A phenomenological scaling property of the LHC proton-proton elastic scattering cross sections at moderate transfer momentum has been recently observed. The theoretical QCD saturation framework for hard elastic scattering on the proton, which we recall, predicts a strikingly similar scaling property in the same configuration of energy and momentum transfer. This similarity favors a theoretical interpretation where the hard amplitude is the building block of the $pp$ amplitude via unitarization. The values of the scaling exponents favor two QCD saturation approaches where the saturation scale exponent is of order one half of that which is found for hard elastic scattering and deep inelastic processes on the proton.
We present the unified description of the existing data on elastic small angle $pp$ and $p \bar p$ scattering at the energies 1.8, 1.96, 2.76, 7, 8 and 13~TeV in the framework of Additive Quark Model. The agreement with the data is quite reasonable.
A recent Schwinger Generating Functional based formulation, by H.M.Fried,Y.Gabellini,T.Grandou and Y-M.Sheu and P.H.Tsang provided gauge-invariant, exact, non-perturbative solutions for QCD. After choosing a renormalization scheme and assuming a simpler 2 body quark-quark scattering problem, this formalism is tested against experimental elastic proton-proton scattering at LHC energies (7, 8, 13 TeV). This formulation was previously compared with ISR energies at (23.5 - 62.5 GeV). The full scattering amplitude with infinite gluons summed, infinite loops summed and their interference terms are n…
The TOTEM Collaboration has measured the differential cross section of elastic proton-proton scattering $\mathrm{d}σ/\mathrm{d}|t|$ at $\sqrt{s} = 2.76$, 7, 8, and 13 TeV. It is observed that all $\mathrm{d}σ/\mathrm{d}|t|$ data points vary in the same way as a function of the center-of-mass energy in the so-called "dip" and "bump" regions. These features hint at possible universal properties of elastic scattering. Based on these empirical observations, and taking inspiration from saturation models, we propose a simple scaling law for proton-proton elastic scattering at LHC energies. We find t…
We review elastic and diffractive scattering of protons (called also "forward physics") with emphasis on the LHC data, especially those deviating from the expectations based on extrapolations from earlier measurements at the ISR, Fermilab and thus triggering searches for new ideas, models and theories. We list these new data and provide a brief introduction of available theoretical approaches, mainly those based on analyticity, crossing symmetry and unitarity, particularly the Regge-pole model realizing these concepts. Fits to the data are presented and tensions between theoretical predictions…
Determination of the forward slope in $p~p$ and $\bar p~p$ elastic scattering up to LHC energy
在分析$p p$（或$\bar p p$）弹性微分截面的实验数据时，习惯上以$\exp{(-b|t|)}$的形式定义平均向前斜率$b$，其中$t$是动量传递。以Tevatron和SPS的实验结果为例，我们将借助碰撞图像方法表明，这种简化的假设隐藏了复杂的非翻转散射振幅的有趣信息，并且斜率$b$不是常数。我们调查这个斜率参数的变化，包括一个模型独立的方式来提取这些信息的弹性微分截面的准确测量。我们的结果的扩展到大型强子对撞机的能量域，在未来的实验。
Inspired by the new TOTEM data on elastic $pp$ scattering at 13 TeV, we study the possibility to describe all the diffractive collider data ($σ_{\rm tot}, dσ_{\rm el}/dt$, $ρ\equiv$Re$A$/Im$A$, \sd) in a wide interval of energy (0.0625 to 13 TeV) in the framework of a two-channel eikonal model. We show that a satisfactory description can be achieved without an odd-signature (Odderon) exchange contribution. We consider the possible role of the QCD Odderon which may improve the description of $ρ$ and discuss the importance of the odd-signature term if the amplitude were to exceed the black disc …
Recent measurements of the differential cross sections in the forward region of pp elastic scattering at 7 and 8 TeV show precise form of the $t$ dependence. We propose a detailed analysis of these measurements including the structures of the real and imaginary parts of the scattering amplitude. A good description is achieved, confirming in all experiments the existence of a zero in the real part in the forward region close to the origin, in agreement with the prediction of a theorem by A. Martin, with important role in the observed form of $dσ/dt$. Universal value for the position of this zer…
The $J/ψ$ production originating from elastic and inelastic photoproduction processes in p-p collisions at LHC energies is investigated, where the fragmentation processes are involved. An exact treatment is performed, which adopts the Martin-Ryskin method to weight the contribution from different channels, and can return to Weizsäcker-Williams approximation (WWA) when $Q^{2}\rightarrow0$. The relevant kinematical relations are also achieved. We present a comprehensive analysis for the feature of WWA by comparing with the exact treatment. The results are expressed in $Q^{2}$, $y$, $z$, $p_{T}$,…
The soft diffraction phenomena in the elastic proton-proton scattering are reviewed from the viewpoint of experiments at the LHC (TOTEM and ATLAS collaboration). In the framework of the High Energy Generalized Structure (HEGS) model the form of the diffraction minimum in the nucleon-nucleon elastic scattering in a wide energy region is analyzed. The energy dependences of the main characteristics of the diffraction dip are obtained. The numerical predictions at LHC energies are presented. The comparison of the model predictions with the new LHC data at $\sqrt{s}=13$ TeV is made.
Implications of the recent measurements of the parameter $ρ(s)$ (ratio of the real to imaginary parts of the forward scattering elastic amplitude) by TOTEM collaboration at $\sqrt{s}=13$ $TeV$ are discussed with emphasis on the rising energy dependence of the ratio of elastic to total cross--sections.
The unitarily extended Bialas-Bzdak model of elastic proton-proton scattering is applied, without modifications, to describe the differential cross-section of elastic proton-antiproton collisions in the TeV energy range, and to extrapolate these differential cross-sections to LHC energies. In this model-dependent study we find that the differential cross-sections of elastic proton-proton collision data at 2.76 and 7 TeV energies differ significantly from the differential cross-section of elastic proton-antiproton collisions extrapolated to these energies. The elastic proton-proton differential…
