Multijet events in the k_T-factorisation scheme
Stefan Höche, Frank Krauss, Thomas Teubner
提出了一种计算高能极限下多部分子产生的马尔可夫蒙特卡罗算法，并讨论了与非积分部分子密度的匹配问题。
A Markovian Monte Carlo algorithm for multi-parton production in the high-energy limit is proposed and the matching with unintegrated parton densities is discussed.
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Unweighting multijet event generation using factorisation-aware neural networks
本文提出将因子化感知神经网络矩阵元代理与无偏去加权算法结合，用于LHC多喷注事件生成，在Sherpa中实现16至350倍的计算加速。
A New Framework for Multijet Predictions and its application to Higgs Boson production at the LHC
我们提出了一个新的框架计算多喷流可观测量通过remation。该框架是基于散射振幅在渐近极限的因式分解。通过施加简单的限制的分析行为的结果时，应用远离这个限制，我们得到很好的协议与已知的最低阶微扰行为的散射振幅，和预测的行为的所有订单的微扰系列。作为应用的一个例子，我们研究的预测希格斯玻色子生产通过胶子融合在LHC与至少两个喷流。
Multijet events and parton showers
我们提出了一个通用的方法来描述多喷注事件的框架下的QCD事件发生器。我们引入了一种新的算法来匹配部分子簇射和任意矩阵元素，以通过强相互作用或电弱相互作用产生任意数量的喷流。我们开发了一个新的部分子级联代码能够处理多射流事件在LEP能源和超越。
The Analysis of Multijet Events Produced at High Energy Hadron Colliders
我们定义并讨论了一组（4 N- 4）参数，可用于分析事件中，N喷注已产生的高能强子-强子碰撞。这些多射流变量是多射流质量和（4 N- 5）独立的无量纲参数。为了说明使用的变量QCD预测的事件产生的Tevatron质子-反质子对撞机在费米实验室多达五个喷流。这些QCD的预测进行了比较，在一个模型中，多喷流事件均匀填充的N-体相空间的预测。
Heavy Quark Production at $e^+ e^-$ Colliders in Multijet Events and a New Method of Computing Helicity Amplitudes
在树水平上研究了$e^+e^-$对撞机多喷注事件中的重夸克产生。给出了总的产生率，并与无质量夸克的相应结果进行了比较。简要介绍了一种计算螺旋度振幅的新方法。1994年3月19日至26日在法国梅里贝尔举行的第29届Moriond QCD和高能强子相互作用会议上发表的讲话。
Accelerating multijet-merged event generation with neural network matrix element surrogates
利用神经网络代理加速多喷注合并事件生成，显著减少事件生成时间。
We introduce three alternative angular variables-denoted by $\tildeω_\text{min}$, $\hatω_\text{min}$, and $χ_\text{min}$-for QCD multijet event suppression in supersymmetry searches in events with large missing transverse momentum in proton-proton collisions at the LHC at CERN. In searches in all-hadronic final states in the CMS and ATLAS experiments, the angle $Δφ_i$, the azimuthal angle between a jet and the missing transverse momentum, is widely used to reduce QCD multijet background events with large missing transverse momentum, which is primarily caused by a jet momentum mismeasurement or…
Parton showers and multijet events
研制了一个用于模拟电子正电子湮没的Monte-Carlo事件发生器。特别是一种新的矩阵元和部分子簇射相结合的方法，保证了强子化参数与CMS能量的独立性。这使得第一次多射流拓扑结构的描述，例如四个射流角度，在很宽的能量范围内，而不改变模型的任何参数。我们的模拟器涵盖了标准模型的所有过程，能够描述当前和未来加速器的实验，即LEP对撞机和可能的下一代直线对撞机（NLC）。
Higher-dimensional multi-gluon interactions affect essentially all effective Lagrangian analyses at the LHC. We show that, contrary to common lore, such operators are best constrained in multi-jet production. Our limit on the corresponding new physics scale in the multi-TeV range exceeds the typical reach of global dimension-6 Higgs and top analyses. This implies that the pure Yang-Mills operator can safely be neglected in almost all specific higher-dimensional analyses at Run II.
Multijet Structure of High E_T Hadronic Collisions
CDF合作组在费米实验室Tevatron上研究了大横向能量（和E_T > 420 GeV）和大多射流不变质量（M_jets > 600 GeV）的多射流事件。所观察到的喷流多重性分布可以理解在QCD启发的指数模型，在相空间的区域，需要超越固定阶微扰理论。
At the Large Hadron Collider (LHC), the most abundant processes which take place in proton-proton collisions are the generation of multijet events. These final states rely heavily on phenomenological models and perturbative corrections which are not fully understood, and yet for many physics searches at the LHC, multijet processes are an important background to deal with. It is therefore imperative that the modelling of multijet processes is better understood and improved. For this reason, a study has been done with several state-of-the-art Monte Carlo event generators, and their predictions a…
We present results of the simulation of electroweak Higgs boson production at the Large Hadron Collider using both the NLO multijet merging and NLO matching frameworks provided by the general purpose event generator Herwig 7. For the simulation of the hard scattering processes, we use the HJets library for the full calculation and VBFNLO for the approximate calculation to compute the $2\to h+n$ amplitudes at tree-level with $n=2,3,4$ and at one-loop with $n=2,3$.
Order statistics for multijet events
本研究利用排名有序的喷流快速性分布，揭示了高能QCD动力学在LHC上的不同模拟方法之间的差异。
Resonance-aware electroweak Sudakov reweighting for multijet-merged predictions
本文提出共振感知的电弱Sudakov重加权方法，用于多喷注合并模拟，考虑自旋关联并移除光子对数，在Z+喷注和W+W−产生中验证其高能抑制效应，提供实用的虚弱Sudakov近似。
Multijet event shape variables for Mueller Navelet jet topologies
本文提出一组新的多喷注事件形状变量以研究Mueller-Navelet喷注拓扑，并通过BFKLex与NLO+PS的蒙特卡洛对比分析，验证了BFKL方法在LHC能量下描述强相互作用前渐近极限行为的可靠性。
Precision measurement of the cross section for single top production is an important test of the Standard Model (SM). The purity of the collected data in single top events is limited by the understanding of the shape and yield of background contributions. Besides electroweak and $\rm{t\bar{t}}$ processes, QCD multijet events constitute a non-negligible background for the considered signal bq$'\rightarrow$ tq ($\textit{t}$-channel) process. The data-driven technique for constraining QCD contribution, employed in the measurement of the $\textit{t}$-channel single top-quark cross section using th…
We study resonant pair production of heavy particles in fully hadronic final states by means of jet substructure techniques. We propose a new resonance tagging strategy that smoothly interpolates between the highly boosted and fully resolved regimes, leading to uniform signal efficiencies and background rejection rates across a broad range of masses. Our method makes it possible to efficiently replace independent experimental searches, based on different final state topologies, with a single common analysis. As a case study, we apply our technique to pair production of Higgs bosons decaying in…
A novel method is proposed here to precisely model the multi-dimensional features of QCD multi-jet events in hadron collisions. The method relies on the schematization of high-pT QCD processes as 2->2 reactions made complex by sub-leading effects. The construction of libraries of hemispheres from experimental data and the definition of a suitable nearest-neighbor-based association map allow for the generation of artificial events that reproduce with surprising accuracy the kinematics of the QCD component of original data, while remaining insensitive to small signal contaminations. The method i…
Multijet matrix elements and shower evolution in hadronic collisions: W b bbar + n jets as a case study
本文研究了W规范玻色子、重夸克对和n个额外喷注（n ≤ 4）的强子碰撞末态的产生。完整的部分子树级QCD矩阵元素的评估使用的ALPHA算法，并在部分子水平产生的事件，然后通过QCD簇射演化，并最终强子化使用的相干簇射演化由HERWIG蒙特卡罗提供。我们讨论了我们的Monte Carlo实现的细节，并提出了Tevatron对撞机和大型强子对撞机的现象学兴趣的结果。我们还评论的影响，我们的计算上的背景W（H -> b bbar）的生产，当只有一个b喷注标记。
Valence quarks and $k_T$ factorisation
我们在$k_T$分解框架中研究了LHC能量下的喷流产生。特别是，我们感兴趣的价夸克和胶子发起的射流。给出了相应硬矩阵元的计算方法。用蒙特卡罗事件发生器CASCADE求解了一个类似CCFM的价夸克分布演化方程，计算了价夸克和胶子引发过程的截面。
Multijet topology in high-energy nuclear collisions: jet broadening
首次从理论上研究了高能核碰撞中喷注淬火对多喷注末态喷注展宽的介质修正，发现PbPb碰撞中小喷注展宽区域增强、大区域受抑制，并揭示了喷注数量减少与重构贡献交织导致的核修正新行为。
Inferring flavor mixtures in multijet events
本文提出灵活的贝叶斯混合模型，联合推断多喷注事件的味组分与 $b$ 标记分数分布，无需参数假设，并在 $bbbb$ 信号玩具研究中验证可由数百事件恢复真实混合比例。
Too good to go: Upcycling Phase-Space Points for Multijet Processes
该研究针对多喷注过程相空间采样成本高的问题，提出循环利用相空间点的训练策略，可降低采样器适配成本，提升性能，适用于多种采样器，在LHC相关过程中验证有效。
We study 3-jet event topologies in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 13 {\rm\ TeV}$ in a configuration, where one jet is present in the central pseudorapidity region ($|η| < 2.0$) while two other jets are in a more forward (same hemisphere) area ($|η| > 2.0$). We compare various parton level predictions using: collinear factorisation, $\KT{}$-factorisation with fully off-shell matrix elements and the hybrid framework. We study the influence of different parton distribution functions, initial state radiation, final state radiation, and hadronisation. We focus on…
Quantum-annealing-inspired algorithms for multijet clustering
本研究将高能对撞机中的喷注重建表述为QUBO问题，提出受量子退火启发的算法（如弹道模拟分岔）解决多喷注聚类难题，实现了一次性全局重建超越双喷注的多喷注，突破了传统迭代方法的局限。
While the presence of a light stop is increasingly disfavored by the experimental limits set on R-parity conserving scenarios, the naturalness of supersymmetry could still be safely concealed in the more challenging final states predicted by the existence of non-null R-parity violating couplings. Although R-parity violating signatures are extensively looked for at the Large Hadron Collider, these searches always assume 100\% branching ratios for the direct decays of supersymmetric particles into Standard Model ones. In this paper we scrutinize the implications of relaxing this assumption by fo…
Many studies of possible new physics employ effective field theory (EFT), whereby corrections to the Standard Model take the form of higher-dimensional operators, suppressed by a large energy scale. Fits of such a theory to data typically use parton level observables, which limits the datasets one can use. In order to theoretically model search channels involving many additional jets, it is important to include tree-level matrix elements matched to a parton shower algorithm, and a suitable matching procedure to remove the double counting of additional radiation. There are then two potential pr…
APACIC++, A Parton Cascade in C++
本文介绍了新研制的适用于描述高能电子正电子湮没中多喷注事件的Monte-Carlo事件发生器{ \tt APACIC++}。一个新的ananterior匹配相应的矩阵元素的生产射流通过强和电弱相互作用，随后的部分子簇射模拟内部射流演化进行了详细讨论。用{ \tt APACIC++}得到的结果与其他QCD事件发生器和一些有代表性的实验数据进行了比较。
Multi-jet production in lepton-proton scattering at next-to-leading order accuracy
我总结的理论和实验状态的多射流生产在DIS。我提出了最先进的理论预测和比较，通过分析在HERA的H1和ZEUS合作收集的数据所获得的相应的实验结果。我还显示了新的预测三喷事件形状分布在NLO精度。
Possible Excess in Charged Current Events with High-Q^2 at HERA from Stop and Sbottom Production
我们研究了HERA的一个产生过程$e^+p \to \st X \to \sb W^+ X$，在R-宇称破缺超对称标准模型的框架下考虑了sbottom的一个衰变模式$\sb \to \barν_e d$.停止产生$e^+ d \to \st$和底部衰变$\sb \to \barν_e d$的过程都起源于R宇称破缺超势$λ'_{131} \hat{L}_1 \hat{Q}_3 \hat{D^c}_1$。该过程的特征之一应该是与$W$的强子衰变相对应的一个大的横向动量缺失和多喷注事件。结果表明，该信号可能出现作为一个事件过剩的充电电流（CC）过程$e^+p \to νX$与高$Q^2$在HERA。我们将预期事件分布与HERA的H1和ZEUS组最近报告的CC数据进行比较。从标准CC过程中提取信号的方法也进行了讨论。
On parton distributions beyond the leading order
适当考虑的重要性，部分子分布函数的因式分解方案的依赖性进行了强调。一个严重的错误，在通常的处理这一主题指出和正确的程序转换部分子分布函数从一个因式分解计划到另一个召回。结果表明，传统的$\overline{\rm {MS}}$和DIS定义是不好定义的，由于缺乏区分的因式分解方案依赖的部分子分布函数和重正化方案依赖的强耦合常数$α_s$。提出了一种新的部分子分布函数的定义，并简述了它在构造一致的次主导阶事件发生器中的作用。
Hard Diffraction in Sherpa
本文在SHERPA中实现了QCD次领头阶下衍射喷注产生与部分子簇射匹配的完整模拟框架，利用HERA数据验证，并论证光生过程中直接分量需被抑制，为EIC提供预测。
Event generation with Sherpa 3
本文介绍通用蒙特卡洛事件生成器Sherpa 3系列的新进展，涵盖物理模拟精度提升、模型优化及生成效率改进等多方面升级，助力高能对撞机粒子碰撞模拟研究。
We present calculations of single inclusive jet transverse momentum and energy spectra at forward rapidity ($5.2\!<\!y\!<\!6.6$) in proton-lead collisions with $\sqrt{s_{NN}}$ = 5.02 TeV. The predictions are obtained with the KaTie Monte Carlo event generator, which allows to calculate interactions within the High Energy Factorisation framework. The tree-level matrix element results are subsequently interfaced with the CASCADE Monte Carlo event generator to account for hadronisation. The effects of the saturation of the gluon density, leading to suppression of the cross section, are investigat…
Processes involving heavy quarks in associated production, are usually described in two factorisation schemes: one in which the heavy quark is treated as an infinitely massive object, decoupled from QCD evolution, and one in which it is treated on the same footing of a light quark. These two approaches only differ by the inclusion of mass suppressed terms or in the resummation of a certain class of logarithms. In view of recent results, in this talk, we present recent developments that extend a phenomenological scheme, that tries to incorporate the best of both worlds, to \NLO in Monte Carlo e…
Measurements of jet production in the photoproduction region at HERA are presented, which are sensitive to the underlying event structure. It is argued that in the photoproduction region a significant amount of multi-parton interactions in the collinear factorisation ansatz are needed to describe the measurement. A different approach for higher order parton radiation (CCFM parton showers) can also describe the measurement.
Effect of event classifiers on jet quenching-like signatures in high-multiplicity $p+p$ collisions at $\sqrt{s} = 13$ TeV
本文提出使用新事件分类器flattenicity替代V0探测器，以更准确量化高多重数p+p碰撞中的类喷注淬灭效应，PYTHIA8模拟显示其$\mathcal{P}_{\rm CP}$呈现类重离子行为。
Higgs Boson Production in Association with Multiple Hard Jets
我们阐明了一种新的技术，估计生产的多个（至少两个）硬喷流希格斯生产通过胶子-胶子融合。该方法是基于高能量因式分解，与扩展的适用范围的散射振幅源于已知的所有阶结果的分析行为的约束。该方法近似真实和虚拟的修正，并允许在一个n-部分子包容性事件样本中的条款占主导地位的高能量极限的recrimation。得到的近似匹配到已知的树级矩阵元素的生产与2和3个喷气机的希格斯玻色子，并在蒙特卡洛发生器中实现。示例结果和特征辐射模式进行了讨论。
Azimuthal correlations in Z+jet production at large transverse momenta are computed by matching Parton - Branching (PB) TMD parton distributions and showers with NLO calculations via MCatNLO. The predictions are compared with those for dijet production in the same kinematic range. The azimuthal correlations $Δϕ$ between the Z boson and the leading jet are steeper compared to those in dijet production at transverse momenta ${\cal O}(100)$ GeV, while they become similar for very high transverse momenta ${\cal O}(1000)$ GeV. The different patterns of Z+jet and dijet azimuthal correlations can be …
Dijet production as a centrality trigger for p-p collisions at CERN LHC
我们表明，在小的rapidities硬dijet生产的触发器允许建立一个定量的区别在Tevatron和LHC能量的pbar-p和p-p碰撞中心和外围碰撞。与最小偏置事件相比，这种触发强烈地降低了有效碰撞参量。这是因为质子中硬部分子（x >~ 10^{-2}）的横向空间分布比软部分子窄得多，软部分子的碰撞占总截面的主导地位。在触发器选择的中心碰撞中，大多数x >~ 10^{-2}的部分子与强度随能量迅速增加的胶子场相互作用。在LHC（在某种程度上已经在Tevatron）能量下，这种相互作用的强度接近幺正性（“黑体”）极限。这导致特定的修改的最终状态，如更高的概率多射流事件在小rapidities，强烈增加的横向动量和耗尽的纵向动量在大rapidities，和外观的长程相关性之间的快速向前/向后的碎片区域。对于产生新的重粒子（希格斯粒子，超对称粒子）的事件，预计也会有同样的模式。利用CMS-TOTEM探测器装置对这些现象进行研究是可行的，并将对QCD中强胶子场物理的探索以及LHC中寻找新粒子产生相当大的影响。
What Do Event Generators Compute? Flux Functionals from Detector Operators
该研究从探测器算符构造事例发生器的强子通量概率分布，得到红外共线安全的部分子簇射源泛函，可评估部分子簇射精度，为非QCD理论的事例生成研究提供新途径。
We present persistently amassing evidence that the CMS and ATLAS Collaborations may indeed be already registering supersymmetry events at the Large Hadron Collider (LHC). Our analysis is performed in the context of a highly phenomenologically favorable model named No-Scale F-SU(5), which represents the unification of the F-lipped SU(5) Grand Unified Theory (GUT), two pairs of hypothetical TeV-scale vector-like supersymmetric multiplets derived out of F-Theory, and the dynamically established boundary conditions of No-Scale supergravity. We document highly suggestive correlations between the fi…
Automated event generation for S-wave quarkonium and leptonium production in NRQCD and NRQED
该研究通过扩展MadGraph5_aMC@NLO框架，实现了非相对论QCD和QED中S波夸克onium和轻子onium产生过程的自动化事件生成，强调了次主导贡献对理论研究的影响。
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