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Register a new user$tau$ Polarization in SUSY Cascade Decays
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$tau$ leptons emitted in cascade decays of supersymmetric particles are polarized. The polarization may be exploited to determine spin and mixing properties of the neutralinos and stau particles involved.
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We explore how the polarization of the tau leptons in the cascade decay $tilde{q}to qtildechi^0_2to qtautildetauto qtautautildechi^0_1$ can be exploited to study mixing properties of neutralinos and staus. We present details of the analysis including experimental effects such as transverse momentum cuts for the $tautopi u$ decay mode, and show that the di-pion invariant mass distribution provides valuable information on their properties.
This article summarizes recent developments in $Bto D^{(ast)}tau u$ decays. We explain how to extract the tau leptons production properties from the kinematics of its decay products. The focus is on hadronic tau decays, which are most sensitive to the tau polarizations. We present new results for effects of new physics in tau polarization observables and quantify the observation prospects at BELLE II.
Beyond the Standard Model scenarios with extensions of the Higgs sector typically predict new resonances that can undergo a series of cascade decays to detectable Standard Model particles. On one hand, sensitivity to such signatures will contribute to the full reconstruction of the extended Higgs potential if a new physics discovery will be made. On the other hand, such cascade decays could be dominant decay channels, thus being potentially the best motivated signatures to achieve a new physics discovery in the first place. In this work, we show how the long short-term memory that is encoded in the cascade decays phenomenology can be exploited in discriminating the signal from the background, where no such information is present. In parallel, we demonstrate for theoretically motivated scenarios that such an approach provides improved sensitivity compared to more standard analyses, where only information about the signals final state kinematics is included.
The meson decays $Bto Dtau u$ and $Bto D^* tau u$ are sensitive probes of the $bto ctau u$ transition. In this work we present a complete framework to obtain the maximum information on the physics of $Bto D^{(*)}tau u$ with polarized $tau$ leptons and unpolarized $D^{(*)}$ mesons. Focusing on the hadronic decays $tauto pi u$ and $tautorho u$, we show how to extract seven $tau$ asymmetries from a fully differential analysis of the final-state kinematics. At Belle II with $50~text{ab}^{-1}$ of data, these asymmetries could potentially be measured with percent level statistical uncertainty. This would open a new window into possible new physics contributions in $bto ctau u$ and would allow us to decipher its Lorentz and gauge structure.
An exhaustive number of QCD finite energy sum rules for $tau$-decay together with the latest updated ALEPH data is used to test the assumption of global duality. Typical checks are the absence of the dimension $d=2$ condensate, the equality of the gluon condensate extracted from vector or axial vector spectral functions, the Weinberg sum rules, the chiral condensates of dimensions $d=6$ and $d=8$, as well as the extraction of some low-energy parameters of chiral perturbation theory. Suitable pinched linear integration kernels are introduced in the sum rules in order to suppress potential quark-hadron duality violations and experimental errors. We find no compelling indications of duality violations in hadronic $tau$-decay in the kinematic region above $ssimeq2.2$ GeV$^{2}$ for these kernels.
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