Narrow Results

New physics search is a part of 30 years of BES physics program, which started during BESII days. The richness of physics features in the τ-charm energy region enabled many published results. At BESIII, the clean environments, high luminosity and excellent detector performance provide ideal opportunities for searches for new physics beyond standard model. Though most obtained upper limits are still above than the SM predictions, they may help to discriminate the different new physics models or to constrain the parameters in the different physics models. With the accumulation of large data sets and possible increase of luminosity and cms energy, as well as an ever-improving understanding of the detector performance, BESIII will have great potential in NP searches in the coming years.

We have updated theoretical studies of heavy vector quarkonium production, including J/Ψ, Ψ′ and ϒ, in the exclusive W-boson decays. Particularly, in the standard model the branching fraction of $W^{-}\to J/\text{Ψ}{\ell }^{-}{\overline{\nu }}_{\ell }(\ell =e \text{or} \mu )$ has been predicted to be about 8.5 × 10⁻⁷, which is substantially larger than those of two-body hadronic radiative W decays. Thus in the future high-luminosity experimental facilities, this rare channel could be very useful to search for the exclusive W-boson decays containing the hadronicfinal state. Furthermore, the surprisingly large decay rate can be explained by an electromagnetic fragmentation formalism. We have analyzed the lepton fragmentation and the photon fragmentation processes, and calculated their contributions to the differential decay rate of $W^{-}\to J/\text{Ψ}{\ell }^{-}{\overline{\nu }}_{\ell }$ in the fragmentation limit. It is found that the fragmentation contribution agrees well with the result from the full calculation.

The E391a experiment to search for the decay was successfully performed at the 12 GeV KEK-PS accelerator and had data-taking three times in 2004-2005. One week of data of the Run-1 was analyzed to understand of quality of data, and a new upper limit on the branching ratio was set to be 2.1 × 10^-7. We extended our analysis to a 1/3 sample of Run-1 and to a one week data of the Run-2 sample.

DØ has searched for flavor changing neutral currents in the decay modes D⁺ → π⁺μ⁺μ^-, and . No significant signal is seen in any of these decay modes and upper limits are set.

Purely leptonic decays of the B meson are important predictions of the Standard Model, but have not been observed. We present the results of recent BaBar searches for the decays B⁺ → ℓ⁺ν_ℓ where ℓ = e, μ, τ. We also present the results of a search for the rare radiative leptonic decay B⁰ → ℓ⁺ℓ^-γ, where ℓ = e, μ. We find no evidence for these decays and proceed to set upper limits on their branching ratios.

Will supersymmetry be found at the CERN Large Hadron Collider (LHC)? If it is, which supersymmetric model is chosen by Nature? Will the available data be enough to sort these puzzles out?

Addressing these questions in this work, we show that the next-to-minimal version of the popular supergravity motivated model (NmSuGra) has a good chance to be observed at the LHC. We also demonstrate that regions of the NmSuGra parameter space which the LHC cannot reach will be detectable at upgraded versions of WIMP direct detection experiments, such as super-CDMS.

This article contains a summary of results obtained by the LHCb experiment at CERN concerning CP violation and rare decays of b quarks, obtained from 7-8 TeV pp collisions at the LHC. Particular attention is given to recent constraints to new physics beyond the Standard Model, derived from observations of precision observables involving leptonic final states. These include dimuon decays of B-mesons, b → sμ⁺μ⁻ transitions, and first precision measurements of the CKM matrix phases β_s and γ.