Faddeev calculation of pentaquark Θ+\Theta^+ in the Nambu-Jona-Lasinio model-based diquark picture

A Bethe-Salpeter-Faddeev (BSF) calculation is performed for the pentaquark $\Theta^+$ in the diquark picture of Jaffe and Wilczek in which $\Theta^+$ is a diquark-diquark-${\bar s}$ three-body system. Nambu-Jona-Lasinio (NJL) model is used to calculate the lowest order diagrams in the two-body scatterings of ${\bar s}D$ and $D D$. With the use of coupling constants determined from the meson sector, we find that ${\bar s}D$ interaction is attractive in s-wave while $DD$ interaction is repulsive in p-wave. With only the lowest three-body channel considered, we do not find a bound $\frac 12^+$ pentaquark state. Instead, a bound pentaquark $\Theta^+$ with $\frac 12^-$ is obtained with a unphysically strong vector mesonic coupling constants.Comment: 22 pages, 11 figures, accepted version in Phys. Rev. C. Summary of main changes/corrections: 1. "which only holds at tree level" below the eq. (23) is added. 2. In the last paragraph of p.23 we added a remark that the coupling constant obtained from Lambda mass is different from the estimate as obtained from the meson spectru

Energy scale independence of Koide's relation for quark and lepton masses

Koide's mass relation of charged leptons has been extended to quarks and neutrinos, and we prove here that this relation is independent of energy scale in a huge energy range from $1 {GeV}$ to $2\times10^{16} {GeV}$. By using the parameters $k_u$, $k_d$ and $k_{\nu}$ to describe the deviations of quarks and neutrinos from the exact Koide's relation, we also check the quark-lepton complementarity of masses such as $k_{l}+k_{d} \approx k_{\nu}+k_{u} \approx 2$, and show that it is also independent (or insensitive) of energy scale.Comment: 16 Latex pages, 2 figures, final version to appear in PR

Joint measurement of multiple noncommuting parameters

Although quantum metrology allows us to make precision measurements beyond the standard quantum limit, it mostly works on the measurement of only one observable due to the Heisenberg uncertainty relation on the measurement precision of noncommuting observables for one system. In this paper, we study the schemes of joint measurement of multiple observables which do not commute with each other using the quantum entanglement between two systems. We focus on analyzing the performance of a SU(1,1) nonlinear interferometer on fulfilling the task of joint measurement. The results show that the information encoded in multiple noncommuting observables on an optical field can be simultaneously measured with a signal-to-noise ratio higher than the standard quantum limit, and the ultimate limit of each observable is still the Heisenberg limit. Moreover, we find a resource conservation rule for the joint measurement

Penta-hepta defect chaos in a model for rotating hexagonal convection

In a model for rotating non-Boussinesq convection with mean flow we identify a regime of spatio-temporal chaos that is based on a hexagonal planform and is sustained by the {\it induced nucleation} of dislocations by penta-hepta defects. The probability distribution function for the number of defects deviates substantially from the usually observed Poisson-type distribution. It implies strong correlations between the defects inthe form of density-dependent creation and annihilation rates of defects. We extract these rates from the distribution function and also directly from the defect dynamics.Comment: 4 pages, 5 figures, submitted to PR

Helical motions in the jet of blazar 1156+295

The blazar 1156+295 was observed by VLBA and EVN + MERLIN at 5 GHz in June 1996 and February 1997 respectively. The results show that the jet of the source has structural oscillations on the milliarcsecond scale and turns through a large angle to the direction of the arcsecond-scale extension. A helical jet model can explain most of the observed properties of the radio structure in 1156+295.Comment: 6 pages, 2 figures, to appear in New Astronomy Reviews (EVN/JIVE Symposium No. 4, special issue

Vector-pseudoscalar two-meson distribution amplitudes in three-body BB meson decays

We study three-body nonleptonic decays $B\to VVP$ by introducing two-meson distribution amplitudes for the vector-pseudoscalar pair, such that the analysis is simplified into the one for two-body decays. The twist-2 and twist-3 $\phi K$ two-meson distribution amplitudes, associated with longitudinally and transversely polarized $\phi$ mesons, are constrained by the experimental data of the $\tau\to\phi K\nu$ and $B\to\phi K\gamma$ branching ratios. We then predict the $B\to\phi K\gamma$ and $B\to\phi\phi K$ decay spectra in the $\phi K$ invariant mass. Since the resonant contribution in the $\phi K$ channel is negligible, the above decay spectra provide a clean test for the application of two-meson distribution amplitudes to three-body $B$ meson decays.Comment: 9 pages, 1 figure, Revtex4, version to appear in PR

Phase Change Observed in Ultrathin Ba0.5Sr0.5TiO3 Films by in-situ Resonant Photoemission Spectroscopy

Epitaxial Ba0.5Sr0.5TiO3 thin films were prepared on Nb-doped SrTiO3 (100)substrates by the pulsed laser deposition technique, and were studied by measuring the Ti 2p - 3d resonant photoemission spectra in the valence-band region as a function of film thickness, both at room temperature and low temperature. Our results demonstrated an abrupt variation in the spectral structures between 2.8 nm (~7 monolayers) and 2.0 nm (~5 monolayers) Ba0.5Sr0.5TiO3 films, suggesting that there exists a critical thickness for phase change in the range of 2.0 nm to 2.8 nm. This may be ascribed mainly to the intrinsic size effects.Comment: 13 pages, 4 figure

Puzzles in BB physics

I discuss some puzzles observed in exclusive $B$ meson decays, concentrating on the large difference between the direct CP asymmetries in the $B^0\to \pi^\mp K^\pm$ and $B^\pm\to \pi^0 K^\pm$ modes, the large $B^0\to\pi^0\pi^0$ branching ratio, and the large deviation of the mixing-induced CP asymmetries in the $b\to sq\bar q$ penguins from those in the $b\to c\bar c s$ trees.Comment: 6 pages, 1 figure, talk presented at the 9th Workshop on High Energy Physics Phenomenology, Bhubaneswar, Orissa, India, Jan. 3-14, 2006; reference adde

Applying Technology to Improve Student Learning Outcomes in Dynamics Course

Motivating and stimulating students to learn material in required core engineering courses is difficult and yet essential in assuring student success. Traditional methods of teaching and learning need to be reconsidered and modified to meet student expectations and their continuously evolving ways of interaction with technology and social networks. Numerous faculty have been experimenting with various approaches which are taking advantages of both technology and student interaction with technology, with various degrees of success. In this paper authors present another comprehensive method applied in teaching/learning of core engineering mechanics course. It has been observed over a long period of time that Dynamics is one of the more difficult courses in the Mechanical Engineering and Technology programs where students are experiencing certain difficulty in mastering the material. Authors integrated technology into learning experiences in order to stimulate and motivate students to master the material, which proved to be very successful. It has been observed that new approach improved the final scores in the course as well as student satisfaction with this approach of presenting material as well as testing their understanding of the required material. The paper presents results from two years of teaching the course with the current approach, along with lessons learned from this experience

Calibrating the dice loss to handle neural network overconfidence for biomedical image segmentation

The Dice similarity coefficient (DSC) is both a widely used metric and loss function for biomedical image segmentation due to its robustness to class imbalance. However, it is well known that the DSC loss is poorly calibrated, resulting in overconfident predictions that cannot be usefully interpreted in biomedical and clinical practice. Performance is often the only metric used to evaluate segmentations produced by deep neural networks, and calibration is often neglected. However, calibration is important for translation into biomedical and clinical practice, providing crucial contextual information to model predictions for interpretation by scientists and clinicians. In this study, we provide a simple yet effective extension of the DSC loss, named the DSC++ loss, that selectively modulates the penalty associated with overconfident, incorrect predictions. As a standalone loss function, the DSC++ loss achieves significantly improved calibration over the conventional DSC loss across six well-validated open-source biomedical imaging datasets, including both 2D binary and 3D multi-class segmentation tasks. Similarly, we observe significantly improved calibration when integrating the DSC++ loss into four DSC-based loss functions. Finally, we use softmax thresholding to illustrate that well calibrated outputs enable tailoring of recall-precision bias, which is an important post-processing technique to adapt the model predictions to suit the biomedical or clinical task. The DSC++ loss overcomes the major limitation of the DSC loss, providing a suitable loss function for training deep learning segmentation models for use in biomedical and clinical practice. Source code is available at https://github.com/mlyg/DicePlusPlus