Search

We thoroughly explore the cosmic gravitational focusing of cosmic neutrino fluid (C$\nu$F) by dark matter (DM) halo using both general relativity for a point source of gravitational potential and Boltzmann equations for continuous overdensities. Derived in the general way for both relativistic and non-relativistic neutrinos, our results show that the effect has fourth power dependence on the neutrino mass and temperature. With nonlinear mass dependence which is different from the cosmic microwave background (CMB) and large scale structure (LSS) observations, the cosmic gravitational focusing can provide an independent cosmological way of measuring the neutrino mass and ordering. We take DESI as an example to illustrate that the projected sensitivity as well as its synergy with existing terrestrial neutrino oscillation experiments and other cosmological observations can significantly improve the neutrino mass measurement., Comment: 41 pages, 6 figures, published JCAP version

Since neutrino oscillation was observed, several experiments have been built to measure its parameters. NO$\nu$A and T2K are two long-baseline experiments dedicated to measuring mainly the mixing angle $\theta_{23}$, the charge-parity conjugation phase $\delta_{\rm CP}$, and the mass ordering. However, there is a tension in current data. The T2K allowed region is almost excluded by the NO$\nu$A result at the $90\%$ confidence level. We propose a non-standard interaction (NSI) in neutrino production to relieve this tension. The NSI is computed through quantum field theory (QFT) formalism, where we derive perturbative analytical formulae considering NSI in the pion decay. Within this new approach, we can alleviate NO$\nu$A and T2K tension for a NSI complex parameters of order $10^{-3}$. We show the new phase has a degeneracy to the Dirac CP phase of the form $\delta_{\rm CP} \pm \phi= 1.5\pi$ being a possible source of violation of charge-parity symmetry.

The neutrino mixing parameters are expected to have RG running effect in the presence of new physics. If the momentum transfers at production and detection mismatch with each other, the oscillation probabilities are generally modified and become dependent on not just the neutrino energy but also the momentum transfer. Even in the limit of vanishing baseline, the transition probability for the appearance channel is interestingly not zero. This would significantly affect the sensitivity of the genuine leptonic Dirac CP phase. We further explore the possibility of combing the long- and short-baseline neutrino experiments to constrain such RG running effect for the purpose of guaranteeing the CP measurement. To simulate the double dependence on the neutrino energy and momentum transfer, we extend the usual GLoBES simulation of fixed baseline experiments and use a two-dimensional $\chi^2$ analysis to obtain sensitivities., Comment: 35 pages, 12 figures, and 1 table. Published version in PRD

We elaborate the possibility of using the atomic radiative emission of neutrino pair (RENP) to probe the neutrino electromagnetic properties, including magnetic and electric dipole moments, charge radius, and anapole. With the typical O(eV) momentum transfer, the atomic RENP is sensitive to not just the tiny neutrino masses but also very light mediators to which the massless photon belongs. The neutrino EM properties introduce extra contribution besides the SM one induced by the heavy W/Z gauge bosons. Since the associated photon spectrum is divided into several sections whose boundaries are determined by the final-state neutrino masses, it is possible to identify the individual neutrino EM form factor elements. Most importantly, scanning the photon spectrum inside the particular section with deviation from the SM prediction once observed allows identification of the neutrino EM form factor type. The RENP provides an ultimate way of disentangling the neutrino EM properties to go beyond the current experimental searches or observations., Comment: 32 pages, 4 figures, matches with the JHEP version

The neutrino magnetic and electric moments are zero at tree level but can arise in radiative corrections. Any deviation from the Standard Model prediction would provide another indication of neutrino-related new physics in addition to the neutrino oscillation and masses. Especially, Dirac and Majorana neutrinos have quite different structures in their electromagnetic moments. Nevertheless, the recoil measurements and astrophysical stellar cooling can only constrain combinations of neutrino magnetic and electric moments with the limitation of not seeing their detailed structures. We propose using the atomic radiative emission of neutrino pair to serve as a unique probe of the neutrino electromagnetic moments with the advantage of not just separating the magnetic and electric moments but also identifying their individual elements. Both searching strategy and projected sensitivities are illustrated in this letter., Comment: 6 pages, 3 figures, match the published version in PLB

We explore the possibility of using the recently proposed THEIA detector to measure the $\bar \nu_\mu \rightarrow \bar \nu_e$ oscillation with neutrinos from a muon decay at rest ($\mu$DAR) source to improve the leptonic CP phase measurement. Due to its intrinsic low-energy beam, this $\mu$THEIA configuration ($\mu$DAR neutrinos at THEIA) is only sensitive to the genuine leptonic CP phase $\delta_D$ and not contaminated by the matter effect. With detailed study of neutrino energy reconstruction and backgrounds at the THEIA detector, we find that the combination with the high-energy DUNE can significantly reduce the CP uncertainty, especially around the maximal CP violation cases $\delta_D = \pm 90^\circ$. Both the $\mu$THEIA-25 with 17kt and $\mu$THEIA-100 with 70kt fiducial volumes are considered. For DUNE + $\mu$THEIA-100, the CP uncertainty can be better than $8^\circ$., Comment: 26 pages, 17 figures, and 1 table

The recent XENON1T excess can be explained by the solar active-sterile neutrino conversion with bound electrons via light mediator. Nevertheless, the atomic effects are usually omitted in the solar neutrino explanations. We systematically establish a second quantization formalism for both bound and ionized electrons to account for the atomic effects. This formalism is of great generality to incorporate various interactions for both neutrino and dark matter scatterings. Our calculation shows that the change in the cross section due to atomic effects can have important impact on the differential cross section. It is necessary to include atomic effects in the low-energy electron recoil signal at dark matter direct detection experiments even for energetic solar neutrinos. With the best-fit values to the XENON1T data, we also project the event rate at PandaX-4T, XENONnT, and LZ experiments., Comment: 22 pages, 10 figure panels, 23 figures

In light of the increasing hints of new physics at the muon $g-2$ and neutrino oscillation experiments, we consider the recently observed tension in the long-baseline neutrino oscillation experiments as a potential indication of Lorentz invariance violation. For this purpose, the latest data from T2K and NO$\nu$A is analysed in presence of non-minimal Lorentz invariance violation. Indeed, we find that isotropic violation in dimensions $D =$ 4, 5 and 6 can alleviate the tension in neutrino oscillation data by 0.4$-$2.4$\sigma$ CL significance, with the isotropic coefficient $\gamma^{(5)}_{\tau \tau} =$ 3.58$\times$10$^{-32}$GeV$^{-1}$ yielding the best fit. At the same time, the anomalous muon $g-2$ result can be reproduced with an additional non-isotropic violation of $d^{zt} =$ -1.7$\times$10$^{-25}$. The analysis highlights the possibility of simultaneous relaxation of experimental tensions with Lorentz invariance violation of mixed nature., Comment: 11 pages, 4 figures, 2 tables; accepted for publication in Physical Review D

We propose a new possibility of using the coherently enhanced neutrino pair emission to probe light-mediator interactions between electron and neutrinos. With typical momentum transfer at the atomic $\mathcal O(1$\,eV) scale, this process is extremely sensitive for the mediator mass range $\mathcal O(10^{-3} \sim 10^4$) eV. The sensitivity on the product of couplings with electron ($g^e$ or $y^e$) and neutrinos ($g^\nu$ or $y^\nu$) can touch down to $|y^e y^\nu| < 10^{-9} \sim 10^{-19}$ for a scalar mediator and $|g^e g^\nu| < 10^{-15} \sim 10^{-26}$ for a vector one, with orders of improvement from the existing constraints., Comment: 13 pages, 4 figures, 1 table

We propose a new scenario of using the dark axion portal at one-loop level to explain the recently observed muon anomalous magnetic moment by the Fermilab Muon g-2 experiment. Both axion/axion-like particle (ALP) and dark photon are involved in the same vertex with photon. Although ALP or dark photon alone cannot explain muon $g-2$, since the former provides only negative contribution while the latter has very much constrained parameter space, dark axion portal can save the situation and significantly extend the allowed parameter space. The observed muon anomalous magnetic moment provides a robust probe of the dark axion portal scenario., Comment: 8 pages, 6 figures, match the EPJC version

We demonstrate how probes of CP-violating observables in Higgs di-tau decays at prospective future lepton colliders could provide a test of weak scale baryogenesis with significant discovery potential. Measurements at the Circular Electron Positron Collider, for example, could exclude a CP phase larger than $2.9^\circ$ ($5.6^\circ$) at 68% (95%) C.L. assuming the Standard Model value for magnitude of the tau lepton Yukawa coupling. Conversely, this sensitivity would allow for a $5\,\sigma$ discovery for 82% of the CP phase range $[0,2\pi)$. The reaches of the Future Circular Collider - ee and International Linear Collider are comparable. As a consequence, future lepton colliders could establish the presence of CP violation required by lepton flavored electroweak baryogenesis with at least $3\,\sigma$ sensitivity. Our results illustrate that Higgs factories are not just precision machines but can also make $\mathcal O(1)$ measurement of the new physics beyond the Standard Model., Comment: 22 pages, 6 figures

The conventional derivation of neutrino oscillation treats neutrino mass eigenstate as plane wave with an overall evolution phase. Nevertheless, due to the intrinsic parity-violating nature of weak interactions, only the left-chiral neutrino can be produced as initial condition. On the other hand, the neutrino mass term connects the left-chiral component to the right-chiral one and unavoidably leads to generation of the later through oscillation. This chiral oscillation has significant consequences on the detection of the cosmological relic neutrinos. The event rate is reduced by a factor of 2 than the conventional prediction., Comment: 5 pages, 1 figure

The recent Xenon1T excess can be explained by solar neutrino scattering with electron via a light mediator, either scalar or vector, in addition to many other explanations from the dark sector. Since only the recoil electron is observable, a keV sterile neutrino instead of an active neutrino can appear in the final state. The sterile neutrino allows pseudoscalar mediator to explain the Xenon1T excess which was thought impossible. In addition, nonzero recoil energy lower bound arises from the sterile neutrino mass, which can be used to testify if the sterile neutrino is massive or not. We also briefly discuss the case of a sterile neutrino final state with light $Z'$ mediator., Comment: 7 pages, 5 figures

The mixing of three active neutrino flavors is parameterized by the unitary PMNS matrix. If there are more than three neutrino flavors and if the extra generations are heavy isosinglets, the effective $3\times 3$ mixing matrix for the three active neutrinos will be non-unitary. We have analyzed the latest T2K and \nova data with the hypothesis of non-unitary mixing of the active neutrinos. We found that the 2019 NO$\nu$A data slightly (at $\sim 1\, \sigma$ C.L.) prefer the non-unitary mixing over unitary mixing. In fact, allowing the non-unitary mixing brings the \nova best-fit point in the $\sin^2\theta_{23}-\delta_{CP}$ plane closer to the T2K best-fit point. The 2019 T2K data, on the other hand, cannot rule out any of the two mixing schemes. A combined analysis of the NO$\nu$A and T2K 2019 data prefers the non-unitary mixing at $1\, \sigma$ C.L.. We derive constraints on the non-unitary mixing parameters using the best-fit to the combined NO$\nu$A and T2K data. These constraints are weaker than previously found. The latest 2020 data from both the experiments prefer non-unitarity over unitary mixing at $1\, \sigma$ C.L. The combined analysis preferes non-unitarity at $2\, \sigma$ C.L. The stronger tension, which exists between the latest 2020 data of the two experiments, also gets reduced with non-unitary analysis., Comment: 30 pages, 19 figures, 3 tables. Results for 2020 data from NOvA and T2K have been included, Accepted in EPJC

We explore the capabilities of the upcoming Deep Underground Neutrino Experiment (DUNE) to measure $\nu_\tau$ charged-current interactions and the associated oscillation probability $P(\nu_\mu \to \nu_\tau)$ at its far detector, concentrating on how such results can be used to probe neutrino properties and interactions. DUNE has the potential to identify significantly more $\nu_\tau$ events than all existing experiments and can use this data sample to nontrivially test the three-massive-neutrinos paradigm by providing complementary measurements to those from the $\nu_e$ appearance and $\nu_\mu$ disappearance channels. We further discuss the sensitivity of the $\nu_\tau$ appearance channel to several hypotheses for the physics that may lurk beyond the three-massive-neutrinos paradigm: a non-unitary lepton mixing matrix, the $3+1$ light neutrinos hypothesis, and the existence of non-standard neutral-current neutrino interactions. Throughout, we also consider the relative benefits of the proposed high-energy tune of the Long-Baseline Neutrino Facility (LBNF) beam-line., Comment: 23 pages, 14 figures, 2 appendices

We show that the minimal 3-3-1 model cannot accommodate the neutrino masses at tree level using present experimental data. Nevertheless, a modified Zee and the Zee-Babu mechanisms for generating neutrino masses at 1-loop and 2-loop, respectively, are automatically implemented in the minimal 3-3-1 model, without introducing new degrees of freedom to the model. We also present a systematic method for finding solutions to the leptonic sector masses and mixing. As a case study, we accommodate the charged and neutral leptons masses and the PMNS matrix in the 1-loop modified Zee mechanism contained in the minimal 3-3-1 model., Comment: 18 pages, 2 figures, 1 table

The effects of Lorentz Invariance Violation(LIV) operators up to dimension 6 in long baseline neutrino experiments are discussed, in specific for DUNE and T2K. A phenomenological Lagrangian is proposed followed by a computation of the effective Hamiltonian of neutrino propagation in matter for mass eigenstates. It is shown that the simplest dimension 4 Lorentz violation parameter can decrease DUNE sensitivity to neutrino mass hierarchy. Also, a $\chi^2$ analysis is performed to obtain the expected long-baseline constraints to the LIV operators up to dimension 6., Comment: 6 pages, 4 figures, 2 tables

We study the capabilities of the short baseline neutrino program at Fermilab to probe the unitarity of the lepton mixing matrix. We find the sensitivity to be slightly better than the current one. Motivated by the future DUNE experiment, we have also analyzed the potential of an extra liquid Argon near detector in the LBNF beamline. Adding such a near detector to the DUNE setup will substantially improve the current sensitivity on non-unitarity. This would help to remove CP degeneracies due to the new complex phase present in the neutrino mixing matrix. We also study the sensitivity of our proposed setup to light sterile neutrinos for various configurations., Comment: 16 pages, 9 figures, 2 tables. Matches with PRD version

We review the current status of neutrino oscillation experiments, mainly focussed on T2(H)K, NO$\nu$A and DUNE. Their capability to probe high energy physics is found in the precision measurement of the CP phase and $\theta_{23}$. In general, neutrino mass models predicts correlations among the mixing angles that can be used to scan and shrink down its parameter space. We updated previous analysis and presents a list of models that contain such structure., Comment: 13 pages, 6 figures, 4 tables. Invited Review for New Physics Landmarks: Dark Matter and Neutrino Masses at Advances in High Energy Physics

We performed a simulation on the DUNE experiment to probe the capability of future neutrino long-baseline experiments' ability to constrain the parameter space of high-energy models by using the correlation between the atmospheric and reactor mixing angles. As an example, we took the Tetrahedral Flavour Symmetry model, which predicts a strong relation between the non-zero value of $\theta_{13}$ and deviation of $\theta_{23}$ from the maximality. We show that in this case, the model can realistically be excluded in more than $3\sigma$ for most of the parameter space. We also study the octant degeneracy at DUNE and its impact on the sensitivity of such models., Comment: 5 pages, 6 figures 1 table

Using the latest global determination of neutrino oscillation parameters from~\cite{deSalas:2017kay} we examine the status of the simplest revamped version of the BMV (Babu-Ma-Valle) model, proposed in~\cite{Morisi:2013qna}. The model predicts a striking correlation between the "poorly determined" atmospheric angle $\theta_{23}$ and CP phase $\delta_{CP}$, leading to either maximal CP violation or none, depending on the preferred $\theta_{23}$ octants. We determine the allowed BMV parameter regions and compare with the general three-neutrino oscillation scenario. We show that in the BMV model the higher octant is possible only at $99\%$ C.L., a stronger rejection than found in the general case. By performing quantitative simulations of forthcoming DUNE and T2HK experiments, using only the four "well-measured" oscillation parameters and the indication for normal mass ordering, we also map out the potential of these experiments to corner the model. The resulting global sensitivities are given in a robust form, that holds irrespective of the true values of the oscillation parameters., Comment: 5 pages, 2 figures

We found an analytical solution for the neutrino mass matrix in the most general case of the Zee model. Using the recent data on the neutrino parameters besides generating neutrino masses at 1-loop level we fit also the masses of the charged leptons and the leptonic mixing matrix. We also show in what conditions the model is not compatible with neutrino data., Comment: 2 figures, 10 pages

Taking into account the current global information on neutrino oscillation parameters we forecast the capabilities of future long baseline experiments such as DUNE and T2HK in settling the atmospheric octant puzzle. We find that a good measurement of the reactor angle $\theta_{13}$ plays a key role in fixing the octant of the atmospheric angle $\theta_{23}$ with such future accelerator neutrino studies., Comment: 5 pages, 4 figures, 1 table. Few changes incorporated, one extra figure added, accepted for PRD rapid communication

We perform realistic simulations of the current and future long baseline experiments such as T2K, NO$\nu$A, DUNE and T2HK in order to determine their ultimate potential in probing neutrino oscillation parameters. We quantify the potential of these experiments to underpin the octant of the atmospheric angle $\theta_{23}$ as well as the value and sign of the CP phase $\delta_{CP}$., Comment: 11 pages, 7 figures, 1 table, Matches with published version in PLB

Here we study the pattern of neutrino oscillations emerging from a previously proposed warped model construction incorporating $\Delta(27)$ flavor symmetry. In addition to a complete description of fermion masses, the model predicts the lepton mixing matrix in terms of two parameters. The good measurement of $\theta_{13}$ makes these two parameters nearly proportional, leading to an approximate one-parameter description of neutrino oscillations. There is a sharp fourfold degenerate correlation between $\delta_{CP}$ and the atmospheric mixing angle $\theta_{23}$, so that maximal $\theta_{23}$ also implies maximal leptonic CP violation. The predicted electron neutrino and anti-neutrino appearance probabilities indicate that the model should be tested at the T2K, NO$\nu$A and DUNE long baseline oscillation experiments., Comment: 12 pages, 15 figures, 1 table, latex

Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase $\delta_{CP}$ of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the "standard" (or "unitary") and "non-unitary" CP phases. We find, under the assumption of non-unitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a $\mu$DAR source for better measurement of $\delta_{CP}$ can partially break the CP degeneracy by probing both $\cos \delta_{CP}$ and $\sin \delta_{CP}$ dependences in the wide spectrum of the $\mu$DAR flux. We also show that the further addition of a near detector to the $\mu$DAR setup can eliminate the degeneracy completely., Comment: 26 pages, latex, 11 figures, matches with PRD