<p>Comfortable, casual and loose fitting, our heavyweight dark color t-shirt will quickly become one of your favorites. Made from 100% cotton, it wears well on anyone. We’ve double-needle stitched the bottom and sleeve hems for extra durability. Select a design from our marketplace or customize it to make it uniquely yours!</p>
<p>Size & Fit</p>
The Standard Model of particle physics is a theory of three of the four known fundamental interactions and the elementary particles that take part in these interactions. These particles make up all visible matter in the universe. Every high energy physics experiment carried out since the mid-20th century has eventually yielded findings consistent with the Standard Model. Still, the Standard Model falls short of being a complete theory of fundamental interactions because it does not include gravitation, dark matter, or dark energy. It is not quite a complete description of leptons either, because it does not describe nonzero neutrino masses, although simple natural extensions do.