Prospects for beyond the Standard Model physics searches at the Deep Underground Neutrino Experiment: DUNE Collaboration

Abstract

The Deep Underground Neutrino Experiment (DUNE) will be a powerful tool for a variety of physics topics. The high-intensity proton beams provide a large neutrino flux, sampled by a near detector system consisting of a combination of capable precision detectors, and by the massive far detector system located deep underground. This configuration sets up DUNE as a machine for discovery, as it enables opportunities not only to perform precision neutrino measurements that may uncover deviations from the present three-flavor mixing paradigm, but also to discover new particles and unveil new interactions and symmetries beyond those predicted in the Standard Model (SM). Of the many potential beyond the Standard Model (BSM) topics DUNE will probe, this paper presents a selection of studies quantifying DUNE's sensitivities to sterile neutrino mixing, heavy neutral leptons, non-standard interactions, CPT symmetry violation, Lorentz invariance violation, neutrino trident production, dark matter from both beam induced and cosmogenic sources, baryon number violation, and other new physics topics that complement those at high-energy colliders and significantly extend the present reach.

Fig. 1

Regions of L/E probed by the DUNE detector compared to 3-flavor and $3+1$-flavor neutrino disappearance and appearance probabilities. The gray-shaded areas show the range of true neutrino energies probed by the ND and FD. The top axis shows true neutrino energy, increasing from right to left. The top plot shows the probabilities assuming mixing with one sterile neutrino with $\Delta m_{41}^2=0.05{\text{eV}}^2$, corresponding to the slow oscillations regime. The middle plot assumes mixing with one sterile neutrino with $\Delta m_{41}^2=0.5{\text{eV}}^2$, corresponding to the intermediate oscillations regime. The bottom plot includes mixing with one sterile neutrino with $\Delta m_{41}^2=50{\text{eV}}^2$, corresponding to the rapid oscillations regime. As an example, the slow sterile oscillations cause visible distortions in the three-flavor ${\nu }_{\mu }$  survival probability (blue curve) for neutrino energies $\sim 10\text{GeV}$, well above the three-flavor oscillation minimum

Fig. 2

The top plot shows the DUNE sensitivities to ${\theta }_{14}$ from the ${\nu }_e$ CC samples at the ND and FD, along with a comparison with the combined reactor result from Daya Bay and Bugey-3. The bottom plot is adapted from Ref. [18] and displays sensitivities to ${\theta }_{24}$ using the ${\nu }_{\mu }$ CC and NC samples at both detectors, along with a comparison with previous and existing experiments. In both cases, regions to the right of the contours are excluded

Fig. 3

Comparison of the DUNE sensitivity to ${\theta }_{34}$ using the NC samples at the ND and FD with previous and existing experiments. Regions to the right of the contour are excluded

Fig. 4

DUNE sensitivities to ${\theta }_{\mu e}$ from the appearance and disappearance samples at the ND and FD are shown on the top plot, along with a comparison with previous existing experiments and the sensitivity from the future SBN program. Regions to the right of the DUNE contours are excluded. The plot is adapted from Ref. [18]. In the bottom plot, the ellipse displays the DUNE discovery potential assuming ${\theta }_{\mu e}$ and $\Delta m_{41}^2$ set at the best-fit point determined by LSND [19] (represented by the star) for the best-case scenario referenced in the text

Fig. 5

The impact of non-unitarity on the DUNE CPV discovery potential. See the text for details

Fig. 6

Expected frequentist allowed regions at the $1\sigma$, $90\%$ and $2\sigma$ CL for DUNE. All new physics parameters are assumed to be zero so as to obtain the expected non-unitarity sensitivities. A value ${\theta }_{23}=0.235\pi \approx 0.738$ rad is assumed. The solid lines correspond to the analysis of DUNE data alone, while the dashed lines include the present constraints on non-unitarity. The values of ${\theta }_{23}$ are shown in radians

Fig. 7

Allowed regions of the non-standard oscillation parameters in which we see important degeneracies (top) and the complex non-diagonal ones (bottom). We conduct the analysis considering all the NSI parameters as non-negligible. The sensitivity regions are for 68% CL [red line (left)], 90% CL [green dashed line (middle)], and 95% CL [blue dotted line (right)]. Current bounds are taken from [78]

Fig. 8

Projections of the standard oscillation parameters with nonzero NSI. The sensitivity regions are for 68, 90, and 95% CL. The allowed regions considering negligible NSI (standard oscillation (SO) at 90% CL) are superposed to the SO + NSI

Fig. 9

One-dimensional DUNE constraints compared with current constraints calculated in Ref. [55]. The left half of the figure shows constraints on the standard oscillation parameters, written in the bottom of each comparison. The five comparisons in the right half show constraints on non-standard interaction parameters

Fig. 10

The sensitivities of DUNE to the difference of neutrino and antineutrino parameters: $\Delta \delta$, $\Delta (\Delta m_{31}^2)$, $\Delta ({sin}^2{\theta }_{13})$ and $\Delta ({sin}^2{\theta }_{23})$ for the atmospheric angle in the lower octant (black line), in the upper octant (light gray line) and for maximal mixing (dark gray line)

Fig. 11

DUNE sensitivity to the atmospheric angle for neutrinos (blue), antineutrinos (red), and to the combination of both under the assumption of CPT conservation (black)

Fig. 12

Estimated sensitivity to Lorentz and CPT violation with atmospheric neutrinos in the non-minimal isotropic Standard Model Extension. The sensitivities are estimated by requiring that the Lorentz/CPT-violating effects are comparable in size to those from conventional neutrino oscillations

Fig. 13

Atmospheric fluxes of neutrinos and antineutrinos as a function of energy for conventional oscillations (dashed line) and in the non-minimal isotropic Standard Model Extension (solid line)

Fig. 14

Example diagrams for muon-neutrino-induced trident processes in the Standard Model. A second set of diagrams where the photon couples to the negatively charged leptons is not shown. Analogous diagrams exist for processes induced by different neutrino flavors and by antineutrinos. A diagram illustrating trident interactions mediated by a new $Z^{\prime }$ gauge boson, discussed in the text, is shown on the top right

Fig. 15

Event kinematic distributions of signal and background considered for the selection of muonic trident interactions in the ND LArTPC: number of tracks (top left), angle between the two main tracks (top right), length of the shortest track (bottom left), and the difference in length between the two main tracks (bottom right). The dashed, black vertical lines indicate the optimal cut values used in the analysis

Fig. 16

95% CL sensitivity of a 40% (blue hashed regions) and a 25% (dashed contours) uncertainty measurement of the ${\nu }_{\mu }N\to {\nu }_{\mu }{\mu }^{+}{\mu }^{-}N$ cross section at the DUNE near detector to modifications of the vector and axial-vector couplings of muon-neutrinos to muons. The gray regions are excluded at 95% CL by existing measurements of the cross section by the CCFR Collaboration. The intersection of the thin black lines indicates the SM point. A 40% precision measurement could be possible with 6 years of data taking in neutrino mode

Fig. 17

Existing constraints and projected DUNE sensitivity in the $L_{\mu }-L_{\tau }$ parameter space. Shown in green is the region where the ${(g-2)}_{\mu }$ anomaly can be explained at the $2\sigma$ level. The parameter regions already excluded by existing constraints are shaded in gray and correspond to a CMS search for $pp\to {\mu }^{+}{\mu }^{-}{Z}^{\prime }\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ [160] (“LHC”), a BaBar search for $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{Z}^{\prime }\to {\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$ [161] (“BaBar”), a previous measurement of the trident cross section [146, 151] (“CCFR”), a measurement of the scattering rate of solar neutrinos on electrons [–164] (“Borexino”), and bounds from Big Bang Nucleosynthesis [165, 166] (“BBN”). The DUNE sensitivity shown by the solid blue line assumes 6 years of data running in neutrino mode, leading to a measurement of the trident cross section with 40% precision

Fig. 18

Production of fermionic DM via two-body pseudoscalar meson decay $\mathfrak{m}\to \gamma V$, when $M_V<m_{\mathfrak{m}}$ (top) or via three-body decay $\mathfrak{m}\to \gamma \chi \overline{\chi }$ (center) and DM-electron elastic scattering (bottom)

Fig. 19

Expected DUNE On-axis (solid red) and PRISM (dashed red) sensitivity using $\chi e^{-}\to \chi e^{-}$ scattering. We assume ${\alpha }_D=0.5$ in both panels, and $M_V=3M_{\chi }$ ($M_{\chi }=20\text{MeV}$) in the left (right) panel, respectively. Existing constraints are shown in grey, and the relic density target is shown as a black line. We also show for comparison the sensitivity curve expected for LDMX-Phase I (solid blue) [193]

Fig. 20

The inelastic BDM signal under consideration

Fig. 21

The experimental sensitivities in terms of reference model parameters $M_V-ϵ$ for $M_{\Psi }=0.4\text{GeV}$, $M_{\chi }=5\text{MeV}$, and $\delta M=M_{{\chi }^{\prime }}-M_{\chi }=10\text{MeV}$ (top-left panel) and $M_{\Psi }=2\text{GeV}$, $M_{{\chi }^{\prime }}=50\text{MeV}$, and $\delta M=10\text{MeV}$ (top-right panel). The left panels are for Scenario 1 and the right ones are for Scenario 2. The bottom panels compare different reference points in the p-scattering channel. See the text for the details

Fig. 22

Top: model-independent experimental sensitivities of iBDM search in ${\overline{\ell }}_{\mathrm{lab}}^{\max }-{\sigma }_{ϵ}·\mathcal{F}$ plane. The reference experiments are DUNE $20\text{kt}$ (green), and DUNE $40\text{kt}$ (blue) with zero-background assumption for 1-year time exposure. Bottom: Experimental sensitivities of iBDM search in $M_{\Psi }-{\sigma }_{ϵ}$ plane. The sensitivities for ${\overline{\ell }}_{\mathrm{lab}}^{\max }=0$ and 100 m are shown as solid and dashed lines for each reference experiment in the top panel

Fig. 23

The chain of processes leading to boosted DM signal from the sun. The semi-annihilation and two-component DM models refer to the two examples of the non-minimal dark-sector scenarios introduced in the beginning of Sect. 8. DM${}^{\prime }$ denotes the lighter DM in the two-component DM model. X is a lighter dark sector particle that may decay away

Fig. 24

Diagram illustrating each of the three processes contributing to dark matter scattering in argon: elastic (left), baryon resonance (middle), and deep inelastic (right)

Fig. 25

Angular distribution of the BDM signal events for a BDM mass of 10 GeV and different boosted factors, $\gamma$, and of the atmospheric neutrino NC background events. $\theta$ represents the angle of the sum over all the stable final state particles as detailed in the text. The amount of background represents 1-year data collection, magnified by a factor 100, while the amount of signal reflects the detection efficiency of 10,000 MC events. The top plot shows the scenario where neutrons can be reconstructed, while the bottom plot represents the scenario without neutrons

Fig. 26

Expected $5\sigma$ discovery reach with one year of DUNE livetime for one $10\text{kt}$ module including neutrons in reconstruction (top) and excluding neutrons (bottom)

Fig. 27

Comparison of sensitivity of DUNE for 10 years of data collection and $40\text{kt}$ of detector mass with Super Kamiokande, assuming 10 and 100% of the selection efficiency on the atmospheric neutrino analysis in Ref. [222], and with the reinterpretations of the current results from PICO-60 [223] and PandaX [224]. The samples with two boosted factors, $\gamma =1.25$ (top) and $\gamma =10$ (bottom), are also presented

Fig. 28

Kinetic energy of kaons in simulated proton decay events, $p\to K^{+}\overline{\nu }$, in DUNE. The kinetic energy distribution is shown before and after final state interactions in the argon nucleus

Fig. 29

Tracking efficiency for kaons in simulated proton decay events, $p\to K^{+}\overline{\nu }$, as a function of kaon kinetic energy (top) and true path length (bottom)

Fig. 30

Particle identification using PIDA for muons and kaons in simulated proton decay events, $p\to K^{+}\overline{\nu }$, and protons in simulated atmospheric neutrino background events. The curves are normalized by area

Fig. 31

Boosted Decision Tree response for $p\to K^{+}\overline{\nu }$ for signal (blue) and background (red)

Fig. 32

Event display for an easily recognizable $p\to K^{+}\overline{\nu }$ signal event. The vertical axis is TDC value, and the horizontal axis is wire number. The bottom view is induction plane one, the middle is induction plane two, and the top is the collection plane. Hits associated with the reconstructed muon track are shown in red, and hits associated with the reconstructed kaon track are shown in green. Hits from the decay electron can be seen at the end of the muon track

Fig. 33

Event display for an atmospheric neutrino interaction, ${\nu }_{\mu }n\to {\mu }^{-}p$, which might be selected in the $p\to K^{+}\overline{\nu }$ sample if the proton is misidentified as a kaon. The vertical axis is TDC value, and the horizontal axis is wire number. The bottom view is induction plane one, the middle is induction plane two, and the top is the collection plane. Hits associated with the reconstructed muon track are shown in red, and hits associated with the reconstructed proton track are shown in green. Hits from the decay electron can be seen at the end of the muon track

Fig. 34

Top: momentum of an individual charged pion before and after final state interactions. Bottom: momentum of an individual neutral pion before and after final state interactions

Fig. 35

Boosted Decision Tree response for $n-\overline{n}$ oscillation for signal (blue) and background (red)

Fig. 36

Event display for an $n-\overline{n}$ signal event, $n\overline{n}\to n{\pi }^0{\pi }^0{\pi }^{+}{\pi }^{-}$. The vertical axis is TDC value, and the horizontal axis is wire number. The bottom view is induction plane one, the middle is induction plane two, and the top is the collection plane. Hits associated with the back-to-back tracks of the charged pions are shown in red. The remaining hits are from the showers from the neutral pions, neutron scatters, and low-energy de-excitation gammas

Fig. 37

Event display for a NC DIS interaction initiated by an atmospheric neutrino. The vertical axis is TDC value, and the horizontal axis is wire number. The bottom view is induction plane one, the middle is induction plane two, and the top is the collection plane. This event mimics the $n-\overline{n}$ signal topology by having multi-particle production and electromagnetic showers

Fig. 38

The 1$\sigma$ (dashed) and 3$\sigma$ (solid) expected sensitivity for measuring $\Delta m_{31}^2$ and ${sin}^2{\theta }_{23}$ using a variety of samples. Top: The expected sensitivity for 7 years of beam data collection, assuming 3.5 years each in neutrino and antineutrino modes, measured independently using ${\nu }_e$ appearance (blue), ${\nu }_{\mu }$ disappearance (red), and ${\nu }_{\tau }$ appearance (green). Adapted from Ref. [280]. Bottom: The expected sensitivity for the ${\nu }_{\tau }$ appearance channel using 350 $\text{kt}·\text{year}$ of atmospheric exposure

Fig. 39

Sensitivity to the LED model in Refs. [–284] through its impact on the neutrino oscillations expected at DUNE. For comparison, the MINOS sensitivity [285] is also shown

Fig. 40

The 90% CL sensitivity regions for dominant mixings $|U_{\mathit{eN}}{|}^2$ (top left), $|U_{\mu N}{|}^2$ (top right), and $|U_{\tau N}{|}^2$ (bottom) are presented for DUNE ND (black) [287]. The regions are a combination of the sensitivity to HNL decay channels with good detection prospects.These are $N\to \nu ee$, $\nu e\mu$, $\nu \mu \mu$, $\nu {\pi }^0$, $e\pi$, and $\mu \pi$. The study is performed for Majorana neutrinos (solid) and Dirac neutrinos (dashed), assuming no background. The region excluded by experimental constraints (grey/brown) is obtained by combining the results from PS191 [288, 289], peak searches [–294], CHARM [295], NuTeV [296], DELPHI [297], and T2K [298]. The sensitivity for DUNE ND is compared to the predictions of future experiments, SBN [299] (blue), SHiP [300] (red), NA62 [301] (green), MATHUSLA [302] (purple), and the Phase II of FASER [303]. For reference, a band corresponding to the contribution light neutrino masses between 20 and 200 meV in a single generation see-saw type I model is shown (yellow). Larger values of the mixing angles are allowed if an extension to see-saw models is invoked, for instance, in an inverse or extended see-saw scheme