Landau Problem in Noncommutative Quantum Mechanics

The Landau problem in non-commutative quantum mechanics (NCQM) is studied. First by solving the Schr$\ddot{o}$dinger equations on noncommutative(NC) space we obtain the Landau energy levels and the energy correction that is caused by space-space noncommutativity. Then we discuss the noncommutative phase space case, namely, space-space and momentum-momentum non-commutative case, and we get the explicit expression of the Hamiltonian as well as the corresponding eigenfunctions and eigenvalues.Comment: 8 page

Crystallographic Orbifolds: Towards a Classification of Unitary Conformal Field Theories with Central Charge c = 2

We study the moduli space C^2 of unitary two-dimensional conformal field theories with central charge c=2. We construct all the 28 nonexceptional nonisolated irreducible components of C^2 that may be obtained by an orbifold procedure from toroidal theories. The parameter spaces and partition functions are calculated explicitly, and all multicritical points and lines are determined. We show that all but four of the 28 irreducible components of C^2 corresponding to nonexceptional orbifolds are directly or indirectly connected to the moduli space of toroidal theories in C^2. We relate our results to those by Dixon, Ginsparg, Harvey on the classification of c=3/2 superconformal field theories and thereby give geometric interpretations to all nonisolated orbifolds discussed there.Comment: 47 pages, spelling mistakes corrected; final version for JHE

Spin Hall effect on a noncommutative space

We study the spin-orbital interaction and the spin Hall effect(SHE) of an electron moving on a noncommutative space under the influence of a vector potential A. On a noncommutative space we find that the commutator between the vector potential A and the electric potential V_1(r) of lattice induces a new term which can be treated as an effective electric field, and the spin-Hall conductivity obtains some correction. In addition, the spin current as well as spin-Hall conductivity have distinct values in different direction. On a noncommutative space we derive the spin-depended electric current whose expectation value gives the spin Hall effect and spin Hall conductivity. We have defined a new parameter \varsigma=\rho\theta (\rho is electron concentration, \theta is noncommutative parameter) which can be measured experimentally. Our approach is based on the Foldy-Wouthuysen transformation which give a general Hamiltonian of a non-relativistic electron moving on a noncommutative space.Comment: 5 pages, references added, typos correcte

The Aharonov-Casher and scalar Aharonov-Bohm topological effects

We reexamine the topological and nonlocal natures of the Aharonov-Casher and scalar Aharonov-Bohm phase effects. The underlying U(1) gauge structure is exhibited explicitly. And the conditions for developing topological Aharonov-Casher and scalar Aharonov-Bohm phases are clarified. We analyse the arguments of M. Peshkin and H. J. Lipkin (Phys. Rev. Lett. 74, 2847(1995)) in detail and show that they are based on the wrong Hamiltonian which yields their conclusion incorrect.Comment: 4 pages, no figur

Covariant tensor formalism for partial wave analyses of ψ\psi decays into γBBˉ\gamma B\bar B, γγV\gamma\gamma V and ψ(2S)→γχc0,1,2\psi(2S)\to\gamma\chi_{c0,1,2} with χc0,1,2→KKˉπ+π−\chi_{c0,1,2}\to K\bar K \pi^+\pi^- and 2π+2π−2\pi^+2\pi^-

With accumulation of high statistics data at BES and CLEO-c, many new interesting channels can get enough statistics for partial wave analysis (PWA). Among them, $\psi \to \gamma p\bar p, \gamma\Lambda\bar \Lambda, \gamma\Sigma \bar\Sigma, \gamma\Xi\bar \Xi$ channels provide a good place for studying baryon-antibaryon interactions; the double radiative decays $\psi\to\gamma\gamma V$ with $V\equiv \rho,\omega,\phi$ have a potential to provide information on the flavor content of any meson resonances (R) with positive charge parity ($C=+$) and mass above 1 GeV through $\psi\to\gamma R \to\gamma\gamma V$; $\psi(2S)\to\gamma\chi_{c0,1,2}$ with $\chi_{c0,1,2}\to K\bar K \pi^+\pi^-$ and $2\pi^+2\pi^-$ decays are good processes to study $\chi_{cJ}$ charmonium decays. Using the covariant tensor formalism, here we provide theoretical PWA formulae for these channels.Comment: 20 page

The Orbifolds of N=2 Superconformal Theories with c=3

We construct Z_M, M= 2, 3, 4, 6 orbifold models of the N=2 superconformal field theories with central charge c=3. Then we check the description of the Z_3, Z_4 and Z_6 orbifolds by the N=2 superconformal Landau-Ginzburg models with c=3, by comparing the spectrum of chiral fields, in particular the Witten index Tr(-1)^F.Comment: 20 pages; typos corrected, references adde