arXiv subjects

Yue-Liang Wu

Publications and source records attributed to Yue-Liang Wu.

At least 145 records · Page 8Linked to original sources

arXiv2010

Searching for Dark Matter Signals in the Left-Right Symmetric Gauge Model with CP Symmetry

We investigate singlet scalar dark matter (DM) candidate in a left-right symmetric gauge model with two Higgs bidoublets (2HBDM) in which the stabilization of the DM particle is induced by the discrete symmetries P and CP. According to the observed DM abundance, we predict the DM direct and indirect detection cross sections for the DM mass range from 10 GeV to 500 GeV. We show that the DM indirect detection cross section is not sensitive to the light Higgs mixing and Yukawa couplings except the resonance regions. The predicted spin-independent DM-nucleon elastic scattering cross section is found to be significantly dependent on the above two factors. Our results show that the future DM direct search experiments can cover the most parts of the allowed parameter space. The PAMELA antiproton data can only exclude two very narrow regions in the 2HBDM. It is very difficult to detect the DM direct or indirect signals in the resonance regions due to the Breit-Wigner resonance effect.

hep-ph↗

arXiv2010

Charmless $B\to PP, PV, VV$ Decays Based on the six-quark Effective Hamiltonian with Strong Phase Effects

Based on an approximate six-quark operator effective Hamiltonian from perturbative QCD, we present a systematical study of charmless $B \to PP, PV, VV$ decays ($P$ and $V$ denoting pseudoscalar and vector mesons, respectively). The calculation of the relevant hard-scattering kernels is completed, the resulting transition form factors are consistent with the results of QCD sum rule calculation. Important classes of power corrections include "chirally-enhanced" terms, vertex corrections and weak annihilation contributions with non-trivial strong phase. With these considerations, predictions are presented for the branching ratios and CP asymmetries of B-meson decays into PP, PV and VV final states, and also for the corresponding polarization observables in VV final states. Several decay modes and observables, which are of particular interest phenomenologically, are discussed in detail, including the effect of annihilation amplitude with strong phase, the $ππ$, $πK$ and $πρ$ systems, the longitudinal polarization fraction $f_L$ in $ρK^*$ and $ϕK^*$ systems and so on. It is observed that predictions in our framework generally agree with the current experimental data.

hep-ph↗

arXiv2010

Time-Varying Dark Energy Constraints From the Latest SN Ia, BAO and SGL

Based on the latest SNe Ia data provided by Hicken et al. (2009) with using MLCS17 light curve fitter, together with the Baryon Acoustic Oscillation(BAO) and strong gravitational lenses(SGL), we investigate the constraints on the dark energy equation-of-state parameter $w$ in the flat universe, especially for the time-varying case $w(z)=w_0+w_zz/(1+z)$. The constraints from SNe data alone are found to be: (a) $(Ω_M, w)=(0.358, -1.09)$ as the best-fit results; (b) $(w_0, w_z)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34})$ for the two parameters in the time-varying case after marginalizing the parameter $Ω_M$; (c) the likelihood of parameter $w_z$ has a high non-Gaussian distribution; (d) an extra restriction on $Ω_M$ is necessary to improve the constraint of the SNe Ia data on the parameters ($w_0$, $w_z$). A joint analysis of SNe Ia data and BAO is made to break the degeneracy between $w$ and $Ω_M$, and leads to the interesting maximum likelihoods $w_0 = -0.94$ and $w_z = 0$. When marginalizing the parameter $Ω_M$, the fitting results are found to be $(w_0, w_z)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96})$. After adding the splitting angle statistic of SGL data, a consistent constraint is obtained $(Ω_M, w)=(0.298, -0.907)$ and the constraints on time-varying dark energy are further improved to be $(w_0, w_z) = (-0.92^{+0.14}_{-0.10}, 0.35^{+0.47}_{-0.54})$, which indicates that the phantom type models are disfavored.

astro-ph.CO↗

arXiv2010

Neutral Higgs production on LHC in the two-Higgs-doublet model with spontaneous $CP$ violation

Spontaneous CP violation motivates the introduction of two Higgs doublets in the electroweak theory, such a simple extension of the standard model has five physical Higgs bosons and rich CP-violating sources. Exploration on more than one Higgs boson is a direct evidence for new physics beyond the standard model. The neutral Higgs production at LHC is investigated in such a general two Higgs doublet model with spontaneous CP violation, it is shown that the production cross section and decays of the neutral Higgs boson can significantly be different from the predictions from the standard model.

hep-ph↗

arXiv2010

Heavy Quark Expansion in 1/\hat{m}_Q and |V_{cb}| Extraction

The dressed heavy quark mass \hat{m}_Q=m_Q+\bar{Λ} with \bar{Λ} being the binding energy is introduced to characterize the heavy hadrons containing a single heavy quark. A heavy quark expansion in terms of the inverse of the dressed heavy quark mass 1/\hat{m}_Q is presented with a complete decomposition of the full field and integrating out the small components. The heavy quark-antiquark coupling effects are included in the finite mass corrections. It is shown that the 1/\hat{m}_Q expansion is more favorable in application. The extraction of |V_{cb}| from exclusive B decays is studied by using such a new expansion approach.

hep-ph↗

arXiv2010

Fluctuations and Correlations of Conserved Charges in QCD at Finite Temperature with Effective Models

We study fluctuations of conserved charges including baryon number, electric charge, and strangeness as well as the correlations among these conserved charges in the 2+1 flavor Polyakov--Nambu--Jona-Lasinio model at finite temperature. The calculated results are compared with those obtained from recent lattice calculations performed with an improved staggered fermion action at two values of the lattice cutoff with almost physical up and down quark masses and a physical value for the strange quark mass. We find that our calculated results are well consistent with those obtained in lattice calculations except for some quantitative differences for fluctuations related with strange quarks. Our calculations indicate that there is a pronounced cusp in the ratio of the quartic to quadratic fluctuations of baryon number, i.e. $χ_{4}^{B}/χ_{2}^{B}$, at the critical temperature during the phase transition, which confirms that $χ_{4}^{B}/χ_{2}^{B}$ is a useful probe of the deconfinement and chiral phase transition.

hep-ph↗

arXiv2010

Prediction for the Mass Spectra of Resonance Mesons in the Soft-Wall AdS/QCD with a Modified 5D Metric

A soft-wall anti-de Sitter/QCD model with a modified five-dimensional metric at the infrared region is constructed to obtain a nontrivial dilaton solution, which incorporates the chiral symmetry breaking and linear confinement. By taking the pion mass and decay constant as two input mass scales, the resulting predictions for the resonance states of pseudoscalar, scalar, vector and axial-vector mesons agree remarkably with the experimentally confirmed resonance states. The effects of the quartic interaction term are investigated by taking an appropriate sign and magnitude for maintaining the stability of the bulk scalar potential. It is shown that such a simply modified soft-wall anti-de Sitter/QCD model can lead to a consistent prediction for the mass spectra of resonance states in the pseudoscalar, scalar, vector and axial-vector mesons; the agreement with the experimental data is found to be better than 10% for the excited meson states. The resulting pion form factor also agrees well with the experimental data.

hep-ph↗

arXiv2010

Exploration of decaying dark matter in a left-right symmetric model

$SU(2)_L$ triplet scalars appear in models motivated for the left-right symmetry, neutrino masses and dark matter (DM), etc.. If the triplets are the main decay products of the DM particle, and carry nonzero lepton numbers, they may decay dominantly into lepton pairs, which can naturally explain the current experimental results reported by PAMELA and Fermi-LAT or ATIC. We discuss this possibility in an extended left-right symmetric model in which the decay of DM particle is induced by tiny soft charge-conjugation ($C$) violating interactions, and calculate the spectra for cosmic-ray positrons, neutrinos and gamma-rays. We show that the DM signals in the flux of high energy neutrinos can be significantly enhanced, as the triplets couple to both charged leptons and neutrinos with the same strength. In this scenario, the predicted neutrino-induced muon flux can be several times larger than the case in which DM particle only directly decays into charged leptons. In addition, the charged components of the triplet may give an extra contribution to the high energy gamma-rays through internal bremsstrahlung process, which depends on the mass hierarchy between the DM particle and the triplet scalars.

hep-ph↗

arXiv2009

Dark Energy and Hubble Constant From the Latest SNe Ia, BAO and SGL

Based on the latest MLCS17 SNe Ia data provided by Hicken et al. (2009), together with the Baryon Acoustic Oscillation (BAO) and strong gravitational lenses (SGL), we investigate the dark energy equation-of-state parameter for both constant $w$ and time-varying $w(z)=w_0+w_az/(1+z)$ in the flat universe, and its correlation with the matter density $Ω_M$ and Hubble constant $h$. The constraints from SNe data alone arrive at: (a) the best-fit results are $(Ω_M, w, h)=(0.358, -1.09, 0.647)$, while both $Ω_M$ and $w$ are very sensitive to the difference $Δh =h-\tilde{h}$ of the Hubble constant deviating to the prior input $\tilde{h}=0.65$; (b) the likelihoods of parameters are found to be: $w = -0.88^{+0.31}_{-0.39}$ and $Ω_M=0.36^{+0.09}_{-0.15}$, which is consistent with the $Λ\rm CDM$ at 95% C.L.; (c) the two parameters in the time-varying case are found to be $(w_0, w_a)=(-0.73^{+0.23}_{-0.97}, 0.84^{+1.66}_{-10.34})$ after marginalizing other parameters; (d) there is a clear degeneracy between constant $w$ and $Ω_M$, which depresses the power of SNe Ia to constrain both of them; (e) the likelihood of parameter $w_a$ has a high non-Gaussian distribution; (f) an extra restriction on $Ω_M$ is necessary to improve the constraint of the SNe Ia data on ($w_0$, $w_a$). A joint analysis of SNe Ia data and BAO is made to break the degeneracy between $w$ and $Ω_M$, and it provides a stringent constrain with the likelihoods: $w = -0.88^{+0.07}_{-0.09}$ and $Ω_M=0.29^{+0.02}_{-0.03}$. For the time-varying $w(z)$, it leads to the interesting maximum likelihoods $w_0 = -0.94$ and $w_a = 0$. When marginalizing the parameters $Ω_M$ and $h$, the fitting results are found to be $(w_0, w_a)=(-0.95^{+0.45}_{-0.18}, 0.41^{+0.79}_{-0.96})$.

astro-ph.CO↗

arXiv2009

Renormalization of Supersymmetric Field Theories in Loop Regularization with String-mode Regulators

By applying the recently developed Loop Regularization(LR) with string-mode regulators to supersymmetric field theories, we explicitly verify the supersymmetric Ward identities in several supersymmetric models at one-loop level. It is interesting to observe that supersymmetry is a so remarkable symmetry that the supersymmetric Ward identities hold as long as a regularization scheme is realized in the exact four dimensional space-time with translational invariance for the momentum integration, and the gauge symmetry can be maintained once the regularization scheme preserves supersymmetry and satisfies the consistency condition for logarithmic divergences. As a manifest demonstration, we carry out a complete one-loop renormalization for the massive Wess-Zumino model by adopting the LR method, it is found that all the quadratic divergences cancel out and the relations among masses and coupling constants hold after renormalization, which agrees with the well-known non-renormalization theorem. It is concluded that the LR method preserves not only gauge symmetry but also supersymmetry. A simple and definite derivation of Majorana Feynman rules is found to be very useful.

hep-ph↗

arXiv2009

Enhancement of Dark Matter Annihilation via Breit-Wigner Resonance

The Breit-Wigner enhancement of the thermally averaged annihilation cross section <σv> is shown to provide a large boost factor when the dark matter annihilation process nears a narrow resonance. We explicitly demonstrate the evolution behavior of the Breit-Wigner enhanced <σv> as the function of universe temperature for both the physical and unphysical pole cases. It is found that both of the cases can lead an enough large boost factor to explain the recent PAMELA, ATIC and PPB-BETS anomalies. We also calculate the coupling of annihilation process, which is useful for an appropriate model building to give the desired dark matter relic density.

hep-ph↗

arXiv2008

Constraining Dark Energy From Splitting Angle Statistic of Strong Gravitational Lenses

Utilizing the CLASS statistical sample, we investigate the constraint of the splitting angle statistic of strong gravitational lenses(SGL) on the equation-of-state parameter $w=p/ρ$ of the dark energy in the flat cold dark matter cosmology. Through the comoving number density of dark halos described by Press-Schechter theory, dark energy affects the efficiency with which dark-matter concentrations produce strong lensing signals. The constraints on both constant $w$ and time-varying $w(z)=w_0+w_az/(1+z)$ from the SGL splitting angle statistic are consistently obtained by adopting a two model combined mechanism of dark halo density profile matched at the mass scale $M_c$. Our main observations are: (a) the resulting model parameter $M_c$ is found to be $M_c \sim 1.4$ for both constant $w$ and time-varying $w(z)$, which is larger than $M_c \sim 1$ obtained in literatures; (b) the fitting results for the constant $w$ are found to be $w =-0.89^{+0.49}_{-0.26}$ and $w =-0.94^{+0.57}_{-0.16}$ for the source redshift distributions of the Gaussian models $g(z_s)$ and $g^c(z_s)$ respectively, which are consistent with the $Λ\rm CDM$ at 95% C.L; (c) the time-varying $w(z)$ is found to be for $σ_8 = 0.74$: $(M_c; w_0, w_a)=(1.36; -0.92, -1.31)$ and $(M_c; w_0, w_a)=(1.38; -0.89, -1.21)$ for $g(z_s)$ and $g^c(z_s)$ respectively.

astro-ph↗

arXiv2008

Gauge-singlet dark matter in a left-right symmetric model with spontaneous CP violation

We propose a dark matter (DM) scenario in an extension of a left-right symmetric model with a gauge-singlet scalar field. The gauge-singlet scalar can automatically become a DM candidate, provided that both P and CP symmetries are only broken spontaneously. Thus no extra discrete symmetries are needed to make the DM candidate stable. After constraining the model parameters from the observed relic DM density we make predictions for direct detection experiments. We show that for some parameter range, the predicted WIMP-nucleon elastic scattering cross section can reach the current experimental upper bound, which can be tested by the experiments in the near future.

hep-ph↗

arXiv2008

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

A left-right symmetric model with two Higgs bi-doublet is shown to be a consistent model for both spontaneous P and CP violation. The flavor changing neutral currents can be suppressed by the mechanism of 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 well below 1 TeV is allowed due to a cancellation caused by a light charged Higgs boson with a mass range $150 \sim 300$ GeV. The $W_2$ contribution to $ε_K$ can be suppressed from appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa matrix. The model is also found to be fully consistent with $B^0$ mass difference $Δm_B$, and the mixing-induced CP violation quantity $\sin2β_{J/ψ}$, which is usually difficult for the model with only one Higgs bi-doublet. The new physics beyond the standard model can be directly searched at the colliders LHC and ILC.

hep-ph↗

arXiv2008

Symmetry Principle Preserving and Infinity Free Regularization and renormalization of quantum field theories and the mass gap

Through defining irreducible loop integrals (ILIs), a set of consistency conditions for the regularized (quadratically and logarithmically) divergent ILIs are obtained to maintain the generalized Ward identities of gauge invariance in non-Abelian gauge theories. Overlapping UV divergences are explicitly shown to be factorizable in the ILIs and be harmless via suitable subtractions. A new regularization and renormalization method is presented in the initial space-time dimension of the theory. The procedure respects unitarity and causality. Of interest, the method leads to an infinity free renormalization and meanwhile maintains the symmetry principles of the original theory except the intrinsic mass scale caused conformal scaling symmetry breaking and the anomaly induced symmetry breaking. Quantum field theories (QFTs) regularized through the new method are well defined and governed by a physically meaningful characteristic energy scale (CES) $M_c$ and a physically interesting sliding energy scale (SES) $μ_s$ which can run from $μ_s \sim M_c$ to a dynamically generated mass gap $μ_s=μ_c$ or to $μ_s =0$ in the absence of mass gap and infrared (IR) problem. It is strongly indicated that the conformal scaling symmetry and its breaking mechanism play an important role for understanding the mass gap and quark confinement.

hep-th↗

arXiv2008

QCD Factorization Based on Six-Quark Operator Effective Hamiltonian from Perturbative QCD and Charmless Bottom Meson Decays $B_{(s)}\to ππ,πK, KK$

The charmless bottom meson decays are systematically investigated based on an approximate six quark operator effective Hamiltonian from perturbative QCD. It is shown that within this framework the naive QCD factorization method provides a simple way to evaluate the hadronic matrix elements of two body mesonic decays. The singularities caused by on mass-shell quark propagator and gluon exchanging interaction are appropriately treated. Such a simple framework allows us to make theoretical predictions for the decay amplitudes with reasonable input parameters. The resulting theoretical predictions for all the branching ratios and CP asymmetries in the charmless $B^0, B^+, B_s\to ππ, πK, KK$ decays are found to be consistent with the current experimental data except for a few decay modes. The observed large branching ratio in $B\to π^0π^0$ decay remains a puzzle though the predicted branching ratio may be significantly improved by considering the large vertex corrections in the effective Wilson coefficients. More precise measurements of charmless bottom meson decays, especially on CP-violations in $B\to K K$ and $B_s\to ππ, πK, KK$ decay modes, will provide a useful test and guide us to a better understanding on perturbative and nonperturbative QCD.

hep-ph↗

arXiv2008

SO(3) Gauge Symmetry and Nearly Tri-bimaximal Neutrino Mixing

In this note I mainly focus on the neutrino physics part in my talk and report the most recent progress made in \cite{YLW0}. It is seen that the Majorana features of neutrinos and SO(3) gauge flavor symmetry can simultaneously explain the smallness of neutrino masses and nearly tri-bimaximal neutrino mixing when combining together with the mechanism of approximate global U(1) family symmetry. The mixing angle $θ_{13}$ and CP-violating phase are in general nonzero and testable experimentally at the allowed sensitivity. The model also predicts the existence of vector-like Majorana neutrinos and charged leptons as well as new Higgs bosons, some of them can be light and explored at the LHC and ILC.

hep-ph↗

arXiv2008

CP Measurement in Quantum Teleportation of Neutral Mesons

Quantum teleportation using neutral pseudoscalar mesons shows novel connections between particle physics and quantum information. The projection basis, which is crucial in the teleportation process, is determined by the conservation laws of particle physics, and is different from the Bell basis, as in the usual case. Here we show that one can verify the teleportation process by CP measurement. This method significantly simplifies the high energy quantum teleportation protocol. Especially, it is rigorous, and is independent of whether CP is violated in weak decays. This method can also be applied to general verification of Einstein-Podolsky-Rosen correlations in particle physics.

hep-ph↗