Neutrino decays, Majoron channels and coherence
Calculate the included heavy-neutrino partial widths and conditional lifetime, flight-window and isolated-pair coherence diagnostics.
Control names are kept as they appear in the application. Start with a reference, change one input at a time, and retain the assumptions with your result.
What this tool is for
Use this to see how specified decay assumptions affect lifetime and coherence. The controls make missing channels visible as assumptions rather than silently setting a complete width. Optional leading Majoron contributions have their own calculation and validity conditions.
First steps
- Select a heavy pair in the Neutrino ring mode.
- Read which weak channels are open, and choose whether to include the computed Majoron widths.
- Set any additional width as an explicit scenario input.
- Choose the boost and flight window, then read the probability separately from the all-time coherence ratio.
Controls and inputs
| Control | Meaning | Try this |
|---|---|---|
| Heavy-pair selection | Chooses the mass, active weight and splitting used in the decay scenario. | Select a pair from the channel bars or use the supported keyboard controls. |
| Computed Majoron channels and scalar VEV ratios | Enable the included leading light and heavy-cascade Majoron widths under the stated scalar assumptions. | Compare enabled and disabled values without interpreting disabled as physically absent. |
| Additional width | An input contribution in eV representing an assumed uncomputed width. | Increase it and observe how the conditional lifetime changes. |
| βγ, Lmin and Lmax | A fixed boost and straight-line distance window in the displayed units. | Move the window while keeping the decay scenario fixed. |
Reading the results
| Result | Meaning |
|---|---|
| Partial widths and lifetime | The included width sum gives τ = ℏ/Γ for the chosen scenario. A zero included sum does not prove stability. |
| Flight probability | The probability to decay in the chosen straight-line window at one fixed boost; it is not an event yield. |
| SS/OS and same-sign fraction | Distinct ideal-coherence quantities under isolated-pair, equal-width and CP assumptions. |
The displayed width belongs to one component of a heavy pair. The complete physical ring width remains unknown. A flight-window probability is not detector acceptance, and the all-time same-sign/opposite-sign ratio is not a selected-event ratio.
Worked example
See how a missing-channel assumption changes a prediction
- Select one pair and record the included width and lifetime.
- Enable the computed Majoron contribution where supported.
- Add a small explicit extra-width scenario and compare again.
- Read the flight probability and the coherence warning separately.
What to expect: Lifetime and coherence depend on the included channels. The controls explore that dependence rather than determining the unknown complete width.
Formulas and conventions
P = exp[−Lmin/(βγ cτ)] − exp[−Lmax/(βγ cτ)]
The fixed-boost straight-line window probability in this scenario.
SS/OS = Δm² / (2Γ² + Δm²)
The all-proper-time isolated coherent-pair result under the stated equal-width and CP assumptions.
Scope and limitations
- Off-shell weak processes, additional scalar/gauge channels and unresolved corrections can change the complete width.
- Near-degenerate different pairs can invalidate isolated-pair reasoning.
- Detector efficiencies, boost distributions and event selections are not included.
If something is unclear
The lifetime or probability is undefined.
Check whether the included width is zero or the inputs are out of scope; do not label the state stable.
A coherence warning appears.
Read the width, insertion and inter-pair-gap diagnostics before using the isolated-pair ratio.
Terms used here
Sources and attribution
Current instrument guide. Archived editions retain their own scope.
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