Search

The semileptonic $B_{(s)} \rightarrow T(J^P=2^-)l^+l^-$ decays induced by flavor changing neural currents are investigated within the light cone QCD sum rule method. We apply the $B$ meson distribution amplitudes up to twist-4 and calculate the relevant form factors of the $B_{(s)} \rightarrow T$ transitions, where $T=K_2,~a_2,~f_2,~\phi_2$ with $J^P=2^-$. The obtained results of the form factors then adopted in the calculations of the corresponding widths. The present results can be used in future experiments for studying the properties of $J^P=2^-$ tensor mesons.

In this study, we calculate the mixing angles between the axial-vector mesons $^{3}P_1$ and $^{1}P_1$, specifically $D_{1(s1)} - D_{1(s1)}'$ and $B_{1(s1)} - B_{1(s1)}'$ within the framework of QCD sum rules. Our results for the mixing angles are smaller than those predicted by the Bethe-Salpeter, relativistic and non-relativistic quark models. These angles can be measured by analyzing various decay channels at experiments conducted at BELLE II, and LHCb.

The possibility of electric field control of magnetocaloric effect through quasi-isostatic compression as a result of the converse piezoelectric effect was demonstrated on cylindrical type magnetoelectric composite MnAs/PZT. It was shown that an electric voltage of 100 V corresponding to an electric field of E ~0.3 kV/mm applied to the walls of the piezoelectric component PZT of the MnAs/PZT composite contributes to an increase in the maximum adiabatic temperature change by 0.2 K in the temperature range of the magnetostructural phase transition of MnAs ~317 K at magnetic field change of 1.8 T. Calculations using the finite element method have shown that an electric field voltage of 100 V is capable of creating a quasi-isostatic mechanical stress in the region inside a cylindrical PZT tube of ~3 MPa. Moreover, in the region of weak pressures up to 10 MPa, the contribution to the MCE from piezo compression linearly depends on the electrical voltage that can be used for control the MCE

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.

The ability to control by physical properties of the thermoresponsive polymer of PNIPAM by magnetocaloric effect was demonstrated by in-situ experiments on PNIPAM/FeRh smart composite. The concept of drug release loaded in smart composite by applying of 3 T magnetic field was demonstrated using an example of doxorubicin. Released results of the magnetic field applying the drug were detected using IV-VIS and Raman spectroscopy. In vitro, studies have demonstrated a high degree of PNIPAM/FeRh scaffold biocompatibility for primary mouse embryonic fibroblasts (PMEF) cell culture. PMEFs effectively ad-hered to the PNIPAM/FeRh scaffold surface and showed high metabolic and proliferative activity for 72 h after seeding., Comment: 8 pages, 12 figures

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., Comment: To be published in Chinese Physics C

It is shown that the phase shift between an applied weak alternating magnetic field and the magnetocaloric response signal of the magnetic material is drastically sensitive to the order of phase transition. Namely, at the second-order phase transition, the phase shift does not depend on the magnetic field magnitude, while in the first-order phase transition this one depends significantly on the field strength. We have shown that this effect follows from the general critical dynamics theory.

The upper limit of the branching ratio of the rare $\Xi_b^-\rightarrow \Xi^- \gamma$ decay is obtained as $BR(\Xi_b^-\rightarrow \Xi^- \gamma)<1.3\times10^{-4}$ by the LHCb. In the present work we study this decay within the light cone QCD sum rules employing the $\Xi_b$ distribution amplitudes. At first stage, the form factors entering the $\Xi_b^-\rightarrow \Xi^- \gamma$ decay are obtained. Next, using the results for the form factors the corresponding branching ratio for this decay is estimated to be $BR(\Xi_b^-\rightarrow \Xi^- \gamma)=(4.8\pm 1.3)\times 10^{-5}$. This value lies below the upper limit established by the LHCb collaboration. Our finding for the branching ratio is also compared with the results of the other theoretical approaches existing in the literature., Comment: 10 pages, 3 figures

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.

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., Comment: Typos are corrected in this new version

The spin-$\nicefrac{3}{2}$ to spin-$\nicefrac{1}{2}$ doubly heavy baryon transition magnetic dipole $G_M$ and electric quadrupole $G_E$ formfactors are calculated in the framework of light cone sum rules method. Moreover, the decay widths of corresponding radiative transitions are estimated. Obtained results of magnetic dipole moments $G_M$ and decay widths are compared with the results present in the literature.

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.

Abelian dark sector scenarios embedded into the two-Higgs doublet model are scrutinized within the Coherent Elastic Neutrino-Nucleus Scattering (CE$\nu$NS) experiment, which was first measured by the COHERENT Collaboration in 2017 with an ongoing effort to improve it since then and recently released data for the CsI target in 2022. In the theoretical framework, it is assumed that there is a $U(1)$ gauge group in the dark sector with a non-zero kinetic mixing with the hypercharge field. The COHERENT data for the targets CsI and liquid argon (LAr) are treated in both single and multi bin bases to constrain the multi dimensional parameter space, spanned by the dark gauge coupling, kinetic mixing parameter and the dark photon mass, of totally seven different representative scenarios which are also compared and contrasted among each other to find out about the most sensitive one to the data. The effect of refined quenching factor is also addressed., Comment: 29 pages, 3 tables, 7 figures (one figure added), new references included, discussion extended, matching the journal version

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.

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.

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.

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., Comment: Figures for the variation of the form factors with respect to the Borel mass parameter are added. And some typos are corrected

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., Comment: Review, 31 pages

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.

Form factors of the weak $\Xi_c \to \Xi(\Lambda)$ transitions are calculated within the light cone QCD sum rules. The pollutions coming from the contribution of the negative parity $\Xi_c^*$ baryon is eliminated by considering the combinations of sum rules corresponding to the different Lorentz structures. Having obtained the form factors, the branching ratios of the $\Xi_c \to \Xi (\Lambda) \ell \nu$ decays are also calculated, and our predictions are compared with the results of other approaches as well as the measurements done by BELLE and ALICE Collaborations.

We estimate the strong coupling constants of charmed and bottom mesons $ D_{(s)}^* $, $ D_{(s)1} $, $ B_{(s)}^* $, and $ B_{(s)1} $ with light vector mesons $ \rho $, $ \omega $, $ K^* $, and $ \phi $ within the framework of light-cone QCD sum rules. We compare our estimations to the ones predicted by other approaches., Comment: 18 pages, 2 figures v2: 19 pages, 2 figures, added more references

The strong coupling constants of spin-3/2 to spin-1/2 doubly heavy baryon transitions with light vector mesons are estimated within the light-cone QCD sum rules method. Moreover, using the vector-meson dominance ans\"atz, the widths of radiative decays $B_{QQ}^* \to B_{QQ} \gamma$ are calculated. The results for the said decay widths are compared to the predictions of other approaches., Comment: 16 pages, 6 figures, 7 tables

Magnetic dipole moment form factor, $G_M^{(2)}(Q^2)$, describing the radial excitation of decuplet baryons to octet baryons electromagnetic transitions as well as the ratios, $R_{SM} = -\frac{1}{4 m_2^2} \sqrt{4 m_2^2 Q^2 + (m_2^2 - Q^2 -m_1^2)^2} \frac{G_C^{(2)}(Q^2)}{G_M^{(2)}(Q^2)}$ and $R_{EM} = -\frac{G_E^{(2)}(Q^2)}{G_M^{(2)}(Q^2)}$ are calculated in the framework of light-cone sum rules. We also estimate the degree of the violation of U-spin symmetry. The obtained results for the multipole form factors can be useful in searching the properties of radially excited baryon states., Comment: 21 pages, 7 figures

In this paper, we analyze the doubly heavy spin-3/2--spin-1/2 baryons and light meson vertices within the method of light-cone QCD sum rules. These vertices are parametrized in terms of one (three) coupling constant(s) for the pseudoscalar (vector) mesons. The said coupling constants are calculated for all possible transitions. The results presented here can serve to be useful information in experimental as well as theoretical studies of the properties of doubly heavy baryons., Comment: 27 pages, 8 figures, 4 tables

Taking into account only the quark part of the energy-momentum tensor, the gravitational form-factors of the $ \pi $ and $ K $ mesons are calculated within the light-cone sum rules method using the distribution amplitudes of these pseudoscalar mesons. The $ Q^2 $-dependence of the relevant form-factors are obtained. Moreover, the mean square mass radii of $ \pi $ and $ K $ mesons are calculated and we find that $ \sqrt{\langle r_{\pi}^2 \rangle} = 0.31 {\rm\ fm} $ and $ \sqrt{\langle r_{K}^2 \rangle} = 0.24 {\rm\ fm} $, respectively. We compare our results for gravitational form-factors with the existing literature results. We obtain that our results on $ \sqrt{\langle r_\pi^2 \rangle} $ are in good agreement with the predictions of NJL model, AdS/QCD model, and other models as well as with the existing experimental data., Comment: 11 pages, 4 figures

Using the most general form of the interpolating current for baryons, the strong electric and magnetic coupling constants of light vector mesons $ \rho $ and $ K^* $ with doubly heavy baryons are computed within the light-cone sum rules. We consider 2- and 3-particle distribution amplitudes of the aforementioned vector mesons. The obtained results can be useful in the analysis of experimental data on the properties of doubly heavy baryons conducted at LHC., Comment: 27 pages, 6 fgures