The reasons are complicated, and perhaps not entirely known yet. You can see a brief overview of what is known in the Wikipedia article "Color confinement".
During the particle era, quarks were confined within particles such as protons and neutrons. They did not exist freely as individual particles.
Protons and neutrons are composite particles make up of up and down quarks. There are two up quarks and one down quark in a proton, and two down quarks and an up quark in a neutron.
Quarks have been indirectly observed through particle accelerators and particle collision experiments, where their presence is inferred by the patterns of particles that are produced. Additionally, the properties of quarks, such as charge and spin, have been successfully predicted by the theory of Quantum Chromodynamics, providing further evidence for their existence.
There are no quarks in an electron. Electrons are leptons, which are not made of quarks. Further, the electron is a fundamental particle, just like the quark. That means that neither quarks or electrons are made up of other particles, per the Standard Model of particle physics.
There are six types of quarks known to exist: up, down, charm, strange, top, and bottom. They are fundamental particles that combine in different ways to form protons and neutrons, the building blocks of atomic nuclei.
Actually quarks can exist freely.
No, it is not possible ,a proton is the combination of two up and one down quarks but quarks do not exist freely.
In an atom, the neutrons and protons are made up of up quarks and down quarks. Strange quarks, charms quarks, top quarks, and bottom quarks also exist, but do not play as much of a role in the structure of an atom.
Every particle that should exist if quarks are real has been found. No particle that should not exist if quarks are real has ever been found. The results of in-elastic scattering between hadrons fits perfectly with quark. The hypothesis of charm quarks predicted experimental results that were almost perfectly replicated with the discovery of the psi-particle. In other words, the quark hypothesis matches observation perfectly. That's about as strong of evidence as can exist.
During the particle era, quarks were confined within particles such as protons and neutrons. They did not exist freely as individual particles.
No, they are now solid fact. Quarks are the fundamental particles which make up the protons and neutons of everything around us, as well as some other crazy particles such as the Higgs boson. There are some bosons (things made up of quarks) which are merely theoretical; we know they muct exist but have not yet found one, but quarks are definitely NOT fictional
Yes, quarks exist, and they have been demostrated in particle accelerators in the high energy physics laboratory.
Quarks have not been observed to exist separately - they are "confined" within larger particles such as protons and neutrons, that are made up of several quarks (3 each, in the case of protons and neutrons).
Protons and neutrons are composite particles make up of up and down quarks. There are two up quarks and one down quark in a proton, and two down quarks and an up quark in a neutron.
the better question is..... why DONT we exist
Quarks have been indirectly observed through particle accelerators and particle collision experiments, where their presence is inferred by the patterns of particles that are produced. Additionally, the properties of quarks, such as charge and spin, have been successfully predicted by the theory of Quantum Chromodynamics, providing further evidence for their existence.
There are no quarks in an electron. Electrons are leptons, which are not made of quarks. Further, the electron is a fundamental particle, just like the quark. That means that neither quarks or electrons are made up of other particles, per the Standard Model of particle physics.