Difference between revisions of "Invisible decay"
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</table> | </table> | ||
+ | ==Three-pion acceptance is considered== | ||
+ | [[File:First try study eta acceptance.pdf|first try of taking three-pion decay modes into consideration]] | ||
==Reference== | ==Reference== | ||
arxiv:1209.2469 | arxiv:1209.2469 |
Revision as of 17:07, 8 September 2014
Idea
B(inivisible)/B(normalization)={N(upper limit)/efficiency(invisible)}/{N(normalization)/efficiency(normalization)} * {1/(1-sigma)}
- B(inivisible): branching ratio of the invisible decay
- B(normalization): branching ratio of the reference channel
- N(upper limit): upper limit of the yield of the invisible decay
- N(normalization): yield of the reference channel
- efficiency(invisible): acceptance of the invisible decay
- efficiency(normalization): acceptance of the reference channel
- sigma: systematic uncertainty
What applies here:
The channel we are using is : gamma p -> p eta_prime -> p pi+ pi- (eta). The invisible decay of eta is eta -> xx. x is something like U boson, which could be dark photon or heavy photon.
B(normalization) is 1 when we obtain eta by requiring the missing mass.
efficiency(invisible)=efficiency(normalization) * efficiency (invisible decay of eta). efficiency(normalization) is the detection efficiency of p pi+ pi-. efficiency(invisible) is the product of efficiency(normalizaiton) and efficiency(invisible decay of eta). efficiency(invisible decay) is the detection efficiency of at least one photon from eta decay.
photon detection efficeincy
procedure
- collection events of p, pi+, pi- and one or two photons
- requiring the missing mass of p pi+ pi- to be pi0
- requiring the missing mass of p to be eta or omega
- events passing the above three conditions are called "all" events
- two-photon events are called "good" events
- the ratio of "good" events to "all" events is the detection efficiency of photon
- the ratio is binned in energy, theta, and phi angle in lab frame
result
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Eta acceptance
partial statistics
The following is from 2% of the data.
Different efficiency
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Compare expected and no-photon detected
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Study of the difference
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Three-pion acceptance is considered
File:First try study eta acceptance.pdf
Reference
arxiv:1209.2469