Searcharxiv⌕ Search

arXiv subjects

S. Bilmis

Publications and source records attributed to S. Bilmis.

At least 19 recordsLinked to original sources
arXiv2026

Mixing effects in radiative decays of heavy-strange axial-vector mesons within light-cone QCD sum rules

We calculate the radiative decay widths of $D_{s1}(2460)\to D_s\gamma$, $D_{s1}(2536)\to D_s\gamma$, $B_{s1}(5750)\to B_s\gamma$, and $B_{s1}(5830)\to B_s\gamma$ within light-cone QCD sum rules, taking into account the mixing between the $^{1}P_{1}$ and $^{3}P_{1}$ configurations. In the bottom-strange sector, we consider the experimentally established $B_{s1}(5830)$ together with the theoretically expected lower $1^+$ state, denoted $B_{s1}(5750)$. We obtain $\Gamma[D_{s1}(2460)\to D_s\gamma]=45.9^{+10.1}_{-8.5}$ keV, $\Gamma[D_{s1}(2536)\to D_s\gamma]=0.55^{+1.73}_{-0.48}$ keV, $\Gamma[B_{s1}(5750)\to B_s\gamma]=12.0^{+2.9}_{-2.3}$ keV, and $\Gamma[B_{s1}(5830)\to B_s\gamma]=8.9^{+2.4}_{-2.0}$ keV. The $D_{s1}(2460)\to D_s\gamma$ decay width is substantially larger than that of $D_{s1}(2536)\to D_s\gamma$. This difference originates from $^{1}P_{1}$-$^{3}P_{1}$ mixing: the two basis-current contributions interfere constructively for the lower state and destructively for the higher state. In the bottom-strange sector, the two widths are comparable within their uncertainties, although the higher state still exhibits destructive interference. These results show that the radiative decay pattern of strange heavy axial-vector mesons is sensitive to the mixing of the two spin configurations.

hep-ph↗
arXiv2025

Semileptonic $\Lambda_c \to \Lambda \ell \nu_\ell$ Decays in Light-Cone QCD Sum Rules with $\Lambda_c$ Distribution Amplitudes

We study the semileptonic decay of its SU(3) partner, the $\Lambda_c \to \Lambda \ell^+ \nu_\ell$ ($\ell = e, \mu$) transition, within the framework of light-cone QCD sum rules (LCSR) by using the distribution amplitudes of heavy $\Lambda_c$ baryon. The numerical analysis is performed using two different sets of $\Lambda_c$ baryon light-cone distribution amplitudes. The resulting form factors are parametrized by a model-independent $z$-series expansion and used to compute the differential and total decay widths. Our predictions for the branching fractions are in good agreement with the latest BESIII measurements and with lattice-QCD results.

hep-ph↗
arXiv2025

$\Xi_c \to \Xi$ Semileptonic Decays: An LCSR View on the Experiment-Lattice Tension

We present a light-cone QCD sum rule analysis of the semileptonic decays of $\Xi_c$ baryons, focusing on the channels $\Xi_c^0 \to \Xi^- \ell^+ \nu_\ell$, and $\Xi_c^+ \to \Xi^0 \ell^+ \nu_\ell$. The transition form factors are calculated within the light-cone QCD sum rules framework, using the distribution amplitudes of the heavy $\Xi_c$ baryons. The obtained form factors are then used to compute the differential and total decay widths, as well as the branching fractions. Our numerical results for the branching fractions are $\mathcal{B}(\Xi_c^0 \to \Xi^- \ell^+ \nu_\ell) = (3.73 \pm 1.04)~\%$ , $\mathcal{B}(\Xi_c^0 \to \Xi^- \mu^+ \nu_\mu) = (3.59 \pm 1.01)~\%$, $\mathcal{B}(\Xi_c^+ \to \Xi^0 \ell^+ \nu_\ell) = (11.2 \pm 3.25)~\%$, and $\mathcal{B}(\Xi_c^+ \to \Xi^0 \mu^+ \nu_\mu) = (10.8 \pm 3.13)~\%$. These results are in good agreement with recent lattice QCD calculations, while being larger than the current experimental measurements and differing from the predictions of other theoretical approaches.

hep-ph↗
arXiv2024

Mixing angle between $^{3}P_1$ and $^{1}P_1$ states in heavy axial vector mesons within the QCD sum rules framework

In this study, we calculate the mixing angles between the axial-vector mesons $D_{1(s1)} - D_{1(s1)}^\prime$ and $B_{1(s1)} - B_{1(s1)}^\prime$ using the QCD sum rules approach. Our results are $\theta_1 = 28.2 \pm 0.6^\circ$, $\theta_2 = 26.6 \pm 0.6^\circ$, $\theta_3 = 38.6 \pm 0.1^\circ$, and $\theta_4 = 38.5 \pm 0.1^\circ$. These values are in good agreement with the predictions of Heavy Quark Effective Theory, particularly for the mixing angle $\theta = 35.3^\circ$, and are compatible with several existing results in the literature. The predicted mixing angles can be tested through the analysis of semileptonic decays such as $B_c \to B_1 \ell \nu$, $B_c \to B_{s1}^0 \ell \nu$, $B_s \to D_{s1} \ell \nu$, and $B_s \to D_{s1}^\prime \ell \nu$, which can be investigated at experimental facilities such as LHCb and Belle II.

hep-ph↗
arXiv2024

Determination of the multipole moments of the $J^P = 3^-$ mesons via QCD sum rules

The multipole moments of the $J^P = 3^-$ tensor mesons are obtained using light-cone sum rules. Our results are compared with the predictions of the light-cone helicity formalism within the framework of SU(3) flavor symmetry. We observe a good agreement between the two approaches. The obtained multipole moments of tensor mesons provide deeper insights into their properties and better understanding of the strong and electromagnetic decay channels of these mesons.

hep-ph↗
arXiv2024

QCD Sum Rule study of $J^P = 1^\pm$ exotic states with two heavy quarks in the molecular picture

In this study, the spectroscopic parameters of the exotic molecular states composed of mesons containing two heavy quarks (scalar-axial and pseudoscalar-axial meson combinations) are investigated within QCD sum rules. Our findings reveal that the molecular states containing charm quarks do not form bound states, whereas the states with b-quarks can form the exotic molecular states. This observation has significant implications for understanding the structure of these exotic states.

hep-ph↗
arXiv2023

Analysis of the strong decays of SU(3) partners of the $\Omega(2012)$ baryon

We estimate the coupling constants and decay widths of the $SU(3)$ partners of the $\Omega(2012)$ hyperon, as discovered by the BELLE Collaboration, using the light cone sum rules method. Our study includes a comparison of the obtained results for relevant decay widths with those derived within the framework of the flavor $SU(3)$ analysis. We observe a good agreement between the predictions of both approaches. The results we obtain for the branching ratio can provide helpful insights for determining the nature of the $SU(3)$ partners of the $\Omega(2012)$ baryon.

hep-ph↗
arXiv2023

Analysis of the light $J^P = 3^-$ mesons in QCD sum rules

In this study, we investigate the masses and decay constants of the light mesons with $J^P = 3^-$ ( $\rho_3, \omega_3, K_3, \phi_3$) within the QCD sum rules method by taking into account $SU(3)$ violation effects. We state that our predictions on masses of the considered mesons are in good agreement with experimental data within the precision of the model.

hep-ph↗
arXiv2023

The study of weak decays induced by $\frac{1}{2}^+ \to \frac{3}{2}^-$ transition in light-cone sum rules

In this study, we analyzed the weak decays induced by $J^P = \frac{1}{2}^{+} \to \frac{3}{2}^{-} $ transitions within the light-cone sum rules. Specifically, semileptonic decays of the bottom baryons into the P-wave baryons $\Lambda_b \to \Lambda_c(2625) \ell \nu_l$ and $\Xi_b \to \Xi_c(2815) \ell \nu_l$ as well as nonleptonic $\Lambda_b \to \Lambda_c(2625) \pi (\rho)$ and $\Xi_b \to \Xi_c(2815) \pi (\rho)$ decays are investigated. The form factors for the considered transitions are obtained within the sum rules method. With the calculated form factors, the decay widths of the processes are determined. Up to now, only the decay width for $\Lambda_b^0 \to \Lambda_c^+ \mu^- \nu_\mu$ has been measured among the considered decays, and we observe that our finding is quite compatible with the measurement. We also compare our results with the predictions of other approaches.

hep-ph↗
arXiv2022

Looking for heavy axial tensor mesons via their strong decays in light cone QCD

In this study, the strong coupling constants of the unobserved heavy axial tensor mesons to the heavy vector and pseudoscalar $\pi$ and $K$ mesons, $D_2 D^* \pi$, $D_{s2} D^* K$, $B_2 B^* \pi$, $B_{s2} B^* K$ as well as a heavy axial tensor to axial vector and light pseudoscalar $\pi$ and $K$-mesons, $D_2 D_1 \pi$, $D_{s2} D_1 K$, $B_2 B_1 \pi$, $B_{s2} B_1 K$ vertices have been investigated within the light cone QCD sum rules method. Having obtained the strong coupling constants, we estimate the corresponding decay widths that will hopefully be verified in future experiments.

hep-ph↗
arXiv2022

Charmed baryon $\Omega_c^0 \rightarrow \Omega^- l^+ \nu_l$ and $\Omega_c^0 \rightarrow \Omega_c^- \pi^+ (\rho^+)$ decays in light cone sum rules

The semileptonic $\Omega_c^0 \rightarrow \Omega^- l \nu$ and non-leptonic $\Omega_c^0 \to \Omega^- \pi^+$, $\Omega_c^0 \to \Omega^- \rho^+$ decays of charmed $\Omega_c$ baryon are studied within the light cone sum rules. The form factors responsible for $\Omega_c \to \Omega$ transitions are calculated using the distribution amplitudes of $\Omega_c$ baryon. With the obtained form factors, the branching ratios of $\Omega_c^0 \to \Omega^- l^+ \nu_l$, $\Omega_c^0 \rightarrow \Omega^- \pi^+$, and $\Omega_c^0 \rightarrow \Omega^- \rho^+$ decays are estimated. The results are compared with Belle data as well as the findings of the other approaches.

hep-ph↗
arXiv2022

Weak $\Xi_{QQ} \to \Sigma_Q \ell^+ \ell^-$ decays induced by FCNC in QCD

With the discovery of the doubly heavy $\Xi_{cc}$ baryon, comprehensive studies of the properties of the doubly heavy baryons are started. In the present work, we examine the $\Xi_{bb} \to \Sigma_b \ell^+ \ell^-$ and $\Xi_{cc} \to \Sigma_c \ell^+ \ell^-$ decays induced by flavor-changing neutral currents (FCNC) in the framework of the light-cone sum rules. After obtaining the sum rules for the form factors induced by the tensor current, the branching ratios of the relevant transitions are estimated. We found that the branching ratio for the $c \to u$ transition is around five orders smaller than the $b \to d$ transition. Our findings are also compared with other approaches.

hep-ph↗
arXiv2022

Analysis of FCNC $\Xi_{QQ} \to \Lambda_Q l^+ l^-$ decay in light-cone sum rules

The weak decays of doubly heavy $\Xi_{QQ}$ baryon induced by flavor changing $b \to d$ and $ c \to u$ flavor changing neutral current within the light cone sum rules are studied. Using the parallel components of the light cone distribution amplitudes for $\Lambda_Q$ baryon, the sum rules are constructed and analyzed for the corresponding transition form factors. Having the results for the form factors, the corresponding branching ratios for $\Xi_{QQ} \to \Lambda_Q l^+ l^-$ decays are estimated. While the branching ratio due to $b \to d$ transition is around $10^{-9}$, in $c \to u$ transition case, it is found as around $10^{-13}$. Hence, $\Xi_{bb} \to \Lambda_b l^+ l^-$ decay has the potential of being discovered at LHCb. However, $\Xi_{bb} \to \Lambda_b l^+ l^-$ is difficult to be measured due to the extremely small values of obtained branching ratio. Our results on the branching ratio are also compared with the results of the light-front approach.

hep-ph↗
arXiv2022

Properties of doubly heavy baryons in QCD

The study of the properties of doubly heavy baryons represents a promising area in particle physics. It can provide us with information about Cabibbo-Kobayashi-Maskawa (CKM) matrix elements and the low energy dynamics of QCD. They have a very rich phenomenology. The investigation of weak, electromagnetic, and strong decays has vital importance for understanding the dynamics of doubly heavy baryons. The main ingredients of such studies are the spectroscopic parameters, the strong coupling constants, and the transition form factors. For calculations of these quantities, non-perturbative methods are needed. One of these methods is the QCD sum rules. In the present work, we review our studies on the properties of the doubly heavy baryons within the sum rules method, focusing mainly on the mass and strong coupling constants of the doubly heavy baryons. In addition, the radiative decays of doubly heavy baryons are estimated using the vector dominance model. We also make few remarks on the semileptonic decays of the doubly heavy baryons.

hep-ph↗
arXiv2022

Mixing angles between the tetraquark states with two heavy quarks within QCD sum rules

LHCb Collaboration has recently announced the observation of a doubly charmed tetraquark $T_{cc \bar{u} \bar{d}}^+$ state with spin parity $J^P = 1^+$. This exotic state can be explained as a molecular state with small binding energy. According to conventional quark model, both $D^+ D^{0\ast}$ and $(D^0 D^{+\ast})$ multiquark states are expected to have the same mass and flavor in the exact $SU(3)$ symmetry. However, since the quark masses are different, $SU(3) (SU(2))$ symmetry is violated, hence, the mass and flavor eigenstates do not coincide. The mass eigenstates can be represented as a linear combination of the flavor eigenstates, which is characterized by the mixing angle $\theta$. In the present work, the possible mixing angles between the $T_{cc}$ states are calculated. Moreover, the analysis are extended for all the possible tetraquarks scenarios with two heavy and two light quarks within the molecular picture although those states have not been observed yet. Our prediction on mixing angle between doubly charmed tetraquark states shows that $SU(3)$ symmetry breaking is around $7\%$ maximally.

hep-ph↗
arXiv2021

Determination of the spectroscopic parameters of beauty-partners of $T_{cc}$ from QCD

Motivated by the recent discovery of a new tetra-quark $T_{cc}^+$ state with two charm quarks and two light quarks by LHCb collaboration, we calculate the spectroscopic parameters, namely, the mass and residues of beauty partners of $T_{cc}^+$ within QCD sum rules by using hadronic molecular $BB^*$ picture. The obtained results are compared with the predictions of different approaches in the literature.

hep-ph↗