Difference between revisions of "Invisible decay"
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===Compare events from CMU and JLab=== | ===Compare events from CMU and JLab=== | ||
First line is JLab data, second line is CMU kinfit result | First line is JLab data, second line is CMU kinfit result | ||
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run# event# proton.px py pz pip.px py pz pim.px py pz photon.eid photon.energy | run# event# proton.px py pz pip.px py pz pim.px py pz photon.eid photon.energy | ||
43634 7520 -0.218356 0.252237 0.850728 0.219179 -0.719475 1.00864 0.099808 -0.17973 0.341651 23 3.75253 | 43634 7520 -0.218356 0.252237 0.850728 0.219179 -0.719475 1.00864 0.099808 -0.17973 0.341651 23 3.75253 | ||
+ | |||
43634 7520 0.219289 -0.723163 1.01175 -0.22012 0.247369 0.848749 0.0987671 -0.179789 0.342487 23 3.76824 | 43634 7520 0.219289 -0.723163 1.01175 -0.22012 0.247369 0.848749 0.0987671 -0.179789 0.342487 23 3.76824 | ||
<hr> | <hr> | ||
43634 14658 0.0711455 -0.20281 0.597634 -0.104869 0.152357 0.275508 -0.199497 -0.0941665 0.0464326 638 1.35182 | 43634 14658 0.0711455 -0.20281 0.597634 -0.104869 0.152357 0.275508 -0.199497 -0.0941665 0.0464326 638 1.35182 | ||
+ | |||
43634 14658 0.0715849 -0.204999 0.602069 -0.105456 0.151199 0.276457 -0.199497 -0.094166 0.0464326 275 2.79164 | 43634 14658 0.0715849 -0.204999 0.602069 -0.105456 0.151199 0.276457 -0.199497 -0.094166 0.0464326 275 2.79164 | ||
<hr> | <hr> | ||
43634 14953 0.176975 -0.487071 1.02445 -0.228198 -0.0155644 0.203839 0.176574 0.267612 0.14746 485 1.9536 | 43634 14953 0.176975 -0.487071 1.02445 -0.228198 -0.0155644 0.203839 0.176574 0.267612 0.14746 485 1.9536 | ||
+ | |||
43634 14953 0.178628 -0.490327 1.02955 -0.228806 -0.0163596 0.204688 0.177539 0.268025 0.149043 225 2.9897 | 43634 14953 0.178628 -0.490327 1.02955 -0.228806 -0.0163596 0.204688 0.177539 0.268025 0.149043 225 2.9897 | ||
==Reference== | ==Reference== | ||
arxiv:1209.2469 | arxiv:1209.2469 |
Revision as of 18:59, 17 October 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
Eta acceptance
partial statistics
The following is from 2% of the data.
Different efficiency
Compare expected and no-photon detected
Study of the difference
Three-pion acceptance is considered
File:First try study eta acceptance.pdf
File:Compare seen expected.pdf
File:Second try study eta acceptance.pdf
This results yield 3e-3 upper limit.
Compare events from CMU and JLab
First line is JLab data, second line is CMU kinfit result
run# event# proton.px py pz pip.px py pz pim.px py pz photon.eid photon.energy
43634 7520 -0.218356 0.252237 0.850728 0.219179 -0.719475 1.00864 0.099808 -0.17973 0.341651 23 3.75253
43634 7520 0.219289 -0.723163 1.01175 -0.22012 0.247369 0.848749 0.0987671 -0.179789 0.342487 23 3.76824
43634 14658 0.0711455 -0.20281 0.597634 -0.104869 0.152357 0.275508 -0.199497 -0.0941665 0.0464326 638 1.35182
43634 14658 0.0715849 -0.204999 0.602069 -0.105456 0.151199 0.276457 -0.199497 -0.094166 0.0464326 275 2.79164
43634 14953 0.176975 -0.487071 1.02445 -0.228198 -0.0155644 0.203839 0.176574 0.267612 0.14746 485 1.9536
43634 14953 0.178628 -0.490327 1.02955 -0.228806 -0.0163596 0.204688 0.177539 0.268025 0.149043 225 2.9897
Reference
arxiv:1209.2469