First combined measurement of the muon neutrino and antineutrino charged-current cross section without pions in the final state at T2K

This paper presents the first combined measurement of the double-differential muon neutrino and antineutrino charged-current cross sections with no pions in the final state on hydrocarbon at the off-axis near detector of the T2K experiment. The data analyzed in this work comprise $5.8\times {10}^{20}$ and $6.3\times {10}^{20}$ protons on target in neutrino and antineutrino mode respectively, at a beam energy peak of 0.6 GeV. Using the two measured cross sections, the sum, difference, and asymmetry were calculated with the aim of better understanding the nuclear effects involved in such interactions. The extracted measurements have been compared with the prediction from different Monte Carlo generators and theoretical models showing that the difference between the two cross sections have interesting sensitivity to nuclear effects.

Figure 1

The predicted flux as a function of energy at the ND280 detector, for the neutrino beam (forward horn current) on top and antineutrino beam (reverse horn current) on bottom. In each case, the ${\nu }_{\mu },{\overline{\nu }}_{\mu },{\nu }_e$, and ${\overline{\nu }}_e$ components of the beam are shown.

Figure 2

Schematic showing an exploded view of the ND280 off-axis detector. Each subdetector is labeled using the acronyms given in the text.

Figure 3

Schematic representation of the different ${\nu }_{\mu }$ CC signal samples. In each drawing a ${\nu }_{\mu }$ enters from the left and interacts in FGD1. The subdetectors of ND280 are shown in their side view.

Figure 4

Distribution of events in the different signal samples for the neutrino sample. In the left column the number of events are plotted against the reconstructed muon momentum, while in the right column against the reconstructed muon $\cos {\theta }_{\mu }$. Histograms are stacked in true topologies. The last bin of the reconstructed muon momentum distributions contains all the events with momentum greater than $5\mathrm{GeV}/\mathrm{c}$ for the first three samples, and $2\mathrm{GeV}/\mathrm{c}$ for the last two. The MC has been normalized to $5.80\times {10}^{20}$ p.o.t., the number of p.o.t. in data. The legends show also the fraction for each component.

Figure 5

Distribution of events in the two control samples for the neutrino sample: $\mathrm{CC}\text{−}1{\pi }^{+}$ in the top row and CC-Other in the bottom. In the left column number of events per bin are plotted against the reconstructed muon momentum, while in the right column against the reconstructed muon $\cos {\theta }_{\mu }$. The last bin of the reconstructed muon momentum distributions contains all the events with momentum greater than $5\mathrm{GeV}/\mathrm{c}$. Histograms are stacked in true topologies. The MC has been normalized to $5.80\times {10}^{20}$ p.o.t, the number of p.o.t in data. The legends show also the fraction for each component.

Figure 6

Schematic representation of the different ${\overline{\nu }}_{\mu }$ signal samples. In each drawing a ${\overline{\nu }}_{\mu }$ enters from the left and interacts in FGD1. The subdetectors of ND280 are shown in their side view.

Figure 7

Distribution of events in the different signal samples (${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ FWD, BWD, HAFWD, and HABWD). In the left column the number of events per bin are plotted against the reconstructed muon momentum, while in the right column against the reconstructed muon $\cos {\theta }_{\mu }$. The last bin of the reconstructed muon momentum distributions contains all the events with momentum greater than $5\mathrm{GeV}/\mathrm{c}$ for the first sample, and $2\mathrm{GeV}/\mathrm{c}$ for the others. The MC has been normalized to $6.27\times {10}^{20}$ p.o.t., the number of p.o.t. in data. Histograms are stacked in true topologies. The legends show also the fraction for each component.

Figure 8

Distribution of events in the two sidebands for the antineutrino sample: $\mathrm{CC}\text{−}1{\pi }^{-}$ in the top row and CC-Other in the bottom. In the left column the number of events are plotted against the reconstructed muon momentum, while in the right column against the reconstructed muon $\cos {\theta }_{\mu }$. The last bin of the reconstructed muon momentum distributions contains all the events with momentum greater than $5\mathrm{GeV}/\mathrm{c}$. Histograms are stacked in true topologies. The MC has been normalized to $6.27\times {10}^{20}$ p.o.t, the number of p.o.t. in data. The legends show also the fraction for each component.

Figure 9

Summary of all of the systematic uncertainties for the ${\nu }_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section, in bins of true muon kinematics.

Figure 10

Summary of all of the systematic uncertainties for the ${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section, in bins of true muon kinematics.

Figure 11

Distribution of events in ${\nu }_{\mu }$ signal samples added together as a function of reconstructed muon kinematics compared with the MC prediction before the fit (dotted blue line), and after the fit (solid red line) including systematics errors indicated by the pink band. The data are shown in black with statistical errors.

Figure 12

Distribution of events in ${\overline{\nu }}_{\mu }$ signal samples added together as a function of reconstructed muon kinematics compared with the MC prediction before the fit (dotted blue line), and after the fit (solid red line) including systematics errors indicated by the pink band. The data are shown in black with statistical errors.

Figure 13

Distribution of events in the ${\nu }_{\mu }$ $\mathrm{CC}\text{−}1{\pi }^{+}$ (top) and CC-Other control samples (bottom), as a function of muon momentum (left) and muon $\cos \theta$ (right) compared with the MC predictions before the fit (dotted blue line), and those after the fit (solid red line) including systematics errors indicated by the pink band. The data are shown in black with statistical errors.

Figure 14

Distribution of events in the ${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}1{\pi }^{-}$ (top) and CC-Other control samples (bottom), as a function of muon momentum (left) and muon $\cos \theta$ (right) compared with the MC predictions before the fit (dotted blue line), and those after the fit (solid red line) including systematics errors indicated by the pink band. The data are shown in black with statistical errors.

Figure 15

Measured ${\nu }_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model, with (solid line) and without (dashed line) 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 16

Measured ${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model, with (solid line) and without (dashed line) 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 17

Measured double-differential ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section sum in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model, with (solid line) and without (dashed line) 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 18

Measured double-differential ${\nu }_{\mu }$−${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section difference in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model, with (solid line) and without (dashed line) 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 19

Measured double-differential $\mathrm{CC}\text{−}0\pi$ cross section asymmetry in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model, with (solid line) and without (dashed line) 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 20

Measured ${\nu }_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model with 2p2h (solid red line), Martini et al. (dashed blue line) and susav2 (green dashed line) models. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 21

Measured ${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model with 2p2h (solid red line), Martini et al. (dashed blue line) and susav2 (green dashed line) models. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 22

Measured double-differential ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section sum in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model with 2p2h (solid red line), Martini et al. (dashed blue line) and susav2 (green dashed line) models. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 23

Measured double-differential ${\nu }_{\mu }$−${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section difference in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model with 2p2h (solid red line), Martini et al. (dashed blue line) and susav2 (green dashed line) models. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 24

Measured double-differential $\mathrm{CC}\text{−}0\pi$ cross section asymmetry in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The results are compared to neut version 5.4.1, which uses an $\mathrm{LFG}+\mathrm{RPA}$ model with 2p2h (solid red line), Martini et al. (dashed blue line) and susav2 (green dashed line) models. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 25

Measured ${\nu }_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with neut (dashed blue line), nuwro version 18.02.1 (green solid line) and gibuu 2019 (pink dotted line) prediction. All generators use an $\mathrm{LFG}+\mathrm{RPA}$ model that includes 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 26

Measured ${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with neut (dashed blue line), nuwro version 18.02.1 (green solid line) and gibuu 2019 (pink dotted line) prediction. All generators use an $\mathrm{LFG}+\mathrm{RPA}$ model that includes 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 27

Measured double-differential ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section sum in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with neut (dashed blue line), nuwro version 18.02.1 (green solid line) and gibuu 2019 (pink dotted line) prediction. All generators use an $\mathrm{LFG}+\mathrm{RPA}$ model that includes 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 28

Measured double-differential ${\nu }_{\mu }$−${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section difference in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with neut (dashed blue line), nuwro version 18.02.1 (green solid line) and gibuu 2019 (pink dotted line) prediction. All generators use an $\mathrm{LFG}+\mathrm{RPA}$ model that includes 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 29

Measured double-differential $\mathrm{CC}\text{−}0\pi$ cross section asymmetry in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with neut (dashed blue line), nuwro version 18.02.1 (green solid line) and gibuu 2019 (pink dotted line) prediction. All generators use an $\mathrm{LFG}+\mathrm{RPA}$ model that includes 2p2h. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 30

Measured ${\nu }_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with nuwro version 18.02.1 with $\mathrm{LFG}+\mathrm{RPA}$ (green solid line) and with the SF nuclear model (green dashed line), both including 2p2h predictions. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 31

Measured ${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ double-differential cross section per nucleon in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with nuwro version 18.02.1 with $\mathrm{LFG}+\mathrm{RPA}$ (green solid line) and with the SF nuclear model (green dashed line), both including 2p2h predictions. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 32

Measured double-differential ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section sum in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with nuwro version 18.02.1 with $\mathrm{LFG}+\mathrm{RPA}$ (green solid line) and with the SF nuclear model (green dashed line), both including 2p2h predictions. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 33

Measured double-differential ${\nu }_{\mu }$−${\overline{\nu }}_{\mu }$ $\mathrm{CC}\text{−}0\pi$ cross section difference in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with nuwro version 18.02.1 with $\mathrm{LFG}+\mathrm{RPA}$ (green solid line) and with the SF nuclear model (green dashed line), both including 2p2h predictions. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.

Figure 34

Measured double-differential $\mathrm{CC}\text{−}0\pi$ cross section asymmetry in bins of true muon kinematics with systematic uncertainty (red bars) and total ($\mathrm{stat}.+\mathrm{syst}.$) uncertainty (black bars). The result is compared with nuwro version 18.02.1 with $\mathrm{LFG}+\mathrm{RPA}$ (green solid line) and with the SF nuclear model (green dashed line), both including 2p2h predictions. The full and shape-only (in parenthesis) $\chi 2$ are reported. The last bin in momentum is not displayed for readability.