相关论文: Polarization in (quasi-)two-body decays and new ph…
Polarization measurements provide a detailed method to test the Standard Model and to search for new physics. Most previous studies depend on pre-selected coordinates, which blurs the significance of the results. The construction of two…
We discuss a formalism for the spin correlations and polarizations in two-particle systems with spins half-half, half-one and one-one, and provide the connections between the polarizations and correlations with the joint angular…
We perform an analysis of two-body non leptonic decays of $B$ and $B_s$ mesons in the factorization approximation. We make use of the semileptonic decay amplitudes previously calculated on the basis of an effective lagrangian satisfying…
We demonstrate that polarization measurements in exclusive semileptonic B decays are powerful tools for unraveling non-standard model sources of T-violation. Measurements of the transverse polarization of the tau lepton in the B to D tau nu…
In this study, the nonleptonic two-body $B$ decays into two tensor mesons (including $a_2(1320)$, $K^*_2(1430)$, $f_2(1270)$, $f^\prime_2(1525)$, denoted generically as $T$) are investigated in the QCD factorization approach. The branching…
Semi-leptonic and leptonic decays of B-mesons are important probes for testing SM and theories beyond it because of their relative cleanliness and far less theoretical uncertainties. In semi-leptonic decays based on quark level transition…
In 2017, LHCb collaboration reported their first observation of the rare decays $B_s \to \phi (f_0(980)$ $/f_2(1270) \to ) \pi^+\pi^-$ and the evidence of $B^0 \to \phi(f_0(980)/f_2(1270)\to)\pi^+\pi^-$. Motivated by this, we study these…
The paper gives the polarization of the tau lepton in the semileptonic B decays with respect to the direction of the virtual W boson. The result is given including the nonperturbative HQET corrections.The perturbative QCD corrections are…
We investigate the weak semileptonic decays of the charmonium $J/\psi$ and bottomonium $\Upsilon(1S)$ into a pseudoscalar meson, namely, the $J/\psi\to D_{(s)}\ell\bar{\nu}_\ell$ and $\Upsilon(1S)\to B_{(c)}\ell\bar{\nu}_\ell$ decays. We…
In this paper, we examine B -> VT decays (V is a vector and T is a tensor meson), whose final-state particles can have transverse or longitudinal polarization. Measurements have been made of B -> \phi K_2^*, and it is found that fT/fL is…
We study the single and double lepton polarization asymmetries in the semileptonic $B$ meson decays $B \to K_1 (1270) \ell^+ \ell^-$ $\ell \equiv e$, $\mu$, $\tau$), where the strange $P$-wave meson, $K_1(1270)$, is the mixtures of the…
In this work we will study the longitudinal polarisations of both leptons in the decay process ${\bar B} \to {\bar K}_2(1430)\, \ell^+ \, \ell^-$. This process has all the features of the related and well investigated process ${\bar B} \to…
We propose two different and complementary observables for singling out possible signals of physics beyond the standard model in the semi-leptonic decays $\Lambda_b \to \Lambda_c \ell{\bar \nu}_{\ell}$, both with the $\tau$ lepton and with…
We consider measurements of exclusive rare semi-tauonic $b$-hadron decays, mediated by the $b \rightarrow s \tau^+ \tau^-$ transition, at a future high energy circular electron-positron collider (FCC-$ee$). We argue that the high boosts of…
Determining the spin of any new particle and measuring its couplings to other particles and/or itself are crucial in reconstructing the structure of any quantum field theory containing the particle. A general helicity formalism is employed…
We provide a general analysis of time reversal invariance violation in the exclusive semileptonic B decays B to D l nu and B to D* l nu. Measurements of the lepton and D* polarizations can be used to search for and identify non-standard…
We study inelastic two-body relaxation in a spin-polarized ultracold Fermi gas in the presence of a p-wave Feshbach resonance. It is shown that in reduced dimensionalities, especially in the quasi-one-dimensional case, the enhancement of…
Polarized $\Lambda_b \to \Lambda \gamma$ decays at the Z pole are shown to be well suited for probing a large variety of New Physics effects. A new observable is proposed, the angular asymmetry between the $\Lambda_b$ spin and photon…
Determining the spin of any new particle is critical in identifying the true theory among various extensions of the Standard Model (SM). The degree of $Z$-boson polarization in any two-body decay process $A\to B Z$ is sensitive to the spin…
At the kinematic endpoint of zero recoil physical momenta are parallel which leads to symmetries in the decay distributions. We implement this observation for decays of the type $A \to (B_1 B_2) C$ by extending the helicity formalism to…