Study of the anomalous cross-section lineshape of e^+e^-\to D\bar D at \psi(3770) with an effective field theory

We study the anomalous cross-section lineshape of $e^+e^-\rightarrow D\bar D$ with an effective field theory. Near the threshold, most of the $D\bar D$ pairs are from the decay of $\psi(3770)$. Taking into account the fact that the nonresonance background is dominated by the $\psi(2S)$ transition, the produced $D\bar D$ pair can undergo final-state interactions before the pair is detected. We propose an effective field theory for the low-energy $D\bar D$ interactions to describe these final-state interactions and find that the anomalous lineshape of the $D\bar D$ cross section observed by the BESII collaboration can be well described.Comment: 10 pages,6 figures, redo the calculation with PDS scheme and more discussions added, accepted by Phys.Lett.

The nature of ZbZ_b states from a combined analysis of Υ(5S)→hb(mP)π+π−\Upsilon(5S)\rightarrow h_b(mP) \pi^+ \pi^- and Υ(5S)→B(∗)Bˉ(∗)π\Upsilon(5S)\rightarrow B^{(\ast)}\bar B^{(\ast)}\pi

With a combined analysis of data on $\Upsilon(5S)\rightarrow h_b(1P,2P)\pi^+\pi^-$ and $\Upsilon(5S)\rightarrow B^{(\ast)}\bar B^{(\ast)}\pi$ in an effective field theory approach, we determine resonance parameters of $Z_b$ states in two scenarios. In one scenario we assume that $Z_b$ states are pure molecular states, while in the other one we assume that $Z_b$ states contain compact components. We find that the present data favor that there should be some compact components inside $Z_b^{(\prime)}$ associated with the molecular components. By fitting the invariant mass spectra of $\Upsilon(5S)\rightarrow h_b(1P,2P)\pi^+\pi^-$ and $\Upsilon(5S)\rightarrow B^{(\ast)}\bar B^{\ast}\pi$, we determine that the probability of finding the compact components in $Z_b$ states may be as large as about $40\%$.Comment: Discussions added, version published in EPJ

Discrete mechanics Based on Finite Element Methods

Discrete Mechanics based on finite element methods is presented in this paper. We also explore the relationship between this discrete mechanics and Veselov discrete mechanics. High order discretizations are constructed in terms of high order interpolations.Comment: 14 pages, 0 figure

Constraints on anomalous quartic gauge couplings via WγjjW\gamma jj production at the LHC

The vector boson scattering at the Large Hadron Collider (LHC) is sensitive to anomalous quartic gauge couplings (aQGCs). In this paper, we investigate the aQGC contribution to $W \gamma jj$ production at the LHC with $\sqrt{s}=13$ TeV in the context of an effective field theory (EFT). The unitarity bound is applied as a cut on the energy scale of this production process, which is found to have significant suppressive effects on the signals. To enhance the statistical significance, we analyse the kinematic and polarization features of the aQGC signals in detail. We find that the polarization effects induced by the aQGCs are unique and can discriminate the signals from the SM backgrounds well. With the proposed event selection strategy, we obtain the constraints on the coefficients of dimension-8 operators with current luminosity. The results indicate that the process $pp \to W \gamma jj$ is powerful for searching for the $O_{M_{2,3,4,5}}$ and $O_{T_{5,6,7}}$ operators.Comment: 29 pages, 11 figures, 7 tables, to be published in Chinese Physics