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arXiv · 1411.3402

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

Jonathan M. M. Hall·Waseem Kamleh·Derek B. Leinweber·Benjamin J. Menadue·Benjamin J. Owen·Anthony W. Thomas·Ross D. Young
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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.

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Jonathan M. M. Hall, Waseem Kamleh, Derek B. Leinweber, Benjamin J. Menadue, Benjamin J. Owen, Anthony W. Thomas, Ross D. Young. 2015-04-14. Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule. https://doi.org/10.1103/physrevlett.114.132002

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