4 pages, 3 figures, to appear in the proceedings of 14th High-Energy Physics International Conference in Quantum Chromodynamics (QCD 08), Montpellier, France, 7-12 Jul 2008
Hunting resonance poles with Rational Approximants
基于数学上定义良好的Padé理论,提出了一种理论上安全的提取极点质量和共振宽度的新方法。特别地,由于Montessus de Ballore定理,我们能够展开振幅的第二黎曼单,以搜索复平面中谐振极点的位置。该方法是系统的,并提供了一个独立于模型的处理的预测和相应的近似误差。这封信部分涵盖了作者在2010年6月28日至7月3日在法国蒙彼利埃举行的第15届国际量子色动力学会议:QCD 10(25周年纪念)和2010年8月30日至9月3日在西班牙马德里举行的夸克禁闭和强子谱IX上提交的材料。
We separate the contributions of parton distributions from higher twist corrections to the deeply inelastic lepton-proton scattering in the resonance region using the Jefferson Lab data at low $Q^2$. The study indicates that the concept of the valence quarks and their distributions are indispensable even at $Q^2<1GeV^2$. The quark-hadron duality is also discussed.
Influence of the re-scattering process on polarization observables in reaction gamma + d --> p + p + pi- in Delta - resonance region
本文研究了π-核子和核子-核子再散射效应对δ-等压线区γ + d = p + p + π-反应极化观测值的影响。用图解法研究了π-核子和核子-核子的再散射。相对论不变形式的π介子光生和π介子核子散射运营商使用。在K-矩阵方法中的么正化过程被应用于共振分振幅。它示出了一个相当大的影响的再散射效应的极化观测值的反应中的Delta共振区的大动量的最后质子。
The resonances, containing $c\bar c$ plus $s\bar s$ (or light $q\bar q$) quarks in the mass region $(3900-4700)$ MeV, are analyzed in the relativistic strong coupling theory, with and without channel coupling phenomena. The conventional charmonium spectrum is presented, being calculated with the relativistic string Hamiltonian, which does not contain fitting parameters, while for high excitations the universal flattened confining potential is used. It is shown that $X(4274),X(4500),X(4700)$ can be identified as $3\,^3P_1, 4\,^3P_0, 5\,^3P_0$ states. The exotic states are considered using the c…
We investigate the implications of a putative new resonance in the TeV region coupled to the weak bosons. By studying perturbative unitarity in longitudinal WW scattering, we find that a weakly coupled spin-1 resonance, that explains the ATLAS diboson excesses, is allowed with a SM-like Higgs. On the other hand, larger values of the resonance couplings, preferred in models of strong dynamics, would imply either sizeable reduction of the Higgs couplings or new physics, beyond the diboson resonance, at a few TeV.
Compton scattering off the proton in the third resonance region is analyzed for the first time, owing to the full combined analysis of pion- and photo-induced reactions in a coupled-channel effective Lagrangian model with K-matrix approximation. Two isospin $I=3/2$ resonances $D_{33}(1700)$ and $F_{35}(1930)$ are found to be essential in the range of 1.6 - 1.8 GeV. The recent beam asymmetry data of Compton scattering from the GRAAL facility are used to determine the helicity couplings of these resonances, and strong constraints are coming also from $πN$ and $KΣ$ photoproduction data. The possi…
In this work we report the calculation of the total cross section for pion-production by the dispersion of neutrinos on nucleons. We use a consistent formalism for the intermediate resonance states of spin $3/2$ , taking care on the conditions imposed by the invariance on contact transformations and using the Sachs parametrization for the form factors. In addition, we incorporate states in the second resonance region up to 1.6 GeV and implement different approaches for all the dressed resonance propagators. In addition to the $Δ$(1232), we include the N$^*$(1440),N$^*$(1535)and N$^*$(1520) res…
One-loop electroweak corrections to the annihilation cross-sections of dark matter in the Higgs resonance region of the inert doublet model (IDM) are investigated. The procedure of how to implement the width of the Higgs in order to regularise the amplitude both at tree-level and at one-loop together with the renormalisation of a key parameter of the model, are thoroughly scrutinised. The discussions go beyond the application to the relic density calculation and also beyond the IDM so that addressing these technical issues can help in a wider context. We look in particular at the dominant chan…
We study beam-transverse and normal single-spin asymmetry for electron-proton inelastic scattering in the resonance region for the case where a pion is observed in the final state. There is no beam single-spin asymmetry if the observed particle has single-photon exchange as its only interaction, but this is naturally circumvented when one observes a strongly interacting final state particle. The asymmetries are not large as there is an electron mass divided by momentum transfer suppression. We present results for the cases where the final electron and a pion are both observed, with asymmetries…
A study is presented to extend the measurements of photon-photon scattering in ultra-peripheral Pb-Pb collisions at the LHC into the mass region of the pseudoscalar resonances $η$ and $η'$. The elementary photon-photon scattering cross section is presented. The cross section for photon-photon scattering in Pb-Pb is derived by convoluting the elementary photon-photon cross section with the Pb-Pb photon luminosity. The main background to two-photon final states, arising from double $π^{0}$ production with two of the four decay photons escaping detection, is examined, and possible kinematical con…
We investigate emission of the bremsstrahlung photons in the scattering of protons off nuclei at the $Δ$-resonance energy region. Including properties of $Δ$-resonance in the nucleus-target to the bremsstrahlung model, we find the following. (1) Ratio between incoherent emission and coherent emission is about $10^{6}$--$10^{7}$ for $p + \isotope[197]{Au}$ (without $Δ$-resonance) at energy of proton beam $E_{\rm p}$ of 190~MeV, where the calculated full bremsstrahlung spectrum is in good agreement with experimental data. This confirms importance of incoherent processes in study of $Δ$-resonance…
We present our recent efforts to determine the matrix elements associated with the transition between the nucleon and a nucleon resonance induced by the vector current, which are necessary ingredients for models of neutrino-induced reactions in the resonance region. This is accomplished by making the comprehensive analysis of the data for various meson photo- and electro-production reactions off the nucleon within a sophisticated coupled-channels framework, which is known as the ANL-Osaka dynamical coupled-channels model. We also give a brief introduction to our project for constructing a unif…
High precision studies of Beyond-Standard-Model physics through accelerator-based neutrino oscillation experiments require a very accurate description of neutrino-nucleus cross sections in a broad energy region, going from quasielastic scattering up to deep inelastic scattering. In this work we focus on the following processes: quasielastic scattering, two-particle-two-hole excitations, and the excitation of the first (Delta) and second (Roper) resonances of the nucleon. The nuclear model is fully relativistic and includes both one- and two-body currents. We compare our results with recent T2K…