Lambda_c baryon

Lambda_c baryon
Name	Lambda_c^+
Type	Baryon
Composition	c u d
Quark content	charm up down
Charge	+1 e
Spin	1/2
Mass	2286.46 MeV/c^2
Lifetime	2.00×10^-13 s
Discoverer	MARK II, CLEO, ARGUS
Year	1975–1990s

Lambda_c baryon is the lightest charmed baryon composed of one charm quark and two light quarks. It plays a central role in studies at facilities such as SLAC National Accelerator Laboratory, CERN, Fermilab, KEK and collaborations including CLEO, Belle, BaBar, LHCb and ALICE. Measurements of its mass, lifetime, and decay channels have informed models from Quantum Chromodynamics to heavy-quark effective theories used at institutions like Brookhaven National Laboratory and DESY.

Overview

The Lambda_c^+ is a ground-state spin-1/2 baryon in the charmed sector discovered amid searches by experiments like MARK II and later studied by ARGUS and CLEO. Its existence connected observations at SLAC with discoveries at CERN and KEK, linking experimental programs run by collaborations including Belle II and BaBar. As a member of the lowest-lying charmed baryon multiplet it is analogous to baryons observed in experiments at Fermilab and theoretical analyses at MIT and Caltech.

Properties

Intrinsic properties measured for Lambda_c include mass, charge, spin, parity, isospin and magnetic moments. Precision determinations by teams at LHCb, CLEO-c, Belle, BaBar and CDF complement lattice QCD computations from groups at Riken, Brookhaven National Laboratory, Yale University, University of Edinburgh and MIT. The baryon’s quark content (cud) relates it to charm spectroscopy studied by researchers at IHEP, JINR and TRIUMF, and comparisons are drawn to strange baryons cataloged at CERN and SLAC.

Production and Detection

Production channels include e^+e^- annihilation at colliders like KEKB, hadroproduction at LHC, Tevatron experiments such as CDF and fixed-target programs at CERN SPS. Detection strategies used by LHCb, ALICE, CMS and ATLAS exploit vertexing with detectors developed by teams at CERN, INFN, Brookhaven National Laboratory and DESY. Triggering and reconstruction techniques trace lineages to instrumentation from SLAC, Fermilab, TRIUMF and KEK, while software frameworks from CERN and collaborations like ROOT are widely used. Experiments including Belle II and BaBar compare inclusive and exclusive production studied at CLEO and ARGUS.

Decay Modes and Lifetimes

Lambda_c decays weakly into final states such as p K^- π^+, Λ π^+ and semileptonic channels investigated by CLEO, BaBar, Belle, LHCb and ALICE. Branching fraction measurements by PDG compilations rely on results from CLEO-c, BESIII, Belle, BaBar and LHCb. Lifetime determinations from SELEX and WA89 are compared with precision results at LHCb and CDF, and theoretical inputs come from groups at TU Munich, University of Barcelona, University of Tokyo and Zhejiang University.

Theoretical Significance and Structure

The Lambda_c provides a testing ground for frameworks like Heavy Quark Effective Theory developed at CERN, University of Chicago, Harvard University and Princeton University. Its internal dynamics are modeled via lattice QCD by collaborations at Riken, Fermilab Lattice and MILC and EPFL, and by quark model approaches from researchers at MIT, Caltech, George Washington University and Institute for Nuclear Theory. Studies of form factors, SU(4) symmetry breaking, and nonleptonic amplitudes link work at Max Planck Institute, Institute for High Energy Physics (IHEP), JLab and Stony Brook University.

Experimental Results and Measurements

Key experimental milestones include mass and lifetime precision updates from LHCb, branching fraction catalogs by PDG, semileptonic form-factor studies at BESIII and Belle II, and excited-state spectroscopy from CMS, ATLAS and LHCb. Searches for rare or CP-violating decays have been reported by BaBar, Belle, CLEO, BESIII and LHCb with theoretical interpretation from groups at CERN, IHEP, SLAC and DESY. Upcoming measurements are planned at Belle II, high-luminosity LHC runs coordinated by CERN and at upgraded facilities at KEK and J-PARC.

Category:Charmed baryons