Baryon
[8] However, in July 2015, the LHCb experiment observed two resonances consistent with pentaquark states in the Λ0b → J/ψK−p decay, with a combined statistical significance of 15σ.This might include neutrinos and free electrons, dark matter, supersymmetric particles, axions, and black holes.[11] Within the prevailing Standard Model of particle physics, the number of baryons may change in multiples of three due to the action of sphalerons, although this is rare and has not been observed under experiment.Some grand unified theories of particle physics also predict that a single proton can decay, changing the baryon number by one; however, this has not yet been observed under experiment.The concept of isospin was first proposed by Werner Heisenberg in 1932 to explain the similarities between protons and neutrons under the strong interaction.For example, the four Deltas all have different charges (Δ++ (uuu), Δ+ (uud), Δ0 (udd), Δ− (ddd)), but have similar masses (~1,232 MeV/c2) as they are each made of a combination of three u or d quarks.Isospin, although conveying an inaccurate picture of things, is still used to classify baryons, leading to unnatural and often confusing nomenclature.Particles could be described with isospin projections (related to charge) and strangeness (mass) (see the uds octet and decuplet figures on the right).As other quarks were discovered, new quantum numbers were made to have similar description of udc and udb octets and decuplets.They are related to the number of strange, charm, bottom, and top quarks and antiquark according to the relations: meaning that the Gell-Mann–Nishijima formula is equivalent to the expression of charge in terms of quark content: Spin (quantum number S) is a vector quantity that represents the "intrinsic" angular momentum of a particle.Particle physicists are most interested in baryons with no orbital angular momentum (L = 0), as they correspond to ground states—states of minimal energy.Gravity, the electromagnetic force, and the strong interaction all behave in the same way regardless of whether or not the universe is reflected in a mirror, and thus are said to conserve parity (P-symmetry).It turns out that this is not quite true: for the equations to be satisfied, the wavefunctions of certain types of particles have to be multiplied by −1, in addition to being mirror-reversed.There are six groups of baryons: nucleon (N), Delta (Δ), Lambda (Λ), Sigma (Σ), Xi (Ξ), and Omega (Ω).
BariumBaryonyxStandard Modelparticle physicsElementary particlesQuantum field theoryGauge theorySpontaneous symmetry breakingHiggs mechanismElectroweak interactionQuantum chromodynamicsCKM matrixStandard Model mathematicsStrong CP problemHierarchy problemNeutrino oscillationsPhysics beyond the Standard ModelRutherfordThomsonChadwickSudarshanDavis JrAndersonFeynmanRubbiaGell-MannKendallTaylorFriedmanPowellGlashowIliopoulosLedermanMaianiChamberlainCabibboSchwartzMajoranaWeinbergKobayashiMaskawaYukawa't HooftVeltmanPolitzerReinesSchwingerWilczekCroninEnglertGuralnikKibblede MayoloLattescompositesubatomic particlevalence quarksProtonsneutronsquarkshadronfamily of particlesfermionsAbraham Paisantiparticleprotonup quarksdown quarkantiprotonresidual strong forcemediatedmesonsmatteruniversenucleuselectronsleptonsExotic baryonspentaquarkswarm–hot intergalactic mediumstrong nuclear forceFermi–Dirac statisticsPauli exclusion principlebosonshadronsbaryon numbersstatistical significanceneutrinosdark mattersupersymmetric particlesaxionsblack holesantiparticlesbaryogenesisbaryon numbersphaleronsgrand unified theoriesconservation of baryon numberIsospinuds baryon decupletuds baryon octetWerner Heisenbergstrong interactionEugene WignerMurray Gell-Mannquark modelDeltascharged stateDelta particlePauli's exclusion principlestrangenessbrokenGell-Mann–Nishijima formulabottomnesstopnessSpin (physics)Angular momentum operatorQuantum numbersClebsch–Gordan coefficientsvectorangular momentumnatural unitsfermionicorbital angular momentumazimuthal quantum numbertotal angular momentum