微扰量子场论研讨会

14 May 2021, 12:00 → 16 May 2021, 18:05 Asia/Shanghai

上海新世界丽笙大酒店

HuaXing Zhu, Jun Gao, Zhao Li

量子场论是结合了经典场论，相对论，和量子力学的统一框架，是物理学的普适语言，在粒子物理和核物理，宇宙学，弦论，凝聚态物理，数学物理等众多领域中有广泛应用。研究量子场论的一个主要方法是微扰论。本次研讨会聚焦于量子场论中微扰论方法的发展和应用，讨论主题包括：

• 散射振幅
• 费曼积分的计算
• QCD和电弱辐射修正
• 规范理论的红外结构
• QCD因子化，重求和，和幂次修正
• 喷注物理
• Parton Shower和蒙特卡洛事例生成
• 微扰量子场论的其它发展和应用

会议现场收取注册费：1000元（老师或博士后），500元（学生）; 注册费已包含午餐及会议晚宴费用（家属不另收取费用），住宿费用自理

网上注册截止日期：2021年5月4日

会议及住宿地址：上海新世界丽笙大酒店，酒店住宿 600元/晚（人民广场对面，距南京西路步行街50米，外滩1.5公里）

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会议组织方：上海交通大学、浙江大学、中国科学院高能物理研究所、北京大学高能物理中心、李政道研究所

会议联系人：贺刚(hegang@sjtu.edu.cn)，高俊(jung49@sjtu.edu.cn)

Friday, 14 May

会议注册

Saturday, 15 May

07:00 早餐

08:00 注册

Session 1

1 Openning Remarks

2 Some results of one-loop reduction

Some results of one-loop reduction

Speaker: Prof. 波 冯 (浙江大学)

Slides Problem-one-loop.pdf

3 Theoretical calculations for muon g-2

TBD

Speaker: 旭 冯 (Peking University)

Slides gm2.pdf

10:00 茶歇

Session 2

4 A Long Journey to a full NLO calculation in CGC formalism

Color Glass Condensate (CGC) formalism is an effective formalism in QCD, and it allows us to compute multiple scattering and evolution in dense gluon systems. Full NLO order calculations are usually very challenging in CGC, yet they also reveal rich QCD dynamics. The simplest case, which is the single hadron production in $pA$ collisions, involves DGLAP and BK evolutions as well as the threshold resummation. Besides, the numerical calculation of the NLO corrections requires a tremendous amount of work and many fun and creative tricks. After a long journey in this NLO calculation, we finally may be able to reach a reliable and complete NLO calculation in CGC soon.

Speaker: Bowen Xiao (C)

Slides pQCD-workshop-Shanghai.pdf

5 Development of auxiliary mass flow method

TBD

Speaker: Yan-Qing Ma (Peking University)

Slides YQMa20210515.pdf

6 Angularity in DIS

TBD

Speaker: Daekyoung Kang (Fudan University)

Slides angularity_DIS_Kang.pdf

12:00 自助餐

Session 3

7 Bootstrapping a two-loop four-point form factor

We develop a new bootstrap method and compute for the first time a two-loop four-point form factor in N = 4 SYM, which belongs to the non-trivial class of two-loop 2->3 scattering amplitudes with one external leg being off-shell.

Speaker: Gang Yang (Institute of Theoretical Physics, CAS)

Slides Bootstrap_Shanghai_GangYang.pdf

8 Recent progress on calculating partonic structure of hadrons from large momentum effective theory

TBD

Speaker: Jianhui Zhang (Beijing Normal University)

Slides TDLee-JHZ.pdf

9 Large-x resummation of off-diagonal deep-inelastic parton scattering

We address the next-to-leading power (NLP) resummation of large double logarithms of 1 − x to all orders in the strong coupling, which are present even in the off-diagonal DGLAP splitting kernels. The appearance of divergent convolutions prevents the application of factorization methods known from leading power resummation. Employing d-dimensional consistency relations from requiring 1/ε pole cancellations in dimensional regularization between momentum regions, we show that the resummation of the off-diagonal parton-scattering channels at the leading logarithmic order can be bootstrapped from the recently conjectured exponentiation of NLP soft-quark Sudakov logarithms. In particular, we derive a result for the DGLAP kernel in terms of the series of Bernoulli numbers found previously by Vogt directly from algebraic all-order expressions. We identify the off-diagonal DGLAP splitting functions and soft-quark Sudakov logarithms as inherent two-scale quantities in the large-x limit. We use a refactorization of these scales and renormalization group methods inspired by soft-collinear effective theory to derive the conjectured soft-quark Sudakov exponentiation formula.

Speaker: Jian Wang (Shandong University)

Slides talk_by_JWang.pdf

15:00 茶歇

Session 4

10 QCD aspects of heavy quark decays

QCD aspects of exclusive heavy-hadron decays will be discussed with an emphasis on the perturbative factorization properties for the resulting hadronic matrix elements in the heavy quark expansion and on the systematic discussions of the distinct dynamical mechanisms governing the flavor-changing form factors beyond the leading-power approximation. Phenomenological implications of the technical improvements for evaluating the heavy hadron decay amplitudes will be further elaborated with a number of interesting exclusive processes accessible at the LHCb and Belle II experiments.

Speaker: Prof. Yu-Ming Wang (Nankai University)

Slides Heavy+quark+decays+in+QCD.pdf

11 PDFs with lattice input

TBD

Speaker: Tie-Jiun Hou (Northeastern University)

Slides 2021.0515_CT18CSa.pdf

16:30 休息

Session 5

12 Efficient computation of NLO corrections for HH production and ZH production via gluon fusion

Higgs boson pair(HH) production and Z boson and Higgs boson(ZH) associated production are both very important processes at the LHC. Their gluon fusion channel is a class of loop-induced process, whose NLO correction in QCD is quite challenging, due to the appearance of difficult two loop Feynman integrals. In this talk, I will show our progress of the NLO calculations of these two processes. Recently, we present a precise and efficient computation of the two-loop amplitudes entering HH and ZH production processes via gluon fusion. Our approach is based on the small-external-mass expansion while keeping the full dependence on the top quark mass and other kinematic invariants. We find that our method provides precision numeric predictions in the entire phase space, while at the same time is highly efficient as the computation can be easily performed on a normal desktop or laptop computer. Our method is valuable for practical phenomenological studies. Finally, I will show some preliminary phenomenological results for NLO ZH production via gluon fusion, which are unknown for us before.

Speaker: Dr 国兴 王 (Zhejiang University)

Slides HH_HZ_Guoxing_Wang1.pdf

13 New structure for Feynman integrals in N=4 SYM

TBD

Speaker: Zhenjie Li (Institute of Theoretical Physics, CAS)

Slides dp_wl.pdf

14 Three-loop color-kinematics duality and Higgs amplitudes

We compute full-color three-loop form factors by using color-kinematics duality and unitarity cut methods. These form factors may be understood as the $\mathcal{N}=4$ SYM counterparts of Higgs plus three-gluon amplitudes and are also expected to provide the maximally transcendental part of the latter.

Speakers: Siyuan Zhang (University of Chinese Academy of Sciences) , 冠达 林 (Peking University)

Slides SiyuanZhang_Three-loop_color-kinematics_duality_and_Higgs_amplitudes_(part_1)(2).pdf

15 Three-loop color-kinematics duality and Higgs amplitudes

We compute full-color three-loop form factors by using color-kinematics duality and unitarity cut methods. These form factors may be understood as the N=4 SYM counterparts of Higgs plus three-gluon amplitudes and are also expected to provide the maximally transcendental part of the latter.

Speaker: 冠达 林 (Peking University)

Slides GuandaLin-Three-loop-color-kinematics-duality-and-Higgs-amplitudes-2.pdf

16 A new method for amplitude with multi fermion line

A new method for amplitude with multi fermion line is given. The new method is mainly focusing on simplifying the fermion line calculation, including the simplification of the spinor, Dirac matrices product and others. The comparison with other programs is given and the results show that the new method surely greatly improves the calculation speed and one can expect that the more final states, the better improvement.

Speaker: Mr Feng Zhang (IHEP)

Slides zhangfeng_amplitude_with_multi_fermion_line_.pdf

17 Exploring jet substructure with the celestial conformal symmetry

TBD

Speaker: Mr Hao Chen (ZJU)

Slides HaoChen.pdf

18 Compton Scattering Total Cross Section at NLO

TBD

Speaker: Xiaoyuan Zhang (H)

Slides Compton_Xiaoyuan.pdf

19:00 晚宴

Sunday, 16 May

07:00 早餐

Session 6

19 Two-loop Feynman integrals with masses

TBD

Speaker: Prof. Lilin Yang (Zhejiang University)

Slides LLYang.pdf

20 Scattering amplitudes, Feynman integrals, and Wilson loops

I will briefly review recent progress in computing multi-loop scattering amplitudes in planar N=4 super-Yang-Mills by exploiting the duality to Wilson loops, and how the method can be used to compute a wide range uniform-transcendental Feynman integrals.

Speaker: Prof. Song He (ITP-CAS)

Slides WL2.pdf

21 CGC forward hadron production

In this talk, I will present the higher order predictions for forward hadron production within the color glass condensate (CGC) framework. I will also show preliminary results for forward jet productions in the small-x limit.

Speaker: Xiaohui Liu (Beijing Normal University)

Slides sjtu-latest.pdf

10:15 茶歇

Session 7

22 Progress in FDC Project

TBD

Speaker: Prof. Jianxiong jxwang@ihep.ac.cn (高能所)

Slides jxwang-2021.5.16.pdf

23 The Time-reversal Odd Side of a Jet

We re-examine the jet probes of the nucleon spin and flavor structures. We find for the first time the time-reversal odd (T-odd) component of a jet, conventionally thought to vanish, can survive due to the non-perturbative fragmentation and hadronization effects. This additional contribution of a jet will lead to novel jet phenomena relevant for unlocking the access to several spin structures of the nucleon, which were thought to be impossible by using jets. As examples, we show how the T-odd constituent can couple to the proton transversity at the Electron Ion Collider (EIC) and can give rise to the anisotropy in the jet production in $e^+e^-$ annihilations. We expect the T-odd contribution of the jet will have broad applications in high energy nuclear physics.

Speaker: Hongxi Xing (South China Normal University)

Slides pqcd_shanghai_xing.pdf

24 Calculation of master integrals for single top quark hadron production

none.

Speaker: Long-Bin Chen (GuangZhou University)

Slides st-mi-chen.pdf

12:15 自助餐

Session 8

25 Parton Distribution Functions matching in LaMET

In this talk, I will report the matching of parton distribution functions (PDFs) in Large Momentum Effective Theory (LaMET). First I will report the matching of gluon and quark PDFs in regularization independent momentum subtractioin (RI/MOM) scheme. Then I will report the next-to-next-to-leading order (NNLO) corrections to the nonsinglet quark quasi distribution functions.

Speaker: Dr Ruilin Zhu (Nanjing Normal University)

Slides LaMETMatch-Shanghai-RLZ1.pdf

26 The classification of high dimensional gluon operators

The contribution of high dimensional operators in effective field theory becomes important as the experimental precision increases in LHC and future colliders. However, it can be very difficult to generate and classify these operators since the number of operators increases very fast as dimension increases. We propose a systematical method to generate and classify pure gluon operators with a given length to arbitrary high dimensions. A diagramatic representation of gluon operators is proposed to manifest their symmetries and relations. The infinite set of high dimensional operators are generated from a finite set of "primitive operators" by adding pairs of covariant derivatives. The possible redundancy among the operators are removed with the help of Groebner basis. The representations of permutation groups are used to dress the color factors. We explicity constructed primitive operators and Groebner basis for length-2,3,4,5 operators in D-dimensions.

Speaker: Qingjun Jin (g)

Slides gluon_operators.pdf

27 NLO EW corrections to ee->Zh/H in THDM

TBD

Speaker: Dr Bin GONG (高能所)

Slides gongb.pdf

15:30 茶歇

Session 9

28 Double logarithmic corrections at subleading power

Will discuss the double logarithimic corrections induced through the exchange of soft massive quarks at subleading power. Besides the known results, some finished but not published results will also be presented.

Speaker: Dr Tao Liu (IHEP)

Slides 1.TL.pdf

29 Recent applications of PMC

TBD

Speaker: Dr Shengquan Wang (GZU)

Slides 2.Recent_applications_of_PMC.pdf

30 喷注过程方位角关联的精确计算

The azimuthal decorrelation in vector boson+jet production due to soft and collinear QCD effects can be calculated to high precision by using recoil-free jet axes, such as the Winner-Takes-All (WTA) axis, alongside Soft-Collinear Effective Theory (SCET) methods. We present theoretical predictions at next-to-next-to-leading logarithmic accuracy for the azimuthal decorrelation and demonstrate that this result is robust when using charged tracks instead of calorimetry, and in the presence of large backgrounds, due to the features of the WTA axis. We further find contributions to the process from linearly-polarised gluon transverse momentum distributions (arising from spin superposition effects of a single incoming or outgoing parton), in both the initial and final state.

Speaker: Prof. Dingyu Shao (Fudan University)

Slides Shanghai-pQFT.pdf