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groups:journal_club:2011spring:week3

Search for Microscopic Black Hole Signatures at the Large Hadron Collider

The Paper

The .pdf file can be found here

An external link to the paper is here.

The DOI is

Discussion

I chose this paper as a follow up to the paper I presented last year (here). This paper sets the first experimental limits from the CMS collaboration to restrict the theories outlined in the previous paper (Which is reference [1] in this paper). This paper outlines a very simply search for microscopic black holes and and sets limits on their possible mass. The paper gets quite technical in the middle and although this is important to get feel for the analysis, do not get bogged down here.

The analysis is actually quite simply. The full proton-proton data set currently available was searched based on 2 variables S_{T} and N. S_{T} is the scalar sum of all jets, electrons, photons, muons, and MET above 50 GeV of transverse energy. N is the number of jets, electrons, photons, and muons above 50 GeV of transverse energy. This cut on transverse energy is put in place to limit the dijet background. Each difference combination of possible black hole mass and effective Plank Mass specific cuts are make on S_{T} and N. S_{T} is then plot and the remaining background is estimated by fitting region between 600 and 1100 GeV where no black holes are expected. The data above S_{T} > 1100 GeV is then inspected for excess over the background estimate. Black hole decay is also simulated and S_{T} calculated for comparison to the data. Finally a more general model independent search is done to restrict a broader range of models.

More information about the detector itself can be found here.

HEP Glossary

transverse energy - In hadron collides we are smashing composite particles and the energy is unevenly shared between the constituents. The hard collisions which happen between these constituents (called partons) which might create black holes therefore can have an arbitrary boost along the direction of travel of the beam. The momentum transverse to the beam momentum on the other hand is well constrained. This suggests the construction of the “transverse energy” which is the magnitude of the momentum transverse to the beam direction.

missing energy transverse (MET) - Certain particles such as neutrino (or possibly WIMPs or other super-symmetric particles if they exist) escape the detector without being detected. These particles cause energy to be missed. This is accounted for by the MET variable which is basically a 4-momentum which is used to cancel any excess traverse momentum.

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groups/journal_club/2011spring/week3.txt · Last modified: 2011/02/05 21:05 by pastika