Singly Cabibbo suppressed decays of Λc+\Lambda_{c}^+ with SU(3) flavor symmetry

We analyze the weak processes of anti-triplet charmed baryons decaying to octet baryons and mesons with the SU(3) flavor symmetry and topological quark diagram scheme. We study the decay branching ratios without neglecting the contributions from ${\cal O}(\overline{15})$ for the first time in the SU(3) flavor symmetry approach. The fitting results for the Cabibbo allowed and suppressed decays of $\Lambda_{c}^+$ are all consistent with the experimental data. We predict all singly Cabibbo suppressed decays. In particular, we find that ${\cal B}(\Lambda_c^+\to p \pi^0)=(1.3\pm0.7)\times 10^{-4}$, which is slightly below the current experimental upper limit of $2.7\times 10^{-4}$ and can be tested by the ongoing experiment at BESIII as well as the future one at Belle-II.Comment: 11 pages, 2 figure, revised version accepted by PL

Center of mass motion in bag model

Despite the great success on the mass spectra, the reputation of the bag model has been closely followed by the embarrassment from the center of mass motion. It leads to severe theoretical inconsistencies. For instance, the masses and the decay constants would no longer be independent of the momentum. In this work, we provide a systematical approach to resolve this problem. The meson decay constants as well as the baryon transition form factors can be computed consistently in our framework. Notably, the form factors in the neutron $\beta$ decays do not depend on any free parameters, and are determined to be $F^V_1 =1$ and $F^A_1 = 1.31$ or $F_1^A/F_1^V= 1.31$, which is close the experimental value of $F^A_1/F^V_1 = 1.27$. In addition, we find that ${\cal B} (\Lambda_b \to \Lambda \gamma) = (6.8 \pm 3.3 ) \times 10^{-6}$, which agrees to the experimental value of $(7.1\pm 1.7)\times 10^{-6}$.Comment: 21 pages, 2 figure

Nonleptonic decays of Ξcc→Ξcπ\Xi_{cc}\to \Xi_c \pi with Ξc−Ξc′\Xi_c-\Xi_c' mixing

Aiming on testing the $\Xi_c-\Xi_c'$ mixing, we study the decays of $\Xi_{cc}\to \Xi_c \pi$ with $\Xi_{cc} = (\Xi_{cc}^{++} , \Xi_{cc} ^+ )$, $\Xi_c = (\Xi_c^{(\prime)+},\Xi_c^{(\prime)0})$ and $\pi = (\pi^+ , \pi^0)$. The soft-meson limit is considered along with the pole model, and the baryon matrix elements are evaluated by the bag model with and without removing the center-of-mass motion (CMM). We find that the four-quark operator matrix elements are about twice larger once the unwanted CMM is removed. We obtain that ${\cal R} = {\cal B}(\Xi_{cc}^+ \to \Xi_c^{\prime +} \pi^+ )/ {\cal B}(\Xi_{cc}^+ \to \Xi_c^{ +} \pi^+ ) = 0.87^{+0.17}_{-0.11}$ and $1.45$ with and without removing the CMM, where the former is close to the lower bound and the later is well consistent with ${\cal R} = 1.41 \pm 0.17 \pm 0.10$ measured at LHCb. In addition, we show that after including the mixing, the up-down asymmetry of $\alpha( \Xi_{cc}^+ \to \Xi_c^{(\prime)0 } \pi^+)$ flips sign. Explicitly, we obtain that $\alpha(\Xi_{cc}^{+} \to \Xi_c^{\prime +} \pi^0) = 0.52$ and $\alpha(\Xi_{cc}^{+} \to \Xi_c^{ 0 } \pi^+) = 0.31$ with and without the CMM corrections, respectively, which are all negative if the mixing is absence. As a bonus, a positive value of $\alpha(\Xi_{cc}^{+} \to \Xi_c^{\prime 0} \pi^+)$ in experiments can also serve as the evidence of the $W$-exchange contributions.Comment: 17 pages, 1 figure, accepted by Physical Review

Hidden Trends in 90 Years of Harvard Business Review

In this paper, we demonstrate and discuss results of our mining the abstracts of the publications in Harvard Business Review between 1922 and 2012. Techniques for computing n-grams, collocations, basic sentiment analysis, and named-entity recognition were employed to uncover trends hidden in the abstracts. We present findings about international relationships, sentiment in HBR's abstracts, important international companies, influential technological inventions, renown researchers in management theories, US presidents via chronological analyses.Comment: 6 pages, 14 figures, Proceedings of 2012 International Conference on Technologies and Applications of Artificial Intelligenc

Isospin violating decays of vector charmonia

We study the isospin violating decays of vector charmonia to $\Lambda\overline{\Sigma}^0$ and $\rho^{0}\omega^{0}$. They are dominated by the single photon annihilation and can be evaluated reliably with timelike form factors. We utilize the quark-pair creation model, which is valid for the OZI suppressed decays, to evaluate the form factors. We obtain the branching fractions of ${\cal B}(J/\psi\to\Lambda\overline{\Sigma}^0+c.c.)=(2.4\pm0.4)\times10^{-5}$ and ${\cal B}(\psi(2S)\to\Lambda\overline{\Sigma}^0+c.c.)=(3.0\pm0.5)\times10^{-6}$, which are compatible with the measurements by the BESIII collaborations, respectively. The decay asymmetries are found to be $\alpha_{J/\psi}=0.314$ and $\alpha_{\psi(2S)}=0.461$. We predict the branching fractions for mesonic final states as ${\cal B}(J/\psi\to\rho^0\omega^0)=(4.04\pm0.31)\times10^{-3}$ and ${\cal B}(\psi(2S)\to\rho^0\omega^0)=(5.1\pm0.4)\times10^{-4}$, and the corresponding decay asymmetries as $\alpha_{J/\psi}=0.148$ and $\alpha_{\psi(2S)}=0.313$, which can be examined at BESIII in the foreseeable future.Comment: 14 pages, 3 figure

New Signature of low mass Z′Z^\prime in J/ψJ/\psi decays

We explore a new approach to search for a low-mass $Z^{\prime}$ particle through $J/\psi$ decays by identifying its existence through parity-violating phenomena in the isospin-violating final states of $\Lambda\overline{\Sigma}^{0}$ and the corresponding charge conjugated states of $\overline{\Lambda}\Sigma^{0}$. Our investigation centers on a generation-independent and leptophobic $Z^{\prime}$ with its mass below 10 GeV. Given the present experimental conditions at the Beijing Spectrometer III~(BESIII) and the anticipated opportunities at the Super Tau Charm Factory~(STCF), we conduct Monte-Carlo simulations to predict possible events at both facilities. Our simulations indicate that BESIII experiments hold the potential to detect $Z^{\prime}$ signals in $J/\psi\to\Lambda\overline{\Sigma}^{0}$ if the polarization asymmetry paramter $\alpha_{\text{NP}}$ attains a minimum threshold of 0.02. Notably, we foresee a substantial enhancement in the precision of the lower limit estimation of $\alpha_{\text{NP}}$ as well as a reduction in statistical uncertainty with upcoming STCF experiments. Furthermore, it is essential to highlight that a null result in the measurement of $\alpha_{\text{NP}}$ would impose stringent constraints, requiring the $Z^{\prime}$ coupling to be on the order of $10^{-2}$.Comment: 9 pages, 3 figure

Anatomy of Λc+\Lambda_c^+ semileptonic decays

We present a systematic study of $\Lambda_c^+ \to {\cal B}_q \ell^+ \nu_\ell$ with ${\cal B}_q = (\Lambda, n)$ and $\ell =( e, \mu)$, examining all the possible decay observables based on the homogeneous bag model (HBM) and lattice QCD (LQCD). With the HBM, we find that the branching fractions and polarization asymmetries of the daughter baryon $\Lambda$ are ${\cal B}(\Lambda_c^+ \to \Lambda e^+ \nu_e, \Lambda \mu^+ \nu_\mu, n \ell ^+ \nu_\ell ) = (3.78 \pm 0.25, 3.67\pm 0.23, 0.40\pm 0.04 )\%$ and $\alpha_\Lambda (\Lambda_c^+ \to \Lambda e^+ \nu_e,\Lambda\mu^+ \nu_\mu ) =(-82.6,-82.3)\%$, respectively. From the LQCD, we obtain that $\alpha_{\Lambda}(\Lambda_c^+ \to \Lambda e^+ \nu_e, \mu^+ \nu_\mu ) = (-87.4\pm 1.0,-87.2\pm 1.0)\%$. We also explore the time-reversal asymmetries due to new physics beyond the standard model. All our results are consistent with the current experimental data, while some of them are accessible to the experiments at BESIII and Belle II.Comment: 22 pages, 13 figure