Update NSI oscillation source files, add stan support - #45
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chenel
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chenel
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Thanks for working with me on this.
I noticed one other thing, which is not your fault because it's from the preceding calculator code, but which needs to be addressed ASAP:
_OscCalcPMNS_NSI doesn't override GetParamsHash() from the base class. That means it inherits GetParamsHashDefault from _IOscCalcAdjustable, which only hashes the 8 standard oscillation parameters: fL, fRho, fDmsq21, fDmsq32, fTh12, fTh13, fTh23, fdCP (see IOscCalc.cxx:87-90). The 9 NSI-specific members (fEps_ee, ...) are silently excluded.
This means that any cache pull using GetParamsHash() will return stale results when only NSI parameters change---i.e., you'll get the same prediction for differing NSI parameters (😱).
We need an overridden GetParamsHash() in this class. Are you game for implementing it?
Adds 9 NSI matter potential parameters (eps_ee, eps_mumu, eps_tautau, eps_emu, eps_etau, eps_mutau with re/im components) to _OscCalc<T>. Modified _P() to include NSI contributions to the matter Hamiltonian: diagonal: A_CC * (1+eps_ee), A_CC * eps_mumu, A_CC * eps_tautau off-diagonal: A_CC * eps_emu, eps_etau, eps_mutau (complex) Verified with test_nsi_calc.C: both sections ALL PASS vs OscCalcPMNS_NSI.
The -E trick correctly handles complex off-diagonal NSI for antineutrinos. M is Hermitian, so P = |exp(M)_ba|^2 = |exp(M*)_ba|^2, and the physical antineutrino Hamiltonian is M^T = M* (Hermitian property), giving the same probability through |exp(M^T)_ba|^2 = |exp(M)_ab|^2 = |exp(M)_ba|^2. No explicit conjugation of imaginary eps parts is needed.
Implements analytic Cardano eigensolver for NSI oscillation probabilities, templated on T for Stan autodiff compatibility. NSI epsilon corrections are added to the matter Hamiltonian in UpdateHamiltonian() alongside the standard MSW term; GetEigenvalues() is untouched. Reverts NSI additions from OscCalcAnalytic base class — NSI is now in the standalone OscCalcAnalytic_NSI only, leaving the 3F base class unmodified.
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