arXiv subjects
Publications and source records attributed to A. A. Likhoded.
The calculation of the transverse muon polarization in $K^+ \to μ^+ νγ$ decay due to the final state interaction up to $O(p^6)$ CHPT level has been carried out. It is shown that $O(p^6)$ corrections to the observable is much less than $O(p^4)$ contribution.
The dependence of the T-odd correlation on the effective Lagrangian parameters in the $K^+ \to πl νγ, l=e, μ$ decays is analyzed. It is shown that the introduced observable is perspective in a search for new physics in the vector and pseudovector sector of the Lagrangian. As for scalar and pseudoscalar sectors, the T-odd correlation studies will not allow one to improve current restrictions on parameters of models beyond SM.
The effect of lepton transverse polarization in the B^0 --> D^- l^+ nu_l, B^+ --> bar(D^0) l^+ nu_l decays (l= tau, mu) is analyzed within the framework of Standard Model in the leading order of HQET. It is shown that the non-zero transverse polarization appears due to the electromagnetic final state interaction. The diagrams with intermediate D, D^* - mesons contributing to the non-vanishing P_T are considered. Regarding only the contribution of these mesons, values of the tau-lepton transverse polarization, averaged over the physical region, in the B^0 --> D^- tau^+ nu_l and B^+ --> bar(D^0) tau^+ nu_l decays are equal to $2.60 cdot 10^{-3} and -1.59 cdot 10^{-3}, correspondingly. In the case of muon decay modes the values of are equal to 2.97 cdot 10^{-4} and -6.79 cdot 10^{-4}.
The muon transverse polarization in the $K^+ \to μ^+ νγ$ process induced by the electromagnetic final state interaction is calculated in the framework of Standard Model. It is shown that one loop contributions lead to a nonvanihing muon transverse polarization. The value of the muon transverse polarization averaged over the kinematical region of $E_γ\geq 20$ MeV is equal to $5.63 \times 10^{-4}$.
We consider two possible sources of the $T$-violating muon transverse polarization in the process $K^+ \to μ^+ νγ$: electromagnetic final state interaction in the SM and contribution due to charged-Higgs exchange diagrams in the framework of the Weinberg three doublets model. It is shown that at the one-loop level of the SM the muon transverse polarization, $P_T^{SM}$, varies within $(0.0 ÷1.1 \cdot 10^{-3})$ in the Dalitz plot region. Averaged value of the muon polarization, $ $, in the kinematic region of $E_γ\geq 20$ MeV is equal to $4.76\cdot 10^{-4}$. In the case of the model with three Higgs doublets the muon transverse polarization is calculated as a function of charged Higgs masses, imaginary part of the Yukawa coupling constants product and vacuum expectation values of the Higgs doublets. The averaged value of the transverse polarization in the Weinberg model is $ = - 6.62 \cdot 10^{-5}$. Perspectives to probe the effect caused by the charged Higgs exchange diagrams in planned kaon experiments are discussed.
The dependence of the $K^+ \to π^0 l^+ ν_l γ$ decay width on the $T$-odd kinematical variable, $ ξ= {\vec q \cdot [\vec p_l \times \vec p_π]} / {M^3}$, is studied at the tree and one-loop levels of Standard Model. It is shown that at the tree level this decay width is the even function of $ξ$, while the odd contribution arises due to the electromagnetic final state interaction. This contribution is determined by imaginary parts of one-loop diagrams. The calculations performed show that the $ξ$-odd contribution to the $K^+ \to π^0 e^+ ν_e γ$ and $K^+ \to π^0 μ^+ ν_μγ$ decay widths is four orders of magnitude smaller than even contribution coming from the tree level of SM.
We study the sensitivity of a 500 GeV $e^+e^-$ Linear Collider to $CP$ violating anomalous couplings. We find that with 50~fb$^{-1}$, and taking only one non-zero coupling at a time, the process $e^+e^-\to W^+ W^-$ can be used to place the 95% confidence level bounds $|\tildeκ_γ|\leq0.1$, $|\tildeκ_Z|\leq 0.1$ and $|g_4^Z|\leq 0.1$ from CP even observables. By studying certain distributions in the process $e^+e^-\to μ^+μ^-ν\barν$ one of the bounds can be improved to $|g_4^Z| \leq 0.06$. This process also allows the construction of a CP odd observable which can be used to place bounds on CP violating new physics. At the 95% confidence level we find $|\tildeκ_γ|\leq 0.3$, $|\tildeκ_Z|\leq 0.2$ and a much weaker bound for $|g_4^Z|$.
We consider the possibility of observing deviations from the Standard Model gauge-boson self-couplings at a future $500$~GeV $e^+ e^-$ linear collider. We concentrate on the case in which the electroweak symmetry breaking sector is strongly interacting and there are no new resonances within reach of the collider. We find a sensitivity to the anomalous couplings that is two orders of magnitude higher than that achievable at LEP II. We also show how a polarized electron beam extends the reach of the collider, allowing experiments to probe different directions in parameter space.
We study the potential of the next-generation $e^+ e^-$ linear colliders with longitudinally polarized beams, to restrict the values of the anomalous trilinear couplings $WWγ$ and $WWZ$ from the measurement of the process $e^+ e^-\to W^+ W^-$. Along with initial $e^+e^-$ polarization, we account also for the possibilities offered by cross sections for polarized final $W$, in order to disentangle the constraints on the various constants. The results show the essential role of the initial beams polarization in improving the bounds obtained from the unpolarized case.