No, a neutron cannot exist with only two quarks. Neutrons are composite particles made up of three quarks. Specifically, a neutron is composed of two down quarks and one up quark. The down quarks have a charge of -1/3 each, while the up quark has a charge of +2/3. The combination of these quarks results in a net charge of zero for the neutron.
The configuration of two down quarks and one up quark in a neutron is referred to as the udd quark composition. This composition is essential for maintaining the overall neutrality of the neutron. If a neutron were to have only two quarks, it would have an unbalanced charge, which would not be consistent with the properties of neutrons as observed in experiments.
It's important to note that quarks, being fundamental particles, cannot exist in isolation due to the nature of the strong nuclear force. They are always found in bound states, either within protons, neutrons, or other hadrons, or in combinations of quark-antiquark pairs known as mesons.