Spontaneous CP violation in extended technicolor models with horizontal U(2)L ⊗ U(2)R flavor symmetries (I)

The Eichten, Lane, Preskill mechanism for CP violation in extended technicolor (ETC) models is examined in models with “horizontal” U(2)_L ? U(2)_R flavor symmetries. We identify a class of chiral perturbations which generate spontaneous CP violation when the vacuum alignment is determined by Dashen's theorem, and show that, in general, a discrete symmetry must be invoked to avoid strong CP non-conservation. CP-violating phases appearing in the electroweak and broken ETC interactions may be naturally suppressed by ratios of ETC vector boson masses.     

Vacuum alignment by broken gauge interactions

We study the problem of vacuum alignment by the extended technicolour (ETC)forces which have been invoked to give mass to ordinary fermions (quarks and leptons) in technicolour theories. We find that the ETC interactions prefer to align the vacuum in such a way as to give the maximum possible mass to the ordinary fermions. We show that the P⁰, P³, P^+-, P₈⁰, P₈³, and P₈^+- pseudo-Goldstone bosons in one technifamily ETC models cannot acquire any mass from ETC interactions alone. Finally, we point out that the Pati-Salam unification which has been invoked to give mass to the P⁰ and P³ implies a remaining discrete degeneracy of the vacuum.     

On pseudo-Goldstone boson masses from broken gauge interactions

We investigate the effects of extended technicolour interactions on the masses of pseudo-Goldstone bosons in one-technifamily models. We find that the P⁰ and P³ cannot acquire any masses from ETC, while the P^± only acquire contributions of order g_Wg_ETC (?5 GeV). This removes a major source of uncertainty in the masses of these particles.     

Predictions of the CKM model for CP asymmetries in B decay

We discuss present-day uncertainties for the value of the CP-violating phase δ in the CKM matrix and point out how a knowledge of m_t and/or x_s could substantially reduce this uncertainty. A model-independent measurement of δ is, in principle, possible by studying certain CP-violating asymmetries, involving B⁰ mesons decaying into CP-conjugate hadronic final states. There exist three different classes of these asymmetries and we give estimates for their values, based on our present knowledge of the CKM matrix. Some comments on the experimental requirements for detecting these asymmetries are also presented.     

Search for light technimesons

The light neutral colour-singlet spin-zero bosons P⁰ and P³ expected in contemporary extended technicolour theories have some small induced flavour-changing couplings, even in monophagic theories where their couplings are mainly flavour-diagonal. Their non-observation in K⁺ decay means that $\text{m}{}_{\mathrm{<mtext>P</mtext>}}\text{0,3 ? 350}\text{MeV}$, leading one to expect direct quark-lepton transitions mediating K_L0 → μe decay close to the present experimental upper limit. In the absence of some as yet unknown suppression mechanisms, eitherP⁰ and P³ should be observed in bottom decays with a branching ratio approaching 100% (which may already be experimentally excluded) and/or they should be observed in charm decays with branching ratios ? 1% and/or the decay K⁰_L → μe should be detected within an order of magnitude of the present upper limit.     

CP violation andZ boson decays

We present a general discussion ofCP-violating effects in the following two and three body decays of theZ boson:Z→l ⁺ l ^?,Z→l ⁺ l ^?γ, wherel=e, μ, τ andZ→2 jets,Z→ 2 jets+γ, andZ→ 3 jets. Experimental observables sensitive toCP violation in these decays are discussed systematically for the case that polarizations of final state particles are not observed. It is shown that the standard model predicts only extremely smallCP-violating effects for the above decays. PossibleCP-violating interactions beyond the standard model are parametrized in terms of aCP-odd effective Lagrangian containing coupling constants proportional to Λ _P ^-1 and Λ _P ^-2 . Here Λ _CP is the mass scale associated with the assumed new interactions. We give estimates of the bounds obtainable for Λ _CP in experiments at LEP1.     

πℓ2, Kℓ3and K0−K0 constraints on leptoquarks and supersymmetric particles

Mass bounds from different processes for charged Higgs particles, for pseudoscalar leptoquarks occurring in dynamically broken theories, for vector leptoquarks occurring in the Pati-Salam type of grand unified theories and for the exotic particles of supersymmetric theories are studied. The processes considered are the π → eν to π → μν branching ratio, the CP-violating K?3 decay parameters, and the CP-violating part of the K_L ? K_S mass difference. The π → eν to π → μν branching ratio sets the most stringent bounds, 0.5 TeV for charged Higgs particles, 1 TeV for pseudoscalar leptoquarks, 125 TeV for vector leptoquarks and 0.1–1 TeV for the supersymmetric partners of ordinary particles. The π?2 branching ratio should be sensitive at the present experimental accuracy to the effects of pseudoscalar leptoquarks.     

Probing ZWW couplings through Z0→Wff′

We investigated the possibility of probing the ZWW couplings through the rare decay mode Z⁰→Wff′ of Z⁰. Neglecting masses of the fermions, we computed the combined polarization density matrix of Z and W as a function of the most general ZWW couplings. Integrations over phase space are carried out and the diagonal matrix elements are expressed as quadratic forms of the seven independent couplings. We found that several charge symmetrix polarization channels are particularly sensitive to the CP-violating coupling f₆, which is proportional to the weak magnetic quadrupole moment.     

Visions: The coming revolutions in particle physics

We study the branching ratio, CP-violating asymmetry, forward-backward asymmetry and the CP-violating asymmetry in the forward-backward asymmetry for the exclusive decay B → Kτ⁺τ⁻ in the two Higgs doublet model with tree level flavor changing neutral currents (model III). We analyse the dependencies of these quantities on the neutral Higgs boson contributions and the CP parameter sinθ in the model III. We observe that to determine the neutral Higgs boson effects, the measurements of the forward-backward asymmetry and the CP-violating asymmetry in the forward-backward asymmetry for the decay B → Kτ⁺τ⁻ are promising.     

Electric dipole moments as probes of new physics

We review several aspects of flavour-diagonal CP-violation, focussing on the role played by the electric dipole moments (EDMs) of leptons, nucleons, atoms, and molecules, which constitute the source of several stringent constraints on new CP-violating physics. We dwell specifically on the calculational aspects of applying the hadronic EDM constraints, reviewing in detail the application of QCD sum-rules to the calculation of nucleon EDMs and CP-odd pion-nucleon couplings. We also consider the current status of EDMs in the Standard Model, and on the ensuing constraints on the underlying sources of CP-violation in physics beyond the Standard Model, focussing on weak-scale supersymmetry.     

Heavy fourth-generation neutrino and flavour-changing neutral currents

We study the flavour-changing neutral currents in the case that the fourth-generation neutrino exists and the known three left-handed neutrino masses are at the experimental limits of the direct measurements. The fourth-generation neutrino has the mass of order a few ten GeV and the flavour-changing processes of the heavy neutrinos are expected to be observed onZ ⁰ ine ⁺ e ^? collisions. The heavy fourth-generation neutrino is significant to reveal the nature of the neutrino; Dirac or Majorana, the see-saw mechanism and the right-handed scale.     

R-parity violation and unification

The reported anomaly in deep-inelastic scattering at HERA has revived interest in the phenomenology of R-parity violation. From the theoretical point of view, the existence of R-violating interactions poses two considerable problems. The first one concerns the flavour structure of the interactions and the origin of an appropriate suppression of flavour-changing neutral-current processes and lepton-family transitions. The second one concerns the way of embedding R-violating interactions in a grand unified theory (GUT) without introducing unacceptable nucleon decay rates. We show that the second problem can be solved by mechanism which is purely group theoretical and does not rely on details of the flavour theory. We construct explicit GUT models in which our mechanism can be realized.     

Radiated energy loss due to beamstrahlung in high-energy electron-positron linear colliders

We studyT-odd andCP-odd triple momentum correlations in exclusive semi-leptonic charm meson decaysDK ^*(K)lv _l . We define asymmetry ratios that measure the trueCP-violating effects, andT-odd triple momentum correlation effects from unitarity contributions. Possible newCP-violating contributions are parametrized in terms of an effective four-fermion Hamiltonian whereCP-violating effects should come from new non-standard sources. A detailed analysis of the left-right model and the Weinberg Higgs-boson model ofCP-violation is carried out.Supported by Bundesministerium für Forschung und Technologie (BMFT), FRG     

Compatibility of the K+n and K−n total cross section measurements,KL0-KS0 regeneration amplitude on hydrogen and CP-violating parameter |η+−|

It is shown that the K⁺n- and K^?n total cross section differenceis and the K_L⁰-K_S⁰ transmission regeneration amplitude measurements at high energies are in good agreement with the CP-violating parameter value |ν_+? = (2.30±0.03) × 10^?3.     

Radiative Kaon decays and CP violation in chiral perturbation theory

Chiral perturbation theory is a very useful framework for testing the standard model in processes where long-distance effects are expected to play an essential rôle. We analyze the rare K decays K⁰→γℓ⁺ℓ⁻, K⁺→π⁺γ3 and K_L→π⁰ℓ⁺ℓ⁻ in the effective chiral formulation of the standard model. These processes, like the decays K⁰→γγ, K⁺→π⁺ℓ⁺ℓ⁻, K_S→π⁰ℓ⁺ℓ⁻ and K⁰→π⁰γγ discussed in previous work, have the property that the corresponding amplitudes vanish to lowest order in chiral perturbation theory. Precise predictions for decay rates and spectra are made in terms of a few coupling constants not restricted by softly broken chiral symmetry alone. Special consideration is given to various possible tests of CP noninvariance in these decays, in particular to effects due to intrinsic CP violation in the amplitudes. We find that chiral perturbation theory correlates different CP-violating observables such as the charge asymmetries in K^±→π^±γγ and K^±→π^±ℓ⁺ℓ⁻, the one-photon exchange contribution to K_L→π⁰e⁺e⁻ and the transverse polarization in K_L →π⁰μ⁺μ⁻. Detailed numerical results are shown.     

CP violation with beautiful baryons

CP violation can be studied in modes of charmed or bottom baryons when a decay process is compared with its charge-conjugated partner. It can show up as a rate asymmetry and in a study of other decay parameters. Neither tagging nor time-dependences are required to observeCP violation with modes of baryons, in contrast to the conventionalB ⁰ modes. Numerous modes of bottom baryons have the potential to show largeCP-violating effects within the Standard Model. Those effects can be substantial for modes with aD ⁰, which is seen in a final state that can also be fed from a \(\bar D^0 \) . For instance, a comparison of theΛ _b→Λ _CP ⁰ with the \(\bar \Lambda _b \to \bar \Lambda D_{CP}^0 \) process can show sizeableCP violation. HereD _CP ^o denotesCP eigenstates ofD ⁰, which occur at a few percent. Six related processes, such asΛ _b→ΛD ⁰, \(\Lambda _b \to \Lambda \bar D^0 \) ,Λ _b→Λ _CP ⁰ , and their charge-conjugated counterparts, can extract ?, which is the most problematic angle of the unitarity triangle and which is conventionally probed with theB _s→ρ⁰ K _S asymmetry. HereD ⁰ andD ^?0 are identified by their charged kaon or lepton. We predictB(Λ _b→ΛD ⁰)～10^?5, thusB(Λ _b→Λ _CP ⁰ )～10^?7. Under favourable circumstances,CP violation can occur at the few tens of percent level. Thus 10²–10³ Λ _b→Λ _CP ⁰ decays start probing ?. Tables list many additional modes with typical branching ratios at the 10^?5–10^?6 level, with large detection efficiencies (in contrast to theD _CP ⁰ ), and with potentially largeCP-violating effects, such as Ξ _b ⁰ →ΛΨ, Λ?, ΛK^*0; Ξ _b ^? →ΛK^(*)?, Ξ^?K_s, Ξ^?K^*0, Ω _b ^? →Ξ^?φ, Ξ^?ρ⁰, ΛK^(*)?, ΩK_s, Ω^?K^*0.     

Searching for signatures of supersymmetry at B-factories

We analyze the predictions for CP asymmetries in B⁰-meson decays within the framework of the supersymmetric standard model (SSM). It is pointed out that owing to sizable new contributions to B_d⁰−B⁰_d and K⁰−K⁰ mixings, the experimentally allowed range for the CP-violating phase δ of the Cabibbo-Kobayashi-Maskawa matrix may be different from the one obtained in the standard model (SM). This has important effects on the allowed values of CP asymmetries in B⁰-meson decays and on their correlations. We calculate the ratio R of the SSM and the SM contributions to the B⁰d–B⁰_d mixing parameter x_d and discuss in detail the ranges of R and S which are consistent with the experimental values of x_d and the CP violation parameter ϵ for K⁰–K⁰ mixing. The CP asymmetries are predicted to have values different from the SM_predictions in sizable regions of parameter space. We also discuss the SSM predictions for B⁰_s–B⁰_s mixing.     

Mixing angles,mass matrix and CP violation in the Kobayashi-Maskawa model

We analyze the K_L ? K_S mass difference Δm and CP-violating parameters η_+? and η₀₀ in terms of the mixing angles of the six-quark Kobayashi-Maskawa model. In contrast to previous analyses, we include a parameter to allow for uncalculable contributions of low-mass intermediate states to the mass matrix. As a result, Δm provides only weak constraints on the mixing angles but stronger constraints may possibly be obtained using data on η₀₀.     

Lepton hadron angular correlations in semileptonic ∋ decays

We studyT-odd triple momentum correlations in exclusive semileptonic -decays into three pseudoscalar mesons. We define asymmetry ratios that measure theseT-odd correlations and show how to separate the unitarity contribution from the trueCP-violating contributions. TheCP-violating contributions to the asymmetry ratios would have to come from new non-Standard Model sources as theCP-violating Standard Model contributions to the asymmetry ratios are zero. We discuss two extensions of the Standard Model that give rise to nonvanishingCP-violating triple momentum correlations, namely a left-right symmetric model and a multi Higgs boson model. Numerical results on triple momentum correlations are given for the three-pseudoscalar meson final statesK ^{- - +} andK ^{- -} K ⁺.Supported by Cusanuswerk