Constraints on nonstandard intermediate boson exchange models from neutrino-electron scattering

Constraints on couplings of several beyond-Standard-Model-physics scenarios, mediated by massive intermediate particles including (1) an extra Z-prime, (2) a new light spin-1 boson, and (3) a charged Higgs boson, are placed via the neutrino-electron scattering channel to test the Standard Model at a low energy-momentum transfer regime. Data on ${\overline{\nu }}_{\mathrm{e}}-\mathrm{e}$ and ${\nu }_{\mathrm{e}}-\mathrm{e}$ scattering from the TEXONO and LSND, respectively, are used. Upper bounds to coupling constants of the flavor-conserving and flavor-violating new light spin-1 boson and the charged Higgs boson with respect to different mediator masses are determined. The relevant parameter spaces are extended by allowing light mediators. New lower mass limits for extra Z-prime gauge boson models are also placed.

Figure 1

Feynman diagram for ${\nu }_{\mathrm{e}}({\overline{\nu }}_{\mathrm{e}})-e$ via exchange of massive mediators such as the virtual $Z^{\prime }$ or NLS1B.

Figure 2

Differential cross section as a function of the recoil energy $T$ with typical reactor ${\overline{\nu }}_{\mathrm{e}}$ spectra for extra $Z^{\prime }$ models for a specific $\gamma$ value using CsI(Tl) as a target, where $\gamma ={(M_Z/M_{Z^{\prime }})}^2$. The SM contributions are superimposed for comparison.

Figure 3

The lower limit for the mass of $Z^{\prime }$ at 95% C.L. using the TEXONO CsI(Tl) and HP-Ge detector data sets for the mixing-parameter-independent case of the E6-string-type model. Projected sensitivities by improving the experimental accuracies to 1% are superimposed.

Figure 4

Differential cross section as a function of the recoil energy $T$ with typical reactor ${\overline{\nu }}_{\mathrm{e}}$ spectra for the NLS1B at some specific coupling and mass parameters relevant to this work using Ge as a target for both the FC and FV cases. The SM contributions are superimposed for comparison.

Figure 5

The allowed regions at 90% C.L. for (a) the FC NLS1B in the parameter space of ${ϵ}_{ee}^L$ and ${ϵ}_{ee}^R$; (b) FV NLS1B in the parameter space of ${ϵ}_{e\mu (\tau )}^L$ and ${ϵ}_{e\mu (\tau )}^R$ for TEXONO CsI(Tl) with various $m_X=1$, 2, 5, 25 MeV, from outer to inner, respectively; (c) FC NLS1B in the parameter space of ${ϵ}_{ee}^L$ and ${ϵ}_{ee}^R$; (d) FV NLS1B in the parameter space of ${ϵ}_{e\mu (\tau )}^L$ and ${ϵ}_{e\mu (\tau )}^R$ for LSND with various $m_X=3$, 4, 5, 25 MeV, from outer to inner, respectively, with the global fitting for allowed regions of TEXONO CsI(Tl) and LSND at 90% C.L. for (e) FC NLS1B couplings of ${ϵ}_{ee}^L$ vs ${ϵ}_{ee}^R$ and (f) FV NLS1B couplings of ${ϵ}_{e\mu (\tau )}^L$ vs ${ϵ}_{e\mu (\tau )}^R$ with various $m_X=1$, 2, 5, 25 MeV from outer to inner, respectively.

Figure 6

The 90% C.L. upper limits for the couplings of (a) $|L_{ee}{|}^{1/2}$, (b) $|R_{ee}{|}^{1/2}$, (c) $|V_{ee}{|}^{1/2}$, (d) $|A_{ee}{|}^{1/2}$, (e) $|L_{e\mu (\tau )}{|}^{1/2}$, (f) $|R_{e\mu (\tau )}{|}^{1/2}$, (g) $|V_{e\mu (\tau )}{|}^{1/2}$, and (h) $|A_{e\mu (\tau )}{|}^{1/2}$ for TEXONO and LSND with various $m_X$ values by adopting a one-parameter-at-a-time analysis.

Figure 7

The allowed regions at 90% C.L. for (a) the FC NLS1B in the parameter space of ${ϵ}_{ee}^V$ and ${ϵ}_{ee}^A$; (b) FV NLS1B in the parameter space of ${ϵ}_{e\mu (\tau )}^V$ and ${ϵ}_{e\mu (\tau )}^A$ for TEXONO CsI(Tl) with various $m_X=1$, 2, 5, 25 MeV, from outer to inner, respectively; (c) FC NLS1B in the parameter space of ${ϵ}_{ee}^V$ and ${ϵ}_{ee}^A$; (d) FV NLS1B in the parameter space of ${ϵ}_{e\mu (\tau )}^V$ and ${ϵ}_{e\mu (\tau )}^A$ for LSND with various $m_X=3$, 4, 5, 25 MeV, from outer to inner, respectively, with the global fitting for allowed regions of TEXONO CsI(Tl) and LSND at 90% C.L. for (e) FC NLS1B couplings of ${ϵ}_{ee}^V$ vs ${ϵ}_{ee}^A$, and (f) FV NLS1B couplings of ${ϵ}_{e\mu (\tau )}^V$ vs ${ϵ}_{e\mu (\tau )}^A$ with various $m_X=1$, 2, 5, 25 MeV from outer to inner, respectively.

Figure 8

Feynman diagrams of (a) ${\overline{\nu }}_{\mathrm{e}}-\mathrm{e}$ scattering and (b) ${\nu }_{\mathrm{e}}-\mathrm{e}$ scattering for the exchange of charged Higgs boson.

Figure 9

Differential cross section as a function of recoil energy $T$ with a typical reactor ${\overline{\nu }}_{\mathrm{e}}$ spectrum for the exchange of CHB. The SM differential cross section is superimposed for comparison.

Figure 10

The upper limit of coupling $h_{ee}$ with respect to the mass of CHB $M_H$ at 90% C.L. for (a) low and (b) high mass values.