arXiv subjects

K. Keri Vos

Publications and source records attributed to K. Keri Vos.

59 records · Page 4Linked to original sources

arXiv2017

Towards New Frontiers with $B\toπK$ Decays

Exploring correlations between the CP asymmetries of $B^0_d\toπ^0K_{\rm S}$ following from an isospin relation, we uncover new tensions with the Standard Model in data for neutral $B\toπK$ decays. Should this intriguing picture originate from New Physics, a modified electroweak penguin sector provides a key scenario. It includes models with extra $Z'$ bosons, which offer attractive ways to resolve anomalies in $B\to K^{(*)}\ell^+\ell^-$ measurements. We present a new strategy to reveal the underlying physics, apply it to current $B\toπK$ data, and discuss the excellent prospects for Belle II.

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arXiv2017

CP Violation in Multibody $B$ Decays from QCD Factorization

We test a data-driven approach based on QCD factorization for charmless three-body $B$-decays by confronting it to measurements of CP violation in $B^- \to π^- π^+ π^-$. While some of the needed non-perturbative objects can be directly extracted from data, some others can, so far, only be modelled. Although this approach is currently model dependent, we comment on the perspectives to reduce this model dependence. While our model naturally accommodates the gross features of the Dalitz distribution, it cannot quantitatively explain the details seen in the current experimental data on local CP asymmetries. We comment on possible refinements of our simple model and conclude by briefly discussing a possible extension of the model to large invariant masses, where large local CP asymmetries have been measured.

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arXiv2017

$B^0_s$-$\bar B^0_s$ Oscillations as a New Tool to Explore CP Violation in $D_s^\pm$ Decays

CP violation in $B^0_s$-$\bar B^0_s$ oscillations is expected at the $10^{-5}$ level in the Standard Model but could be enhanced by New Physics. Using $B^0_s\to D_s^-\ell^+ν_\ell$ decays, LHCb has recently reported the new result $(0.39\pm0.33)\times10^{-2}$ of the corresponding observable $a^s_{\rm sl}$. We point out that other current $B$ decay data imply $a^s_{\rm sl} = (0.004 \pm 0.075)\times10^{-2}$. In view of this strong constraint, we propose to use $B^0_s\to D_s^-\ell^+ν_\ell$ and similar flavor-specific decays as a new tool to determine both the production asymmetry between $B^0_s$ and $\bar B^0_s$ mesons, and the CP asymmetry in the subsequent $D^\pm_s$ decays. The former serves as input for analyses of CP violation in $B^0_s$ channels, with significant room for improvement, while the latter offers an exciting laboratory for New Physics.

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arXiv2016

Towards New Frontiers in the Exploration of Charmless Non-Leptonic $B$ Decays

Non-leptonic $B$ decays into charmless final states offer an important laboratory to study CP violation and the dynamics of strong interactions. Particularly interesting are $B^0_s\to K^-K^+$ and $B^0_d\toπ^-π^+$ decays, which are related by the $U$-spin symmetry of strong interactions, and allow for the extraction of CP-violating phases and tests of the Standard Model. The theoretical precision is limited by $U$-spin-breaking corrections and innovative methods are needed in view of the impressive future experimental precision expected in the era of Belle II and the LHCb upgrade. We have recently proposed a novel method to determine the $B_s^0$-$\bar{B}_s^0$ mixing phase $ϕ_s$ from the $B_s^0\to K^-K^+$, $B_d^0\to π^-π^+$ system, where semileptonic $B^0_s\to K^-\ell^+ν_\ell$, $B^0_d\to π^-\ell^+ν_\ell$ decays are a new ingredient and the theoretical situation is very favourable. We discuss this strategy in detail, with a focus on penguin contributions as well as exchange and penguin-annihilation topologies which can be probed by a variety of non-leptonic $B$ decays into charmless final states. We show that a theoretical precision as high as ${\cal O}(0.5^\circ)$ for $ϕ_s$ can be attained in the future, thereby offering unprecedented prospects for the search for new sources of CP violation.

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arXiv2016

New Strategy to Explore CP Violation with $B^0_s\to K^-K^+$

The $U$-spin symmetry provides a powerful tool to extract the angle $γ$ of the Unitarity Triangle and the $B_s^0$-$\bar{B}_s^0$ mixing phase $ϕ_s$ from CP violation in the $B^0_s\to K^-K^+$, $B^0_d\toπ^-π^+$ system. LHCb has obtained first results with uncertainties at the $7^\circ$ level. Due to $U$-spin-breaking corrections, it will be challenging to reduce the uncertainty below ${\cal O}(5^\circ)$ at Belle II and the LHCb upgrade. We propose a new strategy, using $γ$ as input and utilizing $B^0_s\to K^-\ell^+ν_\ell$, $B^0_d\to π^-\ell^+ν_\ell$ decays, which allows an extraction of $ϕ_s$ with a future theoretical precision of up to ${\cal O}(0.5^\circ)$, thereby matching the experimental prospects. Since $B^0_s\to K^-K^+$ is dominated by penguin topologies, new sources of CP violation may be revealed.

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