اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدQCD Sum Rule for S_{11}(1535)
69
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We propose a new interpolating field for S$_{11}$(1535) to determine its mass from QCD sum rules. In the nonrelativistic limit, this interpolating field dominantly reduces to two quarks in the s-wave state and one quark in the p-wave state. An optimization procedure, which makes use of a duality relation, yields the interpolating field which overlaps strongly with the negative-parity baryon and at the same time does not couple at all to the low lying positive-parity baryon. Using this interpolating field and applying the conventional QCD sum rule analysis, we find that the mass of S$_{11}$ is reasonably close to the experimentally known value, even though the precise determination depends on the poorly known quark-gluon condensate. Hence our interpolating field can be used to investigate the spectral properties of S$_{11}$(1535).
قيم البحث
اقرأ أيضاً
The Fubini-Furlan-Rossetti sum rule for pion photoproduction on the nucleon is evaluated by dispersion relations at constant t, and the corrections to the sum rule due to the finite pion mass are calculated. Near threshold these corrections turn out
to be large due to pion-loop effects, whereas the sum rule value is closely approached if the dispersion integrals are evaluated for sub-threshold kinematics. This extension to the unphysical region provides a unique framework to determine the low-energy constants of chiral perturbation theory by global properties of the excitation spectrum.
We derive a new QCD sum rule for $D(0^+)$ which has only the $Dpi$ continuum with a resonance in the hadron side, using the assumption similar to that has been successfully used in our previous work to the mass of $D_s(0^+)(2317)$. For the value of t
he pole mass $M_c=1.38 $ GeV as used in the $D_s(0^+)$ case we find that the mass of $D(0^+)$ derived from this sum rule is significantly lower than that derived from the sum rule with the pole approximation. Our result is in agreement with the experimental dada from Belle.
New cross sections for the reaction $ep to eeta p$ are reported for total center of mass energy $W$=1.5--2.3 GeV and invariant squared momentum transfer $Q^2$=0.13--3.3 GeV$^2$. This large kinematic range allows extraction of new information about re
sponse functions, photocouplings, and $eta N$ coupling strengths of baryon resonances. A sharp structure is seen at $Wsim$ 1.7 GeV. The shape of the differential cross section is indicative of the presence of a $P$-wave resonance that persists to high $Q^2$. Improved values are derived for the photon coupling amplitude for the $S_{11}$(1535) resonance. The new data greatly expands the $Q^2$ range covered and an interpretation of all data with a consistent parameterization is provided.
Using general baryon interpolating fields $J_B$ for $B= N, Xi, Sigma, $ without derivative, we study QCD sum rules for meson-baryon couplings and their dependence on Dirac structures for the two-point correlation function with a meson $iint d^4x e^{i
qx} bra 0|{rm T}[J_B(x)bar{J}_B(0)] |{cal M}(p)ket$. Three distinct Dirac structures are compared: $igamma_5$, $igamma_5fslash{p}$, and $gamma_5sigma_{mu u}q^mu p^ u$ structures. From the dependence of the OPE on general baryon interpolating fields, we propose criteria for choosing an appropriate Dirac structure for the coupling sum rules. The $gamma_5sigma_{mu u}q^mu p^ u$ sum rules satisfy the criteria while the $igamma_5$ sum rules beyond the chiral limit do not. For the $igamma_5fslash{p}$ sum rules, the large continuum contributions prohibit reliable prediction for the couplings. Thus, the $gamma_5sigma_{mu u}q^mu p^ u$ structure seems pertinent for realistic predictions. In the SU(3) limit, we identify the OPE terms responsible for the $F/D$ ratio. We then study the dependence of the ratio on the baryon interpolating fields. We conclude the ratio $F/D sim 0.6-0.8$ for appropriate choice of the interpolating fields.
Within a relativistic single particle model, we calculate the Coulomb sum rule of inclusive electron scattering from $^{40}$Ca and $^{208}$Pb in quasielastic region. Theoretical longitudinal and transverse structure functions are extracted for three
momentum transfers from 300 to 500 MeV/c and compared with the experimental data measured at Bates and Saclay. We find that there is no drastic suppression of the longitudinal structure function and that the Coulomb sum rule depends on nucleus in our theoretical model.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
