Related papers: The ttbar Threshold and Machine Parameters at the …
Beamstrahlung is a dominant effect in the beam dynamics of the high luminosity next-generation lepton collider FCC-ee. We characterize the beamstrahlung radiation for the beam parameters at the four working energies, from the Z-pole to the…
We discuss diphoton semi(exclusive) production in ultraperipheral $PbPb$ collisions at energy of $\sqrt{s_{NN}}=$ 5.5 TeV (LHC). The nuclear calculations are based on equivalent photon approximation in the impact parameter space. The cross…
Drees and Godbole have proposed that, at the interaction point of an e+e- linear collider, one expects a high rate of hadron production by gamma-gamma collisions, providing an additional background to studies in e+e- annihilation. Using a…
Top quark production in the process $e^+e^- \to t\bar{t}$ at a future linear electron positron collider with polarised beams is a powerful tool to determine indirectly the scale of new physics. The presented study, based on a detailed…
In a class of theories, dark matter is explained by postulating the existence of a `dark sector', which interacts gravitationally with ordinary matter. If this dark sector contains a U(1) symmetry, and a corresponding `dark' photon…
We discuss possibility to detect spin 0, 1 and 1/2 dark matter (DM) at future $e^{+} e^{-}$ colliders. The models considered here are simple, consistent and renormalizable field theories, that provide correct DM abundance and satisfy direct…
We examine the colour structure and charged particle yield for both the $t \bar t$ signal and the irreducible background processes contributing to \eebbww\ production close to the \ttb\ threshold. The charged particle multiplicity for the…
Several key observables of the high-precision physics program at future lepton colliders will critically depend on the knowledge of the absolute machine luminosity. The determination of the luminosity relies on the precise knowledge of some…
We investigate the effects of unparticles on Compton scattering, e gamma -> e gamma based on a future e^+e^- linear collider such as the CLIC. For different polarization configurations, we calculate the lower limits of the unparticle energy…
We study how to probe the anomalous CP-violating couplings of top quark with photon, Z and gluon in the ttbar threshold region at future e+e- colliders. These couplings contribute to the difference of the t and tbar polarization vectors…
The total cross section for top quark pair production close to threshold in e+e- annihilation is investigated. Details are given about the calculation at next-to-next-to-leading logarithmic order. The summation of logarithms leads to a…
The experimental potential of e+e- Linear Colliders to explore the properties of supersymmetric particles is reviewed. High precision measurements of masses, spin-parity, gauge quantum numbers, couplings and mixings, production and decay…
Quantum Mechanics places limits on achievable transverse beam spot sizes of particle accelerators. We estimate this limit for a linear collider to be \Delta x > \hbar c f/E\delta_0 where f is the final focal length, E the beam energy, and…
Measurements of top quark production at $e^+e^-$ colliders can provide a leap in precision in our knowledge of top quark properties and open a new window on physics beyond the Standard Model. In this contribution the top quark physics…
At a prospective e+e- Linear Collider (LC) a very precise determination of the top quark mass with an accuracy of $\delta m_t <= 100 MeV$ will be possible. This is to be compared with the envisaged accuracy of $\delta m_t = 1-2 GeV$ at the…
The top-quark threshold cross section at $e^+e^-$ colliders near production threshold is investigated. We study the scale dependence of the cross section for $\sigma(e^+e^- \to ttX$) near $\sqrt{s} \simeq 2m_t$ and discuss the theoretical…
Using the laser backscattering method at future TeV linear colliders one can obtain gamma-gamma and electron-gamma colliding beams (photon colliders) with the energy and luminosity comparable to that in e+e- collisions. Now this option is…
In $e^+ e^-$ collisions, electromagnetic effects caused by large charge density bunches modify the effective acceptance of the luminometer system of the experiments. These effects consequently bias the luminosity measurement from the rate…
In this work we study the effect of R parity breaking couplings on the process e^-e^-->{\tilde e}_L{\tilde e}_R. We find that an e^-e^- linear collider opearting at a center of mass energy of 500 Gev with a luminosity of 50 fb^{-1} will be…
Fragmentation of heavy quarks into heavy-flavoured hadrons receives both perturbative and non-perturbative contributions. We consider perturbative QCD corrections to heavy quark production in $e^+e^-$ collisions to next-to-next-to-leading…