Electromagnetic and CP violating effects as the origin of the departures from the exact ΔI = 12 rule

In the following we investigate the possibility that the departures from the exact $\text{ΔI =}\text{1}\text{2}$ rule in the B → B′π decays can be explained with mechanisms other than the contributions of the 27-plet. We find model dependent indications that electromagnetic and CP violating effects may account for these departures. Experiments involve large errors, and we cannot test our conjectures with the available data. We also show that the Λπ phase shifts determined from the Ξ and Ξ⁰ decays are not consistent with the time reversal invariance.     

CP-violating asymmetries inη′K and direct CP violation searches with BABAR in charmless hadronicB meson decays

We present preliminary results of the measurement of branching fractions and CP violating asymmetries inB meson decays toη′K and ØK*. We update also the results of the direct CP violation searches with BABAR in charmless hadronicB meson decays.     

Production of D*+(2010) mesons by high energy neutrinos from the Tevatron

We discuss some issues arising in the search for CP violation in the decays Z → τ⁺ τ^? and Z → bb?X. The form-factor and the effective Lagrangian approach to parametrize CP-violating effects are compared. We emphasize the interest to study both real and imaginary parts of CP-violating form factors like the weak dipole moment form factor ${d_?u^Z}={(m_Z^2)}$ of the τ-lepton. We propose an “optimal” way to search for CP violation when Z → bb?X events have to be selected on a statistical basis from the total number of Z hadronic decays.     

B-physics results from the Large Hadron Collider

An overview of the first B-physics results from the LHC is presented, among which are various aspects of b production, rare B decays and CP violation.     

CP violation in decay rates of charged bottom mesons

In the standard theory we discuss a mechanism of interference between two different tree-level charged current amplitudes to induce CP violation. The asymmetry between conjugate Cabibbo disfavoured modes of charged bottom meson decays is considered. Estimates for two-body decays ofB _u andB _c are presented. We find thatB _u ^? →D ^?+D ₀ ^* , for instance, can give a big CP asymmetry with values ≈1–50%, depending on the angle and phase parameters.     

Tests of the standard model and search for new physics using flavor

The vast amount of flavor physics data available to date allows probing the presence of physics beyond the standard model through precision measurements of CP violating and CP conserving processes involving B, D, and K mesons. The information extracted from these measurements allows the characterization of physics beyond the standard model in a complementary way with respect to the direct searches at the Tevatron and the LHC. We review the status of the search for new physics with flavor-related observables. We discuss the status of the unitarity triangle analysis beyond the standard model: the inclusion of the recent measurements of B_s decays from the Tevatron experiments point to a discrepancy from the standard model expectation. In addition, we discuss the impact of O(Λ_QCD/m_b) corrections to the perturbative calculation of charmless hadronic B decays. These corrections can explain the puzzling values of direct CP asymmetries in B→Kπ decays within the standard model. These corrections cannot explain values of sin2β lower than the standard model value, as observed in b→s penguin decays. We conclude with the perspectives of the next generation of flavor-physics experiments, the precision they can reach and their phenomenological impact.     

CP violation in a multi higgs doublet model

We study CP violation in a multi-Higgs doublet model based on aS ₃×Z ₃ horizontal symmetry. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalarpseudoscalar mixings. We find that the predictions for ε′/ε, CP violation in B decays and the electric dipole moments of neutron and electron are different between these two mechanisms. These predictions are also dramatically different from the minimal Standard Model predictions.     

Multiparameter dimensionless complex determining the compression dynamics of a cylindrically symmetric Z-pinch in a gas

For the initial compression stage of a cylindrically symmetric Z-pinch in a gas, on the basis of the energy balance of the discharge we derived a dimensionless equation of the relative radius of its plasma cord, containing a generalized variable, i.e., a multiparameter complex Ξ which determines the discharge compression dynamics and is a result of generalization of experimental data. It is shown that the experimental dependence of the relative plasma cord maximum temperature on the complex Ξ has a tendency to saturation, which is due to the rapid increase in Z-pinch radiation intensity in deuterium upon cord compression.     

Method for determining the D0-D0 mixing parameters

We propose a new method to determine the mass and width differences of the two D meson mass eigenstates as well as the CP violating parameters associated with D0-D[over ]0 mixing. We show that an accurate measurement of all the mixing parameters is possible for an arbitrary CP violating phase, by combining observables from a time dependent study of D decays to a doubly Cabibbo suppressed mode with information from a CP eigenstate. As an example we consider D0-->K*0pi0 decays where the K*0 is reconstructed in both K+pi- and K(S)pi0. We also show that decays to the CP eigenstate D-->K+K- together with D-->K+pi- decays can be used to extract all the mixing parameters. There is a fourfold ambiguity in the solutions for x and y in both the cases. A combined analysis using D0-->K*0pi0 and D-->K+K- can also be used to reduce the ambiguity in the determination of parameters.     

≡ Hypernuclei

We consider the possibility of forming doubly strange Ξ hypernuclei via the (K^?, K) reactions on various nuclear targets. Because of the high momentum transfer involved, even at 0°, the formation of high spin states is strongly favored. The available experimental information on the elementary processes K^?p → K⁺Ξ^? or K⁰Ξ⁰ is reviewed, leading to the determination of an optimum incident K^? momentum of about 1.9 GeV/c for the forward formation of discrete Ξ hypernuclear states. The cross section for the process ΞN → ΛΛ, responsible for the damping width of Ξ states in nuclei, is estimated theoretically and the very limited experimental data are also reviewed. The resulting Ξ hypernuclear widths are of order 5 MeV. Emulsion data which have been interpreted as due to the existence of ΛΛ and Ξ^? hypernuclei are discussed and used to obtain an approximate Ξ nuclear well-depth of 21–24 MeV. For this range of values, spectra of single particle Ξ^? states are obtained, and calculated angular distributions for the formation of simple Ξ^? particle-proton hole states in ⁴He, ¹²C and ²⁸Si targets are presented. The peak 0° lab cross section at p_lab = 1.9 GeV/c for such states ranges from tens of $\text{nb}\text{sr}$ to about 1 $\text{μ}\text{b}\text{sr}$. We briefly mention other methods for forming Ξ hypernuclei, such as the three body reaction K^?N → KπΞ (or $\text{K}{}^{\mathrm{?}}\text{p → K}{}^{\mathrm{+}}\text{K}{}^0\text{Ω}{}^{\mathrm{?}}$ for $\text{Ω}{}^{\mathrm{?}}$ hypernuclei).     

CP violation in two-body hadronic decays of B_c mesons

Using the next-to-leading-order low-energy effective Hamiltonian, the CP asymmetries for -meson decays into meson pairs are calculated in the spectator approximation. We do not compute the hadronic matrix elements directly; instead, we use the amplitude ratios to estimate the CP asymmetries. This is quite different from previous treatments in the literature. The values of the momentum squared carried by the virtual particles in timelike penguin diagrams are also carefully discussed. From our calculated results, the best decay modes to observe CP violation in decays would be , , , , and , each of them needs about of events in experiment. Received: 17 December 1998 / Published online: 30 June 1999     

High transverse momentum Ξ baryon correlations in p+p collisions at √s=200 GeV

Angular correlations between produced high-p _TΞ^? baryons and unidentified charged and neutral particles are observed in high-tower triggered (on a large electromagnetic energy deposit) √s=200 GeV p+p collisions. This trigger favors events with higher average multiplicity than those in minimum bias. These events are likely to contain jets. The average multiplicity of a high-tower triggered event is similar to that of a minimum bias event containing a Ξ baryon, which implies that Ξ baryons are likely to be produced in jets. Ξ^? <p _T> is higher in the triggered data then in the minimum bias sample.     

Evidence for D0-D0 mixing

We observe evidence for D(0)-D(0) mixing by measuring the difference in the apparent lifetime when a D(0) meson decays to the CP eigenstates K(+)K(-) and pi(+)pi(-) and when it decays to the final state K(-)pi(+). We find the relative difference of the lifetimes y(CP) to be [1.31+/-0.32(stat)+/-0.25(syst)]%, 3.2 standard deviations from zero. We also search for a CP asymmetry between D(0) and D(0) decays; no evidence for CP violation is found. These results are based on 540 fb(-1) of data recorded by the Belle detector at the KEKB e(+)e(-) collider.     

Implications of the LHCb evidence for charm CP violation

The LHCb collaboration recently announced preliminary evidence for CP violation in D meson decays. We discuss this result in the context of the standard model (SM), as well as its extensions. In the absence of reliable methods to evaluate the hadronic matrix elements involved, we can only estimate qualitatively the magnitude of the non-SM tree level operators required to generate the observed central value. In the context of an effective theory, we list the operators that can give rise to the measured CP violation and investigate constraints on them from other processes.     

Spontaneous CP violation and neutral B meson decays

A model in which CP is spontaneously broken is described; it solves the strong CP problem and provides an additional mechanism for weak CP violation. This is the aspon model. Application to B decays leads to predictions for CP asymmetries much smaller than expected from the KM mechanism of explicit CP breaking.     

Measuring and fully testing KM unitarity in\Upsilon (4S) \to B_d \bar B_d decays

It is usually suggested to measure the three angles ?₁, ?₂ and ?₃ of the KM unitarity triangle via the CP asymmetries in the reactionsB _d →ψK _S ,B _d →ππ andB _s →K _S ρ^O respectively. There are obviously many major obstacles to the successful completion of such a program; of those two will be addressed in this note: (i) The CP asymmetry inB _d →ππ could a priori be affected by strong final state interactions that depend on long distance dynamics. (ii) The expected rapid rate of \(B_s - \bar B_s\) oscillations will make it very difficult to measure CP asymmetries inB _s decays. I describe various methods for extracting ?₂ and ?₃ directly from CP asymmetries inB _d decays even in the presence of significant strong final state interactions.     

CP noninvariance and the possibility of a sizable neutron electric dipole moment

The electric dipole moment of the neutron will be measured to a precision of 10^?25 e-cm in the near future. We explore a new theoretical possibility that P and CP noninvariance leads to a sizable electric dipole moment. We calculate an electric dipole moment of about 10^?25 e-cm. In this phenomenological theory, we calculate CP-violating observables in non-leptonic decays from theK ⁰ ? \(\bar K^0 \) ,Λ ⁰ ?Λ ⁰ andK ⁺?K ^? systems. In connection with CP noninvariance, the possible observable occurrence of ΔS=2 decays is discussed. We calculate possible branching ratios; in particular that forΞ ⁰ → π^? p can be as high as about 10^?6. The possible existence of a weakly interacting, neutral scalar boson, which violates P and CP in the course of its propagation as a virtual particle, is considered.     

Charmed penguin versus BAU

Since the Standard Model most probably cannot explain the large value of CP asymmetries recently observed in D-meson decays we propose the fourth quark-lepton generation explanation of it. As a byproduct weakly mixed leptons of the fourth generation make it possible to save the baryon number of the Universe from erasure by sphalerons. An impact of the 4th generation on BBN is briefly discussed.