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CP VIOLATION in b → s l + l - Transition
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Direct CP-Violation CP non-conservation shows up as a rate difference between two processes that are the CP conjugates of one-another. How can such a rate difference appear?
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This shows that the effect will vanish if the two coupling constants can be made relatively real. And also if strong phase be zero.
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CP violation in SM. 4 parameters : Euler angles: ½ n(n-1)=3 Complex Phase: ½ (n-1)(n-2)=1 Unitarity and Properties of CKM
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physics beyond the Standard Model will have, in general, possible additional CP-violating parameters. Any further fields, such as any additional Higgs fields, can introduce further CP-violating couplings. Such effects may then enter into B decay physics.
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FCNC IN b s(d) TRANSITION : 1. As a test of SM and beyond SM 1. As a test of SM and beyond SM 2. As a tool to Det. CKM elements 2. As a tool to Det. CKM elements such as V tq (q=d,s,b), V ub such as V tq (q=d,s,b), V ub 3. CP- Violation 3. CP- Violation
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V ub V us * + V tb V ts * + V cb V cs * = 0 Using unitary condition of CKM matrix and Using unitary condition of CKM matrix and neglecting |V ub V * us | in comparison to |V tb V * ts | and |V cb V * cs | Indicate that such decay involves only CP –Violation in this channel is suppressed by SM. b → s l + l -
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Beyond the SM The possibility of CP violation the b → s transition has been studied in supersymmetry by [Kruger, et al]. The SM with fourth generation [Arhrib et al]. In another study, this has been studied with the addition of CP odd phases to Wilson coefficients [Aliev, et al].
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The formalism Using general form of 4-Fermi interactions in SM.
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Minimal Extension of the SM: We extend the matrix element of the b → s l+ l- where C 9 b → s l+ l- where C 9 get a new weak phase. Λ new Can be parameterized as :
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Using the expression of the matrix element and neglecting the s-quark mass (ms), we obtain the expression for the differential decay rate as:
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is the velocity of the final lepton & ∆ is expression in terms of masses, Wilson coefficients. ∆ is expression in terms of masses, Wilson coefficients.
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CP-Violation asymmetry CP-Violation differential decay width asymmetry is defined:
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The differential decay width for the CP conjugated process can be obtain by making the replacements:
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CP-asymmetry is evaluated to be Since for any allowed region of s, << , So, we can ignore the term proportional to in the dominator of equation :
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Numerical analysis we examine the dependence of A CP on new.. A CP depends on both magnitude and phase of new. b → s l + l - The first measurement of the b → s l + l - decay reported by BELLE help us to get an idea about magnitude of new. We assume that:
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In order to eliminate the s dependence, instead of CP asymmetry in the differential decay width, we study CP asymmetry in the total decay width by doing numerical integration over s in A CP (s) equation:
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The figure depicts that A CP is sensitive to the new weak phase and can reach about 4.5% which is quite measurable at future colliders such as LHCb, BTeV, ATLAS CMS or ILC.
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b → s l+ l- In conclusion, this study has presented the CP asymmetry in the b → s l+ l- transition in the minimal extension of the standard model where C 9 eff received extra weak phase new due to the new physics effects. We imposed 10% of uncertainty to the SM branching ratio of the b → s l+ l- b → s l+ l- transition and obtained the bound on a new parameter new. Our predictive model showed that the CP-violation asymmetry could reach to the order of 4.5% which was not only entirely measurable in experiments, but also indicated the new physics effects, since in the SM, this CP asymmetry is near zero.
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