Pure annihilation type decays B0→Ds- （K2*）+ and Bs →a2 in the perturbative QCD approach

We calculate the branching ratios of pure annihilation type decays B 0 →D_s^- （K₂^*）⁺ and Bs → a₂ using the perturbative QCD approach based on k T factorization. The branching ratios are predicted to be （60.6 +17.3+4.3+3.2 16.5 10.4 2.1 ）× 10^-6 for B⁰ →D_s^- （K₂^*）⁺ , （1.1 +0.4+0.1+0.1-0.4-0.2-0.1 ）×10-6 for Bs → ⁰a₂⁰ and （2.3 +0.8+0.2+0.1-0.8-0.4-0.1 ）×10-6 for Bs→D^-a₂⁺ . They are large enough to be measured in the ongoing experiment. Due to the shortage of contributions from penguin operators, there are no direct CP asymmetries for these decays in the Standard Model. We also derive simple relations among these decay channels to reduce theoretical uncertainties for the experiments, to test the accuracy of theory, and to search for a signal of new physics.     

Weak decays of doubly heavy baryons:Bcc→BD*

The discovery of Ξ_cc⁺⁺has inspired new interest in studying doubly heavy baryons.In this study,the weak decays of a doubly charmed baryon B_ccto a light baryon B and a charm meson D^*(either a pseudoscalar or a vector one)are calculated.Following our previous work,we calculate the short distance contributions under the factorization hypothesis,whereas the long distance contributions are modeled as the final state interactions,which are calculated with the one particle exchange model.We find that the B_cc→BD^*decays'branching ratios are obviously larger,as they receive contributions of more polarization states.Among the decays that we investigate,the following have the largest branching fractions:BR(Ξ_cc⁺⁺→∑⁺D^*+)∈[0.46%,3.33%]estimated with τΞ_cc⁺⁺=256 fs;BR(Ξ_cc⁺→AD^*+)∈[0.38%,2.63%]and BR(Ξ_cc⁺→∑⁰D^*+)∈[0.45%,3.16%]with τΞ_cc⁺⁺=45 fs;and BR(Ω_cc⁺→Ξ⁰D⁺)∈[0.27%,1.03%),BR(Ω_cc⁺→∑⁰D^*+)∈[0.07%,0.44%],and BR(Ω_cc⁺→∑⁰D^*+)∈[0.06%,0.45%] with τ_(Ω_cc)⁺=75 fs.By comparing the decay widths of pure color commensurate channels with those of pure bow-tie ones we find that the bow-tie mechanism plays an important role in charm decays.     

Hadron molecules

We discuss a possible interpretation of the open charm mesons D*s0 (2317),D s1 (2460) and the hidden charm mesons X(3872),Y(3940) and Y(4140) as hadron molecules.Using a phenomenological Lagrangian approach we review the strong and radiative decays of the D* s0 (2317) and D s1 (2460) states.The X(3872) is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration.Determing the radiative (γJ/ψ and γψ(2s)) and strong (J/ψ2π and J/ψ3π) decay modes we show that the present experimental observation is consistent with the molecular structure assumption of the X(3872).Finally,we give evidence for molecular interpretations of the Y(3940) and Y(4140) related to the observed strong decay modes J/ψ+ω or J/ψ+φ,respectively.     

Non-factorizable contributions in D0→π+π- decay

We have analyzed the D^0→π^+π^- decay with α_s corrections in quantum chromodynamic (QCD) factorization and with the soft-gluon corrections in the light cone QCD sum rules. The soft-gluon effects are firstly calculated in the decay channel. The results show that once the factorization contributions, the α_s corrections, and the soft-gluon effects are all considered, we can satisfactorily explain the experimental data in the decay channel.     

Analysis of B → a1（1260）（b1（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 → a₁（1260）K*, b₁（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→a₁ K*decays, while they do not happen in B→b₁ K*decays. Here the contributions from the annihilation diagrams play an important role in explaining the larger transverse polarizations in the B→a₁ K*decays, while they are not sensitive to the polarizations for the B→b₁ K*decays.（c） Our predictions for the direct C P-asymmetries agree well with the QCDF results within errors. The decaysˉB⁰→b₁₊K*-, B-→b₁⁰K*-have larger direct C P-asymmetries, which could be measured by the present LHCb experiment and the forthcoming Super-B experiment.     

Magnetic and quadrupole moments of the Zc(4020)+,Zc(4050)+,and Zc(4600)+ states in the diquark-antidiquark picture

The magnetic and quadrupole moments of the Z_c(4020)⁺,Z_c(4050)⁺,and Z_c(4600)⁺ states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the distribution amplitudes of the on-shell photon are used to extract the magnetic and quadrupole moments of these states.The magnetic moments are acquired as μ_Zc=0.50_-0.22^+0.22μ_N,μ     

OPTICAL-OPTICAL DOUBLE-RESONANCE EXCITATION SPECTRA OF THE (6d)1Πg, (7d)1Πg HIGH-LYING RYDBERG STATES IN Na2

Two ¹Π_g states of Na₂ for v≤13 have been observed by using optical-optical double resonance (OODR) fluorescence excitation spectroscopy. The intermediate levels in B¹Π_u state are identified by the numerical calculations with the molec-ular constants for B¹Π_u←X¹Σ_g⁺ transitions and confirmed by the complemen-tary A¹Σ_g⁺←X¹Σ_g⁺ polarization spectra. Absolute vibrational numberings of the (6d)¹Π_g and (7d)¹Π_g states are determined by comparing the experimental OODR excitation intensities with the simulated Franck-Condon factors. The Dnnham coef-ficients and the Rydberg-Klein-Rees (RKR) potential energy curves of the (6d)¹Π_g, (7d)¹Π_g states are reported.     

QCD Axial Anomaly Enhances the ηη' Decay of the Hybrid Candidate η1（1855）

We study the hybrid mesons with the exotic quantum number I^GJ^PG=0⁺1^-+ and investigate their decays into the ηη’,a₁（1260）π,f₁（1285）η,f₁（1420）η,K^*（892）■,K₁（1270）■,and K₁（1400）■channels.It is found that the QCD axial anomaly enhances the decay width of the ηη’ channel although this mode is strongly suppressed by the small p-wave phase space.Our results support the interpretation of the η     

Charmed andϕmeson decay constants from 2+1-flavor lattice QCD

On a lattice with 2+1-flavor dynamical domain-wall fermions at the physical pion mass,we calculate the decay constants of D_s^* , D^* ,and φ .The lattice size is 48^3×96 ,which corresponds to a spatial extension of -5.5 fm,with a lattice spacing of a\approx a≈0.114 fm.For the valence light,strange,and charm quarks,we use overlap fermions at several mass points close to their physical values.Our results at the physical point are f_D=213(5) MeV, f_Ds=249(7) MeV, f_D^*=234(6) MeV, f_Ds^*=274(7) MeV,and f_Ds=241(9) MeV.The couplings of D^* and D_s^* to the tensor current( f_V^T )can be derived from ratios f_D^*^T/f_D^*=0.91(4) and f_Ds^*^T/f_Ds^*=0.92(4) ,respectively,which are the first lattice quantum chromodynamics(QCD)results.We also obtain ratios f_D^*/f_D=1.10(3) and f_Ds^*/f_Ds=1.10(4) ,which reflect the size of heavy quark symmetry breaking in charmed mesons.Ratios f_Ds/f_D=1.16(3) and f_Ds^*/f_D^*=1.17(3) can be taken as a measure of SU(3)flavor symmetry breaking.     

Estimation of radiative capture 13B(n,γ0+1)14B reaction rate in the modified potential cluster model

We discuss current attempts to employ the modified potential cluster model to describe the available experimental data on the ¹³B(n,γ₀₊₁)¹⁴B total cross-sections.The estimated results of the M1 and E1 transitions from the n¹³B scattering states to the ground and first excited states of ¹⁴B are presented.The 1^st resonance at E_x=1.275MeV(1⁺) is revealed in both the cross-section and reaction rate.Within the var...     

Mixing of two-quasineutron and two-quasiproton Kπ=6+ configurations in the vicinity of 174Yb

In the framework of the projected shell model, we investigate the competition between the two-quasineutron and two-quasiproton K^π=6⁺ states in the ytterbium isotopes and N =104 isotones adjacent to ¹⁷⁴Yb. The ¹⁷⁴Yb results are compared with the experimental data.The K^π =6⁺ isomer observed in ¹⁷⁴ Yb is assigned as an admixture of the ν7/2^-[514] ν5/2^-[512] and π7/2⁺ [404]π5/2⁺ [402] intrinsic structure, which explains the experimental |g K-g R | value. Similar mixing would appear in ¹⁷⁴ Yb, ¹⁷⁶ Hf,and ¹⁷⁸ W. The low-lying K^π=6⁺ states are also predicted in ^170-178 Yb.     

ORDER αS QCD CORRECTIONS IN DOUBLY DEEP TWO-PHOTON PROCESSES

order α_S QCD corrections to the Process γ^* +γ^* → 2 jets are calculated in the case where both p力otons are far off shell and spacelike, with q₁²/q₂² and S=(q₁+q₂)² fixed. Compared with the leading Iog approximation results, the scaling of the 2-jet cross-section is still. preserved while the angular distri-butibn gets some corrections.     

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.     

Analysis of the decay B0→χclπ0 with light-cone QCD sum rules

In this article,we calculate the contribution from the nonfactorizable soft hadronic matrix element to the decay B~0→χc1~π~0 with the light-cone quantum chromo-dynamic(QCD) sum rules.The numerical results show that its contribution is rather large and should not be neglected.The total amplitudes lead to a branching fraction which is in agreement with the experimental data marginally.     

Determination of the resonant parameters of excited vector strangenia with e+e-→ηφ data

We determine the resonant parameters of the vector states φ(1680) and φ(2170) by performing a combined fit to the e⁺e^-→ηφ cross sections from the threshold to 2.85 GeV measured by the BaBar,Belle,BESⅢ,and CMD-3 experiments.The mass(1678_-3⁺⁵±7) MeV/c² and width(156±5±9) MeV are obtained for φ(1680),and the mass(2169±5±6)MeV/c² and width(96_-14⁺¹⁷±9)MeV are obtained for φ(2170).The statistical significance ofφ(2...     

Zcs(4000)+ and Zcs(4220)+ in a Multiquark Color Flux-Tube Model

We systematically investigate the mass spectrum, spatial configuration and magnetic moment of the ground and p-wave states ■ with various color-spin configurations in a multiquark color flux-tube model. Numerical results indicate that the state Z_cs(4000)⁺ can be described as the compact state ■ with 1³S₁. Its main colorspin configuration is ■ and its magnetic moment is 0.73μN. The state Z_cs(4220)⁺can be depicted as the compact sta...     

Molecular Nature of X(3872) in B0→ K0X (3872) and B+→ K+X (3872) Decays

We investigate the decays of B⁰→ K⁰X(3872) and B⁺→ K⁺X(3872) based on the picture where the X(3872) resonance is strongly coupled to the ■+ c.c. channel. In addition to the decay mechanism where the X(3872) resonance is formed from the ■ pair hadronization with the short-distance interaction, we have also considered the ■ rescattering diagrams in the long-distance scale, where D and ■ are formed from c and ■ separately. Because of the difference of the...     

Double-heavy tetraquark states with heavy diquark-antiquark symmetry

We calculate the masses of the QQqq(Q=c,b:q=u,d,s)tetraquark states with the aid of heavy diquark-antiquark symmetry(HDAS)and the chromomagnetic interaction(CMI)model.The masses of the highestspin(J=2)tetraquarks that have only the(QQ)(3):(qq)₃.color structure are related with those of conventional hadrons using HDAS.Thereafter,the masses of their partner states are determined with the mass splittings in the CMI model.Our numerical results reveal that(i)the lightest ccnn(n=u,d)is an I(J^P)=0(1⁺)state around 3929 MeV(53 MeV above the DD^* threshold),and none of the double-charm tetraquarks are stable;(ii)the stable double-bottom tetraquarks are the lowest 0(1⁺)bbin around 10488 MeV(≈116 MeV below the BB^*threshold)and the lowest 1/2(1⁺)bbns around 10671 MeV(≈20 MeV below the BB_s^*/B_sB^*threshold);and(iii)the two lowest bcnn tetraquarks,namely the lowest 0(0⁺)around 7167 MeV and the lowest 0(1)around 7223 MeV,are in the nearthreshold states.Moreover,we discuss the constraints on the masses of double-heavy hadrons.Specifically,for the lowest nonstrange tetraquarks,we obtain T_cc<3965 MeV,T_bb<10627 MeV,and T_bc<7199 MeV.     

Exploring hidden-charm and hidden-strange hexaquark states from lattice QCD

Based on five different ensembles of newly generated (2+1)-flavor configurations with pion mass of approximately m_π■(140-310) MeV, we present a lattice analysis of hidden-charm and hidden-strange hexaquarks with the quark content ■. The correlation matrices of two types of operators with J^PC=0⁺⁺, 0^-+, 1⁺⁺ and 1^-- are simulated to extract the masses of the hexaquark candidates, which are subsequently extrapolated to the physical pi...     

关于B0→π－l+ν l衰变过程分支比的计算

通过构造适当的关联函数,计算B→π跃迁形状因子f⁺_Bπ(q²),f _{Bπ(q²)和标量形状因子f⁰(q²),从而就能研究轻子质量对B⁰→π ^{关键词： B介子半轻衰变 形状因子 分支比}}