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Zhong-Juan Yang

Publications and source records attributed to Zhong-Juan Yang.

13 recordsLinked to original sources
arXiv2025

Production of doubly charmed tetraquark $T_{cc}$ via photon-photon fusion at electron-positron colliders

Within a phenomenological diquark fragmentation model, we study the production of doubly charmed tetraquark $T_{cc}$ via photon-photon fusion at electron-positron colliders. The production of $T_{cc}$ is divided into two steps: the perturbative production of heavy $(cc)$-diquark and its nonperturbative hadronization. Two diquark configurations of $(cc)[^3S_1]_{\bar{3}}$ and $(cc)[^1S_0]_{6}$ are considered, and the $(cc)[^3S_1]_{\bar{3}}$ state dominates the produciotn of $T_{cc}$. We discuss two hadronization models of $(cc)[^3S_1]_{\bar{3}}$ intermediate state into the tetraquark $T_{cc}$. It is found that it is promising to observe the tetraquark $T_{cc}$ via photon-photon fusion process both at the Circular Electron Positron Collider (CEPC) and the International Linear Collider (ILC). We find that the cross sections are sensitive to constituent charm quark mass of diquark, and they also have strong dependence on the hadronization models.

hep-ph↗
arXiv2024

Phenomenological study of heavy neutral gauge boson in the left-right symmetric model at future muon collider

The exotic neutral gauge boson is a powerful candidate for the new physics beyond the standard model. As a promising model, the left-right symmetric model has been proposed to explain the neutrino mass, dark matter, and matter-antimatter asymmetry, etc., in which exotic gauge bosons $Z^\prime, W^{\prime \pm}$ have been put forward as well as other new right-handed particles. We investigate the $μ^+ μ^- \to q\bar{q} $ and $ μ^+ μ^- \to l^+ l^- $ processes involving the $Z^\prime$ boson as an intermediate particle. The coupling strength, decay width and mass are the key parameters on the production and decay processes of the $Z^\prime$ boson. The results indicate that the angular distributions of final particles are sensitive to the couplings of $Z^\prime$ to the other fermions. Asymmetries defined from the angular distributions are ideal quantities to demonstrate the discrepancy between the standard model process and the processes with $Z^\prime$ participated and they are also appropriate observables to discriminate the couplings of $Z^\prime$ to other particles. Compared with the current results at the Large Hadron Collider (LHC), the future muon collider has a great potential to explore the new parameter space with $Z^\prime$ boson.

hep-ph↗
arXiv2021

Doubly Charged Higgs Production at Future $ep$ Colliders

The Higgs sector of the standard model can be extended by introducing an $SU(2)_L$ Higgs triplet $Δ$ to generate the tiny neutrino masses in the framework of type-II seesaw mechanism. In this paper, we study the pair production of the introduced Higgs triplet at future $e^{-}p$ colliders. The corresponding production cross sections via vector boson fusion process at FCC-ep and ILC$\otimes$FCC are predicted, where the production of a pair of doubly charged Higgs is found to be dominant and then used to investigate the collider phenomenology of the Higgs triplet. Depending on the size of the Higgs triplet vacuum expectation value, the doubly charged Higgs may decay into a pair of same-sign charged leptons or a pair of same-sign $W$ bosons. In order to explore the discovery potential of the doubly charged Higgs at future $e^{-}p$ colliders, we discuss these two decay scenarios in detail and show respectively the detection sensitivity on the mass of the doubly charged Higgs.

hep-ph↗
arXiv2020

Doubly Heavy Baryon Xi_cc Production in Upsilon (1S) Decay

Upsilon (1S) decay to Xi_cc +anything is studied. It is shown that the branching ratio can be as significant as that of Upsilon (1S) decay to J/Psi +anything. The non-relativistic heavy quark effective theory framework is employed for the calculation on the decay width. Measurements on the production of Xi_cc and likely production characteristic of the partonic state with four charm quarks at BELLE2 are suggested.

hep-ph↗
arXiv2018

Higgs production in association with bottom quark pair at LHC

The direct observation of the Yukawa interaction related to Standard Model Higgs and the bottom quark is obtained from the $h\to b\bar{b}$ process recently. The b-tagging becomes an important tool to search for new heavy resonance production at LHC. We use the b-tagging method to investigate the neutral Higgs production in association with a bottom quark pair, and perform the detector simulation for the signal process with the Higgs decaying into $b\bar{b}$ or $τ^+τ^-$ together with the dominant backgrounds. Our results show that $b\bar{b}b\bar{b}$ and $b\bar{b}τ^+τ^-$ processes will play an important role to search for the exotic heavy Higgs production at LHC and future hadron colliders.

hep-ph↗
arXiv2018

Search for $W^{\prime}$ signal in single top quark production at LHC

The heavy charged gauge bosons were proposed in the theories beyond standard model. We explore the discovery potential for $W'\to t\bar{b}$ with top quark semi-leptonic decay at the LHC. We concentrate on the new physics signal search with the deviation from the standard model prediction if the resonance peak of $W'$ can not be observed directly. The events of signal with two jets plus one charged lepton and missing energy are simulated together with the dominant standard model backgrounds. In this paper, it is found that suitable cuts on the kinematic observables can effectively suppress the standard model backgrounds, so that it is possible to search for $W'$ signal at the LHC with its mass less than 6.6 TeV.

hep-ph↗
arXiv2014

The Production of $Ξ_{bb}$ at Photon Collider

The inclusive production of the doubly heavy baryon $Ξ_{bb}$ is investigated at polarized and unpolar- ized photon collider. bb pair in both color triplet and sextet have been considered to transform into $Ξ_{bb}$. The results indicate that the contribution from color sextet is about 8% for $Ξ_{bb}$ production. For the ILC collision energy ranging from 91GeV to 1000GeV, the total cross section of $Ξ_{bb}$ shows a downtrend, i.e., the production of $Ξ_{bb}$ has the maximal rate at $\sqrt S = 91GeV$. Our results indicate that the initial beam polarization may be an important asset for the production of $Ξ_{bb}$. At some collision point, the production rate of $Ξ_{bb}$ can be increased about 17% with an appropriate choice of the initial beam polarization.

hep-ph↗
arXiv2014

Search for $W^\prime$ signal via $tW^\prime$ associated production at LHC

A variety of new physics models predict the existence of extra charged gauge bosons ($W^\prime$). It is verified that $W^\prime$ and top quark associated production is a promising process to search for $W^\prime$ signal at the LHC. We study the collider signatures of multi-jets$+$lepton$+\met$ by reconstructing the $tW'$ intermediate state through the decay modes of $W^\prime \to tb$, $W^\prime \to q \bar q'$ and $W^\prime \to l ν$ respectively. An angular distribution related to charged lepton and top quark moving direction is provided to distinguish alternative left-handed or right-handed chiral couplings of $W^\prime$ to quarks in the hadronic decay modes. The superiority on the search of $W^\prime$ is demonstrated in the leptonic decay channel for the left-handed type interaction, which is forbidden for the right-handed type interaction in the most theories. To be more realistic, the relevant standard model backgrounds are simulated. We adopt various kinematic cuts to suppress the backgrounds and collect the integral luminosity needed for the corresponding process detected at the LHC with $3σ$ sensitivity. We also provide a forward-backward asymmetry which is related to the chirality of $W^\prime$. The successive studies can shed light on the potential searching for $W^\prime$ signal as well as distinguishing typical new physics models.

hep-ph↗
arXiv2014

Colour connections of four quark $Q\bar{Q}Q'\bar{Q}'$ system and doubly heavy baryon production in $e^{+}e^{-}$ annihilation

The hadronization effects induced by various colour connections of the four quark system in $e^{+}e^{-}$ annihilation are briefly reviewed. A special colour connection of four heavy quark system without colour-separation favours the production of doubly heavy baryons. For the related three-jet case, the corresponding hadronization has not been considered. We argue that it can be effectively described as two string fragmentation besides the leading heavy diquark fragmentation. The production rate and the properties of final state hadron systems are discussed. Emphasis is on the string effect as a finger print of this hadronization procedure.

hep-ph↗
arXiv2013

Search for $Z'$ via $ZH$ associated production at LHC

Many new physics models predict the existence of extra neutral gauge bosons ($Z'$). Inspired by the recent development on Higgs search, we study the properties of $Z'$ via the Higgs and $Z$ boson associated production. The couplings of $Z'$ to quarks can be investigated through $pp \to Z'\to ZH\to l^+l^-b \bar b$ process, which also provides extraordinary signal for understanding the properties of $Z'ZH$ interaction. The standard model background processes can be significantly suppressed by adopting appropriate kinematic cuts. The charged lepton angular distributions are related to the ratio of chiral couplings of $Z'$ to quarks via $Z'ZH$ interaction.

hep-ph↗
arXiv2009

Unparticle Effects on Top Quark Pair Production at Photon Collider

The unparticle effects on $t\bar t$ production at the future photon collider are investigated. Distributions of $t\bar t$ invariant mass and that for transverse momentum of top quark with respect to Standard Model and unparticle production are predicted. An odd valley with scalar unparticle contribution appears for some values of $d_{\U}$, which is due to the big cancellation between the contribution from SM and that from unparticle. This character may be used to study the properties of scalar unparticle. Our investigations also show that scalar unparticle may play a significant role in $t \bar t$ production at photon collider if it exists.

hep-ph↗
arXiv2006

Colour Connection and Diquark Fragmentation in e^+e^- \to c \bar c q \bar q \to h's Process

The hadronization effects induced by different colour connections of $c\bar{c}q\bar{q}$ system in $e^+e^-$ annihilation are investigated by a toy model where diquark fragmentation is employed based on Pythia. It is found that the correlations between the charm baryons and charm antibaryons produced via diquark pair fragmentation are much stronger, and their momentum spectra are harder than those from the standard colour connection in Pythia.

hep-ph↗