This work presents a sensitivity study of a reactor liquid scintillator detector to three kinds of dark bosons with masses below 1 MeV, such as dark photons, axion-like particles and light scalar bosons. The JUNO-TAO detector with Taishan nuclear rea
ctor is taken as a reference. With proposed 180 days data taking, the sensitivity to the dark bosons can reach $sim10^{-5}$ 95%C.L. for the optimized signal to background ratio for the electron coupling constant $it{g_X} $ through inverse Compton-like scattering. The background systematic uncertainty presents as the main limiting factor for the further sensitivity improvement. Additionally the differential and the inverse differential cross sections have been derived for all three boson types and their interactions with electrons in liquid scintillator.
The explorations of alternative dark matter (DM) candidates beyond WIMP motivated primordial black holes (PBHs) or sub-GeV DM particle in the Milky Way. Neutrinos from PBH evaporation at the present times play as a novel medium boosting sub-GeV DM an
d leaving signatures in the terrestrial experiments. We explore the boosted DM by the neutrino flux from PBH evaporation (PBH$ u$BDM) so as to connect the macroscopic PBHs to sub-GeV DM particle. We consider this PBH$ u$BDM scenario to interpret the XENON1T keV excess. The projected bounds on the sub-GeV DM-electron scattering cross section and the fraction of DM composed of PBHs $f_{rm PBH}$ are imposed for future experiments.
The active neutrinos can convert into a new exotic fermion $chi$ through coherent neutrino-nucleus scattering $ u Nto chi N$ and thus the $ u-chi$ interaction leads to novel recoil spectrum in the neutrino scattering experiments. We study the general
neutrino interactions by evaluating both the tree-level and loop-level contributions to the coherent elastic neutrino-nucleus scattering (CE$ u$NS). The loop diagrams produce active neutrino elastic scattering process $ u Nto u N$ with the fermion $chi$ inside the loops. The neutrino interaction is illustrated by the framework of a simplified neutrino model in which a new Dirac fermion $chi$ interacts with active neutrinos and a leptophobic vector mediator $Z$. For the $Zqbar{q}$ coupling being vector type and axial-vector type, the CE$ u$NS processes are dominated by the tree-level and loop-level contribution, respectively. We investigate the constraints on the couplings between $Z$ and the new particle $chi$ or the Standard Model quarks by fitting to the COHERENT data. The parameter space with $m_chi$ larger than the maximal energy of incoming neutrinos can also be constrained by including the loop-level contribution. More importantly, the inclusion of loop diagrams can place constraint on axial-vector interaction whose the tree-level process is absent in the coherent neutrino-nucleus scattering.
Recent measurements of the germanium quenching factor deviate significantly from the predictions of the standard Lindhard model for nuclear recoil energies below a keV. This departure may be explained by the Migdal effect in neutron scattering on ger
manium. We show that the Migdal effect on the quenching factor can mimic the signal of a light Z or light scalar mediator in coherent elastic neutrino nucleus scattering experiments with reactor antineutrinos. It is imperative that the quenching factor of nuclei with low recoil energy thresholds be precisely measured close to threshold to avoid such confusion. This will also help in experimental searches of light dark matter.
Neutrino magnetic moment ($ u$MM) is an important property of massive neutrinos. The recent anomalous excess at few keV electronic recoils observed by the Xenon1T collaboration might indicate a $sim 2.2times10^{-11} mu_B$ effective neutrino magnetic
moment ($mu_ u^{eff}$) from solar neutrinos. Therefore, it is essential to carry out the $ u$MM searches at a different experiment to confirm or exclude such hypothesis. We study the feasibility of doing $ u$MM measurement with 4 kton active mass at Jinping neutrino experiment using electron recoil data from both natural and artificial neutrino sources. The sensitivity of $mu_ u^{eff}$ can reach $1.2times10^{-11}mu_B$ at 90% C.L. with 10-year data taking of solar neutrinos. Besides the intrinsic low energy background $^{14}$C in the liquid scintillator, we find the sensitivity to $ u$MM is highly correlated with the systematic uncertainties of $pp$ and $^{85}$Kr. Reducing systematic uncertainties ($pp$ and $^{85}$Kr) and the intrinsic background ($^{14}$C and $^{85}$Kr) can help to improve sensitivities below these levels and reach the region of astrophysical interest. With a 3 mega-Curie (MCi) artificial neutrino source $^{51}$Cr installed at Jinping neutrino detector for 55 days, it could give us a sensitivity to the electron neutrino magnetic moment ($mu_{ u_e}$) with $1.1times10^{-11} mu_B$ at 90% C.L.. With the combination of those two measurements, the flavor structure of the neutrino magnetic moment can be also probed at Jinping.
Nonstandard interactions (NSIs), possible subleading effects originating from new physics beyond the Standard Model, may affect the propagation of neutrinos and eventually contribute to measurements of neutrino oscillations. Besides this, $ mu-tau $
reflection symmetry, naturally predicted by non-Abelian discrete flavor symmetries, has been very successful in explaining the observed leptonic mixing patterns. In this work, we study the combined effect of both. We present an $S_4$ flavor model with $mu-tau$ reflection symmetry realized in both neutrino masses and NSIs. Under this formalism, we perform a detailed study for the upcoming neutrino experiments DUNE and T2HK. Our simulation results show that under the $mu-tau $ reflection symmetry, NSI parameters are further constrained and the mass ordering sensitivity is less affected by the presence of NSIs.
