C9.cpp

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#include <iostream>
#include <string>
 
// HYPERISO_MARTY_OPERATOR_NORM_ABI: ew-input-normalization-v1
// HYPERISO_MARTY_TEMPLATE_ABI: semileptonic-c9-tree-first-split-regprop-fresh-loop-model-v17
using namespace csl;
using namespace mty;
using namespace std;
using namespace sm_input;
 
namespace {
 
enum class HyperisoMartyC9LinkerSelection {
    NonPhotonVector,
    PhotonOnly
};
 
HyperisoMartyC9LinkerSelection hyperiso_marty_c9_linker_selection =
    HyperisoMartyC9LinkerSelection::NonPhotonVector;
 
void hyperiso_marty_set_c9_linker_selection(HyperisoMartyC9LinkerSelection selection) {
    hyperiso_marty_c9_linker_selection = selection;
}
 
bool hyperiso_marty_tree_level_matching = false;
 
void hyperiso_marty_set_semileptonic_order(mty::Order order) {
    hyperiso_marty_tree_level_matching = (order == mty::Order::TreeLevel);
}
 
bool hyperiso_marty_is_photon_name(std::string const& name) {
    return name == "A" || name == "A;\\gamma" || name.find("\\gamma") != std::string::npos;
}
 
bool hyperiso_marty_is_scalar_particle(const mty::Particle& particle) {
    return particle->getSpinDimension() == 1;
}
 
bool hyperiso_marty_is_photon_linker_particle(const mty::Particle& particle) {
    return hyperiso_marty_is_photon_name(std::string(particle->getName()));
}
 
bool hyperiso_marty_is_forbidden_c9_linker_particle(const mty::Particle& particle) {
    // Raw photon linkers A -> l+l- carry the regulated propagator used by
    // MARTY's 4-fermion penguin patch.  They are not a finite C9/CP9 matching
    // coefficient.  Finite photon pieces must be supplied analytically or via
    // WilsonMatchingPatch.  This does not veto particles inside loops, only the
    // linker that MARTY connects to the lepton current.
    if (hyperiso_marty_is_photon_linker_particle(particle)) {
        return true;
    }
 
    // Neutral scalar/Goldstone linkers can be present as External particles of
    // the penguin sub-amplitude before MARTY connects the 4-fermion graph. They
    // should not be projected onto vector C9/CP9; scalar effects belong to CQ*
    // operators.  Again, this does not remove scalar BSM particles in loops or
    // boxes, only a scalar linker attached to the lepton current.
    if (hyperiso_marty_is_scalar_particle(particle)) {
        return true;
    }
 
    return false;
}
 
template <typename Predicate>
bool hyperiso_marty_has_linker_matching(mty::FeynmanDiagram const& diag, Predicate predicate) {
    // In MARTY's 4-fermion coefficient construction, the penguin linker X in
    // b -> s X is still an External particle when diagram filters are applied.
    // After connectAmplitudes(), it may appear as a Mediator.  Check both;
    // checking Mediator only misses A/G0 and leaves reg_prop-dependent terms.
    for (const auto& particle : diag.getParticles(mty::FeynmanDiagram::DiagramParticleType::External)) {
        if (predicate(particle)) {
            return true;
        }
    }
    for (const auto& particle : diag.getParticles(mty::FeynmanDiagram::DiagramParticleType::Mediator)) {
        if (predicate(particle)) {
            return true;
        }
    }
    return false;
}
 
bool hyperiso_marty_has_photon_linker(mty::FeynmanDiagram const& diag) {
    return hyperiso_marty_has_linker_matching(diag, [](const mty::Particle& particle) {
        return hyperiso_marty_is_photon_linker_particle(particle);
    });
}
 
bool hyperiso_marty_has_forbidden_c9_linker(mty::FeynmanDiagram const& diag) {
    return hyperiso_marty_has_linker_matching(diag, [](const mty::Particle& particle) {
        return hyperiso_marty_is_forbidden_c9_linker_particle(particle);
    });
}
 
bool hyperiso_marty_accept_c9_linker(mty::FeynmanDiagram const& diag) {
    // Linker filtering is a one-loop penguin policy.  At tree level a scalar
    // leptoquark mediator is a legitimate source of C9 after operator
    // projection/Fierz rearrangement and must not be mistaken for a neutral
    // scalar penguin linker.
    if (hyperiso_marty_tree_level_matching) {
        return true;
    }
    switch (hyperiso_marty_c9_linker_selection) {
        case HyperisoMartyC9LinkerSelection::NonPhotonVector:
            return !hyperiso_marty_has_forbidden_c9_linker(diag);
        case HyperisoMartyC9LinkerSelection::PhotonOnly:
            return hyperiso_marty_has_photon_linker(diag);
    }
    return !hyperiso_marty_has_forbidden_c9_linker(diag);
}
 
// Backward-compatible aliases: older generated caches/templates called these
// names. Keeping aliases prevents one half-updated template from failing to
// compile.  The semantically precise helper is hyperiso_marty_has_photon_linker.
bool hyperiso_marty_has_forbidden_c9_penguin_mediator(mty::FeynmanDiagram const& diag) {
    return hyperiso_marty_has_forbidden_c9_linker(diag);
}
 
bool hyperiso_marty_has_photon_mediator(mty::FeynmanDiagram const& diag) {
    return hyperiso_marty_has_photon_linker(diag);
}
 
} // namespace
 
void defineLibPath(Library &lib) {
#ifdef MARTY_LIBRARY_PATH
    lib.addLPath(MARTY_LIBRARY_PATH);
    lib.addLPath(MARTY_LIBRARY_PATH "/..");
    lib.addLPath(MARTY_LIBRARY_PATH "/marty");
    lib.addLPath(MARTY_LIBRARY_PATH "/marty/lha");
#endif
#ifdef MARTY_INCLUDE_PATH
    lib.addIPath(MARTY_INCLUDE_PATH);
#endif
}
 
int calculate_C9mu(Model &model, gauge::Type gauge) {
 
    model.getParticle("W")->setGaugeChoice(gauge);
    model.getParticle("Z")->setGaugeChoice(gauge);
 
    undefineNumericalValues(); // Allow for HIso to set all the parameters' values
    mty::option::excludeExternalLegsCorrections = false;
 
    Expr factorOperator = -4 * GetComplexConjugate(V_ts) * V_tb * G_F * pow_s(e_em / (4 * CSL_PI), 2) / csl::sqrt_s(2);
    FeynOptions opts;
    // The photon-penguin part of b -> s l l is not used directly as the final
    // C9 four-fermion coefficient because it carries MARTY's regulated photon
    // propagator.  In BSM-split mode the same template is evaluated twice:
    //   - NonPhotonVector -> exported as C9 and evaluated numerically
    //                       with reg_prop = 1e-6.
    //   - PhotonOnly      -> exported separately as C9_A and evaluated
    //                       numerically with reg_prop = 1.
    // The numeric wrapper writes C9 = C9_non-photon + C9_A.
    opts.addFilter([](mty::FeynmanDiagram const& diag) {
        return hyperiso_marty_accept_c9_linker(diag);
    });
    opts.setFermionOrder({1, 0, 2, 3});
    opts.setWilsonOperatorCoefficient(factorOperator);
 
    auto wil = model.computeWilsonCoefficients(
        mty::Order::OneLoop,
        {Incoming("b"), 
         Outgoing("s"),
         Outgoing("mu"),
         Outgoing(AntiPart("mu"))},
        opts
    );
    
    Expr C9_mu = getWilsonCoefficient(
        wil, 
        dimension6Operator(model, wil, DiracCoupling::VL, DiracCoupling::V)
    );
    
    [[maybe_unused]] int sysres = system("rm -rf libs/C9_SM");
    mty::Library wilsonLib("C9_SM", "libs");
    wilsonLib.cleanExistingSources();
    wilsonLib.addFunction("C9", C9_mu);
    defineLibPath(wilsonLib);
    wilsonLib.print();
 
    return 0;
}
 
int main() {
    SM_Model sm;
    return calculate_C9mu(sm, gauge::Type::Feynman);
}