Electromagnetic form factors of $\Lambda$ hyperon in the vector meson dominance model and a possible explanation of the near-threshold enhancement of the $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ reaction

Abstract

The near-threshold $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ reaction is studied with the assumption that the production mechanism is due to a near-$\Lambda \bar{\Lambda }$-threshold bound state. The cross section of $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ reaction is parametrized in terms of the electromagnetic form factors of $\Lambda$ hyperon, which are obtained with the vector meson dominance model. It is shown that the contribution to the $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ reaction from a new narrow state with quantum numbers $J^{PC}=1^{--}$ is dominant for energies very close to threshold. The mass of this new state is around 2231 MeV, which is very close to the mass threshold of $\Lambda \bar{\Lambda }$, while its width is just a few MeV. This gives a possible solution to the problem that all previous calculations seriously underestimate the near-threshold total cross section of the $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ reaction. We also note that the near-threshold enhancement can be also reproduced by including these well established vector resonances $\omega (1420)$, $\omega (1650)$, $\varphi (1680)$, or $\varphi (2170)$ with a Flatt$\acute{\mathrm{e}}$ form for their total decay width, and a strong coupling to the $\Lambda \bar{\Lambda }$ channel.

arXiv commentPublished version

References in corpus (52)

• Measurement of GEp/GMp in ep -> ep to Q2 = 5.6 GeV2
• Strong Decays of Strange Quarkonia
• Hybrid Meson Decay Phenomenology
• Study of e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 using Initial State Radiation with BABAR
• X(2175) as a resonant state of the $\varphi K\bar{K}$ system
• Analysis of Y(2175) as a tetraquark state with QCD sum rules
• Re-analysis of the nucleon space- and time-like electromagnetic form factors in a two-component model
• Hadronic structure functions in the $e^{+}{e}^{-}\to \bar{\Lambda }\Lambda$ reaction
• A Candidate for $1^{--}$ Strangeonium Hybrid
• Y(2175): Distinguish Hybrid State from Higher Quarkonium
• Observation of a cross-section enhancement near mass threshold in $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$
• Possible Deuteron-like Molecular States Composed of Heavy Baryons
• Nucleon Electromagnetic Form Factors in the Timelike Region
• Unexpected features of e+e-->ppbar and e+e-->lambda-lambdabar cross sections near threshold
• Measurement of $e^{+}{e}^{-}\to K^{+}{K}^{-}$ cross section at $\sqrt{s}=2.00-3.08$ GeV
• Structure of the nucleon from electromagnetic space-like and time-like form factors
• Covariant L-S Scheme for the effective N*NM couplings
• Periodic interference structures in the time-like proton form factor
• The Y(2175) State in the QCD Sum Rule
• Complete measurement of $\Lambda$ electromagnetic form factors
• The electromagnetic form factors of the $\Lambda$ in the timelike region
• Reconciling the X(4630) with the Y(4660)
• Production of the Exotic $1^{--}$ Hadrons $\varphi (2170)$, X(4260) and $Y_b(10890)$ at the LHC and Tevatron via the Drell-Yan Mechanism
• Selected strong decays of $\eta (2225)$ and $\varphi (2170)$ as $\Lambda \bar{\Lambda }$ bound states
• The meson-exchange model for the $\Lambda \bar{\Lambda }$ interaction
• Polarization observables in the $e^{+}{e}^{-}\to \bar{\Lambda }\Lambda$ reaction
• Observation of a resonant structure in $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0{\pi }^0$
• Observation of a resonant structure in $e^{+}{e}^{-}\to \omega \eta$ and another in $e^{+}{e}^{-}\to \omega {\pi }^0$ at center-of-mass energies between 2.00 and 3.08 GeV
• The electromagnetic form factors of $\Lambda$ hyperon in the vector meson dominance model
• Hyperon electromagnetic form factors in the timelike region
• Observation of a structure in $e^{+}{e}^{-}\to \varphi {\eta }^{\prime }$ at $\sqrt{s}$ from 2.05 to 3.08 GeV
• Mass spectrum and strong decays of strangeonium in a constituent quark model
• Discussions on the Line-shape of $X(4660)$ Resonance
• Cross section measurements of $e^{+}{e}^{-}\to K^{+}{K}^{-}{K}^{+}{K}^{-}$ and $\varphi K^{+}{K}^{-}$ at center-of-mass energies from 2.10 to 3.08 GeV
• Multichannel calculation of excited vector $\varphi$ resonances and the $\varphi (2170)$
• Study on the strong decays of $\varphi (2170)$ and a grand expectation for the future charm-tau factory
• Nature of the vector resonance $Y(2175)$
• Measurement of the Born cross sections for $e^{+}{e}^{-}\to {\eta }^{\prime }{\pi }^{+}{\pi }^{-}$ at center-of-mass energies between $2.00$ and $3.08$ GeV
• A fast simulation package for STCF detector
• A possible explanation of the threshold enhancement in the process $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$
• Vector mesons and electromagnetic form factor of the $\Lambda$ hyperon
• Study of the process $e^{+}{e}^{-}\to \varphi \eta$ at center-of-mass energies between 2.00 and 3.08 GeV
• The $\varphi (2170)$ production in the process $\gamma p\to \eta \varphi p$
• Cross section measurement of $e^{+}{e}^{-}\to K_S^0{K}_L^0$ at $\sqrt{s}=2.00-3.08\mathrm{GeV}$
• Deciphering the light vector meson contribution to the cross sections of $e^{+}{e}^{-}$ annihilations into the open-strange channels through a combined analysis
• Partial decay widths of $\varphi (2170)$ to kaonic resonances
• The $X(2239)$ and $\eta (2225)$ as hidden-strange molecular states from $\Lambda \bar{\Lambda }$ interaction
• Feasibility study of $CP$ Violation in ${\tau }^{-}\to K_S{\pi }^{-}{\nu }_{\tau }$ decays at Super Tau Charm Facility
• Electromagnetic form factors of ${\Sigma }^{+}$ and ${\Sigma }^{-}$ in the vector meson dominance model
• The cross section of the process $e^{+}{e}^{-}\to p\bar{p}$ in the vicinity of charmonium $\psi (3770)$ including three-gluon and $D$-meson loop contributions
• The electromagnetic form factors of ${\Lambda }_c$ hyperon in the vector meson dominance model
• Flavor content of nucleon form factors in a VMD approach

Cited by in corpus (14)

• Toy model to understand oscillatory behavior in timelike nucleon form factors
• The $\Sigma$ and $\Xi$ electromagnetic form factors in the extended vector meson dominance model
• Electromagnetic form factors of neutron and neutral stange hyperons in the oscillating view of point
• Determination of the ${\Sigma }^{+}$ Timelike Electromagnetic Form Factors
• Production and decay of polarized hyperon-antihyperon pairs
• Dispersion-theoretical analysis of the electromagnetic form factors of the $\Lambda$ hyperon
• $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$ cross sections and the ${\Lambda }_c^{+}$ electromagnetic form factors within the extended vector meson dominance model
• Understanding oscillating features of the timelike nucleon electromagnetic form factors within the extending vector meson dominance model
• The cross section of the process $e^{+}{e}^{-}\to \Lambda \bar{\Lambda }$ in the vicinity of charmonium $\psi (3770)$ including three-gluon and $D$-meson loop contributions
• $\Lambda \bar{\Lambda }$ final-state interaction in the reactions $e^{+}{e}^{-}\to \varphi \Lambda \bar{\Lambda }$ and $e^{+}{e}^{-}\to \eta \Lambda \bar{\Lambda }$
• Measurement of Born cross sections of $e^{+}{e}^{-}\to {\Xi }^0{\bar{\Xi }}^0$ and search for charmonium(-like) states at $\sqrt{s}$ = 3.51-4.95 GeV
• The electromagnetic form factors and spin polarization of ${\Lambda }_c^{+}$ in the process $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$
• Measurement of Born cross section of $e^{+}{e}^{-}\to {\Sigma }^0{\bar{\Sigma }}^0$ at $\sqrt{s}=3.50-4.95$ GeV
• Observation of Transverse Polarization and Determination of Psionic Form Factors of the $\Lambda$ Hyperon at $\sqrt{s}=3.773$ GeV