We suggest to study the production mechanism and some details of the production properties to probe the structure of the DDpi resonance T_cc^+ recently observed by the LHCb Collaboration. If the resonance is produced as a four-quark state, one can fi
nd the corresponding finger prints via measurements on some production properties that are the same as those of Xi_cc. The reason is that a special colour connection on the interface between the perturbative and non perturbative QCD is required for these doubly-charm hadron production. On the other hand, if T_cc^+ is produced as a hadron molecule, the measurement on the momentum correlation of DD^* can be a smoking gun to make the judgement. The present data favour a compact four-quark state production via the cc diquark fragmentation.
In the framework of the perturbative Quantum Chromodynamics factorization, the cross section of the heavy meson production via the combination of a heavy quark with a light one can be factorized to be the convolution of the combination matrix element
, the light quark distribution function, and the hard partonic sub-cross section of the heavy quark production. The partonic distribution and the combination matrix element are functions of a scaling variable, respectively, which is the momentum fraction of the corresponding quark with respect to the heavy meson. We studied the $D^{*pm}$ production in jet via combination in pp collision at the LHC. Our calculation can be summed with the fragmentation contribution, and the total result is comparable with the experimental data. The combination matrix elements can be further studied in various hadron production processes.
We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak. At the second order of QCD coupling, we consider the exact calculation of flavour-singlet contribut
ions where the Higgs boson couples to the internal top and bottom quark. Helpful information on the running mass effects related to Yukawa coupling may be obtained by analyzing this process. High precision production for $hto cbar{c}$ within the SM makes it possible to search for new physics that may induce relatively large interactions related to the charm quark. As an example, we evaluate the axion-like particle associate production with a charm quark pair in the Higgs decay and obtain some constraints for the corresponding parameters under some assumptions.
We calculate the masses of the $QQbar{q}bar{q}$ ($Q=c,b$; $q=u,d,s$) tetraquark states with the aid of heavy diquark-antiquark symmetry (HDAS) and the chromomagnetic interaction (CMI) model. The masses of the highest-spin ($J=2$) tetraquarks that hav
e only the $(QQ)_{bar{3}_c}(bar{q}bar{q})_{3_c}$ color structure are related with those of conventional hadrons using HDAS. Thereafter, the masses of their partner states are determined with the mass splittings in the CMI model. Our numerical results reveal that: (i) the lightest $ccbar{n}bar{n}$ ($n=u,d$) is an $I(J^P)=0(1^+)$ state around 3929 MeV (53 MeV above the $DD^*$ threshold) and none of the double-charm tetraquarks are stable; (ii) the stable double-bottom tetraquarks are the lowest $0(1^+)$ $bbbar{n}bar{n}$ around 10488 MeV ($approx116$ MeV below the $BB^*$ threshold) and the lowest $1/2(1^+)$ $bbbar{n}bar{s}$ around 10671 MeV ($approx20$ MeV below the $BB_s^*/B_sB^*$ threshold); and (iii) the two lowest $bcbar{n}bar{n}$ tetraquarks, namely the lowest $0(0^+)$ around 7167 MeV and the lowest $0(1^+)$ around 7223 MeV, are near-threshold states. Moreover, we discuss the constraints on the masses of double-heavy hadrons. Specifically, for the lowest nonstrange tetraquarks, we obtain $T_{cc}<3965$ MeV, $T_{bb}<10627$ MeV, and $T_{bc}<7199$ MeV.
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.
We have systematically investigated the mass spectrum and rearrangement decay properties of the exotic tetraquark states with four different flavors using a color-magnetic interaction model. Their masses are estimated by assuming that the $X(4140)$ i
s a $csbar{c}bar{s}$ tetraquark state and their decay widths are obtained by assuming that the Hamiltonian for decay is a constant. According to the adopted method, we find that the most stable states are probably the isoscalar $bsbar{u}bar{d}$ and $csbar{u}bar{d}$ with $J^P=0^+$ and $1^+$. The width for most unstable tetraquarks is about tens of MeVs, but that for unstable $cubar{s}bar{d}$ and $csbar{u}bar{d}$ can be around 100 MeV. For the $X(5568)$, our method cannot give consistent mass and width if it is a $bubar{s}bar{d}$ tetraquark state. For the $I(J^P)=0(0^+),0(1^+)$ double-heavy $T_{bc}=bcbar{u}bar{d}$ states, their widths can be several MeVs.
Investor attention is an important concept in behavioral finance. Many articles have conducted cross-disciplinary research leading by this concept. In this paper, we use data extraction technology to collect a large number of Baidu Index keyword sear
ch volume data. After analyzing the data, we draw a conclusion that has not been paid attention to in all the past research. We find heterogeneity in searching by internet users in China. Firstly, in terms of search behavior, internet users are more inclined to use the PC end to obtain information when facing areas which need to be taken seriously by them. Secondly, attention is heterogeneous while searching. When Internet users search for information in mobile end, their attention is divergent, and search for seemingly unrelated keywords at the same time which limits their attention to information.
Dark sector may couple to the Standard Model via one or more mediator particles. We discuss two types of mediators: the dark photon $A^{prime}$ and the dark scalar mediator $phi$. The total cross-sections and various differential distributions of the
processes $e^{+} e^{-} rightarrow q bar{q} A^{prime}$ and $e^{+} e^{-} rightarrow q bar{q} phi$ ($q=u,~d,~c,~s$ and $b$ quarks) are discussed. We focus on the study of the invisible $A^{prime}$ due to the cleaner background at future $e^{+} e^{-}$ colliders. It is found that the kinematic distributions of the two-jet system could be used to identify (or exclude) the dark photon and the dark scalar mediator, as well as to distinguish between them. We further study the possibility of a search for dark photons at a future CEPC experiment with $sqrt{s}=$ 91.2 GeV and 240 GeV. With CEPC running at $sqrt{s}=$ 91.2 GeV, it would be possible to perform a decisive measurement of the dark photon (20 GeV $< m_{A^{prime}} <$ 60 GeV) in less than one operating year. The lower limits of the integrated luminosity for the significance $S/sqrt{B}=$ 2$sigma$, 3$sigma$ and 5$sigma$ are presented.
A completely relativistic quark model in the Bethe-Salpter framework is employed to calculate the exclusive production ratio of the neutral over charged Kaon pair in $e^+e^-$ annihilation continuum region for center of mass energies smaller than the
$J/Psi$ mass. The valence quark charge plays the key r^{o}le. The cancellation of the diagrams for the same charge case (in $K_S + K_L$) and the non-cancellation of the diagrams for the different charge case (in $K^-+K^+$) lead to the ratio as $(m_s-m_d)^2/M_{Kaon}^2 sim 1/10$.
