About detecting CP-violating processes in J/ψ→ K^0K^-0 decay

Abstract Questions about detecting the CP-violating decay process of J/ψ→ K^0K^-0→ KsKs are discussed. Possible background and material regeneration effects are analyzed. The discussion can be directly extended to other vector quarkonium decays, like γ, ψ（2S） and Ф → KsKs.     

Branching fractions and direct C P asymmetries of ■_s →K~0h~+h′~-(h(′)=K,π) decays

Motivated by the recent LHCb collaboration measurements of charmless three-body decays of ■s meson, we calculate the branching fractions of ■ s →K0π+π-, ■s→K0K+K-, ■s→K0π+K- and ■s→K0K+π- decay modes using the factorization approach.Both the resonant and nonresonant contributions are studied in detail. For the decays ■s→K0π+π- and ■s→K0K+K-, our results agree well with experimental data, and the former is dominated by the K*, while the latter one is dominated by the nonresonant contribution. Considering the flavor S U(3) symmetry violation, the sum of branching fractions of ■s→K0π+K- and ■s→K0K+π-could accommodate the data well too. It should be noted that both branching fractions are sensitive to the scalar density Kπ|ˉsq|0.Furthermore, the resonant contributions are dominated by the scalar K*0(1430). We hope that these branching fractions could be measured individually in the experiments so as to test the factorization approach and the flavor S U(3) asymmetry. Moreover, the direct C P asymmetries of these decays are also investigated, which could be measured in the running LHCb experiment and Super-b factory in the future.     

Reanalysis of the （0^＋, 1^＋） States Bs0 and Bs1 with QCD Sum Rules

We calculate the masses and decay constants of the P-wave strange-bottomed mesons Bs0 and Bs1 with the QCD sum rules, and observe that the central values of the masses Bs0 and Bs1 are smaller than the corresponding BK and B^＊K thresholds respectively, the strong decays Bs0→ BK and Bs1→B^＊K are kinematically forbidden. They can decay through the isospin violation processes Bs0→ Bsη → Bsπ^0 and Bs1 → Bs^＊η → Bs^＊π^0 .The bottomed mesons Bs0 and Bs1, just like their charmed cousins Ds0（2317） and Ds1（2460）, may be very narrow.     

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

Based. On the effective Hamiltonian with the generalized factorization approach, we calculate the branchingratios and CP asymmetries of B → VV decays in the Topcolor-assisted Technicolor (TC2) model. Within the consideredparameter space we find that: (a) for the penguin-dominated B → K* φ and K*0 φ decays, the new physics enhancementsto the branching ratios are around 40%; (b) the measured branching ratios of B →K* φ and K*0φ decays prefer therange of 3 Neffc 5; (c) the SM and TC2 model predictions for the branching ratio B(B →ρ ρ0) are only about halfof 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 mπ and Neffc.     

Branching ratio and CP asymmetry of Bs→K0(1430)η(') decays in the PQCD approach

In the two-quark model supposition for K0*(1430), which can be viewed as either the first excited state (ScenarioⅠ) or the lowest lying state (Scenario Ⅱ), the branching ratios and the direct CP-violating asymmetries for decays s0 → K0*0(1430)η (’) are studied by employing the perturbative QCD factorization approach. We find the following results: (a) The CP averaged branching ratios ofs0 → K0*0 (1430)η ands0→ K0*0(1430)η’ are small and both in the order of 10-7 . If one views K0* (1430) as the lowest lying state, B(s0→K0*0(1430)η) ≈ 3.9×10-7 and B(s0→K0*0(1430)η’) ≈ 7.8×10-7.(b) While the direct CP-violating asymmetries of these two decays are not small: if we still take the parameters of K0* (1430) in scenario , ACPdir(s0→K0*0(1430)η) ≈ 56.2% and ACPdir(s0→ K0*0(1430)η’) ≈ 42.4%. (c) The annihilation contributions will play an important role in accounting for future data, because both the branching ratios and the direct CP asymmetries of these two decays are sensitive to the annihilation type contributions.     

KLOE results on light mesons

The KLOE collaboration has recently published new results concerning scalar and pseudoscalar mesons.Here the φ → a 0 （980）γ → ηπ 0 γ decay analysis and the search for the φ → K 0 K 0 γ decay are discussed,together with the η → π ＋ π-e ＋ edecay measurements annd the new results for the pseudoscalar mixing angle and gluonium content of the η’ meson.     

KLOE results on light mesons

The KLOE collaboration has recently published new results concerning scalar and pseudoscalar mesons.Here the φ→ a 0 (980)γ→ηπ 0 γ decay analysis and the search for the φ→ K 0 K 0 γ decay are discussed,together with the η→π + π-e + edecay measurements annd the new results for the pseudoscalar mixing angle and gluonium content of the η’ meson.     

B-Meson Wavefunction by a Comparative Analysis of the B → π, K Transition Form Factors

Properties of the B-meson light-cone wavefunction up to next-to-leading order Fock state expansion are studied by a comparative study of the B → π, K form factors within the kT factorization approach and the light-cone sum rule analysis. The form factors F＋,0,T^B→ π and F＋,0,T^B→ K are carefully re-calculated up to O（1/mb^2） within the kT factorization approach in the large recoil region. The QCD light-cone sum rule is applicable in the large and intermediate energy regions, and the QCD light-cone sum rule results in Ref. [12] are adopted for such a comparative study. It is found that when the two phenomenological parameters ∧^-∈ [0.50, 0.55] and δ∈ [0.25, 0.30], the results of F＋,0,T^B→ π （Q^2 ） and F＋,0,T^B→ K（Q ^2） from these two approaches are consistent with each other in the large recoil energy region.     

Charm mixing from BABAR

We present recent results from BABAR experiment for D0-D0 mixing measurements. Mixing parameters can be measured in different ways using different D0 decay modes, here we discuss the most sensitive analyses such as DO→K+π- where we had the first evidence of charm mixing, the measurement of the ratio of lifetimes of the decays DO→K+K-and DO→π- relative to D0→K-π+, the time dependent Dalitz plot analysis of D0→K+π-π0.New limits on CP-violating time-integrated asymmetries in D0→K+K- and D0→π+π- are also discussed. The analyses presented are based on 384 fb-1 data collected with the BABAR detector at the PEP-Ⅱ asymmetric B Factory.     

Triangle singularity enhancing isospin violation in B~0_s→ J/ψπ~0f_0(980)

We perform calculations for theB~0_s→J/ψπ~0f_0(980) andB~0_s→J/ψπ~0a_0(980) reactions, showing that the first is isospin-suppressed while the second is isospin-allowed. The reaction proceeds via a triangle mechanism, with B~0_s→J/ψK* Kˉ+c.c., followed by the decay K*→Kπ and a further fusion of K Kˉ into the f0(980) or a0(980). We show that the mechanism develops a singularity around the π~0f_0(980) or πa_0(980) invariant mass of 1420 Me V, where the π~0f_0 and π~0a_0 decay modes are magnified and also the ratio of π~0f_0 to π~0a_0 production. Using experimental information for theB~0_s→J/ψK* Kˉ+c.c. decay, we are able to obtain absolute values for the reactions studied which fall into the experimentally accessible range. The reactions proposed and the observables evaluated, when contrasted with actual experiments, should be very valuable to obtain information on the nature of the low lying scalar mesons.     

Recent results on light hadron spectroscopy from BES Ⅱ

We reported the observation of Y(2175) in φf0(980) mass spectrum in J/ψ→ηφf0(980) with f0(980)→π+π- and the observation of a broad 1-- resonance of K+K-mass in J/ψ→K+K-π0. The results from the partial wave analyses of Jψ→γπ+π- and γπ0π0, as well as J/ψ→pK-∧. are also presented.     

K-p scattering and hyperon excitations in a chiral quark model

A chiral quark-model approach is employed to study theˉ KN scattering at low energies.The processes of Kˉp →Σ 0 π 0,Λπ 0 andˉ K 0 n at P K 800 MeV/c (i.e.the center mass energy W 1.7 GeV) are investigated.The analysis shows that the Λ(1405)S 01 dominates the processes Kˉp →Σ 0 π 0,ˉ K 0 n in the energy region considered here.Around P K 400 MeV/c,the Λ(1520)D 03 is responsible for a strong resonant peak in the cross section of Kˉp →Σ 0 π 0 andˉ K 0 n.To reproduce the data,an unexpectedly large coupling for Λ(1520)D 03 to KN is needed.In contrast,the coupling for Λ(1670)S 01 to KN appears to be weak,which could be due to configuration mixings between Λ(1405)S 01 and Λ(1670)S 01 .By analyzing Kˉ p →Λπ 0,evidences for two low mass S-wave states,Σ(1480)S 11 and Σ(1560)S 11,seem to be available.With these two states,the reaction Kˉp →ˉ K 0 n can also be described well.However,it is difficult to understand the low masses of Σ(1480)S 11 and Σ(1560)S 11 .The s-channel amplitudes for Kˉp →Λπ 0 are also larger than the naive quark model expectations.The non-resonant background contributions,i.e.t-channel and/or u-channel,also play important roles in the explanation of the angular distributions due to amplitude interferences.     

K－p scattering and hyperon excitations in a chiral quark model

A chiral quark-model approach is employed to study theˉ KN scattering at low energies.The processes of Kˉp → Σ 0 π 0,Λπ 0 andˉ K 0 n at P K 800 MeV/c （i.e.the center mass energy W 1.7 GeV） are investigated.The analysis shows that the Λ（1405）S 01 dominates the processes Kˉp → Σ 0 π 0,ˉ K 0 n in the energy region considered here.Around P K 400 MeV/c,the Λ（1520）D 03 is responsible for a strong resonant peak in the cross section of Kˉp → Σ 0 π 0 andˉ K 0 n.To reproduce the data,an unexpectedly large coupling for Λ（1520）D 03 to KN is needed.In contrast,the coupling for Λ（1670）S 01 to KN appears to be weak,which could be due to configuration mixings between Λ（1405）S 01 and Λ（1670）S 01 .By analyzing Kˉ p → Λπ 0,evidences for two low mass S-wave states,Σ（1480）S 11 and Σ（1560）S 11,seem to be available.With these two states,the reaction Kˉp →ˉ K 0 n can also be described well.However,it is difficult to understand the low masses of Σ（1480）S 11 and Σ（1560）S 11 .The s-channel amplitudes for Kˉp → Λπ 0 are also larger than the naive quark model expectations.The non-resonant background contributions,i.e.t-channel and/or u-channel,also play important roles in the explanation of the angular distributions due to amplitude interferences.     

Recent results from NA48/2

Recent results on radiative K± decays from the NA48/2 experiment are reported.From the full NA48/2 data set,about a million K±→π±π0γ decays were reconstructed.Based on this sample,the first measurement of the interference between direct photon emission and inner bremsstrahlung in K±→π±π0γ decays was performed.Stringent limits on CP violation in this decay were also set.In addition,a precise measurement of the branching fraction of K±→π±γγ is presented.This measurement was based on a data sample of more than 1000 event candidates.Also the related decay K±→π±e+e-γ has first been observed.Results of the measurement of the decay rate and the decay parameter c are summarized.     

B→K0^＊（1430）K Decays in Perturbative QCD Approach

In this article, we calculate the branching ratios of B→K0^＊ （1430）K decays by employing the pertur-bative QCD （pQCD） approach at leading order. We perform the evaluations in the two scenarios for the scalar meson spectrum. We find that （i） The leading order pQCD predictions for the branching ratio Br（B^＋→K^＋K0^＊（1430）^0）are in good agreement with the experimental upper limit in both scenarios, while the pQCD predictions for other considered B→K0^＊（1430）K decay modes are also presented and will be tested by the LHC experiments; （ii） The annihilation contributions play an important role in these considered decays, for B^0→K0^＊（1430）^±K^± decays,for example,which are found to be （1-4）×10^-6.     

Measuring D~0-~0mixing in D→f_0(980)K~* and more

We investigate the D0-0 mixing through the doubly Cabibbo suppressed (DCS) channel D0 →f0(980)K0 and its charge conjugate channel, in which the K0 meson is reconstructed in both K π- and KSπ0 final state. Although the decay D0 →f0(980)K* has a small branching ratio, the final state mesons are relatively easy to identify. The f0(980) meson can be replaced by the S-wave π π- state, or a longitudinally polarized vector meson ρ0. All mixing parameters, including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels. We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

Baryon ＋ Baryon→（ΩΩ）J^π=0＋ ＋ X Cross Section Calculation

The cross sections of Ω Ξ→（ΩΩ）J^π=0 K(K^*) and Ω Ω→（ΩΩ）J^π=0 η‘(φ) are studied by using an effective Hamiltonian method.For the two pseudo-scalar meson production processes,the cross sections are still in the order of several μbs,but for the two vector meson production processes,the cross sections are about 10 times larger than those in pseudo-scalar meson production case when the coupling constants of vector meson fields are fixed according to gNNρ and fNNρ in NN scattering and the SU(3) relation.     

Cross sections for inelastic 2-to-2 meson-meson scattering in hadronic matter

With quark-antiquark annihilation and creation in the first Born approximation, we study the reactions:K■→K■~*,K■→K~*■, πK→πK~*, πK→ρK, ππ→ K■~*, ππ→K~*■,ππ→K~*■~*,πρ→K■, πρ→K~*■~*,ρρ→K~*■~*, K■~*→ρρ, and K~*■→pp. Unpolarized cross sections for the reactions are obtained from transition amplitudes that are composed of mesonic quark-antiquark relative-motion wave functions and the transition potential for quark-antiquark annihilation and creation. Using a quark-antiquark potential that is equivalent to the transition potential, we prove that the total spin of the two final mesons may not be equal to the total spin of the two initial mesons. Based on flavor matrix elements, cross sections for some isospin channels of reactions can be obtained from other isospin channels of the reactions. Remarkable temperature dependence of the cross sections was observed.     

The Role of α_1(1260) in π~-p→α_1~-(1260)p and π~-p → π~-ρ~0p Reactions Near Threshold

We report on a theoretical study of the π~-ρ→α1(1260)p and π~-ρ→π~-ρ~0p reactions near threshold within an effective Lagrangian approach.The production process is described by t-channel ρ~0 meson exchange.For the π~-ρ→π~- ρ~0p reaction,the final π~-ρ~0 results from the decay of the α1(1260) resonance,which is assumed as a dynamically generated state from the K* K and ρπ coupled channel interactions.We calculate the total cross section of the π~-ρ→α1(1260)p reaction.It is shown that,with the coupling constant of the α1(1260) to ρπ channel obtained from the chiral unitary theory and a cut off parameter Δρ~1.5 GeV in the form factors,the experimental measurement can be reproduced.Furthermore,the total and differential cross sections of π~p→α1(1260)p→π~ρ~0p reaction are evaluated,and it is expected that our model calculations can be tested by future experiments.These reactions are important for the study of the α1(1260) resonance and would provide further constraints on the properties of the α1(1260) state.     

Analysis of B → a_1(1260)(b_1(1235))K decays in the perturbative QCD approach

Within the framework of the perturbative quantum chromodynamics(PQCD) approach, we study the charmless two-body decays B → a_1(1260)K*, b_1(1235)K*. Using the decay constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results.(a) Our predictions for the branching ratios are consistent with the QCD factorization(QCDF) results within errors, but much larger than the naive factorization approach calculation values.(b) We predict that the anomalous polarizations occurring in the decays B→φK*, ρK*also happen in B→a_1 K*decays, while they do not happen in B→b_1 K*decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→a_1 K*decays, while they are not sensitive to the polarizations for the B→b_1 K*decays.(c) Our predictions for the direct C P-asymmetries agree well with the QCDF results within errors. The decaysˉB~0→b_1_+K*-, B-→b_1~0K*-have larger direct C P-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.