<Emphasis Type="Italic">B</Emphasis>-meson physics: <Emphasis Type="Italic">CP</Emphasis> violation and semileptonic decays

The paper represents a review of our present knowledge on the phenomenology of weak decays of quarks and their role in the determination of the parameters of the Standard Model. Specifically, we focus on CP violation in B decays and the determination of the Cabibbo-Kobayashi-Maskawa matrix element V_cb from exclusive and inclusive semileptonic B decays. We also briefly discuss phenomeno-logical applications concerning the electron energy spectra in inclusive semileptonic B and B_c decays.     

<Emphasis Type="Italic">CP</Emphasis> violation in the 3 jet and 4 jet decays of the <Emphasis Type="Italic">Z</Emphasis> boson at GigaZ

We review CP-violating effects in jet and 4 jet decays, assuming the presence of CP-violating effective and couplings. Longitudinal beam polarization is included in the studies. We propose a direct search for such CP-violating couplings by using various CP-odd observables. The data of a future linear collider running at the Z-resonance in the so-called GigaZ option should give significant information on the couplings. Finally we show that stringent bounds on the mass of excited b quarks can be derived if appropriate couplings are of a size characteristic of a strong interaction.Received: 21 August 2003, Published online: 20 November 2003     

Model-independent analysis of <Emphasis Type="Italic">CP</Emphasis> violation effects in decays of the Higgs boson into a Pair of the <Emphasis Type="Italic">W</Emphasis> and <Emphasis Type="Italic">Z</Emphasis> bosons

Effects of CP and T invariance violation are studied in the most general interaction of the Higgs boson with the intermediate vector W ^± and Z bosons. Various angular distributions of the cascade decay Φ → W ⁺ W ^?/ZZ → 4 of fermions in the transversity and helicity systems are calculated, and asymmetries are constructed and evaluated. It is shown that studying the azimuthal angle distribution of the process Φ → ZZ → (e ^? e ⁺)(μ^?μ⁺) in the transversity system is effective for measuring the spatial parity of the Higgs boson.     

Higgs bosons in the two-doublet model involving <Emphasis Type="Italic">CP</Emphasis> violation

An effective two-doublet Higgs potential that involves complex-valued parameters and whose CP invariance is violated both explicitly and spontaneously is considered. The problem of diagonalizing the mass term of this potential at a local minimum is solved. The eigenstates of Higgs bosons and their mass spectrum are obtained for the special case of the two-doublet Higgs sector of the minimal supersymmetric model, where the CP invariance of the effective potential is violated owing to the interactions of the Higgs fields with the third-generation scalar quarks.     

Majorana neutrinos, <Emphasis Type="Italic">CP</Emphasis> violation,neutrinoless double beta and tritium beta decays

If the present or upcoming searches for neutrinoless double beta ((ββ)_0ν) decay give a positive result, the Majorana nature of massive neutrinos will be established. From the determination of the value of the (ββ)_0ν-decay effective Majorana mass parameter (|〈m〉|), it would be possible to obtain information on the type of neutrino mass spectrum. Assuming 3-ν mixing and massive Majorana neutrinos, we discuss the information that a measurement of, or an upper bound on, |〈m〉| can provide on the value of the lightest neutrino mass m₁. With additional data on the neutrino masses obtained in ³H β-decay experiments, it might be possible to establish whether the CP symmetry is violated in the lepton sector. This would require very high precision measurements. If CP invariance holds, the allowed patterns of the relative CP parities of the massive Majorana neutrinos would be determined.     

<Emphasis Type="Italic">H</Emphasis>/A Higgs mixing in <Emphasis Type="Italic">CP</Emphasis>-noninvariant supersymmetric theories

For large masses, the two heavy neutral Higgs bosons are nearly degenerate in many 2-Higgs doublet models, and particularly in supersymmetric models. In such a scenario the mixing between the states can be very large if the theory is CP-noninvariant. We analyze the formalism describing this configuration, and we point to some interesting experimental consequences.Received: 1 October 2004, Revised: 10 January 2005, Published online: 9 March 2005     

Allowance for <Emphasis Type="Italic">CP</Emphasis> violation in the exponential parametrization of neutrino mixing

An exponential form of the Pontecorvo–Maki–Nakagawa–Sakatamixingmatrix for neutrinos is discussed. This form makes it possible to separate the contributions of purely rotational components of the mixing matrix and elements that are responsible for CP violation. The logarithm of the mixing matrix and exact values for each parameter of the exponential neutrino mixing matrix are found on the basis of the most recent experimental data on neutrino mixing. The parameters of the real rotational part in the exponential representation of the mixing matrix and the parameters of its imaginary part, which is responsible for CP violation, are evaluated. The hypothesis of complementarity of quark and neutrino mixing is confirmed. Factorization in the form of the product of rotations about the real and imaginary axes is demonstrated.     

Light Higgs boson in the two-doublet model featuring explicit <Emphasis Type="Italic">CP</Emphasis> violation

The most general form of an effective two-doublet Higgs potential whose parameters are complex-valued and whose CP invariance is violated explicitly in the minimal supersymmetric model caused by Higgs boson interaction with third-generation squarks is considered. Higgs boson states are obtained and their masses are calculated, along with the decay widths of the lightest Higgs boson and the cross section for its production, in the case of substantial mixing between the CP-even states h and H and the CP-odd state A.     

Radiative <Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> decays revisited

Motivated by recent experimental results and ongoing measurements, we review the chiral perturbation theory prediction for decays. Special emphasis is given to the stability of the inner bremsstrahlung-dominated relative branching ratio versus the K _e3 form factors, and on the separation of the structure-dependent amplitude in differential distributions over the phase space. For the structure-dependent terms, an assessment of the order p ⁶ corrections is given, in particular, a full next-to-leading order calculation of the axial component is performed. The experimental analysis of the photon energy spectrum is discussed, and other potentially useful distributions are introduced.Received: 9 December 2004, Published online: 21 February 2005PACS: 13.20.Eb, 11.30.Rd, 12.39.Fe     

<Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">R</Emphasis>) Cosmology from <Emphasis Type="Italic">q</Emphasis>-theory

From a macroscopic theory of the quantum vacuum in terms of conserved relativistic charges (generically denoted by q ^(a) with label a), we have obtained, in the low-energy limit, a particular type of f(R) model relevant to cosmology. The macroscopic quantum-vacuum theory allows us to distinguish between different phenomenological f(R) models on physical grounds. The text was submitted by the authors in English.     

<Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> decays and CKM unitarity

We present a detailed numerical study of the K_e3 decays to in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |V_us| from the experimental K_e3 decay parameters. We propose a consistency check of the K ⁺ _e3 and K⁰_e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of . Our analysis is highly relevant in view of the recent high statistics measurement of the K ⁺ _e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K⁰_e3 data.Received: 22 January 2004, Published online: 30 April 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain)     

Non-vacuum Bianchi types <Emphasis Type="Italic">I</Emphasis> and <Emphasis Type="Italic">V</Emphasis> in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>) gravity

In a recent paper (Sharif and Shamir in Class. Quantum Grav. 26:235020, 2009), we have studied the vacuum solutions of Bianchi types I and V spacetimes in the framework of metric f (R) gravity. Here we extend this work to perfect fluid solutions. For this purpose, we take stiff matter to find energy density and pressure of the universe. In particular, we find two exact solutions in each case which correspond to two models of the universe. The first solution gives a singular model while the second solution provides a non-singular model. The physical behavior of these models has been discussed using some physical quantities. Also, the function of the Ricci scalar is evaluated.     

The isospin-symmetry-breaking effects in <Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>4</Subscript> decays

The final-state interaction of pions in K _e4 decay allows to obtain the value of the isospin and angular-momentum-zero ππ scattering length a ₀⁰.We take into account the electromagnetic interaction of pions and isospin-symmetry-breaking effects caused by different masses of neutral and charged pions and estimate the impact of these effects on the procedure of scattering-length extraction from K _e4 decays.     

Effects of <Emphasis Type="Italic">C</Emphasis>-, <Emphasis Type="Italic">P</Emphasis>-, <Emphasis Type="Italic">T</Emphasis>-symmetries violation in the polarized elastic electron-proton electroweak scattering

Analytical expressions are obtained for the angular distributions and spin asymmetries of the processes of elastic electromagnetic and electroweak scattering of high energy electrons on polarized/unpolarized proton target with account of C-, P- and T/CP-invariance violating anapole and electric dipole moments, as well as neutral weak electric, magnetic and axial form factors of the proton. Behavior of the P- and T- odd spin asymmetries is studied in dependence of the electron’s energy and scattering angle and proton form factors parameters.     

Polarization effects in rare <Emphasis Type="Italic">K</Emphasis> decays

We review some aspects of rare kaon decays with the polarization of outgoing muons that allows one to study a number of interesting CP-odd or T-odd observables.     

<Emphasis Type="Italic">B</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> meson rare decays in the light-cone quark model

We investigate the rare decays \(B_{c} \rightarrow D_{s}(1968)\ell \overline{\ell}\) and \(B_{c}\rightarrow D_{s}^{*}(2317) \ell \overline{\ell}\) in the framework of the light-cone quark model (LCQM). The transition form factors are calculated in the space-like region and then analytically continued to the time-like region via exponential parametrization. The branching ratios and longitudinal lepton polarization asymmetries (LPAs) for the two decays are given and compared with each other. The results are helpful for investigating the structure of B _c meson and for testing the unitarity of CKM quark mixing matrix. All these results can be tested in the future experiments at the LHC.     

Ferromagnetism and ferroelectricity in Eu<Emphasis Type="Italic">X</Emphasis> (<Emphasis Type="Italic">X</Emphasis> = <Emphasis Type="Italic">O</Emphasis>, <Emphasis Type="Italic">S</Emphasis>): pressure effects

Ferromagnetism and ferroelectricity in Eu monochalcogenides have been investigated by ab initio density functional theory in the DFT+U approach. Exchange interaction parameters and Curie temperatures under pressure are studied and discussed using Heisenberg Hamiltonian with first and second-nearest-neighbor interactions. The calculations showed that the hydrostatic pressure perfectly improves the Curie temperature (EuO: T _C = 175 K; EuS: T _C = 33.8 K) and in the other hand it cannot induce the spontaneous polarization (P _s ). The effect of uniaxial and biaxial pressure is also studied. Although the uniaxial strains slightly increases the Curie temperature, it ensures the ferrolectricity in these systems by producing a spontaneous polarization of the order of P _s (EuO) = 57.50 μC/cm² and P _s (EuS) = 42.86 μC/cm² with pressures of 5% and 4%, respectively. The search for new model systems is a necessity to better understand the physics related to multiferroïc materials and to consider possible applications.