Update of g-2 of the muon and △α

We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling,αh(5a)d(MZ2).Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV.     

Photons from Quark and Hadron Phases in Au + Au Collisions

Based on a relativistic hydrodynamic model describing the evolution of the chemically equilibrating quark-gluon plasma system with finite baryon density in a 3＋1-dimensional spacetime, we compute photons from the quark phase, hadronic phase and initial non-thermal contributions. It is found that due to the effects of the initial quark chemical potential, chemical equilibration and rapid expansion of the system, the photon yield of the quark-gluon plasma is strongly suppressed, and photons from hadronic matter and initial non-thermal contributions almost reproduce experimental data.     

Study of the e+ e－ to hadrons via ISR at BABAR

Experimental data from the PEP-II B-factory at 10.6 GeV center-of-mass （c.m.） energy, obtained via initial-state radiation （ISR） with the BABAR detector, are presented. The cross sections for many hadronic processes have been measured from the production threshold to 4-5 GeV of the e^＋e^- c.m. energy. The obtained data allow to study a number of intermediate states and determine the parameters of known resonances and their branching fractions. The exclusive cross section for some number of hadronic sub-processes are presented.     

Electronic Structure and Optical Properties of Semiconducting Orthorhombic BaSi2

Full potential linearized augmented plane wave （FPLAPW） method calculations are carried out for semiconducting orthorhombic BaSi2. The optical properties and the origin of the different optical transitions are investigated. Our calculated band gap of 1.0918eV is indirect, which is in good agreement with the experimental result. The bonds between Ba and Si are considered to be electrovalent bond. The anlsotropy in the imaginary part ε2（w） and real part εl（w） of the optical dielectric tensor are analysed. The contributions of various transition peaks are explained from the imagnary part of the dielectric function.     

Energy Spectrum,g Factors,Strain-Induced Level-Splittings and R-Line Thermal Shift of MgO：V^2＋＋

Traditional ligand-field theory has to be improved by taking into account both pure electronic contribution and electron-phonon interaction one （including lattice-vibrational relaxation energy）. By means of improved ligand-field theory, the R line, t^322T1 and t^322T2 lines, t^22（^3T1）e^4T2, t^22（^3T1）e^4T1 and t2e^2（^4A2）4T1 bands, g factors of t^32 ^4A2 and t32E, four strain-induced level-splittings and R-line thermal shift of MgO：V^2＋ have been calculated. The results are in very good agreement with the experimental data. It is found that for MgO：V^2＋, the contributions due to electronphonon interaction （EPI） come from the first-order term; the contributions from the second-order and higher terms are insignificant. In thermal shift of R line of MgO：V^2＋, the temperature-dependent contribution due to EPI is dominant. The results obtained in this work may be used in theoretical calculations of other effects of EPI.     

ηb decay into charmonium in association with cc pair

We calculate the inclusive decay rates of ηb into charmonium via double c~ pairs for S- and P-wave states ηc, J/ψ and XcJ within the framework of non-relativistic QCD （NRQCD） factorization at leading order in αs. Besides calculating the contributions of the color-singlet channels ηb → cc[2s＋1SL^（1）]＋cc, the effects of cc pair in the color-octet configurations are also considered. We find that ηb → cc[3S1^（8）] ＋cc make a small contribution to Br（ηb →J/ψ（ηc）＋cc）. While in the ηb →XcJ ＋cc case, the color octet contributions are significant, for they are of the same a 5 order as the color-singlet processes. We predict Br（ηb →J/ψ（ηc）＋cc） = 2.99（2.75） × 10^-5 Vc for S-wave states J/ψ and ηc, and Br（ηb → XcJ ＋cc） = （4.37, 3.40, 2.83） × 10^-5 （for J = 0,1, 2） for P-wave states XcJ. In the end, we also find Br（ηb → cccc） is almost saturated by ηb decay into charmonium in association with cc pair from the point of view of duality.     

Hadronic Shower Models in GEANT4： Validation Strategy and Results.

Optimal exploitation of hadronic final states played a key role in successes of all recent hadron collider experiment in HEP,and the ability to use hadronic final states will continue to be one of the decisive issues during the analysis phase of the LHC experinents Monte Carlo implementations of hadronic shower models provided with GEANT4 facilitate the use of hadronic final states,and have been developed for many years.We will give an overview on the physics underlying hadronic shower simulation,discussing the three basic types of modelling;data driven,parametrisation driven,and theory driven modelling,and their respective implementation status in GEANT4.We will confront the different types of modelling with a validation suite for hadronic generators based on cross-sections measurements from thin target experiments,and expose the strength and weaknesses of the individual approaches.     

Hadronic Interpretation of High-Energy Gamma-Rays from Two TeV Sources Coincident with Molecular Clouds Overtaken by Supernova Remnants

We present a possible hadronic explanation of the high-energy γ-ray emission from two very high-energy （VHE） sources, HESS 31745-303 （A ） and HESS 31714-385, which coincide with supernova remnants （SNRs） interacting with dense molecular clouds （MCs）. We calculate the proton spectra and the corresponding hadronic γ-ray spectra for different Mach numbers of the shock wave in a semi-analytical model for the non-linear shock acceleration process, then apply the model to the two newly discovered TeV sources. The results show that the γ-ray spectra for the two sources with energies above 100 MeV detected by HESS and EGRET can be reproduced with low Mach numbers about 2.5. Thus the high-energy γ-ray origin for each one of the two sources can be interpreted as proton-proton （p-p） collisions in MCs overtaken by an SNR shock wave.     

Photoproduction of J/ψ in non-single-diffractive p+p collisions

Significant enhancements of J/ψ production at very low transverse momenta were recently observed by the ALICE and STAR collaborations in peripheral hadronic A+A collisions. The anomalous excess points to coherent photon-nucleus interactions in violent hadronic heavy-ion collisions, which were conventionally studied only in ultra-peripheral collisions. Assuming that the coherent photoproduction is the underlying mechanism responsible for the excess observed in peripheral A+A collisions, its contribution in p+p collisions with nuclear overlap, i.e. nonsingle-diffractive collisions, is of particular interest. In this paper, we perform a calculation of exclusive J/ψ photoproduction in non-single-diffractive p+p collisions at the RHIC and LHC energies based on the pQCD motivated parametrization using the world-wide experimental data, which could be further employed to improve the precision of the phenomenological calculations for photoproduction in A+A collisions. The differential rapidity and transverse momentum distributions of J/ψ from photoproduction are presented. In comparison with the J/ψ production from hadronic interactions, we find that the contribution of photoproduction is negligible.     

Can VMD improve the estimate of the muon g－2?

We show that a VMD based theoretical input allows for a significantly improved accuracy for the hadronic vacuum polarization of the photon which contributes to the theoretical estimate of the muon g-2. We also show that the only experimental piece of information in the τ decay which cannot be accounted for within this VMD framework is the accepted value for Br（τ→ππvτ）, while the T spectum lineshape is in agreement with expectations from e^＋e^- annihilations.     

Relativistic Configuration Interaction Calculations on Kα X-Ray Satellites of Manganese

With contributions from Breit interaction, quantum electrodynarnics （QED） corrections and nuclear mass corrections to the initial and final levels are taken into account. The transition energies, transition probabilities, and absorption oscillator strengths of Kα x-ray from Mn XVII to Mn XXIV have been calculated by using relativistic configuration interaction （RCI） and multi-configuration Dirac Fock （MCDF） method in the active interaction approach. Compared with the only available experimental transition data on He-like and Li-like manganese, the present results are in good agreement with them, and the rest of transition data of the present results are new ones. These wide range data can provide useful parameters for the study of the manganese plasma.     

Non-Thermal Photon Emission from Shell-Type Supernova Remnants

We study the non-thermal photon emission from shell-type supernova remnants （SNRs） in the frame of a two-zone model. In this model, the sites of acceleration, escape and subsequent radiation of particles （both electron and proton） are divided into acceleration and escape zones, respectively. The particle distributions consist of two components, one is produced inside the acceleration zone, the other in the escape zone. We apply this model to two young and one old shell-type SNRs and show that the observed multi-waveband photon spectra for the three SNRs can be explained well in this model and high-energy γ-rays from these SNRs may have hadronic origins.     

Non-spectator Contributions to Lifetime of Λb

In this work, we study the contributions of non-spectator effects to the lifetimes of Λb and B-mesons comparatively. Based on the well-established theoretical framework about the effective weak Lagrangian, we derive the formulation of the non-spectator effects at the quark level. Especially, for Λb we have considered two pictures: the three-valence-quark picture and the quark-diquark picture. In the two pictures, the interference contributions to the total width are different, in this work, we investigate the interference effects in detail. As a preliminary estimate on the lifetimes, we evaluate the hadronic matrix elements appearing in the final formulas of the lifetimes by means of a simple phenomenological model for both pictures. Our results show that the contributions of the non-spectator effects can reduce the ratio of lifetime of Λb to that of B-mesons by 5 ～ 7%. It is noted that in the quark-diquark picture the ratio can be further reduced if excited states of the diquark system are taken into account. We conclude that the measured ratio τ(Λb)/τ(B0)(≈)0.79 [The Data Group, Phys. Rev. D66 (2002) 010001] can be partly understood by the non-spectator effects, although the problem on the discrepancy between theoretical prediction and experimental measurement is not fully solved.     

Study of the rare decay J/ψ→e~+e~-φ

We study the decay process of J/ψ→e~+e~-φ where the relatively clean electromagnetic(EM) transitions appear at leading order at tree level while the hadronic contributions only emerge via hadronic loop transitions. We include the low-lying scalar f_0(980) and pseudoscalar η/η as the dominant contributions in the evaluation of the hadronic loop contributions. It is found that the hadronic effects are negligible compared with the EM contributions.The decay width of J/ψ→e~+e~-φ is determined to be about 2.12 × 10~(-6) ke V if there is no other leading mechanism contributing. This result will be tested by the BESIII experiment with a large J/ψ data sample.     

Non-spectator Contributions to Lifetime of ∧b

In this work, we study the contributions of non-spectator effects to the lifetimes of ∧b and B-mesons comparatively. Based on the well-established theoretical framework about the effective weak Lagrangian, we derive the formulation of the non-spectator effects at the quark level. Especially, for ∧b we have considered two pictures: the three-valence-quark picture and the quark-diquark picture. In the two pictures, the interference contributions to the total width are different, in this work, we investigate the interference effects in detail As a preliminary estimate on the lifetimes, we evaluate the hadronic matrix elements appearing in the final formulas of the lifetimes by means of a simple phenomenological model for both pictures. Our results show that the contributions of the non-spectator effects can reduce the ratio of lifetime of ∧b to that of B-mesons by 5-7％. It is noted that in the quark-diquark picture the ratio can be further reduced if excited states of the diquark system are taken into account. We conclude that the measured ratio τ(∧b)/τ(B^o)-0.79 [The Data Group, Phys. Rev. D66 (2002) 010001] can be partly understood by the non-spectator effects, although the problem on the discrepancy between theoretical prediction and experimental measurement is not fullv solved.     

Exact Calculations of Vertex ^-sγb and ,^-sZb in the Unitary Gauge

In this paper, we present the exact calculations for the vertex ^-sγb and ^sZb in the unitary gauge. We find that （a） the divergent- and μ-dependent terms are left in the effective vertex function Г^γμ（p, k） for b → sγ transition even after we sum up the contributions from four related Feynman diagrams; （b） for an on-shell photon, such terms do not contribute et al.; （c） for off-shell photon, these terms will be canceled when the contributions from both vertex ^sγb and ^sZb are taken into account simultaneously, and therefore the finite and gauge-independent function Zo（xt） = Co（xt） ＋ Do（xt）/4, which governs the semi-leptonic decay b → sl^- l^＋, is derived in the unitary gauge.     

Hadronic light-by-light scattering contribution to the muon g－2

We review recent developments concerning the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. We first discuss why fully off-shell hadronic form factors should be used for the evaluation of this contribution to the g- 2. We then reevaluate the numerically dominant pion-exchange contribution in the framework of large-No QCD, using an off-shell pion-photon-photon form factor which fulfills all QCD short-distance constraints, in particular, a new short-distance constraint on the off-shell form factor at the external vertex in g- 2, which relates the form factor to the quark condensate magnetic susceptibility in QCD. Combined with available evaluations of the other contributions to hadronic light-by-light scattering this leads to the new result αμ^LbyL;had= （116±40） × 10^-11, with a conservative error estimate in view of the many still unsolved problems. Some potential ways for further improvements are briefly discussed as well. For the electron we obtain the new estimate αe^LbyL;had= （3.9± 1.3） × 10^-14.     

Relativistic R-matrix studies of photoionization processes of Ar^5＋

The 3s–np photoionization processes of the ground state 2P1/2 and the metastable state 2P3/2 of Ar5＋ are investigated using our recently developed relativistic R-matrix code, where the interactions between the bound states and the continuum states are included. Both resonance positions and the oscillator strengths are in much better agreement with the absolute experimental measurements by Wang et al.[Wang J C, Lu M, Esteves D, Habibi M, Alna’washi G and Phaneuf R A 2007 Phys. Rev. A 75 062712] with a resolution of 80 meV than their theoretical results. The contributions of the two experimental unresolved transitions are distinguished in our calculations, which show that the transitions from the ground state also make significant contributions to some resonances. Our theoretical results are also in good agreement with the measurements for the first resonance with a higher resolution of 20 meV.     

Two-photon exchange properties in to proton electromagnetic time-like region

The contributions of two-photon exchange in the process e＋ ＋ e-→ p ＋ p including N and △ intermediate states are estimated in a simple hadronic model. The corrections to the unpolarized cross section as well as to the polarized observables Px and Px are evaluated. The results show the corrections to unpolarized cross section are small and the angle dependence becomes weak at small s after considering the N and △（1232） contributions simultaneously, while the correction to Px is enhanced.