Two-loop QCD penguin contribution to the width difference in Bs − $$ {\overline{B}}_s $$ mixing

Gerlach, Marvin; Nierste, Ulrich; Shtabovenko, Vladyslav; Steinhauser, Matthias

doi:10.1007/jhep07(2021)043

Cited by 22 publications

(41 citation statements)

References 67 publications

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“…We provide four examples showcasing the features of tapir and discuss the relevant input and output files. tapir already came to use in [62].…”

Section: Discussionmentioning

confidence: 99%

$\texttt{tapir}$: A tool for topologies, amplitudes, partial fraction decomposition and input for reductions

Gerlach,

Herren,

Lang

2022

Preprint

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The demand for precision predictions in the field of high energy physics has dramatically increased over recent years. Experiments conducted at the LHC, as well as precision measurements at the intensity frontier such as Belle II require equally precise theoretical predictions to make full use of the acquired data. To match the experimental precision, two-, three-and, for certain quantities, even higher-loop calculations are required.To facilitate such calculations, computer software automating as many steps as possible is required. Yet, each calculation poses different challenges and thus, a high level of configurability is required. In this context we present tapir: a tool for identification, manipulation and minimization of Feynman integral families. It is designed to integrate in FORM-based toolchains which is common practice in the field. tapir can be used to reduce the complexity of multi-loop problems with cut-filters, topology mapping, partial fraction decomposition and alike.

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“…We provide four examples showcasing the features of tapir and discuss the relevant input and output files. tapir already came to use in [62].…”

Section: Discussionmentioning

confidence: 99%

$\texttt{tapir}$: A tool for topologies, amplitudes, partial fraction decomposition and input for reductions

Gerlach,

Herren,

Lang

2022

Preprint

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“…For a further understanding however it is important to have a precise calculation of higher order corrections in the HQE as well as a complete computation of NNLO-QCD corrections of the leading term, see e.g. [56][57][58]. For a prediction of the CP violation in mixing the contribution from 12 is missing.…”

Section: Discussionmentioning

confidence: 99%

Renormalisation scale setting for D-mixing

Vlahos¹

2021

Proceedings of 10th International Workshop on Charm Physics — PoS(CHARM2020)

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A naive application of the heavy quark expansion (HQE) yields theory estimates for the decay rate of neutral mesons that are four orders of magnitude below the experimental determination. It is well known that this huge suppression results from severe GIM cancellations. We find that this mismatch can be solved by individually choosing the renormalisation scale of the different internal quark contributions. For and hadron lifetimes, as well as for the decay rate difference of neutral mesons the effect of our scale setting procedure lies within the previously quoted theory uncertainties, while we get enlarged theory uncertainties for the semileptonic CP asymmetries in the system.

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“…These matrix elements are multiplied with Wilson coefficients which are calculated in perturbative QCD. The insufficient accuracy of the Wilson coefficients dominates the uncertainty of the SM prediction of ∆Γ q [9][10][11][12][13][14][15], which exceeds the experimental error in Eq. ( 4).…”

Section: Smentioning

confidence: 99%

“…As in Ref. [15] we use the conventional notion of "NLO" and "NNLO" in this paper and treat C 3−6 on the same footing as C 1,2 . With this counting the NLO prediction of Γ s 12 requires the calculation of the yet unknown two-loop contributions with one or two four-quark penguin operators.…”

Section: Smentioning

confidence: 99%

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The width difference in \bbm\ at order $α_s$ and beyond

Gerlach¹,

Nierste²,

Shtabovenko³

et al. 2022

Preprint

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We complete the calculation of the element Γ q 12 of the decay matrix in B q − Bq mixing, q = d, s, to order α s in the leading power of the Heavy Quark Expansion. To this end we compute one-and two-loop contributions involving two four-quark penguin operators. Furthermore, we present two-loop QCD corrections involving a chromomagnetic operator and either a current-current or four-quark penguin operator. Such contributions are of order α 2 s , i.e. next-to-next-to-leading-order. We also present one-loop and two-loop results involving two chromomagnetic operators which are formally of next-to-next-to-leading and next-to-next-to-next-to-leadingorder, respectively. With our new corrections we obtain the Standard-Model prediction ∆Γ s /∆M s = (5.20 ± 0.69) • 10 −3 if Γ s 12 is expressed in terms of the MS b-quark mass, while we find ∆Γ s /∆M s = (4.70 ± 0.96) • 10 −3 instead for the use of the pole mass.

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Two-loop QCD penguin contribution to the width difference in Bs − $$ {\overline{B}}_s $$ mixing

Abstract: We consider two-loop QCD corrections to the element $$ {\Gamma}_{12}^q $$ Γ 12 q of the decay matrix in Bq−$$ {\overline{B}}_q $$ B ¯ q mixing, q = d, s, in the leading power of the Heavy Quark Expansion. The calculated contributions invol… Show more

Cited by 22 publications

References 67 publications

$\texttt{tapir}$: A tool for topologies, amplitudes, partial fraction decomposition and input for reductions

$\texttt{tapir}$: A tool for topologies, amplitudes, partial fraction decomposition and input for reductions

Renormalisation scale setting for D-mixing

The width difference in \bbm\ at order $α_s$ and beyond

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