Signals from extra dimensions decoupled from the compactification scale

Multilocalization provides a simple way of decoupling the mass scale of new physics from the compactification scale of extra dimensions. It naturally appears, for example, when localization of fermion zero modes is used to explain the observed fermion spectrum, leaving low energy remnants of the geometrical origin of the fermion mass hierarchy. We study the phenomenology of the simplest five dimensional model with order one Yukawa couplings reproducing the standard fermion masses and mixing angles and with a light Kaluza-Klein quark Q_{2/3} saturating experimental limits on V_{tb} and m_Q, and then with observable new effects at Tevatron.Comment: 18 pages, 7 figs; v2 reference and comments added to match the published version. A discussion of the limits from precision electroweak data is included. Conclusions are unchange

Large extra dimension effects in Higgs boson production at linear colliders and Higgs factories

In the framework of quantum gravity propagating in large extra dimensions, the effects of virtual Kaluza-Klein graviton and graviscalar interference with Higgs boson production amplitudes are computed at linear colliders and Higgs factories. The interference of the almost-continuous spectrum of the KK gravitons with the standard model resonant amplitude is finite and predictable in terms of the fundamental D-dimensional Plank scale M_D and the number of extra dimensions \delta. We find that, for M_D ~ 1 TeV and \delta=2, effects of the order of a few percent could be detected for heavy Higgs bosons (m_H>500 GeV) in Higgs production both via WW fusion in e^+e^- colliders and at \mu^+\mu^- Higgs-boson factories.Comment: 16 pages, 2 figures ; a few comments and references added ; version to appear in JHE

Single Photon Signals for Warped Quantum Gravity at a Linear e+-e- Collider

We study the `single photon' process e+- e- -> gamma nu nubar with contributions due to exchange of massive gravitons in the Randall- Sundrum model of low-scale quantum gravity. It is shown that for significant regions in the parameter space, this process unambiguously highlights the resonance structure of the graviton sector. Even in the non-resonant part of the parameter space, we show that comparison with the benchmark process e+- e- -> mu+- mu- can clearly distinguish signals for warped gravity from similar signals for large extra dimensions.Comment: Published version; figures change

Requirements on collider data to match the precision of WMAP on supersymmetric dark matter

If future colliders discover supersymmetric particles and probe their properties, one could predict the dark matter density of the Universe and would constrain cosmology with the help of precision data provided by WMAP and PLANCK. We investigate how well the relic density can be predicted in minimal supergravity (mSUGRA), with and without the assumption of mSUGRA when analysing data. We determine the parameters to which the relic density is most sensitive, and quantify the collider accuracy needed. Theoretical errors in the prediction are investigated in some detail.Comment: 42 pages, 16 figures. v2 incorporates referee's comments: minor corrections/clarifications with additional figures to show regions of m12-m0 plane considere

A simple method for the determination of the structure of ultrashort relativistic electron bunches

In this paper we propose a new method for measurements of the longitudinal profile of 100 femtosecond electron bunches for X-ray Free Electron Lasers (XFELs). The method is simply the combination of two well-known techniques, which where not previously combined to our knowledge. We use seed 10-ps 1047 nm quantum laser to produce exact optical replica of ultrafast electron bunches. The replica is generated in apparatus which consists of an input undulator (energy modulator), and the short output undulator (radiator) separated by a dispersion section. The radiation in the output undulator is excited by the electron bunch modulated at the optical wavelength and rapidly reaches 100 MW-level peak power. We then use the now-standard method of ultrashort laser pulse-shape measurement. Fortunately, in the past five years, remarkable progress has occurred in the development of techniques for the measurement of ultrashort laser pulses. For example, a tandem combination of autocorrelator and spectrum (FROG - frequency resolved optical gating) can be used to extract shape information from ultrashort pulses. The FROG trace of ultrashort optical replica can be used to give accurate and rapid electron bunch shape measurements in a way similar to a femtosecond oscilloscope. Real-time single-shot measurements of the electron bunch structure could provide significant information about physical mechanisms responsible for generation ultrashort electron bunches in bunch compressors. The big advantage of proposed technique is that it can be used to determine the slice energy spread and emittance in multishot measurements. It is possible to measure bunch structure completely, that is to measure peak current, energy spread and transverse emittance as a function of time. We illustrate with numerical examples the potential of the proposed method for electron beam diagnostics at the European X-ray FEL. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(04-126) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Design formulas for short-wavelength FELs

Simple formulas for optimization of VUV and X-ray SASE FELs are presented. The FEL gain length and the optimal beta-function are explicitely expressed in terms of the electron beam and undulator parameters. The FEL saturation length is estimated taking into account quantum diffusion in the undulator. Examples of the FEL optimization are given. Parameters of a SASE FEL, operating at the Compton wavelength, are suggested. (orig.)Available from TIB Hannover: RA 2999(04-012) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Calculation of radiative corrections to the cross-section of one-photon annihilation by means of structure functions

Translated from Russian. Published as preprint 84-44 AN SSR, Novosibirsk. Inst. Yadernoj FizikiSIGLEAvailable from Deutsches Elektronen-Synchrotron (DESY), Hamburg (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Longitudinal phase space distortions in magnetic bunch compressors

In this paper we consider a possible mechanism of strong distortions of longitudinal phase space due to collective effects in an electron bunch passing a magnetic bunch compressor. Analytical expressions are derived for the case of a linear compression. The main emphasis is put on analysis of coherent synchrotron radiation (CSR) effects. (orig.)Available from TIB Hannover: RA 2999(01-129) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Introduction to the electroweak theory

SIGLEDEGerman

Scheme for attophysics experiments at a X-ray SASE FEL

We propose a concept for production of high power coherent attosecond pulses in X-ray range. An approach is based on generation of 8th harmonic of radiation in a multistage HGHG FEL (high gain high harmonic free electron laser) configuration starting from shot noise. Single-spike phenomena occurs when electron bunch is passed through the sequence of four relatively short undulators. The first stage is a conventional ''long'' wavelength (0.8 nm) SASE FEL which operates in the high-gain linear regime. The 0.1 nm wavelength range is reached by successive multiplication (0.8 nm #-># 0.4 nm #-># 0.2 nm #-># 0.1 nm) in a stage sequence. Our study shows that the statistical properties of the high-harmonic radiation from the SASE FEL, operating in linear regime, can be used for selection of radiation pulses with a single spike in time domain. The duration of the spikes is in attosecond range. Selection of single-spike high-harmonic pulses is achieved by using a special trigger in data acquisition system. The potential of X-ray SASE FEL at TESLA at DESY for generating attosecond pulses is demonstrated. Since the design of XFEL laboratory at TESLA is based on the use of long SASE undulators with tunable gap, no special place nor additional FEL undulators are required for attophysics experiments. The use of a 10 GW-level attosecond X-ray pulses at X-ray SASE FEL facility will enable us to track process inside atoms for the first time. (orig.)Available from TIB Hannover: RA 2999(02-070) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman