B physics constraints on a flavor symmetric scalar model to account for the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mi>t</mml:mi><mml:mover accent="true"><mml:mi>t</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math> asymmetry and Wjj excess at CDF

Abstract

Recently Nelson et al. proposed an interesting flavor symmetric model to\naccount for the top quark forward-backward asymmetry and the dijet anomaly at\nCDF simultaneously with just three parameters: a coupling constant of order\none, and two scalar masses of 160 GeV and 220 GeV. However these fiducial\nvalues of the parameters lead to the branching ratio of a almost pure penguin B\n-&gt; pi K decay about one hundred times larger than the experimental results.\nConsider also the precision electroweak constraints, the scalar masses should\nbe at least around 500 GeV. Actually with the coupling constant larger than\none, it is impossible to explain either of the two CDF measurements\nconsistently in this model. But one may raise the charged scalar mass to, for\nexample, 250 GeV and reduce the coupling strength to 0.6 to meet the B physics\nconstraints. With this parameter set, the Wjj cross section is found to be in\nthe right range. But due to the scalar mass splitting, its correction to\nT-parameter is about 3 sigma away from the precision electroweak constraints.\nIn addition, the top quark forward-backward asymmetry should be well below 0.1\nwith this small coupling constant.\n