13 TeV 2025 Data — Beta

In 2025 a updated and increased set of proton-proton (pp) collision data was released by the ATLAS Collaboration to the public for educational purposes. The data has been collected by the ATLAS detector at the LHC at 13 TeV during the year 2015 and 2016 and corresponds to an integrated luminosity of 36 fb^-1. The pp collision data is accompanied by a set of MC simulated samples describing several processes which are used to model the expected distributions of different signal and background events.

The released samples are provided in a simplified data format, reducing the information content of the data released as open data for research in 2024.

The resulting format is a ROOT tuple with about 80 branches (variables/features). For those not familiar with this modular scientific software toolkit, please refer to the ROOT documentation, which provides a rich set of tutorials and code examples.

Several final-state collections are provided within this release specifically tailored towards the example notebooks provided here. The selections applied to select events and the corresponding name of each collection are shown below:

Selection	Collection Name
At least one lepton with at least $7~$GeV of $p_{T}$ and $30~$GeV of missing transverse momentum (i.e. a leptonically-decaying W-boson enhanced selection)	1LMET30
Two to four leptons with at least $7~$GeV of $p_{T}$ each	2to4lep
At least two muons with at least $10~$GeV of $p_{T}$ (i.e. a leptonically-decaying Z-boson enhanced selection)	2muons
At least three jets with at least $20~$GeV of $p_{T}$, at least one lepton passing tight identification requirements with at least $7~$GeV of $p_{T}$, and $30~$GeV of missing transverse momentum (i.e. a semi-leptonic top-quark enhanced selection)	3J1LMET30
At least two photons with at least $25~$GeV of $p_{T}$ each (i.e. a Higgs boson decaying to two photons enhanced selection)	GamGam
At least two jets with at least $20~$GeV of $p_{T}$, at least two leptons passing tight identification requirements with at least $7~$GeV of $p_{T}$, and $30~$GeV of missing transverse momentum (i.e. a di-leptonic top-quark enhanced selection)	2J2LMET30
At least two jets with at least $20~$GeV of $p_{T}$ identified as containing at least one heavy flavor hadron using the $85\%$ working point (i.e. a Higgs boson decaying to b-quarks enhanced selection)	2bjets
At least three leptons with at least $7~$GeV of $p_{T}$ each	3lep
Exactly three leptons with at least $7~$GeV of $p_{T}$ (i.e. a leptonically-decaying W+Z boson enhanced selection)	exactly3lep
At least four leptons with at least $7~$GeV of $p_{T}$ each	4lep
Exactly four leptons with at least $7~$GeV of $p_{T}$ (i.e. a leptonically-decaying ZZ boson or Higgs to four leptons enhanced selection)	exactly4lep

Reconstructed physics objects

Several reconstructed physics objects (electrons, muons, photons, tau-leptons, small-R jets, large-R jets) are contained within the 13 TeV ATLAS Open Data, and their preselection requirements are detailed below:

Electron (e)	Muon ($\mu$)	Photon ($\gamma$)
InDet & EMCAL rec.	InDet & MS rec.	InDet & EMCAL rec.
$p_T > 7$ GeV	$p_T > 7$ GeV	$E_T > 25$ GeV
$\|\eta\|< 2.47$	$\|\eta\| < 2.5$	$\|\eta\| < 2.37$

$\tau$-leptons	Small-R jets	Large-R jets
InDet & EMCAL rec.	EMCAL & HCAL rec.	EMCAL & HCAL rec.
$p_T > 20$ GeV	anti-kt, R = 0.4	anti-kt, R = 1.0
$\|\eta\| < 2.5$	$p_T > 20$ GeV	$p_T > 250$ GeV
	$\|\eta\| < 2.5$	$\|\eta\| < 2.0$
	b-tagging (DL1dv01)	trimming: $R_{sub} = 0.2$, $f_{cut} = 0.05$

Variable list

The full list of ROOT branches (variables/features) contained within in this dataset is presented in the list below:

Variable Name	C++ type	Description
runNumber	unsigned int	run identifier
eventNumber	unsigned long long	event identifier
channelNumber	unsigned int	simulated data dataset ID e.g. $gg \rightarrow H \rightarrow ZZ^* \rightarrow e^+e^-e^+e^-$ is 345060
mcWeight	float	weight of a simulated event
filteff	float	efficiency of simulated process, e.g. if Higgs is forced to decay into two tau leptons in the simulated sample the filter efficiency reflects this
kfac	float	corrections to the cross section due to higher order calculations
xsec	float	the cross section in picobarn of the simulated process
ScaleFactor_PILEUP	float	scalefactor for pileup reweighting
ScaleFactor_ELE	float	scalefactor for electron efficiency
ScaleFactor_MUON	float	scalefactor for muon efficiency
ScaleFactor_PHOTON	float	scalefactor for photon efficiency
ScaleFactor_TAU	float	scalefactor for tau efficiency
ScaleFactor_BTAG	float	scalefactor for b-tagging algorithm using continous working point
ScaleFactor_LepTRIGGER	float	scalefactor for different operating efficiencies of used lepton triggers
ScaleFactor_TauTRIGGER	float	scalefactor for different operating efficiencies of used tau triggers
ScaleFactor_DiTauTRIGGER	float	scalefactor for different operating efficiencies of used ditau triggers
ScaleFactor_ElTRIGGER	Float_t	scalefactor for different operating efficiencies of used single electron triggers
ScaleFactor_FTAG	Float_t	scalefactor for b-tagging algorithm using continous working point
ScaleFactor_JVT	Float_t	scalefactor for jet vertex tagger (JVT) algorithm using the neural net (NN) working point
ScaleFactor_MLTRIGGER	Float_t	scalefactor for different operating efficiencies of used multilepton triggers
ScaleFactor_MuTRIGGER	Float_t	scalefactor for different operating efficiencies of used single muon triggers
TriggerMatch_DILEPTON	Float_t	scalefactor for different operating efficiencies of used di-lepton triggers
trigDE	bool	boolean whether the event has been selected by any of the di-electron triggers
trigDM	bool	boolean whether the event has been selected by any of the di-muon triggers
trigMET	bool	boolean whether the event has been selected by any of the missing transverse energy triggers
trigML	bool	boolean whether the event has been selected by any of the multi-lepton triggers
trigE	bool	boolean whether the event has been selected by any of the single electron triggers
trigM	bool	boolean whether the event has been selected by any of the single muon triggers
trigP	bool	boolean whether the event has been selected by any of the single photon triggers
trigT	bool	boolean whether the event has been selected by any of the single tau triggers
trigDT	bool	boolean whether the event has been selected by any of the di-tau triggers
lep_n	int	number of preselected leptons
lep_isTrigMatched	vector<bool>	boolean signifying whether the lepton is triggering the event
lep_pt	vector<float>	transverse momentum of the lepton
lep_eta	vector<float>	pseudo-rapidity of the lepton
lep_phi	vector<float>	azimuthal angle of the lepton
lep_e	vector<float>	energy of the lepton
lep_z0	vector<float>	z-coordinate of the track associated to the lepton wrt. primary vertex
lep_d0	vector<float>	transverse coordinate (in the xy-plane) of the track associated to the lepton wrt. primary vertex
lep_d0sig	vector<float>	$d_0$ divided by the uncertainty of the $d_0$ measurement
lep_charge	vector<int>	charge of the lepton
lep_type	vector<int>	number signifying the lepton type (e (11) or mu (13))
lep_isLooseID	vector<bool>	boolean indicating whether lepton satisfies loose ID reconstruction criteria
lep_isMediumID	vector<bool>	boolean indicating whether lepton satisfies medium ID reconstruction criteria
lep_isTightID	vector<bool>	boolean indicating whether lepton satisfies tight ID reconstruction criteria
lep_isLooseIso	vector<bool>	boolean indicating whether lepton satisfies loose isolation criteria
lep_isTightIso	vector<bool>	boolean indicating whether lepton satisfies tight isolation criteria
lep_ptvarcone30	vector<float>	scalar sum of track $p_T$ in a variable sized cone with $\Delta R_{max}=0.3$ around the lepton
lep_topoetcone20	vector<float>	scalar sum of calorimeter $E_T$ in a cone of $\Delta R=0.2$ around lepton
tau_n	int	number of preselected tau leptons
tau_pt	vector<float>	transverse momentum of the tau lepton
tau_eta	vector<float>	pseudo-rapidity of the tau lepton
tau_phi	vector<float>	azimuthal angle of the tau lepton
tau_e	vector<float>	energy of the tau lepton
tau_charge	vector<int>	charge of the tau lepton
tau_isTight	vector<bool>	boolean indicating whether tau lepton satisfies tight ID reconstruction criteria
tau_nTracks	vector<int>	number of core tracks for reconstructed tau lepton (either 1 or 3)
tau_RNNEleScore	vector<float>	RNN electron score to identify leptonically decaying taus
tau_RNNJetScore	vector<float>	RNN jet score to identify hadronically decaying taus
photon_n	int	number of preselected photons
photon_pt	vector<float>	transverse momentum of the photon
photon_eta	vector<float>	pseudo-rapidity of the photon
photon_phi	vector<float>	azimuthal angle of the photon
photon_e	vector<float>	energy of the photon
photon_ptcone20	vector<float>	scalar sum of track $p_T$ in a cone of R=0.2 around photon
photon_topoetcone40	vector<float>	scalar sum of track $E_T$ in a cone of R=0.4 around photon
photon_isLooseID	vector<bool>	boolean indicating whether photon satisfies loose ID reconstruction criteria
photon_isTightID	vector<bool>	boolean indicating whether photon satisfies tight ID reconstruction criteria
photon_isLooseIso	vector<bool>	boolean indicating whether photon satisfies loose isolation criteria
photon_isTightIso	vector<bool>	boolean indicating whether photon satisfies tight isolation criteria
met	float	transverse energy of the missing momentum vector
met_phi	float	azimuthal angle of the missing momentum vector
met_mpx	float	x-component of the missing momentum vector
met_mpy	float	y-component of the missing momentum vector
jet_n	int	number of preselected jets
jet_pt	vector<float>	transverse momentum of the jet
jet_eta	vector<float>	pseudo-rapidity of the jet
jet_phi	vector<float>	azimuthal angle of the jet
jet_e	vector<float>	energy of the jet
jet_jvt	vector<float>	jet vertex tagging of the jet
jet_btag_quantile	vector<int>	the quantile of the continous working point of the DL1dv0 b-jet tagger
jet_pt_jer1	vector<float>	transverse momentum of the jet after applying a specific systematic uncertainty from the jet energy resolution calibration
jet_pt_jer2	vector<float>	transverse momentum of the jet after applying a specific systematic uncertainty from the jet energy resolution calibration
largeRJet_n	int	number of preselected jets
largeRJet_pt	vector<float>	transverse momentum of the large radius jet
largeRJet_eta	vector<float>	pseudo-rapidity of the large radius jet
largeRJet_phi	vector<float>	azimuthal angle of the large radius jet
largeRJet_e	vector<float>	energy of the large radius jet
largeRJet_m	vector<float>	mass of the large radius jet
largeRJet_D2	vector<float>	variable to identify jets from hadronic Z-boson decays (JHEP12(2014)009)
truth_elec_eta	vector<float>	pseudo-rapidity of the truth electrons
truth_elec_n	Int_t	number of truth electrons
truth_elec_phi	vector<float>	azimuthal angle of the truth electrons
truth_elec_pt	vector<float>	transverse momentum of the truth electrons
truth_jet_eta	vector<float>	pseudo-rapidity of the truth jets
truth_jet_m	vector<float>	mass of the truth jets
truth_jet_n	Int_t	number of truth jets
truth_jet_phi	vector<float>	azimuthal angle of the truth jets
truth_jet_pt	vector<float>	transverse momentum of the truth jets
truth_met	Float_t	truth missing transverse energy
truth_met_phi	Float_t	azimuthal angle of the truth missing transverse energy
truth_muon_eta	vector<float>	pseudo-rapidity of the truth muon
truth_muon_n	Int_t	number of truth muons
truth_muon_phi	vector<float>	azimuthal angle of the truth muons
truth_muon_pt	vector<float>	transverse momentum of the truth muons
truth_photon_eta	vector<float>	pseudo-rapidity of the truth photons
truth_photon_n	Int_t	number of truth photons
truth_photon_phi	vector<float>	azimuthal angle of the truth photons
truth_photon_pt	vector<float>	transverse momentum of the truth photons
truth_tau_eta	vector<float>	pseudo-rapidity of the truth taus
truth_tau_n	Int_t	number of truth taus
truth_tau_phi	vector<float>	azimuthal angle of the truth taus
truth_tau_pt	vector<float>	transverse momentum of the truth taus