Charmless Hadronic Decays B→VV in the Topcolor－Assisted Technicolor Model

Based on the effective Hamiltonian with the generalized factorization approach, we calculate the branching ratios and CP asymmetries of B→VV decays in the Topcolor-assisted Technicolor (TC2) model. Within the considered parameter space we find that: (a) for the penguin-dominated B→K^*+φ and K^*0φ decays, the new physics enhancements to the branching ratios are around 40%; (b) the measured branching ratios of B→K^*+φ and K^*0φ decays prefer the range of 3≤N_c^eff≤5; (c) the SM and TC2 model predictions for the branching ratio B(B⁺→ρ⁺ρ⁰) are only about half of the Belle's measurement; and (d) for most B→VV decays, the new physics corrections on their CP asymmetries are generally small or moderate in magnitude and insensitive to the variation of m_π and N_c^eff.     

Charmless hadronic decays of B mesons to a pseudoscalar and a tensor meson

We study two-body charmless hadronic decays of B mesons to a pseudoscalar meson (P) and a tensor meson (T) in the frameworks of both flavor SU(3) symmetry and generalized factorization. Certain ways to test the validity of the generalized factorization are proposed, based on the flavor SU(3) analysis. We present a set of relations between a flavor SU(3) amplitude and the corresponding amplitude in the generalized factorization which bridge both approaches in decays. The branching ratios and CP asymmetries are calculated using the full effective Hamiltonian including all the penguin operators and the form factors obtained in the non-relativistic quark model of Isgur, Scora, Grinstein and Wise. We identify the decay modes in which the branching ratios and CP asymmetries are expected to be relatively large. Received: 6 July 2001 / Revised version: 8 October 2001 / Published online: 30 November 2001     

General analysis of CP-violation in polarized $b \rightarrow d \ell^ + \ell^-$ decay

The CP-violating asymmetries in the decay, when one of the leptons is polarized, is investigated using the most general form of the effective Hamiltonian. The sensitivity of the CP-violating asymmetries to the new Wilson coefficients is studied.Received: 23 August 2003, Published online: 4 November 2003     

S pin a symmetrie s in ela stic electroweak ν($$ \bar v $$) p( s) scattering with allowance for the neutral weak magnetic,ana pole,and electric di pole moment s of the proton

Analytic expressions for cross sections and spin asymmetries characterizing processes of elastic weak, electromagnetic, and electroweak scattering of a neutrino (antineutrino) having electromagnetic moments on a polarized or an unpolarized proton target were obtained with allowance for the C-, P-, and T/CP-violating anapole and electric dipole moments and the neutral weak, electric, magnetic, and axial form factors of the proton, and these expressions were analyzed. The behavior of spin asymmetries was studied versus the energy and form-factor parameters.     

A general analysis of \gamma determinations from B\to\pi K decays

We present a general parametrization of , and , decays, taking into account both electroweak penguin and rescattering effects. This formalism allows – among other things – a generalized implementation of the strategies that were recently proposed by Neubert and Rosner to probe the CKM angle with the help of , decays. In particular, it allows us to investigate the sensitivity of the extracted value of to the basic assumptions of their approach. We find that certain rescattering processes may have an important impact and emphasize that additional hadronic uncertainties may be due to non-factorizable SU(3)-breaking effects. The former can be controlled by using SU(3) flavour symmetry arguments and additional experimental information provided by modes. We propose a new strategy to probe the angle with the help of the neutral decays , , which is theoretically cleaner than the , approach. Here rescattering processes can be taken into account by just measuring the CP-violating observables of the decay . Finally, we point out that an experimental analysis of modes would also be very useful to probe the CKM angle , as well as electroweak penguins, and we critically compare the virtues and weaknesses of the various approaches discussed in this paper. As a by-product, we point out a strategy to include the electroweak penguins in the determination of the CKM angle from decays. Received: 14 June 1999 / Published online: 28 September 1999     

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.     

Effect of fourth generation CP phase on $b\to s$ transitions

We study the effect of a sequential fourth generation on , B_s mixing, , and , taking into account the presence of a new CP phase in quark mixing. We find that the effects via electromagnetic and strong penguins, such as in or CP-violation in , are rather mild, but the impact via boxes or Z penguins is quite significant. Not only can one have a B_s mixing much larger than expected, even if it is measured near the present limit, mixing-dependent CP-violation could become maximal. For electroweak penguin modes, the fourth generation can provide the enhancement that perhaps may be needed, while the dependence of the forward-backward asymmetry in can further probe for the fourth generation. These effects can be studied in detail at the B factories and the Tevatron. Received: 20 November 2002 / Published online: 7 March 2003     

The radiative leptonic decays D^0 \to e^+ e^-\gamma,\mu^+\mu^-\gamma in the standard model and beyond

We present a calculation of the rare decay modes and in the framework of the standard model. For the short distance part we have derived QCD corrections to the Wilson coefficients involved, including C₉. The latter is found to be strongly suppressed by the corrections, leading to diminished values for the branching ratios in the 10^-10 range. Within SM the exclusive decays are dominated by long distance effects. Non-resonant contributions are estimated using heavy quark and chiral symmetries to be at the level of , compared to the contributions arising from , with . The total SM branching ratio is predicted to be in the range (1-. We also consider contributions coming from MSSM with and without R parity conservation. The effects from MSSM are significant only for the R parity violating case. Such contributions enhance the branching ratio to , based on appropriately allowed values for C₉ and C₁₀. This selects as a possible probe of new physics. Received: 25 October 2002 / Published online: 24 January 2003     

New aspects of B → ππ, πK and their implications for rare decays

We analyze the B → ππ, πK modes in the light of the most recent B-factory data, and obtain the following new results: (i) the modes prefer γ = (74±6)°, which - together with |V_ub/V_cb| - allows us to determine the "true" unitarity triangle and to search for CP-violating new-physics contributions to B⁰_d- mixing; (ii) the B → πK puzzle reflected in particular by the low experimental value of the ratio R_n of the neutral B → πK rates persists and still favors new physics in the electroweak penguin sector with a new CP-violating phase ϕ ~ –90°, although now also ϕ ~ +90° can bring us rather close to the data; (iii) the mixing-induced CP asymmetry is a sensitive probe of the sign of this phase, and would currently favor ϕ ~ +90°, as well as the direct CP asymmetry of , which suffers, however, from large hadronic uncertainties; (iv) we investigate the sensitivity of our B → πK analysis to large non-factorizable SU(3)-breaking effects and find that their impact is surprisingly small so that it is indeed exciting to speculate on new physics; (v) assuming that new physics enters through Z⁰ penguins, we study the interplay between B → πK and rare B, K decays and point out that the most recent B-factory constraints for the latter have interesting implications, bringing us to a few scenarios for the future evolution of the data, where also the mixing-induced CP violation in plays a prominent r?le.     

Supersymmetric Higgs boson decays in the MSSM with explicit <Emphasis Type="Italic">CP</Emphasis> violation

Decays into neutralinos and charginos are among the most accessible supersymmetric decay modes of Higgs particles in most supersymmetric extensions of the standard model. In the presence of explicitly CP violating phases in the soft breaking sector of the theory, the couplings of Higgs bosons to charginos and neutralinos are in general complex. Based on a specific benchmark scenario of CP violation, we analyze the phenomenological impact of explicit CP violation in the minimal supersymmetric standard model on these Higgs boson decays. The presence of CP violating phases could be confirmed either directly through the measurement of a CP odd polarization asymmetry of the produced charginos and neutralinos, or through the dependence of CP even quantities (branching ratios and masses) on these phases. Received: 18 April 2002 / Published online: 26 July 2002     

Electroweak corrections to the fermionic decay width of the standard Higgs boson

The partial decay width of the standard model Higgs particle into a general species of fermions is given at the electroweak 1-loop level. The analytic formulae are applicable to light and heavy fermions. Numerical results are presented for Higgs decays intob andt quarks and into charged leptons. For not too heavy Higgs bosons the radiative corrections are of the order of a few per cent. In particular for Higgs bosons below theW ⁺ W ^– threshold the correction to the partial width intob quarks is very small and insensitive to the top mass. For every heavy Higgs bosons the 1-loop corrections increase the fermionic decay widths for all channels up to 15%.     

Exploring CP violation and penguin effects through B0d→D+D- and B0s→D+sD-s

The decay B⁰ _d→D⁺D^- offers an interesting probe of CP violation, but it requires control of penguin effects, which can be done through B⁰ _s→D⁺ _sD^- _s by means of the U-spin flavour symmetry of strong interactions. Recently, the Belle collaboration reported indications of large CP violation in the B⁰ _d decay, which were, however, not confirmed by BaBar, and first signals of the B⁰ _s channel were observed at the Tevatron. In view of these developments and the quickly approaching start of the LHC, we explore the allowed region in observable space for CP violation in B⁰ _d→D⁺D^-, perform theoretical estimates of the relevant hadronic penguin parameters and observables, and we address questions both about the most promising strategies for the extraction of CP-violating phases and about the interplay with other measurements of CP violation and the search for new physics. As far as the latter aspect is concerned, we point out that the B⁰ _q→D_q ⁺D^- _q system provides a setting for the determination of the B⁰ _q–B̄⁰ _q mixing phases (q∈{d,s}) that is complementary to the conventional B⁰ _d→J/ψK_S and B⁰ _s→J/ψφ modes with respect to possible new-physics effects in the electroweak penguin sector.     

On the role of the final-state interactions in rare <Emphasis Type="Italic">B</Emphasis> decays

The effects of final-state interactions (FSI) in hadronic B decays are investigated. The model for FSI, based on Regge phenomenology of high-energy hadronic interactions, is proposed. It is shown that this model explains the pattern of phases in matrix elements of B → ππ and B → ρρ decays. These phases play an important role for CP violation in B decays. The most precise determination of the unitarity triangle angle α from B _d → ρπ decays is performed. The relation between CP asymmetries in B → Kπ decays is discussed. It is emphasized that the large-distance FSI can explain the structure of polarizations of the vector mesons in B decays and other puzzles like a very large branching ratio of the B decay to $ \bar \Xi $ \bar \Xi _c Λ _c .     

B meson decays to baryons in the diquark model

We study B meson decays to two charmless baryons in the diquark model, including strong and electroweak penguins as well as the tree operators. It is shown that penguin operators can enhance considerably, but affect only slightly, where and are non-strange and strange baryons, respectively. The dependence of the decay rates due to tree–penguin interference is illustrated. In principle, some of the modes could dominate over for , but in general the effect is milder than their mesonic counterparts. This is because the operator can only produce vector but not scalar diquarks, while the opposite is true for and . Predictions from the diquark model are compared to those from the sum rule calculation. The decays and inclusive baryonic decays are also discussed. Received: 27 December 2001 / Published online: 5 April 2002     

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.     

Extracting rephase-invariant <Emphasis Type="Italic">CP</Emphasis> and <Emphasis Type="Italic">CPT</Emphasis> violating parameters from asymmetries of time-ordered integrated rates of correlated decays of entangled mesons

We present a general model-independent formalism of measuring CP and CPT violating parameters through time-ordered integrated rates of correlated decays of C=±1 entangled states of neutral pseudoscalar mesons. We give the general formulae of CP and CPT violating parameters in terms of four measurable asymmetries defined for the time-ordered integrated rates, applicable to all kinds of decay product. Two special cases which are often realized in experiments are discussed specifically.     

Puzzles in B physics

I discuss some puzzles observed in exclusive B-meson decays, concentrating on the large difference between the direct CP asymmetries in the B ⁰ → π⁻ K ⁼ and B ^± → π⁰ K ^± modes, the large B ⁰ → π⁰π⁰ branching ratio, and the large deviation of the mixing-induced CP asymmetries in the b → sqq penguins from those in the b → ccs trees.     

The rare K decays and Z^0 penguin contributions in the topcolor-assisted technicolor models

We calculate the new contributions to the rare decays K, and from new Z penguin and box diagrams induced by the unit-charged scalars appearing in the topcolor-assisted technicolor (TC2) models. We find that: (a) the unit-charged top-pion and b-pion can provide large contributions to the rare K decays if they are relatively light; (b) the size of the mixing elements () is strongly constrained by the data of B meson mixing: for and GeV; (c) the enhancements to the branching ratios of rare K decays from new scalars can be as large as one order of magnitude; (d) there is a strong cancellation between the short- and the long-distance dispersive part of the decay , the constraint on the new short-distance part from this decay mode is thus not strong; (e) the typical TC2 model under study is generally consistent with the available rare K-decay data. Received: 24 November 1998 / Revised version: 16 February 1999 / Published online: 15 July 1999     

Two-body decays of gluino at full one-loop level in the quark-flavour violating MSSM

We study the two-body decays of the gluino at full one-loop level in the Minimal Supersymmetric Standard Model with quark-flavour violation (QFV) in the squark sector. The renormalisation is done in the \(\overline{\mathrm{DR}}\) scheme. The gluon and photon radiations are included by adding the corresponding three-body decay widths. We discuss the dependence of the gluino decay widths on the QFV parameters. The main dependence stems from the \(\tilde{c}_R \)–\( \tilde{t}_R\) mixing in the decays to up-type squarks, and from the \(\tilde{s}_R \)–\( \tilde{b}_R\) mixing in the decays to down-type squarks due to the strong constraints from B-physics on the other quark-flavour-mixing parameters. The full one-loop corrections to the gluino decay widths are mostly negative and of the order of about ?10%. The QFV part stays small in the total width but can vary up to ?8% for the decay width into the lightest \(\tilde{u}\) squark. For the corresponding branching ratio the effect is somehow washed out by at least a factor of two. The electroweak corrections can be as large as 35% of the SUSY QCD corrections.     

B\to \pi \rho, \pi \omega decays in perturbative QCD approach

We calculate the branching ratios and CP-asymmetries for , and decays, in the perturbative QCD approach. In this approach, we calculate non-factorizable and annihilation type contributions, in addition to the usual factorizable contributions. Our result is in agreement with the branching ratio of , measured by the CLEO and BABAR collaborations. We also predict large CP-asymmetries in these decays. These channels are useful to determine the CKM angle . Received: 5 November 2001 / Published online: 8 February 2002