Experiment-specific missing-ET smearing functions

Classes
struct	Rivet::METSmearParams
	Struct for holding MET-smearing parameters. More...

Typedefs
typedef function< METSmearParams(const Vector3 &, double)>	Rivet::METSmearParamsFn
typedef function< Vector3(const Vector3 &, double)>	Rivet::METSmearFn

Functions
METSmearParams	Rivet::MET_SMEARPARAMS_ATLAS_RUN1 (const Vector3 &met, double set)
	ATLAS Run 1 ETmiss resolution.
Vector3	Rivet::MET_SMEAR_ATLAS_RUN1 (const Vector3 &met, double set)
	ATLAS Run 1 ETmiss smearing.
METSmearParams	Rivet::MET_SMEARPARAMS_ATLAS_RUN2 (const Vector3 &met, double set)
Vector3	Rivet::MET_SMEAR_ATLAS_RUN2 (const Vector3 &met, double set)
	ATLAS Run 2 ETmiss smearing.
METSmearParams	Rivet::MET_SMEARPARAMS_CMS_RUN1 (const Vector3 &met, double set)
Vector3	Rivet::MET_SMEAR_CMS_RUN1 (const Vector3 &met, double set)
	CMS Run 1 ETmiss smearing.
METSmearParams	Rivet::MET_SMEARPARAMS_CMS_RUN2 (const Vector3 &met, double set)
	CMS Run 2 ETmiss smearing.
Vector3	Rivet::MET_SMEAR_CMS_RUN2 (const Vector3 &met, double set)
	CMS Run 2 ETmiss smearing.
Vector3	Rivet::MET_SMEAR_NORM (const METSmearParams &msps)
	Smear a nominal vector magnitude by Gaussian with the given absolute resolutions.
METSmearParams	Rivet::MET_SMEARPARAMS_IDENTITY (const Vector3 &met, double)
	Identity resolution is 0 (perfect delta function, no offset)
Vector3	Rivet::MET_SMEAR_IDENTITY (const Vector3 &met, double)
	Identity MET smearing just returns the input.

Detailed Description

Typedef Documentation

METSmearFn

typedef function<Vector3(const Vector3&, double)> Rivet::METSmearFn

Typedef for MET smearing functions/functors (given a MET vector and scalar sum(ET))

Todo:

Allow MET calculation to access the whole Event?

METSmearParamsFn

typedef function<METSmearParams(const Vector3&, double)> Rivet::METSmearParamsFn

Typedef for MET smearing-parameter functions/functors (given a MET vector and scalar sum(ET))

Returns a nominal MET 3-vector (maybe shifted in energy or angle) and a resolution (in GeV) with which to Gaussian-smear its momentum.

Todo:

Allow MET calculation to access the whole Event?

Function Documentation

MET_SMEAR_NORM()

Vector3 Rivet::MET_SMEAR_NORM ( const METSmearParams &  msps )

inline

Smear a nominal vector magnitude by Gaussian with the given absolute resolutions.

Note

For momentum resolutions comparable to or larger than the value they are smearing, a modulus of the resulting vaue is taken, i.e. "reflecting" negative tails back up to positive rather than truncating at zero (or – horrors – accidentally flipping the vector direction!) This is not obviously better than truncating at zero, and ideally we'd avoid this with some physical positive-definite sampling... but until then let's try to make sure the assuming-Gaussian resolution functions don't have to work in very asymmetric regimes where a single sigma isn't enough.

Todo:

Improve on "reflect in zero" sampling behaviour where res >~ mu.

References Rivet::Vector< N >::mod(), Rivet::randnorm(), and Rivet::Vector3::unit().

Referenced by Rivet::MET_SMEAR_ATLAS_RUN1(), Rivet::MET_SMEAR_ATLAS_RUN2(), Rivet::MET_SMEAR_CMS_RUN1(), Rivet::MET_SMEAR_CMS_RUN2(), and Rivet::SmearedMET::project().

MET_SMEARPARAMS_ATLAS_RUN1()

METSmearParams Rivet::MET_SMEARPARAMS_ATLAS_RUN1 ( const Vector3 &  met, double  set  )

inline

ATLAS Run 1 ETmiss resolution.

Based on https://arxiv.org/pdf/1108.5602v2.pdf, Figs 14 and 15

References Rivet::Vector< N >::mod().

Referenced by Rivet::MET_SMEAR_ATLAS_RUN1().

MET_SMEARPARAMS_ATLAS_RUN2()

METSmearParams Rivet::MET_SMEARPARAMS_ATLAS_RUN2 ( const Vector3 &  met, double  set  )

inline

ATLAS Run 2 ETmiss resolution

Based on https://arxiv.org/pdf/1802.08168.pdf, Figs 6-9

Todo:

Allow smearing function to access the whole event, since Njet also affects? Or assume encoded in SET?

Todo:

Arguably should somehow take the max of this and the linearity... but this is re-used

References Rivet::max(), Rivet::min(), and Rivet::Vector< N >::mod().

Referenced by Rivet::MET_SMEAR_ATLAS_RUN2().

MET_SMEARPARAMS_CMS_RUN1()

METSmearParams Rivet::MET_SMEARPARAMS_CMS_RUN1 ( const Vector3 &  met, double  set  )

inline

CMS Run 1 ETmiss smearing params

From https://arxiv.org/pdf/1411.0511.pdf Table 2, p16 (Z channels)

References Rivet::sqr().

Referenced by Rivet::MET_SMEAR_CMS_RUN1().

MET_SMEARPARAMS_CMS_RUN2()

METSmearParams Rivet::MET_SMEARPARAMS_CMS_RUN2 ( const Vector3 &  met, double  set  )

inline

CMS Run 2 ETmiss smearing.

From http://inspirehep.net/record/1681214/files/JME-17-001-pas.pdf Table 3, p20

References Rivet::sqr().

Referenced by Rivet::MET_SMEAR_CMS_RUN2().

MET_SMEARPARAMS_IDENTITY()

METSmearParams Rivet::MET_SMEARPARAMS_IDENTITY ( const Vector3 &  met, double    )

inline

Identity resolution is 0 (perfect delta function, no offset)

Note

This simple factorization doesn't allow for expression of offsets or angular smearing... revisit if needed