CHARM 2018 CHARM 2018 Review of recent developments on leptonic and semileptonic charm decays from lattice QCD Università di Roma Tre, INFN Roma Tre, LPT Orsay Università di Roma Tre, INFN Roma Tre, LPT Orsay
Lattjce QCD Non-perturbative QCD contributions from fjrst principles Control all systematic uncertainties ✦ Discrete Euclidean Space-Time ✦ Finite spatial volume and time extent ✦ Path integrals rigorously defjned and computed via Monte Carlo methods CHARM 2018 1/23 Giorgio Salerno
Lattjce QCD Non-perturbative QCD contributions from fjrst principles Control all systematic uncertainties Parameters in a simulation: ✦ Lattice spacing: ✦ Finite volume and time: ✦ Quark masses: ✦ # see quarks: CHARM 2018 2/23 Giorgio Salerno
Lattjce QCD QCD recovered by removing cutofgs ✦ Continuum limit: ✦ Infjnite volume limit: ✦ Interpolation/Extrapolation to physical quark masses: T o reliably estimate systematic errors: repeat the calculation for several lattice spacing, volumes and sea-quark masses CHARM 2018 3/23 Giorgio Salerno
Lattjce QCD - State of the art [G. Herdoiza summer 2015 + (partial) updates, C. Pena] CHARM 2018 4/23 Giorgio Salerno
Quark masses on the lattjce Light quarks: discretization errors fjnite size efgects Extrapolation in m u,d often necessary (ChPT) Heavy quarks: discretization errors ● Charm quarks: directly accessible on the lattice ● Bottom quarks: extrapolation or an efgective theory (HQET, NRQCD, ...) is needed CHARM 2018 5/23 Giorgio Salerno
Euclidean Correlators Masses and hadronic matrix elements are extracted from Euclidean Correlators 7/21 6/23 CHARM 2018 Giorgio Salerno
Leptonic decays Decay constants (Lattice QCD) Decay rate CKM matrix elements (Experiments) ● Experimental + LQCD inputs for the determination of CKM elements ● Systematic and statistical errors cancellation in the SU(3) ratio LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 7/23
Leptonic decays - FLAG FNAL/MILC 14A ETM 14E ● Improved action ● Improved action ● Physical mass: ● Physical mass: ● ● LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 8/23
Leptonic decays – New Results RBC/UKQCD ● DW fermions ● Physical mass: ● ● Giorgio Salerno LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 9/23
Leptonic decays – New Results RBC/UKQCD Giorgio Salerno LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 10/23
Leptonic decays – New Results FNAL/MILC ● ● 20 ensembles ● Light-quark mass down to ● down to ● Very high statistics (1000x4 samples) ● Big volumes (up to: 144 3 x 288, 6 fm ) LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 11/23
Leptonic decays – New Results FNAL/MILC LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 12/23
Semileptonic decays CKM matrix elements Form factors (Lattice QCD) ● Experimental + LQCD inputs for the determination of CKM elements ● Determination of the forms factors in all the physical q2 range ● Momentum dependence of the tensor form factor for BSM analysis LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 13/23
Semileptonic decays - FLAG HPQCD ● fmavors of HISQ ● Improved action ● Physical mass: ● ● No renormalization ● D at rest frame ● Modifjed z-expansion ● f 0 from the Scalar matrix element LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 14/23
Semileptonic decays - New Results New (Preliminary) (B. Chakraborty) @ LATTICE 2017 HPQCD ● ● Physical u/d quarks ● fmavors of HISQ ● Both f + and f 0 over whole q 2 -range ● Improved action ● Physical mass: ● ● No renormalization ● D at rest frame ● Modifjed z-expansion ● f 0 from the Scalar matrix element LATTICE 2017 Giorgio Salerno CHARM 2018 Giorgio Salerno 15/23
Semileptonic decays - New Results ETMC ● fmavors of tmW ● Improved action ● Physical mass: ● ● No renormalization ● f +,0 and f T over whole q 2 -range ● Hypercubic discretization efgects ● Modifjed z-expansion ● Vector & Scalar matrix elements LATTICE 2017 Giorgio Salerno CHARM 2018 Giorgio Salerno 16/23
Semileptonic decays - New Results f 0 (q 2 ) and f + (q 2 ) at the physical point ETMC Giorgio Salerno CHARM 2018 17/23
Semileptonic decays - New Results JLQCD (T. Kaneko) @ LATTICE 2017 Preliminary ● of DW fermions ● New ensembles: fjne lattice spacing ● Improved action ● Physical mass: ● ● Both f + and f 0 over whole q 2 -range ● D at rest frame ● q 2 =0 through BCL z-expansion LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 18/23
Semileptonic decays - New Results JLQCD (T. Kaneko) @ LATTICE 2017 Preliminary LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 19/23
Summary of results y r a n i m i l e r P LATTICE 2017 1/22 Giorgio Salerno CHARM 2018 Giorgio Salerno 20/23
Determinatjon of V cd and V cs V cd(s) from semileptonic decays (errors dominated by theoretical inputs) V cd(s) from leptonic decays (errors dominated by experimental inputs) Giorgio Salerno CHARM 2018 21/23
CKM 2nd-row Unitarity Giorgio Salerno CHARM 2018 22/23
Conclusions & Outlooks ✦ LQCD simulations with very small lattice spacings and light see quarks at their physical masses are being performed ● No need (reduced) of chiral extrapolation better precision ✦ LQCD predictions of the decay constants of the D and D s mesons are very precise (errors below 1%, now ~0.2%). Uncertainties in CKM matrix elements dominated by experimental inputs ● New determinations are required to confjrm systematic errors are under control ✦ Determinations of D (s) semileptonic form factors still need to be improved. Uncertainties in CKM matrix elements dominated by LQCD inputs ● f +,0 over whole q 2 -range ● f T over whole q 2 -range CHARM 2018 Giorgio Salerno 23/23
Thank you for the attention CHARM 2018 Giorgio Salerno
Other results ETMC CLS ensembles B. Blossier, J. Heitger, M. Post CHARM 2018 Giorgio Salerno
Extractjon of the form factors The two semileptonic form factors f 0 and f + can be determined from the matrix element of the vector current An alternative way to determine f 0 is to use the scalar density Giorgio Salerno CHARM 2018
Simulatjon Details To inject momenta we used non-periodic boundary conditions Both the D and the π(K) mesons can have non-zero momentum CHARM 2018 Giorgio Salerno
Lorentz Symmetry Breaking f 0 vs. q 2 (GeV 2 ) corrected uncorrected CHARM 2018 Giorgio Salerno
Results In the continuum limit Giorgio Salerno CHARM 2018
Determinatjon of V cd and V cs Giorgio Salerno CHARM 2018
3-points correlators From 2-point Form factors correlators Giorgio Salerno CHARM 2018
Euclidean Correlators Calculated on the lattice (Importance sampling Monte Carlo) Statistical error CHARM 2018 Giorgio Salerno
Quenching Gaussian integral for anticommutative (Grassmann) variables det M encodes the contribution of see quark loops CHARM 2018 Giorgio Salerno
Modifjed z-expansion and have a polynomial dependence on and are parameters left free to move in the fit CHARM 2018 Giorgio Salerno
ETMC – Tensor form factor f T (q 2 ) at the physical point ETMC Giorgio Salerno CHARM 2018
Recommend
More recommend
