Chinanews, Beijing, March 27 - Twice Olympic champion Tian Liang has retired despite China missing out on gold in his event at the world championships, local media reported on Tuesday.The 27-year-old "diving prince" won two Olympic golds, three world titles and 15 World Cups in his career.Tian's provincial Shaanxi sports bureau chief confirmed he had retired to state Xinhua news agency.