Top-squark mixing effects in the supersymmetric electroweak corrections to top quark production at the Tevatron

Taking into account the mixing effects between left- and right-handed top-squarks, we calculate the genuine supersymmetric eletroweak correction to top quark production at the Tevatron in the minimal supersymmetric model. The analytic expressions of the corrections to both the parton level cross section and the total hadronic cross section are presented. Some numerical examples are also given to show the size of the corrections.Comment: 11 pages, 3 figures, available at reques

The signatures of the new particles h2h_2 and ZμτZ_{\mu\tau} at e-p colliders in the U(1)Lμ−LτU(1)_{L_\mu-L_\tau} model

Considering the superior performances of the future e-p colliders, LHeC and FCC-eh, we discuss the feasibility of detecting the extra neutral scalar $h_{2}$ and the light gauge boson $Z^{}_{\mu\tau}$, which are predicted by the ${U(1)}_{L^{}_{\mu} - L^{}_{\tau}}$ model. Taking into account the experimental constraints on the relevant free parameters, we consider all possible production channels of $h_{2}$ and $Z^{}_{\mu\tau}$ at e-p colliders and further investigate their observability through the optimal channels in the case of the beam polarization P($e^{-}$)= -0.8. We find that the signal significance above 5$\sigma$ of $h_{2}$ as well as $Z^{}_{\mu\tau}$ detecting can be achieved via $e^{-}p\to{e^{-}jh_{2}(\to{Z_{\mu\tau}Z_{\mu\tau}})}\to~e^{-}j+/\!\!\!\!{E}^{}_{T}$ process and a 5$\sigma$ sensitivity of $Z^{}_{\mu\tau}$ detecting can be gained via $e^{-}p\to{e^{-}jh_{1}(\to{Z^{}_{\mu\tau}Z^{}_{\mu\tau}})\to}~e^{-}j+/\!\!\!\!{E}^{}_{T}$ process at e-p colliders with appropriate parameter values and a designed integrated luminosity. However, the signals of $h_{2}$ decays into pair of SM particles are difficult to be detected.Comment: 22 pages, 9 figures, references added and typos are correcte

Quality of Bureaucracy and Open-Economy Macro Policies

Bureaucratic quality in terms of the level of corruption varies widely across countries, and is in general slow to evolve relative to the speed with which many economic polices can be implemented such as the imposition of capital controls. In this paper, we study the possibility that quality of bureaucracy may be an important structural determinant of open-economy macro-policies, in particular, the imposition/removal of capital controls, and financial repression. We first derive a model that delivers such a result. Bureaucratic corruption translates into reduced ability by the government to collect tax revenue. Even if capital control/financial repression is otherwise inefficient, as long as the government needs the revenue for public goods provision, it would have to rely more on capital control/financial repression. For all countries for which we can obtain relevant data, we find that more corrupt countries are indeed more likely to impose capital controls, a pattern consistent with the model's prediction. The result of this paper suggests that a premature removal of capital controls mandated by outside institutions could reduce rather than enhance economic efficiency.

The quality of bureaucracy and capital account policies

The extent of bureaucracy varies extensively across countries, but the quality of bureaucracy within a country changes more slowly than economic policies. The authors propose that the quality of bureaucracy may be an important structural determinant of open economy macroeconomic policies - especially the imposition or removal of capital control. In their model, capital controls are an instrument of financial repression. They entail efficiency loss for the economy but also generate implicit revenue for the government. The results show that bureaucratic corruption translates into the government's reduced ability to collect tax revenues. Even if capital controls and financial repression are otherwise inefficient, the government still has to rely on them to raise revenues to provide public goods. Among the countries for which the authors could get relevant data, they find that the more corrupt ones are indeed more likely to impose capital controls, a pattern consistent with the model's prediction. To deal with possible reverse causality, they use the extent of corruption in a country's judicial system, and the degree of democracy, as the instrumental variables for bureaucratic corruption. The instrumental variable regressions show the same result: more corrupt countries are associated with more severe capital controls. The results suggest that as countries develop and improve their public institutions, reducing bureaucratic corruption over time, they will choose to gradually liberalize their capital accounts. Removing capital controls prematurely when forced by outside institutions to do so could reduce rather than improve their economic efficiency.Banks&Banking Reform,Governance Indicators,Environmental Economics&Policies,Economic Theory&Research,National Governance

Next-to-leading order QCD predictions for associated production of top squarks and charginos at the CERN LHC

We present the calculations of the complete next-to-leading order (NLO) inclusive total cross sections for the associated production processes $pp\to \tilde{t}_i\tilde{\chi}_k^-+X$ in the Minimal Supersymmetric Standard Model at the CERN Large Hadron Collider. Our calculations show that the total cross sections for the $\tilde{t}_1\tilde{\chi}_1^-$ production for the lighter top squark masses in the region 100 GeV $< m_{\tilde{t}_1}<$ 160 GeV can reach 1 pb in the favorable parameter space allowed by the current precise experiments, and in other cases the total cross sections generally vary from 10 fb to several hundred fb except both $m_{\tilde{t}_1}>$ 500 GeV and the $\tilde{t}_2\tilde{\chi}_2^-$ production channel. Moreover, we find that the NLO QCD corrections in general enhance the leading order total cross sections significantly, and vastly reduce the dependence of the total cross sections on the renormalization/factorization scale, which leads to increased confidence in predictions based on these results.Comment: 42 pages, 13 figures, RevTex4. Journal-ref adde