EventInfo< Muon, Photon >

Description

template<class Muon, class Photon>
struct DAS::Unfolding::ZmmY::EventInfo< Muon, Photon >

Implements the event selection and categorization common to all ZmmY observables, and saves some relevant intermediate calculations.

Template Parameters

Muon	Only prepared to handle muons (gen or rec)
Photon	Gen or rec photons

#include <ZmmYCommon.h>

Collaboration diagram for EventInfo< Muon, Photon >:

Public Member Functions
	EventInfo ()
	EventInfo (const GenEvent *gEv, const RecEvent *rEv, const std::vector< Muon > &muons, const std::vector< Photon > &photons, const Uncertainties::Variation &v)

Public Attributes
EventCategory	category
Di< const Muon, const Muon >	dimuon
float	mMuMu
std::vector< Photon >	selectedPhotons
float	mMuMuGamma
float	weight

Static Public Attributes
constexpr static double	minMuon0Pt = 20
constexpr static double	minMuon1Pt = 15
constexpr static double	maxMuonEta = 2.4
constexpr static double	minPhotonPt = 20
constexpr static double	maxPhotonEta = 2.4
constexpr static double	minZMass = 76
constexpr static double	maxZMass = 106
constexpr static double	minMuMuMass = 40

Private Member Functions
bool	IsMassOnZPeak (float mass) const
DAS::Di< const Muon, const Muon >	SelectMuons (const std::vector< Muon > &muons, const Uncertainties::Variation &v) const
bool	IsGoodPhoton (const RecPhoton &photon, const Uncertainties::Variation &v) const
bool	IsGoodPhoton (const GenPhoton &photon, const Uncertainties::Variation &v) const

Constructor & Destructor Documentation

EventInfo() [1/2]

EventInfo ( )

inline

Default constructor to enable use as a variable in fillers.

        : category(EventCategory::NotSelected)
        , selectedPhotons{}
        , mMuMu(-1)
        , mMuMuGamma(-1)
        , weight(0)
    {
    }

EventInfo() [2/2]

EventInfo	(	const GenEvent *	gEv,
		const RecEvent *	rEv,
		const std::vector< Muon > &	muons,
		const std::vector< Photon > &	photons,
		const Uncertainties::Variation &	v
	)

Main constructor.

Todo:

We may need to reorder photons after the variation.

Todo:

We only consider the leading photon for now.

Parameters

gEv	Null for data.
rEv	Null for gen-level.

    : EventInfo()
{
    weight = 1;
    if (rEv) weight *= rEv->Weight(v);
    if (gEv) weight *= gEv->Weight(v);
 
    // Start by looking at muons.
    dimuon = SelectMuons(muons, v);
    if (!dimuon) return;
 
    mMuMu = dimuon.CorrP4(v).M();
 
    // The dimuon system is on the Z peak. Don't consider photons.
    if (IsMassOnZPeak(mMuMu)) {
        category = EventCategory::MuMu;
        weight *= dimuon.Weight(v);
        return;
    }
 
    // Do not consider muon pairs below minMuMuMass. This reduces
    // backgrounds (e.g. vector meson + gamma).
    // We also remove here events with mMuMu above the Z peak, as there is
    // no way adding photons can bring them back to the peak.
    if (mMuMu < minMuMuMass || mMuMu > minZMass)
        return;
 
    // Now get photons. We must copy them because the photons collection could
    // be reused with another variation.
    std::copy_if(photons.begin(), photons.end(),
                    std::back_inserter(selectedPhotons),
                    [&] (auto photon) { return IsGoodPhoton(photon, v); });
 
    if (selectedPhotons.empty()) return;
 
    mMuMuGamma = (dimuon.CorrP4(v) + selectedPhotons[0].CorrP4(v)).M();
    if (IsMassOnZPeak(mMuMuGamma)) {
        category = EventCategory::MuMuGamma;
        weight *= dimuon.Weight(v) * selectedPhotons[0].Weight(v);
    }
}

Member Function Documentation

IsGoodPhoton() [1/2]

bool IsGoodPhoton ( const GenPhoton &  photon, const Uncertainties::Variation &  v  ) const

inlineprivate

Checks if a generated photon passes the selection criteria.

    {
        auto p4 = photon.CorrP4(v);
        return photon.Weight(v) != 0
            && photon.zAncestor
            && p4.Pt() > minPhotonPt && std::abs(p4.Eta()) < maxPhotonEta;
    }

IsGoodPhoton() [2/2]

bool IsGoodPhoton ( const RecPhoton &  photon, const Uncertainties::Variation &  v  ) const

inlineprivate

Checks if a reconstructed photon passes the selection criteria.

Todo:

Use a \( \Delta R \) cut w.r.t. muons?

    {
        auto p4 = photon.CorrP4(v);
        return photon.Weight(v) != 0
            && p4.Pt() > minPhotonPt && std::abs(p4.Eta()) < maxPhotonEta;
    }

IsMassOnZPeak()

bool IsMassOnZPeak ( float  mass ) const

inlineprivate

Checks if a mass should be considered close to the Z peak.

    {
        return mass > minZMass && mass < maxZMass;
    }

SelectMuons()

DAS::Di<const Muon, const Muon> SelectMuons ( const std::vector< Muon > &  muons, const Uncertainties::Variation &  v  ) const

inlineprivate

Selects a pair of muons, if any. Returns a null Di if no suitable pair is found.

Todo:

The variation could change which muons are leading.

    {
        if (muons.size() < 2) return {};
 
        const auto& m0 = muons[0],
                  & m1 = muons[1];
 
        const auto p0 = m0.CorrP4(v),
                   p1 = m1.CorrP4(v);
 
        if (m0.Q * m1.Q != -1 // opposite charges
            || p0.Pt() < minMuon0Pt
            || p1.Pt() < minMuon1Pt
            || abs(p0.Eta()) >= maxMuonEta
            || abs(p1.Eta()) >= maxMuonEta)
            return {};
 
        return m0 + m1;
    }

Member Data Documentation

category

EventCategory category

The event category. This determines which other fields are valid.

dimuon

Di<const Muon, const Muon> dimuon

The dimuon system. Invalid for NotSelected events.

maxMuonEta

constexpr static double maxMuonEta = 2.4

static

Muon chamber acceptance.

maxPhotonEta

constexpr static double maxPhotonEta = 2.4

static

Muon chamber acceptance.

maxZMass

constexpr static double maxZMass = 106

static

mZ + 15 GeV

minMuMuMass

constexpr static double minMuMuMass = 40

static

Trigger efficiency.

minMuon0Pt

constexpr static double minMuon0Pt = 20

staticconstexpr

Scale factors start at 15 GeV.

minMuon1Pt

constexpr static double minMuon1Pt = 15

static

Dimuon trigger.

minPhotonPt

constexpr static double minPhotonPt = 20

static

Scale factors start at 20 GeV.

minZMass

constexpr static double minZMass = 76

static

mZ - 15 GeV

mMuMu

float mMuMu

The invariant mass of the dimuon system. Invalid for NotSelected events.

mMuMuGamma

float mMuMuGamma

Mass of the dimuon + photon system. Only valid for MuMuGamma events.

selectedPhotons

std::vector<Photon> selectedPhotons

Considered photons. Only valid for MuMuGamma events.

weight

float weight

Event weight. Always valid; for NotSelected events, this does not include the muons nor the photon weights.

Todo:

Correlation bit.

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The documentation for this struct was generated from the following file:

• /builds/cms-analysis/general/DasAnalysisSystem/Core/Installer/Core/Unfolding/interface/ZmmYCommon.h