Hello!
This is a very interesting hand. There isn't much information on BB with only 14 hands but we can see his tendency to raise rather premium hands. Since he caps, I do expect him to have a monster or at least something like TT+, AQs+. UTG on the other hand is a VERY tight (10/7 over 500 hands) reg. Since he raises from UTG (although we do not gain any additional information about him preflop as he doesn't have the option of 5-betting) I do expect him to be pretty strong here as well.
Flop is very interesting as well. I actually wonder what your equity is on this flop vs. rather tight ranges, so let's see what equilator says.
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Operation completed... 395.514 games processed in 0 seconds.
Board: Ah Kh Js
Dead:
Equity Win Tie Loss Hand
Player 1: 19,259% 18,421% 1,963% 79,617% TT+, AQs+, AKo
Player 2: 61,482% 61,196% 0,859% 37,946% KsKd
Player 3: 19,259% 18,421% 1,963% 79,617% TT+, AQs+, AKo
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Operation completed... 698.922 games processed in 0 seconds.
Board: Ah Kh Js
Dead:
Equity Win Tie Loss Hand
Player 1: 16,189% 14,514% 3,638% 81,848% TT+, AQs+, AQo+
Player 2: 67,623% 67,334% 0,867% 31,799% KsKd
Player 3: 16,189% 14,514% 3,638% 81,848% TT+, AQs+, AQo+
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QT is pretty unlikely IMO so I did not include it in the ranges. It doesn't really matter if we include AQo or not, we are still a big favorite on the flop and the bet is of course a must.
Turn is quite interesting. The 6 of spades is a complete blank and after a raise from the UTG, I am 3-betting it with ease as I am still far ahead of his raising range IMO. BB gets out of the hand and UTG caps. This means that we have to narrow his range down. The only hands that I see him capping with here are AA and AK. Soo, let the equilator do it's job once again... 
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Operation completed... 6 games processed in 0 seconds.
Board: Ah Kh Js 6s 2h
Dead:
Equity Win Tie Loss Hand
Player 1: 50,000% 50,000% 0,000% 50,000% AA, AKs, AKo
Player 2: 50,000% 50,000% 0,000% 50,000% KsKd
Well, we have 50% EQ. If I understand this correct (which I probably don't so feel free to correct me :)), it does not really matter what we do anymore. We will win 50% of the times and lose 50% of the times. Since we generate more rake if we raise, it is probably better to just call the river bet? We will probably always get 3-bet by AA here (QT is not in our percieved range), I actually doubt it that we will get 3-bet by AK on this river so If I am correct, we actually need 66% EQ to make a profitable raise? I am a little out of shape when it comes to raising EQ etc.
