scholarly journals The $$ \overline{B} $$ → π form factors from QCD and their impact on |Vub|

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Domagoj Leljak ◽  
Blaženka Melić ◽  
Danny van Dyk
Keyword(s):  
Form Factor ◽  
Lattice Qcd ◽  
Sum Rules ◽  
Semileptonic Decay ◽  
Form Factors ◽  
Scalar Form Factor ◽  
Small Momentum Transfer ◽  
Scalar Form ◽  
Sum Rule ◽  
First Time

Abstract We revisit light-cone sum rules with pion distribution amplitudes to determine the full set of local $$ \overline{B} $$ B ¯ → π form factors. To this end, we determine all duality threshold parameters from a Bayesian fit for the first time. Our results, obtained at small momentum transfer q2, are extrapolated to large q2 where they agree with precise lattice QCD results. We find that a modification to the commonly used BCL parametrization is crucial to interpolate the scalar form factor between the two q2 regions. We provide numerical results for the form factor parameters — including their covariance — based on simultaneous fit of all three form factors to both the sum rule and lattice QCD results. Our predictions for the form factors agree well with measurements of the q2 spectrum of the semileptonic decay $$ {\overline{B}}^0\to {\pi}^{+}{\mathrm{\ell}}^{-}{\overline{\nu}}_{\mathrm{\ell}} $$ B ¯ 0 → π + ℓ − ν ¯ ℓ . From the world average of the latter we obtain |Vub| = (3.77 ± 0.15) · 10−3, which is in agreement with the most recent inclusive determination at the 1 σ level.

scholarly journals Scalar form factor of the proton with light-cone QCD sum rules

2006 ◽  
Vol 73 (9) ◽  
Author(s):  
Zhi-Gang Wang ◽  
Shao-Long Wan ◽  
Wei-Min Yang
Keyword(s):  
Form Factor ◽  
Light Cone ◽  
Sum Rules ◽  
Scalar Form Factor ◽  
Qcd Sum Rules ◽  
Scalar Form

scholarly journals Scalar Form Factor of the Pion in the Kroll-Lee-Zumino Field Theory

2015 ◽  
Vol 2015 ◽  
pp. 1-4
Author(s):  
C. A. Dominguez ◽  
M. Loewe ◽  
M. Lushozi
Keyword(s):  
Field Theory ◽  
Form Factor ◽  
Lattice Qcd ◽  
Leading Order ◽  
Scalar Form Factor ◽  
Perturbative Calculations ◽  
Scalar Form ◽  
Rho Meson ◽  
The Masses

The renormalizable Kroll-Lee-Zumino field theory of pions and a neutral rho-meson is used to determine the scalar form factor of the pion in the space-like region at next-to-leading order. Perturbative calculations in this framework are parameter-free, as the masses and the rho-pion-pion coupling are known from experiment. Results compare favorably with lattice QCD calculations.

scholarly journals Semileptonic decay of $$\varOmega _c^0 \rightarrow \varXi ^- l^+ \nu _l$$ from light-cone sum rules

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Hui-Hui Duan ◽  
Yong-Lu Liu ◽  
Ming-Qiu Huang
Keyword(s):  
Decay Width ◽  
Light Cone ◽  
Sum Rules ◽  
Semileptonic Decay ◽  
Decay Channel ◽  
Branching Ratio ◽  
Form Factors ◽  
Weak Decay ◽  
Decay Process ◽  
Sum Rule

AbstractThe weak decay process of $$\varOmega _c$$ Ω c to $$\varXi $$ Ξ is calculated in the method of QCD light-cone sum rule. The decay width of $$\varOmega _c^0 \rightarrow \varXi ^- l^+ \nu _l$$ Ω c 0 → Ξ - l + ν l and its decay branching ratio are also calculated with the form factors from this work’s calculation. To the twist-6 distribution amplitudes, the form factors $$f_1=0.66\pm 0.02, f_2=-0.76\pm 0.03, g_1=0.06\pm 0.01$$ f 1 = 0.66 ± 0.02 , f 2 = - 0.76 ± 0.03 , g 1 = 0.06 ± 0.01 and $$g_2=-0.44\pm 0.01$$ g 2 = - 0.44 ± 0.01 are given at zero recoil point. The result of the semileptonic decay width of $$\varOmega _c^0 \rightarrow \varXi ^-l^+\nu _l$$ Ω c 0 → Ξ - l + ν l is $$\varGamma =(7.51\pm 0.36)\times 10^{-15}~\mathrm{{GeV}}$$ Γ = ( 7.51 ± 0.36 ) × 10 - 15 GeV , and the prediction of the decay branching ratio $$Br(\varOmega _c^0\rightarrow \varXi ^-l^+\nu _l)=(3.06\pm 0.15)\times 10^{-3}$$ B r ( Ω c 0 → Ξ - l + ν l ) = ( 3.06 ± 0.15 ) × 10 - 3 . These results fit well with other works, and the decay width and branching ratio are improved. This not too small branching ratio gives a good direction to explore this decay channel in the future experiments.

scholarly journals Radiative decays of heavy-light mesons and the $$ {f}_{H,{H}^{\ast },{H}_1}^{(T)} $$ decay constants

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Ben Pullin ◽  
Roman Zwicky
Keyword(s):  
Sum Rules ◽  
Form Factors ◽  
Radiative Decays ◽  
Matrix Elements ◽  
Leading Order ◽  
Sum Rule ◽  
Decay Constants ◽  
Leptonic Decays ◽  
Shell Matrix ◽  
First Time

Abstract The on-shell matrix elements, or couplings $$ {g}_{H{H}^{\ast}\left({H}_1\right)\upgamma} $$ g H H ∗ H 1 γ , describing the $$ B{(D)}_q^{\ast } $$ B D q ∗ → B(D)qγ and B1q → Bqγ (q = u, d, s) radiative decays, are determined from light-cone sum rules at next-to-leading order for the first time. Two different interpolating operators are used for the vector meson, providing additional robustness to our results. For the D*-meson, where some rates are experimentally known, agreement is found. The couplings are of additional interest as they govern the lowest pole residue in the B(D) → γ form factors which in turn are connected to QED-corrections in leptonic decays B(D) → ℓ$$ \overline{\nu} $$ ν ¯ . Since the couplings and residues are related by the decay constants $$ {f}_{H^{\ast}\left({H}_1\right)} $$ f H ∗ H 1 and $$ {f}_{H^{\ast}\left({H}_1\right)}^T $$ f H ∗ H 1 T , we determine them at next-leading order as a by-product. The quantities $$ \left\{{f}_{H^{\ast}}^T,{f}_{H_1}^T\right\} $$ f H ∗ T f H 1 T have not previously been subjected to a QCD sum rule determination. All results are compared with the existing experimental and theoretical literature.

scholarly journals D→K,lνsemileptonic decay scalar form factor and|Vcs|from lattice QCD

2010 ◽  
Vol 82 (11) ◽  
Author(s):  
Heechang Na ◽  
Christine T. H. Davies ◽  
Eduardo Follana ◽  
G. Peter Lepage ◽  
Junko Shigemitsu
Keyword(s):  
Form Factor ◽  
Lattice Qcd ◽  
Scalar Form Factor ◽  
Scalar Form

scholarly journals THE ROLE OF $K^*_0(1430)$ IN D → PK AND τ → KPντ DECAYS

1999 ◽  
Vol 14 (26) ◽  
pp. 4161-4175 ◽  
Author(s):  
S. FAJFER ◽  
J. ZUPAN
Keyword(s):  
Experimental Data ◽  
Form Factor ◽  
Matrix Element ◽  
Scalar Meson ◽  
Final State Interaction ◽  
Form Factors ◽  
Decay Rates ◽  
Scalar Form Factor ◽  
Meson Resonance ◽  
Scalar Form

We consider the scalar form factor in the weak current matrix element <PK|jμ|0>, P=π, η, η′. It obtains the contributions from the scalar meson resonance [Formula: see text] and from the scalar projection of the vector meson K*(892) resonance. We analyze decay amplitudes of the Cabibbo suppressed decays D → KP, P=π, η, η′ using the factorization approach. The form factors of the relevant matrix elements are described by assuming the dominance of nearby resonances. The annihilation contribution in these decays arises from the matrix element <PK|jμ|0>. All the required parameters are experimentally known except the scalar meson [Formula: see text] decay constant. We fit the decay amplitudes and we find that final state interaction improves the agreement with the experimental data. Then we extract bounds on scalar form factor parameters and compare them with the experimental data obtained in the analyses of K→πeνe and K→πμνμ. The same scalar form factor is present in the τ → KPντ decay, with P=π, η, η′. Using the obtained bounds we investigate the significance of the scalar meson form factor in the τ→ KPντ, P=π, η, η′ decay rates and spectra. We find that the [Formula: see text] scalar meson dominates in the τ→Kη′ντ decay spectrum.

scholarly journals Light-cone sum rules for proton decay

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ulrich Haisch ◽  
Amando Hala
Keyword(s):  
Lattice Qcd ◽  
Light Cone ◽  
Sum Rules ◽  
State Of The Art ◽  
Form Factors ◽  
Baryon Number ◽  
Proton Decay ◽  
Matrix Elements ◽  
Decay Channels ◽  
Systematic Uncertainties

Abstract We estimate the form factors that parametrise the hadronic matrix elements of proton-to-pion transitions with the help of light-cone sum rules. These form factors are relevant for semi-leptonic proton decay channels induced by baryon-number violating dimension-six operators, as typically studied in the context of grand unified theories. We calculate the form factors in a kinematical regime where the momentum transfer from the proton to the pion is space-like and extrapolate our final results to the regime that is relevant for proton decay. In this way, we obtain estimates for the form factors that show agreement with the state-of-the-art calculations in lattice QCD, if systematic uncertainties are taken into account. Our work is a first step towards calculating more involved proton decay channels where lattice QCD results are not available at present.

Sign in / Sign up

Export Citation Format

Share Document