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Extra dimensions vs. dark matter in the LHC 
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#1
Jun2109, 08:21 AM

P: 210

It is my understanding that physicists hope to use conservation of energy in the LHC to determine if there are multiple dimensions AND if there is dark matter. Let's suppose that through conservation of momentum, we detect a particle that apparently only reacts through gravity, and there is some amount of energy lost. Would we just E=mc˛ to determine how massive the particle is? What if more energy is lost via extra dimensions?



#2
Jun2109, 11:33 AM

P: 2,828

(*) For instance, you have a model predicting the existence of a spin 1/2 particle. Given the assumptions of this model, you calculate a crosssection. The angular decay in the restframe of your modeldependent particle is itself modelindependent (or better, depends not on the assumptions of your own model, but only on Lorentz invariance) 


#3
Jun2109, 11:51 AM

P: 210

So with all of that other information they can determine how much of the missing energy is actually the mass of the particle?



#4
Jun2109, 11:56 AM

P: 2,828

Extra dimensions vs. dark matter in the LHC



#5
Jun2109, 12:00 PM

P: 210

Huh, thanks! That's been bothering me for weeks.



#6
Jun2109, 12:46 PM

P: 2,828

Also, note a very general thing : IF you manage to find an example where even in principle you can NOT distinguish between the two final states (say missing particle VS extradimension), THEN the two processes interfere (you can not add crosssections, you must add the amplitudes). Typically, the production of your particle would be enhanced in some kinematical regions and suppressed somewhere else, due to extradimensions. Now in this case, it's not so trivial to make general statements. But you can already imagine that the dependencies become more complicated, say richer, and it's not impossible that you get a better handle on your parameters. But I expect that proponents of extradimensions would in any case like to cross check the results using another channel without this specific particle.



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