Lepton polarization asymmetries in rare semi-tauonic 
                $$ b \rightarrow s $$
                
                    
                        
                            b
                            →
                            s
                        
                    
                
             exclusive decays at FCC-ee

Kamenik, Jernej F.; Monteil, S.; Semkiv, A.; Silva, L. Vale

doi:10.1140/epjc/s10052-017-5272-0

Cited by 29 publications

(14 citation statements)

References 77 publications

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“…About 1000 events with a reconstructedB 0 → K * 0 (892) τ + τ − decay are expected at the FCC-ee, which opens the way to measuring the angular properties of the decay [157] and, therefore, to a much refined characterisation of the potentially underlying new physics. Figure 1.20 displays the reconstructed B 0 mass distribution of simulated SM signal and background events in a sample of 5 × 10 12 Z decays in the CLD detector design.…”

Section: Electroweak Penguins In B-quark Transitionsmentioning

confidence: 99%

FCC-ee: The Lepton Collider

Abada¹,

Abbrescia²,

AbdusSalam³

et al. 2019

Eur. Phys. J. Spec. Top.

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677

511

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Section: Electroweak Penguins In B-quark Transitionsmentioning

confidence: 99%

FCC-ee: The Lepton Collider

Abada¹,

Abbrescia²,

AbdusSalam³

et al. 2019

Eur. Phys. J. Spec. Top.

Self Cite

677

511

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show abstract

“…Furthermore, it would be very important to study b → s τ + τ − transitions, since general EFT considerations suggest that these could be significantly enhanced compared to electron and muon modes [174,242,243]. A sensitivity study [243] has been performed for the FCC-ee collider, which may run at the Z pole and collect of the order of 10 12 Z bosons. In this environment a B → K * τ + τ − branching fraction at the SM value could be measured with a precision of about 5%.…”

Section: Additional Observablesmentioning

confidence: 99%

Review of lepton universality tests in B decays

Bifani

Descotes-Genon

Vidal

et al. 2018

J. Phys. G: Nucl. Part. Phys.

191

188

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Several measurements of tree-and loop-level b-hadron decays performed in the recent years hint at a possible violation of Lepton Universality. This article presents an experimental and theoretical overview of the current status of the field. References 47ii t bDespite its tremendous success in describing all present measurements, the SM can only be regarded as the low-energy, effective, incarnation of a more global theory. For example, the SM cannot account for the matter-antimatter asymmetry currently present in the Universe, it does not provide a Dark Matter candidate and it does not explain its own gauge group structure, the charge assignment of the fermions or the mass hierarchy between the different families. A more global theory that extends the SM at higher energies and shorter distances could provide an answer to some of these questions, which are at the core of modern particle physics.Searches for signs of New Physics (NP) existing beyond the SM are performed in two ways. The first one looks for the direct production of new particles. The key ingredient for this so-called "relativistic path" is the amount of energy available in the collision, which drives the maximum mass range that can be probed. For this reason, the vast majority of the most stringent limits on the mass of NP particles have been obtained at the Large Hadron Collider (LHC) by the ATLAS and CMS experiments, as shown for example in Ref. [1]. The second method, the so-called "quantum path", exploits the presence of virtual states in the decays of SM particles. Due to quantum mechanics, these intermediate states can be much heavier than the initial and final particles, and can affect the rate of specific decay modes as well as their angular distributions. The most evident example is the β decay of the neutron that probes physics at the W -boson scale. Flavour physics, which studies the properties of s-, c-and b-hadrons, has been extremely successful in providing information on the virtual particles involved in the processes examined. A famous example is the observation of CP violation in K decays [2] that could be interpreted as a sign of the existence of three quark families in the SM [3], several years before the discovery of the third generation [4,5]. Similarly, the first observation of the B 0 -B 0 mixing phenomenon [6] revealed that the t-quark mass was much larger than anticipated, eight years before its direct measurement [7,8]. The investigation of the effects induced by virtual particles on SM decays requires very large data samples, since (for a given coupling to NP) the larger the NP scale, the smaller the influence on the process. While the relativistic path probes the scale of potential NP contributions in a direct way through specific signatures, the quantum path provides constraints correlating the scale and the coupling to NP.In the SM, the leptonic parts of the three families of fermions are identical, except for the different masses of the constituent particles. In particular, the photon, the W and the Z bosons couple in ...

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“…[19][20][21] that one can expect an enhancement of up to three orders of magnitude compared to the SM predictions in b → sτ + τ − processes if one aims at explaining the central value of R D ( * ) . So far, among the possible processes, only LHCb searched [27][28][29] and the inclusive B → X s τ + τ − process was assessed in Refs. [26,30].…”

Section: Introductionmentioning

confidence: 99%

Searching for New Physics with b→sτ+τ− Processes

et al. 2018

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In recent years, intriguing hints for the violation of lepton flavor universality (LFU) have been accumulated in semileptonic B decays, both in the charged-current transitions b→cℓ^{-}ν[over ¯]_{ℓ} (i.e., R_{D}, R_{D^{*}}, and R_{J/ψ}) and the neutral-current transitions b→sℓ^{+}ℓ^{-} (i.e., R_{K} and R_{K^{*}}). Hints for LFU violation in R_{D^{(*)}} and R_{J/ψ} point at large deviations from the standard model (SM) in processes involving tau leptons. Moreover, LHCb has reported deviations from the SM expectations in b→sμ^{+}μ^{-} processes as well as in the ratios R_{K} and R_{K^{*}}, which together point at new physics (NP) affecting muons with a high significance. These hints for NP suggest the possibility of huge LFU-violating effects in b→sτ^{+}τ^{-} transitions. In this Letter, we predict the branching ratios of B→Kτ^{+}τ^{-}, B→K^{*}τ^{+}τ^{-}, and B_{s}→ϕτ^{+}τ^{-}, taking into account NP effects in the Wilson coefficients C_{9(^{'})}^{ττ} and C_{10(^{'})}^{ττ}. Assuming a common NP explanation of R_{D}, R_{D^{(*)}}, and R_{J/ψ}, we show that a very large enhancement of b→sτ^{+}τ^{-} processes, of around 3 orders of magnitude compared to the SM, can be expected under fairly general assumptions. We find that the branching ratios of B_{s}→τ^{+}τ^{-}, B_{s}→ϕτ^{+}τ^{-}, and B→K^{(*)}τ^{+}τ^{-} under these assumptions are in the observable range for LHCb and Belle II.

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Lepton polarization asymmetries in rare semi-tauonic $$ b \rightarrow s $$ b → s exclusive decays at FCC-ee

Cited by 29 publications

References 77 publications

FCC-ee: The Lepton Collider

FCC-ee: The Lepton Collider

Review of lepton universality tests in B decays

Searching for New Physics with b→sτ+τ− Processes

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