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Observation of excited Λ(b)(0) baryons
R Aaij1, C Abellan Beteta, A Adametz
1Nikhef National Institute for Subatomic Physics, Amsterdam, Netherlands.
Physical Review Letters
|December 11, 2012
Summary
LHCb researchers discovered two new bottom baryons, Λ(b)(*0)(5912) and Λ(b)(*0)(5920), using proton-proton collision data. These findings advance our understanding of excited baryon states in particle physics.
Area of Science:
- High Energy Physics
- Particle Physics
- Hadron Spectroscopy
Background:
- The Standard Model of particle physics describes fundamental particles and forces.
- Baryons are composite particles made of three quarks, with bottom baryons containing a bottom quark.
- Understanding the spectrum of bottom baryons provides insights into the strong nuclear force and quantum chromodynamics.
Purpose of the Study:
- To search for and characterize new excited states of bottom baryons.
- To investigate the properties of bottom baryon resonances beyond the ground state.
- To contribute to the comprehensive mapping of the bottom baryon spectrum.
Main Methods:
- Analysis of proton-proton collision data collected by the LHCb detector.
- Reconstruction of the Λ(b)(0)π(+)π(-) invariant mass spectrum.
- Statistical analysis to identify significant peaks corresponding to new particle states.
Main Results:
- Observation of two narrow states in the Λ(b)(0)π(+)π(-) spectrum.
- Measured masses of the new states: 5911.97±0.12(stat)±0.02(syst)±0.66(Λ(b)(0) mass) MeV/c(2) and 5919.77±0.08(stat)±0.02(syst)±0.66(Λ(b)(0) mass) MeV/c(2).
- Observed with significances of 5.2 and 10.2 standard deviations, respectively.
Conclusions:
- The observed states are interpreted as orbitally excited Λ(b)(0) baryons, denoted as Λ(b)(*0)(5912) and Λ(b)(*0)(5920).
- These discoveries enrich the known spectrum of bottom baryons.
- The findings provide crucial data for refining theoretical models of hadron structure and spectroscopy.
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