary, being sensitive to different coupling combinations. For the mass of the heavy scalar Higgs boson between 200 and 350 GeV, where \(ZZ\) and \(W^{~+} W^{~-}\) decay-channels dominate, only the combined analysis of the LHC, ILC and the Photon Collider data allows for unique determination of the basic Higgs boson couplings and for establishing evidence for the possible CP violation in 2HDM. Additional constraints on the model parameters can be obtained by combining available data for the production and decays of the heavy Higgs boson \(H\) with the corresponding measurements for the light Higgs boson \(h\).

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We present results on the simulation of the processes which are a background for an intermediate mass Standard Model Higgs production in photon collisions.

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Analysis of the heavy neutral MSSM Higgs bosons production at the Photon Collider is presented for \(M_{A}=200\), 250, 300 and 350 GeV in the parameter range corresponding to the so called “LHC wedge” and beyond. The expected precision of the cross section measurement for the process \(\gamma \gamma \rightarrow A, H \rightarrow b\bar b\) is evaluated for different MSSM scenarios. The analysis takes into account all relevant theoretical and experimental issues which could affect the measurement. For \(\tan \beta =7\) the statistical precision of the cross-section determination is estimated to be 8–34%, after one year of Photon Collider running, for four considered MSSM parameters sets. As heavy neutral Higgs bosons in these scenarios may not be discovered at LHC or at the first stage of the \(e^+ e^-\) collider, an opportunity of being a discovery machine is also studied for the Photon Collider.

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It is shown that the difference in the momentum distributions of positively (\(\mu ^+\), \(e^+\)) and negatively (\(\mu ^-\), \(e^-\)) charged leptons in the reactions of type \(\gamma \gamma \to \mu ^+\mu ^- + N\nu \), \(\gamma \gamma \to W^\pm \mu ^\mp + N\nu \) at \(\sqrt {s}\gt 200\) GeV with polarized photons demonstrates a considerable charge asymmetry of muon distributions, sensitive to New Physics effects. Contribution of processes with intermediate \(\tau \)-lepton in \(\gamma \gamma \to W^\pm \mu ^\mp + N\nu \) is taken into account.

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We report a Monte Carlo study of the \(\gamma \gamma \rightarrow \tilde {\mu }^{\pm }_{\rm R,L}\tilde {\mu }^{\mp }_{\rm R,L}\) reactions. The case of the left-handed scalar lepton is of particular interest because their main decay channel can be measured with a high precision. Final states containing up to 4 leptons and missing energy are also investigated. There, exotic shapes of the energy distributions appear as a consequence of cascade decay which would give a hint to recognize supersymmetric processes by observing the shape of such distributions.

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Based on the possibility of having highly polarized neutralinos in reconstructed rest frames, we show in a systematic way a method of verifying the Majorana nature of neutralinos and testing the CP properties of the neutralino sector of the MSSM in three-body leptonic decays of neutralinos.

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Reconstruction of the fundamental supersymmetric theory and its breaking mechanism will require high-precision tools. Here a brief introduction to SPA, the Supersymmetry Parameter Analysis (SPA) Convention and Project, is presented which is based on a consistent set of conventions and input parameters.

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I will begin by making a few general comments on the synergy between the Large Hadron Collider (LHC) which will go in action in 2007 and the International Linear Collider (ILC) which is under planning. I will then focus on the synergy between the LHC and the PLC option at the ILC, which is expected to be realised in the later stages of the ILC program. In this I will cover the possible synergy in the Higgs sector (with and without CP violation), in the determination of the anomalous vector boson couplings and last but not least, in the search for extra dimensions and radions.

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The OPERA experiment is dedicated to the direct observation of \(\nu _{\tau }\) neutrinos in the long baseline \(\nu _{\mu }\) CNGS beam. Here, a general description of the OPERA detector and its physics performance is presented, the preliminary test results with underground cosmic muons are shown as well.

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This article describes shortly the Liquid Argon TPC detection technique used in ICARUS experiment and discusses the results of tests of the ICARUS detector. Some future prospects of LAr TPC technique are also presented.

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Issues concerning the detector at a possible photon collider are presented. This concerns the design of the forward region, backgrounds in the central detectors, pileup events and the neutron flux from the beam dump.

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Within a future photon-collider based on the infrastructure of ILC the energy of near-infrared laser photons will be boosted by Compton backscattering on a high energy electron beam to well above 100 GeV. By reason of luminosity, an extremely powerful lasersystem is required that will exceed today’s state-of-the-art capabilities. An auxiliary cavity for resonantly enhancing the optical peak-power can relax demands on the power output of the laser. In this paper a possible design and the static aspects of a passive cavity are discussed.

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Despite many technological difficulties the group III nitrides: GaN, AlN and InN and their alloys are primary candidates for electro-optical coherent light sources. In the recent years the research and technology of the nitride based continuous wave (CW) laser diodes (LDs) led to creation of blue-violet coherent light sources of power up to 200 mW. The progress has been attained by using various ways to attack the main obstacles in the technology of these devices such as insufficient size of high quality lattice matched substrates, low \(p\)-doping efficiency of Mg acceptor, poor contact to \(p\)-type semiconductor and low efficiency of radiative recombination. The two different approaches were used to overcome the substrate problem: hetero-epitaxy and homoepitaxy. Homoepitaxy used high pressure GaN high quality crystals. Heteroepitaxy used sapphire, SiC or GaAs substrates and very sophisticated techniques of reduction of the dislocation density. The low \(p\)-doping efficiency by using Mg acceptor is related to creation of Mg–H complexes due to hydrogen presence during the growth of laser diode quantum structures. In addition, Mg acceptor has low efficiency due to its high energy. High Mg concentrations can be obtained by using either MOCVD or ammonia source MBE growth. An alternative route is to use hydrogen-free plasma activated MBE (PA-MBE) method. The recent advances and the prospects of both approaches will be discussed. Solid AlGaInN solution offers a possibility to cover wide spectral range, starting from near UV to blue, green and red. Arsenide based laser diodes (LDs) are efficient coherent red light sources. Therefore, nitride based LDs are considered to be devices of choice for green, blue and UV spectral range. So far only blue and violet laser has been realized. The progress toward green and UV lasers is far less spectacular. The results in all these areas and future prospects will be discussed.

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This article presents a personal summary of the physics case for a photon collider at the ILC and the necessary steps to get this machine.

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The photon collider option is a major addition to the physics scope of the International Linear Collider. In the coming years there will need to be a development and demonstration of the laser systems required as well as a plan for the accelerator layout needed to accommodate the photon collider option. The outstanding technical issues for the photon collider are summarized in this note.

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The “famous formula” \(E = mc^2\) and the concept of “relativistic mass” increasing with velocity, which follows from it, are historical artifacts, contradicting the basic symmetry of Einstein’s Special Relativity. The relation discovered by Einstein is not \(E = mc^2\), but \(E_0 = mc^2\), where \(E_0\) is the energy of a free body at rest. The source of the longevity of the “famous formula” is irresponsible attitude of relativity theory experts to the task of explaining it to the non-experts.

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This small review is devoted to \(\gamma \gamma \) collisions including methods of creating the colliding \(\gamma \gamma \) beams of high energy and physical problems which can be solved or clarified in such collisions.

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I review the potential astrophysical sources observable by the high frequency gravitational wave observatories.

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The X-rays emitted by accreting black holes and neutron stars are modulated quasi-periodically at very high frequencies. These kHz Quasi Periodic Oscillations (QPOs) often occur in pairs of frequencies that in black hole sources are in a 3:2 ratio. The frequencies likely represent two resonant oscillations of the accretion disk. We have evidence that the neutron star data point to the same ratio, and arguments suggesting that the 3:2 frequency ratio may be a signature of strong gravity. The modulation itself of the X-ray light curve may be caused by another effect of general relativity: light-bending close to the black hole. In some neutron star sources, the difference of the two kHz frequencies is very nearly equal to one-half of the stellar spin frequency, which is a clear signature of a non-linear resonance excited by the rotating neutron star.

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We discuss the tests of the fundamental properties of the Standard Model Higgs boson that can performed in the next round of experiments.