We study a model of scalars which includes both the SM Higgs and scalar singlet as composites heavy vector-like fermions. The fermions are bounded by super-strong four-fermion interactions. decays to vector bosons through loop show that surprisingly large production cross section di-photon events at 750 GeV resonance odd decay properties can all be explained. This serves good for GeV.

We study the property of $X(3872)$ meson by analyzing $B\to K D\bar D^*$ and J/\psi \pi^+\pi^-$ decay processes. The competition between rescattering mediated through a Breit-Wigner resonance generated from local $D\bar{D}^* \to D\bar{D}^*$ interaction is carefully studied an effective lagrangian approach. Three different fits are performed: pure case, $D\bar{D}^*$ molecule case with only vertices (generated loop chain), mixed case. It found that data supports picture where X(3872) mainly...

The analysis of the LHCb data on found in di- system was performed using a momentum-dependent Flatté-like parameterization. use pole counting rule and spectral density function sum provides consistent evidence that both confining molecular states are possible. Alternatively, nature cannot be distinguished if only experimental with current statistics available. Nevertheless, we lowest state likely has same quantum numbers as , is probably not interpreted state.

A comprehensive study on the nature of ${Z}_{c}(3900)$ resonant structure is carried out in this work. By constructing pertinent effective Lagrangians and considering important final-state-interaction effects, we first give a unified description to all relevant experimental data available, including $J/\ensuremath{\psi}\ensuremath{\pi}$ $\ensuremath{\pi}\ensuremath{\pi}$ invariant mass distributions from...

A careful reanalysis is made on ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}X(4660)\ensuremath{\rightarrow}({\mathrm{\ensuremath{\Lambda}}}_{c}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c})/({\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\pi}\ensuremath{\pi})$ processes, aiming at resolving the apparent conflicts between Belle and BESIII data above ${\mathrm{\ensuremath{\Lambda}}}_{c}{\overline{\mathrm{\ensuremath{\Lambda}}}}_{c}$ threshold. We use a model containing Breit-Wigner...

Abstract A near-threshold enhancement in the $$D^{+}_{s}D^{-}_{s}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>D</mml:mi><mml:mi>s</mml:mi><mml:mo>+</mml:mo></mml:msubsup><mml:msubsup><mml:mi>D</mml:mi><mml:mi>s</mml:mi><mml:mo>-</mml:mo></mml:msubsup></mml:mrow></mml:math> system, dubbed as X (3960), is observed by LHCb collaboration recently. combined analysis on $$\chi _{c0}(3930)~(\rightarrow D^+ D^-)$$...

We analyze ππ-K and πη-K couple channel [1,1] matrix Padé amplitudes of SU(3) × chiral perturbation theory. By fitting phase shift inelasticity data, we determine pole positions in different channels (f0(980), a0(980), f0(600), K*0(800), K*(892), ρ(770)) trace their Nc trajectories. stress that a Breit—Wigner resonance should exhibit two poles on Riemann sheets meet each other the real axis when = ∞. Poles are hence classified using this criteria conclude K* (892) ρ(770) unambiguous...

We perform a thorough analysis of the $VP\ensuremath{\gamma}({\ensuremath{\gamma}}^{*})$ and $P\ensuremath{\gamma}\ensuremath{\gamma}({\ensuremath{\gamma}}^{*})$ decays in resonance chiral theory, where $V$ stands for vector resonances $\ensuremath{\rho}$, ${K}^{*}$, $\ensuremath{\omega}$, $\ensuremath{\phi}$; $P$ $\ensuremath{\pi}$, $K$, $\ensuremath{\eta}$, ${\ensuremath{\eta}}^{\ensuremath{'}}$; ${\ensuremath{\gamma}}^{*}$ subsequently into lepton pairs. Upon imposing QCD short-distance...

Neural networks are trained to judge whether or not an exotic state is a hadronic molecule of given channel according its line-shapes. This method performs well in both trainings and validation tests. As applications, it applied study $X(3872)$, $X(4260)$ $Z_c(3900)$. The results show that $Z_c(3900)$ should be regarded as $\bar{D}^* D$ molecular but $X(3872)$ not. for $X(4260)$, can $\chi_{c0}\omega$. Some discussions on $X_1(2900)$ also provided.

We compare contributions from the triangle diagram and $$D\bar{D}^*$$ bubble chain with processes of $$e^{+}e^{-}\rightarrow J/\psi \pi ^{+}\pi ^{-}$$ (D\bar{D}^*)^\mp ^{\pm }$$ . By fitting $$J/\psi $$ maximum spectrum spectrum, we find that cannot explain new experimental results BESIII Collaboration at center mass 4.23 4.26 GeV, simultaneously. On contrary, molecular assignment $$Z_c(3900)$$ gives a much better description.

The analyses of the LHCb data on X(2900) in D^- K^+ spectrum are performed. Both dynamically generated and explicitly introduced X_1(2900) considered. results show that both these two approaches support interpretation as a bar{D}_1 K molecular state, with J^{P}=1^- an iso-singlet is much more favorable. effect triangle singularity production also discussed, it found cannot be interpreted pure cusp.

The analyses of the LHCb data on $X(6900)$ found in di-$J/\psi$ and $J/\psi \psi(3686)$ systems are performed using a momentum-dependent {Flatt\'{e}}-like parameterization. use pole counting rule spectral density function sum give consistent conclusions that may not be molecule \psi(3686)$. Nevertheless it is still possible higher states, such as $J/\psi\psi(3770)$, $\chi_{c0}\chi_{c2}$, etc.

Within the framework of chiral effective field theory, we study various electromagnetic processes with light vector resonances: ${K}^{*}(892)\ensuremath{\rightarrow}K\ensuremath{\gamma}$, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{*}(892)K$, and $\ensuremath{\omega}\ensuremath{\pi}{\ensuremath{\gamma}}^{*}$ form factors. With two multiplets resonances being introduced, fit decay widths ${K}^{*0}\ensuremath{\rightarrow}{K}^{0}\ensuremath{\gamma}$,...

The S- and P- wave phase shifts of low-energy pion-nucleon scatterings are analysed using Peking University representation, in which they decomposed into various terms contributing either from poles or branch cuts. We estimate the left-hand cut contributions with help tree-level perturbative amplitudes derived relativistic baryon chiral perturbation theory up to $$\mathcal {O}(p^2)$$ . It is found that $$S_{11}$$ $$P_{11}$$ channels, known resonances cuts far enough saturate experimental...

In a previous paper (Commun. Theor. Phys. 57 (2012) 841), we proposed method to distinguish poles of different dynamical origin, in unitarized amplitude $\pi\pi\, K\bar K$ system. That is based on the observation that `A Breit-Wigner resonance should exhibit two Riemann sheets which meet each other real axis when $N_c=\infty$'. this paper, extend our work (Commun.Theor.Phys. 841) $\pi\pi$-$K\bar K$-$\eta\eta$ three channel We reconfirm most predictions. Especially $f_0(980)$ $K\bar molecule...

Roy-equation analysis on lattice data of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>π</a:mi><a:mi>π</a:mi></a:math> scattering phase shifts at <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msub><c:mi>m</c:mi><c:mi>π</c:mi></c:msub><c:mo>=</c:mo><c:mn>391</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:mi>MeV</c:mi></c:math> reveals that the lowest <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"...

Abstract New measurements on cross sections in $$e^+e^-\rightarrow J/\psi \pi ^+\pi ^-$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>e</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>-</mml:mo> <mml:mo>→</mml:mo> <mml:mi>J</mml:mi> <mml:mo>/</mml:mo> <mml:mi>ψ</mml:mi> <mml:mi>π</mml:mi> </mml:mrow> </mml:math> , $$h_c\pi <mml:msub> <mml:mi>h</mml:mi> <mml:mi>c</mml:mi> </mml:msub> $$D^0D^{*-}\pi ^++c.c.$$ <mml:mi>D</mml:mi> <mml:mn>0</mml:mn>...

Systematic and careful studies are made on the properties of IJ = 00 ππ K coupled–channel system, using newly derived dispersion relations between phase shifts poles cuts. The effects nearby branch point singularities to determination f0(980) resonance estimated discussed.