Difference between revisions of "UMICH-2015: Neutrino and Light Relativisic Species break-out session 1"

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[[UMICH-2015: Neutrino and Light Relativisic Species|Return to Neutrino and Light Relativisic Species sessions page]]
 
[[UMICH-2015: Neutrino and Light Relativisic Species|Return to Neutrino and Light Relativisic Species sessions page]]
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;Clear science target - A massless field in thermal equilibrium with the Standard model leads to &Delta;N<sub>eff</sub> > 0.027
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;For thermal decoupling above 100 GeV :
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: a real scalar produces &Delta;N<sub>eff</sub> = 0.027
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: a Weyl fermion produces &Delta;N<sub>eff</sub> = 0.047 (Dirac : 0.094)
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: a vector field produces &Delta;N<sub>eff</sub> = 0.054
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;With 10<sup>6</sup> detectors and f<sub>sky</sub> = 0.75, forecasts of &sigma;<sub>Neff</sub> =0.013 (see e.g. arXiv:1402.4108).
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: Model independent theory motivation - Is this realistic experimentally?
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;More general science targets -- axion-like particles, late decays of massive fields (before or after BBN), decaying Dark matter
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: How well can be break degeneracies?
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:: E.g. Want to separate N<sub>eff</sub><sup>CMB</sup> from Y<sub>p</sub>
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:: Forecasts with both varying give &sigma;<sub>Neff</sub> = 0.048 and &sigma;<sub>Yp</sub> = 0.0027 (see arXiv:1508.06342)
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:: In principle allows us to distinguish effects at recombination from changes to BBN
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: What role does CMB lensing play?
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:: For N<sub>eff</sub>, delensing E-modes improves constraints significantly
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:: Can it help break degeneracies in other models (e.g. decaying dark matter) ?

Revision as of 13:56, 17 September 2015

Wiki navigation

Return to main workshop page

Return to Neutrino and Light Relativisic Species sessions page

Clear science target - A massless field in thermal equilibrium with the Standard model leads to ΔNeff > 0.027
For thermal decoupling above 100 GeV 
a real scalar produces ΔNeff = 0.027
a Weyl fermion produces ΔNeff = 0.047 (Dirac : 0.094)
a vector field produces ΔNeff = 0.054
With 106 detectors and fsky = 0.75, forecasts of σNeff =0.013 (see e.g. arXiv
1402.4108).
Model independent theory motivation - Is this realistic experimentally?
More general science targets -- axion-like particles, late decays of massive fields (before or after BBN), decaying Dark matter
How well can be break degeneracies?
E.g. Want to separate NeffCMB from Yp
Forecasts with both varying give σNeff = 0.048 and σYp = 0.0027 (see arXiv:1508.06342)
In principle allows us to distinguish effects at recombination from changes to BBN
What role does CMB lensing play?
For Neff, delensing E-modes improves constraints significantly
Can it help break degeneracies in other models (e.g. decaying dark matter) ?