arXiv subjects

V. Poghosyan

Publications and source records attributed to V. Poghosyan.

5 recordsLinked to original sources

arXiv2006

Estimate of BR(B -> X_s gamma) at O(alpha_s^2)

Combining our results for various O(alpha_s^2) corrections to the weak radiative B-meson decay, we are able to present the first estimate of the branching ratio at the next-to-next-to-leading order in QCD. We find BR(B -> X_s gamma) = (3.15 +_ 0.23) x 10^-4 for E_gamma > 1.6 GeV in the B-meson rest frame. The four types of uncertainties: non-perturbative (5%), parametric (3%), higher-order (3%) and m_c-interpolation ambiguity (3%) have been added in quadrature to obtain the total error.

hep-ph↗

arXiv2006

NNLL QCD Contribution of the Electromagnetic Dipole Operator to Gamma(anti-B -> X(s) gamma)

We present an independent calculation of that part of the O(α_s^2) contribution to the decay width Γ(\bar B -> X_s γ) which arises from the self-interference term of the electromagnetic dipole operator O_7. Using a different method, we find complete agreement with a previous calculation. This NNLL contribution is an important ingredient for the complete NNLL prediction of Γ(\bar B -> X_s γ) which will resolve the charm quark mass ambiguity appearing at NLL accuracy.

hep-ph↗

arXiv2005

Towards the NNLL precision in $\bar B \to X_s γ$

The present NLL prediction for the decay rate of the rare inclusive process $\bar B \to X_s γ$ has a large uncertainty due to the charm mass renormalization scheme ambiguity. We estimate that this uncertainty will be reduced by a factor of 2 at the NNLL level. This is a strong motivation for the on-going NNLL calculation, which will thus significantly increase the sensitivity of the observable $\bar B \to X_s γ$ to possible new degrees of freedom beyond the SM. We also give a brief status report of the NNLL calculation.

hep-ph↗

arXiv2005

Reduction of Charm Quark Mass Scheme Dependence in $\bar B \to X_s γ$ at the NNLL Level

The uncertainty of the theoretical prediction of the $\bar B \to X_s γ$ branching ratio at NLL level is dominated by the charm mass renormalization scheme ambiguity. In this paper we calculate those NNLL terms which are related to the renormalization of $m_c$, in order to get an estimate of the corresponding uncertainty at the NNLL level. We find that these terms significantly reduce (by typically a factor of two) the error on ${BR}(\bar B \to X_s γ)$ induced by the definition of $m_c$. Taking into account the experimental accuracy of around 10% and the future prospects of the $B$ factories, we conclude that a NNLL calculation would increase the sensitivity of the observable $\bar B \to X_s γ$ to possible new degrees of freedom beyond the SM significantly.

hep-ph↗

arXiv2004

Complete bremsstrahlung corrections to the forward-backward asymmetries in $b\to X_s\ell^+\ell^-$

In a recent paper we presented a calculation of NNLL virtual corrections to the forward-backward asymmetries in $b\to X_s\ell^+\ell^-$ decay. That result does not include bremsstrahlung corrections which are free from infrared and collinear singularities. In the present paper we include the remaining ${\cal O}(α_s)$ bremsstrahlung corrections to the forward-backward asymmetries in $b\to X_s\ell^+\ell^-$ decay. The numerical effect of the calculated contributions is found to be below 1%.

hep-ph↗