Masses for the $(Q\bar{s})^{(*)}(\bar{Q}s)^{(*)}$ ($Q=c$ or $b$) molecular states are systematically computed in the framework of QCD sum rules. Technically, contributions of the operators up to dimension six are included in operator product expansion (OPE). The numerical result $4.13\pm0.10 {GeV}$ for $D_{s}^{*}\bar{D}_{s}^{*}$ agrees well with the mass $4143.0\pm2.9\pm1.2 {MeV}$ for Y(4140), which supports the $D_{s}^{*}\bar{D}_{s}^{*}$ molecular configuration for Y(4140).
Recently, a QCD sum-rule analysis of tetraquark molecular states has been published, having the objective of demonstrating that our previously formulated tetraquark-adequate QCD sum rules are not correct. This comment brings to the attention of the reader inconsistencies in that article and explains some subtle details of QCD sum rules for exotic states.
In "Landau equation and QCD sum rules for the tetraquark molecular states", I list out six reasons to refute the assertion of Lucha, Melikhov and Sazdjian. In "Comment on "Landau equation and QCD sum rules for the tetraquark molecular states"", they refute my viewpoint. If they want to the refute my viewpoint robustly, they should refute the six reasons one by one, and provide at least one example to illustrate that they have obtained reliable QCD sum rules for the tetraquark states and free two-meson states, respectively.
In this article, we assign the $Y(4390)$ and $Y(4220)$ to be the vector molecular states $D\bar{D}_1(2420)$ and $D^*\bar{D}_0^*(2400)$, respectively, and study their masses and pole residues with the QCD sum rules in details. The present calculations only favor assigning the $Y(4390)$ to be the $D\bar{D}_1(1^{--})$ molecular state.
We systematically investigate the mass spectra of $\{Q\bar{s}\}\{\bar{Q}^{(')}s\}$ molecular states in the framework of QCD sum rules. The interpolating currents representing the molecular states are proposed. Technically, contributions of the operators up to dimension six are included in operator product expansion (OPE). The masses for molecular states with various $\{Q\bar{s}\}\{\bar{Q}^{(')}s\}$ configurations are presented. The result $4.36\pm0.08 GeV$ for the $D_{s}^{*}\bar{D}_{s0}^{*}$ molecular state is consistent with the mass $4350^{+4.6}_{-5.1}\pm0.7 MeV$ of the newly observed $X(435…
In the present work, we investigate the scalar, axialvector and tensor doubly-charmed tetraquark molecular states without strange, with strange and with doubly-strange via the QCD sum rules, and try to make assignment of the $T^+_{cc}$ from the LHCb collaboration in the scenario of molecular states. The predictions favor assigning the $T^+_{cc}$ to be the lighter $DD^{*}$ molecular state with the spin-parity $J^P=1^+$ and isospin $I=0$, while the heavier $DD^{*}$ molecular state with the spin-parity $J^P=1^+$ and isospin $I=1$ still escapes experimental detections, the observation of the heavi…
QCD sum-rules are employed to determine whether the X(3872) can be described as a mixed state that couples to $J^{PC}=1^{++}$ charmonium hybrid and $\bar D D^*$ molecular currents. After calculating the mixed correlator of hybrid and molecular currents, we formulate the sum-rule in terms of a mixing parameter that interpolates between the pure molecular and hybrid scenarios. As the mixing parameter is increased from the pure molecular case, the predicted mass increases until it reaches a maximum value in good agreement with the X(3872) and the resulting sum-rule analysis appears more robust th…
In this article, we construct the color-singlet-color-singlet type currents and the color-singlet-color-singlet-color-singlet type currents to study the scalar $D^*\bar{D}^*$, $D^*D^*$ tetraquark molecular states and the vector $D^*D^*\bar{D}^*$, $D^*D^*D^*$ hexaquark molecular states with the QCD sum rules in details. In calculations, we choose the pertinent energy scales of the QCD spectral densities with the energy scale formula $μ=\sqrt{M^2_{T}-(2{\mathbb{M}}_c)^2}$ and $\sqrt{M^2_{H}-(3{\mathbb{M}}_c)^2}$ for the tetraquark and hexaquark molecular states respectively in a consistent way. …
In this article, we tentatively assign the $P_c(4312)$ to be the $\bar{D}Σ_c$ pentaquark molecular state with the spin-parity $J^P={\frac{1}{2}}^-$, and discuss the factorizable and non-factorizable contributions in the two-point QCD sum rules for the $\bar{D}Σ_c$ molecular state in details to prove the reliability of the single pole approximation in the hadronic spectral density. We study its two-body strong decays with the QCD sum rules, special attentions are paid to match the hadron side with the QCD side of the correlation functions to obtain solid duality. We obtain the partial decay wid…
In this work, we construct the color-singlet-color-singlet type six-quark pseudoscalar current to investigate the $\overlineΞ_{cc}Ξ_{cc}$ hexaquark molecular state with the QCD sum rules, the predicted mass $M_X \sim 7.2\,\rm{GeV}$ supports assigning the $X(7200)$ to be the $\overlineΞ_{cc}Ξ_{cc}$ hexaquark molecular state with the quantum numbers $J^{PC}=0^{-+}$. The $X(7200)$ can decay through fusions of the $\bar{c}c$ and $\bar{q}q$ pairs, we can search for the $X(7200)$ and explore its properties in the $J/ψJ/ψ$, $χ_{c1}χ_{c1}$, $D^*\bar{D}^*$ and $D_1\bar{D}_1$ invariant mass spectrum in …
In this article, we study the $\bar{D}Σ_c$, $\bar{D}Σ_c^*$, $\bar{D}^{*}Σ_c$ and $\bar{D}^{*}Σ_c^*$ pentaquark molecular states with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension $13$ in a consistent way. The present calculations support assigning the $P_c(4312)$ to be the $\bar{D}Σ_c$ pentaquark molecular state with $J^P={\frac{1}{2}}^-$, assigning the $P_c(4380)$ to be the $\bar{D}Σ_c^*$ pentaquark molecular state with $J^P={\frac{3}{2}}^-$, assigning the $P_c(4440/4457)$ to be the $\bar{D}^{*}Σ_c$ pentaquark molecular state with $…
In this work, we study the $D\bar{D}$, $DD$, $D\bar{D}_s$, $DD_s$, $D_s\bar{D}_s$ and $D_sD_s$ tetraquark molecular states with the $J^{PC}=0^{++}$ via the QCD sum rules. The prediction $M_{D_s\bar {D}_s} = 3.98\pm0.10\, \rm{GeV}$ is in very good agreement with the experimental value $M_{X(3960)} = 3956 \pm 5\pm 10 \,\rm{MeV}$ from the LHCb collaboration and supports assigning the $X(3960)$ as the $D_s^+D_s^-$ molecular state with the $J^{PC}=0^{++}$. We take account of our previous works on the four-quark states consisting of two color-neutral clusters, and acquire the mass spectrum of the gr…
In this article, we calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion, and study the $J^{PC}=0^{++}$, $1^{+-}$, $2^{++}$ $D^*\bar{D}^*$, $D_s^*\bar{D}_s^*$, $B^*\bar{B}^*$, $B_s^*\bar{B}_s^*$ molecular states with the QCD sum rules. In calculations, we use the formula $μ=\sqrt{M^2_{X/Y/Z}-(2{\mathbb{M}}_Q)^2}$ to determine the energy scales of the QCD spectral densities. The numerical results favor assigning the $Z_c(4020)$ and $Z_c(4025)$ as the $J^{PC}=0^{++}$, $1^{+-}$ or $2^{++}$ $D^*\bar{D}^*$ molecular states, the $Y(4140)$ as the …
In this article, we investigate the $\bar{D}Σ_c$, $\bar{D}Ξ^\prime_c$, $\bar{D}Σ_c^*$, $\bar{D}Ξ_c^*$, $\bar{D}^{*}Σ_c$, $\bar{D}^{*}Ξ^\prime_c$, $\bar{D}^{*}Σ_c^*$ and $\bar{D}^{*}Ξ_c^*$ pentaquark molecular states with strangeness and without strangeness via the QCD sum rules at length, pay much attention to the light flavor $SU(3)$ breaking effects, and make predictions for new pentaquark molecular states besides assigning the $P_c(4312)$, $P_c(4380)$, $P_c(4440)$, $P_c(4457)$ and $P_{cs}(4459)$ self-consistently. We can search for those pentaquark molecular states in the decays of the $Λ_b…
In this talk, we give a short review of our recent works on studying the singly heavy baryon, doubly heavy baryon, and triply heavy baryon spectra from QCD sum rules.
We use the method of QCD Sum Rules to estimate the masses of the charm baryon, $Λ^+_c$, bottom baryon $Λ^0_b$, strange baryon $Λ^0_s$ and compare them to their experimental values.
In this work, we tentatively identify the $P_{cs}(4338)$ as the $\bar{D}Ξ_c$ molecular state, and distinguish the isospins of the current operators to explore the $\bar{D}Ξ_c$, $\bar{D}Λ_c$, $\bar{D}_sΞ_c$, $\bar{D}_sΛ_c$, $\bar{D}^*Ξ_c$, $\bar{D}^*Λ_c$, $\bar{D}^*_sΞ_c$ and $\bar{D}^*_sΛ_c$ molecular states without strange, with strange and with double strange in the framework of the QCD sum rules in details. The present explorations favor identifying the $P_{cs}(4338)$ ($P_{cs}(4459)$) as the $\bar{D}Ξ_c$ ($\bar{D}^*Ξ_c$) molecular state with the spin-parity $J^P={\frac{1}{2}}^-$ (${\frac{3}…
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^…
This is an extension of the prediction of strange baryon decays to the decays of charmed baryons using QCD Sum Rules. Using QCD Sum Rules we estimate the decay $Λ^+_c (udc) \rightarrow Λ^o_s(uds)+ π^+$. Although some weak decays of the $Λ^+_c$ have been measured, since it is difficult to measure $Λ^+_c \rightarrow Λ^o_s+ π^+$ our estimates should be useful for future experiments
QCD one-loop corrections to the semileptonic process $e^+ e^- \to μ^- \bar ν_μu \bar d$ are computed. We compare the exact calculation with a ``naive'' approach to strong radiative corrections which has been widely used in the literature and discuss the phenomenological relevance of QCD contributions for LEP2 and NLC physics.
We discuss the QCD constraints on e+e- --> baryon-anti-baryon close to threshold, in light of the puzzling experimental data which indicate that close to threshold sigma (e+e- --> n n-bar) > sigma (e+e- --> p p-bar). We focus on the process e+e- --> Delta Delta-bar, which is particularly simple from the theoretical point of view. In this case it is possible to make exact QCD predictions for the relative yields of the four members of the Delta multiplet, modulo one crucial dynamical assumption.
Masses of the p-wave excited heavy baryons have been calculated to the Lambda_{QCD}/m_Q order using QCD sum rule method within the framework of heavy quark effective theory. Numerical results for kinetic energy lambda_1 and chromo-magnetic interaction lambda_2 are presented. The splitting between spin 1/2 and 3/2 doublet derived from our calculation is given, for which the agreement with the current experiment is desirable.
We report on state-of-the-art theoretical predictions for $pp\to t\bar{t}b\bar{b}$ including full off-shell effects in the di-lepton decay channel at NLO QCD accuracy. We briefly discuss the impact of NLO QCD corrections on differential distributions and also asses theoretical uncertainties from scale and PDF dependence. Furthermore, we propose a simple kinematic reconstruction in order to distinguish $b$ jets originating from top-quark decays from arising from gluon splittings.
The quarks and gluons are confined objects, they cannot be put on the mass-shell, it is questionable to apply the Landau equation to study the Feynman diagrams in the QCD sum rules. Furthermore, we carry out the operator product expansion in the deep Euclidean region $p^2\to -\infty$, where the Landau singularities cannot exist. The Landau equation servers as a kinematical equation in the momentum space, and is independent on the factorizable and nonfactorizable properties of the Feynman diagrams in the color space. The meson-meson scattering state and tetraquark molecular state both have four…
We report on our computation of the mixed QCD and weak corrections to $q {\bar q} \to t\bar{t}$ including $t, \bar t$ spin effects, in particular on single top spin asymmetries.
We calculate the magnetic moments of Delta baryons within the framework of QCD sum rules. A comparison of our results on the magnetic moments of the Delta baryons with the predictions of different approaches is presented.
We investigate the electric polarizabilities of neutral baryons using the method of QCD sum rules. The diagrams in the operator product expansion are taken into account up to dimension 6. We obtain different values of the polarizabilities among hyperons, the ordering of which is given $\barα_n>\barα_{Ξ^0}>\barα_Λ$. The polarizability of ${Σ^0}$, $\barα_{Σ^0}$, has possibly a very small value.
We give an overview over recent calculations of baryonic correlator functions with finite mass quarks in view on their applicability for QCD sum rules. The QCD sum rule method is then demonstrated within the Heavy Quark Effective Theory.
We discuss an application of QCD sum rules to the heavy baryons $Λ_Q$ and $Σ_Q$. The predictions for the masses of heavy baryons, residues and Isgur-Wise function are presented. The new results on two loop anomalous dimensions of baryonic currents and QCD radiative corrections (two- and three- loop contributions) to the first two Wilson coefficients in OPE are explicitly presented.
We have computed the cross section for $t\bar t$ production by gluon-gluon fusion at next-to-leading order (NLO) in the QCD coupling, keeping the full dependence on the $t\bar t$ spins. Furthermore we have determined to the same order the spin dependent cross sections for the processes $g + q ({\bar q})\to t {\bar t} + q ({\bar q})$. Together with our previous results for $q + {\bar q} \to t {\bar t} (g)$ these results allow for predictions, at NLO QCD, of the hadronic production of $t\bar t$ pairs in a general spin configuration. As an application we have determined the degree of correlation …
Using the QCD sum rules method, we estimate the mass and residues of the first radial excitations of octet baryons. The contributions coming from the ground state baryons are eliminated by constructing the linear combinations of the sum rules corresponding to different Lorentz structures. Our predictions of the masses of the first radial excitations of octet baryons are in good agreement with the data.
We perform a systematic study of the masses of charmed and bottom baryons in the framework of the QCD sum rule approach. Contributions of the operators up to dimension six are included in operator product expansion. The resulting heavy baryon masses from the calculations are well consistent with the experimental values, and predictions to the spectroscopy of the unobserved bottom baryons are also presented.
In this contribution we report on the latest theoretical predictions for $t\bar{t}b\bar{b}$. These results are obtained for the fully decayed final state $pp \rightarrow e^+ ν_e μ^- ν_μ b \bar{b} b \bar{b}$ at next-to-leading order accuracy in QCD. We present predictions with full off-shell effects and in the Narrow Width Approximation. Specifically, we report on the size of the NLO QCD corrections and the size of the full off-shell effects. Finally, we study the nature of the $b$-jets present in the final state.
In this article, we restudy the mass spectrum of the ground state triply-heavy baryon states with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension 6 in a consistent way and preforming a novel analysis. It is the first time to take into account the three-gluon condensates in the QCD sum rules for the triply-heavy baryon states.
We compute the diagonal isovector axial-vector as well as induced pseudoscalar form factors of nucleon, $Σ$ and $Ξ$ baryons by employing the light-cone QCD sum rules to leading order in QCD and including distribution amplitudes up to twist 6. Extrapolating our sum-rules results to low-momentum transfers, we make a comparison with experimental and lattice-QCD results where we can achieve a nice qualitative and quantitative agreement.
The magnetic moments of heavy sextet $J^P = {1\over 2}^+$ baryons are calculated in framework of the light cone QCD sum rules method. Linearly independent relations among the magnetic moments of these baryons are obtained. The results for the magnetic moments of heavy baryons obtained in this work are compared with the predictions of the other approaches.
We present a full off-shell NLO QCD calculation of $pp \rightarrow e^+ ν_e b μ^- \barν_μ\bar{b} b \bar{b} + X$. Results are obtained using the HELAC-NLO Monte Carlo framework. We discuss a comparison to previous results and to experimental measurements. We also investigate the contribution of the initial states involving $b$-quarks and we introduce two $b$-jet tagging schemes.
Octet baryon magnetic moments are calculated in framework of the light cone QCD sum rules. The analysis is carried for the general form of the interpolating currents for octet baryons. A comparison of our results on the magnetic moments of octet baryons with the predictions of other approaches and experimental data is presented.
QCD one-loop corrections to the full gauge invariant set of electroweak diagrams describing the hadronic process $e^+ e^- \to u~\bar d~s~\bar c$ are computed. Four-jet shape variables for $WW$ events are studied at next-to-leading order and the effects of QCD corrections on the determination of the $W$--mass in the hadronic channel at Lep 2 and NLC is discussed. We compare the exact calculation with a ``naive''approach to strong radiative corrections which has been widely used in the literature.
To better understand the nature and internal structure of the exotic states discovered by many collaborations, more information on their electromagnetic properties and their strong and weak interactions with other hadrons is needed. The residue or current coupling constant of these states together with their mass are the main inputs in determinations of such properties. We perform QCD sum rules analyses on the hidden-charm pentaquark states with spin-parities $ J^{P}= \frac{3}{2}^{\pm}$ and $ J^{P}= \frac{5}{2}^{\pm}$ to calculate their residue and mass. In the calculations, we adopt a molecul…
We calculated the complete next-to-leading order(NLO) QCD corrections to the $t\bar t b \bar b$ production process at a $γγ$ collider in the standard model(SM). The calculation of the one-loop QCD correction includes the evaluations of the hexagon and pentagon amplitudes. We studied the NLO QCD corrected total cross section, the distributions of transverse momenta of final top- and bottom-quark states, and the dependence of the cross section on renormalization scale $μ$. It shows that NLO QCD correction generally increases the LO cross section in our chosen parameter space, and the K-factor va…
In this article, we study the ${1\over 2}^+$ doubly heavy baryon states $Ω_{QQ}$ and $Ξ_{QQ}$ by subtracting the contributions from the corresponding ${1\over 2}^-$ doubly heavy baryon states with the QCD sum rules, and make reasonable predictions for their masses. Those doubly heavy baryon states maybe observed at the Tevatron, the LHCb and the PANDA.
We investigate $J/ψ$ decays into octet baryon-antibaryons pairs. The decay amplitudes are computed within the collinear QCD factorisation framework. The subleading amplitude, which describes the decay of longitudinally polarised charmonium, is computed using twist-4 three-quark distribution amplitudes. The obtained results are used for a qualitative analysis of the experimental data. It is found that the polarisation parameter $α_B$ can be described with an accuracy $10-30\%$, which may indicate that the pQCD contribution dominates this observable.
In this article, we study the ${1\over 2}^{\pm}$ and ${3\over 2}^{\pm}$ triply heavy baryon states in an systematic way by subtracting the contributions from the corresponding ${1\over 2}^{\mp}$ and ${3\over 2}^{\mp}$ triply heavy baryon states with the QCD sum rules, and make reasonable predictions for their masses.
A new global QCD analysis of DIS data is presented. The νFe and \barνFe differential cross-section data are included to constrain the strange component of the nucleon sea. As a result we found a hard strangeness at high-x and some evidence for an asymmetry between xs(x) and x\bar{s}(x).
We present a QCD sum rule calculation of the Isgur-Wise form-factor tau_1(v.v') and tau_2(v.v') for the semileptonic decays B->D_1(2420)l\barνand B->D_2^*(2460)l\barνin the framework of heavy quark effective theory. These two universal functions, associated with the matching of the weak currents in QCD onto those in the effective theory, appear at the order 1/m_Q in the heavy quark expansion of meson weak decay form factors.
We calculate the supersymmetric ${\cal O}(α_s)$ QCD corrections to the width of the decay $H^+ \rightarrow \st\bar{\sb}$ within the Minimal Supersymmetric Standard Model. We find that the QCD corrections are significant, but that they do not invalidate our previous conclusionat tree-level on the dominance of the $\st\bar{\sb}$ mode in a wide parameter region.
We propose a model for baryons at finite temperature using AdS/QCD correspondence. In this model, we modify the AdS spacetime into the AdS-Schwarzchild spacetime and consider a couple of bulk spinors in this background. Solving this model, we get an eigenvalue equation for the baryon masses. We then investigate the effects of temperature on the baryon masses numerically, and find an interesting temperature dependence. Our result is consistent with the results from lattice QCD and other phenomenological models.
In this article, we assume that the narrow structure X(4350) is a scalar $\bar{c}c-{D}_s^\ast {\bar {D}}_s^\ast$ mixing state, and study its mass using the QCD sum rules. The numerical result $M_X=(4.37\pm0.15)\,\rm{GeV}$ is in good agreement with the experimental data, the X(4350) may be a scalar $\bar{c}c-{D}_s^\ast {\bar {D}}_s^\ast$ mixing state. Other possibility, such as a scalar (tensor) $cs\bar{c}\bar{s}$ tetraquark state is not excluded.
We construct the heavy baryonic currents by using the Bethe-Salpeter wave functions in the heavy quark limit. We discuss the one-loop renormalization of these heavy baryonic currents as well as their two-point correlators up to the order $1/M_h$. For a special case, we do the QCD sum rule for masses of the doublet (3/2,5/2).
The magnetic moments of heavy $Ξ_{Q}$ baryons containing a single charm or bottom quark are calculated in the framework of light cone QCD sum rules method. A comparison of our results with the predictions of the quark models is presented.
We study effects of charged Higgs boson exchange in $\bar B \to D τ\barν_τ$. The Yukawa couplings of Model II of two-Higgs-doublet model, which has the same Yukawa couplings as MSSM, is considered. We evaluate the decay rate including next-to-leading QCD corrections and estimate uncertainties in the theoretical calculation. Our analysis will contribute to probe an extended Higgs sector at B factory experiments.
Exclusive semileptonic B decays into $D_1$ and $D_2^*$ mesons are investigated including order $Λ_{QCD}/m_{c,b}$ corrections using the heavy quark effective theory. At zero recoil, the $Λ_{QCD}/m_{c,b}$ corrections can be written in terms of the leading Isgur-Wise function for these transitions, $τ$, and known meson mass splittings. We obtain an almost model independent prediction for the shape of the spectrum near zero recoil, including order $Λ_{QCD}/m_{c,b}$ corrections. We determine $τ(1)$ from the measured $B\to D_1\ell\barν$ branching ratio. Implications for B decay sum rules are discuss…
In this article, we take the point of view that the X(1835) be a baryonium state and calculate its mass within the framework of the QCD sum rules approach. The numerical value of the mass of the X(1835) is consistent with the experimental data. There may be some baryonium component in the X(1835) state.
We extend our earlier work on static color singlet correlators in high T QCD (DeTar correlators) to baryonic and gluonic sources, and estimate the corresponding screening masses using the dimensionally reduced theory. We discuss spin and polarization dependence of meson and baryon masses in the $T \rightarrow \infty$ limit, and possible nonperturbative effects at non-asymptotic temperatures.
The $Λ_b \to p$ semileptonic decay is analyzed by using QCD sum rules within the framework of heavy quark effective theory. The Isgur-Wise function of $Λ_b \to p l \barν$ has been calculated. The decay width is given.
In this article, we investigate the mass spectrum of the ground state hidden-charm tetraquark molecular states without strange, with strange and with hidden-strange via the QCD sum rules in a comprehensive way and revisit the assignments of the $X$, $Y$, $Z$ states in the scenario of tetraquark molecular states consistently based on the QCD sum rules.
