By Greg Roumeliotis and Nadia Damouni NEW YORK (Reuters) – Private equity firms Hellman & Friedman LLC and JMI Equity are exploring a sale of human resources management software firm Kronos Inc, which could be valued at more than $4 billion, people familiar with the matter said on Wednesday. Kronos is in early-stage talks with a small group of private equity firms, including KKR & Co LP, TPG Capital LP and Bain Capital LLC, about a potential deal, the people said. Oracle Corp and SAP AG would be natural buyers for Kronos but have so far shown little interest, the people added.