We present a study of exclusive production of $π^{0}$ meson in proton-proton collisions at high energies. Both diffractive bremsstrahlung (Drell-Hiida-Deck type model), photon-photon, photon-omega and photon-odderon exchange mechanisms are included in the calculation. The $π^{0}$-bremsstrahlung contribution dominates at large (forward, backward) pion rapidities and contributes at small $π^0 p$ invariant mass and could be therefore misinterpreted as the Roper resonance $N^{*}(1440)$. Large cross sections of the order of mb are predicted. We predict strong dependence of the slope in $t$ (squared four-momentum transfer between ingoing and outgoing proton) on the mass of the supplementary excited $π^{0} p$ system. At high energy and midrapidity, the photon-photon contribution dominates over the diffractive components, however, the corresponding cross section is rather small. The photon-odderon and odderon-photon contributions are included in addition and first estimates (upper limits) of their contributions are presented. We suggest a search for the odderon contribution at midrapidity and at $p_{\perp,π^{0}} \sim$ 0.5 GeV. Our predictions are ready for verification at LHC. The bremsstrahlung mechanisms discussed here contribute also to the $pp \to p(n π^{+})$ reaction. Both channels give a sizable contribution to the low-mass single diffractive cross section and must be included in extrapolating the measured experimental single diffractive cross section.
The charged particle multiplicity distribution in high energy hadronic and nuclear collisions receive contribution from both diffractive and non diffractive processes. It is experimentally challenging to segregate diffractive events from non-diffractive events. The present work aims to separate and extract the charged particle multiplicity distribution of diffractive and non-diffractive events in hadronic collisions at LHC energies. A data driven model using the topic modelling statistical tool, DEMIX, has been used to demonstrate the proof of concept for p p collisions at 7 TeV generated by P…
Exclusive diffractive photon bremsstrahlung at high energies
我们讨论的$p p \to p p γ$反应在大型强子对撞机。我们考虑衍射的经典韧致辐射机制,包括质子的非点状性质的影响。此外,我们首次考虑了(矢量介子)-坡密子、光子-π介子以及光子-坡密子交换过程。积分衍射韧致辐射截面($E_γ>100$ GeV)仅为$μ$ b的量级。我们试图确定区域的相空间的机制之一占主导地位。经典的韧致辐射占主导地位,在大的前向/后向光子的赝快度,接近散射质子的赝快度。相比之下,光子-坡密子(坡密子-光子)机制在中等速度下占主导地位,但相关的截面相当小。相比之下,虚拟Ω-再散射机制在较小的光子角度(较大的光子速率)下起作用。
The exclusive reaction $pp \to pp (K^{*0} \bar{K}^{*0} \to K^{+}π^{-}K^{-}π^{+})$ for the LHC experiments is discussed. The amplitudes for the reaction are formulated within the tensor-pomeron approach. We consider two diffractive mechanisms: the $f_{2}(1950)$ $s$-channel exchange mechanism and the $K^{*0}$-exchange mechanism. First mechanism is a candidate for central diffractive production of tensor glueball and the second one is an irreducible continuum. Comparison with data from WA102 experiment are made and predictions for LHC experiments are given. We find that including the continuum co…
本文在未积分胶子分布函数(UGDF)的形式下讨论了在$pp \to p X p$反应中$η'$和$η_c$介子的双衍射(双弹性)产生。估计了$γ^* γ^* \to η'$融合的贡献。计算并讨论了Feynman $x_F$(或快度)中的分布,初始质子和末态质子之间的转移四动量平方($t_1$,$t_2$)和出射质子之间的方位角差($Φ$)。并将计算结果与WA102资料进行了比较。在更高的能量的预测。
In this paper we consider the Good - Walker approach for the diffractive excitation and updated the Miettinen -- Pumplin (MP) model for $pp/\bar{p}p$ collisions considering the recent LHC data for the total and elastic $pp$ cross sections. The behavior of the total, elastic and diffractive cross sections is analyzed and predictions for the energies of Run 3 of the LHC and those of the Cosmic Rays experiments are derived. Our results demonstrate that the MP model is able to describe the current data and that it implies that the cross section for the diffraction excitation in $pp$ collisions is …
Diffractive Double-Elastic Production of $η$' and $η_c$ in the $p p \to p X p$ Reaction
本文在未积分胶子分布函数(UGDF)的形式下讨论了在$pp \to p X p$反应中$η'$和$η_c$介子的双衍射(双弹性)产生。估计了$γ^* γ^* \to η'$融合的贡献。计算并讨论了Feynman $x_F$(或快度)中的分布、质子转移四动量平方($t_1$,$t_2$)和质子出射方位角差($Φ$)。并将计算结果与WA102资料进行了比较。在更高的能量的预测。
Exclusive $p p \to p p π^{0}$ reaction at high energies
详细讨论了适用于高能量的$p p \to p p π^{0}$过程的振幅。衍射韧致辐射(Drell-Hiida-Deck型模型),光子-光子和光子-ω交换机制都包括在计算中。预测了mb量级的大截面。计算了RHIC和LHC能区质子和π介子的快度和横动量的微分截面以及出射质子之间的相对方位角。强子韧致辐射的贡献在大的(前向,后向)π介子快度下占主导地位。衍射非共振背景在小的$π^0 p$不变质量下有贡献,因此可能被误解为罗珀共振。我们预测强烈的依赖性的斜率在$t$(平方四动量转移之间的进出质子)的补充激发$π^{0}p$系统的质量。在高能量和中等速度下,光子-光子贡献在衍射分量上占主导地位,然而,相应的截面相当小。此外,还包括光子-odderon和odderon-光子的贡献,并给出了它们对中性π介子快度和横动量分布的贡献的初步估计(上限)。我们建议在中快度和$p_{\perp,π^{0}} \sim$ 0.5 GeV的odderon贡献的搜索。我们的预测已经准备好在RHIC和LHC上进行验证。这里讨论的韧致辐射机制也有助于$pp \to p(n π^{+})$反应。这两个通道都对低质量单衍射截面有相当大的贡献,必须包括在外推测得的实验单衍射截面中。
We present first predictions of the cross sections and differential distributions for the exclusive reaction $pp \to pp K^{*0} \bar{K}^{*0}$ contributing to the $K^{+} K^{-} π^{+} π^{-}$ channel. The amplitudes for the reaction are formulated within the nonperturbative tensor-pomeron approach. We consider separately the $f_{2}(1950)$ $s$-channel exchange mechanism and the $K^{*0}$ $t/u$-channel exchange mechanism, focusing on their specificities. First mechanism is a candidate for the central diffractive production of tensor glueball and the second one is an irreducible continuum. We adjust pa…
We propose a new model for a homogeneous description of hadron-hadron and hadron-nucleus collisions, the Gluon Exchange Model, fundamentally based on color octet (gluon) exchange. In proton-proton collisions we provide an exact description of the final state proton and neutron spectrum including the proton diffractive peak. In proton-nucleus reactions we find that the projectile proton diquark cannot survive in more than about half of multiple proton-nucleon processes and consequently must be very frequently disintegrated, leading to long transfers of baryon number over rapidity space.
A model for exclusive diffractive resonance production in proton-proton collisions at high energies is presented. This model is able to predict double differential distributions with respect to the mass and the transverse momentum of the produced resonance in the mass region $\sqrt{M^2}\le$5 GeV. The model is based on convoluting the Pomeron distribution in the proton with the Pomeron-Pomeron-meson total cross section. The Pomeron-Pomeron-meson cross section is saturated by direct-channel contributions from the Pomeron as well as from two different $f$ trajectories, accompanied by the isolated…