Selected topics in heavy flavour physics

Lenz, Alexander

doi:10.1088/0954-3899/41/10/103001

Cited by 12 publications

(9 citation statements)

References 300 publications

(472 reference statements)

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“…The measured value of the dimuon asymmetry by the D0-collaboration [33,34,35,36] seems to be in conflict with the current experimental bounds on a d sl and a s sl , see e.g. the discussion in [122]. An enhanced value of ∆Γ d could solve this experimental discrepancy [123], at the expense of introducing new physics in ∆Γ d and potentially also in a s sl and a d sl .…”

Section: Global χ 2 -Fit Resultsmentioning

confidence: 90%

Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Lenz,

Tetlalmatzi-Xolocotzi

2019

Preprint

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We present a considerably improved analysis of model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons. Our main finding is that contributions of about ±0.1 to the Wilson coefficient of the colour-singlet operator Q 2 of the effective weak Hamiltonian and contributions in the range of ±0.5 (both for real and imaginary part) to Q 1 can currently not be excluded at the 90% C.L.. Effects of such a size can modify the direct experimental extraction of the CKM angle γ by up to 10 • and they could lead to an enhancement of the decay rate difference ∆Γ d of up to a factor of 5 over its SM value -a size that could explain the D0 dimuon asymmetry. Future more precise measurements of the semi-leptonic asymmetries a q sl and the lifetime ratio τ (B s )/τ (B d ) will allow to shrink the bounds on tree-level new physics effects considerably. Due to significant improvements in the precision of the non-perturbative input we update all SM predictions for the mixing obervables in the course of this analysis, obtaining: ∆M s = (18.77 ± 0.86) ps −1 , ∆M d = (0.543 ± 0.029) ps −1 , ∆Γ s = (9.1 ± 1.3) • 10 −2 ps −1 , ∆Γ d = (2.6 ± 0.4) • 10 −3 ps −1 , a s sl = (2.06 ± 0.18) • 10 −5 and a d sl = (−4.73 ± 0.42) • 10 −4 .

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Section: Global χ 2 -Fit Resultsmentioning

confidence: 90%

Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Lenz,

Tetlalmatzi-Xolocotzi

2019

Preprint

View full text Add to dashboard Cite

show abstract

“…The measured value of the dimuon asymmetry by the D0-collaboration [33][34][35][36] seems to be in conflict with the current experimental bounds on a d sl and a s sl , see e.g. the discussion in [138]. An enhanced value of ∆Γ d could solve this experimental discrepancy [139], at the expense of introducing new physics in ∆Γ d and potentially also in a s sl and a d sl .…”

Section: Jhep07(2020)177mentioning

confidence: 90%

Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Lenz

Tetlalmatzi-Xolocotzi

2020

J. High Energ. Phys.

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We present a considerably improved analysis of model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons. Our main finding is that contributions of about ±0.1 to the Wilson coefficient of the colour-singlet operator Q 2 of the effective weak Hamiltonian and contributions in the range of ±0.5 (both for real and imaginary part) to Q 1 can currently not be excluded at the 90% C.L.. Effects of such a size can modify the direct experimental extraction of the CKM angle γ by up to 10 • and they could lead to an enhancement of the decay rate difference ∆Γ d of up to a factor of 5 over its SM value-a size that could explain the D0 dimuon asymmetry. Future more precise measurements of the semi-leptonic asymmetries a q sl and the lifetime ratio τ (B s)/τ (B d) will allow to shrink the bounds on tree-level new physics effects considerably. Due to significant improvements in the precision of the non-perturbative input we update all SM predictions for the mixing obervables in the course of this analysis, obtaining: ∆M s = (18.77 ± 0.86) ps −1 , ∆M d = (0.543 ± 0.029) ps −1 , ∆Γ s = (9.1 ± 1.3) • 10 −2 ps −1 , ∆Γ d = (2.6 ± 0.4) • 10 −3 ps −1 , a s sl = (2.06 ± 0.18) • 10 −5 and a d sl = (−4.73 ± 0.42) • 10 −4 .

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“…Understanding the rate of charm production in b-hadron decays is crucial to validate the HQE that underpins much of the theoretical framework for b physics (see, for example, Ref. [586] for a review). Moreover, such decays are often used as normalization modes for measurements of rarer decays.…”

Section: (B) (A)mentioning

confidence: 99%

Averages of b-hadron, c-hadron, and $$\tau $$ τ -lepton properties as of summer 2016

et al. 2017

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This paper reports world averages of measurements of b-hadron, c-hadron, and τ -lepton properties obtained by the Heavy Flavour Averaging Group using results available before April 2021. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays, and Cabibbo-Kobayashi-Maskawa matrix elements. Selected world averages -continued from previous page. ∆Γ d /Γ d 0.001 ± 0.010 |q d /p d | 1.0010 ± 0.0008 ∆m s 17.765 ± 0.006 ps −1 ∆Γ s +0.084 ± 0.005 ps −1 |q s /p s | 1.0003 ± 0.0014 φ ccs s −0.049 ± 0.019 rad Unitarity-Triangle angle parameters sin2β ≡ sin2φ 1 0.699 ± 0.017 β ≡ φ 1 (22.2 ± 0.7) • −ηS φK 0 S 0.74 +0.11 −0.13 −ηS η K 0 0.63 ± 0.06 −ηS K 0 S K 0 S K 0 S 0.83 ± 0.17 φ s (φφ) −0.073 ± 0.115 ± 0.027 rad S B 0 s →K + K − , C B 0 s →K + K − (0.14 ± 0.03, 0.17 ± 0.03) −ηS J/ψ π 0 0.86 ± 0.14 −ηS D + D − 0.84 ± 0.12 −ηS J/ψ ρ 0 0.66 +0.13 −0.12 +0.09 −0.03(0.343 ± 0.002)% τ parameters, lepton universality, and |V us | g τ /g µ 1.0009 ± 0.0014 g τ /g e 1.0027 ± 0.0014 g µ /g e 1.0019 ± 0.0014* )0 s B ( * )0 s ) = (87.0 ± 1.7)% [34] measured as described in Ref. [35]. The proportions of the various production channels for non-strange B mesons have also been measured [22]. 4.3 b-hadron production fractions at high energy At high energy, all species of weakly decaying b hadrons may be produced, either directly or in strong and electromagnetic decays of excited b hadrons. Before 2010, it was assumed that the fractions of different species in unbiased samples of high-p T b-hadron jets where independent of whether they originated from Z decays, pp collisions at the Tevatron, or pp collisions at the LHC. This hypothesis was plausible under the condition Q 2 Λ 2 QCD , namely, that the square of the momentum transfer to the produced b quarks is large compared with the square of the hadronization energy scale. This hypothesis is correct in the limit p T → ∞, in which the production mechanism of a b hadron is completely described by the fragmentation of the b quark. For finite p T , however, there are interference effects of the production mechanism of the b quark and its hadronization. While formally suppressed by inverse powers of p T , these effects may be sizable, especially when the fragmentation probabilities are small as, e.g., in the case of b baryons. In fact, the available data show that the fractions depend on the kinematics of the produced b hadron. Both CDF and LHCb reported a p T dependence of the fractions, with the fraction of Λ 0 b baryons observed at low p T being enhanced with respect to that seen at LEP at higher p T . In our previous publication [1], we presented two sets of averages, one including only measurements performed at LEP, and another including only measurements performed ...

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Selected topics in heavy flavour physics

Cited by 12 publications

References 300 publications

Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Model-independent bounds on new physics effects in non-leptonic tree-level decays of B-mesons

Averages of b-hadron, c-hadron, and $$\tau $$ τ -lepton properties as of summer 2016

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