Faddeev-Skyrme Model and Rational Maps

The Faddeev-Skyrme model, a modified O(3) nonlinear sigma model in three space dimensions, is known to admit topological solitons that are stabilized by the Hopf charge. The Faddeev-Skyrme model is also related to the low-energy limits of SU(2) Yang-Mills theory. Here, the model is reformulated into its gauge-equivalent expression, which turns out to be Skyrme-like. The solitonic solutions of this Skyrme-like model are analyzed by the rational map ansatz. The energy function and the Bogomolny-type lower bound of the energy are established. The generalized Faddeev-Skyrme model that originates from the infrared limits of SU(N) Yang-Mills theory is presented.Comment: 12 pages, LaTex, minor typo correcte

Constraints on spacetime anisotropy and Lorentz violation from the GRAAL experiment

The GRAAL experiment could constrain the variations of the speed of light. The anisotropy of the speed of light may imply that the spacetime is anisotropic. Finsler geometry is a reasonable candidate to deal with the spacetime anisotropy. In this paper, the Lorentz invariance violation (LIV) of the photon sector is investigated in the locally Minkowski spacetime. The locally Minkowski spacetime is a class of flat Finsler spacetime and refers a metric with the anisotropic departure from the Minkowski one. The LIV matrices used to fit the experimental data are represented in terms of these metric deviations. The GRAAL experiment constrains the spacetime anisotropy to be less than $10^{-14}$. In addition, we find that the simplest Finslerian photon sector could be viewed as a geometric representation of the photon sector in the minimal standard model extension (SME).Comment: 13 pages, 2 tables. Two typos are corrected in Table

BCVEGPY2.0: A upgrade version of the generator BCVEGPY with an addendum about hadroproduction of the PP-wave BcB_c states

The generator BCVEGPY is upgraded by adding the hadroproduction of the $P$-wave excited $B_c$ states (denoted by $B_{cJ,L=1}^*$ or by $h_{B_c}$ and $\chi_{B_c}$) and by improving some features of the original one as well. We denote it as BCVEGPY2.0. The $P$-wave production is also calculated by taking only the dominant gluon-gluon fusion mechanism (with the subprocess $gg\to B_{cJ,L=1}^*+\bar{c}+b$ being dominated) into account as that for $S$-wave. In order to make the addendum piece of the upgraded generator as compact as possible so as to increase its efficiency, we manipulate the amplitude as compact as possible with FDC (a software for generating Feynman diagrams and the algebra amplitudes, and for manipulating algebra formulae analytically etc) and certain simplification techniques. The correctness of the program is tested by checking the gauge invariance of the amplitude and by comparing the numerical results with the existent ones in the literature carefully.Comment: 21 page, 4 figure