We discuss recent calculations of the survival probability of the large rapidity gaps in exclusive processes of the type pp --> p+A+p at high energies. Absorptive or screening effects are important, and one consequence is that the total cross section at the LHC is predicted to be only about 90 mb.
We study the probability for no jets with transverse momenta above a given cut to be found in the rapidity region between two high pT jets with a large rapidity separation. Our investigation uses the parton shower event generator DEDUCTOR with color beyond the leading-color-plus approximation included perturbatively.
We apply the phenomenological Reggeon field theory framework to investigate rapidity gap survival (RGS) probability for diffractive dijet production in proton-proton collisions. In particular, we study in some detail rapidity gap suppression due to elastic rescatterings of intermediate partons in the underlying parton cascades, described by enhanced (Pomeron-Pomeron interaction) diagrams. We demonstrate that such contributions play a subdominant role, compared to the usual, so-called "eikonal", rapidity gap suppression due to elastic rescatterings of constituent partons of the colliding proton…
Energy dependence of the survival probability of large rapidity gap
在假定高斯不透明度的Eikonal模型中计算了大快度能隙(LRG)$< \mid S \mid^2 >$的生存概率与能量的关系。确定$< \mid S \mid^2 >$的参数直接从实验数据中进行评估,而无需进一步求助于模型。我们发现,$< \mid S \mid^2 >$随着能量的增加而减少,与最近的结果在Tevatron的LRG dijet生产。
本文总结了TeV能量下强相互作用的黑盘机制(BDR)如何影响纯硬衍射pp -> p + H + p(H = dijet,Qbar-Q,Higgs)中快度能隙的生存。采用最近开发的部分子描述这样的过程中,我们讨论(a)在小碰撞参量的衍射抑制软旁观者相互作用的BDR;(b)进一步抑制硬旁观者部分子的非弹性相互作用的BDR;(c)硬和软相互作用之间的相关性。硬观众的相互作用大大降低了在LHC能量的快度间隙生存概率相比,以前报道的估计。
Rapidity gap survival in central exclusive diffraction: Dynamical mechanisms and uncertainties
本文总结了我们对中心排他衍射pp -> p + H + p(H =大质量系统)中快度间隙生存的动力学机制的理解,并讨论了目前生存概率估计的不确定性。衍射散射的主要抑制是由于在小PP碰撞参量下的非弹性软旁观者相互作用,并且可以在平均场近似(独立的硬和软相互作用)中描述。适度的额外抑制来自碰撞质子的部分子组态的涨落。在LHC能量下,与gg -> H过程相关的硬旁观者部分子的吸收相互作用达到了黑盘区,并引起了大量的额外抑制,使生存概率低于0.01。
本文总结了TeV能量下强相互作用的黑盘机制(BDR)如何影响纯硬衍射pp--> p + H + p(H =dijet,\bar Q Q,Higgs)中快度能隙的生存。采用最近开发的部分子描述这样的过程中,我们讨论(a)在小碰撞参量的衍射抑制软旁观者的相互作用在BDR;(b)进一步抑制硬旁观者部分子在BDR的非弹性相互作用;(c)硬和软相互作用之间的相关性的影响,建议由各种模型的质子结构(颜色波动,部分子的空间相关性)。硬观众的相互作用在BDR大幅降低在LHC能量的快度间隙生存概率相比,以前报道的估计。
Observations of rare processes containing large rapidity gaps at high energy colliders may be exceptionally informative. However the cross sections of these events are small in comparison with that for the inclusive processes since there is a large probability that the gaps may be filled by secondary particles arising from additional soft interactions or from gluon radiation. Here we review the calculations of the probability that the gaps survive population by particles from these effects for a wide range of different processes.
We discuss an application of dynamical multi-parton interaction model, tuned to measurements of underlying event topology, for a description of destroying rapidity gaps in the jet-gap-jet processes at the LHC. We concentrate on the dynamical origin of the mechanism of destroying the rapidity gap. The cross section for jet-gap-jet is calculated within LL BFKL approximation. We discuss the topology of final states without and with the MPI effects. We discuss some examples of selected kinematical situations (fixed jet rapidities and transverse momenta) as distributions averaged over the dynamics …
In this paper we discuss the example of one rapidity gap process: the inclusive cross sections of the leading neutrons in deep inelastic scattering with protons (DIS). The equations for this process are proposed and solved, giving the example of theoretical calculation of the survival probability for one rapidity gap processes. It turns out that the value of the survival probability is small and it decreases with energy
In this paper we present a self consistent theoretical approach for the calculation of the Survival Probability for central dijet production . These calculations are performed in a model of high energy soft interactions based on two ingredients:(i) the results of N=4 SYM, which at the moment is the only theory that is able to deal with a large coupling constant; and (ii) the required matching with high energy QCD. Assuming, in accordance with these prerequisites, that soft Pomeron intercept is rather large and the slope of the Pomeron trajectory is equal to zero, we derive analytical formulae …
We calculate the cross section for $p p \to W^{+} W^-$ in the recently developed $k_{\rm T}$-factorisation approach, including transverse momenta of the virtual photons. We focus on processes with single and double proton dissociation. First we discuss the gap survival on the parton level as due to the emission of extra jet. Both the role of valence and sea contributions is discussed. The hadronisation of proton remnants is performed with {PYTHIA 8} string fragmentation model, assuming a simple quark-diquark model for proton. Highly excited remnant systems hadronise producing particles that ca…
Double diffractive Higgs production at $pp$ (or $\bar{p}p$) colliders continues to attract attention as a potential signal in the search for the boson. We present improved perturbative QCD estimates of the event rates for both the exclusive and inclusive double diffractive Higgs processes, paying particular attention to the survival probability of the rapidity gaps. We find that the major uncertainty is in the prediction for the survival probability associated with soft rescattering. We show that an analogous process, the double diffractive production of a pair of jets with large values of $E_…
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
提出了一种新的方法来解决双能隙排斥衍射pp散射中产生大质量系统(H =双喷流,重夸克偶素,希格斯玻色子)的快度能隙生存问题,pp -> p +(gap)+ H +(gap)+p.高质量系统是在质子之间交换两个胶子的硬散射过程中产生的。它的振幅可以用质子中的胶子广义部分子分布(GPD)来计算,GPD可以用排斥ep散射中的J/psi产生来测量。硬散射过程中修改软旁观者的相互作用,我们计算在一个独立的方式在pp弹性散射振幅。来自非弹性中间态的贡献被抑制。得到了衍射中硬相互作用和软相互作用的简单几何图象。在TeV能量的PP散射的黑盘极限的发病强烈抑制衍射在小碰撞参量,是在确定RGS概率的主要因素。硬相互作用和软相互作用之间的关联(例如,由于质子的长程π介子场的散射,或者由于部分子之间可能的短程横向关联)进一步降低了RGS概率。我们还研究了衍射截面对末态质子横动量的依赖性(“衍射图样”)。通过测量这种依赖性,人们可以对硬相互作用和软相互作用的相互作用进行详细的测试,甚至可以提取质子中胶子GPD的信息。这样的研究似乎是可行的计划在大型强子对撞机的前向探测器。
We consider photon-initiated events with large rapidity gaps in proton-proton collisions, where one or both protons may break up. We formulate a modified photon PDF that accounts for the specific experimental rapidity gap veto, and demonstrate how the soft survival probability for these gaps may be implemented consistently. Finally, we present some phenomenological results for the two-photon induced production of lepton and $W$ boson pairs.
We consider the absorptive corrections and the rapidity gap survival factor which are necessary to provide the unitarization of the BFKL Pomeron. In particular we discuss the role of the enhanced screening diagrams.
Possible evidence for color transparency from dijet production with large rapidity gaps in $γp$ scattering at HERA and how to test it in $γp, γA$ scattering
We estimate the value of the survival probability for central exclusive production, in a model, which is based on the CGC/saturation approach. Hard and soft processes are described in the same framework. At LHC energies, we obtain a small value for the survival probability. The source of the small value, is the impact parameter dependence of the hard amplitude. Our model has successfully described a large body of soft data: elastic, inelastic and diffractive cross sections,inclusive production and rapidity correlations, as well as the $t$-dependence of deep inelastic diffractive production of …
We present an estimate of survival probability from an eikonal mini- jet model implemented with a proposal for soft gluon resummation to all orders. We compare it with experimental data for diffractive di-jet production from LHC experiments, CMS and ATLAS, both at LO and NLO order.
We discuss a model for soft gluon re-summation based on a statistical description of independent emissions during inelastic collisions. The model is applied to estimate Survival Probabilities at the LHC. A comparison with other models and experimental data is presented.
We discuss photon-photon fusion mechanisms of dilepton production in proton-proton collisions with rapidity gap in the main detector and one forward proton in the forward proton detectors. This is relevant for the LHC measurements by ATLAS+AFP and CMS+PPS. Transverse momenta of the intermediate photons are taken into account and photon fluxes are expressed in terms of proton electromagnetic form factors and structure functions. Differential distributions in $ξ_{1/2}$, $M_{ll}$, $Y_{ll}$, $p_{t,ll}$, $M_R$ %pamietac wyjasnic M_R w tekscie are shown and the competition of different mechanisms is…
Recent results for the total and inelastic hadronic cross-sections from LHC experiments are compared with predictions from a single channel PDF driven eikonal mini-jet model and from an empirical model. The role of soft gluon resummation in the infrared region in taming the rise of mini-jets and their contribution to the increase of the total cross-sections at high energies are discussed. Survival probabilities at LHC, whose theoretical estimates range from circa 10 percent to a few per mille, will be estimated in this model and compared with results from QCD inspired models and from multi cha…
I present theoretical results for the top quark pair total cross section, and for the top quark transverse momentum and rapidity distributions at Tevatron and LHC energies. I also present results for single top quark production in the t- and s-channels and also via associated production with a W boson. The calculations include approximate NNLO corrections that are derived from NNLL soft-gluon resummation.
We provide a method for the all order computation of small x contributions at the leading logarithmic level to cross-sections which are differential in rapidity. The method is based on a generalization to rapidity distributions of the high energy (or k_T) factorization theorem hitherto proven for inclusive cross-sections. We apply the method to Higgs production in gluon-gluon fusion, both with finite top mass and in the infinite mass limit: in both cases, we determine all-order resummed expressions, as well as explicit expressions for the leading small x terms up to NNLO. We use our result to …
We analyze the Drell-Yan lepton pair production at forward rapidity at the Large Hadron Collider. Using the dipole framework for the computation of the cross section we find a significant suppression in comparison to the collinear factorization formula due to saturation effects in the dipole cross section. We develop a twist expansion in powers of Q_s^2/M^2 where Q_s is the saturation scale and M the invariant mass of the produced lepton pair. For the nominal LHC energy the leading twist description is sufficient down to masses of 6 GeV. Below that value the higher twist terms give a significa…
We present a new framework for the modelling of hard diffraction in pp and ppbar collisions. It starts from the the approach pioneered by Ingelman and Schlein, wherein the single diffractive cross section is factorized into a Pomeron flux and a Pomeron PDF. To this it adds a dynamically calculated rapidity gap survival factor, derived from the modelling of multiparton interactions. This factor is not relevant for diffraction in ep collisions, giving non-universality between HERA and Tevatron diffractive event rates. The model has been implemented in Pythia 8 and provides a complete description…