Search

The spectrum and relativistic wave functions of $B_c$ system are investigated via solving the complete Salpeter equation. Emphases are put on the study of the partial waves of each $J^P$ state. Our study shows that there are three categories of $J^P$ states. The first category contains $0^-$ and $0^+$ states, which are ${}^1S_0$ dominant state with a small amount of $P$ wave and ${}^3P_0$ dominant state with a small amount of $S$ wave, respectively. The second category includes the natural parity states, such as $1^-$, $2^+$, $3^-$, etc. Taking the $1^-$ state as an example, we study it in two cases. One is the ${}^3S_1$ dominant state with a small amount of $P$ and $D$ waves, and the other is the ${}^3D_1$ dominant state but contains a large amount of $S$ and $P$ wave components. The third category includes the unnatural parity states, such as $1^+$, $2^-$, $3^+$, etc. For the $1^+$ spectrum, the states are grouped into pairs with different radial quantum numbers. Each pair contains two ${}^1P_1-{}^3P_1$ mixing states, and the corresponding mixing angles are calculated by using the relativistic wave functions., Comment: 26 pages, 1 table, 8 figures

In the paper, we calculate the fragmentation functions for $g \to B_c$ and $g \to B_c^*$. The ultraviolet divergences in the calculation are removed through the renormalization of the operator definition of the fragmentation functions under the modified minimal subtraction scheme. We then obtain the fragmentation functions $D_{g \to B_c}(z,\mu_F)$ and $D_{g \to B_c^*}(z,\mu_F)$, which are presented as figures and fitting functions. The obtained fragmentation functions are complementary to the previous work on the next-to-leading order fragmentation functions for $\bar{b}\to B_c(B_c^*)$ and $c\to B_c(B_c^*)$., Comment: 22 pages, 4 figures

Basing on the systems of linear partial differential equations derived from Mellin-Barnes representations and Miller's transformation, we obtain GKZ-hypergeometric systems of one-loop self energy, one-loop triangle, two-loop vacuum, and two-loop sunset diagrams, respectively. The codimension of derived GKZ-hypergeometric system equals the number of independent dimensionless ratios among the external momentum squared and virtual mass squared. Taking GKZ-hypergeometric systems of one-loop self energy, massless one-loop triangle, and two-loop vacuum diagrams as examples, we present in detail how to perform triangulation and how to construct canonical series solutions in the corresponding convergent regions. The series solutions constructed for these hypergeometric systems recover the well known results in literature., Comment: 32 pages, 1 figure

The hypergeometric function method naturally provides the analytic expressions of scalar integrals from concerned Feynman diagrams in some connected regions of independent kinematic variables, also presents the systems of homogeneous linear partial differential equations satisfied by the corresponding scalar integrals. Taking examples of the one-loop $B_{_0}$ and massless $C_{_0}$ functions, as well as the scalar integrals of two-loop vacuum and sunset diagrams, we verify our expressions coinciding with the well-known results of literatures. Based on the multiple hypergeometric functions of independent kinematic variables, the systems of homogeneous linear partial differential equations satisfied by the mentioned scalar integrals are established. Using the calculus of variations, one recognizes the system of linear partial differential equations as stationary conditions of a functional under some given restrictions, which is the cornerstone to perform the continuation of the scalar integrals to whole kinematic domains numerically with the finite element methods. In principle this method can be used to evaluate the scalar integrals of any Feynman diagrams., Comment: 39 pages, including 2 ps figures

By applying the nonrelativistic quantum chromodynamics factorization formalism to hadroproduction, a complete analysis of the polarization parameters , , and for the production is presented at QCD next-to-leading order. With the long-distance matrix elements extracted from experimental data for the production rate and polarization parameter of hadroproduction, our results provide a good description of the measured parameters and in both the helicity and Collins-Soper frames. In our calculations, the frame invariant parameter is consistent in the two frames. Finally, we mention that there are discrepancies between the available experimental data and corresponding theoretical predictions for .

The mass spectra and wave functions for the doubly heavy baryons are computed under the picture that the two heavy quarks inside a doubly heavy baryon, such as two $c$-quarks in $\Xi_{cc}$, combine into a heavy `diquark core' in color anti-triplet firstly, then the diquark core turns into a color-less doubly heavy baryon via combining the light $q$-quark inside the baryon. Namely both of the combinations, the two heavy quarks inside the baryon into a diquark core in color anti-triplet and the heavy diquark core with the light quark into the baryon, are depicted by relativistic Bethe-Salpeter equations (BSEs) with an accordingly QCD inspired kernel respectively, although in the paper only the heavy diquark cores with the quantum numbers $J^P=1^+$ are considered. Since the `second combination' is of the heavy diquark core and the light quark, so the structure effect of the diquark core to the relevant kernel of the BSE is specially considered in terms of the diquark-core wave functions. The mass spectra and wave functions for the `low-laying' doubly heavy baryons in the flavors $(ccq)$, $(bcq)$ and $(bbq)$ and in the quantum numbers $J^P=\frac{1}{2}^+$, $J^P=\frac{3}{2}^+$, achieved by solving the equations under the so-called instantaneous approximation, are presented properly and some comparisons with the others' results under different approaches in the literature are made., Comment: 21 pages, 17 figures; To be published in Chinese Physics C

We present an approach to analyze the scalar integrals of any Feynman diagrams in detail here. This method not only completely recovers some well-known results in the literature, but also produces some brand new results on the $C_{_0}$ function. The approach can be employed to evaluate the coefficient of arbitrary power of $\varepsilon$ in the expansion of a scalar integral, where $D=4-2\varepsilon$ denotes the time-space dimension., Latex, 68 pages

To investigate finite-volume effects on the chiral symmetry restoration and the deconfinement transition and some impacts of possible global topological background for a quantum chromodynamics (QCD) system with $N_f=2$ (two quark flavors), we apply the Polyakov-loop extended Nambu-Jona-Lasinio model by introducing a chiral chemical potential $\mu_5$ artificially. The final numerical results indicate that the introduced chiral chemical potential does not change the critical exponents but shifts the location of critical end point (CEP) significantly; the ratios for the chiral chemical potentials and temperatures at CEP, $\mu_c/\mu_{5c}$ and $T_c/T_{5c}$, are significantly affected by the system size $R$. The behavior is that $T_c$ increases slowly with $\mu_5$ when $R$ is large and $T_c$ decreases first and then increases with $\mu_5$ when $R$ is small. It is also found that for a fixed $\mu_5$, there is a $R_{\text{min}}$, where the critical end point vanishes, and the whole phase diagram becomes a crossover when $R, Comment: 8 pages

The electromagnetic decay contributions to J/ psi(psi') -> VP, where V and P stand for vector and pseudoscalar meson, respectively, are investigated in a vector meson dominance (VMD) model. We show that J/psi(psi) -> gamma* -> VP can be constrained well with the available experimental information. We find that this process has significant contributions in psi' -> VP and may play a key role in understanding the deviations from the so-called "12% rule" for the branching ratio fractions between psi -> VP and J/psi -> VP. We also address that the "12% rule" becomes very empirical in exclusive hadronic decay channels. (c) 2006 Elsevier B.V. All rights reserved.

We present a quantitative analysis of the D-sJ(+) (2632) observed by SELEX mainly focusing on the assumption that D-sJ(+) (2632) is the first radial excitation of the 1(-) ground state D-s(*)(2112). By solving the instantaneous Bethe-Salpeter equation, we obtain the mass 2658 +/- 15 MeV for the first excited state, which is about 26 MeV heavier than the experimental value 2632 +/- 1.7 MeV. By means of PCAC and low-energy theorem we calculate the transition matrix elements and obtain the decay widths: Gamma(D-sJ(+) -> D(s)(+)eta) = 4.07 +/- 0.34 MeV, Gamma(D-sJ(+), (DK+)-K-0) similar or equal to Gamma(Gamma(D-sJ(+) -> (D+K0)) = 8.9 +/- 1.2 MeV, and the ratio Gamma(D-sJ(+) -> (DK+)-K-0)/Gamma(D-sJ(+) -> D(s)(+)eta) = 2.2 +/- 0.2 as well. This ratio is quite different from the SELEX data 0.14 +/- 0.06. The summed decay width of those three channels is approximately 21.7 MeV, already larger than the observed bound for the full width (

Three new observables for Z-factory to measure the weak dipole moment of $\tau$ lepton ($d_w^\tau$) are proposed. As those observables employed at LEP-I, the new observables depend on the real and imaginary parts of $d_w^\tau$ linearly, thus we calculate the slopes, i.e. the linear coefficients of the dependence, precisely and find that the obtained slopes are much lager than those employed at LEP-I. It means that the signal for the weak dipole moment $d_w^\tau$ may be enhanced quite a lot, if one employs the new observables. Being superior to those at LEP-I, we recommend measuring the weak dipole moment $d_w^\tau$ in terms of the new observables if re-analyzing the data of LEP-I or doing the measurement at a possible Z-factory in the near future.

The possible transverse polarization of the $\tau$-lepton, which is $T$-odd and can be used to measure CP-violation, is estimated precisely in the radiative decay mode $B_c \to \tau \bar \nu_\tau \gamma$ with possible parameters for the multi Higgs doublet model and the R-parity violating supersymmetric model. We find that the up-bound of the transverse polarization with possible parameters in the models is at very different levels i.e. it can be $\leq 15\sim 23%$ for the former but $\leq 0.1 %$ for the latter, and it is accessible experimentally soon.

We precisely derive the mass squared matrices for charged and neutral (CP-odd and CP-even) Higgs, as well as the mass matrices for neutrino-neutralino and charged lepton-chargino in the minimal R-parity violating supersymmetry with local U(1)(B-L) symmetry. In the framework the nonzero TeV scale vacuum expectations of right-handed sneutrinos induce the heavy mass of neutral U(1)(B-L) gauge bosons and result in relatively large mixing between the lightest CP-even Higgs and the right-handed sneutrinos when we include the one-loop corrections to the scalar potential. We numerically show that there is parameter space of the considered model to accommodate experimental data on the new ones of Higgs signal from the LHC and experimental observations on the neutrino oscillation simultaneously.

The color-octet proposition of J/psi(psi') production and its consequences are outlined. To confirm the proposition, the signature of the color-octet production to the electroweak production 'background' in e(+)e(-) collision is discussed. It is pointed out that the electroweak production in e(+)e(-) collision itself is interesting, and a thorough experimental investigation on it should be carried out soon.

Within the framework of QED we investigate inclusive J/psi production at e(+)e(-) colliders. It is expected to be a further test to charmonium production mechanisms and QED. We find that at the energies of CESR, BEPC, and KEK TRISTAN (e.g., 4.0 GeV less than or equal to root s less than or equal to 60 GeV), the contributions of the concerned electromagnetic processes to J/psi inclusive production are great, even dominant; thus, they greatly affect the observation of the color-octet J/psi, production signature at e(+)e(-) colliders. The production of psi', being similar to that of J/psi's, is roughly estimated, and its influence on the observation of the color-octet J/psi production signature in e(+)e(-) collisions is also discussed. [S0556-2821(98)04805-X].

The complete QCD corrections to the scalar top quark pair production via $\gamma \gamma$ fusion in parent $e^{+}e^{-}$ collider are calculated in the Supersymmetric Model. The various origins of corrections are discussed. We find that the correction due to gluino exchange is smaller than that due to conventional gluonic contribution, and the contribution due to squark quartic interactions is much smaller. Moreover, the dependences of the corrections on the masses and the mixing angle of the supersymmetric particles are also investigated., Comment: 25 Pages, LaTex, 10 eps figures.

$J/\ensuremath{\psi}$ production associated with a hard photon in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation, being of a QED nature, is investigated thoroughly in this paper. To show its influence on the observation of the color-octet signature in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation via $J/\ensuremath{\psi}$ inclusive production, the cross sections of $J/\ensuremath{\psi}$ production through different mechanisms at various energies are compared quantitatively by presenting them in figures together. The contribution from the production associated with a hard photon to the inclusive production of $J/\ensuremath{\psi}$ is pointed out to be significant at the concerned energies; thus, the influence of it on the observation of the color-octet signature should be dealt with carefully.

A scheme, the so-called {open_quote}{open_quote}projection,{close_quote}{close_quote} for handling singularities in processes such as {ital e}{sup +}{ital e}{sup {minus}}{r_arrow}{ital t{bar b}e{sup {minus}}}{bar {nu}} (or {ital e}{sup +}{ital e}{sup {minus}}{r_arrow}{ital u{bar d}e{sup {minus}}}{bar {nu}}) is proposed. In the scheme, with the help of gauge invariance, the large power quantities ({ital s}/{ital m}{sup 2}{sub {ital e}}){sup {ital n}} ({ital n}{ge}1;{ital s}{r_arrow}{infinity}) are removed from the calculation totally, while in the usual schemes the large quantities appear and only will be canceled at last. The advantages of the scheme in numerical calculations are obvious; thus, we focus our discussions mainly on the advantages of the scheme in the special case where the absorptive part for some propagators relevant to the process could not be ignored, and a not satisfactory but widely adopted approximation is made; i.e., a finite constant {open_quote}{open_quote}width{close_quote}{close_quote} is introduced to approximate the absorptive part of the propagators phenomenologically even though QED gauge invariance is violated. {copyright} {ital 1996 The American Physical Society.}

A comparative study of the full ${\ensuremath{\alpha}}_{s}^{4}$ perturbative QCD calculation of the hadronic production of the ${B}_{c}$ and ${B}_{c}^{*}$ mesons and the fragmentation approximation is presented. We examined the various subprocesses in detail and the distribution $C(z)$, where $z$ is twice the fraction of the ${B}_{c}$ or ${B}_{c}^{*}$ meson energy in the center of mass of the subprocess, which proved insightful and revealed the importance of certain nonfragmentation contributions. We concluded that the condition for the applicability of the fragmentation approximation in hadronic collisions is that the transverse momentum ${P}_{T}$ of the produced ${B}_{c}$ and ${B}_{c}^{*}$ be much larger than the mass of the ${B}_{c}$ meson: i.e., ${P}_{T}\ensuremath{\gg}{M}_{{B}_{c}}$. Numerical results for the cross sections at the Fermilab Tevatron are also presented using updated parton distribution functions with various kinematic cuts.

Having taken the QED radiative correction and one-loop weak corrections into account, we have computed the unpolarized forward-backward asymmetry in the process $e^+e^- -> \mu^+\mu^-$ at a very reasonable accuracy. Special attention to the effects around the LEP 200 energy, induced by the possible $Z'$ boson of the left-right symmetric model $SU(2)_{L} \times SU(2)_{R} \times U(1)_{B-L}$, is paid. The numerical results of the directly measurable asymmetry $A_{FB}^{\mu}$ versus the CMS energies are presented in figures. One may be convinced by the results that precise measurements on the asymmetry in future colliders will possibly present some indirectly evidence of the $Z'$ boson.

Keeping all the terms of heavy flavor masses up to the leading order, and bearing in mind that (i) the massive top m t ⩾ 100 GeV, (ii) the possible energies: S=200 GeV at LEP-II and a higher one S=500 GeV , we carry out precise calculations on the single top-quark production e + +e - → t + c ( t +c) in the framework of the minimal Standard Model (MSM) and its extensions (of four generations and one or two Higgs doublets), to see the possible sense of the single-top production for the colliders. The results show that the process is unmeasurably small for both the MSM and the extension with four generations of fermions but only one Higgs doublet; however, it is possibly measurable for the extensions with two Higgs doublets and particularly favorable parameter values even at LEP-II.

Based on the QCD inspired potential model, the production of the Bc or B c meson and their corresponding excited states respectively, accompanied by two heavy quark jets in the decay of the boson Z0, is computed. The results show that the production is significant and the experimental study on the Bc and B c mesons becomes accessible soon.

Natural Science Foundation Project of CQ CSTC[2008BB0298]; Natural Science Foundation of China[10805082, 10875155]; Chinese Academy of Engineering Physics[2008T0401, 2008T0402]

We investigate the J/psi polarization in photoproduction at the Hadron Electron Ring Accelerator(HERA) up to the next-to-leading order of QCD. The results show that the transverse momentum p_t and energy fraction z distributions of J/psi production do not agree with the observed ones very well. The theoretical uncertainties for the z distributions of the J/psi polarization parameters with respect to various choices of the renormalization and factorization scales are too large to give an accurate prediction. The uncertainties for the p_t distributions of these parameters are small when p_t>3GeV and the obtained p_t distributions can not describe the experimental data even in this region., Comment: 5 pages, 3 figures. Discussion on the theoretical uncertainties from the choice of renormalization scale was added

Starting from the operator formalism, Ward identities are derived for W3 conformal field theories on a torus. The action of the zero mode of the spin-three field inside correlation functions is discussed.

The production of (bc)-quarkonium (B{sub c} meson and its excited states) or (cb)-quarkonium (B{sub c} meson and its excited states) via top quark t or top antiquark t decays, t{yields}(bc)+c+W{sup +} or t{yields}(cb)+c+W{sup -}, respectively, is studied within the framework of NRQCD. In addition to the production of the two color-singlet S-wave states |(bc)({sup 1}S{sub 0}){sub 1}> or |(cb)({sup 1}S{sub 0}){sub 1}> and |(bc)({sup 3}S{sub 1}){sub 1}> or |(cb)({sup 3}S{sub 1}){sub 1}>, the production of the P-wave excited (bc) or (cb) states, i.e. the four color-singlet P-wave states |(bc)({sup 1}P{sub 1}){sub 1}> or |(cb)({sup 1}P{sub 1}){sub 1}>, and (bc)({sup 3}P{sub J}){sub 1}> or (cb)({sup 3}P{sub J}){sub 1}> (with J=(1,2,3)), is also studied. According to the velocity scaling rule of NRQCD, for the production of P-wave excited states the contributions from the two color-octet components |(bc)({sup 1}S{sub 0}){sub 8}> or |(cb)({sup 1}S{sub 0}){sub 8}> and |(bc)({sup 3}S{sub 1}){sub 8}> or |(cb)({sup 3}S{sub 1}){sub 8}> are also taken into account. We quantitatively discuss the possibility and the advantages in experimental studies of B{sub c} or B{sub c} meson and its excited states via the indirect production at LHC in high luminosity runs and at LHC possible upgraded versions such as SLHC, DLHC,more » TLHC, etc. in the future.« less

The effects of the intrinsic charm on the hadronic production of $\Xi_{cc}$ are studied. By taking reasonable intrinsic charm component into account, the change of the theoretical prediction on the production of $\Xi_{cc}$ for LHC and Tevatron is small, but in contrast it may enhance significantly for SELEX. The reason is that the collision energy at LHC and Tevatron is so large that the gluon-gluon fusion sub-process, which is irrelevant to intrinsic charm, becomes dominant. But the situation for SELEX is quite different. Our numerical results for SELEX show that by considering all the contributions from various sub-processes, the predicted cross-section may be enhanced by a factor so big as $10^2$ due to a modulating intrinsic charm being taken into account. Therefore, the hadronic production of $\Xi_{cc}$ at SELEX may be sensitive enough in observing the intrinsic charm inside the incident hadrons., Comment: 18 pages, 8 figures. More discussions are added

To try to understand the experimental observation of SELEX Collaboration and to check the existent results in literature, we have done a theoretical investigation on hadronic production of the doubly charmed baryon Xi(cc) (Xi(++)(cc) or Xi(+)(cc)) under the general-mass variable-flavor-number (GM-VFN) scheme. A similar study of the production at LHC and TEVATRON is also performed. The production here is realized via production of a binding diquark either (cc)[S-3(1)]((3) over bar) (in configuration S-wave and in color (3) over bar) or (cc)[S-1(0)](6) (in configuration S-wave and in color 6) instead of only the diquark (cc)[S-3(1)]((3) over bar) is considered. Numerical results show that the production via each configuration of the diquark is comparable at LHC and TEVATRON under the condition that the NRQCD matrix elements relevant to the diquark production are assumed approximately to be equal to each other; and the contributions from collision of a so-called "extrinsic" charm and a gluon inside the colliding hadrons are comparable with, or even greater than, those from the so-called gluon-gluon fusion, especially, in the region of small transverse-momentum p(t). We also note that due to the contributions from the "extrinsic" charm, the theoretical prediction on the production of the baryon Xi(cc) is raised by one order in comparison with the existent predictions almost.

Studies on the decay and production of $B_c (B^*_c)$ meson are briefly reviewed. Considering RUN-II of Tevatron and the schedule of LHC, the theoretical studies of $B_c$ meson will jump to a new stage not only for itself but also to implement the studies of the heavy quarkonia etc., 8 pages, 2 figures

The contributions from the color-octet components |(c (b) over bar)(8)(S-1(0))g > and |(c (b) over bar)(8)(S-3(1))g > to the h(Bc) or chi(Bc)(J) (the P-wave B-c meson) hadroproduction are estimated in terms of the complete O(alpha(s)(4)) calculation. As necessary inputs in the estimate, we take the values of the octet matrix elements according to the nonrelativistic quantum chromodynamics scaling rules, and as a result, we have found that the contributions to the P-wave production may be the same in order of magnitude as those from the color-singlet ones, |(c (b) over bar)(1)(P-1(1))> and |(c (b) over bar)(1)(P-3(J))> (J=1,2,3). Especially, our result indicates that the observation of the color-octet contributions to the P-wave production in the low transverse momentum region is not very far from the present experimental capability at Tevatron and LHC.

Adopting the complete alpha(s)(4) approach of the perturbative QCD and the updated parton distribution functions, we have estimated the hadronic production of the P-wave excited B-c states (B-cJ,B-L=1*). In the estimate, special care has been paid to the dependence of the production amplitude on the derivative of the wave function at origin which is obtained by the potential model. For experimental references, main theoretical uncertainties are discussed, and the total cross section as well as the distributions of the production with reasonable cuts at the energies of Tevatron and CERN LHC are computed and presented properly. The results show that the P-wave production may contribute to the B-c-meson production indirectly by a factor of about 0.5 of the direct production, and according to the estimated cross section, it is further worthwhile to study the possibility of observing the P-wave production itself experimentally.

The annihilation of the B-c meson to leptons and inclusive light hadrons is analyzed in the framework of nonrelativistic QCD (NRQCD) factorization. We find that the decay mode, which escapes from the helicity suppression, contributes a sizable fraction width. The branching ratio due to the contributions from the color-singlet component of the B-c meson can be of the order of 10(-2). The contributions from the color-octet components are estimated. With the consideration of the NRQCD velocity scaling rule, we find that the color-octet contributions are sizable too, especially in a certain phase space of the annihilation. They are greater than (or comparable to) those from the color-singlet component. A few observables on the spectrum of charged leptons (e, mu) relevant to the contributions are suggested that may be used as measurements of the evidence of the color-octet components in future B-c experiments. A kind of typical "long-distance contributions'' in the annihilation is also estimated.

The quark recombination mechanism is proposed to explain the asymmetry between production rates of $D^+$ and of $D^-$ in their inclusive productions, and also asymmetries for other charmed hadrons. These asymmetries are observed in experiment and are called as leading particle effects. In this work we give a general analysis for contributions of quark recombination to these asymmetries. The contributions consist of a perturbative- and nonperturbative part. We perform two types of factorization by considering the produced hadron with large transverse momentum and by taking charm quark as a heavy quark, respectively. In the case of large transverse momentum the effect of quark recombination is the standard twist-4 effect. We find that the contributions are parameterized with four nonperturbative functions, defined with four quark operators at twist-4, for initial hadrons without polarization. By taking charm quark as a heavy quark the factorization can be performed with the heavy quark effective theory(HQET). The effect of quark recombination is in general parameterized by eight nonperturbative parameters which are defined as integrals with matrix elements of four quark operators defined in HQET. For unpolarized hadrons in the initial state, the parameters can effectively be reduced to four. Perturbative parts in the two types of factorization are calculated at tree-level., Comment: Change to Revtex format, minor changes in text

A method for obtaining the low chemical potential dependence of the dressed quark propagator from an effective quark-quark interaction model is developed. From this the chemical potential dependence of the chiral quark condensate and bag constant are evaluated. It is found that the chiral order parameter decreases with the increasing chemical potential $\mu$, which is qualitatively different from the results given by some authors in the literature. The reason for this discrepancy is discussed., Comment: 11 pages, 4 figures

The decays of the meson B-c to a P-wave charmonium state chi(c) or h(c) (here chi(c) and h(c) denote (c (c) over bar[P-3(J)]) and (c (c) over bar[P-1(1)]), respectively); the semileptonic ones B-c --> chi(c)(h(c))+l+ nu(l), and the two-body nonleptonic ones B-c -->chi(c) (h(c)) + h (h indicates a meson) are computed. To properly deal with the recoil effects, which may be relativistic in the decays, in the computation the framework of a heavy quark model, which is based on the Bethe-Salpeter equation and QCD inspired potential, is adopted. We find that all the decay rates are quite sizable and under reasonable approximations, all of the form factors occurring in the decays can be formulated precisely by means of proper kinematics factors and two independent overlapping integrations of the wave functions. As a result, the decays will be accessible at the CERN Large Hadron Collider and in run II at the Fermilab Tevatron in the foreseeable future. In particular, the cascade decays, i.e., B-c --> chi(c)[P-3(1,2)]+l+nu(1)(B-c -->chi(c)[P-3(1,2)]+h) and chi(c)[P-3(1,2)] --> J/psi+gamma, being followed accordingly, may affect the observations of the B-c meson through the decays B-c-->J/psi+l + nu(l) (B-c-->J/psi+h) substantially, and the decays B-c-->h(c)+... may be used as a fresh window experimentally to observe the h(c) state potentially.

The lifetime of the B-c meson is estimated by means of consistent considerations of all of the heavy mesons (B-0,B+/-,B-s,D-0,D',D-s) and the double heavy meson B-c itself as well. The framework, where the nonspectator effects for inclusive decays in terms of the optical theorem are taken into account properly, is adopted, and the parameters appearing in the estimate are treated phenomenologically by global fitting all the existing data for all the heavy mesons. In this estimation, special attention is paid to the masses of the heavy flavors and the bound-state effects as well. The present approach to the problem is meaningful because the numerical results show that the lifetime of the meson B-c can reach to the center value of the experimental observation. Because of the interference between the terms of the QCD correction from penguin diagrams and the main ones c(1)O(1), c(2)O(2), the total width of the meson B-c is enhanced by a factor about 3-4% that is different from the other heavy mesons and can be tested experimentally in the future.

It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model. Gluon dressing of the axial vector vertex and the quark self-energy functions is described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger-Dyson equation in the rainbow approximation, respectively., Comment: 10 pages

The one-loop radiative corrections to the pure leptonic decay ${B}_{c}\ensuremath{\rightarrow}l{\ensuremath{\nu}}_{l}$ are presented. We treat the infrared divergences appearing in the loop calculations together with those in the radiative decay ${B}_{c}\ensuremath{\rightarrow}l{\ensuremath{\nu}}_{l}\ensuremath{\gamma}.$ The divergences are finally canceled by each other to make the results finite. It is emphasized that the radiative decay may be separated properly from the pure leptonic decays. We can compare our results with the experimental measurements directly as long as the theoretical ``softness'' of the photon corresponds to the experimental resolutions. Furthermore with the nonrelativistic constituent quark model, the typical long distance contributions to the radiative decays are estimated, and it is shown that the contributions are negligible in comparison with the accuracy of one-loop corrections and the expected experimental measurements.

Based on the quark propagator in the instanton dilute liquid approximation, we calculate analytically the quark condensate $$, the mixed quark gluon condensate $g_{s}$ and the four quark condensate $$ at the mean field level in the framework of global color symmetry model. The numerical calculation shows that the values of these condensates are compatible with the ranges determined by other nonperturbative approaches. Moreover, we find that for nonlocal four quark condensate the previous vacuum saturation assumption is not a good approximation even at the mean field level., Comment: 8 latex pages, no figure, Submitted to Phys. Rev. C

To the leading order, the radiative leptonic decays $B_c \to \gamma \ell \bar \nu$ ($ \ell=e, \mu$) are studied carefully. In the study, a non-relativistic constituent quark model and the effective Lagrangian for the heavy flavour decays are used. As a result, the branching ratios turn out to be of the orders of $10^{-5}$ for $B_c \to \gamma \mu \bar \nu $ or for $B_c \to \gamma e \bar \nu $. Based on this study, we point out the decays being accessible experimentally at the future LHC, and the possibility to determine the decay constant $f_{B_c}$ through the radiative decays., Comment: 9 pages Latex, including 2 figures

We re-calculate the exclusive semileptonic and nonleptonic decays of $B_c$ meson to a $P$-wave charmonium in terms of the improved Bethe-Salpeter (B-S) approach, which is developed recently. Here the widths for the exclusive semileptonic and nonleptonic decays, the form factors, and the charged lepton spectrums for the semileptonic decays are precisely calculated. To test the concerned approach by comparing with experimental measurements when the experimental data are available, and to have comparisons with the other approaches the results obtained by the approach and those by some approaches else as well as the original B-S approach, which appeared in literature, are comparatively presented and discussed.

We introduce a parametrization scheme for $J/\psi(\psi^\prime)\to VP$ where the effects of SU(3) flavor symmetry breaking and doubly OZI-rule violation (DOZI) can be parametrized by certain parameters with explicit physical interpretations. This scheme can be used to clarify the glueball-$q\bar{q}$ mixing within the pseudoscalar mesons. We also include the contributions from the electromagnetic (EM) decays of $J/\psi$ and $\psi^\prime$ via $J/\psi(\psi^\prime)\to \gamma^*\to VP$. Via study of the isospin violated channels, such as $J/\psi(\psi^\prime)\to \rho\eta$, $\rho\eta^\prime$, $\omega\pi^0$ and $\phi\pi^0$, reasonable constraints on the EM decay contributions are obtained. With the up-to-date experimental data for $J/\psi(\psi^\prime)\to VP$, $J/\psi(\psi^\prime)\to \gamma P$ and $P\to \gamma\gamma$, etc, we arrive at a consistent description of the mentioned processes with a minimal set of parameters. As a consequence, we find that there exists an overall suppression of the $\psi^\prime\to 3g$ form factors, which sheds some light on the long-standing "$\rho\pi$ puzzle". By determining the glueball components inside the pseudoscalar $\eta$ and $\eta^\prime$ in three different glueball-$q\bar{q}$ mixing schemes, we deduce that the lowest pseudoscalar glueball, if exists, has rather small $q\bar{q}$ component, and it makes the $\eta(1405)$ a preferable candidate for $0^{-+}$ glueball.

We have used our measurements of final states from e+e− containing an isolated muon and a hadronic or electron shower to search for new spin 0 charged particles. We exclude (95% CL) a supersymmetric partner of the τ with a mass less than 14 GeV/c2. We obtain upper limits on the branching ratio to τvτ for charged Higgs particles or technipions with masses up to 14 GeV/c2. This disagrees with some technicolor model predictions.

PETRA, the e+e− collider, has operated at a maximum CM energy of 46.78 GeV. We update our previous results on new particle searches and set significantly better mass limits on some.

We study the production of single γ, e and μ at high πt using the high energy data of the Mark-J detector at PETRA. We find good agreement with QED. We give mass limits of the SUSY particles γ , v , e and W studying the associated production of W and ẽ and radiative production of pairs of γ or v in three-body reactions.

In the SU L (2) ⊗ SU R (2) ⊗ U B − L (1) model, an accessible heavy neutral lepton may exist owing to the mixing of generations. Based on a rough estimate, it is pointed out that the most hopeful experiments to observe this lepton are ν -production in an emulsion (because the track of a particle with lifetime 10 −11 −10 −13 s could be seen) and e-production.

The strong interaction coupling constant αs has been measured with a new method, the planar triple energy correlation in the reaction e+e- → hadrons at center-of-mass energies ranging from 14 GeV to 46.78 GeV. A complete second-order perturbative QCD calculation was used. ΛMS = 110 ± 30 −55+70 MeV is found.

A study of τ-lepton production in the CMS energy region from 14 to 46.8 GeV at PETRA is reported. The cross section, the decay branching ratio into μν ν , and the electroweak parameters are determined with a total integrated luminosity of 115 pb −1 .

The process D+s→f0π+ is calculated in terms of the bag model and by fitting the new data it is probably the best way to determine the (s s ) component of f0(975).

We investigate the effects of including fermion masses in calculating the W pair polarization density matrix for the process qq → W + W − , and in testing the neutral scalar and vector boson couplings to W + W − at hadron colliders. Appreciable effects are found at SSC energy and, in some cases, at Tevatron energy as well.