Alia Bhatt, Siddharth Malhotra at Arjun Kapoor's birthday bash

The co-stars of the 2012 Karan Johar film 'Student of the Year' - Alia Bhatt & Siddharth Malhotra arrived for the big bash thrown by Sonam Kapoor, for cousin Arjun's 28th birthday.

Alia and Arjun are currently working on their film '2 States' which is an adaptation of Chetan Bhagat's novel of the same name.