Performance of online b tagging in proton-proton collisions at 13 TeV at the CMS experiment

CMS DP_2017-011

Online vs offline b-tagging performance (uds-quark) Performance of the online (red) and offline (blue) b jet identification efficiency demonstrating the probability for uds jets to be misidentified as b jet as a function of the efficiency to correctly identify b jets. Both online and offline b-tagging are performed using CSVv2 algorithm. The curves are obtained for the eight leading online and offline jets with pT> 30 GeV and abs(eta)<2.4 in simulated tt events, b jets from gluon splitting to a pair of b quarks are considered as b jets. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. The performance in this figure serves as an illustration since the b jet identification efficiency depends on the pT and eta distribution of the jets in the topology as well as the amount of b jets from gluon splitting in the sample. [Get pdf version] Contact: Silvio Donato

Online vs offline b-tagging performance (uds-quark)
Performance of the online (red) and offline (blue) b jet identification efficiency demonstrating the probability for uds jets to be misidentified as b jet as a function of the efficiency to correctly identify b jets. Both online and offline b-tagging are performed using CSVv2 algorithm. The curves are obtained for the eight leading online and offline jets with pT> 30 GeV and abs(eta)<2.4 in simulated tt events, b jets from gluon splitting to a pair of b quarks are considered as b jets. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. The performance in this figure serves as an illustration since the b jet identification efficiency depends on the pT and eta distribution of the jets in the topology as well as the amount of b jets from gluon splitting in the sample. [Get pdf version]
Contact: Silvio Donato

Online vs offline b-tagging performance (c-quark) Performance of the online (red) and offline (blue) b jet identification efficiency demonstrating the probability for c jets to be misidentified as b jet as a function of the efficiency to correctly identify b jets. Both online and offline b-tagging are performed using CSVv2 algorithm. The curves are obtained for the eight leading online and offline jets with pT> 30 GeV and abs(eta)<2.4 in simulated tt events, b jets from gluon splitting to a pair of b quarks are considered as b jets. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. The performance in this figure serves as an illustration since the b jet identification efficiency depends on the pT and eta distribution of the jets in the topology as well as the amount of b jets from gluon splitting in the sample. [Get pdf version] Contact: Silvio Donato

Online vs offline b-tagging performance (c-quark)
Performance of the online (red) and offline (blue) b jet identification efficiency demonstrating the probability for c jets to be misidentified as b jet as a function of the efficiency to correctly identify b jets. Both online and offline b-tagging are performed using CSVv2 algorithm. The curves are obtained for the eight leading online and offline jets with pT> 30 GeV and abs(eta)<2.4 in simulated tt events, b jets from gluon splitting to a pair of b quarks are considered as b jets. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. The performance in this figure serves as an illustration since the b jet identification efficiency depends on the pT and eta distribution of the jets in the topology as well as the amount of b jets from gluon splitting in the sample. [Get pdf version]
Contact: Silvio Donato

Online vertex resolution Online vertex resolution using the full tracker (red) and only the pixel tracker (blue). The plots are obtained using simulated multijet events generated with a flat pT parton distribution between 15 GeV and 3000 GeV. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. [Get pdf version] Contact: Silvio Donato

Online vertex resolution
Online vertex resolution using the full tracker (red) and only the pixel tracker (blue). The plots are obtained using simulated multijet events generated with a flat pT parton distribution between 15 GeV and 3000 GeV. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. [Get pdf version]
Contact: Silvio Donato

Fast primary vertex resolution Resolution of the fast primary vertex algorithm that finds the primary vertex projecting the pixel hits back to the beam line using the jets direction. The fast primary vertex algorithm is used as a first step of the online b tagging, in order to reconstruct only the tracks close to the primary vertex. In 2017, a z-depended bias correction will be applied in order to remove the two-peak feature of the plot. The plot is obtained using simulated multijet events generated with a leading jet pT distribution flat between 15 GeV and 3000 GeV. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. [Get pdf version] Contact: Silvio Donato

Fast primary vertex resolution
Resolution of the fast primary vertex algorithm that finds the primary vertex projecting the pixel hits back to the beam line using the jets direction. The fast primary vertex algorithm is used as a first step of the online b tagging, in order to reconstruct only the tracks close to the primary vertex. In 2017, a z-depended bias correction will be applied in order to remove the two-peak feature of the plot. The plot is obtained using simulated multijet events generated with a leading jet pT distribution flat between 15 GeV and 3000 GeV. The plot is obtained using the 2016 detector conditions with 35 pile-up collisions. Only events having a sum of online jet pT > 250 GeV are considered. [Get pdf version]
Contact: Silvio Donato

Online b-tagging computing time Processing time of the online regional tracking to b tag the leading eight jets with pT > 30 GeV (red) and of the online tracking for particle flow (blue). For reference, the limit on the average global time of the HLT farm is about 200 ms. The plot is obtained using 2016 data with an average pile-up of 49 and having a sum of online jet pT > 250 GeV. The online b tagging was run in ~6% of events accepted by L1 trigger. The number in the parentheses is the average processing time per event. Overflow events are shown in the last bin and are taken into account in the average processing time computation. [Get pdf version] Contact: Silvio Donato

Online b-tagging computing time
Processing time of the online regional tracking to b tag the leading eight jets with pT > 30 GeV (red) and of the online tracking for particle flow (blue). For reference, the limit on the average global time of the HLT farm is about 200 ms. The plot is obtained using 2016 data with an average pile-up of 49 and having a sum of online jet pT > 250 GeV. The online b tagging was run in ~6% of events accepted by L1 trigger. The number in the parentheses is the average processing time per event. Overflow events are shown in the last bin and are taken into account in the average processing time computation. [Get pdf version]
Contact: Silvio Donato

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
pdf	btagPaper.pdf	r1	manage	21.0 K	2017-05-04 - 09:21	ElisabettaGallo
png	btagPaper.png	r1	manage	31.8 K	2017-05-04 - 09:21	ElisabettaGallo
pdf	btagPaperFastPV.pdf	r1	manage	15.0 K	2017-05-04 - 09:21	ElisabettaGallo
png	btagPaperFastPV.png	r1	manage	27.0 K	2017-05-04 - 09:21	ElisabettaGallo
pdf	btaggingVsC.pdf	r1	manage	18.2 K	2017-05-04 - 09:21	ElisabettaGallo
png	btaggingVsC.png	r1	manage	22.3 K	2017-05-04 - 09:21	ElisabettaGallo
pdf	btaggingVsUds.pdf	r1	manage	18.3 K	2017-05-04 - 09:21	ElisabettaGallo
png	btaggingVsUds.png	r1	manage	23.4 K	2017-05-04 - 09:21	ElisabettaGallo
pdf	timing.pdf	r1	manage	16.8 K	2017-05-04 - 09:21	ElisabettaGallo
png	timing.png	r1	manage	28.3 K	2017-05-04 - 09:21	ElisabettaGallo

Topic revision: r2 - 2017-05-04 - ElisabettaGallo

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