Neutrons consist of one up quark and two down quarks. Mills equations for quark and gluon fields. Ordinary mesons are made up of a valence quark and a valence antiquark. Each pion consists of a quark and an antiquark and is therefore a meson. It is made up of two strange quarks and a bottom quark. There may be hadrons which lie outside the quark model. The charge of each antiquark is exactly the opposite of the corresponding quark. The presence of these condensates characterizes the confined phase of quark matter. Positron emission happens when an "up" quark changes into a "down" quark. The discovery finally convinced the physics community of the quark model's validity. The only exception is the top quark, which may decay before it hadronizes. GeV for the mass of the top quark. This theoretical model required the existence of the as-yet undiscovered charm quark. Color confinement is verified by the failure of free quark searches (searches of fractional charges). Polish pierogi are often filled with fresh quark, boiled and minced potatoes, and fried onions.