Answer:
The B⁻ meson, also known as the "anti-bottom meson," consists of a bottom antiquark (
�
b) and a light antiquark. Its quark configuration is:
�
−
=
�
ˉ
+
�
B
−
=
b
ˉ
+q
Here:
�
ˉ
b
ˉ
represents the anti-bottom quark, which has an electric charge of
+
1
/
3
+1/3 (opposite in charge to the bottom quark).
�
q represents a light antiquark, which can be either an anti-up quark (
�
ˉ
u
ˉ
) or an anti-down quark (
�
ˉ
d
ˉ
). These light antiquarks have a charge of
−
1
/
3
−1/3.
The combination of the anti-bottom quark and a light antiquark results in a meson with an overall charge of
−
1
/
3
−
1
/
3
=
−
2
/
3
−1/3−1/3=−2/3. This charge makes it a
�
−
B
−
meson. It has a baryon number of zero, no strangeness, charm, or topness, and a bottomness of -1, as you mentioned.