scholarly journals DECAY CONSTANTS OF PSEUDOSCALAR MESONS IN BETHE–SALPETER FRAMEWORK WITH GENERALIZED STRUCTURE OF HADRON-QUARK VERTEX

2009 ◽  
Vol 18 (07) ◽  
pp. 1521-1533 ◽  
Author(s):  
SHASHANK BHATNAGAR ◽  
SHI-YUAN LI
Keyword(s):  
Power Counting ◽  
Meson Mass ◽  
Dirac Structure ◽  
Leading Order ◽  
Counting Rule ◽  
Decay Constants ◽  
Leptonic Decays ◽  
Pseudoscalar Mesons ◽  
Complete Set ◽  
Rule Order

We employ the framework of Bethe–Salpeter equation under Covariant Instantaneous Ansatz to study the leptonic decays of pseudoscalar mesons. The Dirac structure of hadron-quark vertex function Γ is generalized to include various Dirac covariants besides γ5 from their complete set. The covariants are incorporated in accordance with a power counting rule, order-by-order in powers of the inverse of the meson mass. The decay constants are calculated with the incorporation of leading order covariants. Most of the results are dramatically improved.

TWO PHOTON DECAYS OF PION IN BETHE–SALPETER FRAMEWORK WITH GENERALIZED STRUCTURE OF HADRON-QUARK VERTEX

2008 ◽  
Vol 17 (03) ◽  
pp. 519-530
Author(s):  
SHASHANK BHATNAGAR
Keyword(s):  
Power Counting ◽  
Meson Mass ◽  
Leading Order ◽  
Coupling Constant ◽  
Counting Rule ◽  
Leptonic Decays ◽  
Two Photon ◽  
Pseudoscalar Mesons ◽  
Complete Set ◽  
Photon Coupling

Two photon decays of pion are studied in the framework of the Bethe–Salpeter equation under Covariant Instantaneous Ansatz where the structure of hadron-quark vertex function Γ is generalized to include various Dirac covariants (other than γ5) from their complete set. These covariants are incorporated in accordance with a power counting rule (which was recently employed to calculate leptonic decays constants of pseudoscalar mesons and vector mesons) order by order in powers of the inverse of the meson mass. Pion-photon coupling constant Fπ is calculated with the incorporation of leading order covariants.

scholarly journals POWER COUNTING OF VARIOUS DIRAC COVARIANTS IN HADRONIC BETHE–SALPETER WAVE FUNCTIONS FOR PSEUDOSCALAR MESON DECAYS

2011 ◽  
Vol 20 (06) ◽  
pp. 1437-1454 ◽  
Author(s):  
SHASHANK BHATNAGAR ◽  
SHI-YUAN LI ◽  
JORGE MAHECHA
Keyword(s):  
Wave Function ◽  
Radiative Decay ◽  
Power Counting ◽  
Wave Functions ◽  
Dirac Structure ◽  
Leading Order ◽  
Counting Rule ◽  
Decay Constants ◽  
Pseudoscalar Mesons ◽  
Complete Set

We have employed the framework of Bethe–Salpeter equation under covariant instantaneous ansatz to calculate leptonic decay constants of unequal mass pseudoscalar mesons like π±, K, D, DS and B, and radiative decay constants of neutral pseudoscalar mesons like π0 and ηc into two photons. In the Dirac structure of hadronic Bethe–Salpeter wave function, the covariants are incorporated from their complete set in accordance with a recently proposed power counting rule. The contribution of both leading order and next-to-leading order Dirac covariants to decay constants are studied. The results are found to improve and hence validating the power counting rule which provides a practical means of incorporating Dirac covariants in the Bethe–Salpeter wave function for a hadron.

WEAK LEPTONIC DECAY OF LIGHT AND HEAVY PSEUDOSCALAR MESONS IN A FIELD-THEORETIC QUARK MODEL

1993 ◽  
Vol 08 (29) ◽  
pp. 2775-2783 ◽  
Author(s):  
L. MAHARANA ◽  
A. NATH ◽  
A. R. PANDA
Keyword(s):  
Harmonic Oscillator ◽  
Quark Model ◽  
Constituent Quark ◽  
Leptonic Decay ◽  
Decay Constants ◽  
Quark Masses ◽  
Leptonic Decays ◽  
Pseudoscalar Mesons ◽  
Oscillator Wave Function ◽  
Harmonic Oscillator Wave Function

Weak leptonic decays of light and heavy pseudoscalar mesons are studied in a field-theoretic quark model where the mesons are described by constituent quarks and antiquarks with a particular ansatz and a Harmonic oscillator wave function. With constituent quark masses and Harmonic oscillator radii for mesons as parameters of the model, decay constants are calculated and found as (fπ, fk, fD, fB) = (132 MeV , 161 MeV , 160 MeV , 115 MeV ) indicating a reasonable agreement with the experimental data wherever available. Partial decay widths and branching ratios for kinematically allowed leptonic decay processes are also estimated and compared with the experiments wherever available.

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 AssociatedZ0H0production with leptonic decays at the LHC in next-to-leading order QCD

2012 ◽  
Vol 86 (3) ◽  
Author(s):  
Zhang Shi-Ming ◽  
Zhang Ren-You ◽  
Ma Wen-Gan ◽  
Guo Lei
Keyword(s):  
Leading Order ◽  
Leptonic Decays

scholarly journals Study of Rare Mesonic Decays Involving Di-Neutrinos in Their Final State

2018 ◽  
Vol 2018 ◽  
pp. 1-20
Author(s):  
Azeem Mir ◽  
Farida Tahir ◽  
Shakeel Mahmood ◽  
Shi- Hai Dong
Keyword(s):  
Branching Fractions ◽  
New Physics ◽  
Supersymmetric Model ◽  
Final State ◽  
Yukawa Couplings ◽  
Leptonic Decays ◽  
Pseudoscalar Mesons ◽  
Theoretical Predictions ◽  
Minimal Supersymmetric Model

We have studied phenomenological implication of R-parity violating (Rp) Minimal Supersymmetric Model (MSSM) via analyses of pure leptonic (M→νν¯) and semileptonic decays of pseudoscalar mesons (M→Xνν¯). These analyses involve comparison between theoretical predictions made by Rp MSSM and the Standard Model (SM) with the experimental results like branching fractions (Br) of the said process. We have found, in general, that Rp contribution dominates over the SM contribution, i.e., by a factor of 10 for the pure leptonic decays of KL,S and by 102 and 104 in case of Bs and Bd, respectively. Furthermore, the limits obtained on Rp Yukawa couplings (λαkβ′λαkγ′⁎) by using Br  (M→Xνν¯) are used to calculate Br  (M→νν¯). This demonstrates the role of Rp MSSM as a viable model for the study of new physics contribution in rare decays at places like Super B factories, KOTO (J-PARC) and NA62 at CERN.

scholarly journals The one-loop tadpole in the geoSMEFT

2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Tyler Corbett
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Effective Field ◽  
Power Counting ◽  
Leading Order ◽  
The Standard Model ◽  
The One ◽  
Near Future ◽  
Geometric Formulation

Making use of the geometric formulation of the Standard Model Effective Field Theory we calculate the one-loop tadpole diagrams to all orders in the Standard Model Effective Field Theory power counting. This work represents the first calculation of a one-loop amplitude beyond leading order in the Standard Model Effective Field Theory, and discusses the potential to extend this methodology to perform similar calculations of observables in the near future.

scholarly journals Leptonic Decays of Heavy Quarks on the Lattice

1997 ◽  
Vol 12 (25) ◽  
pp. 4477-4538 ◽  
Author(s):  
Hartmut Wittig
Keyword(s):  
Cp Violation ◽  
Continuum Limit ◽  
Systematic Errors ◽  
Decay Constants ◽  
Leptonic Decays ◽  
The Standard Model ◽  
Lattice Calculations ◽  
The Status ◽  
Lattice Approach ◽  
The Continuum

The status of lattice calculations of heavy-light decay constants and of the B parameter BB is reviewed. After describing the lattice approach to heavy quark systems, the main results are discussed, with special emphasis on the systematic errors in present lattice calculations. A detailed analysis of the continuum limit for decay constants is performed. The implications of lattice results on studies of CP violation in the Standard Model are discussed.

Mass spectrum and leptonic decay constants of ground and radially excited states of ηc and ηb in a Bethe–Salpeter equation framework

2015 ◽  
Vol 24 (04) ◽  
pp. 1550030 ◽  
Author(s):  
Hluf Negash ◽  
Shashank Bhatnagar
Keyword(s):  
Mass Spectrum ◽  
Excited States ◽  
Ground State ◽  
Reasonable Agreement ◽  
Equal Mass ◽  
Leptonic Decay ◽  
Decay Constants ◽  
Pseudoscalar Mesons

In this paper, we study the mass spectrum and decay constants of ground state (1S) and radially excited states (2S and 3S) of heavy equal mass pseudoscalar mesons, ηc and ηb. We have employed the framework of Bethe–Salpeter equation (BSE) under Covariant Instantaneous Ansatz (CIA). Our predictions are in reasonable agreement with the data on available states and results of other models.

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