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Ulfg Meisner - One of the best experts on this subject based on the ideXlab platform.
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b s k l overline nu angular analysis s wave contributions and v ub
Journal of High Energy Physics, 2014Co-Authors: Ulfg Meisner, Wei WangAbstract:We analyse the $ \overline{B}_s^0\to {K^{+}}{l^{-}}\overline{\nu} $ and $ \overline{B}_s^0\to {K^{*+ }}\left( {\to K\pi } \right){\ell^{-}}\overline{\nu} $ decays that are valuable for extracting the CKM matrix element |V ub|. We calculate the differential and integrated partial widths in units of |V ub|2 based on various calculations of hadronic Form factors and in particular the latest Lattice QCD calculation of the B s → K * Form factors. For the decay $ \overline{B}_s^0\to K\pi \ell \overline{\nu} $ , we Formulate the general angular distributions with the inclusion of the various partial-wave Kπ contributions. Using the results for the Kπ Scalar Form factor calculated from unitarized chiral perturbation theory, we explore the S-wave effects on angular distribution variables and demonstrate that they may not be negligible, considering the high precision expected in future measurements. We also briefly discuss the impact of the S-wave ππ contributions in the $ {B^{-}}\to {\pi^{+}}{\pi^{-}}\ell \overline{v} $ decay and provide estimates for the mode $ {B^{-}}\to {K^{+}}{K^{-}}\ell \overline{\nu} $ . The studies of these channels in future can not only be used to determine |V ub|, but may also provide valuable inFormation on the Kπ and ππ phase shifts.
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chiral dynamics and s wave contributions in semileptonic b decays
Journal of High Energy Physics, 2013Co-Authors: M Doring, Ulfg Meisner, Wei WangAbstract:The flavor-changing neutral current process b → sl + l − is beneficial to testing the standard model and hunting for new physics scenarios. In exclusive decay modes like B → K * (892)l + l −, the S-wave effects may not be negligible and thus have to be reliably estimated. Using the Scalar Form factors derived from dispersion relations in two channels and matched to Chiral Perturbation Theory, we investigate the S-wave contributions in $ {{\overline{B}}^0}\to {K^{-}}{\pi^{+}}{l^{+}}{l^{-}} $ , with the Kπ invariant mass lying in the vicinity of the mass of K * (892), and B s → K − K + l + l − with m KK ~ m ϕ . We find that the S-wave will modify differential decay widths by about 10% in the process of $ {{\overline{B}}^0}\to {K^{-}}{\pi^{+}}{l^{+}}{l^{-}} $ and about 5% in B s → K − K + l + l −. A forward-backward asymmetry for the charged kaon in the final state arises from the interference between the S-wave and P-wave contributions. The measurement of this asymmetry offers a new way to determine the variation of the Kπ S-wave phase versus the invariant mass.
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chiral dynamics and s wave contributions in semileptonic b decays
arXiv: High Energy Physics - Phenomenology, 2013Co-Authors: M Doring, Ulfg Meisner, Wei WangAbstract:The flavor-changing neutral current process $b\to s l^+l^-$ is beneficial to testing the standard model and hunting for new physics scenarios. In exclusive decay modes like $B\to K^*(892)l^+l^-$, the S-wave effects may not be negligible and thus have to be reliably estimated. Using the Scalar Form factors derived from dispersion relations in two channels and matched to Chiral Perturbation Theory, we investigate the S-wave contributions in $\bar B^0\to K^- \pi^+ l^+l^-$, with the $K\pi$ invariant mass lying in the vicinity of the mass of $K^*(892)$, and the $B_s\to K^- K^+ l^+l^-$ with $m_{KK}\sim m_{\phi}$. We find that the S-wave will modify differential decay widths by about 10% in the process of $\bar B^0\to K^- \pi^+ l^+l^-$ and about 5% in $B_s\to K^- K^+ l^+l^-$. A forward-backward asymmetry for the charged kaon in the final state arises from the interference between the S-wave and P-wave contributions. The measurement of this asymmetry offers a new way to determine the variation of the $K\pi$ S-wave phase versus the invariant mass.
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dispersive analysis of the Scalar Form factor of the nucleon
Journal of High Energy Physics, 2012Co-Authors: Martin Hoferichter, Christoph Ditsche, Bastian Kubis, Ulfg MeisnerAbstract:Based on the recently proposed Roy-Steiner equations for pion-nucleon (πN) scattering [1], we derive a system of coupled integral equations for the $ \pi \pi \to \overline N N $ and $ \overline K K \to \overline N N $ S-waves. These equations take the Form of a two-channel Muskhelishvili-Omnes problem, whose solution in the presence of a finite matching point is discussed. We use these results to update the dispersive analysis of the Scalar Form factor of the nucleon fully including $ \overline K K $ intermediate states. In particular, we determine the correction $ {\Delta_{\sigma }} = \sigma \left( {2M_{\pi }^2} \right) - {\sigma_{{\pi N}}} $ , which is needed for the extraction of the pion-nucleon σ term from πN scattering, as a function of pion-nucleon subthreshold parameters and the πN coupling constant.
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dispersive analysis of the Scalar Form factor of the nucleon
arXiv: High Energy Physics - Phenomenology, 2012Co-Authors: Martin Hoferichter, Christoph Ditsche, Bastian Kubis, Ulfg MeisnerAbstract:Based on the recently proposed Roy-Steiner equations for pion-nucleon scattering, we derive a system of coupled integral equations for the pi pi --> N-bar N and K-bar K --> N-bar N S-waves. These equations take the Form of a two-channel Muskhelishvili-Omnes problem, whose solution in the presence of a finite matching point is discussed. We use these results to update the dispersive analysis of the Scalar Form factor of the nucleon fully including K-bar K intermediate states. In particular, we determine the correction Delta_sigma=sigma(2M_pi^2)-sigma_{pi N}, which is needed for the extraction of the pion-nucleon sigma term from pi N scattering, as a function of pion-nucleon subthreshold parameters and the pi N coupling constant.
Wei Wang - One of the best experts on this subject based on the ideXlab platform.
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chiral dynamics and s wave contributions in semileptonic d s b s decays into π π
Physical Review D, 2015Co-Authors: Yuji Shi, Wei WangAbstract:In this work, we study the semileptonic decay modes ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ and ${D}_{s}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}\ensuremath{\nu}$ in the kinematics region where the ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ system has a invariant mass in the range 0.5--1.3 GeV. These processes are valuable towards the determination of S-wave ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ light-cone distribution amplitudes whose normalizations are Scalar Form factors. We compare the results for Scalar Form factors predicted in unitarized chiral perturbation theory and extracted from the data on the ${B}_{s}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. Then the ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${D}_{s}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ Form factors are calculated in light-cone sum rules, based on which predictions for differential decay widths are made. The results are in good agreement with the experimental data on the ${B}_{s}$ and ${D}_{s}$ decays into ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$. More accurate measurements at BEPC, LHC and KEKB in the future will be helpful to examine our Formalism and constrain the input parameters more precisely.
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s wave resonance contributions to the b s 0 j ψ π π and b s π π μ μ decays
Physical Review D, 2015Co-Authors: W H Wang, Wei WangAbstract:We study $S$-wave resonance contributions to the ${B}_{(s)}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ and ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decays in the perturbative QCD framework by introducing two-hadron distribution amplitudes for final states. The Breit--Wigner Formula for the ${f}_{0}(500)$, ${f}_{0}(1500)$, and ${f}_{0}(1790)$ resonances and the Flatt\'e model for the ${f}_{0}(980)$ resonance are adopted to parametrize the timelike Scalar Form factors in the two-pion distribution amplitudes, which include both resonant and nonresonant contributions. The resultant branching fraction and differential branching fraction in the pion-pair invariant mass for each resonance channel are consistent with experimental data. The determined $S$-wave two-pion distribution amplitudes, containing the inFormation of both resonant and nonresonant rescattering phases, can be employed to predict direct $CP$ asymmetries of other three-body hadronic $B$ meson decays in various localized regions of two-pion phase space.
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s wave resonance contributions to the b s 0 j ψ π π and b s π π μ μ decays
Physical Review D, 2015Co-Authors: Wei WangAbstract:We study S-wave resonance contributions to the B-(s)(0) -> J/psi pi(+)pi(-) and B-s -> pi(+)pi(-)mu(+)mu(-) decays in the perturbative QCD framework by introducing two-hadron distribution amplitudes for final states. The Breit-Wigner Formula for the f(0)(500), f(0)(1500), and f(0)(1790) resonances and the Flatte model for the f(0)(980) resonance are adopted to parametrize the timelike Scalar Form factors in the two-pion distribution amplitudes, which include both resonant and nonresonant contributions. The resultant branching fraction and differential branching fraction in the pion-pair invariant mass for each resonance channel are consistent with experimental data. The determined S-wave two-pion distribution amplitudes, containing the inFormation of both resonant and nonresonant rescattering phases, can be employed to predict direct CP asymmetries of other three-body hadronic B meson decays in various localized regions of two-pion phase space.
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b s k l overline nu angular analysis s wave contributions and v ub
Journal of High Energy Physics, 2014Co-Authors: Ulfg Meisner, Wei WangAbstract:We analyse the $ \overline{B}_s^0\to {K^{+}}{l^{-}}\overline{\nu} $ and $ \overline{B}_s^0\to {K^{*+ }}\left( {\to K\pi } \right){\ell^{-}}\overline{\nu} $ decays that are valuable for extracting the CKM matrix element |V ub|. We calculate the differential and integrated partial widths in units of |V ub|2 based on various calculations of hadronic Form factors and in particular the latest Lattice QCD calculation of the B s → K * Form factors. For the decay $ \overline{B}_s^0\to K\pi \ell \overline{\nu} $ , we Formulate the general angular distributions with the inclusion of the various partial-wave Kπ contributions. Using the results for the Kπ Scalar Form factor calculated from unitarized chiral perturbation theory, we explore the S-wave effects on angular distribution variables and demonstrate that they may not be negligible, considering the high precision expected in future measurements. We also briefly discuss the impact of the S-wave ππ contributions in the $ {B^{-}}\to {\pi^{+}}{\pi^{-}}\ell \overline{v} $ decay and provide estimates for the mode $ {B^{-}}\to {K^{+}}{K^{-}}\ell \overline{\nu} $ . The studies of these channels in future can not only be used to determine |V ub|, but may also provide valuable inFormation on the Kπ and ππ phase shifts.
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chiral dynamics and s wave contributions in semileptonic b decays
Journal of High Energy Physics, 2013Co-Authors: M Doring, Ulfg Meisner, Wei WangAbstract:The flavor-changing neutral current process b → sl + l − is beneficial to testing the standard model and hunting for new physics scenarios. In exclusive decay modes like B → K * (892)l + l −, the S-wave effects may not be negligible and thus have to be reliably estimated. Using the Scalar Form factors derived from dispersion relations in two channels and matched to Chiral Perturbation Theory, we investigate the S-wave contributions in $ {{\overline{B}}^0}\to {K^{-}}{\pi^{+}}{l^{+}}{l^{-}} $ , with the Kπ invariant mass lying in the vicinity of the mass of K * (892), and B s → K − K + l + l − with m KK ~ m ϕ . We find that the S-wave will modify differential decay widths by about 10% in the process of $ {{\overline{B}}^0}\to {K^{-}}{\pi^{+}}{l^{+}}{l^{-}} $ and about 5% in B s → K − K + l + l −. A forward-backward asymmetry for the charged kaon in the final state arises from the interference between the S-wave and P-wave contributions. The measurement of this asymmetry offers a new way to determine the variation of the Kπ S-wave phase versus the invariant mass.
Veronique Bernard - One of the best experts on this subject based on the ideXlab platform.
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Chiral extrapolation of the strangeness changing Scalar Kπ Form factor
Journal of High Energy Physics, 2010Co-Authors: Veronique Bernard, Emilie PassemarAbstract:We perForm a chiral extrapolation of lattice data on the Scalar Kπ Form factor and the ratio of the kaon and pion decay constants within Chiral Perturbation Theory to two loops. We determine the value of the Scalar Form factor at zero momentum transfer, at the Callan-Treiman point and at its soft kaon analog as well as its slope. Results are in good agreement with their determination from experiment using the standard couplings of quarks to the W boson. The slope is however rather large. A study of the convergence of the chiral expansion is also perFormed.
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matching chiral perturbation theory and the dispersive representation of the Scalar kπ Form factor
Physics Letters B, 2008Co-Authors: Veronique Bernard, Emilie PassemarAbstract:Abstract We perForm a matching of the two loop-chiral perturbation theory representation of the Scalar Kπ Form factor to a dispersive one. Knowing the value of F K / F π and f + ( 0 ) in the Standard Model (SM) allows to determine two O ( p 6 ) LECs, the slope of the Scalar Form factor and the deviation of the Callan–Treiman theorem. Going beyond the SM and assuming the knowledge of the slope of the Scalar Form factor from experiment, the matching allows us to determine the ratio of F K / F π , f + ( 0 ) , a certain combination of non-standard couplings, the deviation of the Callan–Treiman theorem and the two O ( p 6 ) LECs.
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on the analysis of the pion nucleon σ term the size of the remainder at the cheng dashen point
Physics Letters B, 1996Co-Authors: Veronique Bernard, N Kaiser, Ulfg MeisnerAbstract:Abstract We calculate the one-loop contributions of order M π 4 to the difference Δ R between the on-shell pion-nucleon scattering amplitude D + (0, 2M π 2 ) at the Cheng-Dashen point ν = 0, t = 2 M π 2 and the Scalar Form factor σ (2 M π 2 ) in the framework of heavy baryon chiral perturbation theory. We proof that to this order Δ R contains no chiral logarithms and therefore it vanishes simply as M π 4 in the chiral limit. Numerically, we find as an upper limit Δ R ⋍ 2 MeV .
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on the analysis of the pion nucleon sigma term the size of the remainder at the cheng dashen point
arXiv: High Energy Physics - Phenomenology, 1996Co-Authors: Veronique Bernard, N Kaiser, Ulfg MeisnerAbstract:We calculate the one--loop contributions of order $M_\pi^4$ to the difference $\Delta_R$ between the on--shell pion--nucleon scattering amplitude $\bar{D}^+(0,2M_\pi^2)$ at the Cheng--Dashen point $\nu =0$, $t=2M_\pi^2$ and the Scalar Form factor $\sigma (2M_\pi^2)$ in the framework of heavy baryon chiral perturbation theory. We proof that to this order $\Delta_R$ contains $no$ chiral logarithms and therefore it vanishes simply as $M_\pi^4$ in the chiral limit. Numerically, we find as an upper limit $\Delta_R \simeq 2\,$MeV.
Emilie Passemar - One of the best experts on this subject based on the ideXlab platform.
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Chiral extrapolation of the strangeness changing Scalar Kπ Form factor
Journal of High Energy Physics, 2010Co-Authors: Veronique Bernard, Emilie PassemarAbstract:We perForm a chiral extrapolation of lattice data on the Scalar Kπ Form factor and the ratio of the kaon and pion decay constants within Chiral Perturbation Theory to two loops. We determine the value of the Scalar Form factor at zero momentum transfer, at the Callan-Treiman point and at its soft kaon analog as well as its slope. Results are in good agreement with their determination from experiment using the standard couplings of quarks to the W boson. The slope is however rather large. A study of the convergence of the chiral expansion is also perFormed.
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matching chiral perturbation theory and the dispersive representation of the Scalar kπ Form factor
Physics Letters B, 2008Co-Authors: Veronique Bernard, Emilie PassemarAbstract:Abstract We perForm a matching of the two loop-chiral perturbation theory representation of the Scalar Kπ Form factor to a dispersive one. Knowing the value of F K / F π and f + ( 0 ) in the Standard Model (SM) allows to determine two O ( p 6 ) LECs, the slope of the Scalar Form factor and the deviation of the Callan–Treiman theorem. Going beyond the SM and assuming the knowledge of the slope of the Scalar Form factor from experiment, the matching allows us to determine the ratio of F K / F π , f + ( 0 ) , a certain combination of non-standard couplings, the deviation of the Callan–Treiman theorem and the two O ( p 6 ) LECs.
J Shigemitsu - One of the best experts on this subject based on the ideXlab platform.
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d k lν semileptonic decay Scalar Form factor and v cs from lattice qcd
Physical Review D, 2010Co-Authors: C T H Davies, Eduardo Follana, Peter G Lepage, J ShigemitsuAbstract:We present a new study of D semileptonic decays on the lattice which employs the highly improved staggered quark action for both the charm and the light valence quarks. We work with MILC unquenched N f = 2 + 1 lattices and determine the Scalar Form factor f 0 (q 2 ) for D → K, lv semileptonic decays. The Form factor is obtained from a Scalar current matrix element that does not require any operator matching. We develop a new approach to carrying out chiral/continuum extrapolations of f 0 (q 2 ). The method uses the kinematic "z"variable instead of q 2 or the kaon energy E K and is applicable over the entire physical q 2 range. We find f D→K 0 (0) ≡ f D→K + (0) = 0.747(19) in the chiral plus continuum limit and hereby improve the theory error on this quantity by a factor of ~4 compared to previous lattice determinations. Combining the new theory result with recent experimental measurements of the product f D→K + (0) * |V cs | from BABAR and CLEO-c leads to a very precise direct determination of the CKM matrix element |V cs |, |V cs | = 0.961 ( 11 )(24), where the first error comes from experiment and the second is the lattice QCD theory error. We calculate the ratio f D→K + (0)f Ds and find 2.986 ± 0.087 GeV -1 and show that this agrees with experiment.
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d k l ν semileptonic decay Scalar Form factor and v c s from lattice qcd
Physical Review D, 2010Co-Authors: C T H Davies, Eduardo Follana, Peter G Lepage, J ShigemitsuAbstract:We present a new study of $D$ semileptonic decays on the lattice which employs the highly improved staggered quark action for both the charm and the light valence quarks. We work with MILC unquenched ${N}_{f}=2+1$ lattices and determine the Scalar Form factor ${f}_{0}({q}^{2})$ for $D\ensuremath{\rightarrow}K$, $l\ensuremath{\nu}$ semileptonic decays. The Form factor is obtained from a Scalar current matrix element that does not require any operator matching. We develop a new approach to carrying out chiral/continuum extrapolations of ${f}_{0}({q}^{2})$. The method uses the kinematic ``$z$''variable instead of ${q}^{2}$ or the kaon energy ${E}_{K}$ and is applicable over the entire physical ${q}^{2}$ range. We find ${f}_{0}^{D\ensuremath{\rightarrow}K}(0)\ensuremath{\equiv}{f}_{+}^{D\ensuremath{\rightarrow}K}(0)=0.747(19)$ in the chiral plus continuum limit and hereby improve the theory error on this quantity by a factor of $\ensuremath{\sim}4$ compared to previous lattice determinations. Combining the new theory result with recent experimental measurements of the product ${f}_{+}^{D\ensuremath{\rightarrow}K}(0)*|{V}_{cs}|$ from BABAR and CLEO-c leads to a very precise direct determination of the CKM matrix element $|{V}_{cs}|$, $|{V}_{cs}|=0.961(11)(24)$, where the first error comes from experiment and the second is the lattice QCD theory error. We calculate the ratio ${f}_{+}^{D\ensuremath{\rightarrow}K}(0)/{f}_{{D}_{s}}$ and find $2.986\ifmmode\pm\else\textpm\fi{}0.087\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ and show that this agrees with experiment.
