Potential for a new muon g-2 experiment

A new experiment to measure the muon g-2 factor is proposed. We suppose the sensitivity of this experiment to be about 0.03 ppm. The developed experiment can be performed on an ordinary storage ring with a noncontinuous field created by usual magnets. When the total length of straight sections of the ring is appropriate, the spin rotation frequency becomes almost independent of the particle momentum. In this case, a high-precision measurement of an average magnetic field can be carried out with polarized proton beams. A muon beam energy can be arbitrary. Possibilities to avoid a betatron resonance are analyzed and corrections to the g-2 frequency are considered.Comment: 5 pages, 1 figur

Study of the η\etaN scattering amplitude through the associated photoproduction of ϕ\phi- and η\eta-mesons in the region of the N*(1535) resonance

The $\gamma p \to \phi \eta p$ reaction is studied in the kinematic region where the $\eta p$ final state originates dominantly from the decay of the N*(1535) resonance. The threshold laboratory photon energy for this reaction (at the peak of the S11 resonance) is $E_\gamma^{Lab} =$3 GeV. We will discuss it somewhat above threshold, at $E_\gamma^{Lab}\simeq 4-5$ GeV, in order to reach lower (absolute) values of the squared 4-momentum transfer from the initial photon to the final $\phi$-meson. In these conditions, we expect the t-channel $\pi^0$- and $\eta$-meson exchanges to drive the dynamics underlying the $\gamma p \to \phi \eta p$ process. The initial photon dissociates into the final $\phi$-meson and a virtual pseudoscalar meson ($\pi^0$ or $\eta$). The virtual pseudoscalar meson scatters from the proton target to produce the final $\eta p$ state. The $\pi^0 p \to \eta p$ and $\eta p \to \eta p$ amplitudes are derived in the framework of a coupled-channel effective field theory of meson-baryon scattering. We found the $\eta$-meson exchange to be largely dominant. The $\eta$-$\pi^0$ interference is of the order of $20 - 30$. The sign of this term is not known and has a significant influence on the results. The $\pi N\to \eta N$ amplitude being largely determined by data on the $\pi^- p \to \eta n$ reaction, we found that the $\gamma p \to \phi \eta p$ reaction cross section is rather directly related to the $\eta$-nucleon scattering amplitude in the N*(1535) resonance region. Accurate data on the $\gamma p \to \phi \eta p$ process would therefore put additional constraints on this still poorly known amplitude.Comment: 13 pages, 8 figure

Measurement of coherent ϕ-meson photoproduction from the deuteron at low energies

The cross section and decay angular distributions for the coherent ϕ-meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer t=(pγ−pϕ)2=−2 GeV2/c2, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are compared with predictions from a rescattering model. In a framework of vector meson dominance, the data are consistent with the total ϕ-N cross section σϕN at about 10 mb. If vector meson dominance is violated, a larger σϕN is possible by introducing a larger t slope for the ϕN→ϕN process than that for the γN→ϕN process. The decay angular distributions of the ϕ are consistent with helicity conservation

In situ Raman spectroscopy of cubic boron nitride to 90GPa and 800K

AbstractThe temperature and pressure dependences of the Raman spectrum of the transverse-optical mode of cubic boron nitride were calibrated for applications to a Raman spectroscopy pressure sensor in optical cells to about 800K and 90GPa. A significant deviation from linearity of the pressure dependence is confirmed at pressures above 20GPa. At ambient temperature, dv/dP slopes are 3.41(7) and 2.04(7) cm−1/GPa at 0 and 90GPa, respectively. A polynomial expression is used to fit the pressure–temperature dependence of the Raman line. The pressure dependence does not significantly change with temperature, as determined from experiments conducted up to 800K. At 0GPa, the dv/dP slope is 3.46(7)cm−1/GPa at 800K. At pressures above 90GPa, the Raman spectrum of the transverse-optical mode cannot be observed because of an overlap of the signals of cubic boron nitride and diamond used as the anvils in the high-pressure cell

Photonic SUSY Two-Loop Corrections to the Muon Magnetic Moment

Photonic SUSY two-loop corrections to the muon magnetic moment are contributions from diagrams where an additional photon loop is attached to a SUSY one-loop diagram. These photonic corrections are evaluated exactly, extending a leading-log calculation by Degrassi and Giudice. Compact analytical expressions are provided and the numerical behaviour is discussed. The photonic corrections reduce the SUSY one-loop result by 7...9%. The new terms are typically around ten times smaller than the leading logarithms, but they can be larger and have either sign in cases with large SUSY mass splittings. We also provide details on renormalization and regularization and on how to incorporate the photonic corrections into a full SUSY two-loop calculation.Comment: 25 page

Magnetic interaction induced by the anomaly in kaon-photoproductions

We study the role of magnetic interaction in the photoproduction of the kaon and hyperon. We find that the inclusion of a higher order diagram induced by the Wess-Zumio-Witten term has a significant contribution to the magnetic amplitude, which is compatible to the observed photon asymmetry in the forward angle region. This enables us to use the K^* coupling constants which have been determined in a microscopic way rather than the phenomenological ones which differ largely from the microscopic ones.Comment: 8 pages, 3 figure

Status of KLOE-2

In a few months the KLOE-2 detector is expected to start data taking at the upgraded DA$\rm{\Phi}$NE $\phi$-factory of INFN Laboratori Nazionali di Frascati. It aims to collect 25 fb$^{-1}$ at the $\phi(1020)$ peak, and about 5 fb$^{-1}$ in the energy region between 1 and 2.5 GeV. We review the status and physics program of the projectComment: 6 pages, 5 figures, to appear in the Proceedings of the PHIPSI09 Workshop, Oct 13-16, 2009, Beijing, Chin

A Pair Polarimeter for Linearly Polarized High Energy Photons

A high quality beam of linearly polarized photons of several GeV will become available with the coherent bremsstrahlung technique at JLab. We have developed a polarimeter which requires about two meters of the beam line, has an analyzing power of 20% and an efficiency of 0.02%. The layout and first results of a polarimeter test on the laser back-scattering photon beam at SPring-8/LEPS are presented

New results on the hadronic vacuum polarization to the muon g-2

Results on the lowest-order hadronic vacuum polarization contribution to the muon magnetic anomaly are presented. They are based on the latest published experimental data used as input to the dispersion integral. Thus recent results on tau to nutau pi pi0 decays from Belle and on e+ e- annihilation to pi+ pi- from BABAR and KLOE are included. The new data, together with improved isospin-breaking corrections for tau decays, result into a much better consistency among the different results. A discrepancy between the Standard Model prediction and the direct g-2 measurement is found at the level of 3 sigma.Comment: proceedings of the PhiPsi09 conference, Oct. 13-16, 2009, Beijing, Chin