arXiv subjects

S. S. Agaev

Publications and source records attributed to S. S. Agaev.

At least 73 records · Page 4Linked to original sources

arXiv2019

The nonet of the light scalar tetraquarks: the mesons $a_0(980)$ and $K_{0}^{\ast }(800)$

The spectroscopic parameters and partial decay widths of the light mesons $ a_0(980) $ and $K_{0}^{\ast}(800)$ are calculated by treating them as scalar diquark-antidiquark states. The masses and couplings of the mesons are found in the framework of QCD two-point sum rule approach. The widths of the decay channels $a_0(980) \to ηπ$ and $a_0(980) \to K \bar{K}$, and $ K_{0}^{\ast}(800) \to K^{+} π^{-}$ and $K_{0}^{\ast}(800) \to K^{0} π^{0} $ are evaluated using QCD sum rules on the light-cone and technical tools of the soft meson approximation. Our results for the mass of the mesons $m_{a_0}=991^{+29}_{-27} \ \mathrm{MeV}$ and $m_{K^{ \ast}}=767^{+38}_{-29} \ \mathrm{MeV}$, as well as their total width $Γ_{\mathrm{a_0}}=62.01\pm 14.37\ \mathrm{MeV}$ and $Γ_{\mathrm{ K_0^{\ast}}}=401.1\pm 87.1\ \mathrm{MeV}$ are compared with last experimental data.

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arXiv2018

The doubly charmed pseudoscalar tetraquarks $T_{cc;\bar{s} \bar{s}}^{++}$ and $T_{cc;\bar{d} \bar{s}}^{++}$

The mass and coupling of the doubly charmed $J^P=0^{-}$ diquark-antidiquark states $T_{cc;\bar{s} \bar{s}}^{++}$ and $T_{cc;\bar{d} \bar{s}}^{++}$ that bear two units of the electric charge are calculated by means of QCD two-point sum rule method. Computations are carried out by taking into account vacuum condensates up to and including terms of tenth dimension. The dominant $S$-wave decays of these tetraquarks to a pair of conventional $ D_{s}^{+}D_{s0}^{\ast +}(2317)$ and $D^{+}D_{s0}^{\ast +}(2317)$ mesons are explored using QCD three-point sum rule approach, and their widths are found. The obtained results $m_{T}=(4390~\pm 150)~\mathrm{MeV}$ and $Γ=(302 \pm 113~\mathrm{MeV}$) for the mass and width of the state $T_{cc;\bar{ s} \bar{s}}^{++}$, as well as spectroscopic parameters $\widetilde{m} _{T}=(4265\pm 140)~\mathrm{MeV}$ and $\widetilde{Γ}=(171~\pm 52)~ \mathrm{MeV}$ of the tetraquark $T_{cc;\bar{d} \bar{s}}^{++}$ may be useful in experimental studies of exotic resonances.

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arXiv2018

Resonance $Y(4660)$ as a vector tetraquark and its strong decay channels

The spectroscopic parameters and partial widths of the strong decay channels of the vector meson $Y(4660)$ are calculated by treating it as a bound state of a diquark and antidiquark. The mass and coupling of the $J^{PC}=1^{--}$ tetraquark $Y(4660) $ are evaluated in the context of the two-point sum rule method by taking into account the quark, gluon and mixed condensates up to dimension 10. The widths of the $Y(4660)$ resonance's strong $S$-wave decays to $J/ψf_{0}(980)$ and $ψ(2S) f_{0}(980)$ as well as to $ J/ψf_{0}(500)$ and $ψ(2S) f_{0}(500)$ final states are computed. To this end, strong couplings in the relevant vertices are extracted from the QCD sum rule on the light cone supplemented by the technical methods of the soft approximation. The obtained result for the mass of the resonance $ m_Y=4677^{+71}_{-63}\ \mathrm{MeV}$ and the prediction for its total width $ Γ_{Y}= (64.8 \pm 10.8)\ \mathrm{MeV}$ is in nice agreement with the experimental information.

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arXiv2018

Probing an axial-vector tetraquark $Z_s$ via its semileptonic decay $Z_s \to X(4274)\overline{l} ν_l$

The semileptonic decays of the open charm-bottom axial-vector tetraquark $ Z_{s}=[cs][\overline{b}\overline{s}]$ to $X(4274)\overline{l} ν_l$, $l=e, μ, τ$ are explored by means of the QCD three-point sum rule method. Both $Z_{s}$ and $X(4274)=[cs][\overline{c}\overline{s}]$ are treated as color sextet diquark-antidiquark states. The full width of the decays $Z_s \to X(4274)\overline{l} ν_l$ is found. Obtained predictions for $ Γ(Z_s \to X(4274)\overline{l} ν_l)$ demonstrate that, as in the case of the conventional hadrons, the semileptonic transitions form a very small part of its full width.

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arXiv2018

The strong decays of the light scalar mesons $f_0(500)$ and $f_0(980)$

The partial width of the decay channels $f_0(500) \to ππ$, $f_0(980) \to ππ$ and $f_0(980) \to K \bar K$ are calculated using QCD light-cone sum rules method and a technique of the soft meson approximation. The scalar particles are treated as mixtures of the heavy $|H\rangle =([su][\bar s \bar u]+[sd][\bar s \bar d])/\sqrt 2$ and light $|L\rangle =[ud][\bar u \bar d]$ scalar diquark-antidiquark components. Obtained results for the full width of the $f_0(500)$ meson $Γ_{\mathrm{th}.}=434.7\pm 72.3~\mathrm{MeV}$ and for the $f_0(980)$ meson $Γ_{\mathrm{th.}}=42.12\pm 6.70~\mathrm{MeV }$ are compared with the world averages for these parameters, and a reasonable agreement between them is found.

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arXiv2018

The structure, mixing angle, mass and couplings of the light scalar $f_0(500)$ and $f_0(980)$ mesons

The mixing angle, mass and couplings of the light scalar mesons $f_0(500)$ and $f_0(980)$ are calculated in the framework of QCD two-point sum rule approach by assuming that they are tetraquarks with diquark-antidiquark structures. The mesons are treated as mixtures of the heavy $|H\rangle =([su][\bar s \bar u]+[sd][\bar s \bar d])/\sqrt 2$ and light $|L\rangle =[ud][\bar u \bar d]$ scalar diquark-antidiquark components. We extract from corresponding sum rules the mixing angles $φ_H$ and $φ_L$ of these states and evaluate the masses and couplings of the particles $ f_0(500) $ and $f_0(980)$.

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arXiv2018

The new $a_1(1420)$ state: structure, mass and width

The structure, spectroscopic parameters and width of the resonance with quantum numbers $J^{PC}=1^{++}$ discovered by the COMPASS Collaboration and classified as the $a_1(1420)$ meson are examined in the context of QCD sum rule method. In the calculations the axial-vector meson $a_1(1420)$ is treated as a four-quark state with the diquark-antidiquark structure. The mass and current coupling of $a_1(1420)$ are evaluated using QCD two-point sum rule approach. Its observed decay mode $a_1(1420) \to f_0(980)π$, and kinematically allowed ones, namely $a_1 \to K^{\ast \pm}K^{\mp}$, $a_1 \to K^{\ast 0} \bar{K}^{0}$ and $a_1 \to \bar {K}^{\ast 0} K^{0}$ channels are studied employing QCD sum rules on the light-cone. Our prediction for the mass of the $a_1(1420)$ state $m_{a_{1}}=1416_{-79}^{+81}\ \mathrm{MeV}$ is in excellent agreement with the experimental result. Width of this state $ Γ=145.52 \pm 20.79 \mathrm{MeV}$ within theoretical and experimental errors is also in accord with the COMPASS data.

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arXiv2018

Testing the doubly charged charm-strange tetraquarks

The spectroscopic parameters and decay channels of the doubly charged scalar, pseudoscalar and axial-vector charm-strange tetraquarks $Z_{ \overline{c}s}=[sd][\overline u \overline c]$ are explored within framework of the QCD sum rule. The masses and current couplings of these diquark-antidiquark states are calculated by means of two-point correlation functions and taking into account the vacuum condensates up to eight dimensions. To compute the strong couplings of $Z_{\overline{c}s}$ states with $D,\ D_{s},\ D^{\ast},\ D_{s}^{\ast},\ D_{s1}(2460),\ D_{s0}^{\ast}(2317),\ π$ and $K$ mesons we use QCD light-cone sum rules and evaluate width of their $S$- and $P$-wave decays to a pair of negatively charged conventional mesons: For the scalar state $Z_{\overline{c}s}\to D_s π,\ DK, \ D_{s1}(2460)π$, for the pseudoscalar state $Z_{\overline{c}s} \to D_{s}^{\ast}π,\ D^{\ast}K, \ D_{s0}^{\ast}(2317)π,$ and for the axial-vector state $Z_{\overline{c}s} \to D_{s}^{\ast}π,\ D^{\ast}K,\ D_{s1}(2460)π$ decays are investigated. Obtained predictions for the spectroscopic parameters and decay widths of the $Z_{\overline{c}s}$ tetraquarks may be useful for experimental investigations of the doubly charged exotic hadrons.

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arXiv2017

Spectroscopic parameters and decays of the resonance $Z_b(10610)$

The resonance $Z_b(10610)$ is investigated as the diquark-antidiquark $ Z_b=[bu][\overline b \overline d]$ state with spin-parities $J^{PC}=1^{+-}$. The mass and current coupling of the resonance $Z_b(10610)$ are evaluated using QCD two-point sum rule and taking into account the vacuum condensates up to ten dimensions. We study the vertices $ Z_bΥ(nS)π (n=1,2,3)$ by applying the QCD light-cone sum rule to compute the corresponding strong couplings $g_{Z_bΥ(nS)π}$ and widths of the decays $Z_b \to Υ(nS)π$. We explore also the vertices $Z_b h_{b}(mP)π (m=1,2)$ and calculate the couplings $g_{Z_b h_{b}(mP)π}$ and width of the decay channels $Z_b \to h_{b}(mP)π$. To this end, we calculate the mass and decay constants of the $h_b(1P)$ and $h_b(2P) $ mesons. The results obtained are compared with experimental data of the Belle Collaboration.

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arXiv2017

Decay widths of the excited $Ω_b$ baryons

The LHCb Collaboration recently observed five narrow $Ω_c^{0}$ resonances, and measured their masses and widths through the decays $ Ω_c^{0} \to Ξ_c^{+}K^{-}$. Motivated by this discovery, and also by the fact that the ground-state bottom baryon $Ω_b^{-}$ with spin-1/2 was already found experimentally, we perform theoretical investigation of the spin-1/2 and spin-3/2, $Ω_b$, baryons by calculating decay width of their first orbitally and radially excited states to $Ξ_b^{0} K^{-}$. For this purpose, we employ QCD sum rule method on the light-cone by including into analysis the $K$ meson distribution amplitudes up to twist-4. Obtained analytical expressions are utilized to extract parameters of these decay processes which may be useful for forthcoming experimental studies of bottom baryons.

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arXiv2017

Treating $Z_c(3900)$ and $Z(4430)$ as the ground-state and first radially excited tetraquarks

Exploration of the resonances $Z_c(3900)$ and $Z(4430)$ are performed by assuming that they are ground-state and first radial excitation of the same tetraquark with $J^{P}=1^{+}$. The mass and current coupling of the $ Z_c(3900)$ and $Z(4430)$ states are calculated using QCD two-point sum rule method by taking into account vacuum condensates up to eight dimensions. We investigate the vertices $Z_cM_hM_l$ and $ZM_hM_l$, with $M_h$ and $M_l $ being the heavy and light mesons, and evaluate the strong couplings $ g_{Z_cM_hM_l}$ and $g_{ZM_hM_l}$ using QCD sum rule on the light cone. The extracted couplings allow us to find the partial width of the decays $ Z_c(3900) \to J/ψπ; \,ψ^{\prime} π;\, η_c ρ$ and $Z(4430) \to ψ^{\prime} π;\, J/ψπ;\, η_c^{\prime}ρ;\, η_cρ$, which may help in comprehensive investigation of these resonances. We compare width of the decays of $Z_c(3900)$ and $Z(4430)$ resonances with available experimental data as well as existing theoretical predictions.

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arXiv2017

Exploring the resonances $X(4140)$ and $X(4274)$ through their decay channels

Investigation of the resonances $X(4140)$ and $X(4274)$, which were recently confirmed by the LHCb Collaboration [1], is carried out by treating them as the color triplet and sextet $[cs][\bar{c}\bar {s}]$ diquark-antidiquark states with the spin-parity $J^{P}=1^{+}$, respectively. We calculate the masses and meson-current couplings of these tetraquarks in the context of QCD two-point sum rule method by taking into account the quark, gluon and mixed vacuum condensates up to eight dimensions. We also study the vertices $X(4140)J/ψϕ$ and $X(4274)J/ψϕ$, and evaluate corresponding strong couplings $g_{X(4140)J/ψϕ}$ and $ g_{X(4274)J/ψϕ}$ by means of QCD light-cone sum rule method, and a technique of the soft-meson approximation. In turn, these couplings contain a required information to determine the width of the $X(4140)\to J/ψϕ$ and $X(4274) \to J/ψϕ$ decay channels. We compare our results for the masses and decay widths of the $X(4140)$ and $X(4274)$ resonances with the LHCb data, and alternative theoretical predictions.

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arXiv2017

Open charm-bottom axial-vector tetraquarks and their properties

The charged axial-vector $J^{P}=1^{+}$ tetraquarks $Z_{q}=[cq][\bar {b} \bar q ]$ and $Z_{s}=[cs][\bar {b} \bar s]$ with the open charm-bottom contents are studied in the diquark-antidiquark model. The masses and meson-current couplings of these states are calculated by employing QCD two-point sum rule approach, where the quark, gluon and mixed condensates up to eight dimensions are taken into account. These parameters of the tetraquark states $ Z_{q}$ and $Z_{s}$ are used to analyze the vertices $Z_q B_c ρ$ and $Z_s B_c ϕ$ to determine the strong $g_{Z_qB_c ρ}$ and $g_{Z_sB_c ϕ}$ couplings. For these purposes, QCD light-cone sum rule method and its soft-meson approximation are utilized. The couplings $g_{Z_qB_c ρ}$ and $ g_{Z_sB_c ϕ}$, extracted from this analysis, are applied for evaluating of the strong $Z_q \to B_c ρ$ and $Z_s \to B_c ϕ$ decays' widths, which are essential results of the present investigation. Our predictions for the masses of the $Z_{q}$ and $Z_{s}$ states are confronted with similar results available in the literature.

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arXiv2017

Interpretation of the new $Ω_c^{0}$ states via their mass and width

The mass and pole residue of the ground and first radially excited $ Ω_c^{0}$ states with spin-parities $J^{P}=1/2^{+},\,3/2^{+}$, as well as P-wave $Ω_c^{0}$ with $J^{P}=1/2^{-},\,3/2^{-}$ are calculated by means of the two-point QCD sum rules. The strong decays of $Ω_c^{0}$ baryons are also studied and width of these decay channels are computed. The relevant computations are performed in the context of the full QCD sum rules on the light-cone. Obtained results for the masses and widths are confronted with recent experimental data of LHCb Collaboration, which allow us to interpret $Ω_c(3000)^{0}$, $Ω_c(3050)^{0}$, and $ Ω_c(3119)^{0} $ as the excited $css$ baryons with the quantum numbers $ (1P,\,1/2^{-})$, $(1P,\,3/2^{-})$, and $(2S,\,3/2^{+})$, respectively. The $ (2S,\,1/2^{+})$ state can be assigned either to $Ω_c(3066)^{0}$ state or $Ω_c(3090)^{0}$ excited baryon.

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arXiv2017

On the nature of the newly discovered $Ω_c^{0}$ states

The masses and residues of the radially excited heavy $Ω_c^{0}$ and $ Ω_b^{-}$ baryons with spin-parity $J^{P}=\frac{1}{2}^{+}$ and $J^{P}= \frac{3}{2}^{+}$ are calculated by means of QCD two-point sum rule method using the general form of their interpolating currents. In calculations the quark, gluon and mixed vacuum condensates up to ten dimensions are taken into account. In $Ω_c^{0}$ channel a comparison is made with the narrow excited states recently observed by the LHCb Collaboration.

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arXiv2017

Application of the QCD light cone sum rule to tetraquarks: the strong vertices $X_bX_bρ$ and $X_cX_cρ$

The full version of QCD light-cone sum rule method is applied to tetraquarks containing a single heavy $b$ or $c$ quark. To this end, investigations of the strong vertices $X_{b}X_{b}ρ$ and $X_{c}X_{c}ρ$ are performed, where $X_b=[su][\bar b\bar d]$ and $X_c=[su][\bar c\bar d]$ are the exotic states built of four quarks of different flavors. The strong coupling constants $G_{X_{b}X_{b}ρ}$ and $G_{X_{c}X_{c}ρ}$ corresponding to these vertices are found using the $ρ$-meson leading and higher-twist distribution amplitudes. In the calculations $X_{b}$ and $X_{c}$ are treated as scalar bound states of a diquark and antidiquark.

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arXiv2017

Open charm-bottom scalar tetraquarks and their strong decays

The mass and meson-current coupling of the diquark-antidiquark states with the quantum numbers $J^{P}=0^{+}$ and quark contents $Z_{q}=[cq][\bar {b} \bar q ]$ and $Z_{s}=[cs][\bar {b} \bar s]$ are calculated using two-point QCD sum rule approach. In calculations the quark, gluon and mixing condensates up to eight dimensions are taken into account. The parameters of the scalar tetraquarks extracted from this analysis are employed to explore the strong vertices $Z_q B_c π$, $Z_q B_c η$ and $Z_s B_c η$ and compute the couplings $g_{Z_qB_c π}$, $g_{Z_qB_c η}$ and $g_{Z_sB_c η}$. The strong couplings are obtained within the soft-meson approximation of QCD light-cone sum rule method: they form, alongside with other parameters, the basis for evaluating the widths of $Z_q \to B_c π$, $% Z_q \to B_c η$ and $Z_s \to B_c η$ decays. Obtained in this work results for the mass of the tetraquarks $Z_{q}$ and $Z_{s}$ are compared with available predictions presented in the literature.

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arXiv2017

Resonance $X(5568)$ as an exotic axial-vector state

The mass and meson-current coupling constant of the resonance $X(5568)$, as well as the width of the decay $X(5568)\to B_s^{\ast}π$ are calculated by modeling the exotic $X(5568)$ resonance as a diquark-antidiquark state $% X_b=[su][bd]$ with quantum numbers $J^{P}=1^{+}$. The calculations are made employing QCD two-point sum rule method, where the quark, gluon and mixed vacuum condensates up to dimension eight are taken into account. The sum rule approach on the light-cone in its soft-meson approximation is used to explore the vertex $X_bB_{s}^{\ast}π$ and extract the strong coupling $% g_{X_bB_{s}^{\ast}π}$, which is a necessary ingredient to find the width of the $X_b \to B_s^{\ast}π^{+}$ decay process. The obtained predictions are compared with the experimental data of the D0 Collaboration, and results of other theoretical works.

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