Qi-Shu Yan

Thermodynamics of deformed AdS 5 model with a positive/negative quadratic correction in graviton-dilaton system

By solving the Einstein equations of the graviton coupling with a real scalar dilaton field, we establish a general framework to self-consistently solve the geometric background with black-hole for any given phenomenological holographic models. In this framework, we solve the black-hole background, the corresponding dilaon field and the dilaton potential for the deformed AdS5 model with a positive/negative quadratic correction. We systematically investigate the thermodynamical properties of the deformed AdS5 model with a positive and negative quadratic correction, respectively, and compare with lattice QCD on the results of the equation of state, the heavy quark potential, the Polyakov loop and the spatial Wilson loop. We find that the bulk thermodynamical properties are not sensitive to the sign of the quadratic correction, and the results of both deformed holographic QCD models agree well with lattice QCD result for pure SU(3) gauge theory. However, the results from loop operators favor a positive quadratic correction, which agree well with lattice QCD result. Especially, the result from the Polyakov loop excludes the model with a negative quadratic correction in the warp factor of AdS5.

Confront holographic QCD with Regge trajectories of vectors and axial-vectors

By matching the predictions of the Dp–Dq soft-wall model in type II superstring theory with the spectra of vector and axial-vector mesons, we show the dependence of the Regge trajectories parameters on the metric parameters of the model. From the experimental results of Regge parameters for vector mesons, it is found that the D3 background brane with both q=5 and q=7 probe brane and D4 background brane with q=4 probe brane are close to the realistic holographic QCD. We also discuss how to realize chiral symmetry breaking in the vacuum and asymptotic chiral symmetry restoration in high excitation states. We find that the constant component of the 5-dimension mass square of axial-vector mesons plays an efficient role to realize the chiral symmetry breaking, and a small negative z4 correction in the 5-dimension mass square is helpful to realize the chiral symmetry restoration in high excitation states.

A dynamical soft-wall holographic QCD model for chiral symmetry breaking and linear confinement

A self-consistent dynamical soft-wall holographic QCD model is formulated in the framework of graviton–dilaton–scalar system, which can realize both chiral symmetry breaking and confinement, two of the most important phenomena of QCD. The scalar field corresponds to the quark–antiquark condensate and can explain the property of chiral dynamics. The quadratic dilaton background field ϕ=μ2z2 as in the original soft-wall model can accommodate two aspects in the manifestation of color confinement, i.e. the Regge spectra of hadrons and the linear potential between quarks. It is observed that both the slope of the Regge spectra and the string tension of the quark potential are proportional to μ2. More interesting observation is that the best fitted value of μ is around the dynamical gluon mass extracted from lattice data. It is also shown that the negative dilaton background ϕ=−μ2z2 can be safely excluded in this framework.

Higgs pair production: Improved description by matrix element matching

Higgs pair production is crucial for measuring the Higgs boson self-coupling. The dominant channel at hadron colliders is gluon fusion via heavy-quark loops. We present the results of a fully exclusive simulation of gluon fusion Higgs pair production based on the matrix elements for hh + 0, 1 partons including full heavy-quark loop dependence, matched to a parton shower. We examine and validate this new description by comparing it with (a) Higgs Effective Theory predictions, (b) exact hh + 0-parton sample showered by pythia, and (c) exact hh+1-parton distributions, by looking at the most relevant kinematic distributions, such as PTh, PThh, Mhh spectra, and jet rate as well. We find that matched samples provide an state-of-the-art accurate exclusive description of the final state. The relevant LHE files for Higgs pair productions at the LHC can be accessed via this http URL, which can be used for relevant experimental analysis.

Probing triple-Higgs productions via

The quartic self-coupling of the Standard Model Higgs boson can only be measured by observing the triple-Higgs production process, but it is challenging for the Large Hadron Collider (LHC) Run 2 or International Linear Collider (ILC) at a few TeV because of its extremely small production rate. In this paper, we present a detailed Monte Carlo simulation study of the triple-Higgs production through gluon fusion at a 100 TeV hadron collider and explore the feasibility of observing this production mode. We focus on the decay channel

4b2\gamma

HHH\rightarrow b\bar{b}b\bar{b}\gamma\gamma

at a 100 TeV hadron collider

, investigating detector effects and optimizing the kinematic cuts to discriminate the signal from the backgrounds. Our study shows that, in order to observe the Standard Model triple-Higgs signal, the integrated luminosity of a 100 TeV hadron collider should be greater than

New Physics in multi-Higgs boson final states

1.8\times 10^4

Probe Higgs boson pair production via the 3ℓ2j + missing ET mode

ab

Discovery potential of Higgs boson pair production through final states at a 100 TeV collider

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