How to measure the Pomeron phase in diffractive dipion photoproduction

The study of charge asymmetry of pions in the high-energy process gamma p -> pi+ pi- p (e p -> e pi+ pi- p) at very small dipion momenta offers a method to measure the phase of the forward hadronic (quasi)elastic amplitude gamma p -> rho p. We estimate potential of such measurements at HERA.Comment: 12 pages, 2 figures; v4: more elaborate parametrizations of dipion spectra implemented, discussion extende

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

CP odd anomalous interactions of Higgs boson in its production at Photon Colliders

We discuss the potentialities of the study of CP-odd interactions of the Higgs boson with photons via its production at gamma-gamma and e-gamma colliders. Our treatment of H-gamma-gamma and H-Z-gamma anomalous interactions includes a set of parameters, whose impact on physical observables has not been considered before. We focus on two reactions - gamma+gamma-->H and e+gamma-->eH - and introduce the polarization and/or azimuthal asymmetries that are particularly sensitive to specific features of anomalies. We discuss the ways of disentangling effects of physically different parameters of anomalies and estimate what magnitude of CP violating phenomena can be seen in these experiments.Comment: 17 pages, 9 figs; some modifications in the results presentation; version to be published in Eur.Phys.J.

Single Leptoquark Production at e+e−e^+e^- and γγ\gamma\gamma Colliders

We consider single production of leptoquarks (LQ's) at $e^+e^-$ and $\gamma\gamma$ colliders, for two values of the centre-of-mass energy, $\sqrt{s}=500$ GeV and 1 TeV. We find that LQ's which couple within the first generation are observable for LQ masses almost up to the kinematic limit, both at $e^+e^-$ and $\gamma\gamma$ colliders, for the LQ coupling strength equal to $\alpha_{em}$. The cross sections for single production of $2^{nd}$- and $3^{rd}$-generation LQ's at $e^+e^-$ colliders are too small to be observable. In $\gamma\gamma$ collisions, on the other hand, $2^{nd}$-generation LQ's with masses much larger than $\sqrt{s}/2$ can be detected. However, $3^{rd}$-generation LQ's can be seen at $\gamma\gamma$ colliders only for masses at most $\sim\sqrt{s}/2$, making their observation more probable via the pair production mechanism.Comment: plain TeX, 14 pages, 6 figures (not included but available on request), some minor changes to the text, one reference added, figures and conclusions unchanged, UdeM-LPN-TH-93-152, McGill-93/2

Semiempirical methods for computing turbulent flows

Two semiempirical theories which provide a basis for determining the turbulent friction and heat exchange near a wall are presented: (1) the Prandtl-Karman theory, and (2) the theory utilizing an equation for the energy of turbulent pulsations. A comparison is made between exact numerical methods and approximate integral methods for computing the turbulent boundary layers in the presence of pressure, blowing, or suction gradients. Using the turbulent flow around a plate as an example, it is shown that, when computing turbulent flows with external turbulence, it is preferable to construct a turbulence model based on the equation for energy of turbulent pulsations

Evolution of Universe to the present inert phase

We assume that current state of the Universe can be described by the Inert Doublet Model, containing two scalar doublets, one of which is responsible for EWSB and masses of particles and the second one having no couplings to fermions and being responsible for dark matter. We consider possible evolutions of the Universe to this state during cooling down of the Universe after inflation. We found that in the past Universe could pass through phase states having no DM candidate. In the evolution via such states in addition to a possible EWSB phase transition (2-nd order) the Universe sustained one 1-st order phase transition or two phase transitions of the 2-nd order.Comment: 19 pages, 3 figure

Current in narrow channels of anisotropic superconductors

We argue that in channels cut out of anisotropic single crystal superconductors and narrow on the scale of London penetration depth, the persistent current must cause the transverse phase difference provided the current does not point in any of the principal crystal directions. The difference is proportional to the current value and depends on the anisotropy parameter, on the current direction relative to the crystal, and on the transverse channel dimension. An experimental set up to measure the transverse phase is proposed.Comment: 3 pages, 1 figur

Field-dependent diamagnetic transition in magnetic superconductor Sm1.85Ce0.15CuO4−ySm_{1.85} Ce_{0.15} Cu O_{4-y}

The magnetic penetration depth of single crystal $\rm{Sm_{1.85}Ce_{0.15}CuO_{4-y}}$ was measured down to 0.4 K in dc fields up to 7 kOe. For insulating $\rm{Sm_2CuO_4}$, Sm$^{3+}$ spins order at the N\'{e}el temperature, $T_N = 6$ K, independent of the applied field. Superconducting $\rm{Sm_{1.85}Ce_{0.15}CuO_{4-y}}$ ($T_c \approx 23$ K) shows a sharp increase in diamagnetic screening below $T^{\ast}(H)$ which varied from 4.0 K ($H = 0$) to 0.5 K ($H =$ 7 kOe) for a field along the c-axis. If the field was aligned parallel to the conducting planes, $T^{\ast}$ remained unchanged. The unusual field dependence of $T^{\ast}$ indicates a spin freezing transition that dramatically increases the superfluid density.Comment: 4 pages, RevTex

The evolution of vacuum states and phase transitions in 2HDM during cooling of Universe

We consider the evolution of the ground state in the Two Higgs Doublet Model during cooling down of the Universe after the Big Bang. Different regions in the space of free parameters of this model correspond to different sequences of thermal phase transitions. We discuss different paths of thermal evolution and corresponding evolution of physical properties of the system for different modern values of the parameters.Comment: 28 pages, 12 figure