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| CMS-PAS-SMP-20-010 | ||
| Study of quark and gluon jet substructure in dijet and Z+jet events from $\text{p}\text{p}$ collisions | ||
| CMS Collaboration | ||
| March 2021 | ||
| Abstract: A measurement of jet substructure observables describing the distribution of particles within quark- and gluon-initiated jets is presented in this note. Proton-proton collision data at $\sqrt{s}= $ 13 TeV collected by the CMS detector are used, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. A set of generalized angularities with varying sensitivity to the distributions of transverse momenta and angular distances within a jet are studied. The analysis is carried out using a dijet event sample enriched in gluon-initiated jets, and, for the first time, also a Z+jet event sample enriched in quark-initiated jets. The measurement is carried out in bins of jet transverse momentum, and as a function of jet size parameter, for multiple observables with and without a jet grooming procedure applied. Using these measurements, the ability of various models to describe jet substructure observables is studied, showing the clear need for improvements in Monte Carlo generators. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, Submitted to JHEP. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Fraction of AK4 gluon jets in the Z+jet region (red triangles), and the central (black circles) and forward (blue squares) jets in the dijet region. |
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Figure 2:
Data to simulation comparisons of the jet ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet (right) regions. The error bars correspond to the statistical uncertainties of the experimental data. The darker hashed region in each ratio plot indicates the statistical uncertainty in the experimental data, whilst the lighter hashed region represents the total uncertainty in the MC prediction. This includes all experimental, physics modelling, scale, and PDF uncertainties described in Section 6. |
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Figure 2-a:
Data to simulation comparisons of the jet ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet (right) regions. The error bars correspond to the statistical uncertainties of the experimental data. The darker hashed region in each ratio plot indicates the statistical uncertainty in the experimental data, whilst the lighter hashed region represents the total uncertainty in the MC prediction. This includes all experimental, physics modelling, scale, and PDF uncertainties described in Section 6. |
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Figure 2-b:
Data to simulation comparisons of the jet ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet (right) regions. The error bars correspond to the statistical uncertainties of the experimental data. The darker hashed region in each ratio plot indicates the statistical uncertainty in the experimental data, whilst the lighter hashed region represents the total uncertainty in the MC prediction. This includes all experimental, physics modelling, scale, and PDF uncertainties described in Section 6. |
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Figure 3:
The five generalized angularities ${\lambda ^{\kappa}_{\beta}}$ used in this analysis, represented in the $(\kappa, \beta)$ plane. The Les Houches Angularity is denoted by LHA. Adapted from [44]. |
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Figure 4:
Detector-level and particle-level (unfolded) experimental data distributions of LHA (${\lambda ^{1}_{0.5}}$) (left) using charged+neutral constituents, and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$) (right) using only charged constituents, for jets with 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet (red) and central dijet (black) regions. The detector-level data uncertainties are purely statistical. The particle-level (unfolded) data uncertainties include systematic uncertainties. Also shown is the mean of each distribution, calculated from the binned distribution. The ratio plots show the ratio of dijet to Z+jet distributions, for both the detector- and particle-level distributions. |
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Figure 4-a:
Detector-level and particle-level (unfolded) experimental data distributions of LHA (${\lambda ^{1}_{0.5}}$) (left) using charged+neutral constituents, and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$) (right) using only charged constituents, for jets with 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet (red) and central dijet (black) regions. The detector-level data uncertainties are purely statistical. The particle-level (unfolded) data uncertainties include systematic uncertainties. Also shown is the mean of each distribution, calculated from the binned distribution. The ratio plots show the ratio of dijet to Z+jet distributions, for both the detector- and particle-level distributions. |
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Figure 4-b:
Detector-level and particle-level (unfolded) experimental data distributions of LHA (${\lambda ^{1}_{0.5}}$) (left) using charged+neutral constituents, and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$) (right) using only charged constituents, for jets with 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet (red) and central dijet (black) regions. The detector-level data uncertainties are purely statistical. The particle-level (unfolded) data uncertainties include systematic uncertainties. Also shown is the mean of each distribution, calculated from the binned distribution. The ratio plots show the ratio of dijet to Z+jet distributions, for both the detector- and particle-level distributions. |
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Figure 5:
Ratio of the shifted distribution to the nominal distribution of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets with 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the central dijet region before (left) and after (right) normalization. The darker hashed region indicates the statistical uncertainty of the experimental data, whilst the lighter hashed region represents the total uncertainty. The total uncertainty represents the sum in quadrature of statistical and systematic uncertainties. The single-sided uncertainty for shower and hadronization is estimated from {herwig++} and is symmetrized for display in the total systematic uncertainty. |
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Figure 5-a:
Ratio of the shifted distribution to the nominal distribution of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets with 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the central dijet region before (left) and after (right) normalization. The darker hashed region indicates the statistical uncertainty of the experimental data, whilst the lighter hashed region represents the total uncertainty. The total uncertainty represents the sum in quadrature of statistical and systematic uncertainties. The single-sided uncertainty for shower and hadronization is estimated from {herwig++} and is symmetrized for display in the total systematic uncertainty. |
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Figure 5-b:
Ratio of the shifted distribution to the nominal distribution of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets with 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the central dijet region before (left) and after (right) normalization. The darker hashed region indicates the statistical uncertainty of the experimental data, whilst the lighter hashed region represents the total uncertainty. The total uncertainty represents the sum in quadrature of statistical and systematic uncertainties. The single-sided uncertainty for shower and hadronization is estimated from {herwig++} and is symmetrized for display in the total systematic uncertainty. |
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Figure 6:
Particle-level distributions of ungroomed LHA (${\lambda ^{1}_{0.5}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 6-a:
Particle-level distributions of ungroomed LHA (${\lambda ^{1}_{0.5}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 6-b:
Particle-level distributions of ungroomed LHA (${\lambda ^{1}_{0.5}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 7:
Particle-level distributions of ungroomed width (${\lambda ^{1}_{1}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 7-a:
Particle-level distributions of ungroomed width (${\lambda ^{1}_{1}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 7-b:
Particle-level distributions of ungroomed width (${\lambda ^{1}_{1}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 8:
Particle-level distributions of ungroomed thrust (${\lambda ^{1}_{2}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 8-a:
Particle-level distributions of ungroomed thrust (${\lambda ^{1}_{2}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 8-b:
Particle-level distributions of ungroomed thrust (${\lambda ^{1}_{2}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 9:
Particle-level distributions of ungroomed multiplicity (${\lambda ^{0}_{0}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 9-a:
Particle-level distributions of ungroomed multiplicity (${\lambda ^{0}_{0}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 9-b:
Particle-level distributions of ungroomed multiplicity (${\lambda ^{0}_{0}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 10:
Particle-level distributions of ungroomed ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 10-a:
Particle-level distributions of ungroomed ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 10-b:
Particle-level distributions of ungroomed ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$) in 120 $ < {p_{\mathrm {T}}} < $ 150 GeV in the Z+jet region (left) and central dijet region (right). The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 11:
Particle-level distributions of variants of LHA (${\lambda ^{1}_{0.5}}$) in the central dijet region: (upper left) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (upper right) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower left) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower right) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV. The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 11-a:
Particle-level distributions of variants of LHA (${\lambda ^{1}_{0.5}}$) in the central dijet region: (upper left) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (upper right) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower left) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower right) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV. The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 11-b:
Particle-level distributions of variants of LHA (${\lambda ^{1}_{0.5}}$) in the central dijet region: (upper left) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (upper right) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower left) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower right) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV. The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 11-c:
Particle-level distributions of variants of LHA (${\lambda ^{1}_{0.5}}$) in the central dijet region: (upper left) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (upper right) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower left) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower right) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV. The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 11-d:
Particle-level distributions of variants of LHA (${\lambda ^{1}_{0.5}}$) in the central dijet region: (upper left) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (upper right) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower left) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (lower right) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV. The light blue and black error bars correspond to the statistical and total uncertainties of the experimental data, respectively. |
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Figure 12:
Mean of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets as a function of ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet region (right) regions. The error bars on the data and the hashed region in the ratio plot correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 12-a:
Mean of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets as a function of ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet region (right) regions. The error bars on the data and the hashed region in the ratio plot correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 12-b:
Mean of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets as a function of ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet region (right) regions. The error bars on the data and the hashed region in the ratio plot correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 12-c:
Mean of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets as a function of ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet region (right) regions. The error bars on the data and the hashed region in the ratio plot correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 12-d:
Mean of ungroomed LHA (${\lambda ^{1}_{0.5}}$) for AK4 jets as a function of ${p_{\mathrm {T}}}$ in the Z+jet (left) and central dijet region (right) regions. The error bars on the data and the hashed region in the ratio plot correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 13:
Mean of substructure observables in regions with gluon-enriched and quark-enriched jets, for the following configurations: (1) ungroomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (2) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (3) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (4) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and (5) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV; shown for each of the observables LHA (${\lambda ^{1}_{0.5}}$), width (${\lambda ^{1}_{1}}$), thrust (${\lambda ^{1}_{2}}$), multiplicity (${\lambda ^{0}_{0}}$), and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$). The central jet in the dijet region is used for the gluon-enriched sample, whilst for the quark-enriched sample the jet in the Z+jet region is used for 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and the forward jet in the dijet region is used for 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV. The error bars on the data correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 13-a:
Mean of substructure observables in regions with gluon-enriched and quark-enriched jets, for the following configurations: (1) ungroomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (2) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (3) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (4) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and (5) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV; shown for each of the observables LHA (${\lambda ^{1}_{0.5}}$), width (${\lambda ^{1}_{1}}$), thrust (${\lambda ^{1}_{2}}$), multiplicity (${\lambda ^{0}_{0}}$), and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$). The central jet in the dijet region is used for the gluon-enriched sample, whilst for the quark-enriched sample the jet in the Z+jet region is used for 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and the forward jet in the dijet region is used for 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV. The error bars on the data correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 13-b:
Mean of substructure observables in regions with gluon-enriched and quark-enriched jets, for the following configurations: (1) ungroomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (2) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (3) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (4) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and (5) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV; shown for each of the observables LHA (${\lambda ^{1}_{0.5}}$), width (${\lambda ^{1}_{1}}$), thrust (${\lambda ^{1}_{2}}$), multiplicity (${\lambda ^{0}_{0}}$), and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$). The central jet in the dijet region is used for the gluon-enriched sample, whilst for the quark-enriched sample the jet in the Z+jet region is used for 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and the forward jet in the dijet region is used for 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV. The error bars on the data correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 14:
Ratio of the mean of substructure observables in regions with gluon-enriched and quark-enriched jets, for the following configurations: (1) ungroomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (2) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (3) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (4) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and (5) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV; for the observables LHA (${\lambda ^{1}_{0.5}}$), width (${\lambda ^{1}_{1}}$), thrust (${\lambda ^{1}_{2}}$), multiplicity (${\lambda ^{0}_{0}}$), and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$). The central jet in the dijet region is used for the gluon-enriched sample, whilst for the quark-enriched sample the jet in the Z+jet region is used for 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and the forward jet in the dijet region is used for 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV. The error bars on the data correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 14-a:
Ratio of the mean of substructure observables in regions with gluon-enriched and quark-enriched jets, for the following configurations: (1) ungroomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (2) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (3) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (4) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and (5) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV; for the observables LHA (${\lambda ^{1}_{0.5}}$), width (${\lambda ^{1}_{1}}$), thrust (${\lambda ^{1}_{2}}$), multiplicity (${\lambda ^{0}_{0}}$), and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$). The central jet in the dijet region is used for the gluon-enriched sample, whilst for the quark-enriched sample the jet in the Z+jet region is used for 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and the forward jet in the dijet region is used for 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV. The error bars on the data correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
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Figure 14-b:
Ratio of the mean of substructure observables in regions with gluon-enriched and quark-enriched jets, for the following configurations: (1) ungroomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (2) ungroomed AK4 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV, (3) ungroomed AK8 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, (4) ungroomed charged-only AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and (5) groomed AK4 120 $ < {p_{\mathrm {T}}} < $ 150 GeV; for the observables LHA (${\lambda ^{1}_{0.5}}$), width (${\lambda ^{1}_{1}}$), thrust (${\lambda ^{1}_{2}}$), multiplicity (${\lambda ^{0}_{0}}$), and ${(p_{\mathrm {T}}^{D})^2}$ (${\lambda ^{2}_{0}}$). The central jet in the dijet region is used for the gluon-enriched sample, whilst for the quark-enriched sample the jet in the Z+jet region is used for 120 $ < {p_{\mathrm {T}}} < $ 150 GeV, and the forward jet in the dijet region is used for 1000 $ < {p_{\mathrm {T}}} < $ 4000 GeV. The error bars on the data correspond to the total uncertainties of the experimental data. The error bars on the simulation correspond to the statistical uncertainties of the simulation. |
| Tables | |
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Table 1:
Summary of zero bias and jet triggers used in the analysis for the dijet region. For each trigger, the integrated luminosity and number of events collected by it are given. The offline ${p_{\mathrm {T}}}$ bin threshold(s) indicate the lower edge of the ${p_{\mathrm {T}}}$ bin(s) measured with data from a given trigger. |
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Table 2:
Summary of the selection criteria for the Z+jet and dijet event samples. |
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Table 3:
Summary of the variants of observables measured in this note. |
| Summary |
| Measurements of distributions of generalized jet angularities in pp collision data taken at $\sqrt{s} = $ 13 TeV in dijet and for the first time also in Z+jet topologies have been presented. While the dijet topology allows access to a sample of jets that predominantly originate from gluon fragmentation, the Z+jet topology yields a sample enriched in quark-initiated jets. A set of five generalized angularities is measured to study different features in the modelling of jet substructure observables. Three infrared and collinear-safe angularities are particularly sensitive to the modelling of perturbative emissions in jets, while the other two have larger contributions from non-perturbative effects. For the first time, a study of angularities with different jet radii, both with and without the application of a grooming algorithm, was carried out to further discriminate between different features in the modelling. It was found that the measurements for quark and gluon jets yield values in between the predictions from the MG 5+PYTHIA 8 and HERWIG++ simulations. The quality of modelling for the infrared and collinear-safe angularities is found to be sensitive to the quark and gluon composition of the sample of jets. It is also found to be largely independent of whether a grooming algorithm is applied, suggesting that the quality depends mainly on the perturbative emissions in jets, rather than non-perturbative effects. A comparison of the means of the angularities in quark- and gluon-enriched data samples demonstrated their discrimination power, which was found to be overestimated by all generators under study, showing the clear need for improvements in the MC. In outlook, this measurement will allow a detailed analysis of the assumptions and approximations made in calculations and Monte Carlo simulations of jet substructure, ideally yielding better predictions for experimental searches and measurements that rely on jet substructure. |
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