Generally, yes. Unpaid vacation is not the kind of wage or benefit that you earn in the same way as a wage, commission, retirement funds, etc. If you do not use it, your employer is not under any obligation to pay you for it unless it has a policy to do so.
This kind of information is often contained in an employee handbook, and is often covered in the documents provided upon hire.
However, just as with anything else, your employer may not deny you unused vacation pay in a discriminatory or retaliatory way. If your employer refuses to provide you with pay for unused vacation on the basis of your race/ gender/ religion/ sexual orientation, or inretaliation for complaining about unlawful workplace practices, it may be violating the law.
Further, Connecticut law requires that employers who do not pay out unused vacation time must make this information available it its employees either individually or in a posted notice, and this requirement applies to changes in the vacation policy as well.