Introduction to the Photon Collider

The purpose of this Introduction, presented at PHOTON2007, is to provide an overview of the basic principles, possible parameters, some technical aspects and the physics program of the photon collider and discuss its status within the ILC project.Comment: Talk at Photon2007, Paris, July 9-13, 2007, to be published in Nucl. Phys. B, 17 pp, Latex, 10 .eps figure

Precision luminosity measurement at LHC using two-photon production of mu^+ mu^- pairs

The application of the two-photon process pp -> pp + mu^+mu^- for the luminosity measurements at LHC with the ATLAS detector is considered. The expected accuracy of the absolute offline luminosity determination is 1 - 2 % for the luminosity range of 10^{33} - 10^{34} cm^-2 s^-1. The preliminary cross section estimates done for LHCb promise the same level of the luminosity measurement accuracy at L = 2 x 10^{32} cm^-2 s^-1.Comment: 10 pages, Latex, 5 figures (9 .eps files). Talk at the VIII Intern. Conference on Instrumentation for Colliding Beam Physics, Novosibirsk, Russia, Feb.28 - March 6, 2002, be published in Nucl. Instrum. and Methods

Is a laser "wire" a non-invasive method?

A tightly focused laser beam (laser wire) is used for measurement of transverse electron beam sizes in storage rings and linear colliders. It is assumed that the laser beam does nothing with the electron beam except Compton scatterings which happen with a rather small probability. In reality, electrons crossing the laser beam get kicks (with 100 % probability) proportional to the square of the laser field and inversely proportional to the beam energy. In practical cases of beam diagnostics this effect is negligible.Comment: 3 pages, Latex. Talk at 26-th Advanced ICFA Beam Dynamic Workshop on Nanometre-Size Colliding Beams (Nanobeam2002), Lausanne, Switzerland, Sept 2-6, 2002. v.2 small editorial corrections, journal version. To be published in Nucl. Instr. and Methods

Determination of the Higgs-boson couplings and H-A mixing in the generalized SM-like Two Higgs Doublet Model

The feasibility of measuring the Higgs-boson properties at the Photon Collider at TESLA has been studied in detail for masses between 200 and 350 GeV, using realistic luminosity spectra and detector simulation. We consider the Two Higgs Doublet Model (II) with SM-like Yukawa couplings for h, parametrized by only one parameter (tan(beta)). The combined measurement of the invariant-mass distributions in the ZZ and W+W- decay-channels is sensitive to both the two-photon width Gamma_{gamma gamma} and phase Phi_{gamma gamma}. From the analysis including systematic uncertainties we found out that after one year of Photon Collider running with nominal luminosity the expected precision in the measurement of tan(beta) is of the order of 10%, for both light (h) and heavy (H) scalar Higgs bosons. The H-A mixing angle Phi_{HA}, characterizing a weak CP violation in the model with two Higgs doublets, can be determined to about 100 mrad, for low tan(beta).Comment: 17 pages, 9 figures; published versio

Study of the Higgs-boson decays into WW and ZZ at the Photon Collider

Production of the Standard Model Higgs-boson at the Photon Collider at TESLA is studied for the Higgs-boson masses above 150 GeV. Simulation of signal and background processes takes into account realistic luminosity spectra and detector effects. In the considered mass range, large interference effects are expected in the W+W- decay channel. By reconstructing W+W- and ZZ final states, not only the h->gamma gamma partial width can be measured, but also the relative phase of the scattering amplitude. This opens a new window for the precise determination of the Higgs-boson couplings. Models with heavy, fourth-generation fermions and with enlarged Higgs sector (2HDM (II)) are considered.Comment: 19 pages, 18 figures; updated version with improved precision of estimate

ZZγZZ\gamma and ZγγZ\gamma\gamma couplings in γe\gamma e collision with polarized beams

The potential of $\gamma$e mode of linear $e^{+}e^{-}$ collider to probe $ZZ\gamma$ and $Z\gamma\gamma$ vertices is investigated through the Z boson production from the procees $\gamma e\to Z e$. Considering the longitudinal and transverse polarization states of the Z boson and incoming polarized beams we find the 95% C.L. limits on the form factors $h_{3}^{Z}$, $h_{4}^{Z}$, $h_{3}^{\gamma}$ and $h_{4}^{\gamma}$ with integrated luminosity 500$fb^{-1}$ and $\sqrt{s}=$0.5, 1, 1.5 TeV energies. It is shown that the polarization can improve sensitivities by factors 2-3 depending on the energy.Comment: 12 pages, 8 EPS figure

TESLA: Potentials of γγ\gamma\gamma and e+e−e^+e^- Options in Stoponium Searches

In some supersymmetric extensions of the Standard Model fairly light superpartner of t-quark is predicted, which may form bound states - stoponiums. We estimate potentials of TESLA linear collider in search for stoponium, considering the basic e+e- option and the gamma-gamma option (Photon Linear Collider - PLC). It is found that PLC could be the best machine for discovery of these new narrow strong resonances. It can produce thousands stoponiums per 100 fb$^-1$ integrated luminosity in the high energy peak. In the case of scenarios when stoponium decays mainly into gluons the signal/background ratio is about 1/4. The channel S->hh into two lightest Higgs bosons could be also seen with high significance. Thus, several weeks run is sufficient for the stoponium discovery, if its mass is approximately known (e.g. from observation of direct stops production at LHC). Then, in MSSM scenarios with dominant S->hh decay PLC shows excellent possibilities to discover bound state of stops, practically immediately after beginning of operating. The e+e- option also has some prospects to observe stoponium but only in the case of scenarios with dominant decay into two lightest Higgs bosons, with tens of events per 100 $fb^{-1}$. Interesting possibility appears in the case when the resonance is seated on 0.1% width luminosity peak - one could resolve the stoponium exited states.Comment: Standard LaTeX, 15 pages, 2 figures, uses elsart.cls. Talk at the International Workshop on High Energy Photon Colliders (GG2000, DESY, Hamburg, June 14-17, 2000), to be published in Nucl. Instr. and Meth. A. Numbers for e+e- production are change

Compact electron linac LU-7-2 for radiography of large-scale objects

At RFNC-VNIIEF there was started up a compact LU-7-2 linear electron accelerator designed for industrial application in the field of radiography of objects with a large mass thickness as well as for development of radiation technologies. For accelerator microwave power supply there was used a magnetron operating on a wavelength of 10.7 cm with a pulse power of 2.5 MW. Accelerating structure was created on the basis of a circular disc-loaded waveguide with varying geometry of accelerating cells, operating on a traveling wave of 2π/3 mode. Electrons are injected by a diode type 50 kV electron gun. The achieved parameters allow to use the accelerator for radiography of objects with a large mass thickness

Development of radiation technologies on VNIIEF LU-10-20 linac

In the present article there is given a review of a number of last works conducted at VNIIEF with the use of this accelerator

Using Scalars to Probe Theories of Low Scale Quantum Gravity

Arkani-Hamed, Dimopoulos and Dvali have recently suggested that gravity may become strong at energies near 1 TeV which would remove the hierarchy problem. Such a scenario can be tested at present and future colliders since the exchange of towers of Kaluza-Klein gravitons leads to a set of new dimension-8 operators that can play important phenomenological roles. In this paper we examine how the production of pairs of scalars at $e^+e^-$, $\gamma \gamma$ and hadron colliders can be used to further probe the effects of graviton tower exchange. In particular we examine the tree-level production of pairs of identical Higgs fields which occurs only at the loop level in both the Standard Model and its extension to the Minimal Supersymmetric Standard Model. Cross sections for such processes are found to be potentially large at the LHC and the next generation of linear colliders. For the $\gamma\gamma$ case the role of polarization in improving sensitivity to graviton exchange is emphasized.Comment: 32 pages, 12 figures, latex, remarks added to tex