Identifying and resolving the degeneracies in neutrino oscillation parameters in current experiments
Identifying and resolving the degeneracies in neutrino oscillation parameters in current experiments
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DOI：
10.1103/physrevd.93.013013
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发表时间：
2015-04
期刊：
影响因子：
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通讯作者：
M. Ghosh;P. Ghoshal;S. Goswami;Newton Nath;Sushant K. Raut
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文献类型：
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作者：
M. Ghosh;P. Ghoshal;S. Goswami;Newton Nath;Sushant K. Raut
目前尚不清楚的三个中微子振荡参数是质量等级、混合角θ（23）的八分圆和CP相位δ（CP）。众所周知，层次-δ（CP）和八分体简并的存在影响了这些参数的明确测定。在本文中，我们表明，一个全面的方法来研究剩余的参数退化是在一个广义的层次-θ（23）-δ（CP）退化的形式。对于不同的代表性参数真值，这最好描述为测试（θ（23）-δ（CP））平面中的轮廓。我们发现，错误的层次结构和/或错误的八分体的解决方案可以进一步分为八个不同的解决方案，这取决于它们是否发生错误或正确的值的三角洲（CP）。这八个解不同于原来的八重退化解，并且原则上可以存在，即使theta（13）是已知的。这些多重解，除了影响真实层次和八分圆的确定之外，还影响delta（CP）的准确估计。我们确定这八个不同的简并解决方案可以发生在测试（θ（23）-δ（CP））参数空间，以长基线实验NO NU A运行在中微子模式为例。包含NO nu A反中微子运行消除了出现正确和错误层次结构的错误八分体解决方案。将T2 K数据添加到其中在很大程度上解决了错误的层次-右八分圆解决方案。其余的错误的层次的解决方案，可以删除结合NO nu A + T2 K与大气中微子数据。我们使用ICAL@INO作为原型大气中微子探测器来证明这一点。我们发现，退化可以解决在2西格玛水平的组合数据集，在研究中考虑的真实参数空间。
The three major unknown neutrino oscillation parameters at the present juncture are the mass hierarchy, the octant of the mixing angle theta(23) and the CP phase delta(CP). It is well known that the presence of hierarchy-delta(CP) and octant degeneracies affects the unambiguous determination of these parameters. In this paper, we show that a comprehensive way to study the remaining parameter degeneracies is in the form of a generalized hierarchy -theta(23) - delta(CP) degeneracy. This is best depicted as contours in the test (theta(23) - delta(CP)) plane for different representative true values of parameters. We show that the wrong-hierarchy and/or wrong-octant solutions can be further classified into eight different solutions depending on whether they occur with the wrong or right value of delta(CP). These eight solutions are different from the original eightfold degenerate solutions and can exist, in principle, even if theta(13) is known. These multiple solutions, apart from affecting the determination of the true hierarchy and octant, also affect the accurate estimation of delta(CP). We identify which of these eight different degenerate solutions can occur in the test (theta(23) - delta(CP)) parameter space, taking the long-baseline experiment NO nu A running in the neutrino mode as an example. The inclusion of the NO nu A antineutrino run removes the wrong-octant solutions appearing with both right and wrong hierarchy. Adding T2K data to this resolves the wrong hierarchy-right octant solutions to a large extent. The remaining wrong-hierarchy solutions can be removed by combining NO nu A + T2K with atmospheric neutrino data. We demonstrate this using ICAL@INO as the prototype atmospheric neutrino detector. We find that the degeneracies can be resolved at the 2 sigma level by the combined data set, for the true parameter space considered in the study.