Answer:
Quarks and antiquarks come in six different flavors: up (
�
u), down (
�
d), charm (
�
c), strange (
�
s), top (
�
t), and bottom (
�
b). Each flavor of quark has a specific electric charge:
Up quark (
�
u):
+
2
3
+
3
2
e
Down quark (
�
d):
−
1
3
−
3
1
e
Charm quark (
�
c):
+
2
3
+
3
2
e
Strange quark (
�
s):
−
1
3
−
3
1
e
Top quark (
�
t):
+
2
3
+
3
2
e
Bottom quark (
�
b):
−
1
3
−
3
1
e
Where
�
e represents the elementary charge (
�
≈
1.602
×
1
0
−
19
e≈1.602×10
−19
Coulombs).
Now, let's consider various combinations of quarks and antiquarks to form mesons:
Quark-Antiquark Pair with Different Flavors:
When you combine a quark with an antiquark of a different flavor, their charges add up algebraically.
For example, a
�
�
ˉ
u
d
ˉ
pair would have a charge of
(
2
3
−
(
−
1
3
)
)
�
=
3
3
�
=
1
�
(
3
2
−(−
3
1
))e=
3
3
e=1e.
Similarly, any combination of different flavor quark-antiquark pairs will result in charges that are multiples of the elementary charge (
�
e), which are integral charges.
Quark-Antiquark Pair with the Same Flavor:
When you combine a quark with an antiquark of the same flavor, their charges will cancel out to zero.
For example, a
�
�
ˉ
u
u
ˉ
pair would have a charge of
(
2
3
−
2
3
)
�
=
0
�
(
3
2
−
3
2
)e=0e.
This also applies to other same-flavor quark-antiquark pairs, resulting in zero charge.
Since all combinations of quarks and antiquarks either produce integral charges or zero charges, mesons, which are composed of a quark-antiquark pair, will always have charges that are integral or zero. This is a fundamental property of the strong force and the quark model of particle physics.