The Mahdi (as) and Occultation in the Shia Imami Alevi-Bektashi Tariqah

Salam and Hu Dost!

Do Shia Imami Alevi-Bektashi Muslims believe that the son of Imam Hasan al-Askari (as) is the Mahdi (as)? Is it also believed that he went into Ghaybah (Occultation)?

If not, then who is the current Imam, and will the Madhi (as) be born in the future?