Dataset for flavour tagging R&D

This is a dataset for flavour tagging R&D.

It consists of b-jets, c-jets and light-jets in equal number and equal distributions of transverse momentum, pseudo-rapidity and track multiplicity. 

The jets are sampled from ttbar events produced from proton-proton collisions at 14 TeV, using Pythia8. An ATLAS-like detector is parameterized using Delphes. The anti-kT R=0.4 algorithm with calorimeter inputs is used to define the jets.

Jets are labelled as b-jets if there is a b-hadron within dR<0.3 of the jet, otherwise as c-jets if there is a c-hadron within dR<0.3, otherwise as light-jets. 

Tracks are associated to jets if they are within dR<0.4. If this condition holds for more than one jet, only the closest one is considered. Tracks are represented by their perigee parameters (d0, z0, pt, phi, cotan(theta)), which are smeared according to track pt and track eta dependent uncertainties.

This dataset is heavily based on the Secondary Vertex Finding in Jets Dataset and we thank J. Shlomi for the code and input.

本数据集面向味标记（flavour tagging）研发工作。
数据集包含等量的b喷注、c喷注与轻喷注，且三者在横向动量、赝快度及径迹多重数的分布完全一致。
喷注样本取自14 TeV质子-质子碰撞产生的顶夸克-反顶夸克（ttbar）事件，模拟采用Pythia8工具包。通过Delphes参数化构建类ATLAS探测器，并使用基于量能器输入的反kT（anti-kT）R=0.4算法定义喷注。
若某喷注的dR<0.3范围内存在b强子，则将其标记为b喷注；若不存在b强子但dR<0.3范围内存在c强子，则标记为c喷注；否则标记为轻喷注。
若径迹与喷注的dR<0.4，则将该径迹与喷注关联；若某径迹满足该条件的喷注不止一个，则仅选取距离最近的喷注进行关联。径迹以其近地点参数（perigee parameters）(d0, z0, pt, phi, cotan(theta))表示，参数的弥散程度根据径迹横向动量与赝快度相关的不确定度进行设定。
本数据集大量基于《喷注次级顶点寻找数据集》（Secondary Vertex Finding in Jets Dataset），在此感谢J. Shlomi提供的代码与输入数据。