Author: Emel Gulez
Publisher:
ISBN:
Category : B mesons
Languages : en
Pages : 116
Book Description
Abstract: We present state-of-the-art unquenched lattice QCD results for B meson semileptonic decay, B [rightarrow] [pi]lv, form factors. We use gauge configurations prepared by the MILC collaboration, which include the effects of the sea quarks, the s quark and two very light quarks (u and d). We employ the nonrelativistic NRQCD action to simulate the heavy b quark and a highly improved staggered quark action (AsqTad) to simulate the sea and valence light quarks. To reduce the uncertainties, we perform matching of the heavy-light current with these highly improved actions through one loop. The perturbative matching accounts for the effects of mixing with dimension 4 operators that are O(1/M) and O(a). We extrapolate the form factors f+(q2) and f0(q2) to their values at the physical pion mass using chiral perturbation theory formulas. Integrating this result, we obtain [integral] [from] 16 GeV2 [to] q2_max [d[gamma]/dq2]d2 (V_ub)2 = 1.46(35) ps−1. Combining this with a preliminary average by the Heavy Flavor Averaging Group (HFAG'05) of recent branching fraction data for exclusive B semileptonic decays from the BaBar, Belle and CLEO collaborations, leads to V_ub = 4.22(30)(51) x 10−3.
B Meson Semileptonic Form Factors Using Unquenched Lattice QCD
Author: Emel Gulez
Publisher:
ISBN:
Category : B mesons
Languages : en
Pages : 116
Book Description
Abstract: We present state-of-the-art unquenched lattice QCD results for B meson semileptonic decay, B [rightarrow] [pi]lv, form factors. We use gauge configurations prepared by the MILC collaboration, which include the effects of the sea quarks, the s quark and two very light quarks (u and d). We employ the nonrelativistic NRQCD action to simulate the heavy b quark and a highly improved staggered quark action (AsqTad) to simulate the sea and valence light quarks. To reduce the uncertainties, we perform matching of the heavy-light current with these highly improved actions through one loop. The perturbative matching accounts for the effects of mixing with dimension 4 operators that are O(1/M) and O(a). We extrapolate the form factors f+(q2) and f0(q2) to their values at the physical pion mass using chiral perturbation theory formulas. Integrating this result, we obtain [integral] [from] 16 GeV2 [to] q2_max [d[gamma]/dq2]d2 (V_ub)2 = 1.46(35) ps−1. Combining this with a preliminary average by the Heavy Flavor Averaging Group (HFAG'05) of recent branching fraction data for exclusive B semileptonic decays from the BaBar, Belle and CLEO collaborations, leads to V_ub = 4.22(30)(51) x 10−3.
Publisher:
ISBN:
Category : B mesons
Languages : en
Pages : 116
Book Description
Abstract: We present state-of-the-art unquenched lattice QCD results for B meson semileptonic decay, B [rightarrow] [pi]lv, form factors. We use gauge configurations prepared by the MILC collaboration, which include the effects of the sea quarks, the s quark and two very light quarks (u and d). We employ the nonrelativistic NRQCD action to simulate the heavy b quark and a highly improved staggered quark action (AsqTad) to simulate the sea and valence light quarks. To reduce the uncertainties, we perform matching of the heavy-light current with these highly improved actions through one loop. The perturbative matching accounts for the effects of mixing with dimension 4 operators that are O(1/M) and O(a). We extrapolate the form factors f+(q2) and f0(q2) to their values at the physical pion mass using chiral perturbation theory formulas. Integrating this result, we obtain [integral] [from] 16 GeV2 [to] q2_max [d[gamma]/dq2]d2 (V_ub)2 = 1.46(35) ps−1. Combining this with a preliminary average by the Heavy Flavor Averaging Group (HFAG'05) of recent branching fraction data for exclusive B semileptonic decays from the BaBar, Belle and CLEO collaborations, leads to V_ub = 4.22(30)(51) x 10−3.
Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD.
Bπ Excited State Contamination in B Meson Observables Obtained from Lattice QCD
Author: Alexander Broll
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Englische Version: Lattice simulations of Quantum Chromodynamics allow for a fully non-perturbative computation of hadronic correlation functions, but for a reliable extraction of physical quantities such as particle energies and matrix elements the contribution of excited states needs to be under control. In this thesis, an effective field theory known as Heavy Meson Chiral Perturbation Theory (HM ChPT) is used to analytically compute the dominant excited states contamination of B meson correlators which are relevant for the extraction of CKM matrix elements. First, the analogues of the quark bilinears which are used as interpolating fields in lattice simulations are derived in HM ChPT. These depend on a set of low energy constants (LECs) which are known for local fields. On the other hand, smeared interpolating fields can be incorporated in the effective theory by changing the values of these LECs, a fact that will be used throughout this thesis for investigating the effect of smearing. The interpolating fields are used to compute the B meson two-point function from which the B meson mass and decay constant as well as the respective excited states contamination can be extracted. From suitably chosen ratios of three-point functions and two-point functions, the HM ChPT LEC g, the form factors of semileptonic B meson decay, and the matrix elements of neutral B meson oscillations were determined. The computed excited states contamination of these ratios usually leads to an overestimation of the order of a few percent, depending on the values chosen for the LECs. Some results depend on so far unknown LECs, for which suitable correlation functions for a lattice determination are presented. In contrast, the excited states contamination of one of the semileptonic form factors is an order of magnitude larger and negative.
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Englische Version: Lattice simulations of Quantum Chromodynamics allow for a fully non-perturbative computation of hadronic correlation functions, but for a reliable extraction of physical quantities such as particle energies and matrix elements the contribution of excited states needs to be under control. In this thesis, an effective field theory known as Heavy Meson Chiral Perturbation Theory (HM ChPT) is used to analytically compute the dominant excited states contamination of B meson correlators which are relevant for the extraction of CKM matrix elements. First, the analogues of the quark bilinears which are used as interpolating fields in lattice simulations are derived in HM ChPT. These depend on a set of low energy constants (LECs) which are known for local fields. On the other hand, smeared interpolating fields can be incorporated in the effective theory by changing the values of these LECs, a fact that will be used throughout this thesis for investigating the effect of smearing. The interpolating fields are used to compute the B meson two-point function from which the B meson mass and decay constant as well as the respective excited states contamination can be extracted. From suitably chosen ratios of three-point functions and two-point functions, the HM ChPT LEC g, the form factors of semileptonic B meson decay, and the matrix elements of neutral B meson oscillations were determined. The computed excited states contamination of these ratios usually leads to an overestimation of the order of a few percent, depending on the values chosen for the LECs. Some results depend on so far unknown LECs, for which suitable correlation functions for a lattice determination are presented. In contrast, the excited states contamination of one of the semileptonic form factors is an order of magnitude larger and negative.
Unquenched B Meson Decay Constants and Neutral B Meson-antineutral B Meson Mixing Parameters from Chiral Lattice QCD
Measurement of B Meson Semileptonic Decay Form Factors
Form Factors for Semileptonic Bs -> Klv Decays in Lattice QCD
Form Factors for Semileptonic Bs → Klν Decays in Lattice QCD
B Meson Decay Constant from Quenched Lattice QCD
Measurements of the Branching Fractions and Form Factor of Semileptonic Decays of B Mesons to D Mesons
Lepton Photon Interactions At High Energies (Lepton Photon 2017) - Proceedings Of The 28th International Symposium
Author: Wang Wei
Publisher: World Scientific
ISBN: 9811207410
Category : Science
Languages : en
Pages : 576
Book Description
The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.
Publisher: World Scientific
ISBN: 9811207410
Category : Science
Languages : en
Pages : 576
Book Description
The latest of the 'Lepton Photon' symposium, one of the well-established series of meetings in the high-energy physics community, was successfully organized at the South Campus of Sun Yat-sen University, Guangzhou, China, from August 7-12, 2017, where physicists around the world gathered to discuss the latest advancements in the research field.This proceedings volume of the Lepton Photon 2017 collects contributions by the plenary session speakers and the posters' presenters, which cover the latest results in particle physics, nuclear physics, astrophysics, cosmology, and plans for future facilities.