JPMorgan Chase Chief Executive Jamie Dimon met with Zohran Mamdani on Monday as the New York City mayor seeks to tamp down the backlash to his “tax the rich” proposal that rankled many of the city’s wealthy. Mamdani, who calls himself a democratic socialist, went to JPMorgan Chase’s new headquarters at 270 Park Avenue for a noon meeting with the billionaire Dimon. During the meeting, the two discussed cutting government waste, the reform of state environmental reviews for building, and public-private partnerships, according to a city spokesman.