Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Workload; Situational Awareness; Distraction; Communication Breakdown
ATC Issue All Types; Deviation / Discrepancy - Procedural Landing Without Clearance
Air Traffic Control Issued New Clearance
Human Factors
After landing and clearing Runway XXR at ZZZ we discovered comm 1 radio was still selected to Approach Control with ZZZ Tower frequency in the pre-select window.  On change over to Tower we were cleared to gate XX; and asked to call the Tower.  I was informed that we were given a green light from the Tower and they attempted to contact us on guard.  We did not see the Tower light signal and didn't hear them call on guard.  I was told everything was fine and they just wanted to know that we were on the same page.  I apologized and thanked them.1. We were in the midst of slowing the aircraft in order to achieve a stabilized approach and I must have become distracted as the call to change to Tower happened at the same time.    2. I should have had the radio volume set higher for comm 2.  3. End of a trans-con red-eye.  4. Both pilots have had minimal recent flying over the last few months.     More vigilance in monitoring guard frequency.  Positively confirm landing (and takeoff) clearances with other pilot.
Air carrier Captain reported landing without a landing clearance.