Pole analysis on the hadron spectroscopy of Λb→J/ΨpK−\Lambda_b\to J/\Psi p K^-

In this paper we study the $J/\Psi p$ spectroscopy in the process of $\Lambda_b\to J/\Psi p K^-$. The final state interactions of coupled channel $J/\Psi p$ ~-~ $\bar{D} \Sigma_c$~-~$\bar{D}^{*} \Sigma_c$ are constructed based on K-matrix with the Chew-Mandelstam function. We build the $\Lambda_b\to J/\Psi p K^-$ amplitude according to the Au-Morgan-Pennington method. The event shape is fitted and the decay width of $\Lambda_b\to J/\Psi p K^-$ is used to constrain the parameters, too. With the amplitudes we extract out the poles and their residues. Our amplitude and pole analysis suggest that the $P_c(4312)$ should be $\bar{D}\Sigma_c$ molecule, the $P_c(4440)$ could be an S-wave compact pentaquark state, and the structure around $P_c(4457)$ is caused by the cusp effect. The future experimental measurement of the decays of $\Lambda_b\to \bar{D}\Sigma_c K^-$ and $\Lambda_b\to \bar{D}^*\Sigma_c K^-$ would further help to study the nature of these resonances.Comment: updated to the published versio

Measurement of Grüneisen parameter of tissue by photoacoustic spectrometry

The Grüneisen parameter of tissue is a constitutive parameter in photoacoustic tomography. Here, we applied photoacoustic spectrometry (PAS) to directly measure the Grüneisen parameter. In our PAS system, laser pulses at wavelengths between 460 and 1600 nm were delivered to tissue samples, and photoacoustic signals were detected by a 20 MHz flat water-immersion ultrasonic transducer. By fitting photoacoustic spectra to light absorption spectra, we found that the Grüneisen parameter was 0.73 for porcine subcutaneous fat tissue, and 0.15 for oxygenated bovine red blood cells at room temperature (24°C)