Search for manifestations of new physics in fermion-pair production at LEP

Abstract:We present an analysis of the rare exclusive B decays B → Kνν and B → K * νν within the Standard Model (SM), in a model-independent manner, and in a number of new physics (NP) models. Combining new form factor determinations from lattice QCD with light-cone sum rule results and including complete two-loop electroweak corrections to the SM Wilson coefficient, we obtain the SM predictions BR(B + → K + νν) = (4.0 ± 0.5) × 10 −6 and BR(B 0 → K * 0 νν) = (9.2 ± 1.0) × 10 −6 , more precise and more robust than previous estimates. Beyond the SM, we make use of an effective theory with dimension-six operators invariant under the SM gauge symmetries to relate NP effects in b → sνν transitions to b → s + − transitions and use the wealth of experimental data on B → K ( * ) + − and related modes to constrain NP effects in B → K ( * ) νν. We then consider several specific NP models, including Z models, the MSSM, models with partial compositeness, and leptoquark models, demonstrating that the correlations between b → sνν observables among themselves and with B s → µ + µ − and b → s + − transitions offer powerful tests of NP with new right-handed couplings and non-MFV interactions.

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“…Here we have again assumed LFU. In that case, the lepton couplings are constrained from LEP2 searches for contact interactions [55,56],…”

Section: General Z Modelsmentioning

confidence: 99%

B → K ∗ ν ν ¯ $$ B\to {K}^{\left(\ast \right)}\nu \overline{\nu} $$ decays in the Standard Model and beyond

Buras

Girrbach-Noe

Niehoff

et al. 2015

J. High Energ. Phys.

260

166

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“…LEP bound on resonant e + e − → τ + τ − production [90] can be used to put bounds on the X coupling to leptons.…”

Section: Lepmentioning

confidence: 99%

Flavor gauge models below the Fermi scale

Babu

Friedland

Machado

et al. 2017

J. High Energ. Phys.

120

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The mass and weak interaction eigenstates for the quarks of the third generation are very well aligned, an empirical fact for which the Standard Model offers no explanation. We explore the possibility that this alignment is due to an additional gauge symmetry in the third generation. Specifically, we construct and analyze an explicit, renormalizable model with a gauge boson, X, corresponding to the B − L symmetry of the third family. Having a relatively light (in the MeV to multi-GeV range), flavor-nonuniversal gauge boson results in a variety of constraints from different sources. By systematically analyzing 20 different constraints, we identify the most sensitive probes: kaon, B + , D + and Upsilon decays, D −D 0 mixing, atomic parity violation, and neutrino scattering and oscillations. For the new gauge coupling g X in the range (10 −2 -10 −4 ) the model is shown to be consistent with the data. Possible ways of testing the model in b physics, top and Z decays, direct collider production and neutrino oscillation experiments, where one can observe nonstandard matter effects, are outlined. The choice of leptons to carry the new force is ambiguous, resulting in additional phenomenological implications, such as nonuniversality in semileptonic bottom decays. The proposed framework provides interesting connections between neutrino oscillations, flavor and collider physics.

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“…However, contact interaction bounds are not quoted on operators of the form (e i P L e j )(e j P R e i ), corresponding to iijj 'e . Such operators are generated by sneutrino exchange in R-parity violating SUSY, so we estimate the bound 2 =m 2 < 4=(9 TeV 2 ) from the plotted constraints in [186], and impose 4j (1)ee . The bounds in these two columns apply also when the flavour indices are permuted to jilk and ilkj.…”

Section: Four-charged-lepton Operatorsmentioning

confidence: 99%

Flavor physics of leptons and dipole moments

Raidal¹,

Schaaf²,

Bigi³

et al. 2009

Flavor in the Era of the LHC

Self Cite

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This chapter of the report of the "Flavour in the era of the LHC" Workshop discusses the theoretical, phenomenological and experimental issues related to flavour phenomena in the charged lepton sector and in flavour-conserving CP-violating processes. We review the current experimental limits and the main theoretical models for the flavour structure of fundamental particles. We analyze the phenomenological consequences of the available data, setting constraints on explicit models beyond the Standard Model, presenting benchmarks for the discovery potential of forthcoming measurements both at the LHC and at low energy, and exploring options for possible future experiments.

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Search for manifestations of new physics in fermion-pair production at LEP

Cited by 57 publications

References 41 publications

B → K ∗ ν ν ¯ $$ B\to {K}^{\left(\ast \right)}\nu \overline{\nu} $$ decays in the Standard Model and beyond

B → K ∗ ν ν ¯ $$ B\to {K}^{\left(\ast \right)}\nu \overline{\nu} $$ decays in the Standard Model and beyond

Flavor gauge models below the Fermi scale

Flavor physics of leptons and dipole moments

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