The Science of Happiness and Positive Psychology

Happiness has been an object of scientific study by psychologists and it is now becoming an object of study by economists as well. From the psychologist angle, a nice book that I recommend 100% is Authentic Happiness by Martin Seligman. An interesting article is Happiness 101
If you are interested in the mathematical modeling of happiness, you may want to look at the book chapter I'm writing with Rakesh Sarin, a colleague from UCLA, and available in my research web page.