Time variability of the solar neutrino flux especially in the low and intermediate energy sector remains an open question and, if it exists, it is likely to be originated from the magnetic moment transition from active to light sterile neutrinos at times of intense solar activity and magnetic field. We examine the prospects for the SNO+ experiment to address this important issue and to distinguish between the two classes of solar models which are currently identified as corresponding to a high (SSM I) and a low (SSM II) heavy element abundance. We also evaluate the predictions from these two models for the Chlorine experiment event rate in the standard LMA and LMA+Spin Flavour Precession (SFP) scenarios. It is found that after three years of SNO+ data taking, the pep flux measurement will be able to discriminate between the standard LMA and LMA+SFP scenarios, independently of which is the correct solar model. If the LMA rate is measured, SFP with $B_0 \sim 280kG$ for the resonant $Δm^2_{01}$ can be excluded at more than $4σ$. A low rate would signal new physics, excluding all the 90% allowed range of the standard LMA solution at 3$σ$, and a time variability would be a strong signature of the SFP model. The CNO fluxes are the ones for which the two SSM predictions exhibit the largest differences, so their measurement at SNO+ will be important to favour one or the other. The distinction will be clearer after LMA or SFP are confirmed with pep, but still, a CNO measurement at the level of SSM I/LMA will disfavour SSM II at about $3 σ$. We conclude that consistency between future pep and CNO flux measurements at SNO+ and Chlorine would either favour an LMA+SFP scenario or favour SSM II over SSM I.
Due to notoriously small value of the neutrino magnetic moment, the phenomena of neutrino spin flavour precession (SFP) requires very high magnetic field. This makes only a handful of systems suitable to study this phenomena. By the observation of SFP, the Dirac and Majorana nature of neutrinos is expected to be distinguished. In this work, we point out the potential of white dwarf (WD) system in studying the spin-flavour oscillation of neutrinos. From recent analysis, it has been found that young isolated WDs may harbor very strong internal magnetic field, even without exhibiting any surface …
The interaction of neutrino transition magnetic dipole moments with magnetic fields can give rise to the phenomenon of neutrino spin-flavour precession (SFP). For Majorana neutrinos, the combined action of SFP of solar neutrinos and flavour oscillations would manifest itself as a small, yet potentially detectable, flux of electron antineutrinos coming from the Sun. Non-observation of such a flux constrains the product of the neutrino magnetic moment $μ$ and the strength of the solar magnetic field $B$. We derive a simple analytical expression for the expected $\barν_e$ appearance probability i…
最近的太阳和大气nu数据强烈表明需要物理学超越标准模型。我审查的方式调和他们在3-nu振荡。虽然没有暗示的数据,双极大nu混合模型出现的可能性。具有破R宇称的超对称性提供了一种有吸引力的方法来合并它,打开了在高能对撞机(如LHC)或即将到来的长基线或核工厂实验中测试核异常的可能性。除此之外,LSND暗示还需要第四个轻的无菌中微子nus。最简单的是最对称的情况,其中4个中微子中有2个是最大混合的,位于LSND尺度,而其他的则在太阳尺度。nus的亮度,接近最大的大气混合,以及太阳/大气分裂,都是假设的轻子数对称性及其破缺的自然结果。这些基本方案可以在中性电流敏感的太阳和大气中微子实验,如SNO。然而,地下实验还没有证明中微子的质量,因为有很多替代品。例如,变味相互作用可以在解释太阳和大气数据中发挥重要作用,并且可以通过例如μ \to e + γ,μ-e在原子核中的转换进行测试,而不伴随中微子较少的双β衰变。相反,一个短暂的numu可能在解释大气数据中发挥作用。最后,在nus存在的情况下,一个长寿的重nutau可以延迟物质和辐射对宇宙能量密度的贡献变得相等的时间,减少较小尺度上的密度波动,从而节省标准CDM场景,而轻nue,numu和nus将解释太阳和大气数据。
Constraining Ultra-Light Vector Bosons via Solar Neutrino Oscillations: The Gauged $L_μ- L_τ$ Model and Prospects for JUNO and XLZD
Centro de Astrofísica e Gravitação - CENTRA, Departamento de Física, Instituto Superior Técnico - IST, Universidade de Lisboa - UL(里斯本大学技术研究所物理系天体物理学与引力中心)