Higgs Potential 2022

24 Jul 2022, 08:00 → 28 Jul 2022, 18:00 Asia/Shanghai

Xiaohu SUN (Peking University)

通知2022-7-27: Don't miss the public seminar by Prof. Tao Han this evening. The zoom link is the same as below. The KouShare link is shared in this link

通知2022-7-22：Meet you in 3 days online via this Zoom link 

Zoom: 678 5324 8164
Passcode: 125125

The video records of the workshop are stored in this link, feel free watch online or download.

通知2022-6-20：根据北京市防疫要求，本次研讨会按原时间线上举办，25日-27日有会议内容安排，不收取注册费。注册截止日期相应调整到7月24日。

Higgs Potential 2022研讨会由北京大学主办，地点为北京大学物理学院，时间为2022年7月24日-28日，其中24日安排报到注册，25日-27日安排会议内容，28日离开。注册和收集报告截止到6月17日。

希格斯粒子发现后，精确测量其性质、深入理解电弱对称性破缺机制、以及寻找超出标准模型新物理是欧洲核子研究中心的大型强子对撞机LHC与未来对撞机实验的重点。LHC合作实验组将在今年夏季会议上，发布一系列最新采数的研究结果，并开始新的实验运行周期。因此，理解新的实验结果，规划未来的实验研究在此时显得尤为重要。本次会议旨在深度理解电弱对称性破缺机制，内容包含精确测量希格斯粒子性质、寻找双希格斯粒子产生、测量希格斯场自耦合以及寻找超出标准模型新物理等。会议将邀请国内外理论物理学家和实验物理学家共同探讨希格斯物理前沿动态和发展方向，并促进国内外理论实验学家在此前沿领域的合作。

After the discovery of the Higgs boson, the accurate measurements of its properties, an in-depth understanding of the electroweak symmetry breaking, and the searches for new physics beyond the standard model are the focus of the LHC and future collider experiments. The LHC experiments will release a series of research results from the latest data taking this summer and start new data taking cycles. Therefore, it is particularly important to understand the new experimental results and plan the future researches at this time. The purpose of this meeting is to deeply understand the mechanism of electroweak symmetry breaking, including accurately measuring the properties of the Higgs boson, searching for the double Higgs production, measuring the Higgs self-coupling and looking for new physics beyond the standard model. The workshop will invite physicists from both theory and experiments to discuss the frontier of the Higgs physics, and promote the collaboration of physicists from both theory and experiments in this the field.

注册费，老师1500元，博后800元，学生500元，家属500元，线上参加不收注册费

地方组委会： 曹庆宏、李强、冒亚军、孙小虎、周辰

Local Organizers: Qinghong Cao, Qiang Li, Yajun Mao, Xiaohu Sun, Chen Zhou;

学术组委会： 边立功、曹庆宏、陈明水、陈新、方亚泉、顾嘉荫、蒋赟、康召丰、李强、刘坤、刘衍文、马连良、冒亚军、Michael Ramsey-Musolf、舒菁、孙小虎、肖朦、于江浩、袁丽、张昊、张雷、周辰

Academic Commitee: Ligong Bian, Qinghong Cao, Mingshui Chen, Xin Chen, Yaquan Fang, Jiayin Gu, Yun Jiang, Zhaofeng Kang, Qiang Li, Kun Liu, Yanwen Liu, Lianliang Ma, Yajun Mao, Michael Ramsey-Musolf, Jing Shu, Xiaohu Sun, Meng Xiao, Jianghao Yu, Li Yuan, Hao Zhang, Lei Zhang, Chen Zhou;

    

                          公共报告：   

                          会议日程：   

Contact: Xiaohu.Sun@pku.edu.cn

Monday, 25 July

09:00 → 09:15 Openning

09:00 Welcome from PKU

Speaker: Prof. Yajun Mao (Peking University)

09:10 Introduction

Speaker: Prof. Xiaohu SUN (Peking University)

Slides HP2022-intro.pdf

09:15 → 20:30 Higgs & indirect BSM

Conveners: Prof. Jiayin Gu (Fudan University) , Prof. Mingshui CHEN (IHEP) , meng xiao (Zhejiang University) , 昊 ZHANG (Institute of High Energy Physics, Chinese Academy of Sciences)

09:15 Higgs precision measurements at CMS and ATLAS

Invited plenary talk

Speaker: Ulascan Sarica (U)

Slides 20220725.pdf

09:45 Measurement of the Higgs boson differential fiducial cross sections in the four-lepton decay channel in pp collisions at $\sqrt{s}$ = 13 TeV

The talk would cover the properties of the Higgs boson measured in the $\mathrm{H}\rightarrow{\rm Z}{\rm Z}\rightarrow4\ell$ ($\ell={\rm e},\mu$) decay channel. For this, a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV is used, corresponding to an integrated luminosity of $137~\mathrm{fb}^{-1}$ recorded by the CMS detector at the LHC. In the measurements, the fiducial cross section is reported with respect to several observables sensitive to the production and decay of the Higgs boson, where the results are compared with theory predictions.

Speaker: Dr Tahir Javaid (BUAA)

Slides Higgs_potential_25072022.pdf

10:05 Measurements of the Higgs boson inclusive and differential fiducial cross-sections in the diphoton decay channel with 𝒑𝒑 collisions at √s = 13 TeV with the ATLAS detector

A measurement of inclusive and differential fiducial cross-sections for the production of the Higgs boson decaying to two photons is performed using 139 fb−1 of proton–proton collision data recorded at √s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio, in a fiducial region closely matching the experimental selection, is measured to be 67 ± 6 fb, which is in agreement with the state-of-the-art Standard Model prediction of 64 ± 4 fb. In addition, the cross-section in four fiducial regions sensitive to various Higgs boson production modes and differential cross-sections as function of several observables are measured. All the measurements are found to be in agreement with the Standard Model predictions. The measured transverse momentum distribution of the Higgs boson is used as an indirect probe of the Yukawa coupling of the Higgs boson to the bottom and charm quarks. In addition, five differential cross-section measurements are used to constrain anomalous Higgs boson couplings to vector bosons in the Standard Model effective field theory framework.

Speaker: Mr Gangcheng Lu (IHEP, CAS)

Slides Higgs_Potential_2022_final.pdf

10:25 Helicity amplitudes without gauge cancellation for electroweak processes

Multiple EW vector boson amplitudes are known to have bad energy behavior for individual Feynman diagrams, which causes many problems for numerical and theoretical analysis. Based on Goldstone equivalence theorem(GET), we introduce a new representation of Feynman rules that makes GET manifest, while reproduces the exact results of the amplitudes. The new helicity has no subtle gauge cancellation, every diagram has a specific physical interpretation. We implement this new Feynman rules into numerical codes of HELAS (Helicity Amplitude Subroutines) and study several process with the new HELAS.

Speaker: Dr Junmou （俊谋） Chen （谌） (Jinan University (Guangdong))

Slides HELAS-Higgs-potential.pdf

10:45 Resolving Degenerate 125 GeV Higgs Bosons

The CP property of the 125 GeV Higgs boson remains a mystery nowadays, which implies the possibility of new physics. We consider a scenario that degenerated 125 GeV CP-even and CP-odd Higgs bosons in a CP conserving Lagrangian will contribute to nontrivial CP measurement. We use 2HDM as an example to show that DiHiggs production in future hadron and electron-positron colliders are potentially resolving such cases.

Speaker: 昌龙 许 (school of physics Peking Uniersity)

11:05 Coffee Break/茶歇 + Photo/集体照Zoom

11:25 Higgs couplings at future colliders

Invited plenary talk

Speaker: Zhen Liu (FNAL)

11:55 Highlights in CEPC

Invited plenary talk

Speaker: Prof. Yaquan FANG Yaquan (高能所)

Slides HiggsPotential2022.pdf

12:25 Probing Higgs $CP$ properties at the CEPC

In the Circular Electron Positron Collider (CEPC), a measurement of the Higgs \textit{CP} mixing through $e^{+} e^{-} \rightarrow Z H \rightarrow l^{+} l^{-}(\mu^{+} \mu^{-} / e^{+} e^{-}) H(\rightarrow b \bar{b} / c \bar{c} / g g)$ process is presented, with $5.6\ \mbox{ab}^{-1}$ $e^{+} e^{-}$ collision data at the center-of-mass energy of $240\ \mathrm{GeV}$. In this study, the \textit{CP}-violating parameter $\hat{\alpha}_{A \tilde{Z}}$ is constrained between the region of $ -6.69\times 10^{-2}$ and $6.32 \times 10^{-2}$ and $\hat{\alpha}_{Z \tilde{Z}}$ between $-1.67 \times 10^{-2}$ and $1.65 \times 10^{-2}$ at $95\%$ confidence level. This study demonstrates the great potential of probing Higgs $CP$ properties at the CEPC.

Speaker: Qiyu Sha

Slides Higgs_potential_CEPC_Higgs_CP.pdf

12:45 Lunch break/午休

14:00 Higgs precision prediction

Invited plenary talk

Speakers: Prof. Lilin Yang (Zhejiang University) , Lilin Yang (Zhejiang University)

Slides 2022-07-25_Higgs_Potential.pdf

14:30 Dihedral Angle Observable for Measuring CP Property of Top-Higgs Interaction

We propose a new dihedral angle observable to measure the CP property of the interaction of top quark and Higgs boson in the ttH production at the 14 TeV LHC. We consider two decay modes of the Higgs boson, H → bb and H → γγ, and show that the dihedral angle distribution is able to distinguish the CP-even and the CP-odd hypothesis at 95% confidence level with an integrated luminosity of ∼180 fb^−1.

Speaker: Dr Rui Zhang (IHEP)

Slides rui20220725.pdf

14:50 Measuring CP properties of Higgs boson interactions with $\tau$ leptons with the ATLAS detector

This talk will present a measurement of the charge conjugation and parity ($CP$) properties in the Higgs boson interaction with $\tau$ leptons. The Yukawa interaction is generalized with a single mixing angle parameter $\phi_{\tau}$ to describe $CP$-odd interactions between the Higgs boson and $\tau$ leptons. The study is based on a measurement of $CP$-sensitive angular observables defined by the visible decay products of $\tau$ lepton decays, performed using a data sample corresponding to 139 fb$^{-1}$ of proton–proton collisions recorded at a center-of-mass energy of $\sqrt{s}$= 13 TeV with the ATLAS detector at the Large Hadron Collider. Without assuming Standard Model hypothesis for the $H\rightarrow\tau\tau$ signal strength, the mixing angle $\phi_{\tau}$ is measured to be $9 \pm 16^{\circ}$, with an expected value of $0 \pm 28^{\circ}$ at the 68\% confidence level. The pure $CP$-odd hypothesis is disfavoured at 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model as well as $CP$-violating scenarios.

Speaker: Huanguo Li (Nanjing University)

15:10 ATLAS Higgs Combination

This talk will present the latest ATLAS Higgs combination result at the Higgs symposium to show the precision map after 10-year Higgs observation.

Speakers: Changqiao LI (SJTU & TDLI) , 昌樵 李 (Shanghai Jiao Tong University)

15:30 Higgs Combination in CMS

This talk will present the latest combined measurement of Higgs cross sections and couplings with decay channels of single Higgs, as well as the constrains of Higgs self-coupling using single Higgs events.

Speaker: fabio monti (高能所)

Slides FabioMonti_HiggsPotential_2022.pdf

15:50 Coffee Break/茶歇

16:10 Higgs rare decay at CMS and ATLAS

Invited plenary talk

Speaker: Chen Zhou (Peking University)

Slides higgspotential_chenzhou_20220725.pdf

16:40 Constraining the Higgs-charm coupling at CMS

The Higgs boson couplings to fermions and vector bosons have been well established since its discovery. Measuring the Higgs interaction with the charm quark is one of the next milestones on LHC, yet it is a challenging task due to the small branching ratio of H→cc̅ and the difficulty in charm tagging. This talk presents the latest search for a Higgs boson decaying to a cc̅ pair using the VH modes with the full Run 2 CMS dataset. Novel deep learning methods are applied to the analysis, including identification of the charm or double-charm jet and reconstruction of the jet mass. These novel techniques substantially improve the sensitivity of the search for H→cc̅ signal, leading to the most strength limit on Higgs-charm Yukawa coupling to date. It also marks the first observation of Z→cc̅ process at a hadron collider. Besides, the talk sheds light on future perspectives of Higgs-charm coupling measurements in the era of HL-LHC.

Speaker: Congqiao Li (Peking University)

Slides HiggsPotential2022_HiggsCharm_CongqiaoLi.pdf

17:00 Higgs boson decay to charmonia via $c$-quark fragmentation

We calculate the decay branching fractions of the Higgs boson to $J/\psi$ and $\eta_c$ via the charm-quark fragmentation mechanism for the color-singlet and color-octet states in the framework of non-relativistic QCD. The decay rates are governed by the charm-quark Yukawa coupling, unlike the decay $H\to J/\psi + \gamma$, which is dominated by the $\gamma^*$-$J/\psi$ mixing. We find that the decay branching fractions can be about $2 \times 10^{-5}$ for $H\to c{\bar c}+J/\psi$, and $6 \times 10^{-5}$ for $H\to c{\bar c}+\eta_c$. We comment on the perspective of searching for the Higgs boson to $J/\psi$ transition at the High-Luminosity LHC for testing the charm-quark Yukawa coupling.

Speaker: Dr Xiaoze Tan (Harbin Institute of Technology)

Slides HiggsPotential2022_H2Jpsicc.pdf

17:20 Probing light quark Yukawa couplings through angularity distributions in Higgs boson decay

We propose to utilize angularity distributions in Higgs boson decay to probe light quark Yukawa couplings at $e^+e^-$ colliders. Angularities $\tau_a$ are a class of 2-jet event shapes with variable and tunable sensitivity to the distribution of radiation in hadronic jets in the final state. Using soft-collinear effective theory (SCET), we present a prediction of angularity distributions from Higgs decaying to quark and gluon states at $e^+e^-$ colliders to ${\rm NNLL}+\mathcal{O}(\alpha_s)$ accuracy. Due to the different color structures in quark and gluon jets, the angularity distributions from $H\to q\bar{q}$ and $H\to gg$ show different behaviors and can be used to constrain the light quark Yukawa couplings. We show that the upper limit of light quark Yukawa couplings could be probed up to $15\sim 22\%$ level of the bottom quark Yukawa coupling in the Standard Model.

Speaker: Dr Bin Yan (IHEP)

Tuesday, 26 July

09:00 → 20:00 DiHiggs & BSM

Conveners: Jiang-Hao Yu (ITP, CAS) , Lianliang MA (Shandong University) , Prof. Yaquan FANG Yaquan (高能所) , Dr 召丰 康 (韩国高等研究院(KIAS))

09:00 Higgs Precision Physics at Current and Future Colliders

Invited plenary talk

Speaker: Prof. Shufang Su (University of Arizona)

Slides Precision_Higgs_Physics_Higgspotential_Su.pdf

09:30 Search for Higgs boson pair production in 𝜸𝜸𝐛𝐛 final state in 𝒑𝒑 collisions at √𝒔 = 13 TeV with the ATLAS detector

This talk will show an overview of searches for non-resonant and resonant di-Higgs boson production in the 𝑏𝑏 ̄𝛾𝛾 final state. The data set used corresponds to an integrated luminosity of 139 fb−1 of proton–proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider.

Speaker: 子航 贾 (Nanjing University)

Slides Zihang_HHyybb_0726.pdf

09:50 Searches for Higgs boson pair production in the 𝒃𝒃̅𝝉+𝝉− final state with 139 𝒇𝒃−𝟏 of pp collision data with the ATLAS detector

The Higgs boson (𝐻) was discovered at the Large Hadron Collider (LHC) in 2012, by the ATLAS and CMS collaborations. Many of its properties have been measured (mass, width, branching ratio), but the ultimate test of electroweak symmetry breaking is to reconstruct the Higgs potential, which can be determined from the Higgs boson trilinear self-coupling. This is uniquely accessible in the as-yet-unobserved Di-Higgs production, which is one of the primary physics goals for the High Luminosity LHC (HL-LHC). In this talk, I will present the results of searches for Higgs boson pair production in the 𝑏𝑏̅𝜏+𝜏− final state at ATLAS. The searches use 139 𝑓𝑏−1 of pp collision data with √𝑠 = 13 TeV recorded by the ATLAS experiment at the LHC between 2015 and 2018. The semi-leptonic and fully hadronic di-tau final states are considered. Upper limits are set on the non-resonant di-Higgs production cross-section assuming Standard Model kinematics and on the resonant di-Higgs production cross-section as a function of the resonance mass.

Speaker: 致源 李 (Peking University)

Slides Higgs_Potential_2022.pdf

10:10 Search for H-->aa-->4b exotic decays and VBF HH-->4b with CEPC and ATLAS

This talk will present the HH-->4b analysis result at ATLAS and also the exotic decays of 125GeV SM Higgs to light scalar pairs in 4b final states with future circular colliders such as CEPC.

Speaker: 王震

Slides Search_for_Higgs_exotic_decays_and_VBF_HH4b_with_CEPC_and_ATLAS_Zhen_Wang.pdf

10:30 Coffee Break/茶歇

10:50 Phase transition and GW

Invited plenary talk

Speaker: Fa Peng Huang (Sun Yat-Sen (Zhongshan) University)

Slides phase_transition_graivtational_wave_review.pdf

11:20 Investigating Higgs self-interaction through di-Higgs plus jet production

The Higgs self coupling measurement is quite essential for determining the shape of the Higgs potential and nature of the Higgs boson. We propose the di-Higgs plus jet final states at hadron colliders to increase the discovery sensitivity of the Higgs self coupling at the low invariant mass region. Our simulation indicates that the allowed region of the Higgs self coupling would be further narrowed from $[-1.5,6.7]$ from the most recent ATLAS report down to $[0.5, 1.7]$. Furthermore, we find negative Higgs self couplings would be disfavored beyond $2\sigma$ confidence level at a future 100 TeV collider with the help of this signal.

Speaker: Mr kangyu chai (Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China)

Slides Investigating_Higgs_self-interaction_through_di-Higgs_plus_jet_production.pdf

11:40 Search for the Higgs boson pair production in bbμμ Final State at hadron colliders

A search for Higgs boson pair production via gluon-gluon and vector boson fusion processes in $bb\mu\mu$ final state at hadron colliders is presented. The search uses Monte Carlo sample simulated from proton-proton collisions with an integrated luminosity of 300 fb$^{-1}$. An upper limit at 95% confidence level is set on the product of the Higgs boson pair production cross section and branching fraction into $bb\mu\mu$. The expected upper limit is 138 times the SM prediction. The expected 95% CL constraints on $\kappa_{\lambda}$ and $\kappa_{\rm{2V}}$, derived form limits on the HH production cross section, are found to be $-25.9< \kappa_{\lambda}< 31.3$ and $-6.4< \kappa_{\rm{2V}}< 8.6$, respectively.

Speaker: Botao Guo (Peking University)

Slides HiggsPotential2022_HHbbmm_BotaoGuo.pdf

12:00 Lunch break/午休

14:00 The Multi-lepton anomalies at the LHC and implications

Invited plenary talk

Speaker: Bruce Mellado (University of the Witwatersrand)

Slides HiggsPotential2022_multilepton_anomalies_260722.pdf

14:30 Search for non-resonant and resonant HH in the 4b final state with ATLAS

The discovery and properties measurements of the Higgs boson provide a deep understanding of the mechanism of electroweak symmetry breaking. However, the exact shape of the Brout, Englert and Higgs (BEH) potential remains unprobed. One of the parameters that determines its form is the Higgs boson’s trilinear self-coupling that can be constrained via Higgs-boson pair (HH) production. This talk will present the most to date ATLAS results of the searches of non-resonant and resonant HH in the 4b final state and the corresponding measurements on the Higgs self-coupling.

Speaker: 瑞 张 (U)

Slides HiggsPotential2022ZhangRui.pdf

14:50 Search for Higgs pair production in association with a vector boson with the ATLAS detector

This talk will present a search for Higgs boson pair (hh) production in association with a vector boson (W or Z) using 139/fb of the proton-proton collision data at √s = 13TeV recorded with the ATLAS detector. The search is performed in final states in which the vector boson decays leptonically (W → lν, Z → ll, νν with l = e, μ) and the Higgs bosons decay to a pair of b-quarks. It targets Vhh signals from both the Standard Model (SM) like non-resonant hh production and the resonant hh production predicted in some SM extensions. A 95% confidence-level upper limit of 183.5 (86.8) times the SM cross-section is observed (expected) for non-resonant Vhh production when assuming SM-like kinematics. Constraints on Higgs boson coupling modifiers are also set. For the resonant search, upper limits on the production cross-sections are derived for two specific models: one is the production of a vector boson along with a neutral heavy scalar resonance H that decays into hh, and the other is the production of a heavier neutral pseudoscalar resonance A that decays into a Z and H boson. Constraints in the parameter space of two-Higgs-doublet models are also derived.

Speaker: Mr Tong LI (Shandong University)

Slides TongLI_Vhh_HiggsPotential2022.pdf

15:10 Coffee Break/茶歇

15:30 Di-Higgs analyses from ATLAS and CMS

Invited plenary talk

Speaker: Dr Katharine Leney (Southern Methodist University)

Slides HH_ATLAS+CMS.pdf

16:00 HH Combination in CMS

A combined measurement of the HH cross section and Higgs self-coupling was done by CMS at the beginning of 2022, in preparation for the 10th Anniversary of the Higgs discovery. This talk will present these exciting results.

Speaker: Jin Wang (IHEP)

Slides HHCombinationCMS_JinWang_20220726.pdf

16:20 H+HH combination @ ATLAS

Constraints on the Higgs boson self-coupling are set by combining the the double-Higgs boson analyses with the single-Higgs boson analyses . The data used by these analyses were recorded by the ATLAS detector at the LHC in proton-proton collisions at s√=13 TeV and corresponds to an integrated luminosity of 126-139 \ifb.

Speakers: Kunlin RAN (Beijing) , RAN Kunlin, Yanping Huang (高能所)

Slides kunlinRan_HHHComb_20220726.pdf

Wednesday, 27 July

09:00 → 18:10 Direct BSM

Conveners: Li Yuan (Beihang University) , Dr Ligong Bian (ITP/KITPC) , Dr Xin Chen (University of Wisconsin-Madison) , Mr Yun JIANG (U.C. Davis)

09:00 Geometric and Topological Higgs Mechanisms: Mass Generations and Massive Scattering Amplitudes

Invited plenary talk

Speaker: Prof. Hong-Jian HE (Shanghai Jiao Tong University)

09:30 Dynamics of electroweak phase transitions in the singlet-extend model.

It has been demonstrated that first-order phase transitions (PTs) are achievable in a large number of BSM models. However, the successful nucleation of PT vacuum bubbles is often overlooked. Using the singlet model as an example, we will present the possible patterns of PTs achieved and build the connection to the vacuum structure at zero temperature. In this talk we focus on the one-step PTs and discuss the PT dynamics from nucleation and percolation. We find that bubble nucleation may be unsuccessful even though first-order PTs happened, and low temperature PTs favors relatively slow PTs. Finally, we comment on the limitations of studying the physics of PTs using the mean-field approach.

Speaker: Mr Haibin Chen (Sun Yat-sen University)

Slides HIggsPotential2022_singlet_PT.pdf

09:50 Primordial black holes from an electroweak phase transition

We propose a mechanism that forms primordial black holes (PBHs) via a first-order electroweak phase transition (FOEWPT). The FOEWPT is realized by extending the Standard Model with a real singlet scalar, while the PBH formation is achieved by the collapse of non-topological solitons called Fermi-balls. Such solitons form via trapping fermions in the false vacuum during the FOEWPT, and they eventually collapse into PBHs due to the internal Yukawa attractive force. We demonstrate that a scenario with PBH dark matter candidate can exist, and the typical experimental signals include FOEWPT gravitational waves and the multi-lepton/jet or displaced vertex final states at the LHC.

Speaker: Dr Ke-Pan Xie (University of Nebraska-Lincoln)

Slides Higgs_potential_online.pdf

10:10 The triplet Higgs leptogenesis

The triplet Higgs leptogenesis

Speaker: Chengcheng Han (中山大学)

10:30 Coffee Break/茶歇

10:50 W boson mass: EW Fits and New Physics

Invited plenary talk

Speaker: Dr Lei Wu (Nanjing Normal University)

11:20 Electroweak phase transition in the 2HDM: Collider and Gravitational Wave

The knowledge of the Higgs potential is crucial for understanding the origin of mass and the thermal history of our Universe. We show how collider measurements and observations of stochastic gravitational wave signals can complement each other to explore the multiform scalar potential in 2HDM. Accounting for theoretical and current experimental constraints, we analyze the key indredients in the shape of the Higgs potential triggering the transmutation in phase transition, focusing on the barrier formation and the upliftment of the true vacuum. The strong phase transition regime is favored for lower scalar masses, rendering strong extra motivation for collider searches. We contrast the dominant colllider signals at the HL-LHC with observable gravitational wave signal at LISA. We obtain that the HL-LHC will be able to cover a vast range of the strong phase transition parameter space, with scalar decays to heavy fermions being the most promising smoking gun signatures.

Speaker: 永成 吴 (N)

Slides ycwu_EWPT_2HDM_HiggsPotential2022.pdf

11:40 Gravitational wave searches of the type-II seesaw model

In this talk, we will firstly briefly review the type-II seesaw model that is responsible for non-vanishing neutrino masses and the baryon asymmetry of the Universe. Then after discussing its collider signatures, we will explain how to investigate this model using gravitational wave searches at future gravitational wave observatories such as BBO and DECIGO. Time permitting, the complementarity between collider and gravitational wave searches for this model will also be discussed. This talk is based on: https://arxiv.org/abs/2203.01561

Speaker: Yong Du (ITP CAS)

Slides HiggsPotential2022-Yong_Du.pdf

12:00 Domain wall networks from first-order phase transitions and produced gravitational waves

In the first-order phase transitions(PTs) bubble collision is an important source of gravitational waves(GW). Following this process, the domain walls can be formed when degenerate true vacua occur as a result of the breaking of a discrete symmetry. Using lattice simulations, we study the dynamical evolution of domain walls and compute the produced power spectrum of GWs. It turns out that the network of the domain wall is formed after the completion of PTs and the lifetime of the wall network largely depends on whether or not the degenerate vacua are lifted. We conclude that domain wall networks continue to produce GWs in the aftermath of PTs, leading to dramatically changing the spectral shape and enhancing the magnitude by about one order at lower wave numbers.

Speaker: Mr dongdong wei (SYSU)

Slides Domain_wall_networks_from_first-order_phase_transitions_and_produced_gravitational_waves.pptx

12:20 Lunch break/午休

14:00 Review of g-2 recent progresses

Invited plenary talk

Speaker: Prof. Liang Li (Shanghai Jiao Tong University)

14:30 利用对撞机上长寿命粒子信号检验电弱相变

We study the scenarios where a strong first order electroweak phase transition~(FOEWPT) is triggered by a light singlet scalar, which has feeble interactions to the Higgs. Since the singlet scalar is light and has weak couplings, it can decay at a macroscopic distance away from the collision point. Therefore, it can be regarded as a long-lived particles~(LLP) in such scenarios. We perform the searches of the LLPs from the exotic Higgs decays, at the FASER, MAPP and CMS-Timing detectors of the 14 TeV HL-LHC, to probe the FOEWPT. In certain scenarios, we show that the LLP searches can help to reach the parameter space of the FOEWPT remarkably, where the searches for promptly exotic Higgs decays are not valid.

Speaker: Wei Liu (Nanjing University of Science and Technology)

Slides talk-EWPT_LLP-Weiliu.pdf

14:50 Searches for FCNC interactions of the top quark with the ATLAS experiment

The large integrated luminosity collected by the ATLAS detector at the highest proton-proton collision energy provided by LHC allows to probe the presence of new physics that could enhance the rate of rare processes in the SM. The LHC can therefore gain considerable sensitivity for Flavour Changing Neutral Current (FCNC) interactions of the top quark. In the SM, FCNC involving the top-quark decay to another up-type quark and a neutral boson are so small that any measurable branching ratio for such a decay is an indication of new physics. The ATLAS experiment has performed searches for FCNC couplings of the top quark with a photon, gluon, Z boson or Higgs boson. In this contribution, the most recent results are presented, which include the complete data set of 139/fb at 13 TeV collected at the LHC during run 2 (2015-2018). The large data set, together with improvements in the analysis, yields a strong improvement of the expected sensitivity compared to previous experiments and partial analyses of the LHC data.

Speaker: mingming xia (Tsinghua University)

15:10 Search for Dark Higgs at ATLAS and potential to utilize the Xbb tagger

This talk will present the latest searches for Mono-H125 and Mono-Scalar productions with SM and BSM Higgs as a direct probe to BSM portal of new physics and especially Dark Matter. A potential of utilizing the boosted Xbb tagger will be also discussed.

Speakers: Changqiao LI (SJTU & TDLI) , Qibin Liu (TDLI & SJTU)

15:30 Coffee Break/茶歇

15:50 BSM Higgs searches at the LHC

Invited plenary talk

Speaker: Jianming Qian (University of Michigan)

Slides HBSM_PKU2022.pdf

16:20 CP Phases in 2HDM and Effective Potential: A Geometrical View

Using a geometric description of 2HDM, we classify CP invariants into three independent sectors such as scalar potential, Yukawa interaction and CKM matrix. Thermal effective potential of 2HDM is calculated in a basis invariant way. It is shown that the CP violation in Yukawa interactions can contribute to effective potential at one loop level but the CP phase in the CKM matrix cannot leak to effective potential at all orders. In the 2HDM with a softly broken Z2 symmetry, the leading thermal correction tends to restore the CP symmetry at high temperature.

Speaker: 焜 程 (北京大学物理学院)

16:40 New physics hints with 2HDM under the Higgs Boson Precision Measurements

We perform comparative studies for four types of the two Higgs Doublet Models (2HDMs) under the precision measurements of the Standard Model (SM) Higgs observables at the proposed Higgs factories. The exploration for the discovery potential is up to one-loop level. We find 5σ observability from the global fitting in a significant theory parameter space at future Higgs factories. We also examine the extent to which the different 2HDM theories may be distinguishable from one to the other at the 95% Confidence Level with four benchmark points as case studies. It confirms that the impacts of loop corrections are found to be significant in certain parameter regions.

Speaker: 伟 苏 (university of Adelaide)

17:00 A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in $pp$ collisions at $\sqrt{s}=13$~TeV with the ATLAS detector

A search for heavy Higgs bosons decaying into a pair of vector bosons and produced in association with a vector boson is performed, using final states with two leptons of the same electric charge (electrons or muons), missing transverse momentum and jets. A data sample of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of $139~\mathrm{fb^{-1}}$. The observed data are in agreement with Standard Model background expectations. The results are interpreted using higher dimensional operators in an Effective Field Theory. The upper production cross-section limits at 95% confidence level are calculated as a function of the heavy Higgs boson mass and coupling strengths to vector bosons. Limits are set in the Higgs boson mass region 300 to 1500 GeV, and depend upon the assumed couplings. The highest heavy Higgs boson mass excluded with the coupling combinations explored is 900 GeV. Limits on coupling strength are also provided.

Speaker: yue xu (Tsinghua University)

Slides GHH_20220727.pdf

17:20 Search for scalar leptoquarks in the btautau final state with the ATLAS detector

This talk will present a search for scalar leptoquarks in btautau final state using a data sample corresponding to 139 fb$^{-1}$ of proton–proton collisions recorded at a center-of-mass energy of $\sqrt{s}$= 13 TeV with the ATLAS detector at the Large Hadron Collider. The signal benchmark model considered is a scalar leptoquark with an electric charge of 4/3e and quantum numbers 3B + L = -2, which decays exclusively into a b-quark and a tau-lepton. The talk will outline the main part of the analysis, from the event selection to the background estimation and the result extraction through a fit performed on the signal regions. No significant excess above the Standard Model prediction is observed in the explored leptoquark mass range (0.4-2.5 TeV), and 95% confidence-level upper limits are set on the production cross-section times branching fraction of leptoquarks decaying to b-tau. Based on the analysis results leptoquark masses below 1.26~TeV, 1.30~TeV and 1.41~TeV are excluded for a scalar leptoquark Yukawa coupling to b-quark and tau-lepton of 1.0, 1.7 and 2.5, respectively.

Speaker: Antonio De Maria (Nanjing University)

Slides Slides_HiggsPotential_2022_LQbtautau_ADM.pdf

17:40 → 18:00 Closing

17:40 HiggsPotential2022 summary

Speaker: Prof. Xiaohu SUN (Peking University)

Slides HP2022-closing.pdf

20:00 → 22:00 Public talk at the 10th anniversary of the Higgs boson discovery

20:00 The Higgs boson: The past, present, and future

Speaker: Prof. Tao Han (Univ. of Pittsburgh &amp; TsingHua University)

Poster poster_hd.jpeg