We report results from the first search for ${\nu }_{\mu }\to {\nu }_e$ transitions by the NOvA experiment. In an exposure equivalent to $2.74\times {10}^{20}$ protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of $0.99\pm 0.11(\text{syst})$ events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of $1.07\pm 0.14(\text{syst})$. The $3.3\sigma$ excess of events observed in the primary analysis disfavors $0.1\pi <{\delta }_{CP}<0.5\pi$ in the inverted mass hierarchy at the 90% C.L.

We present updated results from the NOvA experiment for ${\nu }_{\mu }\to {\nu }_{\mu }$ and ${\nu }_{\mu }\to {\nu }_e$ oscillations from an exposure of $8.85\times {10}^{20}$ protons on target, which represents an increase of 46% compared to our previous publication. The results utilize significant improvements in both the simulations and analysis of the data. A joint fit to the data for ${\nu }_{\mu }$ disappearance and ${\nu }_e$ appearance gives the best-fit point as normal mass hierarchy, $\mathrm{\Delta }{m}_{32}^2=2.44\times {10}^{-3}{\mathrm{eV}}^2/c^4$, ${\sin }^2{\theta }_{23}=0.56$, and ${\delta }_{\mathrm{CP}}=1.21\pi$. The 68.3% confidence intervals in the normal mass hierarchy are $\mathrm{\Delta }{m}_{32}^2\in [2.37,2.52]\times {10}^{-3}{\mathrm{eV}}^2/c^4$, ${\sin }^2{\theta }_{23}\in [0.43,0.51]\cup [0.52,0.60]$, and ${\delta }_{\mathrm{CP}}\in [0,0.12\pi ]\cup [0.91\pi ,2\pi ]$. The inverted mass hierarchy is disfavored at the 95% confidence level for all choices of the other oscillation parameters.

Results are reported from an improved measurement of ${\nu }_{\mu }\to {\nu }_e$ transitions by the NOvA experiment. Using an exposure equivalent to $6.05\times 10^{20}$ protons on target, 33 ${\nu }_e$ candidates are observed with a background of $8.2\pm 0.8$ (syst.). Combined with the latest NOvA ${\nu }_{\mu }$ disappearance data and external constraints from reactor experiments on ${\sin }^{2}2{\theta }_{13}$, the hypothesis of inverted mass hierarchy with ${\theta }_{23}$ in the lower octant is disfavored at greater than 93% C.L. for all values of ${\delta }_{CP}$.

Recently, the $B$ factories BABAR and Belle as well as the LHCb experiment have reported several anomalies in the semileptonic $B$ meson decays, such as the $R_K$ and $R_{D^{(*)}}$ etc. We investigate these deviations by considering the vector leptoquarks relevant for both $b\to s{l}^{+}{l}^{-}$ and $b\to cl{\overline{\nu }}_l$ transitions. The leptoquark parameter space is constrained by using the experimentally measured branching ratios of $B_s\to l^{+}{l}^{-}$, $\overline{B}\to X_s{l}^{+}{l}^{-}(\nu \overline{\nu })$, and $B_u^{+}\to l^{+}{\nu }_l$ processes. Using the constrained leptoquark couplings, we compute the branching ratios, forward-backward asymmetries, $\tau$, and $D^{*}$ polarization parameters in the $\overline{B}\to D^{(*)}l{\overline{\nu }}_l$ processes. We find that the vector leptoquarks can explain both the $R_{D^{(*)}}$ and $R_K$ anomalies, simultaneously. Furthermore, we study the rare leptonic $B_{u,c}^{*}\to l\overline{\nu }$ decay processes in this model.

We study some rare decays of $B$ mesons involving the quark-level transition $b\to q{l}^{+}{l}^{-}(q=d,s)$ in the scalar leptoquark model. We constrain the leptoquark parameter space using the recently measured branching ratios of $B_{s,d}\to {\mu }^{+}{\mu }^{-}$ processes. Using such parameters, we obtain the branching ratios, direct $CP$-violation parameters, and isospin asymmetries in the $B\to K{\mu }^{+}{\mu }^{-}$ and $B\to \pi {\mu }^{+}{\mu }^{-}$ processes. We also obtain the branching ratios for some lepton-flavor-violating decays $B\to l_i^{+}{l}_j^{-}$. We find that the various anomalies associated with the isospin asymmetries of the $B\to K{\mu }^{+}{\mu }^{-}$ process can be explained in the scalar leptoquark model.

This paper reports the first measurement using the NOvA detectors of ${\nu }_{\mu }$ disappearance in a ${\nu }_{\mu }$ beam. The analysis uses a 14 kton-equivalent exposure of $2.74\times {10}^{20}$ protons-on-target from the Fermilab NuMI beam. Assuming the normal neutrino mass hierarchy, we measure $\mathrm{\Delta }{m}_{32}^2=({2.52}_{-0.18}^{+0.20})\times {10}^{-3}{\mathrm{eV}}^2$ and ${\sin }^2{\theta }_{23}$ in the range 0.38–0.65, both at the 68% confidence level, with two statistically degenerate best-fit points at ${\sin }^2{\theta }_{23}=0.43$ and 0.60. Results for the inverted mass hierarchy are also presented.