Ben beat me to it with his Halyard suggestion. Its weight is a touch on the heavy side, but Helvetica comes in many weights. Halyard has the descender on the capital G (as opposed to Arial that doesn't) but Halyard has a stylised capital Q.
If you have been using Photoshop for a while, then a trick I have had to resort to is reinstall CS6 and grab a copy of fonts that became discontinued with later versions. Be aware that fonts come and go with Adobe. Brickham Script is an example of a font I had to rescue from CS6, but it appears to be now be available again. I back up my entire font folder when changing hardware, to guard against such occurrences. Take nothing for granted.