Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule

Abstract

For almost 50 years the structure of the Lambda(1405) resonance has been a mystery. Even though it contains a heavy strange quark and has odd parity, its mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers speculated that it might be a molecular state of an antikaon bound to a nucleon. However, a standard quark-model structure is also admissible. Although the intervening years have seen considerable effort, there has been no convincing resolution. Here we present a new lattice QCD simulation showing that the strange magnetic form factor of the Lambda(1405) vanishes, signaling the formation of an antikaon-nucleon molecule. Together with a Hamiltonian effective-field-theory model analysis of the lattice QCD energy levels, this strongly suggests that the structure is dominated by a bound antikaon-nucleon component. This result clarifies that not all states occurring in nature can be described within a simple quark model framework and points to the existence of exotic molecular meson-nucleon bound states.

Manuscript accepted for publication. 4 figures, 5 pages

References in corpus (3)

• Scalar mesons moving in a finite volume and the role of partial wave mixing
• New insights into antikaon-nucleon scattering and the structure of the Lambda(1405)
• The nature of Lambda(1405) hyperon resonance in chiral dynamics

Cited by in corpus (41)

• Baryons as relativistic three-quark bound states
• Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules
• Three-body Unitarity in the Finite Volume
• The ALICE experiment: a journey through QCD
• On the History of Dibaryons and their Final Observation
• Structure of the $\mathbf{\Lambda }(1405)$ from Hamiltonian effective field theory
• Hamiltonian effective field theory study of the ${\mathbf{N}}^{\ast }(1440)$ resonance in lattice QCD
• Deuteron-like states composed of two doubly charmed baryons
• Constraining the $\overline{\mathrm{K}}\mathrm{N}$ coupled channel dynamics using femtoscopic correlations at the LHC
• Cross-channel constraints on resonant antikaon-nucleon scattering
• Generalized weak-binding relations of compositeness in effective field theory
• Two-pole nature of the $\Lambda (1405)$ from lattice QCD
• Lattice QCD study of $\pi \Sigma -\bar{K}N$ scattering and the $\Lambda (1405)$ resonance
• Determination of the real part of the η'-Nb optical potential
• Review of the low-lying excited baryons ${\Sigma }^{\ast }(1/2^{-})$
• Analysis of the ${\eta }_1(1855)$ as a $K{\bar{K}}_1(1400)$ molecular state
• New insights into the nature of the $\Lambda (1380)$ and $\Lambda (1405)$ resonances away from the SU(3) limit
• First Observation of $\Lambda {\pi }^{+}$ and $\Lambda {\pi }^{-}$ Signals near the $\bar{K}N(I=1)$ Mass Threshold in ${\Lambda }_c^{+}\to \Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}$ Decay
• Flavor structure of $\Lambda$ baryons from lattice QCD: From strange to charm quarks
• ${\Lambda }_c$ Semileptonic Decays in a Quark Model
• New insights into the pole parameters of the $\Lambda (1380)$, the $\Lambda (1405)$ and the $\Sigma (1385)$
• The investigations of the $P$-wave $B_s$ states combining quark model and lattice QCD in the coupled channel framework
• Constraining beyond the Standard Model nucleon isovector charges
• Observation of $\Omega (2012{)}^{-}\to \Xi (1530)\bar{K}$ and measurement of the effective couplings of $\Omega (2012{)}^{-}$ to $\Xi (1530)\bar{K}$ and $\Xi \bar{K}$
• Structure of the $\mathbf{\Lambda }(1670)$ resonance
• MESON2016 -- Concluding Remarks
• Pole trajectories of the $\Lambda (1405)$ helps establish its dynamical nature
• Pion photoproduction of nucleon excited states with Hamiltonian effective field theory
• Studying the bound state of the $K^{-}p$ system in the Bethe-Salpeter formalism
• Inverse scattering problem with a bare state
• Structure of the ${\Omega }^{-}(2012)$ with Hamiltonian Effective Field Theory
• QCD sum rule study for hidden-strange pentaquarks
• Reflections on Chiral Symmetry within QCD
• $\Delta$ baryon spectroscopy in lattice QCD
• The odd-parity strange baryons $\Sigma ({\frac{1}{2}}^{-})$ below 1.8 GeV with Hamiltonian effective field theory
• A possible interpretation of $\Lambda$ baryon spectrum with pentaquark components
• Exotic properties of N^*(1895) and its impact on photoproduction of light hyperons
• Chirally motivated $\pi \Sigma$-$\bar{K}N$ model in a finite volume
• Odd-Parity Nucleon Electromagnetic Transitions in Lattice QCD
• On the Structure of the Lambda 1405
• Electromagnetic transition form factors and Dalitz decays of hyperons