arXiv subjects

Mingshui Chen

Publications and source records attributed to Mingshui Chen.

5 recordsLinked to original sources

arXiv2025

New Physics Search at the CEPC: a General Perspective

The Circular Electron-Positron Collider (CEPC), a proposed next-generation Higgs factory, provides new opportunities to explore physics beyond the Standard Model (SM). With its clean electron-positron collision environment and the ability to collect large samples of Higgs, W, and Z bosons, the CEPC enables precision measurements and searches for new physics. This white paper outlines the CEPC's discovery potential, including studies of exotic decays of the Higgs, Z, and top quarks, dark matter and dark sector phenomena, long-lived particles, supersymmetry, and neutrino-related signatures. Advanced detector technologies and reconstruction techniques, such as one-to-one correspondence reconstruction and jet origin identification, significantly improve sensitivity to rare and weakly interacting processes. The CEPC is particularly well suited to probe the electroweak phase transition and test models of electroweak baryogenesis and dark sector interactions. In addition, global fit analyses highlight the CEPC's complementary role in constraining a wide range of new physics scenarios. These features position the CEPC as a powerful tool for exploring the next frontier in fundamental particle physics in the post-Higgs discovery era.

hep-ex↗

arXiv2025

Flavor Physics at the CEPC: a General Perspective

We discuss the landscape of flavor physics at the Circular Electron-Positron Collider (CEPC), based on the nominal luminosity outlined in its Technical Design Report. The CEPC is designed to operate in multiple modes to address a variety of tasks. At the $Z$ pole, the expected production of 4 Tera $Z$ bosons will provide unique and highly precise measurements of $Z$ boson couplings, while the substantial number of boosted heavy-flavored quarks and leptons produced in clean $Z$ decays will facilitate investigations into their flavor physics with unprecedented precision. We investigate the prospects of measuring various physics benchmarks and discuss their implications for particle theories and phenomenological models. Our studies indicate that, with its highlighted advantages and anticipated excellent detector performance, the CEPC can explore beauty and $τ$ physics in ways that are superior to or complementary with the Belle II and Large-Hadron-Collider-beauty experiments, potentially enabling the detection of new physics at energy scales of 10 TeV and above. This potential also extends to the observation of yet-to-be-discovered rare and exotic processes, as well as testing fundamental principles such as lepton flavor universality, lepton and baryon number conservation, etc., making the CEPC a vibrant platform for flavor physics research. The $WW$ threshold scan, Higgs-factory operation and top-pair productions of the CEPC further enhance its merits in this regard, especially for measuring the Cabibbo-Kobayashi-Maskawa matrix elements, and Flavor-Changing-Neutral-Current physics of Higgs boson and top quarks. We outline the requirements for detector performance and considerations for future development to achieve the anticipated scientific goals.

hep-ex↗

arXiv2013

The role of interference in unraveling the ZZ-couplings of the newly discovered boson at the LHC

We present a general procedure for measuring the tensor structure of the coupling of the scalar Higgs-like boson recently discovered at the LHC to two Z bosons, including the effects of interference among different operators. To motivate our concern with this interference, we explore the parameter space of the couplings in the effective theory describing these interactions and illustrate the effects of interference on the differential dilepton mass distributions. Kinematic discriminants for performing coupling measurements that utilize the effects of interference are developed and described. We present projections for the sensitivity of coupling measurements that use these discriminants in future LHC operation in a variety of physics scenarios.

hep-ph↗

arXiv2013

Combination and Standar Model Scalar Boson Properties in CMS

Combination results of the recently discovered boson are presented using data samples corresponding to integrated luminosities of up to 5.1 $\invfb$ at 7 TeV and up to 12.2 $\invfb$ at 8 TeV of proton-proton collisions collected with CMS experiment at LHC. The significance of the new boson is 6.9 $σ$ with mass measured to be 125.8 $\pm$ 0.4 (stat) $\pm$ 0.4 (syst). The event yields obtained by the different analyses targeting specific decay modes and production mechanisms are consistent with those predicted for the stand model (SM) Higgs boson. The best-fit signal strength for all channels combined, expressed in units of the SM Higgs boson cross section, is 0.88 $\pm$ 0.21 at the measured mass. The consistency of the couplins of the observed boson with those expected for the SM Higgs boson is tested in various ways, and no significant deviations are found. Results on the test of different spin-parity hypotheses of the observed boson are also shown, but with updated data samples corresponding to integrated luminosities of 5.1 $\invfb$ at 7 TeV and 19.6 $\invfb$ at 8 TeV in two channels H $\rightarrow$ WW $\rightarrow~2\ell2ν$ and H $\rightarrow$ ZZ $\rightarrow~4\ell$ separately. Under the assumption that the observed boson has spin 0 and positive parity, the pure scalar hypothesis is found to be consistent with the observed boson when compared to other tested spin-parity hypotheses. The data in the H $\rightarrow$ ZZ $\rightarrow~4\ell$ channel disfavor the pseudo-scalar hypothesis $0^-$ with a CLs value of 0.16$%$, disfavor the pure spin-2 hypothesis of a narrow resonance with the minimal couplings to the vector bosons with a CLs value of 1.5$%$, and disfavor the pure spin-1 hypothesis with even smaller CLs value.

hep-ex↗

arXiv2012

Precision studies of the Higgs boson decay channel H -> ZZ -> 4l with MEKD

The importance of the H -> ZZ -> 4l "golden" channel was shown by its major role in the discovery, by the ATLAS and CMS collaborations, of a Higgs-like boson with mass near 125 GeV. We analyze the discrimination power of the matrix element method both for separating the signal from the irreducible ZZ background and for distinguishing various spin and parity hypotheses describing a signal in this channel. We show that the proper treatment of interference effects associated with permutations of identical leptons in the four electron and four muon final states plays an important role in achieving the best sensitivity in measuring the properties of the newly discovered boson. We provide a code, MEKD, that calculates kinematic discriminants based on the full leading order matrix elements and which will aid experimentalists and phenomenologists in their continuing studies of the H -> ZZ -> 4l channel.

hep-ph↗