Opening

• Jason Evans (SJTU/TDLI)

Some lessons from recent experimental anomalies

• JiJi Fan

Recently there have been two interesting and intriguing experimental results, one on the muon g-2 from Fermilab and one on the W boson mass from CDF. I will discuss some possible implications of these results for new physics, provided that they survive. For muon g-2, I will discuss a relatively new explanation using the loop effects of a heavy axion coupling to leptons and photons. I will provide an updated analysis of the necessary couplings, including two-loop contributions, and show that the new physics operators point to an axion decay constant on the order of 10s of GeV. I will also discuss the challenges to UV complete this explanation. For the W mass, I will discuss the implications using a set of six-dimensional operators in the SM effective field theory and comment on other further indirect tests of the physical origin for this anomalous discrepancy such as the Higgs couplings.

Recent progress in Muon g-2

• Kim Siang Khaw

Muon magnetic anomaly is a very sensitive probe to new physics beyond the Standard Model. It can be calculated with very high precision in the Standard Model and can be precisely measured using the magnetic storage ring approach. The first result from the Fermilab Muon g-2 experiment has triggered a worldwide effort in scrutinizing both the Standard Model predictions and experimental measurements of the muon magnetic anomaly. Moreover, a lot of BSM models were proposed to explain the apparent discrepancy. In this workshop, I will give a brief overview of the current status of the theoretical predictions, together with the progress of the Muon g-2 experiments at Fermilab and J-PARC.

Supersymmetry is the Physics of this Century

• Tsutomu Yanagida

SMEFT at future lepton colliders

• Jiayin Gu

B anomaly hunting at the LHC: tau b + missing search for leptoquarks

• Teppei Kitahara

One of the long-standing B anomalies is the $b \to c \tau \nu$ anomaly, which remains at $\sim 4$ sigma level. This anomaly will be confirmed or disappeared by the ongoing Belle II and LHCb experiments. In this talk, we will discuss the possibility that another crosscheck could be possible by the LHC search. In our work arXiv:2111.04748, we study non-resonant searched for new physics at the LHC by considering final states with an energetic and hadronically decaying $\tau$ lepton, a $b$-jet and large missing transverse momentum ($pp \to \tau \b + E_T^{miss}$). This channel is related to the $b \to c \tau \nu$ process by the crossing symmetry of the amplitudes. We analyze them not only within the dimension-six EFT but also in explicit leptoquark models. Although the leptoquark models provide a weaker sensitivity than the EFT, it is found that the non-resonant search of $pp \to \tau \b + E_T^{miss}$ can improve the sensitivity by $\sim 40\%$ versus a conventional $pp \to \tau + E_T^{miss}$ search in the whole leptoquark mass region. Consequently, it is expected that most of the parameter regions suggested by the B anomaly can be probed at the HL-LHC. Also, it is shown that SU(2) doublet leptoquark scenario is accessible entirely once the LHC Run 2 data are analyzed. In addition, we discuss the angular correlations among $b, \tau$ and the missing transverse momentum to discriminate the LQ scenarios.

Muon g-2 and B anomalies from Dark Matter

• Lorenzo Calibbi

We systematically build and discuss a class of models with minimal field content that can simultaneously provide: (i) a thermal Dark Matter (DM) candidate; (ii) large loop contributions to $b\to s\ell\ell$ processes able to address $R_K$ and the other $B$ anomalies; (iii) a natural solution to the muon $g-2$ discrepancy through chirally-enhanced contributions. We show what are the minimal ingredients and properties necessary to explain both anomalies through loop effects directly involving the DM particles and few other new fields. The general characteristic of this class of models is that the DM phenomenology is controlled by the same parameters that enter the flavour observables. As a consequence, they feature a high degree of correlation among DM, flavour and collider searches and thus an enhanced testability. The new particles are generally heavy enough to evade limits set by LHC searches, but could be in the reach of present and future colliders and direct detection experiments.

Recent updates on Higgs properties measurement at CMS and ATLAS

• Kun Liu (TDLI / SJTU)

After 10 years of the Higgs boson discovery, the leading Higgs production and decay channels have been observed at the Large Hadron Collider, i.e: ggF, VBF, WH, ZH, ttH and H→bb, WW, 𝛕𝛕, ZZ, 𝛄𝛄 etc. The measurement of Higgs couplings with vector bosons and with third generation of fermions has reached to 10%-15% level of precision. Moreover, Higgs self-coupling as well as Higgs couplings with muon-lepton and charm-quark are also constrained. All those measurements are in agreement with SM predictions, which plays strict constraints to new physics at the Electroweak scale. In this talk, latest updates of the Higgs properties measurements and prospectives at the LHC will be presented.

Probing electroweak phase transition with multi-TeV muon colliders and gravitational waves

• Kepan Xie

We study the complementarity of the proposed multi-TeV muon colliders and the near-future gravitational wave (GW) detectors to the first order electroweak phase transition (FOEWPT), taking the real scalar extended Standard Model as the representative model. A detailed collider simulation shows the FOEWPT parameter space can be greatly probed via the vector boson fusion production of the singlet, and its subsequent decay to the di-Higgs or di-boson channels. Especially, almost all the parameter space yielding detectable GW signals can be probed by the muon colliders. Therefore, if we could detect stochastic GWs in the future, a muon collider could provide a hopeful crosscheck to identify their origin. On the other hand, there is considerable parameter space that escapes GW detections but is within the reach of the muon colliders. The precision measurements of Higgs couplings could also probe the FOEWPT parameter space efficiently.

Higgs rare and exotic decays at CMS and ATLAS

• Chen Zhou

This talk will discuss the recent results about the rare and exotic decays of the Higgs boson from the CMS and ATLAS experiments. These decay modes are important portals to refine our understanding of the electroweak sector and search for new physics.

MeV new physics light from muon g-2

• Xiaoping Wang

The muon g-2 is an interesting observable, since it can be measured with great precision and can be computed with excellent accuracy within the Standard Model (SM). The current experimental measurement of muon g-2 shows a deviation to the SM prediction, which may be a hint of new physics. A light particle, scalar or vector, can be nature new physics candidates to explain the current muon g-2 result. If it is a light scalar with a mass around 1 MeV. It can be connected to the origin of neutrino masses and simultaneously survive current bounds on relativistic degrees of freedom in the early universe. If it is a light scalar with mass around pion mass and a coupling to muons of the order of the Standard Model Higgs coupling, it can be tested in the KOTO experiment. If it is a complex scalar with real part around 200 MeV, it can explain muon g-2 and can be tested via electron g-2 experiment. If the light particle for muon g-2 is a dark photon and its mass is time-varying due to environmental effects, for mass around tens of MeV, the muon g–2 solution from the kinetic mixing dark photon becomes viable again. The scenario can be further tested by reanalyzing the existing data with timing information included.

First Results from XENONnT

• Fei Gao

CP/flavor-safe SUSY model for light sleptons

• Norimi Yokozaki

SUSY CP and flavor problems are central issues for SUSY scenarios with light sleptons whose masses are below or around the TeV scale. In particular, these problems are severe when SUSY is responsible for the muon g-2 anomaly: the CP problem is more difficult than naively thought, given the effects of anomaly mediation, etc. In this talk, I will introduce a CP/flavor-safe SUSY breaking mechanism using axion supermultiplet. The strong CP problem is also solved simultaneously. I will also show that the muon g-2 anomaly can indeed be explained while circumventing other phenomenological constraints.

Neutron-mirror-neutron oscillation and neutron star cooling

• Yongchao Zhang

In the dense environment of neutron stars (NSs), neutrons $n$ can transit into mirror neutrons $n’$, which exist in some mirror models. Such a transition leads to exotic energy loss of NSs via emission of photons, which sets limit on the $n-n’$ mixing parameter $\delta_{nn’} \lesssim 10^{-17}$ eV. We point out that the beta decay of mirror neutrons and the subsequent formation of clouds of mirror electrons and deuterons inside the NSs will rob energy from the normal sector via $e - e'$ scattering. Given a wide range of milli-charge parameter $\epsilon$, the energy loss of NSs will be dominated by the emission of mirror photons $\gamma’$. Then the stringent bounds of NSs on $n-n'$ transition could be relaxed.