Search

We calculate all the branching ratios and direct CP violations of $B \to PV$ decays in a most general two-Higgs-doublet model with spontaneous CP violation. As the model has rich CP-violating sources, it is shown that the new physics effects to direct CP violations and branching ratios in some channels can be significant when adopting the generalized factorization approach to evaluate the hadronic matrix elements, which provides good signals for probing new physics beyond the SM in the future B experiments., Comment: 21 pages

In the heavy quark effective field theory of QCD, we analyze the order 1/m_Q contributions to heavy to light vector decays. Light cone sum rule method is applied with including the effects of 1/m_Q order corrections. We then extract |V_{ub}| from B -> rho l nu decay up to order of 1/m_Q corrections., Comment: 10 pages, revtex, 8 figures

In the heavy quark effective field theory of QCD, we analyze the order 1/m_Q contributions to heavy to light vector decays. Light cone sum rule method is applied with including the effects of 1/m_Q order corrections. We then extract |V_{ub}| from B -> rho l nu decay up to order of 1/m_Q corrections., 10 pages, revtex, 8 figures

In a mini workshop on B Physics which were held at Dalian, China, a number of lectures was given. Around 40 participants joined the workshop. In this workshop, people discussed the heavy quark effective field theory, light cone QCD sum rules and light cone wave functions. Much discussion was devoted to the currently popular QCD factorization and perturbative QCD approaches in the hadronic B decays. The physics of CP violation and physics beyond standard model were also discussed., 20 pages, revtex, including 5 figure

Contributions to B\to ��l ��decay from 1/m_Q order corrections are analyzed in the heavy quark effective field theory (HQEFT) of QCD. Transition wave functions of 1/m_Q order are calculated through light cone sum rule (LCSR) within the HQEFT framework. The results are compared with those from other approaches., 12 pages, revtex, 5 figures

A systematic investigation on muon anomalous magnetic moment and related lepton flavor-violating process such as $\m\to e\g$, $\t\to e\g$ and $\t\to \m\g$ is made at two loop level in the models with flavor-changing scalar interactions. The two loop diagrams with double scalar exchanges are studied and their contributions are found to be compatible with the ones from Barr-Zee diagram. By comparing with the latest data, the allowed ranges for the relevant Yukawa couplings $Y_{ij}$ in lepton sector are obtained. The results show a hierarchical structure of $Y_{\m e, \t e} \ll Y_{\m \t} \simeq Y_{\m\m}$ in the physical basis if $\Delta a_{\mu}$ is found to be $>50\times 10^{-11}$. It deviates from the widely used ansatz in which the off diagonal elements are proportional to the square root of the products of related fermion masses. An alternative Yukawa coupling matrix in the lepton sector is suggested to understand the current data. With such a reasonable Yukawa coupling ansatz, the decay rate of $\t\to \m\g$ is found to be near the current experiment upper bound., Comment: 15 pages, Revtex, 9 figures, published version in EPJC

B --> rho l nu decay is analyzed in the effective theory of heavy quark with infinite mass limit. The matrix element relevant to the heavy to light vector meson semileptonic decays is parametrized by a set of four heavy flavor-spin independent universal wave functions at the leading order of effective theory. The form factors are calculated at the leading 1/m_Q order using the light cone sum rule method in the framework of effective theory. |V_{ub}| is then extracted via B --> rho l nu decay mode., Comment: 10 pages, ReVtex, 2 figures, corrected signs in some formulae

B --> rho l nu decay is analyzed in the effective theory of heavy quark with infinite mass limit. The matrix element relevant to the heavy to light vector meson semileptonic decays is parametrized by a set of four heavy flavor-spin independent universal wave functions at the leading order of effective theory. The form factors are calculated at the leading 1/m_Q order using the light cone sum rule method in the framework of effective theory. |V_{ub}| is then extracted via B --> rho l nu decay mode., 10 pages, ReVtex, 2 figures, corrected signs in some formulae

CP violation, fermion masses and mixing angles including that of neutrinos are studied in an SUSY SO(10)$\times \Delta (48)\times$ U(1) model. The nonabelian SU(3) discrete family symmetry $\Delta(48)$ associated with a simple scheme of U(1) charge assignment on various fields concerned in superpotential leads to unique Yukawa coupling matrices with zero textures. Thirteen parameters involving masses and mixing angles in the quark and charged lepton sector are successfully predicted by only four parameters. The masses and mixing angles for the neutrino sector could also be predicted by constructing an appropriate heavy Majorana neutrino mass matrix without involving new parameters. It is found that the atmospheric neutrino deficit, the mass limit put by hot dark matter and the LSND $\bar{\nu}_{\mu} \to \bar{\nu}_{e}$ events may simultaneously be explained, but solar neutrino puzzle can be solved only by introducing a sterile neutrino. An additional parameter is added to obtain the mass and mixing of the sterile neutrino. The hadronic parameters $B_{K}$ and $f_{B}\sqrt{B}$ are extracted from the observed $K^{0}$-$\bar{K}^{0}$ and $B^{0}$-$\bar{B}^{0}$ mixings respectively. The direct CP violation ($\epsilon'/\epsilon$) in kaon decays and the three angles $\alpha$, $\beta$ and $\gamma$ of the unitarity triangle in the CKM matrix are also presented. More precise measurements of $\alpha_{s}(M_{Z})$, $|V_{cb}|$, $|V_{ub}/V_{cb}|$, $m_{t}$, as well as various CP violation and neutrino oscillation experiments will provide an important test for the present model and guide us to a more fundamental theory., Comment: RevTex, a footnote and references added, contributed paper published in the Proceedings: ``Symposium on Frontiers of Physics at Millennium'', 8-11 Oct. 1999, Beijing, (World Scientific Publishing Company), Editors: Yue-Liang Wu and Jong-Ping Hsu

New physics effects on the $B^0-\bar{B}^0$ mixing and B-decay amplitudes are discussed. By a combined analysis, the model of new physics can be partially distinguished.It is emphasized that the extraction of unitarity angles $\beta$ and $\gamma$ through rare decay $K\to \pi\nu\tilde{\nu}$ and charged B decay $B^{\pm}\to DK^{\pm}$ respectively is not likely to be affected by new physics. Such an observation could be used to distinguish the new physics effects from different mode ls. For instance, the top quark two-Higgs doublet model can be easily separated from those models without new phase in B-decay amplitudes, and can be further distinguished from the most general two Higgs doublet model by its absence of new phase in the $B^0-\bar{B}^0$ mixing., Comment: minor changes and references added

New physics effects on the $B^0-\bar{B}^0$ mixing and B-decay amplitudes are discussed. By a combined analysis, the model of new physics can be partially distinguished.It is emphasized that the extraction of unitarity angles $��$ and $��$ through rare decay $K\to ����\tilde��$ and charged B decay $B^{\pm}\to DK^{\pm}$ respectively is not likely to be affected by new physics. Such an observation could be used to distinguish the new physics effects from different mode ls. For instance, the top quark two-Higgs doublet model can be easily separated from those models without new phase in B-decay amplitudes, and can be further distinguished from the most general two Higgs doublet model by its absence of new phase in the $B^0-\bar{B}^0$ mixing., minor changes and references added

The heavy quark effective field theory (HQEFT) containing both effective `quark fields' and `antiquark fields' is investigated in detail. By integrating out (but not neglecting) the effective antiquark fields, we present a new formulation of effective theory which differs from the usual heavy quark effective theory (HQET) and exhibits valuable features because of the inclusion of the contributions from the antiquark fields. Matrix elements of vector and axial vector heavy quark currents between pseudoscalar and vector mesons containing a heavy quark (b or c) are then evaluated systematically up to the order of $1/m^2_Q$ and parameterized by a set of universal form factors. With a consistent normalization condition between the effective heavy hadron states, the form factors at zero recoil are related to the ground state meson masses, which enables us to estimate the values of form factors at zero recoil. In particular, the Luke's theorem comes out automatically in the new formulation of HQEFT without the need of imposing the equation of motion $iv\cdot D Q^{+}_{v} =0$. Consequently, the differential decay rates of both $B\to D^{\ast}l\nu$ and $B\to D l\nu$ do not receive $1/m_{Q}$ order corrections at zero recoil, which is not the case in the usual HQET. Thus we quote that the Cabibbo-Kobayashi-Maskawa matrix element $| V_{cb}|$ can nicely be extracted from either of these two exclusive semileptonic decays at the order of $1/m^2_Q$. Our estimates for $|V_{cb}|$ are presented., Comment: 28 pages, Revtex, 5 figures, 3 tables, minor changes with "dressed heavy quark" being addressed, to be published in Int. J. Mod. Phys. A

A phenomenological analysis of the general two Higgs doublet model is presented. Possible constraints of the Yukawa couplings are obtained from the $K^0-\bar{K}^0, B^0-\bar{B}^0$ and $D^0-\bar{D}^0$ mixings. A much larger $D^0-\bar{D}^0$ mixing than the standard model prediction is possible. It is shown that the emerging of various new sources of CP violation in the model could strongly affect the determination of the unitarity triangle. It can be helpful to look for a signal of new physics by comparing the extracted angle $\beta$ from two different ways, such as from the process $B\to J/\psi K_{S}$ and from fitting the quantities $|V_{ub}|, \Delta m_{B}$ and $\epsilon$., Comment: 16 pages, Revtex, 7 figures, references added

The influence of strong and electroweak penguin amplitudes in $B/ \bar B \rightarrow \pi^+\pi^-$ is investigated in connection with the determination of the unitarity triangle angle $\alpha$ of the CKM matrix. A relation between the observable asymmetry, the angle $\alpha$, and the penguin amplitude is established. A model calculation of the penguin amplitude shows that the CP asymmetry in $B^{0}\rightarrow \pi^{+}\pi^{-}$ decays is only mildly influenced by the penguin amplitudes. Experimental limits on pure penguin and penguin dominated processes are consistent with the model. This information also suggests in a rather model independent way that penguin amplitudes will not be a serious complicating factor in the determination of $\alpha$ from the $\pi^{+}\pi^{-}$ time dependent asymmetry., Comment: 15 pages, Latex, three figures available upon request

Fermion masses and mixing angles are studied in an SUSY $SO(10)\times \Delta (48)\times U(1)$ model with small $\tan\beta$. Thirteen parameters involving masses and mixing angles in the quark and charged lepton sector are successfully predicted by a single Yukawa coupling and three ratios of VEVs caused by necessary symmetry breaking. Ten relations among the low energy parameters have been found with four of them free from renormalization modifications. They could be tested directly by low energy experiments., Comment: Journal version, Rapid Communication in Phys. Rev. D 53, No.7 (1996)

Fermion masses and mixing angles including that of neutrinos are studied in a model with symmetry group SUSY $SO(10)\times \Delta (48) \times U(1)$. Universality of Yukawa coupling of superfields is assumed. The resulting texture of mass matrices in the low energy region depends only on a single coupling constant and VEVs caused by necessary symmetry breaking. 13 parameters involving masses and mixing angles in the quark and charged lepton sector are successfully described by only five parameters with two of them determined by the scales of U(1), SO(10) and SU(5) symmetry breaking compatible with the requirement of grand unification and proton decay. The neutrino masses and mixing angles in the leptonic sector are also determined with the addition of a Majorana coupling term. It is found that LSND $\bar{\nu}_{\mu}\rightarrow \bar{\nu}_{e}$ events, atmospheric neutrino deficit and the mass limit put by hot dark matter can be naturally explained. Solar neutrino puzzle can be solved only by introducing sterile neutrino with one additional parameter. More precise measurements of $\alpha_{s}(M_{Z})$, $V_{cb}$, $V_{ub}/V_{cb}$, $m_{b}$, $m_{t}$, as well as various CP violation and neutrino oscillation experiments will provide crucial tests of the present model., Comment: 19 pages, RevTex, no Figures, to be published in Scientia Sinica

The influence of strong and electroweak penguin amplitudes in $B/ \bar B \rightarrow ��^+��^-$ is investigated in connection with the determination of the unitarity triangle angle $��$ of the CKM matrix. A relation between the observable asymmetry, the angle $��$, and the penguin amplitude is established. A model calculation of the penguin amplitude shows that the CP asymmetry in $B^{0}\rightarrow ��^{+}��^{-}$ decays is only mildly influenced by the penguin amplitudes. Experimental limits on pure penguin and penguin dominated processes are consistent with the model. This information also suggests in a rather model independent way that penguin amplitudes will not be a serious complicating factor in the determination of $��$ from the $��^{+}��^{-}$ time dependent asymmetry., 15 pages, Latex, three figures available upon request

Motivated by recent experiments at LEP ($Z \to l^+l^-\gamma\gamma$, with $M_{\gamma\gamma} \simeq 59 GeV$), we examine the possibility that such events are explained by a Bjorken process with a resonant Higgs ($M_{h^o} \simeq 59 GeV$) decaying to $\gamma\gamma$. Our model is an N-doublet-Higgs model without CP-violation. Under the simplifying assumption that $(N-k)$ doublets ($k \geq 1$) decouple from the fermion sector, we could explain the observed events if: i) $(N-1) \geq 2$ and ii) the masses of the corresponding $(N-1)$ neutral scalars are either completely or almost degenerate, i.e. the decay $Z \to l^+l^- \gamma\gamma$ proceeds now via several overlapping resonances., Comment: 10 pages

Motivated by recent experiments at LEP ($Z \to l^+l^-����$, with $M_{����} \simeq 59 GeV$), we examine the possibility that such events are explained by a Bjorken process with a resonant Higgs ($M_{h^o} \simeq 59 GeV$) decaying to $����$. Our model is an N-doublet-Higgs model without CP-violation. Under the simplifying assumption that $(N-k)$ doublets ($k \geq 1$) decouple from the fermion sector, we could explain the observed events if: i) $(N-1) \geq 2$ and ii) the masses of the corresponding $(N-1)$ neutral scalars are either completely or almost degenerate, i.e. the decay $Z \to l^+l^- ����$ proceeds now via several overlapping resonances., 10 pages