Effects of the fourth generation on <img src="/fulltext-image.asp?format=htmlnonpaginated&src=KHYB3CLELMT3TRW5_html\" border="0" alt="$\Delta M_{B_{d,s}}$" /> in <img src="/fulltext-image.asp?format=htmlnonpaginated&src=KHYB3CLELMT3TRW5_html\" border="0" alt="$B^0$" />– <img src="/fulltext-image.asp?format=htmlnonpaginated&src=KHYB3CLELMT3TRW5_html\" border="0" alt="$\bar B^0$" /> mixing

Abstract.: We investigate the mass differences in – mixing with a new up-like quark in the sequential fourth generation model. We give the basic formulae for in this model and obtain two kinds of numerical results for as a function of . We find that one of our results can satisfy the present experimental lower bound of . We also get the constraints of the fourth generation CKM factor , as a function of , from the experimental measurements of . Thus, provides a possible test of the fourth generation and may give a signal of new physics.