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| CMS-PAS-SMP-15-003 | ||
| Measurement of jet charge observables in dijet events at $\sqrt{s}=$ 8 TeV | ||
| CMS Collaboration | ||
| June 2016 | ||
| Abstract: Jet charge is an estimator for the electric charge of a quark, antiquark or gluon initiating a jet. It is based on the momentum-weighted sum of the measured electric charges of the jet constituents. A measurement of three different charge observables of the leading jet is performed in dijet events. The analysis is carried out with a data sample of 19.7 fb$^{-1}$ collected in proton-proton collisions at $\sqrt{s}=$ 8 TeV. The results are presented differentially in transverse momentum of the leading jet and compared to predictions from QCD-inspired leading order event generators. This is the first CMS measurement of jet charge observables unfolded for detector effects. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 10 (2017) 131. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Leading jet ${p_{\mathrm {T}}}$ distribution in data compared to PYTHIA 6 simulation. The fraction of events where the leading jet is matched to a generator quark or gluon are indicated as filled histograms. The ``others'' category represents those jets which are initiated by parton flavors including the anti-up quark ($\mathrm{ \bar{u} } $), the anti-down quark ($\mathrm{ \bar{d} } $), the charm, strange and bottom quarks ($\mathrm{c} $, $\mathrm{ \bar{c} } $, $\mathrm{ s } $, $\mathrm{ \bar{s} } $, $\mathrm{ b } $, $\mathrm{ \bar{b} } $) and the unmatched jets. |
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Figure 2-a:
Distribution of the jet charge (a and b) $Q^\kappa $, (c) $Q_{L}^\kappa $ and (d) $Q_{T}^\kappa $ in data compared to MC simulations. The (a) plot shows for the $\mathrm{ u } $, $\mathrm{ d } $ and $\gamma $ distributions in PYTHIA 6 in comparison with data where each distribution is normalized to its total number of events. The (b), (c) and (d) plots compare the sum of the contributions in PYTHIA 6 and HERWIG ++ to data where the flavor breakdown is carried out in PYTHIA 6. |
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Figure 2-b:
Distribution of the jet charge (a and b) $Q^\kappa $, (c) $Q_{L}^\kappa $ and (d) $Q_{T}^\kappa $ in data compared to MC simulations. The (a) plot shows for the $\mathrm{ u } $, $\mathrm{ d } $ and $\gamma $ distributions in PYTHIA 6 in comparison with data where each distribution is normalized to its total number of events. The (b), (c) and (d) plots compare the sum of the contributions in PYTHIA 6 and HERWIG ++ to data where the flavor breakdown is carried out in PYTHIA 6. |
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Figure 2-c:
Distribution of the jet charge (a and b) $Q^\kappa $, (c) $Q_{L}^\kappa $ and (d) $Q_{T}^\kappa $ in data compared to MC simulations. The (a) plot shows for the $\mathrm{ u } $, $\mathrm{ d } $ and $\gamma $ distributions in PYTHIA 6 in comparison with data where each distribution is normalized to its total number of events. The (b), (c) and (d) plots compare the sum of the contributions in PYTHIA 6 and HERWIG ++ to data where the flavor breakdown is carried out in PYTHIA 6. |
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Figure 2-d:
Distribution of the jet charge (a and b) $Q^\kappa $, (c) $Q_{L}^\kappa $ and (d) $Q_{T}^\kappa $ in data compared to MC simulations. The (a) plot shows for the $\mathrm{ u } $, $\mathrm{ d } $ and $\gamma $ distributions in PYTHIA 6 in comparison with data where each distribution is normalized to its total number of events. The (b), (c) and (d) plots compare the sum of the contributions in PYTHIA 6 and HERWIG ++ to data where the flavor breakdown is carried out in PYTHIA 6. |
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Figure 3:
Variation of the average leading jet charge in PYTHIA 6, HERWIG ++ and data as a function of leading jet ${p_{\mathrm {T}}} $. The error bars for the simulation indicate the uncertainty due to the MC simulation statistics. |
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Figure 4-a:
Distributions of the jet charge of the leading jet at reconstructed level and generated level in PYTHIA 6 with $\kappa =$ 1.0 (a), 0.6 (b), 0.3 (c) respectively. |
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Figure 4-b:
Distributions of the jet charge of the leading jet at reconstructed level and generated level in PYTHIA 6 with $\kappa =$ 1.0 (a), 0.6 (b), 0.3 (c) respectively. |
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Figure 4-c:
Distributions of the jet charge of the leading jet at reconstructed level and generated level in PYTHIA 6 with $\kappa =$ 1.0 (a), 0.6 (b), 0.3 (c) respectively. |
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Figure 5-a:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators. The (a,c,e) plots show the distributions for the default jet charge definition ($Q^\kappa $) with all three different $\kappa $ values, while tthe (b,d,e) plots shows for the longitudinal jet charge definition ($Q_{L}^\kappa $) with all three different values of $\kappa $. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 5-b:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators. The (a,c,e) plots show the distributions for the default jet charge definition ($Q^\kappa $) with all three different $\kappa $ values, while tthe (b,d,e) plots shows for the longitudinal jet charge definition ($Q_{L}^\kappa $) with all three different values of $\kappa $. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 5-c:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators. The (a,c,e) plots show the distributions for the default jet charge definition ($Q^\kappa $) with all three different $\kappa $ values, while tthe (b,d,e) plots shows for the longitudinal jet charge definition ($Q_{L}^\kappa $) with all three different values of $\kappa $. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 5-d:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators. The (a,c,e) plots show the distributions for the default jet charge definition ($Q^\kappa $) with all three different $\kappa $ values, while tthe (b,d,e) plots shows for the longitudinal jet charge definition ($Q_{L}^\kappa $) with all three different values of $\kappa $. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 5-e:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators. The (a,c,e) plots show the distributions for the default jet charge definition ($Q^\kappa $) with all three different $\kappa $ values, while tthe (b,d,e) plots shows for the longitudinal jet charge definition ($Q_{L}^\kappa $) with all three different values of $\kappa $. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 5-f:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators. The (a,c,e) plots show the distributions for the default jet charge definition ($Q^\kappa $) with all three different $\kappa $ values, while tthe (b,d,e) plots shows for the longitudinal jet charge definition ($Q_{L}^\kappa $) with all three different values of $\kappa $. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 6-a:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators for transverse jet charge definition ($Q_{T}^\kappa $) with all different $\kappa $ values. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 6-b:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators for transverse jet charge definition ($Q_{T}^\kappa $) with all different $\kappa $ values. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 6-c:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators for transverse jet charge definition ($Q_{T}^\kappa $) with all different $\kappa $ values. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 7-a:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}} $. Plots (a,c,e) show the jet ${p_{\mathrm {T}}}$ dependence for the default jet charge definition ($Q^\kappa $) with $\kappa $ = 0.6. Plots (b,d,f) shows the jet ${p_{\mathrm {T}}}$ dependence for the longitudinal jet charge definition ($Q_{L}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 7-b:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}} $. Plots (a,c,e) show the jet ${p_{\mathrm {T}}}$ dependence for the default jet charge definition ($Q^\kappa $) with $\kappa $ = 0.6. Plots (b,d,f) shows the jet ${p_{\mathrm {T}}}$ dependence for the longitudinal jet charge definition ($Q_{L}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
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Figure 7-c:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}} $. Plots (a,c,e) show the jet ${p_{\mathrm {T}}}$ dependence for the default jet charge definition ($Q^\kappa $) with $\kappa $ = 0.6. Plots (b,d,f) shows the jet ${p_{\mathrm {T}}}$ dependence for the longitudinal jet charge definition ($Q_{L}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
png pdf |
Figure 7-d:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}} $. Plots (a,c,e) show the jet ${p_{\mathrm {T}}}$ dependence for the default jet charge definition ($Q^\kappa $) with $\kappa $ = 0.6. Plots (b,d,f) shows the jet ${p_{\mathrm {T}}}$ dependence for the longitudinal jet charge definition ($Q_{L}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
png pdf |
Figure 7-e:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}} $. Plots (a,c,e) show the jet ${p_{\mathrm {T}}}$ dependence for the default jet charge definition ($Q^\kappa $) with $\kappa $ = 0.6. Plots (b,d,f) shows the jet ${p_{\mathrm {T}}}$ dependence for the longitudinal jet charge definition ($Q_{L}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
png pdf |
Figure 7-f:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}} $. Plots (a,c,e) show the jet ${p_{\mathrm {T}}}$ dependence for the default jet charge definition ($Q^\kappa $) with $\kappa $ = 0.6. Plots (b,d,f) shows the jet ${p_{\mathrm {T}}}$ dependence for the longitudinal jet charge definition ($Q_{L}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
png pdf |
Figure 8-a:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}}$ for the transverse jet charge definition ($Q_{T}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
png pdf |
Figure 8-b:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}}$ for the transverse jet charge definition ($Q_{T}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
png pdf |
Figure 8-c:
Comparison of unfolded leading jet charge distributions with PYTHIA 6, HERWIG ++ generators in bins of leading jet ${p_{\mathrm {T}}}$ for the transverse jet charge definition ($Q_{T}^\kappa $) with $\kappa $ = 0.6. Shaded uncertainty bands include both statistical and systematic effects, added in quadrature. |
| Tables | |
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Table 1:
Various systematic effects and their corresponding error weighted mean of the fractional deviation in percent. |
| Summary |
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In this paper we presented the first measurement of the jet charge distribution with the CMS experiment. Data distributions from dijet events unfolded for detector effects are provided for different definitions of jet charge and in different jet $p_{\mathrm{T}}$ bins. Three different definitions of jet charge provide different sensitivity to the fragmentation model. Three different $\kappa$ parameter choices provide different sensitivity to the softer and harder particles in the jet. We provided measurements in different leading jet $p_{\mathrm{T}}$ bins with sensitivity to the different composition of the quark and gluon jets in the dijet sample. In general the predictions from PYTHIA 6 and HERWIG++ generators show only mild discrepancies with the data distributions. However, the predictions from PYTHIA 6 and HERWIG++ generators are systematically different and could be constrained by this measurement. |
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