e+e−→H+H−e^+e^-\to H^+H^- signals at LEP2 energies in the Minimal Supersymmetric Standard Model

In this paper we compare $H^+H^-$ and $W^+W^-$ into four-fermion production at centre-of-mass energies typical of LEP2 and somewhat larger. The theoretical framework considered is the Minimal Supersymmetric Standard Model. The interest in exploiting the $e^+e^-$ CERN collider at values of $\sqrt s$ greater than 192 GeV could come from the discovery of Supersymmetric signals during runs at lower energy. If these indicate that a charged Higgs boson exists in the mass range \MH\approx95-105 GeV, then a few years of running at $\sqrt s=205-215$ GeV and nominal luminosity could make the detection of such scalars feasible, in the purely leptonic channel $\tau\nu_\tau\tau\nu_\tau$ and, for small \tb's, also in the semi-hadronic(leptonic) one ${jj}\tau\nu_\tau$. Charged Higgs bosons of the above nature cannot be produced by the beam energies approved at present for LEP2. However, if runs beyond the so-called `192 GeV cryogenic limit' will be approved by the CERN Council, our selection procedure will enable us to establish the presence, or otherwise, of charged Higgs bosons in the mentioned mass rangeComment: 30 pages, latex, epsfig, 12 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9615 and at http://www.hep.phy.cam.ac.uk/theory/papers

The flavor-changing bottom-strange quark production in the littlest Higgs model with T parity at the ILC

In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the special flavor structures and some new flavor-changing (FC) couplings which could greatly enhance the production rates of the FC processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider (ILC), i.e., $e^+e^-\rightarrow b\bar{s}$ and $\gamma\gamma\rightarrow b\bar{s}$. The results show that the production rates of these processes are sizeable for the favorable values of the parameters. Therefore, it is quite possible to test the LHT model or make some constrains on the relevant parameters of the LHT through the detection of these processes at the ILC.Comment: 12 pages, 8 figure