Improved Light-Cone QCD Sum Rule Analysis of Rare Decays Λb → Λγ and Λb → Λl+l-

We present a systematic light-cone QCD sum rule study of the exclusive rare radiative decay Λ_b → Λ_γ and rare semileptonic decay Λ_b → Λl⁺l^- within the framework of the standard model. Although some light-cone sum rule (LCSR) studies on these rare processes can be found in different literatures, it is necessary to reanalyze them systematically for the reason that either the baryonic distribution amplitudes are improved or different interpolating currents for the Λ_b baryon may lead to quite different results. In addition, the rare process Λ_b → Λ_γ has not yet been analyzed by LCSR with the Ioffe-type current. Taking all these reasons into account, we perform LCSR calculations of both the processes with two types of interpolating currents. Our calculations show that the choice of the interpolating current for the Λ_b baryon can affect the predictions significantly, especially for the rare radiative decay process.     

Double Charm Decays of B Mesons in mSUGRA Model

Based on the low energy effective Hamiltonian with naive factorization, we calculate the branching ratios (BRs) and CP asymmetries (CPAs) for the twenty three double charm decays B/B_s \to D^{(*)}_{(s)} D^{(*)}_{(s)} in both the standard model (SM) and the minimal supergravity (mSUGRA) model. Within the considered parameter space, we find that (a) the theoretical predictions for the BRs, CPAs and the polarization fractions in the SM and the mSUGRA model are all consistent with the currently available data within±2σ errors; (b) For all the considered decays, the supersymmetric contributions in
the mSUGRA model are very small, less than7% numerically. It may be difficult to observe so small SUSY contributions even at LHC.     

Improved analysis of the rare decay processes of Λ_b

It is noted that in the new Particle Data Group(PDG) version the rare decays of the Λ_b baryon have been revised with more accuracy. The new results show that most of the existing theoretical results on the process Λ_b→Λ_γ Lgbare larger than those of experiments. With the improved higher-order light-cone distribution amplitudes of the Λ baryon, we reanalyze the process in the framework of light-cone quantum chromodynamics sum rules and the branching ratio is estimated to be Br (Λ_b→Λ_γ)=(7.38_(-0.39)~(+0.40))×10~(16), which is consistent with the new experimental result. Furthermore, another process Λ_b→Λl~+l~- is also analyzed in the same frame. The final branching ratio is calculated to be Br (Λ_b→Λl~+l~-)=1.20×10~(-6), which is in good accordance with the data from the PDG and other theoretical predictions.     

关于J/ψ辐射衰变产生胶球态的另一种机制

基于粲夸克偶素J/ψ质量大而寿命长的特征的物理内涵和对胶球态产生条件的理解,提出了J/ψ→Gb+γ过程产生胶球态的另一种机制,即认为胶球态Gb来自J/ψ中的组分粲夸克对c_con.(c_con.)分别转变为流粲夸克对c_{cur.(ccur.)时所发射的色八重态胶团对的融合,而余下的流粲夸克对再湮没为光子γ.通过用此模型的计算,讨论了ΓJ/ψ→Gb+γ与有关参数值的关系,并与J/ψ辐射衰变中通过两个末态胶子的强子化产生胶球的机制作出了对比.}     

MCMCINLA Estimation of Missing Data and Its Application to Public Health Development in China in the Post-Epidemic Era

Medical data are often missing during epidemiological surveys and clinical trials. In this paper, we propose the MCMCINLA estimation method to account for missing data. We introduce a new latent class into the spatial lag model (SLM) and use a conditional autoregressive specification (CAR) spatial model-based approach to impute missing values, making the model fit into the integrated nested Laplace approximation (INLA) framework. Combining the advantages of both the Markov chain Monte Carlo (MCMC) and INLA frameworks, the MCMCINLA algorithm is used to implement imputation of the missing data and fit the model to derive estimates of the parameters from the posterior margins. Finally, the economic data and the hemorrhagic fever with renal syndrome (HFRS) disease data of mainland China from 2016–2018 are used as examples to explore the development of public health in China in the post-epidemic era. The results show that compared with expectation maximization (EM) and full information maximum likelihood estimation (FIML), the predicted values of the missing data obtained using our method are closer to the true values, and the spatial distribution of HFRS in China can be inferred from the imputation results with a southern-heavy and northern-light distribution. It can provide some references for the development of public health in China in the post-epidemic era.     

Effects of a Family Non-universal Z' Boson in \bar{B}_d→μ+μ- and B- →π-μ+μ-,ρ-μ+μ- Decays

Motivated by the recently updated experimental measurement on \bar{B}_d→μ⁺μ^- and B^-→π^-μ⁺μ^- decays by CDF and Belle collaborations, we revisit these
decays, as well as B^-→ρ^-μ⁺μ^- decay, within the Standard Model, and evaluate the effects of a family non-universal Z' boson. Under the constraint from {\cal B}(B^-→π^-μ⁺μ^-), we find the ranges of the Z' couplings S^LR_μμ< -5.2×10^-2 or D^LR_μμ < -8.1× 10^-2 are excluded. Within the allowed Z' parameters spaces, comparing with the SM predictions, we find that {\cal B}(\bar{B}_d→ μ⁺μ^-, {\cal B}(B^-→ π^-μ⁺μ^-), and {\cal B}(B^-→ρ^-μ⁺μ^-) could be enhanced by a factor about
226%, 245%, and 254%, respectively, byZ' contributions. However, they are hardly to be reduced. Furthermore, the zero crossing in the normalized forward-backward asymmetry spectrum of B^- →ρ^-μ⁺μ^- decay at low dimuon mass always exists.     

A Phenomenological Analysis of Higher Fock State Contributions to the χCJ Decays

We present a phenomenological analysis of higher Fock state contributions to the χ_CJ decays by using the recent BES experimental data.It is found that the higher Fock state |cc)8g〉 makes an important contribution to the inclusive and exclusive processes with respect to that from the valence Fock state |cc〉 of the χ_CJ and some constraints of these contributions are obtained for the χ_co and χ_c2 states in order to fit the experimental data.     

The Contributions of PGBs in the One-Generation Technicolor Model on the Rare Decays t→cZ,cγ

The Contributions of PGBs in the One-Generation Technicolor Model on the Rare Decays Keeping all masses, we have calculated the contributions of PGBs in the one-generation technicolor model on the rare decays t→cZ, cγ. The branching fractions are B(t→cZ)～10^-7, B(t→cγ)～10^-8 in the most cases. The magnitude of these decays can be significantly enhanced by PGBs.     

Rare Decays B → XS,dνν and XS,d → l+l- in the,Topcolor-Assisted Technicolor Model

We calculate the contributions to the rare decays B → X_S,dνν and X_S,d → l⁺l^- from one-loop Z^o -penguin diagrams in the framework of topcolor-assisted technicolor model. Within the parameter space, we find that: (a) the new contribution from technipions is less than 2% of the standard model prediction; (b) the top-pions can provide a factor of 10 to 30 enhancement to the ratios in question; (c) the topcolor-assisted technicolor model is consistent with the current experimental'data.     

耦合腔阵列与Λ-型三能级原子非局域耦合系统中单光子的传输特性研究

讨论了理想和非理想情况下耦合腔阵列中两个最邻近的腔与Λ-型三能级原子非局域耦合系统中单光子的传输特性.运用准玻色子方法,精确地解出了开放系统中单光子的透射率.Λ-型三能级原子与耦合腔阵列非局域耦合系统具有更多的优点,如:该系统比其他系统调控光子传输特性的可调控参数更多;单光子在该系统中传输的透射谱有三个透射峰.此外,该系统还具有自身的特点,当拉比频率?取值给定之后,改变原子与其中一个腔的耦合强度时,光子的透射谱有一个透射率始终为1的定点,该点对应的光子频率为ω_c-?.在非理想情况下,系统耗散对光子的透射谱有着很大的影响.当只考虑原子耗散时,耗散使得光子透射谱的谷值增大,而峰值不变;当只考虑腔场耗散时,光子透射谱的峰值减小,而谷值不变.另外,随着腔场耗散率和腔的个数的增多,光子透射谱的峰值逐渐减小,但谷值始终不变.对比原子耗散和腔场耗散的情况可以发现,原子耗散使得光子不能被完全反射,而腔场耗散使得光子不能被完全透射.当同时考虑原子和腔场耗散时,光子透射谱谷值的大小不但会受原子耗散率大小的影响,也受腔场耗散率大小的影响,随着腔场耗散率的增大,谷值反而减小;而光子透射谱的峰值始终只受腔场耗散率大小和腔的个数的影响,与原子耗散率取值的大小无关.     

Study on υμ, υγ, Decays and CP Non-Invariance at Early Epoch of the Universe

We study the υ_μ and υ_γ decays in the early epoch of the universe. If m_υγ > 2m_e, there would be a CP asymmetry between υ_γ→e⁺+e^-+υ_e and υ_γ→e⁺+ e^-+ υ_e. The resultant CP non-invariance is a function of temperature and density and can reach l0^-7 for a reasonable temperature range, but it is noticed that if m_υγ > 2υ_μ～200 MeV, the CP non-invariance can be much larger.     

Contribution to Calculation of Ion Microfield Nonuniformity Effect on the Asymmetry of Lyman‐α Line in Dense Plasma

The high orders of Stark effects on spectral line shapes are examined in the ion‐static and electron‐impact ap‐proximations. At first the distribution functions of the spatial derivative of the ion microfield in He⁺ plasma are calculated for different plasma conditions when the coupling parameter is weak. We present new results about the spatial derivative ion microfield distributions and apply them to show the asymmetry of the Lyman‐α (Ly‐α) line in He⁺ plasma. At the second stage we show that asymmetry is affected by the spatial derivative tensor of the local ion electric field. We have used the Monte‐Carlo simulation (MCS) to compute the distribution functions for all tensor components and use them to solve the evolution equation of emitter whose solution serves to compute and therefore to show the line shape asymmetry. Good agreement of our distribution functions of ion microfield gradients and the line asymmetry with other results are obtained (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Decays of excited baryons in the large- N<Subscript>c</Subscript> expansion of QCD

We present the analysis of the decay widths of excited baryons in the framework of the 1/N _c expansion of QCD. These studies are performed up to order 1/N _c and include both positive- and negative-parity excited baryons.     

Study of the production of Λb0 and B0 hadrons in pp collisions and first measurement of the Λb0→J/ψpK- branching fraction

The product of the Λ_b⁰(B⁰) di erential production cross-section and the branching fraction of the decay Λ_b⁰→J/ψpK^- (B⁰→J/ψpK^*(892)⁰) is measured as a function of the beauty hadron transverse momentum, pT, and rapidity, y. The kinematic region of the measurements is p_T <20 GeV/c and 2.0< y< 4.5. The measurements use a data sample corresponding to an integrated luminosity of 3fb^-1 collected by the LHCb detector in pp collisions at centre-of-mass energies √s= 7 TeV in 2011 and √s= 8 TeV in 2012. Based on previous LHCb results of the fragmentation fraction ratio, f_Λb⁰/f_d, the branching fraction of the decay Λ_b⁰→J/ψpK^- is measured to be
B(Λ_b⁰→J/ψpK^-)=(3.17±0.04±0.07±0.34_-0.28^+0.45)×10^-4,
where the rst uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B⁰→J/ψpK^*(892)⁰, and the fourth is due to the knowledge of f_Λb⁰/f_d. The sum of the asymmetries in the production and decay between Λ_b⁰ and Λ_b⁰ is also measured as a function of p_T and y. The previously published branching fraction of Λ_b⁰→J/ψpπ^-, relative to that of Λ_b⁰→J/ψpK^-, is updated. The branching fractions of Λ_b⁰→P_c⁺(→J/ψp)K^- are determined.     

Semileptonic Decays of Heavy Mesons to Light Pseudoscalar Mesons in the BS Formalism

The decay processes from heavy to light pseudoscalar mesons such as π, K, η,η' are studied in a relativistic constituent quark model based on the BS formalism. It is emphasized that the negative energy projector operators's contributions in the BS wavefunctions for light pseudoscalar mesons have to be considered. By taking into account these contributions, the previously encountered difficulties in calculating the decay constants and form factors are found to be removed. A11 the form factors for transitions such as D→π, D→K, D_s→K, D_s→η, D_s→η', B→π, B_s→K are estimated and the branching ratios for these semileptonic decays are calculated. The results of our calculations are consistent with experimental values.     

Application of <Emphasis Type="Italic">T</Emphasis>-Invariance Conditions in Selecting Mechanisms of Nuclear Reactions,Decays, and Fission

T-invariance conditions for the differential cross sections of multiparticle multistep nuclear reactions are found with allowance for spin orientations of particles in the initial channels of such reactions. It is shown that the asymmetry coefficients for different T-parities in the differential cross sections for original and time-reversed reactions are expressed in terms of unified scalar (pseudoscalar) functions that depend of the 3-momenta and spins of particles involved in the initial and final channels of the reactions under analysis. It is also shown that knowledge of the aforementioned functions for the asymmetries under analysis in the original reaction makes it possible to reconstruct the respective functions for the analogous asymmetries in the time-reversed reaction without studying it experimentally. By considering the example of T-even and T-odd asymmetries in reactions where oriented nuclei undergo binary and ternary fission induced by cold polarized neutrons, it is demonstrated that the T-invariance conditions in question can be used to select mechanisms behind the appearance of the above asymmetries—in particular, mechanisms associated with the presence of T-noninvariant interactions.     

icMRCI+Q理论研究CF离子12个-S态和23个?态的光谱性质

采用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV5Z和aug-cc-pV6Z计算了CF~+离子第一离解极限C~+(~2p_u)+F(~2P_u)对应的12个∧-S态(X~l∑~+,a~3∏,1~3∑~+,1~3Δ,1~1∑~-,1~1∑~-,1~3∑~-,2~1∑~+,1~1∏,2~3∏,2~1∏和2~3∑~+)所产生的23个Ω态的势能曲线.计算中考虑了旋轨耦合效应、核价相关和标量相对论修正以及将参考能和相关能分别外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的9个∧-S态和16个Ω态的光谱常数,并且X~1∑~+,a~3∏~(势阱一)∧-S态的光谱常数与已有的实验结果非常符合.此外,计算了CF自由基X~2∏态到CF~+离子束缚和准束缚的9个∧-S态的垂直电离势和绝热电离势,并且CF~+(X~1∑~+)←CF(X~2∏)和CF~+(a~3∏(势阱一))←CF(X~2∏)的垂直电离势和绝热电离势与相应的实验结果也非常符合.由a~3∏,1~1∏态和其他激发∧-S态势能曲线的交叉现象,借助于计算的旋轨耦合矩阵元,分析了a~3∏~(势阱一),1~1∏~(势阱一)和2~1∑~+态的预解离机理.计算的23个Ω态离解极限处的相对能量与实验结果十分吻合.最后计算了(2)0+~(势阱一)(v'=0-5),(1)1~(势阱一)(v'=0-5)和(2)1~(势阱一)(v'=0)到X0~+态跃迁的Franck-Condon因子和辐射寿命.     

The Contribution to Δs and Δg from the Hybrid Components of a proton

The hybrid components of a pro ton can give rise to direct contribution to Δg due to the gluon operator and Δs due to the axial current operator as well. We evaluate such contribution precisely within the framework of the bag model, but the result shows that the contribution is not significant.