A Lowell man has been charged with causing serious injury to his 2-month-old son, who was in critical condition at a Boston Hospital Sunday evening, according to authorities. Christopher Berry, 22, is scheduled to be arraigned in Lowell District Court Monday after being arrested and charged with assault and battery on a child causing substantial bodily injury, said a statement from the Middlesex County District Attorney’s office. Police, firefighters and paramedics from Lowell found Berry’s 2-month old son in an “unresponsive” state at 215 Mammoth Road on Saturday, the statement said. The infant’s injuries “are not consistent with accidental trauma,” prosecutors said. The boy was brought first to Lowell General Hospital, then to Tufts Floating Hospital for Children in Boston. As of Sunday evening, the child remained hospitalized in critical condition, authorities said. State Police assigned to the district attorney’s office and Lowell Police are continuing to investigate.