Tauonic B decays in the MSSM. arXiv : hep-ph/0409228. YITP : 2005.1.13 Hideo Itoh (Ibaraki univ., KEK) in collaboration with S.Komine(KEK) , Y.Okada(KEK,SOKENDAI). 0: Overview of the physics of the B and SuperB Factory. The current experiments.
arXiv : hep-ph/0409228
YITP : 2005.1.13
Hideo Itoh (Ibaraki univ., KEK)
in collaboration with
The current experiments
Asymmetric B factory experiments(1999～)
KEKB(KEK) : Belle experiment (～340fb-1)
PEPⅡ(SLAC) : BaBar experiment (～250fb-1)
The first purpose of the B factories
Precise test of the CKM picture
for the CPV
We look for deviation from the SM:
Correction from new physics beyond the SM
We need more Luminosity and far precise test.
Processes of the final state including
more than two neutrinos
tauonic B decays : B→Dτν, B→τν
To identify these processes, we have to accumlate
Necessity of the SuperB
Charm physicsMotivation of the SuperB Factory
(Letter of Intent for KEK Super B Factory, hep-ex/0406071)
SuperB Factory : Goal of the luminosity is 50-100 times more
than the current achieved luminosity.
・SuperB is focused on studies for new physics (NP).
・LHC may find NP, but the information from LHC are not
enough to distinguish between NP models.
・SuperB provides much information for the NP models
from following measurements.
- New CP phase
- LFV (τ→μγ, τ→eγ,…)
- Tauonic B decays
These results are useful to
combine with the LHC results.
Two types of the SUSY effects on B physics
1. For the FCNC processes (b→sγ, Bs→μμ, B→φKs…)
2. For the Tauonic B decays (B→Dτν, B→τν)
・Charged Higgs boson can contribute to the decay
amplitude at the tree level in the MSSM.
・At least two neutrinos are present in the final state
in the signal side.
Full-reconstruction is required for
the B decay in the opposite side.
It is difficult to probe the tauonic B decays.
However we may probe the charged Higgs effects on the B physics if we can probe the tauonic B decays.
Full-reconstruction efficiency is 10-3.
So we need more and more luminosity to probe the tauonic B decays.
The branching ratio of the tauonic B decays at the SM
・B→Dτν : 8×10-3
・B→τν : 9×10-5
・B→Dτνis larger branching ratio.
There is no experimental data.
We have not probed B→Dτνat both B factories.
・B→τνis smaller branching ratio due to helicity suppression.
- Upper bound from Belle : 2.9×10-4
- Upper bound from BaBar : 3.3×10-4
These processes are important target of the SuperB Factory.
SUSY correction to yd is induced due to 1-loop diagrams.
(K.S.Babu & C.Kolda, M.Carena, et al)
The b→c(u)τυ processes in the MSSM
for some other processes too.
Ex. BS→μμ(A.Dedes & Pilaftsis, et al)
b→sγ (G.Degrassi & P.Gambino & G.F.Giudice, et al)
We study B￫Dτνand B￫τν in MSSM
・Assume the Minimal Flavor Violation case
・SUSY correction to H±-c (u )-b and H±-τ-νvertex
・Correlation between b￫sγ, Bs￫μ+μ- and tauonic
are induced by SUSY effects through 1-loop diagram.
(A.Dedes & A.Pilaftsis)2: Formalism
Tree level Yukawa couplings have the same structure
as that of the superpotential.
Framework: MSSM with MFV and large tanβ
Minimal Flavor Violation
Squarks have the same flavor structure as one of the quarks.
In other words, the flavor changing source is only the KM matrix.
・Not MFV case
The large deviation from SM is possible generally.
Because there are many flavor mixing parameters.
The large deviation from SM is possible for large tanβ.
tanβ is the ratio of the two vacuum expectation values
of the neutral Higgs.
This assumption comes from mSUGRA, GMSB, AMSB ・・・.
SUSY corrections to the charged Higgs couplings
Charged Higgs coupling including SUSY correction :
“ denotes a diagonal matrix.)
For the correction to the down-type Yukawa coupling
Higgsino contribution becomes too small
in comparison with gluino contribution.
For the correction to the lepton Yukawa coupling
-tion of the parameters in the branching ratio formulas.
SUSY effects are absorbed into
the value of tanβ. I will explain later.
If there are no SUSY corrections (Ex. 2HDM case)
Intuitively, these SUSY corrections become the vertex correction like below.
Also we can see the following results.
There is a correlation between the tauonic B decays at MFV!
・Tree-level charged Higgs effect depends on the following parameters.
・The SUSY corrections to the Yukawa couplings depend on the follow
-ing parameters with tanβ.
The SUSY correction matrix elements
The SUSY correction matrix elements
At above parameter space, the SUSY correction to the
lepton Yukawa coupling becomes sizable in comparison
with the down-type Yukawa’s one.
μ = 400GeV
μ = -400GeV
μ = 400GeV
No SUSY cor. case
No SUSY correction case
Branching ratio for B￫Dτν and B￫τν at tanβ = 50
μ is the higgsino mass parameter.
The SUSY corrections drastically contribute to the branching ratio.
・Vertical error :
・Horizontal error :
・SuperKEKB : 5ab-1
Sensitivity to reach to 11
The correlation itself is the same as the 2HDM,
and so one cannot distinguish them.
The correlation of the two processes as a function of
In MFV, SUSY effect can be absorbed into an effective tanβ.
It is thus interesting to compare it with other experiments.
Receive large correction via SUSY loops.
MSSM with MFV at large tanβ : B￫Dτνand B￫τν
The correlation between Br[B￫Dτν] and Br[B￫τν] in MFV
SUSY loop effect
absorbed into the effective tanβ
Correlation is same as the 2HDM
Important to compare : measurements of Br[B￫Dτν] and Br[B￫τν]
(SuperB Factory )
: measurements of tanβ (LHC )
Ex. ・heavy Higgs direct production
b￫sγ and Bs￫μ+μ- :receive large correction generally
in the same parameter space