Anti-charmed pentaquark from B decays

We explore the possibility of observing the anti-charmed pentaquark state from the $\Theta_c \bar{n} \pi^+$ decay of $B$ meson produced at $B$-factory experiments. We first show that the observed branching ratio of the $B^+$ to $\Lambda^-_c p \pi^+$, as well as its open histograms, can be remarkably well explained by assuming that the decay proceeds first through the $\pi^+ \bar{D}^0$ (or $\bar{D}^{*0}$) decay, whose branching ratios are known, and then through the subsequent decay of the virtual $\bar{D}^0$ or $\bar{D}^{*0}$ mesons to $\Lambda_c^- p$, whose strength are calculated using previously fit hadronic parameters. We then note that the $\Theta_c$ can be similarly produced when the virtual $\bar{D}^0$ or $\bar{D}^{*0}$ decay into an anti-nucleon and a $\Theta_c$. Combining the present theoretical estimates for the ratio $g_{D N \Lambda_c} / g_{D N \Theta_c} \sim 13$ and $g_{D^* N \Theta_c} \sim {1/3} g_{D N \Theta_c}$, we find that the anti-charmed pentaquark $\Theta_c$, which was predicted to be bound by several model calculations, can be produced via $B^+ \to \Theta_c \bar{n} \pi^+$, and be observed from the $B$-factory experiments through the weak decay of $\Theta_c \to p K^+ \pi^- \pi^-$.Comment: 4 pages, 4 figures, Revised version to be published in Physical Review Letter

Evaluation of floor vibrations induced by walking in reinforced concrete buildings

Floor vibrations induced by human walking were investigated in a reinforced concrete structure. Six experimental floor structures were built in laboratories with the same dimensions and boundary conditions. Subjective tests were performed to assess the vibration serviceability of the floor structures. First, the subjects were asked to walk across a floor and then to rate the intensity of the vibrations, acceptability, and serviceability of the floors. In the second part of the tests, the subjects were seated on a chair placed in the middle of the floor and asked to rate floor vibrations when the walker passed the subjects. Floor vibrations induced by human walking were analyzed using peak acceleration, root mean square (r.m.s.) acceleration, and the vibration dose value (VDV), and four weighting functions (Wb, Wk, Wg, and Wm) were applied. Significant differences in the measured floor vibration were found across the floor structures, larger floor vibration lead to greater perceived vibration intensity, lower acceptability and serviceability. The Wb and Wk were found to be more applicable than Wg and Wm to explain perception of floor vibration. It was observed that the impact noise induced by walking did not influence the evaluation of floor vibratio