Lepton polarization asymmetry in B->K((*))l(+)l(-)

[[abstract]]We investigate the longitudinal lepton polarization asymmetry in the exclusive processes B-->Kl(+)l(-) and B-->K*l(+)l(-). We include both short- and long-distance contributions to the asymmetry in our discussions. We find that average values of the polarization asymmetries of the muon and tau for B-->K(*)mu(+)mu(-) and B-->K(*)tau(+)tau(-) are -0.8 (-0.7) and -0.2 (-0.5), respectively.[[fileno]]2010129010044[[department]]物理

Constraints on a special running vacuum model

Funder: Physics Division, National Center for Theoretical Sciences; doi: http://dx.doi.org/10.13039/100009638AbstractWe study a special running vacuum model (RVM) with $$\Lambda = 3 \alpha H^2+3\beta H_0^4 H^{-2}+\Lambda _0$$Λ=3αH2+3βH04H-2+Λ0, where $$\alpha$$α, $$\beta$$β and $$\Lambda _0$$Λ0 are the model parameters and H is the Hubble one. This RVM has non-analytic background solutions for the energy densities of matter and radiation, which can only be evaluated numerically. From the analysis of the CMB power spectrum and baryon acoustic oscillation along with the prior of \alpha >0α&gt;0 to avoid having a negative dark energy density, we find that \alpha <2.83\times 10^{-4}α&lt;2.83×10-4 and $$\beta =(-0.2^{+3.9}_{-4.5})\times 10^{-4}$$β=(-0.2-4.5+3.9)×10-4 (95$$\%$$% C.L.). We show that the RVM fits the cosmological data comparably to the $$\Lambda \hbox {CDM}$$ΛCDM. In addition, we relate the fluctuation amplitude $$\sigma _8$$σ8 to the neutrino mass sum $$\Sigma m_\nu$$Σmν.</jats:p

Rare B Decays with a HyperCP Particle of Spin One

In light of recent experimental information from the CLEO, BaBar, KTeV, and Belle collaborations, we investigate some consequences of the possibility that a light spin-one particle is responsible for the three Sigma^+ -> p mu^+ mu^- events observed by the HyperCP experiment. In particular, allowing the new particle to have both vector and axial-vector couplings to ordinary fermions, we systematically study its contributions to various processes involving b-flavored mesons, including B-Bbar mixing as well as leptonic, inclusive, and exclusive B decays. Using the latest experimental data, we extract bounds on its couplings and subsequently estimate upper limits for the branching ratios of a number of B decays with the new particle. This can serve to guide experimental searches for the particle in order to help confirm or refute its existence.Comment: 17 pages, 3 figures; discussion on spin-0 case modified, few errors corrected, main conclusions unchange

Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

The decay channel $\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p})$ is studied using a sample of $1.06\times 10^8$ $\psi^\prime$ events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the $p\bar{p}$ invariant mass spectrum. The enhancement can be fit with an $S$-wave Breit-Wigner resonance function with a resulting peak mass of $M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2$ and a narrow width that is $\Gamma<38 {\rm MeV/}c^2$ at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics

Measurement of the matrix element for the decay η′→ηπ +π -

The Dalitz plot of η⊃′→ηπ⊃+π⊃- decay is studied using (225.2±2.8)×106 J/ψ events collected with the BESIII detector at the BEPCII e⊃+e⊃- collider. With the largest sample of η⊃′ decays to date, the parameters of the Dalitz plot are determined in a generalized and a linear representation. Also, the branching fraction of J/ψ→γη⊃′ is determined to be (4.84±0.03±0.24)×10⊃-3, where the first error is statistical and the second systematic. © 2011 American Physical Society.published_or_final_versio

First observation of the decays χcJ→π0π0π0π0

We present a study of the P-wave spin-triplet charmonium χ cJ decays (J=0, 1, 2) into π0π0π0π0. The analysis is based on 106×106 ψ⊃′ decays recorded with the BESIII detector at the BEPCII electron positron collider. The decay into the π0π0π0π0 hadronic final state is observed for the first time. We measure the branching fractions B(χ c0→π0π0π0π0)=(3.34±0. 06±0.44)×10⊃-3, B(χ c1→π0π0π0π0) =(0.57±0.03±0.08)×10⊃-3, and B(χ c2→π0π0π0π0)=(1.21±0.05±0.16) ×10⊃-3, where the uncertainties are statistical and systematical, respectively. © 2011 American Physical Society.published_or_final_versio