A blazing U.S. stock market rally left shares of energy companies behind in the first six months of 2023 as faltering global growth sapped expectations of oil demand. Some contrarian investors are betting a second half rebound may be in the works. While the U.S. economy has been more resilient than expected, weaker growth in the eurozone and China has weighed on oil prices, pushing Brent crude down about 16 per cent for the year. That has hurt shares of energy companies: after soaring in 2022, the S&P 500 energy sector has lost nearly 10 per cent this year, making…