Review of Linac-Ring Type Collider Proposals

There are three possibly types of particle colliders schemes: familiar (well known) ring-ring colliders, less familiar however sufficiently advanced linear colliders and less familiar and less advanced linac-ring type colliders. The aim of this paper is two-fold: to present possibly complete list of papers on linac-ring type collider proposals and to emphasize the role of linac-ring type machines for future HEP research.Comment: quality of figures is improved, some misprints are correcte

TeV-scale electron Compton scattering in the Randall-Sundrum scenario

The spin-2 graviton excitations in the Randall-Sundrum gravity model provides a t-channel contribution to electron Compton scattering which competes favourably with the standard QED contributions. The phenomenological implications of these contributions to the unpolarized and polarized cross-sections are evaluated.Comment: 11 pages, 5 figure

Backward scattering of low-energy antiprotons by highly charged and neutral uranium: Coulomb glory

Collisions of antiprotons with He-, Ne-, Ni-like, bare, and neutral uranium are studied theoretically for scattering angles close to 180$^{\circ}$ and antiproton energies with the interval 100 eV -- 10 keV. We investigate the Coulomb glory effect which is caused by a screening of the Coulomb potential of the nucleus and results in a prominent maximum of the differential cross section in the backward direction at some energies of the incident particle. We found that for larger numbers of electrons in the ion the effect becomes more pronounced and shifts to higher energies of the antiproton. On the other hand, a maximum of the differential cross section in the backward direction can also be found in the scattering of antiprotons on a bare uranium nucleus. The latter case can be regarded as a manifestation of the screening property of the vacuum-polarization potential in non-relativistic collisions of heavy particles.Comment: 14 pages, 5 figure

The production of the new gauge boson BHB_{H} via e−γe^{-}\gamma collision in the littlest Higgs model

The new lightest gauge boson $B_H$ with mass of a few hundred GeV is predicted in the littlest Higgs model. $B_H$ should be accessible in the planed ILC and the observation of such particle can strongly support the littlest Higgs model. The realization of $\gamma\gamma$ and $e\gamma$ collision will open a wider window to probe $B_H$. In this paper, we study the new gauge boson $B_{H}$ production processes $e^{-}\gamma\to e^{-}\gamma B_{H}$ and $e^{-}\gamma\to e^{-}Z B_{H}$ at the ILC. Our results show that the production cross section of the process $e^{-}\gamma\to e^{-}Z B_{H}$ is less than one fb in the most parameter spaces while the production cross section of the process $e^{-}\gamma\to e^{-}\gamma B_{H}$ can reach the level of tens fb and even hundreds of fb in the sizable parameter spaces allowed by the electroweak precision data. With the high luminosity, the sufficient typical signals could be produced, specially via $e^{-}\gamma\to e^{-}\gamma B_{H}$. Because the final electron and photon beams can be easily identified and the signal can be easily distinguished from the background produced by $Z$ and $H$ decaying, $B_H$ should be detectable via $e\gamma$ collision at the ILC. Therefore, the processes $e^{-}\gamma\to e^{-}\gamma B_{H}$ and $e^{-}\gamma\to e^{-}Z B_{H}$ provide a useful way to detect $B_{H}$ and test the littlest Higgs model.Comment: 15 pages, 3 figures. Some typos have been corrected, we have added some new references, and there are also some changes in equation 1

ILC Beam Energy Measurement by means of Laser Compton Backscattering

A novel, non-invasive method of measuring the beam energy at the International Linear Collider is proposed. Laser light collides head-on with beam particles and either the energy of the Compton scattered electrons near the kinematic end-point is measured or the positions of the Compton backscattered $\gamma$-rays, the edge electrons and the unscattered beam particles are recorded. A compact layout for the Compton spectrometer is suggested. It consists of a bending magnet and position sensitive detectors operating in a large radiation environment. Several options for high spatial resolution detectors are discussed. Simulation studies support the use of an infrared or green laser and quartz fiber detectors to monitor the backscattered photons and edge electrons. Employing a cavity monitor, the beam particle position downstream of the magnet can be recorded with submicrometer precision. Such a scheme provides a feasible and promising method to access the incident beam energy with precisions of $10^{-4}$ or better on a bunch-to-bunch basis while the electron and positron beams are in collision.Comment: 47 pages, 26 figures, version as accepted by Nucl. Instr. Meth. A after improvement

Electron detachment from negative ions in bichromatic laser field

Negative ion detachment in two-colour laser field is considered within the recent modification of Keldysh model which makes it quantitatively reliable. The general approach is illustrated by calculation of angular differential detachment rates, partial rates for particular ATD (Above Threshold Detachment) channels and total detachment rates for H$^-$ ion in bichromatic field with 1:2 frequency ratio. Both perturbative and strong field regimes are examined. Polar asymmetry and phase effects are quantitatively characterized with some new features revealed. Phase effects are found to result in a huge anisotropy factor $\sim 10^3$ in the electron angular distribution in the perturbative regime.Comment: 13 pages, 8 figures in separate files which are not incorporated in the latex file of the pape

Spontaneous vacuum decay in low-energy collisions of heavy nuclei beyond the monopole approximation

The problem of spontaneous vacuum decay in low-energy collisions of heavy nuclei is considered beyond the scope of the monopole approximation. The time-dependent Dirac equation is solved in a rotating coordinate system with $z$-axis directed along the internuclear line and the origin placed at the center of mass. The probabilities of electron-positron pair creation and the positron energy spectra are calculated in the approximation neglecting the rotational coupling. The two-center potential is expanded over spherical harmonics and the convergence with respect to the number of terms in this expansion is studied. The results show that taking into account the two-center potential instead of its spherically symmetric part preserves all the signatures of the transition to the supercritical regime that have been found in the framework of the monopole approximation and even enhances some of them.Comment: 7 pages, 4 figures, 1 tabl

A study of single sneutrino production in association with fermion pairs at polarised photon colliders

We investigate single sneutrino production in the context of R-parity-violating Supersymmetry at future $\gamma\gamma$ linear colliders. The sneutrino is produced in association with fermion pairs and it is shown that its decays into two further fermions will lead to a clean signal. We also discuss possible backgrounds and the effects of beam polarisation.Comment: 31 pages, LaTeX, 10 postscript figures. Title has been modified. Two new figures and one appendix added. Detailed SM background estimations were made. A new reference added. Version to appear in PR

Compton scattering in Noncommutative Space-Time at the NLC

We study the Compton scattering in the noncommutative counter part of QED (NC QED). Interactions in NC QED have momentum dependent phase factors and the gauge fields have Yang Mills type couplings, this modifies the cross sections and are different from the commuting Standard Model. Collider signals of noncommutative space-time are studied at the Next Linear Collider (NLC) operating in the $e \gamma$ mode. Results for different polarised cases are presented and it is shown that the Compton process can probe the noncommutative scale in the range of 1 - 2.5 TeV for typical proposed NLC energies.Comment: 12 pages, 5 Postscript figures, version to appear in Phys. Rev.

The WW Boson Loop Background to H -> ZZ at Photon-photon Colliders

We have performed a complete one-loop calculation of $\gamma \gamma \rightarrow ZZ$ in the Standard Model, including both gauge bosons and fermions in the loop. We confirm the large irreducible continuum background from the $W$-boson loop found by Jikia. We have included the photon-photon luminosity, and find that the continuum background of transverse $Z$ boson pairs prohibits finding a heavy Higgs with mass \gtap 350 GeV in this decay mode.Comment: 16 pages + 4 PS figures included (uuencoded), MAD/PH/77