scholarly journals The D∗Dπ and B∗Bπ couplings from light-cone sum rules

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Alexander Khodjamirian ◽  
Blaženka Melić ◽  
Yu-Ming Wang ◽  
Yan-Bing Wei
Keyword(s):  
Correlation Function ◽  
Lattice Qcd ◽  
Light Cone ◽  
Sum Rules ◽  
Analytical Form ◽  
Operator Product ◽  
Decay Constants ◽  
Meson Coupling ◽  
Double Dispersion ◽  
First Time

Abstract We revisit the calculation of the strong couplings D∗Dπ and B∗Bπ from the QCD light-cone sum rules using the pion light-cone distribution amplitudes. The accuracy of the correlation function, calculated from the operator product expansion near the light-cone, is upgraded by taking into account the gluon radiative corrections to the twist-3 terms. The double spectral density of the correlation function, including the twist-2, 3 terms at $$ \mathcal{O}\left({\alpha}_s\right) $$ O α s and the twist-4 LO terms, is presented in an analytical form for the first time. This form allows us to use various versions of the quark-hadron duality regions in the double dispersion relation underlying the sum rules. We predict $$ {g}_{D^{\ast } D\pi}={14.1}_{-1.2}^{+1.3} $$ g D ∗ Dπ = 14.1 − 1.2 + 1.3 and $$ {g}_{B^{\ast } B\pi}={30.0}_{-2.4}^{+2.6} $$ g B ∗ Bπ = 30.0 − 2.4 + 2.6 when the decay constants of heavy mesons entering the light-cone sum rule are taken from lattice QCD results. We compare our results with the experimental value for the charmed meson coupling and with the lattice QCD calculations.

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.

scholarly journals SCALING RELATION FOR THE $\Upsilon (4S)\to B\bar{B}$ AND $\psi (3770)\to D\bar{D}$ DECAY CONSTANTS FROM PHENOMENOLOGICAL SUM RULES

1995 ◽  
Vol 10 (28) ◽  
pp. 2113-2123 ◽  
Author(s):  
V.V. KISELEV
Keyword(s):  
Sum Rules ◽  
Heavy Meson ◽  
Scaling Relation ◽  
Coupling Constant ◽  
Exclusive Production ◽  
Decay Constants ◽  
Meson Coupling ◽  
Decay Widths ◽  
Heavy Quark Limit ◽  
Pair Contribution

The sum rules for exclusive production of heavy meson pairs in e+e− annihilation are used to evaluate the [Formula: see text] and [Formula: see text] decay widths. Infinitely heavy quark limit is discussed, and the scaling relation for the quarkonium-meson coupling constant is derived. The [Formula: see text] pair contribution into the leptonic constant fϒ(4S) is estimated.

scholarly journals Strong decay constants of heavy tensor mesons in light cone QCD sum rules

2016 ◽  
Vol 2016 (4) ◽  
pp. 1-16 ◽  
Author(s):  
H. A. Alhendi ◽  
T. M. Aliev ◽  
M. Savcı
Keyword(s):  
Light Cone ◽  
Sum Rules ◽  
Strong Decay ◽  
Qcd Sum Rules ◽  
Decay Constants

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 The ground states and the first radially excited states of D-wave vector ρ and ϕ mesons

2021 ◽  
Author(s):  
Guo-Liang Yu ◽  
Zhi-Gang Wang ◽  
Xiu-Wu Wang ◽  
Hui-Juan Wang
Keyword(s):  
Excited States ◽  
Wave Vector ◽  
Operator Product Expansion ◽  
Sum Rules ◽  
Ground States ◽  
Operator Product ◽  
Decay Constants ◽  
Vector Formula ◽  
Vacuum Condensates ◽  
D Wave

In this paper, we first derive two QCD sum rules QCDSR I and QCDSR II which are, respectively, used to extract observable quantities of the ground states and the first radially excited states of the D-wave vector [Formula: see text] and [Formula: see text] mesons. In our calculations, we consider the contributions of vacuum condensates up to dimension-7 in the operator product expansion. The predicted masses for [Formula: see text] [Formula: see text] meson and [Formula: see text] [Formula: see text] meson are consistent well with the experimental data of [Formula: see text]([Formula: see text]) and [Formula: see text]([Formula: see text]), respectively. Besides, our analysis indicates that it is reliable to assign the recent reported [Formula: see text]([Formula: see text]) state as the [Formula: see text] [Formula: see text] meson. Finally, we obtain the decay constants of these states with QCDSR I and QCDSR II. These predictions are helpful not only to reveal the structure of the newly observed [Formula: see text]([Formula: see text]) state, but also to establish [Formula: see text] meson and [Formula: see text] meson families.

scholarly journals Analysis of the triply heavy baryon states with the QCD sum rules

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Zhi-Gang Wang
Keyword(s):  
Mass Spectrum ◽  
Ground State ◽  
Operator Product Expansion ◽  
Sum Rules ◽  
Heavy Baryon ◽  
Operator Product ◽  
Qcd Sum Rules ◽  
Gluon Condensates ◽  
First Time ◽  
Vacuum Condensates

AbstractIn this article, we reexamine the mass spectrum of the ground state triply heavy baryon states with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension 6 in a consistent way and preforming a novel analysis. It is for the first time to take into account the three-gluon condensates in the QCD sum rules for the triply heavy baryon states.

scholarly journals QUASILOCAL QUARK MODELS AS EFFECTIVE THEORY OF NON-PERTURBATIVE QCD

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1850-1854 ◽  
Author(s):  
A. A. ANDRIANOV ◽  
V. A. ANDRIANOV
Keyword(s):  
Perturbative Qcd ◽  
Chiral Symmetry ◽  
Sum Rules ◽  
Axial Vector ◽  
Effective Theory ◽  
Operator Product ◽  
Decay Constants ◽  
Intermediate Energies ◽  
Quark Models ◽  
Meson States

We consider the Quasilocal Quark Model of NJL type (QNJLM) as an effective theory of non-perturbative QCD including scalar (S), pseudoscalar (P), vector (V) and axial-vector (A) four-fermion interaction with derivatives. In the presence of a strong attraction in the scalar channel the chiral symmetry is spontaneously broken and as a consequence the composite meson states are generated in all channels. With the help of Operator Product Expansion the appropriate set of Chiral Symmetry Restoration (CSR) Sum Rules in these channels are imposed as matching conditions to QCD at intermediate energies. The mass spectrum and some decay constants for ground and excited meson states are calculated.

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 The semi-leptonic form factors of $$\Lambda _{b}\rightarrow \Lambda _{c}$$ and $$\Xi _{b}\rightarrow \Xi _{c}$$ in QCD sum rules

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Zhen-Xing Zhao ◽  
Run-Hui Li ◽  
Yue-Long Shen ◽  
Yu-Ji Shi ◽  
Yan-Sheng Yang
Keyword(s):  
Correlation Function ◽  
Lattice Qcd ◽  
Sum Rules ◽  
Form Factors ◽  
Leading Order ◽  
Qcd Sum Rules ◽  
Point Correlation ◽  
Point Correlation Function

AbstractIn this work, the full leading order results of the form factors for $$\Xi _{b}\rightarrow \Xi _{c}$$ Ξ b → Ξ c and $$\Lambda _{b}\rightarrow \Lambda _{c}$$ Λ b → Λ c are obtained in QCD sum rules. Contributions from up to dimension-5 have been considered. For completeness, we also study the two-point correlation function to obtain the pole residues of $$\Xi _{Q}$$ Ξ Q and $$\Lambda _{Q}$$ Λ Q , and higher accuracy is achieved. For the three-point correlation function, since stable Borel regions cannot be found, about $$20\%$$ 20 % uncertainties are introduced for the form factors of $$\Xi _{b}\rightarrow \Xi _{c}$$ Ξ b → Ξ c and $$\Lambda _{b}\rightarrow \Lambda _{c}$$ Λ b → Λ c . Our results for the form factors are consistent with those of the lattice QCD within errors.

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