arXiv subjects

Cong-Feng Qiao

Publications and source records attributed to Cong-Feng Qiao.

At least 145 records · Page 8Linked to original sources

arXiv2014

Finding the $0^{--}$ Glueball

With appropriate interpolating currents the mass spectrum of $0^{--}$ oddball is obtained in the framework of QCD Sum Rules (QCDSR). We find there are two stable oddballs with masses of $3.81 \pm 0.12 \, \text{GeV}$ and $4.33 \pm 0.13 \, \text{GeV}$, and analyze their possible production and decay modes in experiments. Noticing that these $0^{--}$ oddballs with unconventional quantum number are attainable in BESIII, BELLEII, PANDA, Super-B and LHCb experiments, we believe the long search elusive glueball could be measured shortly.

hep-ph↗

arXiv2014

Molecular states with hidden charm and strange in QCD Sum Rules

This work uses the QCD Sum Rules to study the masses of the $D_s \bar{D}_s^*$ and $D_s^* \bar{D}_s^*$ molecular states with quantum numbers $J^{PC} = 1^{+-}$. Interpolating currents with definite C-parity are employed, and the contributions up to dimension eight in the Operator Product Expansion (OPE) are taken into account. The results indicate that two hidden strange charmonium-like states may exist in the energy ranges of $3.83 \sim 4.13 $ GeV and $4.22 \sim 4.54 $ GeV, respectively. The hidden strange charmonium-like states predicted in this work may be accessible in future experiments, e.g. BESIII, BelleII and SuperB. Possible decay modes, which may be useful in further research, are predicted.

hep-ph↗

arXiv2014

Synchronous concentration and purification schemes of arbitrary unknown hyperentangled mixed states

We present two efficient schemes which can simultaneously accomplish hyperentanglement concentration and purification for two-photon four-qubit systems in an unknown partially hyperentangled mixed states. The first can correct errors in the polarization entanglement and extract maximal hyperentanglement in polarization and spatial mode with additional partial frequency entanglement. The second uses additional maximal frequency entanglement to purify and concentrate hyperentanglement in polarization and spatial mode deterministically. Both of the two schemes are only based on existing optical devices and cross-Kerr nonlinearities.

quant-ph↗

arXiv2014

NLO corrections to $χ_{bJ}$ to two-$J/ψ$ exclusive decay processes

The next-to-leading order QCD corrections for $χ_{bJ}$, the p-wave bottomonium, to $J/ψ$ pair decay processes are evaluated utilizing NRQCD factorization formalism. The scale dependence of $χ_{b2}\rightarrow J/ψJ/ψ$ process is depressed with NLO corrections, and hence the uncertainties in the leading order results are greatly reduced. The total branch ratios are found to be the order of $10^{-5}$ for all three $χ_{bJ}\rightarrow J/ψJ/ψ$ processes, indicating that they are observable in the LHC and super-B experiments.

hep-ph↗

arXiv2014

Understanding the cross section of $e^+e^-\to ηJ/ψ$ process via nonrelativistic QCD

Motivated by the large cross section of $e^+e^-\to ηJ/ψ$ process measured by the BESIII and Belle Collaborations recently, we evaluate this process at $\mathcal{O}(α_s^4)$ accuracy in the framework of nonrelativistic QCD. We find that the cross section at the center-of-mass energy $\sqrt{s}=4.009$ {GeV} is $34.6\mathrm{pb}$, which is consistent with the BESIII data. The comparison with the Belle data in the region from $4.0\ \mathrm{GeV}$ to $5.3\ \mathrm{GeV}$ is also presented. Concerning the $η$ and $η^\prime$ mixing and the potential gluonium component of $η^\prime$, we also estimate the rate of $e^+e^-\to η^\prime J/ψ$ process, which can be checked within the updated Belle data.

hep-ph↗

arXiv2014

Interpretation of $Z_c(4025)$ as the Hidden Charm Tetraquark States via QCD Sum Rules

By using QCD Sum Rules, we found that the charged hidden charm tetraquark $[c u][\bar{c} \bar{d}]$ states with $ J^P = 1^-$ and $ 2^+$, which are possible quantum numbers of the newly observed charmonium-like resonance $Z_c(4025)$, have masses of $m_{1^-}^c = (4.54 \pm 0.20) \, \text{GeV}$ and $m_{2^+}^c = (4.04 \pm 0.19) \, \text{GeV}$. The contributions up to dimension eight in the Operator Product Expansion (OPE) were taken into account in the calculation. The tetraquark mass of $J^{P} = 2^{+}$ state was consistent with the experimental data of $Z_c(4025)$, suggesting the $Z_c(4025)$ state possessing the quantum number of $J^P = 2^+$. Extending to the b-quark sector, the corresponding tetraquark masses $m_{1^-}^b = (10.97 \pm 0.25) \, \text{GeV}$ and $m_{2^+}^b = (10.35 \pm 0.25) \, \text{GeV}$ were obtained, which are testable in future B-factories.

hep-ph↗

arXiv2014

Search for $W^\prime$ signal via $tW^\prime$ associated production at LHC

A variety of new physics models predict the existence of extra charged gauge bosons ($W^\prime$). It is verified that $W^\prime$ and top quark associated production is a promising process to search for $W^\prime$ signal at the LHC. We study the collider signatures of multi-jets$+$lepton$+\met$ by reconstructing the $tW'$ intermediate state through the decay modes of $W^\prime \to tb$, $W^\prime \to q \bar q'$ and $W^\prime \to l ν$ respectively. An angular distribution related to charged lepton and top quark moving direction is provided to distinguish alternative left-handed or right-handed chiral couplings of $W^\prime$ to quarks in the hadronic decay modes. The superiority on the search of $W^\prime$ is demonstrated in the leptonic decay channel for the left-handed type interaction, which is forbidden for the right-handed type interaction in the most theories. To be more realistic, the relevant standard model backgrounds are simulated. We adopt various kinematic cuts to suppress the backgrounds and collect the integral luminosity needed for the corresponding process detected at the LHC with $3σ$ sensitivity. We also provide a forward-backward asymmetry which is related to the chirality of $W^\prime$. The successive studies can shed light on the potential searching for $W^\prime$ signal as well as distinguishing typical new physics models.

hep-ph↗

arXiv2014

Quantum Entanglement of Neutrino Pairs

It is practically shown that a pair of neutrinos from tau decay can form a flavor entangled state. With this kind of state we show that the locality constrains imposed by Bell inequality are violated by the quantum mechanics, and an experimental test of this effect is feasible within the earth's length scale. Theoretically, the quantum entanglement of neutrino pairs can be employed to the use of long distance cryptography distribution in a protocol similar to the BB84.

quant-ph↗

arXiv2014

Ascertaining the Uncertainty Relations via Quantum Correlations

We propose a new scheme to express the uncertainty principle in form of inequality of the bipartite correlation functions for a given multipartite state, which provides an experimentally feasible and model-independent way to verify various uncertainty and measurement disturbance relations. By virtue of this scheme the implementation of experimental measurement on the measurement disturbance relation to a variety of physical systems becomes practical. The inequality in turn also imposes a constraint on the strength of correlation, i.e. it determines the maximum value of the correlation function for two-body system and a monogamy relation of the bipartite correlation functions for multipartite system.

quant-ph↗

arXiv2013

$B_c$ Exclusive Decays to Charmonium and a Light Meson at Next-to-Leading Order Accuracy

In this paper the next-to-leading order (NLO) corrections to $B_c$ meson exclusive decays to S-wave charmonia and light pseudoscalar or vector mesons, i.e. $π$, $K$, $ρ$, and $K^*$, are performed within non-relativistic (NR) QCD approach. The non-factorizable contribution is included, which is absent in traditional naive factorization (NF). And the theoretical uncertainties for their branching ratios are reduced compared with that of direct tree level calculation. Numerical results show that NLO QCD corrections markedly enhance the branching ratio with a K factor of 1.75 for $B_{c}^{\pm}\to η_{c} π^{\pm}$ and 1.31 for $B_{c}^{\pm}\to J/ψπ^{\pm}$. In order to investigate the asymptotic behavior, the analytic form is obtained in the heavy quark limit, i.e. $m_b \to \infty$. We note that annihilation topologies contribute trivia in this limit, and the corrections at leading order in $z= m_c/m_b$ expansion come from form factors and hard spectator interactions. At last, some related phenomenologies are also discussed.

hep-ph↗

arXiv2013

Reconstructing the 125 GeV SM Higgs Boson Through $\ell\bar{\ell}γ$

To ascertain the new boson with mass near 125 {GeV} observed recently by ATLAS and CMS Collaborations to be the Standard Model Higgs, and to determine its intrinsic properties, more measurements on its various decay channels are still necessary. In this work we reanalyze the processes of the Standard Model Higgs radiative decays to lepton pairs. We find that when photon and leptons are hard, that is possessing energies larger than 1 {GeV}, the branching fractions of $H\rightarrow \ell\bar{\ell}γ(\ell=e~or~μ)$ processes are about two-thirds of the $H\rightarrowμ^+μ^-$ process. Since the lepton-pair yields of the radiative processes mainly come from the Z-boson conversion, which will greatly suppress the backgrounds, we believe the signal should be observable in presently accumulated data or in the next run of the LHC experiment, provided the Standard Model Higgs is indeed light.

hep-ph↗

arXiv2013

Baryonium

In the framework of the heavy baryon perturbation theory, in which the two-pion exchange is considered, the physical properties of heavy-baryon-anti-heavy-baryon systems are revisited. The potentials between heavy-baryon and anti-heavy-baryon are extracted in a holonomic form. Based on the extracted potentials, the s-wave scattering phase shifts and scattering lengths of $Λ_c$-$\barΛ_c$ and $Σ_c$-$\barΣ_c$ are calculated. From these scattering features, it is found that the $Λ_c$-$\barΛ_c$ system can be bound only when the value of the coupling constant $g_2$ is larger than that from the decay data of the $Σ_c(Σ_c^*) \to Λ_c π$ process. The binding condition for the $Σ_c$-$\barΣ_c$ system is also examined. The binding possibilities of these systems deduced from the scattering calculations are also checked by the bound state calculation and the binding energies are obtained if the system can be really bound. The binding possibility of the $Λ_b$-$\barΛ_b$ system is investigated as well.

hep-ph↗

arXiv2013

Generation of Einstein-Podolsky-Rosen State via Earth's Gravitational Field

Although various physical systems have been explored to produce entangled states involving electromagnetic, strong, and weak interactions, the gravity has not yet been touched in practical entanglement generation. Here, we propose an experimentally feasible scheme for generating spin entangled neutron pairs via the Earth's gravitational field, whose productivity can be one pair in every few seconds with the current technology. The scheme is realized by passing two neutrons through a specific rectangular cavity, where the gravity adjusts the neutrons into entangled state. This provides a simple and practical way for the implementation of the test of quantum nonlocality and statistics in gravitational field.

quant-ph↗

arXiv2013

Classification of Arbitrary Multipartite Entangled States under Local Unitary Equivalence

We propose a practical method for finding the canonical forms of arbitrary dimensional multipartite entangled states, either pure or mixed. By extending the technique developed in one of our recent works, the canonical forms for the mixed $N$-partite entangled states are constructed where they have inherited local unitary symmetries from their corresponding $N+1$ pure state counterparts. A systematic scheme to express the local symmetries of the canonical form is also presented, which provides a feasible way of verifying the local unitary equivalence for two multipartite entangled states.

quant-ph↗

arXiv2013

Estimation of Semileptonic Decays of $B_c$ Meson to S-wave Charmonia with NRQCD

We study the semileptonic differential decay rates of $B_c$ meson to S-wave charmonia, $η_c$ and $J/Ψ$, at the next-to-leading order accuracy in the framework of NRQCD. In the heavy quark limit, $m_b \to \infty$, we obtain analytically the asymptotic expression for the ratio of NLO form factor to LO form factor. Numerical results show that the convergence of the ratio is perfect. At the maximum recoil region, we analyze the differential decay rates in detail with various input parameters and polarizations of $J/ψ$, which can now be checked in the LHCb experiment. Phenomenologically, the form factors are extrapolated to the minimal recoil region, and then the $B_c$ to charmonium semileptonic decay rates are estimated.

hep-ph↗

arXiv2012

P-wave Quarkonium Decays to Meson Pairs

The processes of P-wave Quarkonium exclusive decays to two mesons are investigated, in which the final state vector mesons with various polarizations are considered separately. In the calculation, the initial heavy quarkonia are treated in the framework of non-relativistic quantum chromodynamics, whereas for light mesons, the light cone distribution amplitudes up to twist-3 are employed. It turns out that the higher twist contribution is significant and provides a possible explanation for the observation of the hadron helicity selection rule violated processes $χ_{c1}\rightarrow ϕϕ,ωω$ by the BESIII collaboration in recently. We also evaluate the $χ_{b1}\to J/ψJ/ψ$ process and find that its branching ratio is big enough to be measured at the B-factories.

hep-ph↗

arXiv2012

Proposal for a new scheme for producing a two-photon, high dimensional hyperentangled state

We propose an experimentally feasible scheme for generating a two $2\times4\times4$ dimensional photons hyperentangled state, entangled in polarization, frequency and spatial mode. This scheme is mainly based on a parametric down-conversion source and cross-Kerr nonlinearities, which avoids the complicated uncertain post-selection. Our method can be easily expanded to the production of hyperentangled states with more photons in multidimensions. Hence the expectation for vast quantities of information in quantum information processing will possibly come true. Finally, we put forward a realizable quantum key distribution (QKD) protocol based on the high dimensional hyperentangled state.

quant-ph↗

arXiv2012

$J/ψ$ Pair Production at the Tevatron with $\sqrt{s}=1.96~\mathrm{TeV}

We revisit the $J/ψ$ pair production issue at the Fermilab Tevatron Run II with the center-of-mass energy $\sqrt{s}=1.96 \mathrm{TeV}$. Both color-singlet and -octet production mechanisms are considered. Our result shows that the transverse momentum($p_T$) scaling behaviors of double $J/ψ$ differential cross sections in color-singlet and -octet deviate distinctively from each other while $p_T$ is larger than $8 \mathrm{GeV}$, and with the luminosity of ${5 \mathrm{fb^{-1}}}$ the $J/ψ$ pair events from color-singlet scheme are substantially measurable in Tevatron experiments, even with certain lower transverse momentum cut. Hence the Tevatron is still possibly a platform to check the heavy quarkonium production mechanism.

hep-ph↗