Town of Braintree (Mass.) Employees Retirement System Dec. 14 will interview finalists for a core domestic fixed-income manager to run a $20 million portfolio. The finalists are Allmerica Asset Management, Sirach Capital, State Street Research and Wellington, said Jennifer Miller, retirement clerk. The $85 million system hopes to pick a new manager on Dec. 20. The search follows an asset allocation study. New England Pension Consultants is assisting.