اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStrong coupling constant of negative parity nucleon with $pi$ meson in light cone QCD sum rules
89
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We estimate strong coupling constant between the negative parity nucleons with $pi$ meson within the light cone QCD sum rules. A method for eliminating the unwanted contributions coming from the nucleon--nucleon and nucleon--negative parity nucleon transition is presented. It is observed that the value strong coupling constant of the negative parity nucleon $N^ast N^ast pi$ transition is considerably different from the one predicted by the 3--point QCD sum rules, but is quite close to the coupling constant of the positive parity $N N pi$ transition.
قيم البحث
اقرأ أيضاً
The strong coupling constants of the $pi$ and $K$ mesons with negative parity octet baryons are estimated within the light cone QCD sum rules. It is observed that all strong coupling constants, similar to the case for the positive parity baryons, can
be described in terms of three invariant functions, where two of them correspond to the well known $F$ and $D$ couplings in the $SU(3)_f$ symmetry, and the third function describes the $SU(3)_f$ symmetry violating effects. We compare our predictions on the strong coupling constants of pseudoscalar mesons of negative parity baryons with those corresponding to the strong coupling constants for the positive parity baryons.
Using the most general form of the interpolating current of the baryons, the strong coupling constants of the light vector mesons with the octet baryons are calculated within the light cone QCD sum rules. The SU(3)_f symmetry breaking effects are tak
en into account in the calculations. It is shown that each of the electric and magnetic coupling constants can be described in terms of three universal functions. A detailed comparison of the results of this work on aforementioned couplings with the existing theoretical results is presented.
We use QCD light-cone sum rules to examine the B -> pi pi hadronic matrix element of the current-current operator with c quarks in the penguin topology (``charming penguin) as a potential source of the substantial O(1/m_b) effects. Our results indica
te that charming penguins do not generate sizable nonperturbative effects at finite m_b. The same is valid for the penguin contractions of the current-current operators with light quarks. The dominant penguin topology effects are predicted to be O(alpha_s). Still, the nonperturbative effects at finite m_b can accumulate to a visible effect that is illustrated by calculating the CP-asymmetry in the B^0_d -> pi^+ pi^- decay.
We compute perturbative corrections to $B to pi$ form factors from QCD light-cone sum rules with $B$-meson distribution amplitudes. Applying the method of regions we demonstrate factorization of the vacuum-to-$B$-meson correlation function defined wi
th an interpolating current for pion, at one-loop level, explicitly in the heavy quark limit. The short-distance functions in the factorization formulae of the correlation function involves both hard and hard-collinear scales; and these functions can be further factorized into hard coefficients by integrating out the hard fluctuations and jet functions encoding the hard-collinear information. Resummation of large logarithms in the short-distance functions is then achieved via the standard renormalization-group approach. We further show that structures of the factorization formulae for $f_{B pi}^{+}(q^2)$ and $f_{B pi}^{0}(q^2)$ at large hadronic recoil from QCD light-cone sum rules match that derived in QCD factorization. In particular, we perform an exploratory phenomenological analysis of $B to pi$ form factors, paying attention to various sources of perturbative and systematic uncertainties, and extract $|V_{ub}|= left(3.05^{+0.54}_{-0.38} |_{rm th.} pm 0.09 |_{rm exp.}right) times 10^{-3}$ with the inverse moment of the $B$-meson distribution amplitude $phi_B^{+}(omega)$ determined by reproducing $f_{B pi}^{+}(q^2=0)$ obtained from the light-cone sum rules with $pi$ distribution amplitudes. Furthermore, we present the invariant-mass distributions of the lepton pair for $B to pi ell u_{ell}$ ($ell= mu ,, tau$) in the whole kinematic region. Finally, we discuss non-valence Fock state contributions to the $B to pi$ form factors $f_{B pi}^{+}(q^2)$ and $f_{B pi}^{0}(q^2)$ in brief.
We derive QCD light-cone sum rules for the hadronic matrix elements of the heavy baryon transitions to nucleon. In the correlation functions the $Lambda_c,Sigma_c$ and $Lambda_b$ -baryons are interpolated by three-quark currents and the nucleon distr
ibution amplitudes are used. To eliminate the contributions of negative parity heavy baryons, we combine the sum rules obtained from different kinematical structures. The results are then less sensitive to the choice of the interpolating current. We predict the $Lambda_{b}to p$ form factor and calculate the widths of the $Lambda_{b}to pell u_l$ and $Lambda_{b}to p pi$ decays. Furthermore, we consider double dispersion relations for the same correlation functions and derive the light-cone sum rules for the $Lambda_cND^{(*)}$ and $Sigma_cND^{(*)}$ strong couplings. Their predicted values can be used in the models of charm production in $pbar{p}$ collisions.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
