Families of Particles

Some particles share characteristics. Because of this, the physicists classify them into families. The quark model is fundamental to perform this classification.

Table 1: The Most important physical properties of the quarks.

	Property            quark	d	u	s	c	b	t
	q, electric charge	-$\frac{1}{3}$	+$\frac{2}{3}$	-$\frac{1}{3}$	+$\frac{2}{3}$	-$\frac{1}{3}$	+$\frac{2}{3}$
	$I_z$, isospin, z comp.	-$\frac{1}{2}$	+$\frac{1}{2}$	0	0	0	0
	s, strangeness	0	0	-1	0	0	0
	c, charm	0	0	0	+1	0	0
	b, bottom	0	0	0	0	-1	0
	t, top	0	0	0	0	0	+1

Table 2: Quark physical properties.

	Quarks
	Flavor		Mass$(GeV/c^2$)	Electric charge (e)
	u	up	0.004	$+\frac{2}{3}$
	d	down	0.008	$-\frac{1}{3}$
	c	charm	1.5	$+\frac{2}{3}$
	s	strange	0.15	$-\frac{1}{3}$
	t	top	176	$+\frac{2}{3}$
	b	bottom	4.7	$-\frac{1}{3}$

The actual classification is not complete. It is still changing. Because we do not know all the particles, and their properties. For example, we do not know yet in a definitive form the mass of the neutrinos.

Table 1 and 2 illustrate the properties of the quarks.

The Table 3 and 4 illustrate two families of mesons. Each one has 16 particles.

The Table 5 and 6 illustrates two families of baryons. Each one has 20 particles.

Table 3: Family, multiplet, of mesons. Family of 16 particles, pseudoscalar mesons.

			$D^+_s(c \bar s)$
	$D^0(c \bar u)$				$D^+(c \bar d)$
		$K^0(d\bar s)$		$K^+(u\bar s)$
$\pi^-(d \bar u)$			$\pi^0$,$\eta$,$\eta_c$,$\eta'$			$\pi^+(u \bar d)$
	$K^-(s \bar u)$				$\bar K^0(s \bar d)$
		$D^-(d \bar c)$		$\bar{D^0}(u \bar c)$
			$D^-_s(s \bar c)$

Table 4: Family of 16 particles. Vectorial mesons.

			$D^{*+}_s(c \bar s)$
	$D^{*0}(c \bar u)$				$D^{*+}(c \bar d)$
		$K^{*0}(d\bar s)$		$K^{*+}(u\bar s)$
$\rho^-(d \bar u)$			$\rho^0$,$\omega$,$J/\Psi$,$\phi$			$\rho^+(u \bar d)$
	$K^{*-}(s \bar u)$				$\bar K^{*0}(s \bar d)$
		$D^{*-}(d \bar c)$		$\bar D^{*0}(u \bar c)$
			$D^{*-}_s(s \bar c)$

In both cases, note the arrangements in the electric charge and in the constitution of quarks.

The student can put the masses, or another physical parameter like the isospin, to the particles and observe the distribution, in the masses or in the physical parameter, in each of the arrangements. Also he or she can take the differences in the masses, of pairs of particles that are on the same vertical u horizontal line.

The student must conclude by herself or by himself, after thinking on the above schemes. Maybe he or she can create another way of classifying the particles.