Jong Hun Jeon

Exclusive B→Mνν¯ (M=π,K,ρ,K∗) decays and leptophobic Z′ model

We consider the exclusive flavor changing neutral current processes B ->M \nu \bar{\nu} (M= \pi, K, \rho, K^*) in the leptophobic Z^\prime model, in which the charged leptons do not couple to the extra Z^\prime boson. We find that these exclusive modes are very effective to constrain the leptophobic Z^\prime model. In the leptophobic Z^\prime model, additional right-handed neutrinos are introduced and they can contribute to the missing energy signal in B ->M + E_missing decays. Through the explicit calculations, we obtain quite stringent bounds on the model parameters, |U_{sb}^{Z^\prime}| \leq 0.29 and |U_{db}^{Z^\prime}| \leq 0.61, from the already existing experimental data. We also briefly discuss an interesting subject of massive right-handed neutrinos, which might be connected with the dark matter problem.

Bs0–B¯s0 mixing and B→πK decays in stringy leptophobic Z′

Abstract We consider a leptophobic Z ′ scenario in a flipped SU(5) grand unified theory obtained from heterotic string theory. We show that the allowed Z ′ mass, flavor conserving and flavor changing couplings of the Z ′ to the down-type quarks are strongly constrained by the mass difference in B s – B ¯ s system and the four branching ratios of B → π K decays. It is shown that even under these constraints large deviations in direct and/or indirect CP asymmetries of B → π K decays from the SM expectations are allowed. Especially it is possible to accommodate the apparent puzzling data in B → π K CP asymmetries.

Bs0–B¯s0 mixing in leptophobic Z′ model

Leptophobic Z^\prime gauge boson appears naturally in many grand unified theories, such as flipped SU(5) or string-inspired E_6 models. This elusive particle easily escapes the direct/indirect detections because it does not couple to charged leptons. However, it can generate flavor changing neutral current at tree level. In this letter, we show that the recently measured mass difference, \Delta m_s, in the B_s^0 -\bar{B}_s^0 system improves the previous bound of flavor changing effective coupling by about one order of magnitude, i.e irrespective of its phase, |U_{sb}^{Z^\prime}| \leq 0.036 for M_{Z^\prime} = 700 GeV, and |U_{sb}^{Z^\prime}| \leq 0.051 for M_{Z^\prime} = 1 TeV.

B_s^0 - \bar{B}_s^0 Mixing in Leptophobic Z^\prime Model

Leptophobic Z^\prime gauge boson appears naturally in many grand unified theories, such as flipped SU(5) or string-inspired E_6 models. This elusive particle easily escapes the direct/indirect detections because it does not couple to charged leptons. However, it can generate flavor changing neutral current at tree level. In this letter, we show that the recently measured mass difference, \Delta m_s, in the B_s^0 -\bar{B}_s^0 system improves the previous bound of flavor changing effective coupling by about one order of magnitude, i.e irrespective of its phase, |U_{sb}^{Z^\prime}| \leq 0.036 for M_{Z^\prime} = 700 GeV, and |U_{sb}^{Z^\prime}| \leq 0.051 for M_{Z^\prime} = 1 TeV.

B0(s) - anti-B0(s) Mixing in Leptophobic Z-prime Model

Leptophobic Z^\prime gauge boson appears naturally in many grand unified theories, such as flipped SU(5) or string-inspired E_6 models. This elusive particle easily escapes the direct/indirect detections because it does not couple to charged leptons. However, it can generate flavor changing neutral current at tree level. In this letter, we show that the recently measured mass difference, \Delta m_s, in the B_s^0 -\bar{B}_s^0 system improves the previous bound of flavor changing effective coupling by about one order of magnitude, i.e irrespective of its phase, |U_{sb}^{Z^\prime}| \leq 0.036 for M_{Z^\prime} = 700 GeV, and |U_{sb}^{Z^\prime}| \leq 0.051 for M_{Z^\prime} = 1 TeV.

Bs0–B¯s0 mixing in leptophobic Z′Z′ model

Leptophobic Z^\prime gauge boson appears naturally in many grand unified theories, such as flipped SU(5) or string-inspired E_6 models. This elusive particle easily escapes the direct/indirect detections because it does not couple to charged leptons. However, it can generate flavor changing neutral current at tree level. In this letter, we show that the recently measured mass difference, \Delta m_s, in the B_s^0 -\bar{B}_s^0 system improves the previous bound of flavor changing effective coupling by about one order of magnitude, i.e irrespective of its phase, |U_{sb}^{Z^\prime}| \leq 0.036 for M_{Z^\prime} = 700 GeV, and |U_{sb}^{Z^\prime}| \leq 0.051 for M_{Z^\prime} = 1 TeV.