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Determination of Higgs branching ratio into and

Determination of Higgs branching ratio into and. Grant Riley UTK-QFT 2012. Branching Ratio. Ratio of specific type of decay (channel) to total number of decays Also called decay rate Total decay width changes Based on number of possible Decay products. H ->ZZ. H ->WW. Branching Ratio.

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Determination of Higgs branching ratio into and

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  1. Determination of Higgs branching ratio into and Grant Riley UTK-QFT 2012

  2. Branching Ratio • Ratio of specific type of decay (channel) to total number of decays • Also called decay rate • Total decay width changes Based on number of possible Decay products H ->ZZ H ->WW

  3. Branching Ratio Differential Width is the percent of the total decay width that is made up of a certain channel Goal of this calculation

  4. Lagrangian

  5. Lagrangian Rotate through an angle in B, W space Plug into previous equation for Also knowing that the coefficient needs to equal eQ

  6. Lagrangian We can set eQ equal to the coefficient And solve

  7. Symmetry breaking This Lagrangian symmetry must be broken Choose a non zero vacuum expectation value for energy (v) Where

  8. Mass Acquisition We choose this gauge to keep the photon massless 4 degrees of freedom, 3 taken by the gauge bosons The 4th to be taken by the Higgs particle

  9. Feynman rules Branching diagrams with Feynman amplitude rules Feynman matrix element is M Branching ratio where is decay rate

  10. Matrix element ZZ Decay rate Identical products

  11. Matrix Element ZZ After some work

  12. Kinematic Restriction p and q are the 4 momenta of the two products By conservation of energy we can get

  13. Further Development Plugging in the restriction on energy Further reduction

  14. Decay Rate Plug this value for in the equation for the differential decay rate and take the integral To get

  15. Decay Rate WW This decay rate is exactly the same except for a factor of due to the Term which has n = 1 in the case because they are not identical products

  16. Final branching ratios

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