Search

In this paper we take B-L supersymmetric standard model (B-LSSM) and TeV scale left-right symmetric model (LRSM) as two representations of the two kinds of new physics models to study the nuclear neutrinoless double beta decays ($0\nu2\beta$) so as to see the senses onto these two kinds of models when the decays are taken into account additionally. Within the parameter spaces allowed by all the exist experimental data, the decay half-life of the nucleus $^{76}$Ge and $^{136}$Xe, $T^{0\nu}_{1/2}$($^{76}$Ge, $^{136}$Xe), is precisely calculated and the results are presented properly. Based on the numerical results, we conclude that the room of LRSM type models for the foreseeable future experimental observations on the decays is greater than that of B-LSSM type models., Comment: 37 pages, 9 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 .

We take ($\mu^\pm e^\mp$) systems and consider the states with quantum number $J^P=0^-$ as examples, to explore the different contents of the instantaneous Bethe-Salpeter (BS) equation and its analog, Breit equation, by solving them exactly. The results show that the two equations are not equivalent, although they are analogous. Furthermore, we point out that the Breit equation contains extra un-physical solutions, so it should be abandoned if one wishes to have an accurate description of the bound states for the instantaneous interacting binding systems.

We try to apply a constituent quark model (a variety chiral constituent quark model) and the resonating group approach for the multi-quark problems to compute the effective potential between the $N\bar{N}$ in $S$-wave (the quarks in the nucleons $N$ and $\bar{N}$, and the two nucleons relatively as well, are in $S$ wave) so as to see the possibility if there may be a tight bound state of six quarks as indicated by a strong enhancement at threshold of $p\bar{p}$ in $J/\psi$ and B decays. The effective potential which we obtain in terms of the model and approach shows if the experimental enhancement is really caused by a tight $S$-wave bound state of six quarks, then the quantum number of the bound state is very likely to be $I=1, J^{PC}=0^{-+}$., Comment: 8 pages, 9 figures

We present an approach to solve a Bethe-Salpeter (BS) equation exactly without any approximation if the kernel of the BS equation exactly is instantaneous, and take positronium as an example to illustrate the general features of the solutions. As a middle stage, a set of coupled and self-consistent integration equations for a few scalar functions can be equivalently derived from the BS equation always, which are solvable accurately. For positronium, precise corrections to those of the Schr\"odinger equation in order $v$ (relative velocity) in eigenfunctions, in order $v^2$ in eigenvalues, and the possible mixing, such as that between $S$ ($P$) and $D$ ($F$) components in $J^{PC}=1^{--}$ ($J^{PC}=2^{++}$) states as well, are determined quantitatively. Moreover, we also point out that there is a problematic step in the classical derivation which was proposed first by E.E. Salpeter. Finally, we emphasize that for the effective theories (such as NRQED and NRQCD etc) we should pay great attention on the corrections indicated by the exact solutions., Comment: 4 pages, replace for shortening the manuscript

Since long-lived light bottom squark (sbottom) and its anti-particle with a mass close to the bottom quark have not been excluded by experiments so far, we consider such a sbottom to combine with its anti-particle to form a color singlet meson-like bound state or to combine with a common anti-quark to form a fermion-like one, or accordingly their anti-particles to form an anti-particle bound system. Namely we calculate the low-lying spectrum of the systems based on QCD inspired potential model. To be as relativistic as possible, we start with the framework of Bethe-Salpeter (BS) equation even for non-relativistic binding systems. Finally, we obtain the requested spectrum by constructing general forms of the BS wave functions and solving the BS equations under instantaneous approximation.

We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagator from an effective quark-quark interaction model. Within this approach we explore the chemical potential dependence of the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinement order parameters. A comparison with the results of previous researches is given.

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.

The semileptonic decays of meson $B_c$ to a P-wave charmonium state $\chi_c(^3P_J)$ or $h_c(^1P_1)$ are computed. The results show that the decays are sizable so they are accessible in Tevatron and in LHC, especially, with the detectors LHCB and BTeV in the foreseeable future, and of them, the one to the $^1P_1$ charmonium state potentially offers us a novel window to see the unconfirmed $h_c$ particle. In addition, it is pointed out that since the two charmonium radiative decays $\chi_c(^3P_{1,2}) \to J/\psi+\gamma$ have sizable branching ratios, the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of the observing the $B_c$ meson through the semileptonic decays $B_{c}\to {J/\psi}+{l}+\nu_{l}$ substantially.

Based on a modification of the global color symmetry model, we have calculated the four-quark condensate [: (q) over bar gamma mu lambdaC degrees /2 q(q) over bar gamma mu lambdaC degrees /2 q :] beyond vacuum saturation approximation by including the contribution of pi and sigma masons. The numerical results show that there is a sizeable correction of the four-quark condensate in comparison with its factorized value using the vacuum saturation approximation.

It is shown that the effective gluon propagator in the global color symmetry model can be calculated in the instanton dilute liquid approximation. The calculated effective gluon propagator is consistent with the general command on the qualitative features of the gluon propagator, i.e., (i) the gluon propagator is significantly enhanced at small space-like k(2), and (ii) for k(2) > 1.5 GeV2 the perturbative results are quantitatively reliable.

With the fresh experimental bounds of b → sγ issued by CLEO and the value of the top-quark mass by CDF and D0, the constraints on the two Higgs doublet models (2HDM) are re-examined. In the examination an effective Lagrangian is used, which contains all of the energy scale evolution not only from the W boson mass to the bottom-quark mass but also from the top-quark mass to W boson mass for the QCD corrections. As a result, it is implied that the constraint on the mass of the charged Higgs boson emerging in the concerned models turns to be more stringent than that achieved by the earlier analyses.

We study possible observational effects of the two Higgs doublets in the e(+)e(-), at the LEP II energy. We have found that the observational values can be obviously different from those predicted by the minimal standard model (MSM), but the results depend on the parameters of the extended model. The possibilities of the observation are discussed in some details.

The effects of CP asymmetry in top-pair production with polarized photon beam collisions, which may arise in two Higgs doublet extensions of the minimal standard model, are studied. Some of the advantages to observe the CP non-invariance in the production are pointed out. The CP asymmetry will be enhanced by polarized photon fusion greatly compared to the unpolarized one and the signal can reach so high up to a few percents.

In this work, the light JPC = 0++ mesons f0(975), a0(980) and S*(980) are interpreted as the usual states, their masses are investigated in the framework of the QCD sum rules.

We re-evaluated the decay up to one-loop order of electroweak corrections in standard model with the nowadays parameters, determined by the best measurements including the latest ones from LEP and SLC. Within error range of the CDF measurement of top-quark; mass, the electroweak correction reduces the decay width less than 0.7% and the correction value varies in the range of 0.5%.

In order to have a reliable calculation on a transition between two double heavy mesons and bearing a sizable recoil, a generalized "instantaneous approximation" is emphasized and the way how to make the approximation is described in this paper. The reliability and limitation of the approach are discussed. Prospect on its potential applications is outlined also.

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.

Virtual effects of supersymmetry on the flavor changing process at LEPII are calculated in the minimal supersymmetric standard model (MSSM). We analyze the cross section of , and find that even for the most distinguishable mode , the effect is small compared with the SM expectation.

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.

We have applied the velocity superselection rule proposed by Georgi, Isgur and Wise to some transition matrix element calculations in an extended way. We have found that by the approach , is about which is consistent with the potential model calculations.

A method for universally treating the quark pair with a vacuum quantum number is proposed and it is applied to calculating some charm meson decays as examples. The smallness for W-exchange and annihilation mechanisms has new explanation and the result obtained by means of the proposed method on the decay fits the experimental data well.

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.

A calculation on the rates and the branching ratios of two-body decay of proton and neutron is presented in detail in this paper. A relativistic formalism based on the B.S. wave functions is employed to consider the bound state effects of the quarks inside the nucleon automatically and completely. In order to solve the well-known Van Royen-Weisskopf's paradox occurring in nonrelativistic quark models, a B.S. wave function of mesons with a spin structure different from the Bargmann-Wigner's is accepted and as a result changes in the. branching ratios and the rates are made, e.g. the mode becomes the largest among the two-body modes for the proton decay and the rate for the neutron decay decreases, with the effective interaction induced from the minimum SU(5) model.

An approximate effective Lagrangian of composite operators in superfield formalism for the N=1 pure supersymmetric Yang-Mills model is obtained with the help of renormalization group equations for the generating functional. While the supersymmetry is always kept unbroken by this effective Lagrangian we find that the chiral symmetry may and may not be unbroken.

Some of the important W± and Z decay amplitudes, relating to the chiral anomalies of the quark sector in the Standard Model, are given by means of the interactions determined by the effective Lagrangian (action) of the nonlinear σ model for the pseudogoldstone bosons. The corresponding decay rates are calculated. It is shown that the decay rates are quite large, especially, the rate of the decay W →πγ and probably that of W → Dsγ are predicted being unexpectedly great (ΓW→πγ = 0.35 GeV). This indicates that the chiral anomalies and our approach should receive tests from SPPS and Tevantron experiments.

The compactification of the D = 10 E8 × E8' field theory limit of superstring to the D = 4 SU3×SU2×U1 standard model is investigated by means of the scheme developed by Manton, Forgacs and Chapline.

The exotic fermions occurred in some composite models (such as the family gauged composite model) and their oniums are examined systematically in this paper. It is emphasized that coloured oniums as well as colourless ones may be formed, if their constituents are coloured in high-dimensional representations. According to a rough estimate, the exotic fermions and their oniums should have masses of the order of 0.1 to 1 Tev, hence they may play some roles in the events at energies of SPPS and/or the next generation colliders, if they do exist.

The effective Hamiltonian for nonleptonic decays of strange, charm and beauty, involving the QCD corrections at short distances but with possible t-quark mass mt > mW and a correction of the initial value for the renormalization group equations, is computed in the framework of the operator product expansion (OPE). The numerical results show that our calculation gives corrections in right direction for approaching to the ΔI = 1/2 rule and if using the latest experimental measurements on e and e'/e for system as input, the KM parameter would be constrained in a reasonable region (2.5 ~ 22.5) × 10-3.