We present a study on the impact of scalar leptoquarks on the semileptonic decays of Λb, Σb, and Ξb. To this end, we calculate the differential branching ratio and lepton forward-backward asymmetry ...defining the processes Λb→Λl+l-, Σb→Σl+l-, and Ξb→Ξl+l-, with l being μ or τ, using the form factors calculated via light cone QCD in full theory. In calculations, the errors of form factors are taken into account. We compare the results obtained in leptoquark model with those of the standard model as well as the existing lattice QCD predictions and experimental data.
A
bstract
We work out the semileptonic Λ
b
→ Λℓ
+
ℓ
−
transition in standard as well as different supersymmetric models. In particular, considering the parametrization of the matrix elements entered ...the low energy effective Hamiltonian in terms of form factors in full QCD, we calculate the amplitude and differential decay rate responsible for this decay channel in supersymmetric models. We then use the form factors calculated via light cone QCD sum rules in full theory to analyze the differential branching ratio and lepton forward-backward asymmetry of this decay channel in different supersymmetric models and compare the obtained results with those of the standard model. We also discuss how the results of different supersymmetric models deviate from the standard model predictions and which SUSY scenarios are favored.
Using transition form factors calculated via light cone QCD sum rules in full theory, we comparatively analyze the rare radiative capital sigma sub(b) arrow right capital sigma sub( gamma ) decay in ...the standard model (SM) and models with one or two universal extra dimensions, such as beyond the SM scenarios. We estimate the total decay width and branching ratio associated with this decay channel in the SM and compare the obtained results with those of scenarios with one or two universal extra dimensions. We discuss how the results of universal extra dimensional models approach the SM predictions when the compactification factor of extra dimension is increased.
A
bstract
We obtain a lower limit on the compactification scale of extra dimension via comparison of the branching ratio in the baryonic Λ
b
→ Λ
μ
+
μ
−
decay channel recently measured by CDF ...collaboration and our previous theoretical study. We also use the newly available form factors calculated via light cone QCD sum rules in full theory to analyze the flavour changing neutral current process of the Σ
b
→ Σ
ℓ
+
ℓ
−
in universal extra dimension scenario in the presence of a single extra compact dimension. We calculate various physical quantities like branching ratio, forward-backward asymmetry, baryon polarizations and double lepton polarization asymmetries defining the decay channel under consideration. We also compare the obtained predictions with those of the standard model.
Experimental data on , , and , provided by different collaborations, show sizable deviations from the standard model predictions. To describe these anomalies, many new physics scenarios have been ...proposed. One of them is the leptoquark model, which introduces the simultaneous coupling of vector and scalar leptoquarks to quarks and leptons. To look for similar possible anomalies in the baryonic sector, we investigate the effects of a vector leptoquark on various physical quantities related to the tree-level decays ( ), which proceed via transitions at the quark level. We calculate the differential branching ratio, forward-backward asymmetry, and longitudinal polarizations of leptons and baryons at the and lepton channels in the leptoquark model and compare their behavior to the predictions of the SM in terms of . In the calculations, we use the form factors calculated in full QCD as the main input and account for all errors coming from the form factors and model parameters. We observe that at the channel, the fit solution to data related to the leptoquark model sweeps some regions out of the SM band; nevertheless, the fit has a considerable intersection with the SM predictions. The type solution gives roughly the same results as the SM on . At the channel, the leptoquark model gives results that are consistent with the SM predictions and existing experimental data on the behavior of with respect to . Concerning the behavior of the , the two types of fits for and the predictions at the channel in the leptoquark model give exactly the same results as the SM. We also investigate the behavior of the parameter with respect to and the value of in both the vector leptoquark and SM models. Both fit solutions lead to results that deviate considerably from the SM predictions for and . Future experimental data on and , made available by measurements of the channel, will be particularly helpful. Any experimental deviations from the SM predictions in this channel would emphasize the importance of tree-level hadronic weak transitions as good probes of new physics effects beyond the SM.
Experimental data on $ R(D^{(*)}) $, $ R(K^{(*)}) $ and $ R(J/\psi) $,
provided by different collaborations, show sizable deviations from the SM
predictions. To describe these anomalies many new ...physics scenarios have been
proposed. One of them is leptoquark model with introducing the vector and
scalar leptoquarks coupling simultaneously to the quarks and leptons. To look
for similar possible anomalies in baryonic sector, we investigate the effects
of a vector leptoquark $U_3 (3,3, \frac{2}{3})$ on various physical quantities
related to the tree-level $ \Lambda_b \rightarrow \Lambda_c \ell ~
\overline{\nu}_\ell$ decays ($ \ell=\mu, ~\tau $), which proceed via $ b
\rightarrow c~\ell ~ \overline{\nu}_\ell$ transitions at quark level. We
calculate the differential branching ratio, forward-backward asymmetry and
longitudinal polarizations of lepton and $\Lambda_{c}$ baryon at $ \mu $ and $
\tau $ lepton channels in leptoquark model and compare their behavior with
respect to $ q^2 $ with the predictions of the standard model (SM). In the
calculations we use the form factors calculated in full QCD as the main inputs
and take into account all the errors coming from the form factors and model
parameters. It is observed that ...
Experimental data on \( R(D^{(*)}) \), \( R(K^{(*)}) \) and \( R(J/\psi) \), provided by different collaborations, show sizable deviations from the SM predictions. To describe these anomalies many ...new physics scenarios have been proposed. One of them is leptoquark model with introducing the vector and scalar leptoquarks coupling simultaneously to the quarks and leptons. To look for similar possible anomalies in baryonic sector, we investigate the effects of a vector leptoquark \(U_3 (3,3, \frac{2}{3})\) on various physical quantities related to the tree-level \( \Lambda_b \rightarrow \Lambda_c \ell ~ \overline{\nu}_\ell\) decays (\( \ell=\mu, ~\tau \)), which proceed via \( b \rightarrow c~\ell ~ \overline{\nu}_\ell\) transitions at quark level. We calculate the differential branching ratio, forward-backward asymmetry and longitudinal polarizations of lepton and \(\Lambda_{c}\) baryon at \( \mu \) and \( \tau \) lepton channels in leptoquark model and compare their behavior with respect to \( q^2 \) with the predictions of the standard model (SM). In the calculations we use the form factors calculated in full QCD as the main inputs and take into account all the errors coming from the form factors and model parameters. It is observed that ...
Radiative decay in SM and BSM Azizi, K; Kartal, S; Olgun, A T ...
Journal of physics. G, Nuclear and particle physics,
08/2014, Letnik:
41, Številka:
9
Journal Article
Recenzirano
Using transition form factors calculated via light cone QCD sum rules in full theory, we comparatively analyze the rare radiative decay in the standard model (SM) and models with one or two universal ...extra dimensions, such as beyond the SM scenarios. We estimate the total decay width and branching ratio associated with this decay channel in the SM and compare the obtained results with those of scenarios with one or two universal extra dimensions. We discuss how the results of universal extra dimensional models approach the SM predictions when the compactification factor of extra dimension is increased.
We present a study on the impact of scalar leptoquarks on the semileptonic decays of \( \Lambda_b\), \(\Sigma_b \) and \(\Xi_b \). To this end, we calculate the differential branching ratio and ...lepton forward-backward asymmetry defining the processes \( \Lambda_b \rightarrow \Lambda \ell^+ \ell^-\), \(\Sigma_b \rightarrow \Sigma \ell^+ \ell^-\) and \(\Xi_b \rightarrow \Xi \ell^+ \ell^-\), with \(\ell\) being \(\mu\) or \(\tau\), using the form factors calculated via light cone QCD in full theory. In calculations, the errors of form factors are taken into account. We compare the results obtained in leptoquark model with those of the standard model as well as the existing lattice QCD predictions and experimental data.
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