arXiv subjects

Ying Li

Publications and source records attributed to Ying Li.

At least 631 records · Page 35Linked to original sources

arXiv2007

Charmless non-leptonic B_s decays to PP, PV and VV final states in the pQCD approach

We calculate the CP-averaged branching ratios and CP-violating asymmetries of a number of two-body charmless hadronic decays $\bar{B_s^0} \to PP, PV, VV$ in the perturbative QCD (pQCD) approach to leading order in $α_s$ (here $P$ and $V$ denote light pseudoscalar and vector mesons, respectively). The mixing-induced CP violation parameters are also calculated for these decays. We also predict the polarization fractions of $B_s \to VV$ decays and find that the transverse polarizations are enhanced in some penguin dominated decays such as $\bar{B_s^0} \to K ^{*}\bar{K^{*}}$, $K ^{*}ρ$. Some of the predictions worked out here can already be confronted with the recently available data from the CDF collaboration on the branching ratios for the decays $ \bar{B_s^0} \to K^+π^-$, $ \bar{B_s^0} \to K^+K^-$ and the CP-asymmetry in the decay $ \bar{B_s^0} \to K^+π^-$, and are found to be in agreement within the current errors. A large number of predictions for the branching ratios, CP-asymmetries and vector-meson polarizations in $\bar{B_s^0}$ decays, presented in this paper and compared with the already existing results in other theoretical frameworks, will be put to stringent experimental tests in forthcoming experiments at Fermilab, LHC and Super B-factories.

hep-ph↗

arXiv2007

Atomic Entanglement vs Photonic Visibility for Quantum Criticality of Hybrid System

To characterize the novel quantum phase transition for a hybrid system consisting of an array of coupled cavities and two-level atoms doped in each cavity, we study the atomic entanglement and photonic visibility in comparison with the quantum fluctuation of total excitations. Analytical and numerical simulation results show the happen of quantum critical phenomenon similar to the Mott insulator to superfluid transition. Here, the contour lines respectively representing the atomic entanglement, photonic visibility and excitation variance in the phase diagram are consistent in the vicinity of the non-analytic locus of atomic concurrences.

quant-ph↗

arXiv2006

Study of scalar mesons f_0(980) and f_0(1500) from $B \to f_0(980) K$ and $B \to f_0(1500) K$ Decays

Within perturbative QCD approach based on $k_T$ factorization, we analyze the scalar mesons $f_0(980)$ and $f_0(1500)$ productions in B decays. By identifying $f_0(980)$ as the composition of $\bar ss$ and $\bar nn=(\bar uu+\bar dd)/\sqrt2$, we calculate the exclusive decays $B\to f_0(980) K$. We find that the non-factorization $f_0$-emission diagrams can give larger contribution to the branching ratio, than the previous PQCD calculation. Our new results can explain the current experimental data well. Under the assumption of quarkonium dominance, we study the branching ratio of decays $B\to f_0(1500) K$. The results show that in the two-quark picture of $f_0$ meson the contribution from $\bar s s$ component is at the similar size as that from the $\bar n n$ component. Comparing with the data, our results show the preference of $f_0(1500)$ as a member of the ground state of scalar $\bar qq$ nonet. Similar results can also apply to $f_0(1370)$ and $f_0(1710)$, if these mesons are dominated by the quarkonium content. With more experimental data in future, these studies will help us understand the intrinsic characters of these scalar mesons.

hep-ph↗

arXiv2006

Annihilation Type Radiative Decays of $B$ Meson in Perturbative QCD Approach

With the perturbative QCD approach based on $k_T$ factorization, we study the pure annihilation type radiative decays $B^0 \to ϕγ$ and $B^0\to J/ψγ$. We find that the branching ratio of $B^0 \to ϕγ$ is $(2.7^{+0.3+1.2}_{-0.6-0.6})\times10^{-11}$, which is too small to be measured in the current $B$ factories of BaBar and Belle. The branching ratio of $B^0\to J/ψγ$ is $({4.5^{+0.6+0.7}_{-0.5-0.6}})\times10^{-7}$, which is just at the corner of being observable in the $B$ factories. A larger branching ratio $BR(B_s^0 \to J/ψγ) \simeq 5 \times 10^{-6}$ is also predicted. These decay modes will help us testing the standard model and searching for new physics signals.

hep-ph↗

arXiv2006

Peierls distorted chain as a quantum data bus for quantum state transfer

We systematically study the transfer of quantum state of electron spin as the flying qubit along a half-filled Peierls distorted tight-binding chain described by the Su-Schrieffer-Heeger (SSH) model, which behaves as a quantum data bus. This enables a novel physical mechanism for quantum communication with always-on interaction: the effective hopping of the spin carrier between sites $A$ and $B$ connected to two sites in this SSH chain can be induced by the quasi-excitations of the SSH model. As we prove, it is the Peierls energy gap of the SSH quasi-excitations that plays a crucial role to protect the robustness of the quantum state transfer process. Moreover, our observation also indicates that such a scheme can also be employed to explore the intrinsic property of the quantum system.

cond-mat.mes-hall↗

arXiv2006

Study of W-exchange Mode $D^0 \to ϕ\bar K^0$

We calculate the branching ratio of $D^0 \to ϕ\bar K^0$ decay using the so-called perturbation QCD approach based on $k_T$ factorization. Our result shows this branching ratio is $(8.7 \pm1.4)\times 10^{-3}$, which is consistent with experimental data. We hope the CLEO-C and BES-III can measure it more accurately, which will help us to understand QCD dynamics and $D$ meson weak decays.

hep-ph↗

arXiv2006

Alignment of Carbon Nanotube Additives for Improved Performance of Magnesium Diboride Superconductors

The rapid progress on MgB2 superconductor since its discovery[1] has made this material a strong competitor to low and high temperature superconductors (HTS) for applications with a great potential to catch the niche market such as in magnetic resonant imaging (MRI). Thanks to the lack of weak links and the two-gap superconductivity of MgB2 [2,3] a number of additives have been successfully used to enhance the critical current density, Jc and the upper critical field, Hc2.[4-12] Carbon nanotubes (CNTs) have unusually electrical, mechanical and thermal properties[13-16] and hence is an ideal component to fabricate composites for improving their performance. To take advantages of the extraordinary properties of CNTs it is important to align CNTs in the composites. Here we report a method of alignment of CNTs in the CNT/MgB2 superconductor composite wires through a readily scalable drawing technique. The aligned CNT doped MgB2 wires show an enhancement in magnetic Jc(H) by more than an order of magnitude in high magnetic fields, compared to the undoped ones. The CNTs have also significantly enhanced the heat transfer and dissipation. CNTs have been used mainly in structural materials, but here the advantage of their use in functional composites is shown and this has wider ramifications for other functional materials.

cond-mat.supr-con↗

arXiv2006

Study of $B_{s}\to πρ$ decays in the perturbative QCD approach

In this note, we calculate the branching ratio and CP asymmetry parameters of $B_s\toπρ$ in the framework of perturbative QCD approach based on $k_T$ factorization. This decay can occur only via annihilation diagrams in the Standard Model. We find that (a)the charge averaged $Br(B_s\toπ^{+}ρ^{-}+π^{-}ρ^{+})$ is about $(9-12)\times10^{-7}$; $Br(B_s\toπ^{0}ρ^{0}) \simeq 4\times10^{-7}$; and (b) there are sizable CP asymmetries in the processes, which can be tested in the near future Large Hadron Collider beauty experiments (LHC-b) at CERN or BTeV experiments at Fermilab.

hep-ph↗

arXiv2006

Branching Ratio and Polarization of $B\toρ(ω)ρ(ω)$ Decays in Perturbative QCD Approach

In this work, we calculated the branching ratios, polarization fractions and CP asymmetry of decay modes $B\toρ(ω)ρ(ω)$ in the Perturbative QCD approach, which is based on $\mathbf{k}_T$ factorization. After calculation, we find the the branching ratios of $B^0 \to ρ^+ ρ^-$, $B^+ \to ρ^+ ρ^0$ and $B^+ \to ρ^+ ω$ are at the order of $10^{-5}$, and their longitudinal polarization fractions are more than 90%. The above results agree with BarBar's measurements. We also predict the branching ratios and polarizations of $B^0 \to ρ^0 ρ^0$, $B^0 \to ρ^0 ω$ and $B^0 \to ωω$, which will be measured in future. We predicted the CP asymmetry of $B^0 \to ρ^+ ρ^-$ and $B^+ \to ρ^+ ρ^0$, which will play important role in determining angle $α$.

hep-ph↗

arXiv2005

Rare decays of B-> J/ψD^() and B->η_c D^()in pQCD Approach

Motivated by the recent measurement of the upper limit of ${B}^0 \to J/ψD$ branching ratio, which is important in accounting for the soft $J/ψ$ production in B decays, we investigate ${B}^0 \to J/ψD^{(\star)}$ and $η_c D^{(\star)}$ decays in perturbative QCD approach based on $k_T$ factorization. Being pure annihilation (W-exchange) decays, these branching ratios are estimated to be at the order of $10^{-5} \sim 10^{-7}$, which are just at the corner of being observable at the $B$ factories. The measurements of these decay channels may help us to understand the QCD dynamics in the corresponding energy scale, especially the reliability of pQCD approach to these processes.

hep-ph↗

arXiv2005

Branching ratio and CP violation of $B_{s}\to πK$ decays in the perturbative QCD approach

In the framework of perturbative QCD approach, we calculate the branching ratio and CP asymmetry for $B_{s}^0(\bar{B}_{s}) \to π^{\pm} K^\mp$ and $B_{s}(\bar{B}_{s})\to π^{0}\bar{K}^{0}(K^{0})$ decays. Besides the usual factorizable diagrams, both non-factorizable and annihilation type contributions are taken into account. We find that (a) the branching ratio of $B_{s}^0(\bar{B}_{s}) \to π^{\pm} K^\mp$ is about $(6-10) \times 10^{-6}$; $Br(B_{s}(\bar{B}_{s})\to π^{0}\bar{K}^{0}(K^{0}))$ about $ (1-3) \times 10^{-7}$; and (b) there are large CP asymmetries in the two processes, which can be tested in the near future LHC-b experiments at CERN and BTeV experiments at Fermilab.

hep-ph↗

arXiv2005

Quantum State Transfer Characterized by Mode Entanglement

We study the quantum state transfer (QST) of a class of tight-bonding Bloch electron systems with mirror symmetry by considering the mode entanglement. Some rigorous results are obtained to reveal the intrinsic relationship between the fidelity of QST and the mirror mode concurrence (MMC), which is defined to measure the mode entanglement with a certain spatial symmetry and is just the overlap of a proper wave function with its mirror image. A complementarity is discovered as the maximum fidelity is accompanied by a minimum of MMC. And at the instant, which is just half of the characteristic time required to accomplish a perfect QST, the MMC can reach its maximum value one. A large class of perfect QST models with a certain spectrum structure are discovered to support our analytical results.

quant-ph↗

arXiv2005

Branching ratio of rare decay $B^0(B_s)\to γν\barν$

The three-body decay $B^0(B_s)\to γν\barν$ can occur via penguin and box diagrams in the standard model (SM). These channels are useful to determine the decay constants $f_B$ ($f_{B_s}$) and $B$ ($B_s$) meson wave function. Using the B meson wave function determined in hadronic $B (B_s)$ decays, we calculate and get the branching ratio of order $10^{-9}$ and $10^{-8}$ for $B^0$ and $B_s$ decay, respectively. They agree with previous calculations.

hep-ph↗

arXiv2005

Perfect transfer of many-particle quantum state via high-dimensional systems with spectrum-matched symmetry

The quantum state transmission (QST) through the medium of high-dimensional many-particle system is studied with a symmetry analysis. We discover that, if the spectrum matches the symmetry of a fermion or boson system in a certain fashion, a perfect quantum state transfer can be implemented without any operation on the medium. Based on this observation the well-established results for the QST via quantum spin chains can be generalized to the high-dimensional many-particle systems with pre-engineered nearest neighbor (NN) hopping constants. By investigating a simple but realistic near half-filled tight-binding fermion system with uniform NN hopping integral, we show that an arbitrary many-particle state near the fermi surface can be perfectly transferred to its translational counterpart.

quant-ph↗

arXiv2005

Characterizing entanglement by momentum-jump in the frustrated Heisenberg ring at quantum phase transition

We study the pairwise concurrences, a measure of entanglement, of the ground states for the frustrated Heisenberg ring to explore the relation between entanglement and quantum phase transition associated with the momentum jump. The groundstate concurrences between any two sites are obtained analytically and numerically. It shows that the summation of all possible pairwise concurrences is an appropriate candidate to depict the phase transition. We also investigate the role that the momentum takes in the jump of concurrence at the critical points. We find that an abrupt momentum change rusults in the maximal concurrence difference of two degenerate ground states.

quant-ph↗

arXiv2004

Rare Decays $B^0 \to D_s^{()+} D_s^{()-}$ and $B_s^0 \to D^{()+} D^{()-}$ in Perturbative QCD Approach

In decay modes $B^0 \to D_s^{(*)+} D_s^{(*)-}$ and $B_s^0 \to D^{(*)+} D^{(*)-}$, none of quarks in final states is the same as one of $B$ meson. They can occur only via annihilation diagrams in the Standard Model. In the heavy quark limit, we try to calculate the branching ratios of these decays in perturbative QCD approach without considering the soft final state interaction. We found branching ratios of $B^0 \to D_s^{(*)+} D_s^{(*)-}$ are at the order of $ 10^{-5}$, and branching ratios of $B_s^0 \to D^{(*)+} D^{(*)-}$ are of $10^{-3}$. Those decay modes will be measured in $B$ factories and LHC-b experiments.

hep-ph↗

arXiv2004

Quantum state transfer via the ferromagnetic chain in a spatially modulated field

We show that a perfect quantum state transmission can be realized through a spin chain possessing a commensurate structure of energy spectrum, which is matched with the corresponding parity. As an exposition of the mirror inversion symmetry discovered by Albanese et. al (quant-ph/0405029), the parity matched the commensurability of energy spectra help us to present the novel pre-engineered spin systems for quantum information transmission. Based on the these theoretical analysis, we propose a protocol of near-perfect quantum state transfer by using a ferromagnetic Heisenberg chain with uniform coupling constant, but an external parabolic magnetic field. The numerical results shows that the initial Gaussian wave packet in this system with optimal field distribution can be reshaped near-perfectly over a longer distance.

quant-ph↗

arXiv2004

Branching ratio and CP asymmetry of $B_s \to π^+ π^-$ decays in the perturbative QCD approach

In this paper, we calculate the decay rate and CP asymmetry of the $B_s \to π^+π^-$ decay in perturbative QCD approach with Sudakov resummation. Since none of the quarks in final states is the same as those of the initial $B_s$ meson, this decay can occur only via annihilation diagrams in the standard model. Besides the current-current operators, the contributions from the QCD and electroweak penguin operators are also taken into account. We find that (a) the branching ratio is about $4 \times 10^{-7}$; (b) the penguin diagrams dominate the total contribution; and (c) the direct CP asymmetry is small in size: no more than $3% $; but the mixing-induced CP asymmetry can be as large as ten percent testable in the near future LHC-b experiments.

hep-ph↗