BOSTON-Next Sunday, some 800 people, mostly families with roots in West Africa, will descend on Boston for a “bayan,” a Fulani word that describes a long talk followed by questions from the community. Their host will be Sheikh Mamadou Taibou Ba, 34, considered by some to be a wunderkind among Islamic scholars. Many of the questions posed to Ba on his U.S. tour focus on what is “halal” (permitted) and what is “haram” (forbidden). Hair implants and mixed-gender dancing both fall into the latter category, he says. But the story behind Ba is less about him and more about what he represents-a tradition of West African Islam that observers say is more moderate and less anti-American than in other parts of the Islamic world. What’s more, this brand of West African Islam is being showered with interest, especially among Muslim Americans (who account for roughly one third of all U.S. Muslims) and is helping shape their views of Islam.