[en] In the framework of the perturbative QCD, the two-fold differential cross section d²σ/dxsub(T)dxsub(L) of the reaction γ+p→2γ+X and its two backgrounds (γ+p→γ+q(q-bar)+X, γ+p→γ+q(q-bar)+X) are calculated in c.m.s. The results show that, in a large range of (xsub(T), xsub(L)), the calculated reaction cross section can be measured in current laboratory condition. And due to the properties of this reaction, i.e., large Psub(T) photoproduction and direct photon pair emission, all of the backgrounds can be greatly suppressed. (author)

[en] We calculate the corss-section differences: (a) dσ(PP-bar → Jet + γ + X) - dσ(PP → Jet + γ + X) (b) dσ(PP-bar → 2γ + X) - dσ(PP → 2γ + X) (c) dσ(K^-P → Jet + γ + X) - dσ(K⁺P → Jet + γ + X) (d) dσ(K^-P → 2γ + X) - dσ(K⁺p → 2γ + X) (e) dσ(PP-bar → 2Jet + X) - dσ(PP → 2Jet + X), and find that they are ont affected by gluon and sea-quark distribution functions and various fragmentation functions. Comparing these results with the corresponding experimental data, one can accurately determine the ratio αsub(s)/α under the present experimental conditions

[en] In this paper we disscuse the physical aspect of cross-section differences Δ_AB^Cγ = dσ(AB → cγX) - dσ(AB → c-barγX) and give the simple rules to select the elementary subprocesses which contribute to cross-section differences. We bind a way to test the gluon distribution functions of hadrons through the measurement of cross-section difference or combination of cross-section differences in the large P_T process with direct photon emission. Moreover we obtain simple relations between each combination of cross-sections and the corresponding gluon distribution functions of proton, neutron, pion and kaon, which are expected to be tested in future experiments

[en] We analyse the jet-charge-cross section of following three reactions: p + p → γ + Jet + X, γ + p → 2Jets + X, γ + p → h + Jet + X, and present the methods respectively for testing gluon distribution function in proton, extracting the information of gluon jets and determining the fragmentation function of gluon

[en] Based on the jet-charge-cross section method, a practical scheme is worked out to test the photon structure function directly

[en] In the presence of the Hubbard interaction, graphene zigzag nanoribbons have spontaneous edge magnetism with anti-parallel configuration, whose amplitude can be tuned by a transversal electric field. As the electric field increases or decreases across a critical value, the edges are demagnetized or re-magnetized, respectively. A magnetic field at each edge determines the orientation of the re-magnetization. Thus, a combination of a slowly varying transversal electric field and magnetic field in monolayer graphene zigzag nanoribbons can drive the quantum system into a bistability loop. The same phenomenon can be induced in a bilayer/monolayer zigzag nanoribbon without the magnetic field, because the non-symmetry superexchange interaction controls the orientation of the re-magnetization. In this way, the quantum system is switched between ground state and quasi-stable excited state with different magnetism, band structures and conductance. This feature could be used to develop graphene-based spintronic nano-devices without magnetic field. (paper)

[en] The Chinese government has made many energy policies on coal, and coalmine methane (CMM) use. However, not all of these policies have effects or positive impacts. For example, it has been quite a few years since the national government made policies to encourage coalmine methane power to be sold to the grid. Practice showed that not any kilowatt of electricity was sold from a coalmine methane power plant to the grid in Sichuan and Guizhou Provinces as of December 2008. The objectives of this paper are to review and evaluate the Chinese government energy and climate policies that are related to coal and coalmine methane, analyze relevant policy barriers, and make recommendations to overcome these barriers and avoid policy failures. This paper provides the literature review, challenges, resources, policies and other updated information on China's CMM recovery and utilization. The paper concludes that China needs to further reform its energy and environment management system, engage provincial governments in CMM capture and use activities, and provide incentives to qualified engineers and skilled workers to work in remote coal mining areas. This paper transfers key messages to policy makers for them to make better CMM capture and use policies. (author)

[en] The Chinese government has made many energy policies on coal, and coalmine methane (CMM) use. However, not all of these policies have effects or positive impacts. For example, it has been quite a few years since the national government made policies to encourage coalmine methane power to be sold to the grid. Practice showed that not any kilowatt of electricity was sold from a coalmine methane power plant to the grid in Sichuan and Guizhou Provinces as of December 2008. The objectives of this paper are to review and evaluate the Chinese government energy and climate policies that are related to coal and coalmine methane, analyze relevant policy barriers, and make recommendations to overcome these barriers and avoid policy failures. This paper provides the literature review, challenges, resources, policies and other updated information on China's CMM recovery and utilization. The paper concludes that China needs to further reform its energy and environment management system, engage provincial governments in CMM capture and use activities, and provide incentives to qualified engineers and skilled workers to work in remote coal mining areas. This paper transfers key messages to policy makers for them to make better CMM capture and use policies.

[en] Topologically protected zero-line modes appear at the interface between two regions of the monolayer graphene in quantum anomalous Hall phase with different Chern number. In the presence of staggered sublattice potential, the band gaps of the two valleys become different, and the phase diagram defined by the Chern number has an additional regime of topologically trivial phase. The interface between the topologically trivial and non-trivial regions hosts zero-line mode in only one valley. By tuning the exchange field, three types of interface that host zero-line modes in selected valley(s) are formed. The nano-devices consisted of Y-shape junctions of the three types of interface exhibit the functions of valley splitting, merging or filtering for the incident currents. (paper)

[en] The two dimensional square lattice antiferromagnet with spin–orbit coupling and nonsymmorphic symmetry is recently found to be topological insulator (TI). We theoretically studied the Floquet states of the antiferromagnetic crystal with optical irradiation, which could be applicable in opto-spintronic. An optical irradiation with circular polarization induces topological phase transition into quantum Anomalous Hall phase with varying Chern number. At the phase boundaries, the Floquet systems could be semimetal with one, two or three band valleys. A linear polarized optical field induces effective antiferromagnetic exchange field, which change the phase regime of the TI. At the intersection of two phase boundaries, the bulk band structure is nearly flat along one of the high symmetry line in the first Brillouin zone, which result in large density of states near to the Fermi energy in bulk and nanoribbons. (paper)