Top quark pair events for heavy flavour tagging and vertexing at the LHC

This data contains jets from top anti-top decays. The event and parton shower are simulated in Pythia 8 with a centre of mass energy of 13 TeV, with detector response modelled in the Delphes framework. The detector response is modelled on the ATLAS detector, and a mean pileup of 50 was used. The dataset consists of jets, jet constituents, and truth heavy-flavour hadrons. For each jet, up to 50 charged constituents and 5 truth hadrons are included. Each constituent includes a link to the truth hadron associated, if such a link exists. Provided are 5 files, which are detailed below class_dict.yaml - Details the relative weights for classification labels, based on the frequency of occurrence for a given entry. Labels are detailed below. norm_dict.yaml - Contains the means and standard deviations of variables that can be used for training, allowing for scaling. pp_output_train.h5 - 13.5 million training jets, consisting of 4.5 million b-jets, c-jets, and light-flavoured jets. Resampling is applied over the jet pT and eta, to ensure equivalent kinematic distributions pp_output_val.h5 - 1.35 million jets for validation, consisting of 450,000 of each jet flavour. Kinematics are resampled in the same way as the training file. pp_output_test_ttbar.h5 - 1.35 million jets for evaluation, consisting of 450,000 of each jet flavour, with no kinematic resampling applied. Each h5 file contains the following groups: Jets - (N,) - N jets, including variables such as jet kinematics, flavours, and summary statistics on the number of hadrons and constituents in the jet. Consts (N,50) - Up to 50 charged constituents per jet. Includes details on constituent kinematics and identification. A variable 'valid' is True for tracks in the jet, and False for all other tracks. The additional variable 'truth_hadron_idx' details which hadron (if any) a constituent is associated to. Hadrons (N, 5) - Up to 5 truth heavy-flavour hadrons per jet. Each hadron includes details on kinematics. The variable 'hadron_idx' represents an ID for the hadron, and matches to the constituent variable 'truth_hadron_idx'. Each group contains both variables that can be used in training, and truth labels, which are as follows: Jets flavour - Flavour ID of the jet, 5 for b-jets (containing at least 1 b-hadron within a 0.4 dR(jet, hadron) match), 4 for c-jets (no b-hadrons, and contains at least 1 c-hadron), 0 for light-flavoured jets (contains no b- or c-hadrons) Consts truth_hadron_idx - integer that refers to hadron that produced the constituent. '-1' for padded tracks, or tracks with no truth heavy flavour hadron (e.g, pileup, hadronisation). truth_vertex_idx - integer that refers to the vertex a constituent came from - if two tracks have an equivalent truth_vertex_idx, they originate from the same vertex. Hadrons hadron_idx - The idx of the hadron, value is '-1' for padded hadrons, 0-4 for remaining hadrons. If a constituent 'truth_hadron_idx' matches with this value, then the constituent came from this heavy flavour hadron decay. flavour - The flavour of the hadron. '5' if the hadron contains at least 1 b-quark, '4' if there is no b-quark but a c-quark is present, '-1' for padded hadrons pt, lxy, dr, mass - The transverse momentum (pt) [GeV], transverse distance between hadronic decay vertex and the primary vertex (lxy) [mm], dR(Jet, Hadron), and the hadron truth mass [GeV] This dataset allows for studies into algorithms that aim to perform vertex reconstruction.本数据集包含顶反顶衰变产生的喷注。事件与部分子簇射（parton shower）采用Pythia 8（Pythia 8）进行模拟，质心系能量为13 TeV；探测器响应采用Delphes框架（Delphes）建模，其设计基于ATLAS探测器（ATLAS），并使用了平均50的叠加事件（pileup）水平。 数据集由喷注、喷注组成粒子以及真实重味强子构成。每个喷注最多包含50个带电组成粒子与5个真实强子。若某组成粒子存在关联的真实强子，则会附带对应的关联标识。 本次共提供5个数据文件，具体说明如下： 1. class_dict.yaml：分类标签相对权重文件，基于给定条目的出现频率生成，标签详情如下。 2. norm_dict.yaml：包含训练可用变量的均值与标准差，可用于数据的标准化缩放。 3. pp_output_train.h5：包含1350万个训练喷注，其中450万个为b喷注（b-jets）、c喷注（c-jets）与轻味喷注（light-flavoured jets）。针对喷注的横向动量（pt）与赝快度（η）进行了重采样，以保证运动学分布的一致性。 4. pp_output_val.h5：包含135万个验证喷注，每种喷注风味各45万个。重采样方式与训练文件完全一致。 5. pp_output_test_ttbar.h5：包含135万个评估用喷注，每种喷注风味各45万个，未进行运动学重采样。 每个h5文件均包含以下数据组： - Jets：维度为(N,)，代表N个喷注，包含喷注运动学参数、喷注风味以及喷注内强子与组成粒子数量的统计量等变量。 - Consts (N,50)：每个喷注最多包含50个带电组成粒子，包含组成粒子的运动学参数与识别信息。变量'valid'用于标识喷注内的径迹（值为True）与非喷注径迹（值为False）。额外变量'truth_hadron_idx'用于指示组成粒子所关联的真实强子（若存在）。 - Hadrons (N, 5)：每个喷注最多包含5个真实重味强子，每个强子包含运动学参数信息。变量'hadron_idx'为强子的唯一标识，与组成粒子变量'truth_hadron_idx'一一对应。 每个数据组均包含可用于训练的变量与真实标签，具体如下： ### Jets组 - flavour：喷注的风味标识，5代表b喷注（在0.4的dR(喷注, 强子)匹配半径内至少包含1个b强子），4代表c喷注（无b强子，但至少包含1个c强子），0代表轻味喷注（无b或c强子）。 ### Consts组 - truth_hadron_idx：指代产生该组成粒子的强子的整数标识，-1代表填充用径迹或无关联真实重味强子的径迹（例如叠加事件粒子、强子化产生的粒子）。 - truth_vertex_idx：指代组成粒子来源顶点的整数标识，若两条径迹的truth_vertex_idx相同，则二者源自同一顶点。 ### Hadrons组 - hadron_idx：强子的索引标识，-1代表填充用强子，0-4代表其余强子。若某组成粒子的'truth_hadron_idx'与该值匹配，则该组成粒子源自该重味强子的衰变。 - flavour：强子的风味标识，5代表该强子至少包含1个b夸克，4代表无b夸克但包含c夸克，-1代表填充用强子。 - pt、lxy、dr、mass：分别为横向动量（pt，单位GeV）、强子衰变顶点与初级顶点的横向距离（lxy，单位mm）、喷注与强子之间的dR值，以及强子的真实质量（单位GeV）。 本数据集可用于研究旨在实现顶点重建的算法。