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arXiv 0801.4363hep-ph
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具有Yukawa统一的SUSY大统一理论:使用FCNC过程的go/no-go研究

SUSY GUTs with Yukawa unification: a go/no-go study using FCNC processes

Wolfgang Altmannshofer, Diego Guadagnoli, Stuart Raby, David M. Straub

摘要:

我们解决的可行性,确切汤川统一的背景下,一般超对称大统一我们发现,这种可能性受到了挑战,除非squark频谱被推到自然性所允许的极限之上。这一结论是通过使用电弱观测和夸克的味道改变中性电流(FCNC)过程的全球拟合进行评估。问题主要在于,在考虑了衰变Bs --> mu^+ mu^-的严格CDF上限之后,以及在基本假设下,如B --> Xs l^+ l^-数据所示,b --> s伽马振幅相对于标准模型振幅具有相似的符号,不可能同时容纳底部质量和BR(B --> Xs伽马)。用同样的策略,我们还考虑了将汤川统一放宽为b -τ汤川统一的可能性.我们发现,只要稍微偏离条件tan β ~= 50,当汤川统一是精确的时,上述张力就大大减轻了。我们强调,在该地区的拟合是成功的超对称性频谱的最轻的部分基本上是固定的b -τ统一的要求和应用FCNC约束。因此,一旦LHC启动,它很容易被证伪。

英文摘要:

We address the viability of exact Yukawa unification in the context of general SUSY GUTs with universal soft-breaking sfermion and gaugino mass terms at the GUT scale. We find that this possibility is challenged, unless the squark spectrum is pushed well above the limits allowed by naturalness. This conclusion is assessed through a global fit using electroweak observables and quark flavour-changing neutral current (FCNC) processes. The problem is mostly the impossibility of accommodating simultaneously the bottom mass and the BR(B --> Xs gamma), after the stringent CDF upper bound on the decay Bs --> mu^+ mu^- is taken into account, and under the basic assumption that the b --> s gamma amplitude have like sign with respect to the Standard Model one, as indicated by the B --> Xs l^+ l^- data. With the same strategy, we also consider the possibility of relaxing Yukawa unification to b - tau Yukawa unification. We find that with small departures from the condition tan beta ~= 50, holding when Yukawa unification is exact, the mentioned tension is substantially relieved. We emphasize that in the region where fits are successful the lightest part of the SUSY spectrum is basically fixed by the requirements of b - tau unification and the applied FCNC constraints. As such, it is easily falsifiable once the LHC turns on.

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