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 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.

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.

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.

New Constraints on the Axion–Photon Coupling Constant for Solar Axions

JETP Letters ◽  
2018 ◽  
Vol 107 (10) ◽  
pp. 589-594 ◽  
Author(s):  
Yu. M. Gavrilyuk ◽  
A. N. Gangapshev ◽  
A. V. Derbin ◽  
I. S. Drachnev ◽  
V. V. Kazalov ◽  
...  
Keyword(s):  
Coupling Constant ◽  
Solar Axions ◽  
Photon Coupling

The Regulation and Control of Electromagnetically Induced Transparency and Absorption in an Optical-radio Two-photon Coupling Configuration

2017 ◽  
Vol 46 (6) ◽  
pp. 626001
Author(s):  
张玮峰 ZHANG Wei-feng ◽  
苑青 YUAN Qing ◽  
李晓莉 LI Xiao-li ◽  
尚雅轩 SHANG Ya-xuan ◽  
张连水 ZHANG Lian-shui
Keyword(s):  
Electromagnetically Induced Transparency ◽  
Two Photon ◽  
And Control ◽  
Induced Transparency ◽  
Photon Coupling

scholarly journals Thermodynamics of Charged Rotating Dilaton Black Branes Coupled to Logarithmic Nonlinear Electrodynamics

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
A. Sheykhi ◽  
M. H. Dehghani ◽  
M. Kord Zangeneh
Keyword(s):  
Thermal Stability ◽  
Electromagnetic Coupling ◽  
Nonlinear Electrodynamics ◽  
Black Brane ◽  
Dilaton Field ◽  
Coupling Constant ◽  
De Sitter ◽  
New Class ◽  
Unstable Phase ◽  
Complete Set

We construct a new class of charged rotating black brane solutions in the presence of logarithmic nonlinear electrodynamics with complete set of the rotation parameters in arbitrary dimensions. The topology of the horizon of these rotating black branes is flat, while due to the presence of the dilaton field the asymptotic behavior of them is neither flat nor (anti-)de Sitter [(A)dS]. We investigate the physical properties of the solutions. The mass and angular momentum of the spacetime are obtained by using the counterterm method inspired by AdS/CFT correspondence. We derive temperature, electric potential, and entropy associated with the horizon and check the validity of the first law of thermodynamics on the black brane horizon. We study thermal stability of the solutions in both canonical and grand-canonical ensemble and disclose the effects of the rotation parameter, nonlinearity of electrodynamics, and dilaton field on the thermal stability conditions. We find the solutions are thermally stable forα<1, while forα>1the solutions may encounter an unstable phase, whereαis dilaton-electromagnetic coupling constant.

SCALE DEPENDENCE OF TWIST-3 CORRELATION FUNCTIONS

2011 ◽  
Vol 04 ◽  
pp. 146-156
Author(s):  
Zhong-Bo Kang ◽  
Jian-Wei Qiu
Keyword(s):  
Correlation Functions ◽  
Evolution Equations ◽  
Scale Dependence ◽  
Leading Order ◽  
Coupling Constant ◽  
Parton Distributions ◽  
Spin Asymmetries ◽  
Single Spin ◽  
Single Spin Asymmetries ◽  
Similarities And Differences

In this talk, we introduce two sets of twist-3 quark-gluon correlation functions that are relevant to transverse single spin asymmetries, and present corresponding evolution equations at the leading order in strong coupling constant, αs. The similarities and differences between the evolution of the leading power parton distributions and that of the twist-3 multiparton correlation functions are also discussed.

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