arXiv subjects

Yue-Liang Wu

Publications and source records attributed to Yue-Liang Wu.

At least 163 records · Page 9Linked to original sources

arXiv2008

One-Loop Renormalization of Non-Abelian Gauge Theory and βFunction Based on Loop Regularization Method

All one-loop renormalization constants for Non-Abelian gauge theory are computed in details by using the symmetry-preserving Loop Regularization method proposed in\cite{LR1,LR2}. The resulting renormalization constants are manifestly shown to satisfy Ward-Takahaski-Slavnov-Taylor identities, and lead to the well-known one loop $β$ function for Non-Abelian gauge theory of QCD\cite{GWP}. The loop regularization method is realized in the dimension of original field theories, it maintains not only symmetries but also divergent behaviors of original field theories with the introduction of two energy scales. Such two scales play the roles of characterizing and sliding energy scales as well as ultraviolet and infrared cutoff energy scales. An explicit Check of those identities provides a clear demonstration how the symmetry-preserving Loop Regularization method can consistently be applied to non-Abelian gauge theories.

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arXiv2008

Exclusive $B \to VV $ Decays and CP Violation in the General two-Higgs-doublet Model

Using the general factorization approach, we present a detailed investigation for the branching ratios, CP asymmetries and longitudinal polarization fractions in all charmless hadronic $B \to VV$ decays (except for the pure annihilation processes) within the most general two-Higgs-doublet model with spontaneous CP violation. It is seen that such a new physics model only has very small contributions to the branching ratios and longitudinal polarization fractions. However, as the model has rich CP-violating sources, it can lead to significant effects on the CP asymmetries, especially on those of penguin-dominated decay modes, which provides good signals for probing new physics beyond the SM in the future B-physics experiments.

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arXiv2007

Constraining Charming Penguins in Charmless B Decays

We discuss the correlations of charming penguin contributions to $B\toππ$, $πK$ and KK using approximate flavor SU(3) symmetry. Strong constraints are found from the direct CP asymmetries especially in $πK$ modes. We make a global fit to the latest data and find that only a small charming penguin is allowed, and the size of color-suppressed tree amplitude (C) relative to tree amplitudes (T) remains large $C/T\simeq0.6$, which disfavors the possibility of a large charming penguin as an explanation for the $ππ$ puzzle. We show that a small charming penguin can still have sizable effect in the time-dependence CP asymmetries in KK mode.

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arXiv2007

A Two Higgs Bi-doublet Left-Right Model With Spontaneous CP Violation

We discuss a left-right symmetric model with two Higgs bi-doublet and spontaneous P and CP violation. The flavor changing neutral currents is suppressed by assuming approximate global U(1) family symmetry. We calculate the constraints from neural K meson mass difference Δm_K and demonstrate that a right-handed gauge boson W_2 contribution in box-diagrams with mass around 600 GeV is allowed due to a negative interference with a light charged Higgs boson around 150 \sim 300 GeV. The W_2 contribution to ε_K is suppressed from appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa(CKM) matrix. The model is found fully consistent with B^0 mass difference and the mixing-induced CP asymmetry measurements.

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arXiv2007

QCD Approach to B->D πDecays and CP Violation

The branching ratios and CP violations of the $B\to Dπ$ decays, including both the color-allowed and the color-suppressed modes, are investigated in detail within QCD framework by considering all diagrams which lead to three effective currents of two quarks. An intrinsic mass scale as a dynamical gluon mass is introduced to treat the infrared divergence caused by the soft collinear approximation in the endpoint regions, and the Cutkosky rule is adopted to deal with a physical-region singularity of the on mass-shell quark propagators. When the dynamical gluon mass $μ_g$ is regarded as a universal scale, it is extracted to be around $μ_g = 440$ MeV from one of the well-measured $B\to Dπ$ decay modes. The resulting predictions for all branching ratios are in agreement with the current experimental measurements. As these decays have no penguin contributions, there are no direct $CP$ asymmetries. Due to interference between the Cabibbo-suppressed and the Cabibbo-favored amplitudes, mixing-induced CP violations are predicted in the $B\to D^{\pm}π^{\mp}$ decays to be consistent with the experimental data at 1-$σ$ level. More precise measurements will be helpful to extract weak angle $2β+γ$.

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arXiv2007

A Three-Flavor AdS/QCD Model with a Back-Reacted Geometry

A fully back-reaction geometry model of AdS/QCD including the strange quark is described. We find that with the inclusion of the strange quark the impact on the metric is very small and the final predictions are changed only negligibly.

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arXiv2007

On the Radiatively Induced Lorentz and CPT Violating Chern-Simons Term

The radiatively induced Lorentz and CPT violating Chern-Simons terms in QED is calculated based on the recently developed loop regularization method [Y.L. Wu, Int.J.Mod.Phys.A18 (2003) 5363, hep-th/0209021; Y.L. Wu, Mod.Phys.Lett.A19 (2004) 2191, hep-th/0311082] for quantum field theories. It enables us to make general comments on the various results in literature and obtain a consistent result when simultaneously combining the evaluation for the chiral anomaly which has a unique form once the vector current is kept conserved.

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arXiv2007

Maximally Symmetric Minimal Unification Model SO(32) with Three Families in Ten Dimensional Space-time

Based on a maximally symmetric minimal unification hypothesis and a quantum charge-dimension correspondence principle, it is demonstrated that each family of quarks and leptons belongs to the Majorana-Weyl spinor representation of 14-dimensions that relate to quantum spin-isospin-color charges. Families of quarks and leptons attribute to a spinor structure of extra 6-dimensions that relate to quantum family charges. Of particular, it is shown that 10-dimensions relating to quantum spin-family charges form a motional 10-dimensional quantum space-time with a generalized Lorentz symmetry SO(1,9), and 10-dimensions relating to quantum isospin-color charges become a motionless 10-dimensional quantum intrinsic space. Its corresponding 32-component fermions in the spinor representation possess a maximal gauge symmetry SO(32). As a consequence, a maximally symmetric minimal unification model SO(32) containing three families in ten dimensional quantum space-time is naturally obtained by choosing a suitable Majorana-Weyl spinor structure into which quarks and leptons are directly embedded. Both resulting symmetry and dimensions coincide with the ones of type I string and heterotic string SO(32) in string theory.

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arXiv2007

Stability of Proton and Maximally Symmetric Minimal Unification Model for Basic Forces and Building Blocks of Matter

With the hypothesis that all independent degrees of freedom of basic building blocks should be treated equally on the same footing and correlated by a possible maximal symmetry, we arrive at an 4-dimensional space-time unification model. In this model the basic building blocks are Majorana fermions in the spinor representation of 14-dimensional quantum space-time with a gauge symmetry $G = SO(1,3)\times SU(32)\times U(1)_A \times SU(3)_F$. The model leads to new physics including mirror particles of the standard model. It enables us to issue some fundamental questions that include: why our living space-time is 4-dimensional, why parity is not conserved in our world, how is the stability of proton, what is the origin of CP violation and what can be the dark matter.

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arXiv2006

AdS/QCD Phenomenological Models from a Back-Reacted Geometry

We construct a fully back-reacted holographic dual of a four-dimensional field theory which exhibits chiral symmetry breaking. Two possible models are considered by studying the effects of a five-dimensional field, dual to the $q\bar{q}$ operator. One model has smooth geometry at all radii and the other dynamically generates a cutoff at finite radius. Both of these models satisfy Einstein's field equations. The second model has only three free parameters, as in QCD, and we show that this gives phenomenologically consistent results. We also discuss the possibility that in order to obtain linear confinement from a back-reacted model it may be necessary to consider the condensate of a dimension two operator.

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arXiv2006

Z_3 Symmetry and Neutrino Mixing in Type II Seesaw

Neutrino mixing matrix satisfying the current experimental data can be well described by the HPS tri-bimaximal mixing matrix. We propose that its origin can be understood within the seesaw framework by a hidden condition on the mass matrix of heavy right-handed neutrinos under the transformation of the Abelian finite group Z_3 on the flavor basis. Ignoring CP phases, we show that it can lead to the generic form of the effective light neutrino mass matrix from which the HPS mixing matrix appears naturally, as well as an expeimentally allowed non-zero \sinθ_{13}. We show that the model based on our proposal is in good agreement with the current experimental data.

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arXiv2006

Large Strong Phases and CP Violation in the Annihilation Processes $\bar{B}^0\to K^+K^-$, $K^{\pm}K^\mp$, $K^{+}K^{*-}$

The strong phases and CP violation in the rare $\bar{B}^0\to K^+K^-$, $K^{*\pm}K^\mp$, $K^{*+}K^{*-}$ decays are investigated. As these decays proceed only via annihilation type diagrams in the standard model (SM), a dynamical gluon mass is introduced to avoid the infrared divergence in the soft endpoint regions. The Cutkosky rule is adopted to deal with a physical-region singularity of the on mass-shell quark propagators, which leads to a big imaginary part and hence a large strong phase. As a consequence, large CP asymmetries are predicted in those decay modes due to a big interference between the annihilation amplitudes from penguin and tree operators, which may be tested in future more precise experiments.

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arXiv2006

Large Component QCD and Theoretical Framework of Heavy Quark Effective Field Theory

Based on a large component QCD derived directly from full QCD by integrating over the small components of quark fields with $|{\bf p}| < E + m_Q$, an alternative quantization procedure is adopted to establish a basic theoretical framework of heavy quark effective field theory (HQEFT) in the sense of effective quantum field theory. The procedure concerns quantum generators of Poincare group, Hilbert and Fock space, anticommutations and velocity super-selection rule, propagator and Feynman rules, finite mass corrections, trivialization of gluon couplings and renormalization of Wilson loop. The Lorentz invariance and discrete symmetries in HQEFT are explicitly illustrated. Some new symmetries in the infinite mass limit are discussed. Weak transition matrix elements and masses of hadrons in HQEFT are well defined to display a manifest spin-flavor symmetry and $1/m_Q$ corrections. A simple trace formulation approach is explicitly demonstrated by using LSZ reduction formula in HQEFT, and shown to be very useful for parameterizing the transition form factors via $1/m_Q$ expansion. As the heavy quark and antiquark fields in HQEFT are treated on the same footing in a fully symmetric way, the quark-antiquark coupling terms naturally appear and play important roles for simplifying the structure of transition matrix elements, and for understanding the concept of `dressed heavy quark' - hadron duality. In the case that the `longitudinal' and `transverse' residual momenta of heavy quark are at the same order of power counting, HQEFT provides a consistent approach for systematically analyzing heavy quark expansion in terms of $1/m_Q$. Some interesting features in applications of HQEFT to heavy hadron systems are briefly outlined.

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arXiv2006

Implications of new data in charmless B decays

Based on the latest experimental data of $B \to ππ$ and $πK$ modes, a model-independent analytical analysis is presented. The CP-averaged branching ratio difference $ΔR = R_c - R_n$ in $B\to πK$ decays with $R_c = 2Br(π^0K^-)/Br(π^-\bar{K}^0)$ and $R_n =Br(π^+K^-)/2Br(π^0\bar{K}^0)$ is reduced though it remains larger than the prediction from the standard model(SM) as both measured $R_n$ and $R_c$ are enhanced, which indicates that a room for new physics becomes smaller. The present data of $ππ$ decay reduce the ratio $|C/T|$ from the previous value of $|C/T|\simeq 0.8 $ to $|C/T| \simeq 0.65$, which is still larger than the theoretical estimations based on QCD factorization and pQCD. Within SM and flavor SU(3) symmetry, the current $πK$ data also diminish the ratio $|C'/T'|$ from the previous value $|C'/T'| \simeq 2$ to $|C'/T'| \simeq 1.16$ with a large strong phase $δ_{C'} \simeq -2.65$, while its value remains much larger than the one extracted from the $ππ$ modes. The direct CP violation $A_{CP}(π^0\bar{K}^0)$ is predicted to be $A_{CP}(π^0\bar{K}^0) = -0.15\pm0.03$, which is consistent with the present data. Two kinds of new effects in both strong and weak phases of the electroweak penguin diagram are considered. It is found that both cases can reduce the ratio to $|C'/T'| = 0.40\sim 0.80$ and lead to roughly the same predictions for CP violation in $π^0 K^0$.

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arXiv2006

Embedding Flipped SU(5) into SO(10)

We embed the flipped SU(5) models into the SO(10) models. After the SO(10) gauge symmetry is broken down to the flipped SU(5) \times U(1)_X gauge symmetry, we can split the five/one-plets and ten-plets in the spinor \mathbf{16} and \mathbf{\bar{16}} Higgs fields via the stable sliding singlet mechanism. As in the flipped SU(5) models, these ten-plet Higgs fields can break the flipped SU(5) gauge symmetry down to the Standard Model gauge symmetry. The doublet-triplet splitting problem can be solved naturally by the missing partner mechanism, and the Higgsino-exchange mediated proton decay can be suppressed elegantly. Moreover, we show that there exists one pair of the light Higgs doublets for the electroweak gauge symmetry breaking. Because there exist two pairs of additional vector-like particles with similar intermediate-scale masses, the SU(5) and U(1)_X gauge couplings can be unified at the GUT scale which is reasonably (about one or two orders) higher than the SU(2)_L \times SU(3)_C unification scale. Furthermore, we briefly discuss the simplest SO(10) model with flipped SU(5) embedding, and point out that it can not work without fine-tuning.

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arXiv2006

Signal of New Physics and Test of Isospin-SU(3) Relations and CP Violation in Charmless B Decays

A model-independent analytical analysis for charmless B decays is presented. It is demonstrated that the CP-averaging branching ratio difference $ΔR = R_c - R_n$ in $B\to πK$ decays with $R_c = 2Br(π^0K^-)/Br(π^-\bar{K}^0)$ and $R_n =Br(π^+K^-)/2Br(π^0\bar{K}^0)$ defines a sensitive quantity for probing new physics as $ΔR$ is dominated by the second order of electroweak penguin contributions. A large discrepancy between experimental data and standard model (SM) prediction $ΔR^{exp}/ΔR^{SM} > 9.0\pm 5.0$ strongly indicates a signal of new physics in the electroweak penguin sector. Within the SM, the current $πK$ data favor a very large color-suppressed tree amplitude $|C'/T'|\sim 2$, large CP violations ($A_{CP}(π^0\bar{K}^0)\sim 0.69$ and $A_{CP}(π^0\bar{K}^-)\sim 0.56$), which is connected to $ΔR$ and be solved simultaneously with extra electroweak penguin contributions. More accurate measurements on the ratio difference $ΔR$ and CP violation in $B\to ππ, πK$ decays may provide a window for probing new physics and testing the isospin and SU(3) symmetries.

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arXiv2006

$B_{(s)},D_{(s)} \to π, K, η, ρ, K^*, ω, ϕ$ Transition Form Factors and Decay Rates with Extraction of the CKM parameters $|V_{ub}|$, $|V_{cs}|$, $|V_{cd}|$

A systematic calculation for the transition form factors of heavy to light mesons ($B,B_s,D,D_s \to π, K, η, ρ, K^*, ω, ϕ$) is carried out by using light-cone sum rules in the framework of heavy quark effective field theory. The heavy quark symmetry at the leading order of $1/m_Q$ expansion enables us to reduce the independent wave functions and establish interesting relations among form factors. Some relations hold for the whole region of momentum transfer. The meson distribution amplitudes up to twist-4 including the contributions from higher conformal spin partial waves and light meson mass corrections are considered. The CKM matrix elements $|V_{ub}|$, $|V_{cs}|$ and $|V_{cd}|$ are extracted from some relatively well-measured decay channels. A detailed prediction for the branching ratios of heavy to light meson decays is then presented. The resulting predictions for the semileptonic and radiative decay rates of heavy to light mesons ($B,B_s,D,D_s \to π, K, η, ρ, K^*, ω, ϕ$) are found to be compatible with the current experimental data and can be tested by more precise experiments at B-factory, LHCb, BEPCII and CLEOc.

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arXiv2006

Anomaly and Anomaly-Free Treatment of QFTs Based on Symmetry-preserving Loop Regularization

The triangle anomaly in massless and massive QED is investigated by adopting the symmetry-preserving loop regularization method proposed recently in \cite{LR}. The method is realized in the initial dimension of theory without modifying the original lagrangian, it preserves symmetries under non-Abelian gauge and Poincare transformations in spite of the existence of two intrinsic mass scales $M_c$ and $μ_s$ which actually play the roles of UV- and IR-cut off respectively. The axialvector-vector-vector (AVV) triangle diagrams in massless and massive QED are evaluated explicitly by using the loop regularization. It is shown that when the momentum $k$ of external state is soft with $k^2 \ll μ_s^2, m^2 $ ($m$ is the mass of loop fermions) and $ M_c \to \infty$, both massless and massive QED become anomaly free. The triangle anomaly is found to appear as quantum corrections in the case that $ m^2, μ_s^2 \ll k^2 $ and $M_c \to \infty$. Especially, it is justified that in the massless QED with $μ_s =0$ and $M_c\to \infty$, the triangle anomaly naturally exists as quantum effects in the axial-vector current when the ambiguity caused by the trace of gamma matrices with $γ_5$ is eliminated by simply using the definition of $γ_5$. It is explicitly demonstrated how the Ward identity anomaly of currents depends on the treatment for the trace of gamma matrices, which enables us to make a clarification whether the ambiguity of triangle anomaly is caused by the regularization scheme in the perturbation calculations or by the trace of gamma matrices with $γ_5$.

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