On the angular distribution of Λb → Λ(→ N π)τ +τ − decay

Das, Diganta

doi:10.1007/jhep07(2018)063

Cited by 23 publications

(15 citation statements)

References 60 publications

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“…Our work extends earlier studies of the threebody decay Λ 0 b → Λ + c −ν [31], and of the four-body decay Λ 0 b → Λ + c (→ Λ 0 π + ) −ν [32,33]. Our analysis follows closely previous works on the flavour-changing neutral-current decay Λ 0 b → Λ 0 (→ pπ − ) + − [34][35][36], which has a qualitatively similar angular distribution. The LHCb experiment can only reconstruct the decay mode at hand by reconstructing Λ 0 → pπ − decays, which correspond to 64% of the Λ 0 branching fraction [37].…”

Section: Introductionsupporting

confidence: 86%

Angular analysis of Λb→ Λc(→ Λπ) ℓ$$ \overline{\nu} $$

Böer

Kokulu

Toelstede

et al. 2019

J. High Energ. Phys.

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We revisit the decay Λ 0 b → Λ + c −ν (= e, µ, τ) with a subsequent two-body decay Λ + c → Λ 0 π + in the Standard Model and in generic New Physics models. The decay's joint four-differential angular distribution can be expressed in terms of ten angular observables, assuming negligible polarization of the initial Λ b state. We present compact analytical results for all angular observables, which enables us to discuss their possible New Physics reach. We find that the decay at hand probes more and complementary independent combinations of Wilson coefficients compared to its mesonic counter parts B → D (*) −ν. Our result for the angular distribution disagrees with some of the results on scalar-vector interference terms in the literature. We provide numerical estimates for all angular observables based on lattice QCD results for the Λ b → Λ c form factors and account for a recent measurement of the parity-violating parameter in Λ + c → Λ 0 π + decays by BESIII. A numerical implementation of our results is made publicly available as part of the EOS software.

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Section: Introductionsupporting

confidence: 86%

Angular analysis of Λb→ Λc(→ Λπ) ℓ$$ \overline{\nu} $$

Böer

Kokulu

Toelstede

et al. 2019

J. High Energ. Phys.

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“…For instance, the Λ b → Λ(1116)(→ N π)µ + µ − has been investigated theoretically in refs. [30][31][32][33][34][35] and measured by the LHCb collaboration in refs. [36,37] for both the differential decay rate and the angular observables.…”

Section: Jhep06(2019)136 Introductionmentioning

confidence: 99%

Angular analysis of the rare decay $$ {\Lambda}_b\to \Lambda (1520)\left(\to N\overline{K}\right){\ell}^{+}{\ell}^{-} $$

Descotes-Genon

Novoa-Brunet

2019

J. High Energ. Phys.

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We study the differential decay rate for the rare decay Λ b → Λ(1520)(→ NK) + − where is a light lepton and NK = pK − , nK 0 , as this decay mode can provide new and complementary constraints on the Wilson coefficients in b → s + − transitions compared to other modes. We provide a determination of the complete angular distribution, assuming unpolarised Λ b baryons and neglecting the lepton mass. The resulting angular observables are expressed in terms of helicity amplitudes involving hadronic form factors within the Standard Model and New Physics models with chirality-flipped operators. We study these observables at low and large Λ recoils, using effective theories to determine relations among the hadronic form factors involved. As there is currently no determination of the form factors available from lattice simulations or light-cone sum rules, we perform a first illustration of the sensitivity of some observables to New Physics contributions using hadronic inputs from quark models.

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“…Additionally, in the SM there is also a dipole operator O 7 that contributes to the b → s transition. The long-distance part of the decay is encoded in the b → transition matrix elements (see [22] for definitions) which are parametrized in terms of six q 2 dependent form factors f V t,0,⊥ , f A t,0,⊥ [23]. For our numerical analysis the form factors are taken from calculations in lattice QCD [24].…”

Section: Effective Hamiltonianmentioning

confidence: 99%

“…In the literature, instead of the hadronic helicity amplitudes, transversity amplitudes A i ⊥( ) 1 , A i ⊥( ) 0 and A S⊥( ) , A P⊥( ) are often used. Following [22] the expressions of the transversity amplitudes are collected in Appendix A.…”

Section: Effective Hamiltonianmentioning

confidence: 99%

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Lepton flavor violating $$\Lambda _b\rightarrow \Lambda \ell _1\ell _2$$ decay

Das

2019

Eur. Phys. J. C

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Inspired by the recent hints of lepton flavor universality violation in b → s and b → c ν transitions, we study lepton flavor violating exclusive b → + 1 − 2 (1 = 2) decay, which is forbidden in the Standard Model. Starting from a general effective Hamiltonian for a b → s + 1 − 2 transition that includes vector and axial-vector operators, and scalar and pseudo-scalar operators, we derive a twofold decay distribution of b → + 1 − 2. The distribution helps us to construct the differential branching ratio and the lepton-side forward-backward asymmetry, which are studied in a vector leptoquark model. The parameter space of the vector leptoquark model is constrained by low energy observables.

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On the angular distribution of Λb → Λ(→ N π)τ +τ − decay

Cited by 23 publications

References 60 publications

Angular analysis of Λb→ Λc(→ Λπ) ℓ$$ \overline{\nu} $$

Angular analysis of Λb→ Λc(→ Λπ) ℓ$$ \overline{\nu} $$

Angular analysis of the rare decay $$ {\Lambda}_b\to \Lambda (1520)\left(\to N\overline{K}\right){\ell}^{+}{\ell}^{-} $$

Lepton flavor violating $$\Lambda _b\rightarrow \Lambda \ell _1\ell _2$$ decay

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