Production of charged ρ\rho meson in bottom hadron charmed decays and the effect of the finite width correction of the ρ\rho meson

We calculate the branching ratio of a bottom hadron decaying into a charmed hadron and a charged $\rho$ meson within the QCD factorization approach. We consider the effect of the finite width correction of the $\rho$ meson. Our numerical calculation shows an obvious correction because of this effect. We find that the finite width effect of the $\rho$ meson reduces the branching ratios by about 9% to 11% for bottom meson decay channels: $B^+\to\bar{D^0}\rho^+$, $B^0\to D^-\rho^+$, and $B^0_s\to D^-_s\rho^+$, and increases the branching ratio by about 10% for $\Lambda_b^0\to\Lambda_c^+\rho^-$.Comment: 12 page

Study on experiment measurement method of braking force of muzzle brake for vibration analysis

The braking force of the muzzle brake affects not only the strength of the connection thread of the muzzle brake, but also the vibration response of the artillery structure. Due to the complex formation process of the braking force of the muzzle brake, the current theoretical calculation method is used to estimate. This paper presents an experimental measurement method for artillery force of muzzle brake, which describes the measurement principle and deduces the calculation formula. The small-caliber cannon with muzzle brake is selected as the test object. A verification shooting experiment is carried out to obtain the size of the artillery force of the muzzle brake. The measurement values of the artillery force are basically consistent with the theoretical ones. The measurement method and principle introduced in this paper can be applied in the actual artillery force measurement of the muzzle brake. In this paper, the strain measurement principle is used to complete the experimental test of the braking force of the muzzle brake. This paper innovatively proposes a new method for testing the braking force, which has the advantages of simple operation, no need to manufacture special tooling, and low cost

Long-Range Correlation of Electron Pairs in the Hubbard Model at Finite Temperatures in Three Dimensions

We show that in the translation invariant case and in the antiferromagnetic phase, the reduced density matrix $\rho _2$ has no off-diagonal long-range order of on-site electron pairs for the single-band Hubbard model on a cubic lattice away from half filling at finite temperatures both for the positive coupling and for the negative coupling. In these cases the model can not give a mechanism for the superconductivity caused by the condensation of on-site electron pairs and the nearest-neighbor electron pairs.Comment: 9 pages, Latex fil