Why LHC Higher Energy: Advantage in Higgs Search

[phrygian]

What is the advantage of the higher energy of the LHC for finding the Higg's when Tevatron was already operating at an energy significantly higher than the predicted Higgs mass? Is it just that higher energy collisions will result in more particles, making data collection faster?

 

[Bill_K]

They made the LHC energy as high as could be handled in the existing tunnel. Surely you would not want to spend $6B and then realize the energy was a bit short! Anyway, finding the Higgs boson is not the only goal, we want to survey as much territory as we can for new physics.

 

[Parlyne]

The advantage comes from the fact that proton are composite particles and at the high energies involved in the collisions what actually matters is the energy carried by the partons (quarks or gluons) that actually collide. This is generically quite a bit smaller than the total energy in the collision. So, at the LHC a significantly larger fraction of collisions should have enough energy to produce a Higgs than at the Tevatron. This effect is further pronounced by the fact that the Higgs is, by far, most readily produced in conjunction with other heavy particles.

 

[Drakkith]

Does the LHC accelerate and collide a greater number of particles on average than the Tevatron?

 

[Bill_K]

Slightly more. The peak instantaneous luminosity at the Tevatron was 4 x 10³²/cm²/s. So far the LHC has achieved 10³³/cm²/s, and its design luminosity is 10³⁴.

 

[Drakkith]

Slightly? Isn't that like ten times as much with a design of up to 100x more? (Is the LHC 1x10^33 or 4x10^33?) Or is my math wrong?

 

[Vanadium 50]

Yes, because it's a proton-proton collider. The Tevatron is proton-antiproton, so you have to make antiprotons. That limits the collision rate.

 

[Drakkith]

I see. Thanks!