相关论文: Light Gluinos and $\Gamma(Z\rightarrow b\overline{…
The light gluino (12 - 16 GeV) and light sbottom (2 - 6 GeV) scenario has been used to explain the apparent overproduction of b-quarks at the Tevatron. This scenario also predicts the decay Z -> b b-bar ~g ~g where the gluinos subsequently…
We study the light gluino scenario giving special attention to constraints from the masses of the light CP-even neutral Higgs $m_h$, the lightest chargino $m_{\chi^{\pm}_1}$, and the second lightest neutralino $m_{\chi^0_2}$, and from the…
The rare decay $b \to s \gamma$ is studied in the left-right supersymmetric model. We give explicit expressions for all the amplitudes associated with the supersymmetric contributions coming from gluinos, charginos and neutralinos in the…
Using the new CLEO bound on the branching ratio of the decay mode $b\longrightarrow s\gamma$ given by $1\times10^{-4}< B(b\longrightarrow s\gamma)<4\times10^{-4}$ at 95\% c.l., and the experimental bounds on the masses of the lightest…
We investigate the impact of a light gluino, which might have escaped detection at colliders, on inclusive radiative $B$-decays mediated through penguin-like diagrams. We find that the viability of the scenario depends largely on the…
The effective interaction for two neutrino, two photon coupling is used to find an approximate width for the decay of the Z boson into the nu nubar gamma gamma final state.
The results of calculation of light gluino contributions to Gamma(Z--->hadrons) and Gamma(tau--->hadrons) to O(alpha_s^3) are presented. The net effect in the case of Z decay is noticeable. For the tau width the effect is very large and, if…
The discrepancy between the measured and theoretical production cross section of $b$ quarks at the Tevatron can probably be explained by the recently proposed scenario of light gluinos of mass 12-16 GeV and light sbottoms of mass $2-5.5$…
The $Z^0 \to b\bar b$ width, $\Gamma_b$, is analysed in conjunction with the total and hadronic $Z^0$ widths, $\Gamma_T$ and $\Gamma_h$. Assuming, tentatively, that the present 2$\sigma$ discrepancy in $\Gamma_b$ will substantiate as time…
We investigate constraints from the observed branching ratio for b -> s gamma and fine-tuning in the framework of natural supersymmetry. The natural supersymmetry requires the large trilinear coupling of the stop sector, light higgsinos (a…
It is analyzed the branching ratio $B(b\rightarrow s\gamma)$ in the context of minimal $N=1$ supergravity with radiatively broken electroweak symmetry group. There is a strong dependence on supersymetric parameters, but constraints on the…
The $b \rightarrow s l^+ l^-$ process is studied in the minimal supergravity model in detail. Taking account of the long distance contributions from the $c\overline{c}$ resonances, we calculate the branching ratio and the lepton…
We re-examine the possible magnitude of the supersymmetric contribution to $R_b\equiv\Gamma(Z^0\to\bar b b)/\Gamma(Z^0\to{\rm all})$ in the light of the constraints imposed by the absence of light charginos at LEP~1.5, implementing also…
It is widely thought that increasing bounds on the gluino mass, which feeds down to the stop mass through renormalization group running, are making a light stop increasingly unlikely. Here we present a counter-example. We examine the case…
Minimal $N=1$ supergravity with a radiatively broken electroweak symmetry group is studied in the light gluino scenario. Constraints from the $b\rightarrow s\gamma$ decay and from the masses of the light CP-even neutral Higgs $m_h$, the…
Implications of a 2 - 5.5 GeV sbottom and 12 - 16 GeV gluino masses for rare B decay phenomenology are discussed. An effective Hamiltonian is constructed in which the gluinos are integrated out and a \tilde{b} squark remains among the light…
A gluino in the mass range 12--16 GeV combined with a light (2--5.5 GeV) bottom squark, as has been proposed recently to explain an excess of b quark hadroproduction, would affect the momentum-scale dependence (``running'') of the strong…
In this paper, I study the branching ratio of the rare radiative decay $B_s \to \nu \bar{\nu} \gamma$ in the framework of the Fourth-Generation Standard Model and the Two-Higgs-Doublet Model. It is shown that this quantity is a very…
The scenario of light gluinos and light sbottoms was advocated to explain the discrepancy between the measured and theoretical production of $b$ quarks at the Tevatron. This scenario will have model-independent predictions for $Z\to q\bar q…
Using the light cone QCD Sum Rules Method, we study the rare B -> nu barnu gamma decay and and find that the branching ratios are, B(B_s -> nu barnu gamma) = 7.5 10^{-8}, B(B_d -> nu -> nu gamma) = 4.2 10^{-9}. A comparision of our results,…