context: Coming off their win over the Saints, the Panthers stayed at home for a Week 8 duel with the Arizona Cardinals.  In the first quarter, Carolina trailed early as Cardinals kicker Neil Rackers got a 21-yard field goal.  In the second quarter, Arizona increased its lead as QB Kurt Warner completed a 5-yard TD pass to WR Anquan Boldin.  The Panthers got on the board with kicker John Kasay getting a 23-yard field goal. In the third quarter, the Cardinals increased their lead as RB Tim Hightower got a 2-yard TD run.  Carolina started to rally as RB DeAngelo Williams got a 15-yard TD run, while QB Jake Delhomme completed an 18-yard TD pass to WR Steve Smith.  Arizona responded with Warner completing a 2-yard TD pass to Boldin (with a failed PAT), yet the Panthers got the lead with Delhomme hooking up with Smith again on a 65-yard TD pass.  In the fourth quarter, Carolina completed its rally as Kasay nailed a 50-yard field goal. With the win, the Panthers went into their bye week at 6-2.
question: How many more touchdowns were scored in the second half than the first?
answer: 4