arXiv subjects

Soo-hyeon Nam

Publications and source records attributed to Soo-hyeon Nam.

23 records · Page 2Linked to original sources

arXiv2008

Left-right mixing on leptonic and semileptonic $b\to u$ decays

It has been known that there exists a disagreement emerged between the determination of $|V_{ub}|$ from inclusive $B \to X_u\ellν$ decays and exclusive $B \to π\ellν$ decays. In order to solve the mismatch, we investigate the left-right (LR) mixing effects, denoted by $ξ_u$, in leptonic and semileptonic $b \to u$ decays. We find that the new interactions $(V+A)\times (V-A)$ induced via the LR mixing can explain the mismatch between the values of $|V_{ub}|$ if Re$(ξ_{u})=-(0.14 \pm 0.12)$. Furthermore, we also find that the LR mixing effects can enhance the branching fractions for $B \to τν$ and $B \to ρ\ellν$ decays by 30% and 17%, respectively, while reducing the branching fraction for $B \to γ\ellν$ decays by 18%.

hep-ph↗

arXiv2004

QED corrections to isospin-related decay rates of charged and neutral B mesons

We estimate the isospin-violating QED radiative corrections to the charged-to-neutral ratios of the decay rates for B^+ and B^0 in non-leptonic B meson decays. In particular, these corrections are potentially important for precision measurement of the charged-to-neutral production ratio of B meson in e^+e^- annihilation. We calculate explicitly the QED corrections to the ratios of two different types of decay rates Γ(B^+ \to J/ψK^+)/Γ(B^0 \to J/ψK^0) and Γ(B^+ \to D^+_S \bar{D^0})/Γ(B^0 \to D^+_S D^-) taking into account the form factors of the mesons based on the vector meson dominance model, and compare them with the results obtained for the point-like mesons.

hep-ph↗

arXiv2003

CP asymmetries in penguin-induced B decays in general left-right models

We study CP asymmetries in penguin-induced b -> s\bar{s}s decays in general left-right models without imposing manifest or pseudomanifest left-right symmetry. Using the effective Hamiltonian approach, we evaluate CP asymmetries in B^\pm -> ϕK^{(\ast)\pm} decays as well as mixing induced B meson decays B -> J/ψK_s and B -> ϕK_s decays. Based on recent measurements revealing large CP violation, we show that nonmanifest type model is more favored than manifest or pseudomanifest type.

hep-ph↗

arXiv2002

B\bar{B} Mixing and CP Violation in SU(2)_L \times SU(2)_R \times U(1) Models

We reexamine the mass mixing and CP violation in the B\bar{B} system in general SU(2)_L \times SU(2)_R \times U(1) models related to the recent measurements. The right-handed contributions can be sizable in B\bar{B} mixing and CP asymmetry in B decays for a heavy W^\prime even with a mass about 3 TeV. On the other hand the lower bound on the mass of W^\prime can be taken down to approximately 300 GeV.

hep-ph↗

arXiv1998

Bounds of the mass of Z' and the neutral mixing angles in general SU(2)_L x SU(2)_R x U(1) models

We consider phenomenological constraints on the mass $M_{Z^{\prime}}$ and the two mixing angles $θ_R$ and $ξ$ of the neutral sector in a very general class of $SU(2)_L \times SU(2)_R \times U(1)$ models using electroweak data. We do not make any specific assumptions such as left-right symmetry or the Higgs structure. The analysis of the neutral sector has the advantage that it has relatively fewer parameters compared to the charged sector since the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements in the right-handed sector do not enter into the analysis, hence the number of various possibilities from a big parameter space is reduced. We utilize theoretical considerations on the masses of the gauge particles and the mixing angles. We combine the precision electroweak data from LEP I and the low-energy neutral-current experimental data to constrain the parameters introduced in the model. It turns out that $M_{Z^{\prime}}> 400$ GeV, $-0.0028 <ξ<0.0065$ with little constraint on $θ_R$. In the left-right symmetric theory, $M_{Z^{\prime}}$ should be larger than 900 GeV. With these constraints, we compare the values for $σ(e^+ e^- \to μ^+ μ^-)$, $σ(e^+ e^- \to b\bar{b})$ and $A_{FB}^{\ell}$ at LEP II with experimental values.

hep-ph↗