Analysis of the scalar doubly heavy tetraquark states with QCD sum rules

In this article, we perform a systematic study of the mass spectrum of the scalar doubly charmed and doubly bottom tetraquark states using the QCD sum rules.Comment: 17 pages, 24 figures, add more discussion

Another tetraquark structure in the π+χc1\pi^+ \chi_{c1} invariant mass distribution

In this article, we assume that there exists a scalar hidden charm tetraquark state in the $\pi^+ \chi_{c1}$ invariant mass distribution, and study its mass using the QCD sum rules. The numerical result $M_{Z}=(4.36\pm0.18) \rm{GeV}$ is consistent with the mass of the Z(4250). The Z(4250) may be a tetraquark state, other possibilities, such as a hadro-charmonium resonance and a $D_1^+\bar{D}^0+ D^+\bar{D}_1^0$ molecular state are not excluded.Comment: 14 pages, 14 figure, correct some type error

Analysis of the Y(4140) and related molecular states with QCD sum rules

In this article, we assume that there exist scalar ${D}^\ast {\bar {D}}^\ast$, ${D}_s^\ast {\bar {D}}_s^\ast$, ${B}^\ast {\bar {B}}^\ast$ and ${B}_s^\ast {\bar {B}}_s^\ast$ molecular states, and study their masses using the QCD sum rules. The numerical results indicate that the masses are about $(250-500) \rm{MeV}$ above the corresponding ${D}^\ast -{\bar {D}}^\ast$, ${D}_s^\ast -{\bar {D}}_s^\ast$, ${B}^\ast -{\bar {B}}^\ast$ and ${B}_s^\ast -{\bar {B}}_s^\ast$ thresholds, the Y(4140) is unlikely a scalar ${D}_s^\ast {\bar {D}}_s^\ast$ molecular state. The scalar $D^\ast {\bar D}^\ast$, $D_s^\ast {\bar D}_s^\ast$, $B^\ast {\bar B}^\ast$ and $B_s^\ast {\bar B}_s^\ast$ molecular states maybe not exist, while the scalar ${D'}^\ast {\bar {D'}}^\ast$, ${D'}_s^\ast {\bar {D'}}_s^\ast$, ${B'}^\ast {\bar {B'}}^\ast$ and ${B'}_s^\ast {\bar {B'}}_s^\ast$ molecular states maybe exist.Comment: 19 pages, 36 figures, slight revisio

Mass spectrum of the axial-vector hidden charmed and hidden bottom tetraquark states

In this article, we perform a systematic study of the mass spectrum of the axial-vector hidden charmed and hidden bottom tetraquark states using the QCD sum rules, and identify the $Z^+(4430)$ as an axial-vector tetraquark state tentatively.Comment: 24 pages, 38 figures, slight revisio

Analysis of the vertexes ΞQ∗ΞQ′V\Xi_Q^*\Xi'_Q V, ΣQ∗ΣQV\Sigma_Q^*\Sigma_Q V and radiative decays ΞQ∗→ΞQ′γ\Xi_Q^*\to \Xi'_Q \gamma, ΣQ∗→ΣQγ\Sigma_Q^*\to \Sigma_Q \gamma

In this article, we study the vertexes $\Xi_Q^*\Xi'_Q V$ and $\Sigma_Q^* \Sigma_Q V$ with the light-cone QCD sum rules, then assume the vector meson dominance of the intermediate $\phi(1020)$, $\rho(770)$ and $\omega(782)$, and calculate the radiative decays $\Xi_Q^*\to \Xi'_Q \gamma$ and $\Sigma_Q^*\to \Sigma_Q \gamma$.Comment: 28 pages, 4 tables, revised versio

Experimental characterization of a supercapacitor-based electrical torque-boost system for downsized ICE vehicles

The need to improve fuel economy and reduce the emission of CO2 and other harmful pollution from internal-combustion-engine vehicles has led to engine downsizing. However, downsized turbocharged engines exhibit a relatively low torque capability at low engine speeds. To overcome this problem, an electrical torque boost may be employed while accelerating and changing gear and to facilitate energy recovery during regenerative braking. This paper describes the operational requirements of a supercapacitor-based torque-boost system, outlines the design and sizing of the electrical drive-train components, and presents experimental characterization of a demonstrator system

Analysis of Ωc∗(css)\Omega_c^*(css) and Ωb∗(bss)\Omega_b^*(bss) with QCD sum rules

In this article, we calculate the masses and residues of the heavy baryons $\Omega_c^*(css)$ and $\Omega_b^*(bss)$ with spin-parity ${3/2}^+$ with the QCD sum rules. The numerical values are compatible with experimental data and other theoretical estimations.Comment: 13 pages, 8 figures, slight versio

Study of Doubly Heavy Baryon Spectrum via QCD Sum Rules

In this work, we calculate the mass spectrum of doubly heavy baryons with the diquark model in terms of the QCD sum rules. The interpolating currents are composed of a heavy diquark field and a light quark field. Contributions of the operators up to dimension six are taken into account in the operator product expansion. Within a reasonable error tolerance, our numerical results are compatible with other theoretical predictions. This indicates that the diquark picture reflects the reality and is applicable to the study of doubly heavy baryons.Comment: 23 pages, 9 figures, minor corrections in expression

Final state interactions in the decay B0→ηcK∗B^0 \to \eta_c K^*

In this article, we study the final-state rescattering effects in the decay $B^0 \to \eta_cK^*$, the numerical results indicate the corrections are comparable with the contribution from the naive factorizable amplitude, and the total amplitudes can accommodate the experimental data.Comment: 11 pages, 1 figure, revised version, to appear in EPJ

Analysis of the vector form factors fKπ+(Q2)f^+_{K\pi}(Q^2) and fKπ−(Q2)f^-_{K\pi}(Q^2) with light-cone QCD sum rules

In this article, we calculate the vector form factors $f^+_{K\pi}(Q^2)$ and $f^-_{K\pi}(Q^2)$ within the framework of the light-cone QCD sum rules approach. The numerical values of the $f^+_{K\pi}(Q^2)$ are compatible with the existing theoretical calculations, the central value of the $f^+_{K\pi}(0)$, $f^+_{K\pi}(0)=0.97$, is in excellent agreement with the values from the chiral perturbation theory and lattice QCD. The values of the $|f^-_{K\pi}(0)|$ are very large comparing with the theoretical calculations and experimental data, and can not give any reliable predictions. At large momentum transfers with $Q^2> 5GeV^2$, the form factors $f^+_{K\pi}(Q^2)$ and $|f^-_{K\pi}(Q^2)|$ can either take up the asymptotic behavior of $\frac{1}{Q^2}$ or decrease more quickly than $\frac{1}{Q^2}$, more experimental data are needed to select the ideal sum rules.Comment: 22 pages, 16 figures, revised version, to appear in Eur. Phys. J.