Search for doubly heavy baryon via weak decays

Using the factorization approach and taking into account the final state interaction, we calculate the two body non-leptonic decays of doubly heavy baryons. After comparing the semi-leptonic decays and all possible hadronic decay channels, we found some channels with large branching ratios. Taking the detection efficiency into consideration, we suggest $\Xi_{cc}^{++}$ as the first search goal and $\Xi_{cc}^{++}\to \Lambda_c^+K^-\pi^+\pi^+$ and $\Xi_{cc}^{++}\to\Xi_{c}^{+}\pi^{+}$ as the golden discovery channels with $\Lambda_c^+$ reconstructed by $pK^-\pi^+$ and $\Xi_{c}^+ \to p K^- \pi^+$, respectively.Comment: 4 pages; to appear in the Proceedings of the 53rd Rencontres de Moriond QCD session of March 201

Correlation Measurement of an unknown state with Weak Coupling

Traditionally, quantum state correlation can be obtained with calculations on a state density matrix already known. Here, we propose a model with which correlations of unknown quantum states can be obtained. There are no needs of classical communication in the course of coupling, optimization and complicated calculations. All we need are weak coupling and ancillary systems. We detail the model on the state in which particles belong to the different owners. A concisely example is elaborated in the last part of this paper

Lower bound of local quantum uncertainty for high-dimensional bipartite quantum systems

Quantum correlations are of fundamental importance in quantum phenomena and quantum information processing studies. The measure of quantum correlations is one central issue. The recently proposed measure of quantum correlations, the local quantum uncertainty (LQU), satisfies the full physical requirements of a measure of quantum correlations. In this work, by using operator relaxation, a closed form lower bound of the LQU for arbitrary-dimensional bipartite quantum states is derived. We have compared the lower bound and the optimized LQU for several typical quantum states.Comment: We have revised the manuscript. Comments are welcom

Manipulation of atom-to-molecule conversion in a magnetic lattice

The atom-to-molecule conversion by the technique of optical Feshbach resonance in a magnetic lattice is studied in the mean-field approximation. For the case of shallow lattice, we give the dependence of the atom-to-molecule conversion efficiency on the tunnelling strength and the atomic interaction by taking a double-well as an example. We find that one can obtain a high atom-to-molecule conversion by tuning the tunnelling and interaction strengths of the system. For the case of deep lattice, we show that the existence of lattice can improve the atom-to-molecule conversion for certain initial states

Measurement of weak static magnetic fields with nitrogen-vacancy color center

We propose a strategy to measure weak static magnetic fields with nitrogen-vacancy color center in diamond. Inspired by avian magnetoreception models, we consider the feasibility of utilizing quantum coherence phenomena to measure weak static magnetic fields. Nitrogen-vacancy (NV) color centers are regarded as the ideal platform to study quantum sciences as a result of its long coherence time up to a millisecond timescale. In high-purity diamond, hyperfine interaction with 13C nuclear spins dominates the decoherence process. In this paper, we numerically simulate the decoherence process between 0 and +1 of the individual NV color center spin in 13C nuclear baths with various of magnitudes of external magnetic fields. By applying Hahn echo into the system, we obtain the coherence of NV color center spin as a function of total evolution time and magnetic field. Furthermore we obtain the high-accuracy relationship between the three decoherence-characteristic timescales, i.e. T_W, T_R, T_2, and magnetic field B. And we draw a conclusion that T_R has the highest sensitivity about magnetic field among the three time-scales. Thus, for a certain NV color center, T_R can be the scale for the magnitude of magnetic field, or rather, the component along the NV electronic spin axis. When measuring an unknown magnetic field, we adjust the NV axis to three mutually orthogonal directions respectively. By this means, we obtain the three components of the magnetic field and thus the magnitude and direction of the actual magnetic field. The accuracy could reach 60 nT/Hz^{1/2},and could be greatly improved by using an ensemble of NV color centers or diamond crystals purified with 12C atoms.Comment: 17 pages, 5 figures, 1 tabl

Exclusive BsB_s decays to the charmed mesons Ds+(1968,2317)D_s^+(1968,2317) in the standard model

The transition form factors of $\bar B_s^0\to D_{s}^+(2317)$ and $\bar B_s^0\to D_s^+(1968)$ at large recoil region are investigated in the light cone sum rules approach, where the heavy quark effective theory is adopted to describe the form factors at small recoil region. With the form factors obtained, we carry out a detailed analysis on both the semileptonic decays $\bar B_s^0\to D_s^+(1968,2317) l \bar{\nu}_l$ and nonleptonic decays $B_s \to D_s^+(1968,2317) M$ with $M$ being a light meson or a charmed meson under the factorization approach. Our results show that the branching fraction of $\bar B_s^0\to D_s^+(2317) \mu \bar{\nu}_\mu$ is around $2.3 \times 10^{-3}$, which should be detectable with ease at the Tevatron and LHC. It is also found that the branching fractions of $\bar B_s^0\to D_s^+(1968) l \bar{\nu}_l$ are almost one order larger than those of the corresponding $B_s^0\to D_s^+(2317) l \bar{\nu}_l$ decays. The consistency of predictions for $B_s \to D_s^+(1968,2317) L$ ($L$ denotes a light meson) in the factorization assumption and $k_T$ factorization also supports the success of color transparency mechanism in the color allowed decay modes. Most two-charmed meson decays of $B_s$ meson possess quite large branching ratios that are accessible in the experiments. These channels are of great importance to explore the hadronic structure of charmed mesons as well as the nonperturbative dynamics of QCD.Comment: 21 pages, 3 figure

Quantifying entanglement of arbitrary-dimensional multipartite pure states in terms of the singular values of coefficient matrices

The entanglement quantification and classification of multipartite quantum states are two important research fields in quantum information. In this work, we study the entanglement of arbitrary-dimensional multipartite pure states by looking at the averaged partial entropies of various bipartite partitions of the system, namely, the so-called Manhattan distance ($l_1$ norm) of averaged partial entropies (MAPE), and it is proved to be an entanglement measure for pure states. We connected the MAPE with the coefficient matrices, which are important tools in entanglement classification and reexpressed the MAPE for arbitrary-dimensional multipartite pure states by the nonzero singular values of the coefficient matrices. The entanglement properties of the $n$-qubit Dicke states, arbitrary-dimensional Greenberger-Horne-Zeilinger states, and $D_3^n$ states are investigated in terms of the MAPE, and the relation between the rank of the coefficient matrix and the degree of entanglement is demonstrated for symmetric states by two examples.Comment: 6 pages, 4 figures accepted for publication in PR

Descriptions of Carbon isotopes within relativistic Hartree-Fock-Bogoliubov theory

Within the relativistic Hartree-Fock-Bogoliubov (RHFB) theory, the structure properties of Carbon isotopes are systematically studied. In order to reproduce the experiment data, we take the finite-range Gogny D1S with a strength factor $f$ as the pairing force. The self-consistent RHFB calculations with density-dependent meson-nucleon couplings indicate the single-neutron halo structures in both $^{17}$C and $^{19}$C, whereas the two-neutron halo in $^{22}$C is not well supported. It is also found that close to the neutron drip line there exists distinct odd-even staggering on neutron radii, which is tightly related with the blocking effects and correspondingly the blocking effect plays a significant role in halo formation.Comment: 8 pages, 5 figures, 5 tabl

Phase transitions of the dimerized Kane-Mele model with/without the strong interaction

The dimerized Kane-Mele model with/without the strong interaction is studied using analytical methods. The boundary of the topological phase transition of the model without strong interaction is obtained. Our results show that the occurrence of the transition only depends on dimerized parameter . From the one-particle spectrum, we obtain the completed phase diagram including the quantum spin Hall (QSH) state and the topologically trivial insulator. Then, using different mean-field methods, we investigate the Mott transition and the magnetic transition of the strongly correlated dimerized Kane-Mele model. In the region between the two transitions, the topological Mott insulator (TMI) with characters of Mott insulators and topological phases may be the most interesting phase. In this work, effects of the hopping anisotropy and Hubbard interaction U on boundaries of the two transitions are observed in detail. The completed phase diagram of the dimerized Kane-Mele-Hubbard model is also obtained in this work. Quantum fluctuations have extremely important influences on a quantum system. However, investigations are under the framework of the mean field treatment in this work and the effects of fluctuations in this model will be discussed in the future.Comment: 18 pages, 6 figure

Quantum phase transition in an atom-molecule conversion system with atomic hopping

The quantum phase transition in an atom-molecule conversion system with atomic hopping between different hyperfine states is studied. In mean field approximation, we give the phase diagram whose phase boundary only depends on the atomic hopping strength and the atom-molecule energy detuning but not on the atomic interaction. Such a phase boundary is further confirmed by the fidelity of the ground state and the energy gap between the first-excited state and the ground one. In comparison to mean field approximation, we also study the quantum phase transition in full quantum method, where the phase boundary can be affected by the particle number of the system. Whereas, with the help of finite-size scaling behaviors of energy gap, fidelity susceptibility and the first-order derivative of entanglement entropy, we show that one can obtain the same phase boundary by the MFA and full quantum methods in the limit of $N\rightarrow \infty$. Additionally, our results show that the quantum phase transition can happens at the critical value of the atomic hopping strength even if the atom-molecule energy detuning is fixed on a certain value, which provides one a new way to control the quantum phase transition.Comment: 7 pages,6 figure