Flavour physics from lattice QCD

Gámiz, Elvira

doi:10.48550/arxiv.1303.3971

“…which are not yet included in the FLAG average but having smaller errors are consistent with the latter Evidently there is a big progress in determining all these relevant parameters but one would like to decrease the errors further and it appears that this should be possible in the coming years. Selected reviews about the status and prospects can be found in [62,[121][122][123][124][125].…”

Section: Step 2: Improved Lattice Calculations Of Hadronic Parametersmentioning

confidence: 99%

“…In order to simplify the presentation we still work with η Y and Y 0 (x t ) which should be replaced by Y eff in (123) if the future precision of experimental data will require it.…”

Section: Tree-level Gauge Boson Exchangementioning

confidence: 99%

Towards the Identification of New Physics through Quark Flavour Violating Processes

Buras,

Girrbach

2013

Preprint

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We outline a systematic strategy which should help in this decade to identify New Physics (NP) beyond the Standard Model (SM) by means of quark flavour violating processes and thereby to extend the picture of short distance physics down to the scales as short as 10 −20 m and even shorter distance scales corresponding to energies of 100 TeV. Rather than using all possible flavour violating observables that will be measured in the coming years at the LHC, SuperKEKB and in Kaon physics dedicated experiments at CERN, J-PARC and Fermilab, we concentrate on those observables that are theoretically clean and very sensitive to NP. Assuming that the data on the selected observables by us will be very precise, we stress the importance of correlations between these observables as well as of future precise calculations of non-perturbative parameters by means of lattice QCD simulations with dynamical fermions. Our strategy consists of twelve steps which we will discuss in detail illustrating possible outcomes with the help of the SM, models with constrained Minimal Flavour Violation (CMFV), MFV at large and models with tree-level FCNCs mediated by neutral gauge bosons and scalars. We also briefly summarize the status of a number of concrete models. We propose DNA-charts that exhibit correlations between flavour observables in different NP scenarios. The models with new left-handed and/or right-handed currents and non-MFV interactions can be distinguished transparently in this manner. We emphasize the important role of the stringent CMFV relations between various observables as standard candles of flavour physics. The pattern of deviations from these relations may help in identifying the correct NP scenario. The success of this program will be very much facilitated through direct signals of NP at the LHC even if LHC will not be able to probe the physics at scales shorter than 4×10 −20 m. We also emphasize the importance of lepton flavour violation, electric dipole moments and (g − 2) e,µ in these studies.

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“…For the numerics in Section 3 we however use the relation (11) without the lattice input, except for Eq. ( 29) below where we use (13).…”

Section: ∆F = 2 Observablesmentioning

confidence: 99%

“…Before entering our analysis we want to find the range for γ by using the range for ξ in Table 1 together with formulae (11) and (14). We find independently of S(v) (15) GeV [37] m Bs = 5366.8(2) MeV [38] sin 2 θ W = 0.23116 (13) [37] F B d = (188 ± 4) MeV [36] α(M Z ) = 1/127.9 [37] F Bs = (225 ± 3) MeV [36] α s (M Z ) = 0.1184 (7) [37] (11), BBs = 1.33 (6)[20] m d (2 GeV) = (4.73 ± 0.12) MeV [20] BBs / BB d = 1.05 (7) [20] (11) MeV [20] S ψK S = 0.679 (20) [37] BK = 0.767 (10) [20] S ψφ = −0.01 ± 0.08 [45] κ ǫ = 0.94 (2) [6, 34] ∆Γ s = 0.116 ± 0.019 [46] η cc = 1.87 (76) [47] τ Bs = 1.503 (10) ps [44] η tt = 0.5765 (65) [41] τ B d = 1.519( 7) ps [44] η ct = 0.496 (47) [48] τ B ± = (1641 ± 8) × 10…”

Section: Numerical Analysismentioning

confidence: 99%

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Stringent tests of constrained Minimal Flavor Violation through ΔF=2 transitions

Buras¹,

Girrbach²

2013

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New Physics contributions to ∆F = 2 transitions in the simplest extensions of the Standard Model (SM), the models with constrained Minimal Flavour Violation (CMFV), are parametrized by a single variable S(v), the value of the real box diagram function that in CMFV is bounded from below by its SM value S 0 (x t ). With already very precise experimental values of ε K , ∆M d , ∆M s and precise values of the CP-asymmetry S ψK S and ofB K entering the evaluation of ε K , the future of CMFV in the ∆F = 2 sector depends crucially on the values of |V cb |, |V ub |, γ, F Bs B Bs and F B d B B d . The ratio ξ of the latter two non-perturbative parameters, already rather precisely determined from lattice calculations, allows then together with ∆M s /∆M d and S ψK S to determine the range of the angle γ in the unitarity triangle independently of the value of S(v). Imposing in addition the constraints from |ε K | and ∆M d allows to determine the favorite CMFV values of |V cb |, |V ub |, F Bs B Bs and F B d B B d as functions of S(v) andγ. The |V cb | 4 dependence of ε K allows to determine |V cb | for a given S(v) and γ with a higher precision than it is presently possible using tree-level decays. The same applies to |V ub |, |V td | and |V ts | that are automatically determined as functions of S(v) and γ. We derive correlations between F Bs B Bs and F B d B B d , |V cb |, |V ub | and γ that should be tested in the coming years. Typically F Bs B Bs and F B d B B d have to be significantly lower than their present lattice values, while |V cb | has to be significantly higher than its tree-level determination. The region in the space of these three parameters allowed by CMFV indicates visible problems in this class of models and hints for the presence of new sources of flavour violation and/or new local operators in ∆F = 2 data that are strongly suppressed in these models. As a byproduct we propose to reduce the present uncertainty in the charm contribution to ε K by using the experimental value of ∆M K .

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Towards the identification of new physics through quark flavour violating processes

Buras

¹

,

Girrbach

²

2014

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We outline a systematic strategy which should help in this decade to identify New Physics (NP) beyond the Standard Model (SM) by means of quark flavour violating processes and thereby to extend the picture of short distance physics down to the scales as short as 10 −20 m and even shorter distance scales corresponding to energies of 100 TeV. Rather than using all possible flavour violating observables that will be measured in the coming years at the LHC, SuperKEKB and in Kaon physics dedicated experiments at CERN, J-PARC and Fermilab, we concentrate on those observables that are theoretically clean and very sensitive to NP. Assuming that the data on the selected observables by us will be very precise, we stress the importance of correlations between these observables as well as of future precise calculations of non-perturbative parameters by means of lattice QCD simulations with dynamical fermions. Our strategy consists of twelve steps which we will discuss in detail illustrating possible outcomes with the help of the SM, models with constrained Minimal Flavour Violation (CMFV), MFV at large and models with tree-level FCNCs mediated by neutral gauge bosons and scalars. We also briefly summarize the status of a number of concrete models. We propose DNA-charts that exhibit correlations between flavour observables in different NP scenarios. The models with new left-handed and/or right-handed currents and non-MFV interactions can be distinguished transparently in this manner. We emphasize the important role of the stringent CMFV relations between various observables as standard candles of flavour physics. The pattern of deviations from these relations may help in identifying the correct NP scenario. The success of this program will be very much facilitated through direct signals of NP at the LHC even if LHC will not be able to probe the physics at scales shorter than 4×10 −20 m. We also emphasize the importance of lepton flavour violation, electric dipole moments and (g − 2) e,µ in these studies.

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Flavour physics from lattice QCD

Cited by 3 publications

References 44 publications

Towards the Identification of New Physics through Quark Flavour Violating Processes

Towards the Identification of New Physics through Quark Flavour Violating Processes

Stringent tests of constrained Minimal Flavor Violation through ΔF=2 transitions

Towards the identification of new physics through quark flavour violating processes

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