The type II seesaw model requires that its scalar doublet H and triplet Δ get specific patterns of vacuum expectation values ⟨H⟩∝(0,1)T and ⟨Δ⟩∝(0,0,1)T to accommodate neutrino masses. However, other ...types of minima could also exist in the scalar potential, which may strongly contradict to experimental observations. This paper studies when the minimum at ⟨H⟩∝(0,1)T and ⟨Δ⟩∝(0,0,1)T will be global and finds the necessary and sufficient condition for that, assuming that the lepton number violating term H2Δ in the potential is perturbatively small.
Searching for Z′ bosons at the P2 experiment Dev, P. S. Bhupal; Rodejohann, Werner; Xu, Xun-Jie ...
The journal of high energy physics,
06/2021, Letnik:
2021, Številka:
6
Journal Article
Recenzirano
Odprti dostop
A
bstract
The P2 experiment aims at high-precision measurements of the parity-violating asymmetry in elastic electron-proton and electron-
12
C scatterings with longitudinally polarized electrons. We ...discuss here the sensitivity of P2 to new physics mediated by an additional neutral gauge boson
Z
′ of a new U(1)′ gauge symmetry. If the charge assignment of the U(1)′ is chiral, i.e., left- and right-handed fermions have different charges under U(1)′, additional parity-violation is induced directly. On the other hand, if the U(1)′ has a non-chiral charge assignment, additional parity-violation can be induced via mass or kinetic
Z
-
Z
′ mixing. By comparing the P2 sensitivity to existing constraints, we show that in both cases P2 has discovery potential over a wide range of
Z
′ mass. In particular, for chiral models, the P2 experiment can probe gauge couplings at the order of 10
−
5
when the
Z
′ boson is light, and heavy
Z
′ bosons up to 79 (90) TeV in the proton (
12
C) mode. For non-chiral models with mass mixing, the P2 experiment is sensitive to mass mixing angles smaller than roughly 10
−
4
, depending on model details and gauge coupling magnitude.
We consider a hidden U(1) gauge symmetry under which only the right-handed neutrinos (νR) are charged. The corresponding gauge boson is referred to as the νR-philic Z′. Despite the absence of direct ...gauge couplings to ordinary matter at tree level, loop-induced couplings of the νR-philic Z′ via left-right neutrino mixing can be responsible for its experimental accessibility. An important feature of the νR-philic Z′ is that its couplings to neutrinos are generally much larger than its couplings to charged leptons and quarks, thus providing a particularly interesting scenario for future neutrino experiments such as DUNE to probe. We consider two approaches to probe the νR-philic Z′ at DUNE near detectors via (i) searching for Z′ decay signals, and (ii) precision measurement of elastic neutrino-electron scattering mediated by the Z′ boson. We show that the former will have sensitivity comparable to or better than previous beam dump experiments, while the latter will improve current limits substantially for large neutrino couplings.
A
bstract
The Sommerfeld enhancement plays an important role in dark matter (DM) physics, and can significantly enhance the annihilation cross section of non-relativistic DM particles. In this paper, ...we study the effect of neutrino forces, which are generated by the exchange of a pair of light neutrinos, on the Sommerfeld enhancement. We demonstrate that in certain cases, a neutrino force can cause a significant correction to the Sommerfeld enhancement. Models that can realise DM-neutrino interactions and sizeable Sommerfeld enhancement are also briefly discussed, together with the impacts on DM phenomenology of neutrino forces.
Abstract
Right-handed neutrinos (RHNs) provide a natural portal
to a dark sector accommodating dark matter (DM). In this work, we
consider that the dark sector is connected to the standard model
only ...via RHNs and ask how DM can be produced from RHNs. Our framework
concentrates on a rather simple and generic interaction that couples
RHNs to a pair of dark particles. Depending on whether RHNs are light
or heavy in comparison to the dark sector and also on whether one
or both of them are in the freeze-in/out regime, there are many distinct
scenarios resulting in rather different results. We conduct a comprehensive
and systematic study of all possible scenarios in this paper. For
illustration, we apply our generic results to the type-I seesaw model
with the dark sector extension, addressing whether and when DM in
this model can be in the freeze-in or freeze-out regime. Some observational
consequences in this framework are also discussed.
A
bstract
We revisit the possibility of distinguishing between Dirac and Majorana neutrinos via neutrino-electron elastic scattering in the presence of all possible Lorentz-invariant interactions. ...Defining proper observables, certain regions of the parameter space can only be reached for Dirac neutrinos, but never for Majorana neutrinos, thus providing an al-ternative method to differentiate these two possibilities. We first derive analytically and numerically the most general conditions that would allow to distinguish Dirac from Ma-jorana neutrinos, both in the relativistic and non-relativistic cases. Then, we apply these conditions to data on
ν
μ
-
e
and
ν
¯
e
−
e
scatterings, from the CHARM-II and TEXONO experi-ments, and find that they are consistent with both types of neutrinos. Finally, we comment on future prospects of this kind of tests.
Current data from neutrino oscillation experiments are in good agreement with δ=−π2 and θ23=π4 under the standard parametrization of the mixing matrix. We define the notion of “constrained maximal CP ...violation” (CMCPV) for predicting these features and study their origin in flavor symmetry. We derive the parametrization-independent solution of CMCPV and give a set of equivalent definitions for it. We further present a theorem on how the CMCPV can be realized. This theorem takes the advantage of residual symmetries in neutrino and charged lepton mass matrices, and states that, up to a few minor exceptions, (|δ|,θ23)=(π2,π4) is generated when those symmetries are real. The often considered μ–τ reflection symmetry, as well as specific discrete subgroups of O(3), is a special case of our theorem.
Abstract Solar antineutrinos are absent in the standard solar model prediction. Consequently, solar antineutrino searches emerge as a powerful tool to probe new physics capable of converting ...neutrinos into antineutrinos. In this study, we highlight that neutrino self-interactions, recently gaining considerable attention due to their cosmological and astrophysical implications, can lead to significant solar antineutrino production. We systematically explore various types of four-fermion effective operators and light scalar mediators for neutrino self-interactions. By estimating the energy spectra and event rates of solar antineutrinos at prospective neutrino detectors such as JUNO, Hyper-Kamiokande, and THEIA, we reveal that solar antineutrino searches can impose stringent constraints on neutrino self-interactions and probe the parameter space favored by the Hubble tension.
Neutrino forces in neutrino backgrounds Ghosh, Mitrajyoti; Grossman, Yuval; Tangarife, Walter ...
The journal of high energy physics,
02/2023, Letnik:
2023, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
The Standard Model predicts a long-range force, proportional to
G
F
2
/
r
5
, between fermions due to the exchange of a pair of neutrinos. This quantum force is feeble and has not been ...observed yet. In this paper, we compute this force in the presence of neutrino backgrounds, both for isotropic and directional background neutrinos. We find that for the case of directional background the force can have a 1
/r
dependence and it can be significantly enhanced compared to the vacuum case. In particular, background effects caused by reactor, solar, and supernova neutrinos enhance the force by many orders of magnitude. The enhancement, however, occurs only in the direction parallel to the direction of the background neutrinos. We discuss the experimental prospects of detecting the neutrino force in neutrino backgrounds and find that the effect is close to the available sensitivity of the current fifth force experiments. Yet, the angular spread of the neutrino flux and that of the test masses reduce the strength of this force. The results are encouraging and a detailed experimental study is called for to check if the effect can be probed.
A
bstract
Non-Standard Interactions (NSI) of neutrinos may originate from models in which new particles interact with neutrinos. In scalar extensions of the SM, the typical approach to obtain NSI ...requires Fierz transformations and charged Higgses, which suffer from strong constraints from collider searches or charged lepton flavor violation processes. We propose here an alternative approach to generate NSI, namely via loop processes. We show that such loop-induced NSI from secret neutrino interactions can reach sizes of
O
(0.1 ∼ 1) compared to standard Fermi interaction. This approach can also give rise to neutrino-quark NSI.
PDF
