A Mathematica package for calculation of one-loop penguins in FCNC processes

Bednyakov, A. V.; Tanyıldızı, Şükrü Hanif

doi:10.1142/s0129183115500424

“…The UV-divergence vanishes when we sum up over all diagrams and apply the unitarity condition of the leptonic mixing matrix U . We find (using Peng4BSM@LO [34]) that the form factors in the SM extension by heavy neutral leptons (within the SPSS benchmark scenario) are given by…”

Section: Calculation Of the Form Factors For The Clfv Operatorsmentioning

confidence: 98%

“…To calculate the form factors for the cLFV operators within the SPSS from the respective penguin diagrams (cf. figure 3), we use the package Peng4BSM@LO [34]. Peng4BSM@LO is a Mathematica package that calculates the contributions of the form factors of certain effective operators originating from one-loop penguin Feynman diagrams.…”

Section: Calculation Of the Form Factors For The Clfv Operatorsmentioning

confidence: 99%

Searching for charged lepton flavor violation at ep colliders

Antusch

¹

,

Hammad

²

,

Rashed

³

2021

J. High Energ. Phys.

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We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

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“…We find (using Peng4BSM@LO [31]) that the form factors in the SM extension by heavy neutral leptons (within the SPSS benchmark scenario) are given by…”

Section: Calculation Of the Form Factors For The Clfv Operatorsmentioning

confidence: 98%

“…Fig. 3), we use the package Peng4BSM@LO [31]. Peng4BSM@LO is a Mathematica package that calculates the contributions of the form factors of certain effective operators originating from one-loop penguin Feynman diagrams.…”

Section: Calculation Of the Form Factors For The Clfv Operatorsmentioning

confidence: 99%

Searching for charged lepton flavor violation at $ep$ colliders

Antusch,

Hammad,

Rashed

2020

Preprint

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We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

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Dark photon and dark Z mediated B meson decays

Datta

¹

,

Hammad

²

,

Marfatia

³

et al. 2023

J. High Energ. Phys.

7

0

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We study flavor changing neutral current decays of B and K mesons in the dark U(1)D model, with the dark photon/dark Z mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to the differential decay distributions of B → K(∗)ℓ+ℓ−, with ℓ = μ, e, and Bs→ ϕμ+μ−, the allowed parameter space is ruled out by measurements of atomic parity violation, K+→ μ+ + invisible decay, and $$ {B}_s-{\overline{B}}_s $$ B s − B ¯ s mixing, among others. To evade constraints from low energy data, we extend the model to allow for (1) additional invisible ZD decay, (2) a direct vector coupling of ZD to muons, and (3) a direct coupling of ZD to both muons and electrons, with the electron coupling fine-tuned to cancel the ZD coupling to electrons via mixing. We find that only the latter case survives all constraints.

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A Mathematica package for calculation of one-loop penguins in FCNC processes

Cited by 4 publications

References 50 publications

Searching for charged lepton flavor violation at ep colliders

Searching for charged lepton flavor violation at ep colliders

Searching for charged lepton flavor violation at $ep$ colliders

Dark photon and dark Z mediated B meson decays

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