arXiv subjects

M. D. Scadron

Publications and source records attributed to M. D. Scadron.

At least 37 records · Page 2Linked to original sources

arXiv2001

High-Tc via electron polar coupling: relation to low-Tc superconductivity and to chiral symmetry in particle physics

Directional coupling of Thornber-Feynman polarization with the high-Tc ARPES distribution specifies the optimum flatband pseudogap Δand mobile localized quasiparticle. This coupling peaks by tuning the statistics and interaction energy to produce stable short-ranged directional pairing that reflects the lattice asymmetry. Analogous energy gap and BCS ratio parameters are identified for low-Tc long-range acoustical phonons and for quark-anti-quark tightly bound chiral pions in particle physics.

cond-mat.supr-con↗

arXiv2000

Radiative VPgamma transitions and eta-eta' mixing

A value for the $η$-$η^\prime$ mixing angle is extracted from the data on $VPγ$ transitions using simple quark-model ideas. The set of data covers {\it all} possible radiative transitions between the pseudoscalar and vector meson nonets. Two main ingredients of the model are the introduction of flavour-dependent overlaps for the various $q\bar{q}$ wave functions and the use of the quark-flavour basis to describe the $η$-$η^\prime$ system. In this basis the mixing angle is found to be $ϕ_P=(37.7\pm 2.4)^\circ$.

hep-ph↗

arXiv2000

Hyperon Nonleptonic Weak Decays Revisited

We first review the current algebra - PCAC approach to nonleptonic octet baryon 14 weak decay B (\to) (B^{\prime})(π) amplitudes. The needed four parameters are independently determined by (Ω\to Ξπ),(ΛK) and (Ξ^{-}\to Σ^{-}γ) weak decays in dispersion theory tree order. We also summarize the recent chiral perturbation theory (ChPT) version of the eight independent B (\to) (B^{\prime}π) weak (ΔI) = 1/2 amplitudes containing considerably more than eight low-energy weak constants in one-loop order.

hep-ph↗

arXiv2000

Studying the scale and q^2 dependence of K^+-->pi^+e^+e^- decay

We extract the K^+-->pi^+e^+e^- amplitude scale at q^2=0 from the recent Brookhaven E865 high-statistics data. We find that the q^2=0 scale is fitted in excellent agreement with the theoretical long-distance amplitude. Lastly, we find that the observed q^2 shape is explained by the combined effect of the pion and kaon form-factor vector-meson-dominance rho, omega and phi poles, and a charged pion loop coupled to a virtual photon-->e^+e^- transition.

hep-ph↗

arXiv2000

On the polarization properties of the charmed baryon Lambda^+_c in the Lambda^+_c -> p + K^- + pi^+ + pi^0 decay

The polarization properties of the charmed Lambda^+_c baryon are investigated in weak non-leptonic four-body Lambda^+_c -> p + K^- + pi^+ + pi^0 decay. The probability of this decay and the angular distribution of the probability are calculated in the effective quark model with chiral U(3)XU(3) symmetry incorporating Heavy Quark Effective theory (HQET) and the extended Nambu-Jona-Lasinio model with a linear realization of chiral U(3)XU(3) symmetry. The theoretical value of the probability of the decay Lambda^+_c -> p + K^- + pi^+ + pi^0 relative to the probability of the decay Lambda^+_c -> p + K^- + pi^+ does not contain free parameters and fits well experimental data. The application of the obtained results to the analysis of the polarization of the Lambda^+_c produced in the processes of photo and hadroproduction is discussed.

hep-ph↗

arXiv2000

On the reactions p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds

The cross sections for the reactions of the strange production p + p -> p + Lambda + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds of the final states p Lambda K^+ and p Sigma^0 K^+ are calculated in the effective Lagrangian approach. Our approach is based on the dominant contribution of the one-pion exchange and strong interaction of the colliding protons in the initial state. The theoretical values of the cross sections agree reasonably well with the experimental data. The polarization properties of the Lambda and Sigma^0 hyperons are discussed.

hep-ph↗

arXiv2000

Quark level linear σmodel (LσM) via loop graphs

First, the LσM is nonperturbatively solved via loop-order gap equations. Then the Nambu-Goldstone theorem (NGT) is expressed in LσM language. Next, the Lee null tadpole sum for this SU(2) LσM theory is shown to require N_c = 3. Then LσM s-wave chiral cancellations are studied in tree-and in loop-order. Also, vector meson dominance (VMD) is shown to follow from this LσM. Next, the scalar nonet is studied in the infinite momentum frame (IMF). Finally, the LσM is suggested as the infrared limit of nonperturbative QCD.

hep-ph↗

arXiv2000

Revisiting the U_A(1) problems

We survey various U_A(1) problems and attempt to resolve the two puzzles related to the eta mesons that have experimental verification. Specifically, we first explore the Goldstone structure of the eta and eta' mesons in the context of eta-eta' mixing using ideas based on QCD. Then we study the eta decays eta->3pi0, eta'->3pi0 and eta'->eta pi pi. Finally we arrive at essentially the same picture in the dynamical scheme based on consistently coupled Schwinger-Dyson and Bethe-Salpeter integral equations. This chirally well-behaved bound-state approach clarifies the distinction between the usual axial-current decay constants and the gamma gamma decay constants in the eta-eta' complex. Allowing for the effects of the SU(3) flavor symmetry breaking in the quark-antiquark annihilation, leads to the improved eta-eta' mass matrix.

hep-ph↗

arXiv2000

Chiral Shielding

We demonstrate how a chiral soft pion theorem (SPT) shields the scalar meson ground state isoscalar $σ(600-700)$ and isospinor $κ(800-900)$ from detection in $a_{1}\toπ(ππ)_{\mathrm{swave}}$, $γγ\to2π^{\circ}$, $π^{-}p\toπ^{-}π^{+}n$ and $K^{-}p\to K^{-}π^{+}n$ processes. While pseudoscalar meson PVV transitions are known to be determined by (only) quark loop diagrams, the above SPT also constrains scalar meson SVV transitions to be governed (only) by meson loop diagrams. We apply this latter SVV theorem to $a_{0}\toγγ$ and $f_{0}\toγγ$ decays.

hep-ph↗

arXiv1999

Kaon Weak Decays in Chiral Theories

The ten nonleptonic weak decays $K \to 2π$, $K \to 3π$, $K_L \to 2γ$, $K_S \to 2γ$, $K_L \to π^\circ 2γ$, are predicted for a chiral pole model based on the linear sigma model theory which automatically satisfies the partial conservation of axial current (PCAC) hypothesis. These predictions, agreeing with data to the 5% level and containing no or at most one free parameter, are compared with the results of chiral perturbation theory (ChPT). The latter ChPT approach to one-loop level is known to contain at least four free parameters and then predicts a $K_L \to π^\circ γγ$ rate which is 60% shy of the experimental value. This suggests that ChPT is an unsatisfactory approach towards predicting kaon weak decays.

hep-ph↗

arXiv1999

Pion Interactions in Chiral Field Theories

We study in various chiral models the pion charge radius, $π_{e3}$ form factor ratio, $π^\circ \to γγ$ amplitude, charge pion polarizabilities, $γγ\to π^\circ π^\circ$ amplitude at low energies and the $ππ$ s-wave I = 0 scattering length. We find that a quark-level linear sigma-model approach (also being consistent with tree-level vector meson dominance) is quite compatible with all of the above data.

hep-ph↗

arXiv1999

Meson PVV Interactions are determined by Quark Loops

We show that all abnormal parity three-body meson interactions can be adequately described by quark loops, evaluated at zero external momentum, with couplings determined by $U(N_f)$ symmetry. We focus primarily on radiative meson decays which involve one pseudoscalar. The agreement with experiment for non-rare decays is surprisingly good and requires very few parameters, namely the coupling constants $g_{πqq}$ and $g_{ρqq}$ and some mixing angles. This agreement extends to some three-body decays that are dominated by pion pairs in a P-wave state.

hep-ph↗

arXiv1999

The omega to rho pi transition and omega to rho 3 pi decay

We evaluate the omega to rho pi transition and the omega to 3 pi decay using a Quark Level Linear Sigma Model ($QLσM$). We obtain $g^{QLσM}_{ωρπ}= (10.33 - 14.75) GeV^{-1}$ to be compared with other model dependent estimates averaging to $g_{ωρπ} = 16 GeV^{-1}$. We show that in the $QLσM$ a contact term is generated for the $ω\to 3 π$ decay. Although the contact contribution by itself is small, the interference effects turn out to be important.

hep-ph↗

arXiv1998

Nontriviality of the Linear Sigma Model

We consider techniques (based on an ultraviolet cutoff) used to prove that the pure boson ($ϕ^4)_4$ field theory is trivial and apply them instead to the dynamically generated quark-level linear sigma model. This cutoff approach leads to the conclusion that the latter field theory is in fact nontrivial.

hep-ph↗

arXiv1998

Vector Meson Dominance and Rho-Omega Mixing

The scale of a phenomenologically successful charge-symmetry-violating nucleon-nucleon interaction, that attributed to meson exchange with a $ΔI =1$ rho-omega transition, is set by the Coleman-Glashow SU(2) breaking tadpole mechanism. A single tadpole scale has been obtained from symmetry arguments, electromagnetic meson and baryon measured mass splittings, and the observed isospin violating ($ΔI=1$) decay $ω\to π^+π^-$. The hadronic realization of this tadpole mechanism lies in the $I = 1$ $a_0$ scalar meson. We show that measured hadronic and two-photon widths of the $a_0$ meson, with the aid of the Vector Meson Dominance model, recover the universal Coleman-Glashow tadpole scale.

nucl-th↗

arXiv1998

Regularizing the quark-level $σ$ model

We show that the finite difference, $-iπ^2 m^2$, between quadratic and logarithmic divergent integrals $\int d^4p[m^2(p^2-m^2)^{-2}-(p^2-m^2)^{-1}]$, as encountered in the linear $σ$ model, is in fact regularization independent.

hep-ph↗

arXiv1998

Dynamical Generation of Linear $σ$ model SU(3) Lagrangian and Meson Nonet Mixing

This paper is the SU(3) extension of the dynamically generated SU(2) linear $σ$ model Lagrangian worked out previously using dimensional regularization. After discussing the quark-level Goldberger-Treiman relations for SU(3) and the related gap equations, we dynamically generate the meson cubic and quartic couplings. This also constrains the meson-quark coupling constant to $g=2π/\sqrt3$ and determines the SU(3) scalar meson masses in a Nambu-Jona-Lasinio fashion. Finally we dynamically induce the U(3) pseudoscalar and scalar mixing angles in a manner compatible with data.

hep-ph↗

arXiv1998

The $η- η'$ Mixing Angle Revisited

The value of the $η- η'$ mixing angle $θ_P$ is phenomenologically deduced from a rather exhaustive and up-to-date analysis of data including strong decays of tensor and higher-spin mesons, electromagnetic decays of vector and pseudoscalar mesons, $J/ψ$ decays into a vector and a pseudoscalar meson, and other transitions. A value of $θ_P$ between $-17^\circ$ and $-13^\circ$ is consistent with all the present experimental evidence and the average $θ_P=-15.5^\circ\pm 1.3^\circ$ seems to be favoured.

hep-ph↗