Status ofV ub measurement with BELLE detector

Semileptonic decays ofB →X _u lv have great importance both from theoretical and experimental point of view, as they are useful for extracting the magnitude ofV _ub, one of the tiniest elements of CKM matrix. Similarly measurement ofB √ D_s×_u can be used to calculateV _ub The Belle Collaboration has measured these branching ratios and extractedV _ub for various theoretical models.     

New physics hints in B decays and collider outlook

There are currently two hints for new physics involving CP violation in b → s transitions: ΔS ≡ S _f − S _J ^ϕK ≠ 0, and difference in direct CP asymmetry ΔA _Kπ ≡ A _K+π ⁰ − A _K+π ⁻ ≠ 0. We explore the two scenarios with a large and unique new CP phase in b ↔ s transitions. Motivated by ΔS ≠ 0, we update on the right-handed strange-beauty squark sb _1R at TeV scale. Motivated by ΔA _Kπ ≠ 0, we explore sequential fourth generation t′ and b′ quarks. Both scenarios can survive constraints such as SM level b → sγ, sll and B _s mixing, and predict sizable CP violation in B _s mixing. The fourth generation picture predicts sizable K _L → π ⁰ vv. Direct search for sb _R, b′ and t′ at hadronic colliders, such as Tevatron Run II and LHC, can complement further CP violation studies at these machines, as well as at the future Super B factory.     

Final-state polarization in <Emphasis Type="Italic">B</Emphasis><Stack><Subscript><Emphasis Type="Italic">s</Emphasis></Subscript><Superscript>0</Superscript></Stack> decays

Certain B _s ⁰→V ₁ V ₂ decays (V _i is a vector meson) can be related by flavor SU(3) symmetry to corresponding B _d ⁰→V ₃ V ₄ decays. In this paper, we show that the final-state polarization can be predicted in the B _s ⁰ decay, assuming polarization measurements of the B _d ⁰ decay. This can be done within the scenario of penguin annihilation (PA), which has been suggested as an explanation of the unexpectedly large transverse polarization in B→φ K ^*. PA is used to estimate the breaking of flavor SU(3) symmetry in pairs of decays. Two of these for which PA makes a reasonably precise prediction of the size of SU(3) breaking are (B _s ⁰→φ φ,B _d ⁰→φ K ^0*) and ( ). The polarization measurement in the B _d ⁰ decay can be used to predict the transverse polarization in the B _s ⁰ decay and will allow for testing of PA as well as the other assumptions in the analysis.     

Strong isospin violation andη−π mixing in |ΔS|=1 weak transition

We consider the effects ofη−π mixing on the violation of the |ΔI|=1/2 rule in |ΔS|=1 weak transitions. The processes considered are theK→2π,K→3π, Λ, Ξ and Λ hyperon decays.     

Improved measurement of theB0 andB+ meson lifetimes

The lifetimes of theB ⁰ andB ⁺ mesons have been measured with theAleph detector at LEP, using approximately 3 million hadronic Z decays collected in the period 1991–1994. In the first of three methods, semileptonic decays ofB ⁰ andB ⁺ mesons were partially reconstructed by identifying events containing a lepton with an associatedD*⁻ or meson. The second method used fully reconstructedB ⁰ andB ⁺ mesons. The third method, used to measure theB ⁰ lifetime, employed a partial reconstruction technique to identifyB ⁰→D*⁻ π ⁺ X decays.     

Phenomenological applications of<Emphasis Type="Italic">k</Emphasis><Subscript>T</Subscript>factorization

We discuss applications of the perturbative QCD approach in the exclusive non-leptonic two-bodyB-meson decays. We briefly review its ingredients and some important theoretical issues on the factorization approach. PQCD results are compatible with present experimental data for charmless B-meson decays. We predict the possibility of large direct CP asymmetry in B⁰ → π⁺π⁻ (23 +7%) and B⁰ →K ⁺π⁻ (− 17 ± 5%). We also investigate the branching ratios, CP asymmetry and isospin symmetry breaking in radiativeB →(K*/ρ)γ decays.     

Production rate and decay lifetime measurements ofBs0 mesons at LEP usingDs and? mesons

The study of the properties of inclusive production ofD _s mesons and of events in which a and a muon are present in the same jet provides two independent measurements of the probability,f _s ^w , for a heavy quark to hadronize into a strangeB orD meson. The data sample analysed corresponds to 243,000 hadronicZ ⁰ decays. The combined value of these measurements isf _s ^w =0.19±0.06±0.08. From the flight distance distributions ofD _s and of (-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, two values are obtained for theB _s ⁰ meson lifetime. Combining these measurements with a previous result based on the study ofD _s- events, theB _s ⁰ meson lifetime is measured to be: 0.96±0.37 ps.     

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.     

B-decay CP-asymmetries in SUSY with a U(2)3 flavour symmetry

We study CP asymmetries in rare B decays within supersymmetry with a U(2)³ flavour symmetry, motivated by the SUSY flavour and CP problems, the hierarchies in the Yukawa couplings and the absence so far of any direct evidence for SUSY. Even in the absence of flavour-blind phases, we find potentially sizable CP violating contributions to b→s decay amplitudes. The effects in the mixing-induced CP asymmetries in B→ϕK _S and B→η′K _S , angular CP asymmetries in B→K ^∗ μ ⁺ μ ⁻ and the direct CP asymmetry in B→X _s γ can be in the region to be probed by LHCb and next generation B factories. At the same time, these effects in B decays are compatible with CP violating contributions to meson mixing, including a non-standard B _s mixing phase hinted by current tensions in the CKM fit mostly between S_yKS, e_KS_{\psi K_{S}}, \epsilon_{K} and DM_Bs/DM_Bd\Delta M_{B_{s}}/\Delta M_{B_{d}}.     

Charm changing weak decays 1/2+ → 3/2+ + 0−/γ in SU(4) and SU(8) w

Weak decay modes (1/2⁺ → 3/2⁺ + 0⁻/γ) of charmed baryons are studied. Relations among the various decay amplitudes are derived in isospin, SU(3), SU(4) and SU(8) _w symmetries. Sextet dominance in SU(3) forbidsB(3) →D(10) +P(3*) decays. 20″ dominance in SU(4) specifies all the decays in terms of Θ⁻ decays. Weak decays of Θ* ₃ ⁺⁺ and Θ⁻ are also discussed. SU(8) _w symmetry predictsα , which is consistent with the experimental value.     

Ratio of the color suppressed decays Λ b →ΛJ/ψ andB 0→KJ/ψ

Based on the factorization approximation, we have estimated the ratio of the branching fractions for the color suppressed nonleptonic decays Λ _b →ΛJ/ψ andB ⁰→KJ/ψ. Treating thes-quark as heavy, we have used the HQET to calculate the hadronic matrix elements. The mesonic Isgur-Wise function is calculated in the quark model whereas for the baryonic IW function we have employed the bound state soliton picture. The results obtained agree very well with the recent CDF experimental data.     

B c meson properties and its leptonic radiative decays

The properties of the meson B _c are outlined. The leptonic radiative decays for B _c meson are presented. An outlook on the studies of the meson is given.     

Hadronic weak decays of heavy mesons and nonfactorization

The parametersχ _1,2, which measure nonfactorizable soft gluon contributions to hadronic weak decays of mesons, are updated by extracting them from the data ofD, B→PP, VP decays (P: pseudoscalar meson,V: vector meson). It is found thatχ ₂ ranges from −0.36 to −0.60 in the decays fromD→Kπ toD ⁺→φπ ⁺,D→K*π, while it is of order 10% with a positive sign inB→ψK, Dπ, D*π, Dρ decays. Therefore, the effective parametera ₂ is process dependent in charm decay, whereas it stays fairly stable inB decay. This is in accordance with the picture that nonfactorizable soft gluon effects become stronger when the relative momentum of the decay particles becomes smaller. As forD, B→VV decays, the presence of nonfactorizable terms in general prevents a possible definition of effectivea ₁ anda ₂. This is reinforced by the observation of a large longitudinal polarization fraction inB→ψK* decay, implying nonfactorizable effects contributing differently toS-, P- andD-wave amplitudes. We found thatA ₁ ^nf /A ₁>0>A ₂ ^nf /A ₂,V ^nf/V (nf standing for nonfactorization) forB→ψK* decay and 0>A ₁ ^nf /A ₁>A ₂ ^nf /A ₂,V ^nf/V forD→K*ρ decay. A measurement of longitudinally and transversely polarized decay rates Γ _L and Γ _T in color-suppressed decay modesB ⁰→D*⁰ ρ ⁰,D*⁰ ω andD ⁺→φρ ⁺ is urged.     

Theψ-particles in an SU4 scheme with anomalous currents

The recently discovered narrow peaks (theψ-particles) in e⁺e⁻ system at 3.105 and 3.695 GeV are interpreted as hadrons in a broken SU₄ symmetry scheme. A new additional additive quantum number, parachargeZ, is combined with the usual SU₃ quantum numbers in the group SU₄. Theψ (3.1) is assigned to a near ideally mixed15⊕1 multiplet of vector mesons (containing theρ) as theI=Y=0, charge conjugationC=−combination ofZ=±1.members. Theψ (3.7) is assigned correspondingly to another mixed15⊕1 multiplet containing theρ′ (1600). The hadronic electromagnetic interactions are modified by the addition of (non-minimal) anomalous pieces that can changeZ. The decays of theψ-particles are discussed. New enlarged SU₄ multiplets of other hadrons are proposed. Tests of our scheme are put forward. The most crucial test will be the observation of two rather broad resonances in e⁺ e⁻ collisions with masses around 4.2 GeV and 5.1 GeV. Another prediction is the presence of energetic photons in the decays of theψ-particles. Important results concerning the recently observed phenomena in the process e⁺e⁻→hadrons follow in this scheme.     

Paracharge phenomenology: systematics of the new hadrons

A systematic semiquantitative account of all aspects of the strong and electromagnetic interactions of all the newly discovered hadronic states (theψ’s, theχ’s, etc.) is presented within the framework of the paracharge scheme. Extensions of ideas familiar from the SU₃ classification scheme to SU₄ are shown to provide an understanding of the new states seen in the decays ofψ (3.1) andψ′ (3.7), including their masses and gross decay characteristics. The decays ofψ (3.1) andψ′ (3.7) themselves are studied in some detail. Since these are of electromagnetic origin in the scheme, their electromagnetic mixing with the resonance at 4.15 GeV (theP-state of the scheme) is important. Once this is taken into account, the resulting picture is in excellent agreement with available data.     

Inclusive photon energy spectrum in rareB decays

Inclusive photon energy spectrum and decay rate for the rare radiative decays of theB hadrons,B +X _s (hereX _s denotes hadrons with total strangeness quantum numberS=–1), are calculated in the standard theory of electroweak interactions, using theb quark decay model. The calculations have been done in the framework of an effective low-energy Lagrangian based on the gauge invariant operators of dimension 6. The large QCD effects, contained in the Wilson coefficients of these operators, are included in our approach. The shape of the photon energy spectrum and the branching ratio BR (B+X _s ) are sensitive to the top quark mass.     

Hadronic decays from the lattice

I review the lattice QCD approach to determining hadronic-decay transitions. Examples considered include ρ→ππ; b ₁→πω; hybrid meson decays and scalar meson decays. I discuss what lattices can provide to help understand the composition of hadrons.     

Dipionic decays of psions in a local derivative coupling model

A local derivative coupling model is used to study theφ′→ππ and other dipionic decays ofφ andφ″, as an alternative to theε-model. The results obtained are quite satisfactory. We findt hat the existence of theε-resonance is not essential in order to understand the dipionic decays of the psions at the present level of experimental data available. A preliminary version of this paper was presented at the 3rd High Energy Phys. Symp. held in Nov. 1976 at Bhubaneswar.     

Shape distortions of meson resonances produced in hadron interactions atP T≧2 GeV/c

Using the ARGUS detector at thee ⁺ e ^– storage ring DORIS II, flavour-dependent kaon production inB meson decays has been studied. Using the leptons as flavour tags, it has been possible to separately measure the multiplicities ofK ⁺,K ^– andK _s ⁰ in inclusiveB decays and in semileptonicB decays. The kaon production in semileptonicB decays was further used to estimate the ratio of charmed decays over all decays, and thus also the fraction of charmlessB decays.DESY, IfH Zeuthen     

Mesonic decays of τ− lepton: Effects of neutrino mass and mass mixing

Experimentally established mesonic decays ofτ ⁻ lepton have been reexamined with the inclusion of the effects of finite neutrino mass and the associated mass mixing in the form of Kobayashi-Maskawa mixing matrix. A comparison with the experimentally predicted decay probabilities provides limits for thev _τ mass which are finite in all decays except for the lower limit in mass mixing case of the decayτ ⁻→K*⁻ (892)+v _τ for which MeV. The large error in this value is because of (i) large errors in the experimental values of life time and branching ratio for this decay and (ii) thekm mixing used in the calculations. The ratio of parity-violating to parity-conserving terms in the differential decay probabilities of various decays differs slightly from their values corresponding to those with varishingv _τ mass.