Meson-exchange currents and quasielastic predictions for charged-current neutrino-${}^{12}\mathrm{C}$ scattering in the superscaling approach

We evaluate and discuss the impact of meson-exchange currents (MECs) on charged-current quasielastic neutrino cross sections. We consider the nuclear transverse response arising from two-particle two-hole states excited by the action of electromagnetic, purely isovector meson-exchange currents in a fully relativistic framework based on the work by the Torino Collaboration [A. D. Pace, M. Nardi, W. M. Alberico, T. W. Donnelly, and A. Molinari, Nucl. Phys. A726, 303 (2003)]. An accurate parametrization of this MEC response as a function of the momentum and energy transfers involved is presented. Results of neutrino-nucleus cross sections using this MEC parametrization together with a recent scaling approach for the one-particle one-hole contributions (named SuSAv2) are compared with experimental data.

Figure 1

$R_{T,\mathrm{VV}}^{\mathrm{MEC},\text{param}}$ (${\mathrm{MeV}}^{-1}$) versus ${\mathrm{\Psi }}^{\prime }$ (first three panels) and versus $\omega$ (bottom panel), where for the last one the curves are displayed from left to right in steps of $q=200\mathrm{MeV}/\mathrm{c}$. The parametrized responses are shown as black lines. Comparisons with Torino results (colored thick lines) are also displayed. Note that the $y$ axis in the third panel is shown as a logarithmic scale.

Figure 2

Dependence on $q$ of the fitting parameters $\{a_i,b_k\}$.

Figure 3

Total MEC neutrino cross section per target nucleon evaluated excluding all contributions coming from transferred momentum (upper panel) and energy (lower panel) below some selected values, as indicated in the figure.

Figure 4

Comparison between the total MEC cross section in the present and past parametrizations.

Figure 5

Transverse 2p-2h MEC isovector scaling functions $f_{T,\mathrm{VV}}^{\mathrm{MEC}}$ versus the scaling variable ${\mathrm{\Psi }}^{\prime }$ from $q=400\mathrm{MeV}/\mathrm{c}$ to $1500\mathrm{MeV}/\mathrm{c}$.

Figure 6

Comparison of inclusive ${}^{12}\mathrm{C}(e,e^{\prime })$ cross sections and predictions of the QE(SuSAv2), MEC, and inelastic(SuSAv2) models at different set values of the position of the QE peak ($q_{\mathrm{QE}}$), incident electron energy (${ϵ}_i$), and the scattering angle (${\theta }_e$). Data taken from [40].

Figure 7

Flux-integrated double-differential cross section per target nucleon for the ${\nu }_{\mu }$ CCQE process on ${}^{12}\mathrm{C}$ displayed versus the ${\mu }^{-}$ kinetic energy $T_{\mu }$ for various bins of $\cos {\theta }_{\mu }$ obtained within the SuSAv2 and $\mathrm{SuSAv}2+\mathrm{MECs}$ approaches. MEC results are also shown. The data are from Ref. [2].

Figure 8

As for Fig. 7, but for ${\overline{\nu }}_{\mu }$ scattering versus ${\mu }^{+}$ kinetic energy $T_{\mu }$. The data are from Ref. [3].

Figure 9

Flux-integrated double-differential cross section per target nucleon for the ${\nu }_{\mu }$ CCQE process on ${}^{12}\mathrm{C}$ displayed versus $\cos {\theta }_{\mu }$ for various bins of $T_{\mu }$ obtained within the SuSAv2 and $\mathrm{SuSAv}2+\mathrm{MECs}$ approaches. MEC results are also shown. The data are from Ref. [2].

Figure 10

As for Fig. 9, but for ${\overline{\nu }}_{\mu }$ scattering versus $\cos {\theta }_{\mu }$. The data are from Ref. [3].

Figure 11

CCQE ${\nu }_{\mu }$ cross section per nucleon displayed versus neutrino energy $E_{\nu }$ and evaluated using the SuSAv2 and the $\mathrm{SuSAv}2+\mathrm{MECs}$ approaches (top panel). CCQE ${\overline{\nu }}_{\mu }$ cross section is also shown (bottom panel). Results are compared with the MiniBooNE [2, 3] and NOMAD [7] experimental data. Also presented for reference are the results for the MEC contributions.

Figure 12

Separation into components of the CCQE ${\nu }_{\mu }$ cross section per nucleon displayed versus neutrino energy $E_{\nu }$ within the SuSAv2 approach. The MECs and $\mathrm{SuSAv}2+\mathrm{MECs}$ curves are shown. The MiniBooNE [2] and NOMAD [7] data are also shown for reference.

Figure 13

Experimental difference between neutrino and antineutrino cross sections (${\sigma }_{{\nu }_{\mu }}-{\sigma }_{{\overline{\nu }}_{\mu }}$) from MiniBooNE, together with the corresponding theoretical prediction from $\mathrm{SuSAv}2+\mathrm{MECs}$, whose difference with the SuSAv2 prediction is negligible.

Figure 14

Separation into components of the MiniBooNE CCQE ${\nu }_{\mu }$ (top panel) and ${\overline{\nu }}_{\mu }$ (bottom panel) double-differential cross section per nucleon displayed versus $T_{\mu }$ for various bins of $\cos {\theta }_{\mu }$ within the SuSAv2 approach. The MECs and $\mathrm{SuSAv}2+\mathrm{MECs}$ curves are shown. The MiniBooNE [2, 3] data are also shown for reference.

Figure 15

Separation into components of the MiniBooNE CCQE ${\nu }_{\mu }$ (top panel) and ${\overline{\nu }}_{\mu }$ (bottom panel) double-differential cross section per nucleon displayed versus $\cos {\theta }_{\mu }$ for various bins of $T_{\mu }$ within the SuSAv2 approach. The MECs and $\mathrm{SuSAv}2+\mathrm{MECs}$ curves are shown. The MiniBooNE [2, 3] data are also shown for reference.

Figure 16

CCQE ${\nu }_{\mu }$ cross section per nucleon displayed versus neutrino energy $E_{\nu }$ and evaluated using the SuSAv2 and the $\mathrm{SuSAv}2+\mathrm{MECs}$ approaches. Results are compared with the MiniBooNE [2, 3], NOMAD [7], and T2K [43] experimental data. Also presented for reference are the results for the MEC contributions.

Figure 17

As for Fig. 3, but for the $\mathrm{SuSAv}2+\mathrm{MECs}$ CCQE cross section. The MiniBooNE [2] and NOMAD [7] data are also shown for reference.

Figure 18

Flux-folded CCQE ${\nu }_{\mu }-{}^{12}\mathrm{C}$ (upper panel) and ${\overline{\nu }}_{\mu }-\mathrm{CH}$ (lower panel) scattering cross section per target nucleon as a function of $Q_{\mathrm{QE}}^2$ and evaluated in the SuSAv2 and $\mathrm{SuSAv}2+\mathrm{MECs}$ models. $\mathrm{MINER}\nu \mathrm{A}$ data are from [4, 5].

Figure 19

Flux-folded CCQE ${\nu }_{\mu }-{}^{12}\mathrm{C}$ (upper panel) and ${\overline{\nu }}_{\mu }-{}^{12}\mathrm{C}$ (lower panel) scattering cross section per target nucleon as a function of $Q_{\mathrm{QE}}^2$ and evaluated in the SuSAv2 and $\mathrm{SuSAv}2+\mathrm{MECs}$ models. MiniBooNE data are from [2, 3].