Baryons

 

Baryons are strongly interacting particles having half-integral spins (1/2, 3/2, 5/2 . . . . .). A partial listing of some baryons is given in Table. The familiar members of the baryon family are the proton and neutron. Baryons have distinct antiparticles for example, the antiproton (p) and antineutron (n).

Some selected mesons

Particle	Antiparticle	Charge	Spin (h/2π)	Strangeness	Rest Energy (MeV)	Mean Life (s)	Typical Decay Products
p		+1	½	0	938	ꝏ
n		0	½	0	940	887	p + e- + e
A0		0	½	-1	1116	2.6 x10-10	p + π-
Σ+		+1	½	-1	1189	0.8x10-10	p + π0
Σ0		0	½	-1	1193	7.4x10-20	A0 + ϒ
Σ -		-1	½	-1	1197	1.5x10-10	n + π-
Ξ0		0	½	-2	1315	2.9x10-10	A0 + π0
Ξ-		-1	½	-2	1321	1.6x10-10	A0 + π-
∆*		+2,+1 0,-1	3/2	0	1232	5.9x10-24	p + π
Σ*		+1,0,-1	3/2	-1	1385	1.8x10-23	A0 + π
Ξ*	---	-1, 0	3/2	-2	1530	7.3x10-23	Ξ + π
Ω-	---	-1	3/2	-3	1672	8.2x10-11	A0 +K-
Ae+	---	+1	½	0	2285	2.1x10-13	p +K- + π+
Ab0	---	0	½	0	5624	1.2x10-12	p +D0 + π-

We can produce heavier baryons in reactions between nucleons, such as 

p + p——> p +A^o  + K⁺,

which produces the A^o baryon and the K⁺ meson. The A^o decays according to

A^o ——> p + π^-          (mean life = 2.6 X 107" s).

Although there are no neutrinos produced in the decay, the

mean life indicates that the decay is governed by the weak

interaction.