scholarly journals FORM FACTORS FOR B→πlν DECAY IN A MODEL CONSTRAINED BY CHIRAL SYMMETRY AND QUARK MODEL

2002 ◽  
Vol 17 (32) ◽  
pp. 4927-4938 ◽  
Author(s):  
RIAZUDDIN ◽  
T. A. AL-AITHAN ◽  
AMJAD HUSSAIN SHAH GILANI
Keyword(s):  
Vector Meson ◽  
Quark Model ◽  
Chiral Symmetry ◽  
B Meson ◽  
Valence Quark ◽  
Form Factors ◽  
Pole Mass ◽  
Equal Time ◽  
Quark Contribution ◽  
Momentum Transfer Range

The form factors for the B→π transition are evaluated in the entire momentum transfer range by using the constraints obtained in the framework combining the heavy quark expansion and chiral symmetry for light quarks and the quark model. In particular, we calculate the valence quark contribution and show that it together with the equal time commutator contribution give to the form factors a pole behavior with the heavy (B-meson in our case) mass as the pole mass. This is in addition to the usual vector meson B*-pole diagram for B→πlν in the above framework. We discuss the predictions in our model, which provide an estimate of |Vub|2.

QUARK-PION COUPLING CONSTANT IN AN INDEPENDENT-QUARK MODEL WITH CHIRAL SYMMETRY

1993 ◽  
Vol 08 (07) ◽  
pp. 607-617 ◽  
Author(s):  
S.N. JENA ◽  
S. PANDA
Keyword(s):  
Vector Meson ◽  
Quark Model ◽  
Chiral Symmetry ◽  
Finite Size ◽  
Meson Decay ◽  
Width Ratio ◽  
Coupling Constant ◽  
Confining Potential ◽  
Pion Nucleon ◽  
Good Agreement

Incorporating chiral symmetry into an independent-quark model with the confining potential Vq(r) = ½(1 + γ0)(a2r + V0), the quark-pion coupling constant for quarks in a nucleon are estimated. The values of [Formula: see text] obtained with the approximation of a point pion as well as finite size pion are consistent with that extracted from the experimental vector meson decay width ratio Γ(ρ → π+π0)/Γ(ρ → π- ν) by Suzuki and Bhaduri. The pion-nucleon coupling constant [Formula: see text] comes out to be 14.98 in good agreement with the experimental value.

scholarly journals RESUMMATION STUDY ON VECTOR MESON DECAYS AND CHIRAL SYMMETRY SPONTANEOUSLY BREAKING IN CHIRAL CONSTITUENT QUARK MODEL

2004 ◽  
Vol 19 (01) ◽  
pp. 81-114
Author(s):  
YI-BIN HUANG ◽  
MU-LIN YAN ◽  
XIAO-JUN WANG
Keyword(s):  
Vector Meson ◽  
Quark Model ◽  
Chiral Symmetry ◽  
Constituent Quark ◽  
Constituent Quark Model ◽  
Energy Scale ◽  
Meson Theory ◽  
Upper Limit ◽  
Light Vector ◽  
Proper Vertex

We study on-shell decays of light vector meson resonances ρ, K* and ϕ in the framework of chiral constituent quark model using resummation calculations. Such studies are necessary for showing that dynamics described by chiral Lagrangian works well at this energy scale. The effective action is derived by a proper vertex method, where resummation of all orders of momentum expansion is accomplished. Also studied are the loop effects of pseudoscalar meson, which play an important role at this energy scale. The numerical results agree well with the experimental data. A new method to explore the chiral symmetry spontaneously breaking (CSSB) is proposed. It is found that the unitarity of the effective meson theory resulted from resummation derivations demands an upper-limit to the momentum of vector meson. This upper-limit, being critical point, is just the energy scale of CSSB, and is found to be flavor-dependent.

scholarly journals Effective valence quark model and a possible dip in $d\, {\rm Br}(B\to K\ell\bar{\ell})/dq^2$

2014 ◽  
Vol 29 (07) ◽  
pp. 1450040
Author(s):  
Hiroyuki Ishida ◽  
Yoshio Koide
Keyword(s):  
Quark Model ◽  
B Meson ◽  
Valence Quark ◽  
Photon Emission ◽  
Small Region ◽  
Factorization Method ◽  
Quark Propagator ◽  
Final State ◽  
Transition Mechanism ◽  
The Spectator

In rare B meson decays B → Kℓ+ℓ-, a possible contribution of ℓ+ℓ- emission via photon from the "spectator" quark q(q = u, d) in the B meson [Formula: see text] is investigated in addition to the conventional one [Formula: see text]. If such a contribution is sizable compared with the standard estimation of B → Kℓ+ℓ-, we will observe visible difference between dΓ(B0 → K0ℓ+ℓ-)/dq2 and dΓ(B+ → K+ℓ+ℓ-)/dq2 in q2 dependence [Formula: see text]. Besides, as a result of the interference between the conventional one and a new one, a dip appears in dΓ(B → Kℓ+ℓ-)/dq2 at a small region of q2. The interference effect in the B0 decay will also be observed differently from that in the B+ decay. The calculation is done based on a semiclassical approach, a valence quark model. In the present model, the photon emission from the spectator quark q, d → d+γ(u → u+γ) is independent of the b–s transition mechanism, and the characteristic results are due to a straightforward estimate of the quark propagator which cannot be incorporated into the factorization method. The model is not a valence quark "dominant" model, so that, for example, the valence quarks in the final state carry only 24% of the energy–momentum of the kaon.

scholarly journals A comprehensive study on the semileptonic decay of heavy flavor mesons

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Lu Zhang ◽  
Xian-Wei Kang ◽  
Xin-Heng Guo ◽  
Ling-Yun Dai ◽  
Tao Luo ◽  
...  
Keyword(s):  
Vector Meson ◽  
Quark Model ◽  
Semileptonic Decay ◽  
Branching Fraction ◽  
Form Factors ◽  
Good Control ◽  
New Physics ◽  
Mean Value ◽  
Heavy Flavor ◽  
Final State

Abstract The semileptonic decay of heavy flavor mesons offers a clean environment for extraction of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements, which describes the CP-violating and flavor changing process in the Standard Model. The involved form factors where the dynamical information is encoded play an essential role in achieving any conclusive statement. That is, the knowledge of the form factors should be under good control, requiring one to examine more observables in addition to the branching fraction. In this paper, we provide the mean value and the q2-dependent shape for further observables [differential decay distribution (dΓ/dq2), forward-backward asymmetry $$ \left({\mathcal{A}}_{FB}^{ls}\right) $$ A FB ls , longitudinal $$ \left({P}_L^l\right) $$ P L l and transverse $$ \left({P}_T^l\right) $$ P T l polarization of a charged lepton, longitudinal polarization of a vector meson in the final state $$ \left({F}_L^l(V)\right) $$ F L l V , leptonic convexity parameter $$ \left({C}_F^l\right) $$ C F l , and trigonometric moments $$ \left({W}_i^l\right) $$ W i l in the decay of D(s) and B(s) to P/Vl+νl (l = e, μ or τ)], based on the predictions of the relevant form factors from the covariant light-front quark model. P and V denote the pseudoscalar and vector meson, respectively. As a comparison, we find a good agreement with the results from the covariant confining quark model and the relativistic quark model in the literature. As it has been observed that the $$ {P}_L^l $$ P L l and $$ {F}_L^l(V) $$ F L l V are crucial quantities to discriminate various New Physics models, the reexamination of these observables from a different method is also essential and necessary.

scholarly journals THE ELECTRIC AND MAGNETIC FORM FACTORS OF THE NEUTRON

1993 ◽  
Vol 08 (22) ◽  
pp. 2135-2140 ◽  
Author(s):  
FELIX SCHLUMPF
Keyword(s):  
Wave Function ◽  
Vector Meson ◽  
Quark Model ◽  
Constituent Quark ◽  
Sum Rules ◽  
Form Factors ◽  
Constituent Quark Model ◽  
Specific Form ◽  
Vector Meson Dominance ◽  
Magnetic Form Factors

We derive the electric and magnetic form factors of the neutron in the framework of a relativistic constituent quark model. Our parameter free prediction agrees well with a recent, accurate measurement. The relativistic features of the model and the specific form of the wave function are essential for the result. Comparisons are made to other models based on vector meson dominance, perturbative QCD and QCD sum rules.

scholarly journals Quark model calculations of transition form factors at high photon virtualities

2020 ◽  
Vol 241 ◽  
pp. 02007
Author(s):  
G. Ramalho
Keyword(s):  
Momentum Transfer ◽  
Quark Model ◽  
Degrees Of Freedom ◽  
Valence Quark ◽  
Form Factors ◽  
Large Momentum ◽  
Transition Form ◽  
Model Calculations ◽  
Helicity Amplitudes ◽  
Covariant Quark Model

We present calculations of γ*N → N* transition form factors, where N is the nucleon and N* is a nucleon resonance, based on a covariant quark model. Our main focus is at high photon virtualities (large Q2) where the valence quark degrees of freedom dominate the contributions to the transition form factors and helicity amplitudes. In that regime, the quark model estimates can be compared with the available data, particularly with the Jefferson Lab data at intermediate and large momentum transfer (Q2 > 2 GeV2). The main focus is on the Δ(1232)3/2+, N(1440)1/2+, N(1535)1/2- and N(1520)3/2- resonances, but estimates for other higher mass resonances are also discussed.

scholarly journals Covariant nucleon electromagnetic form factors from the Goldstone-boson-exchange quark model

2001 ◽  
Vol 511 (1) ◽  
pp. 33-39 ◽  
Author(s):  
R.F. Wagenbrunn ◽  
S. Boffi ◽  
W. Klink ◽  
W. Plessas ◽  
M. Radici
Keyword(s):  
Quark Model ◽  
Goldstone Boson ◽  
Form Factors ◽  
Electromagnetic Form Factors ◽  
Boson Exchange
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