摘要：The neutrinoless double-beta (0ν2β) decay is currently the only feasible process in particle and nuclear physics to probe whether massive neutrinos are the Majorana fermions. If they are of the Majorana nature and have a normal mass ordering, the eﬀective neutrino mass term mee of a 0ν2β decay may suﬀer signiﬁcant cancellations among its three components and thus sink into a decline,resulting in a “well” in the three-dimensional graph of |mee| against the smallest neutrino mass m1 and the relevant Majorana phase ρ. We present a new and complete analytical understanding of the ﬁne issues inside such a well, and identify a novel threshold of |mee| in terms ofthe neutrino masses and ﬂavor mixing angles: |mee|∗ = m3 sin2 θ13 in connection with tan θ12 = m1/m2 and ρ = π. This threshold point, which links the local minimum and maximum of |mee|, can be used to signify observability or sensitivity of the future 0ν2β-decay experiments. Given current neutrino oscillation data, the possibility of |mee| < |mee|∗ is found to be very small.
摘要：We take the JUNO experiment as an example to explore nuclearites in the future large liquid scintillator detector. Comparing to the previous calculations, the visible energy of nuclearites across the liquid scintillator will be reestimated for the liquid scintillator based detector. Then the JUNO sensitivities to the nuclearite flux are presented. It is found that the JUNO projected sensitivities can be better than 7.7×10−17cm−2s−1sr−1 for the nuclearite mass 1015 GeV ≤ M ≤ 1024 GeV and initial velocity 10−4 ≤ β0 ≤ 10−1 with a 20 year running. Note that the JUNO will give the most stringent limits for downgoing nuclearites with 1.6 × 1013 GeV ≤ M ≤ 4.0 × 1015 GeV and a typical galactic velocity β0 = 10−3.
摘要：Aside from its primary purpose of shedding light on the mass hierarchy (MH) using reactor antineutrinos,the JUNO experiment in Jiangmen (China) will also contribute to study neutrinos from non-reactor sources. In this poster we review JUNO’s goals in the realms of supernova, atmospheric,solar and geo-neutrinos; present the related experimental issues and provide the current estimates of its potential. For a typical galactic SN at a distance of 10 kpc, JUNO will record about 5000 events from inverse beta decay, 2000 events from elastic neutrino-proton scattering, 300 events from neutrino-electron scattering, and the charged current and neutral current interactions on the 12C nuclei. For atmospheric neutrinos, JUNO should be able to detect ne and nm charged current events. Optimistically, a determination of the MH could be achieved at the 1.8s (2.6s ) level after 10 (20) years of data taking. JUNO will also study solar neutrinos from 7Be and 8B, at low (≈1 MeV) and higher energies respectively, to improve our understanding of the matter effects on the oscillation mechanism and of the solar metallicity. Challenges come primarily from the radioactive and cosmogenic backgrounds: the expected performance for two benchmark scintillator radio-purities, are shown. The flux of geo-neutrinos gives us an insight on the Earth composition and formation. We will show how the increased sample size given by JUNO’s large sensitive mass of 20 KTon liquid scintillator will provide data to answer to several geological questions among which the U/Th ratio and mantle measurements
摘要：We update the cosmological parameter estimation for three non-vanilla models by a joint analysis of CCCP X-ray cluster, the newly released Planck CMB data as well as some external data sets, such as baryon acoustic oscillation measurements from the 6dFGS, SDSS DR7 and BOSS DR9 surveys, and Hubble Space Telescope H0 measurement. First of all, we nd that X-ray cluster data sets strongly favor a non-zero summed neutrino mass at more than 3 con dence level in these non-vanilla models. And then, we reveal some tensions between X-ray cluster and Planck data in some cosmological parameters. For the matter power spectrum amplitude 8, X-ray cluster data favor a lower value compared with Planck. Because P of the strong 8 m degeneracy, this tension could beyond 2 con dence level when the P summed neutrino mass m is allowed to vary. For the CMB lensing amplitude AL, the addition of X-ray cluster data results in a 3 deviation from the vanilla model. Furthermore, Planck+X-ray data prefer a large Hubble constant and phantom-like dark energy equation of state, which are in 2 tension with those from WMAP7+X-ray data. Finally, we nd that these tensions/descrepencies could be relaxed in some sense by adding a 9% systematic shift in the cluster mass functions.
摘要：The three active light neutrinos are used to explain the neutrino oscillations.The inherently bi-large mixing neutrino mass matrix and the Fritzsch type,bi-small mixing charged lepton mass matrix are assumed. By requiring the maximal #23;μ −#23;#28; mixing for the atmospheric neutrino problem and the mass-squared difference approperiate for the almost maximal mixing solution to the solar neutrino problem, the following quantities are predicted: the #23;e−#23;μ mixing, Ve3, CP violation in neutrino oscillations, and the effective electron-neutrino mass relevant to neutrinoless double beta decays.
摘要：If the tau neutrino is as heavy as 10 MeV which may have certain astrophysical implications, the neutrino mass pattern is studied so as to accommodate the new oscillation observations. It predicts that the electron neutrino has Marjorana mass around 0.05 eV. A supersymmetric model is described to realize the above scenario.
摘要：The maximal U(1)LU(1)LU(1)_L supersymmetric inverse seesaw mechanism (MLSIS) provides a natural way to relate asymmetric dark matter (ADM) with neutrino physics. In this paper we point out that MLSIS is a natural outcome if one dynamically realizes the in
摘要：In order to have massive neutrinos, the right-handed neutrino/sneutrino superfield (N ) need to be introduced in supersymmetry. In the framework of NMSSM (the MSSM with a singlet S) such an extension will dynamically lead to a TeV-scale Majorana mass for
摘要：The top and bottom seesaw model, which extends the top seesaw in order to accommodate a 125 GeV Higgs boson, predicts vector-like top/bottom partners and these partners can be bounded to form several neutral and charged singlet composite scalars by some n
摘要：The dimension-six CP-violating SU_L(2)\times U_Y(1) invariant operators involving the tau lepton are studied. The constraints from the available experimental data on tau dipole moments are derived. Under the current constraints, the induced CP-violating e
摘要：We discuss the prospects of a very long baseline neutrino oscillation experiment from HIPA to Beijing. The current understanding of neutrino oscillations, both theoretically and experimentally, are summarized. The figure of merits for interested physics m
摘要：We examine the prospects of making a joint analysis of neutrino oscillation at two baselines with neutrino superbeams. Assuming narrow band superbeams and a 100 kt water Cerenkov calorimeter, we calculate the event rates and sensitivities to the matter ef
摘要：Considering the mass splitting between three active neutrinos, we represent the new constraints on the sum of neutrino mass ∑mν by updating the anisotropic analysis of Baryon Acoustic Oscillation (BAO) scale in the CMASS and LOWZ galaxy samples from Data Release 12 of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS DR12). Combining the BAO data of 6dFGS, MGS, LOWZ and CMASS with Planck~2015 data of temperature anisotropy and polarizations of Cosmic Microwave Background (CMB), we find that the 95% C.L. upper bounds on ∑mν refer to ∑mν,NH<0.18 eV for normal hierarchy (NH), ∑mν,IH<0.20 eV for inverted hierarchy (IH) and ∑mν,DH<0.15 eV for degenerate hierarchy (DH) respectively, and the normal hierarchy is slightly preferred than the inverted one (Δχ2≡χ2NH−χ2IH≃−3.4). In addition, the additional relativistic degrees of freedom and massive sterile neutrinos are neither favored at present.
摘要：Behind the observed pattern of lepton flavor mixing is a partial or approximate mu-tau flavor symmetry --- a milestone on our road to the true origin of neutrino masses and flavor structures. In this review article we first describe the features of mu-tau permutation and reflection symmetries, and then explore their various consequences on model building and neutrino phenomenology. We pay particular attention to soft mu-tau symmetry breaking, which is crucial for our deeper understanding of the fine effects of flavor mixing and CP violation.
摘要：We present an evaluation of the background induced by�41Am-13C neutron calibration sources in the Daya Bay reactor neutrino experiment. As a significant background for electron-antineutrino detection at 0.26�.12 per detector per day on average, it has been estimated by a Monte Carlo simulation that was benchmarked by a special calibration data set. This dedicated data set also provided the energy spectrum of the background.
摘要：In this letter, we put forward a special neutrino mass matrix which is invariant under a modified Friedberg-Lee (FL) transformation νe→νe−2θ and νμ,τ→νμ,τ+θ with θ being a space-time independent element of the Grassmann algebra. Compared to the original FL symmetry (with the transformation νe,μ,τ→νe,μ,τ+θ) which results in the TM2 neutrino mixing, the modified FL symmetry will lead us to the TM1 mixing which has a better agreement with the experimental results. While the original FL symmetry has to be broken in order to produce a realistic neutrino mass spectrum, the modified FL symmetry is allowed to remain intact and give us a vanishing m1. A combination of the FL symmetry with the μ-τ reflection symmetry is also discussed.
摘要：The latest results from atmospheric and accelerator neutrino experiments indicate that the normal neutrino mass ordering m1
摘要：It remains to be determined experimentally if massive neutrinos are Majorana or Dirac particles. In this connection, it has been recently suggested that the detection of cosmic neutrino background of left-handed neutrinos νL and right-handed antineutrinos ν¯¯¯R in future experiments of neutrino capture on beta-decaying nuclei (e.g., νe+3H→3He+e− for the PTOLEMY experiment) is likely to distinguish between Majorana and Dirac neutrinos, since the capture rate is twice larger in the former case. In this paper, we investigate the possible impact of right-handed neutrinos on the capture rate, assuming that massive neutrinos are Dirac particles and both right-handed neutrinos νR and left-handed antineutrinos ν¯¯¯L can be efficiently produced in the early Universe. It turns out that the capture rate can be enhanced at most by 28% due to the presence of relic νR and ν¯¯¯L with a total number density of 95 cm−3, which should be compared to the number density 336 cm−3 of cosmic neutrino background. The enhancement has actually been limited by the latest cosmological and astrophysical bounds on the effective number of neutrino generations Neff=3.14+0.44−0.43 at the 95% confidence level. For illustration, two possible scenarios have been proposed for thermal production of right-handed neutrinos in the early Universe.
摘要：In light of the latest neutrino oscillation data, we revisit the minimal scenario of type-I seesaw model, in which only two heavy right-handed Majorana neutrinos are introduced to account for both tiny neutrino masses and the baryon number asymmetry in our Universe. In this framework, we carry out a systematic study of the Frampton-Glashow-Yanagida ansatz by taking into account the renormalization-group running of neutrino mixing parameters and the flavor effects in leptogenesis. We demonstrate that the normal neutrino mass ordering is disfavored even in the minimal supersymmetric standard model with a large value of tanβ, for which the running effects could be significant. Furthermore, it is pointed out that the original scenario with a hierarchical mass spectrum of heavy Majorana neutrinos contradicts with the upper bound derived from a naturalness criterion, and the resonant mechanism with nearly-degenerate heavy Majorana neutrinos can be a possible way out.
摘要：Providing an early warning of galactic supernova explosions from neutrino signals is important in studying supernova dynamics and neutrino physics. A dedicated supernova trigger system has been designed and installed in the data acquisition system at Daya Bay and integrated into the worldwide Supernova Early Warning System (SNEWS). Daya Bay's unique feature of eight identically-designed detectors deployed in three separate experimental halls makes the trigger system naturally robust against cosmogenic backgrounds, enabling a prompt analysis of online triggers and a tight control of the false-alert rate. The trigger system is estimated to be fully sensitive to 1987A-type supernova bursts throughout most of the Milky Way. The significant gain in sensitivity of the eight-detector configuration over a mass-equivalent single detector is also estimated. The experience of this online trigger system is applicable to future projects with spatially distributed detectors.