EuFe2_2As2_2 under high pressure: an antiferromagnetic bulk superconductor

We report the ac magnetic susceptibility $\chi_{ac}$ and resistivity $\rho$ measurements of EuFe$_2$As$_2$ under high pressure $P$. By observing nearly 100% superconducting shielding and zero resistivity at $P$ = 28 kbar, we establish that $P$-induced superconductivity occurs at $T_c \sim$~30 K in EuFe$_2$As$_2$. $\rho$ shows an anomalous nearly linear temperature dependence from room temperature down to $T_c$ at the same $P$. $\chi_{ac}$ indicates that an antiferromagnetic order of Eu$^{2+}$ moments with $T_N \sim$~20 K persists in the superconducting phase. The temperature dependence of the upper critical field is also determined.Comment: To appear in J. Phys. Soc. Jpn., Vol. 78 No.

Evidence for X(3872)->psi(2S)gamma in B-+/--> X(3872)K-+/- decays and a study of B -> cc gamma K

In a search for B -> cc gamma K decays with the BABAR detector, where cc> includes J/psi and psi(2S), and K includes K-+/-, K-S(0), and K-*(892), we find evidence for X(3872)-> J/psi gamma and X(3872)->psi(2S)gamma with 3.6 sigma and 3.5 sigma significance, respectively. We measure the product of branching fractions B(B-+/--> X(3872)K-+/-)xB(X(3872)-> J/psi gamma)=[2.8 +/- 0.8(stat)+/- 0.1(syst)]x10(-6) and B(B-+/--> X(3872)K-+/-)xB(X(3872)->psi(2S)gamma)=[9.5 +/- 2.7(stat)+/- 0.6(syst)]x10(-6)

Time-dependent and time-integrated angular analysis of B -> phi K-S(0)pi(0) and phi K-+/-pi(-/+)

We perform a time-dependent and time-integrated angular analysis of the decays B-0 -> phi K*(892)(0), phi K-2*(1430)(0), and phi(K pi)(0)*(0) with the final sample of about 465 x 10(6) B (B) over bar pairs recorded with the BABAR detector. Twenty-four parameters are investigated, including the branching fractions, CP-violation parameters, and parameters sensitive to final-state interactions. We use the dependence on the K pi invariant mass of the interference between the scalar and vector or tensor components to resolve discrete ambiguities of the strong and weak phases. We use the time evolution of the B -> phi K-S(0)pi(0) channel to extract the CP-violation phase difference Delta phi(00) = 0.28 +/- 0.42 +/- 0.04 between the B and (B) over bar decay amplitudes. When the B -> pi K-+/-pi(-/+) channel is included, the fractions of longitudinal polarization f(L) of the vector-vector and vector-tensor decay modes are measured to be 0.494 +/- 0.034 +/- 0.013 and 0.901(-0.058)(+0.046) +/- 0.037, respectively. This polarization pattern requires the presence of a positive-helicity amplitude in the vector-vector decay from a currently unknown source

Measurement of time dependent CP asymmetry parameters in B0 meson decays to ωKS0, η′K0, and π0KS0

We present measurements of the time-dependent CP-violation parameters S and C in the decays B0→ωKS0, B0→η′K0, reconstructed as η′KS0 and η′KL0, and B0→π0KS0. The data sample corresponds to the full BABAR dataset of 467×10^6 BB̅ pairs produced at the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center. The results are SωKS0=0.55-0.29+0.26±0.02, CωKS0=-0.52-0.20+0.22±0.03, Sη′K0=0.57±0.08±0.02, Cη′K0=-0.08±0.06±0.02, Sπ0KS0=0.55±0.20±0.03, and Cπ0KS0=0.13±0.13±0.03, where the first errors are statistical and the second systematic. These results are consistent with our previous measurements and the world average of sin⁡2β measured in B0→J/ψKS0

Search for B-meson decays to b(1 rho) and b(1)K

We present a search for decays of B mesons to final states with a b(1) meson and a rho or K*(d892) meson. The search is based on a data sample consisting of 465 million B (B) over bar pairs collected by the BABAR detector at the SLAC National Accelerator Laboratory. We do not observe any statistically significant signal. The upper limits we set on the branching fractions range from 1.4 to 8.0 x 10(-6) at the 90% confidence level, including systematic uncertainties

Measurements of the tau mass and the mass difference of the tau(+) and tau(-) at BABAR

We present the result from a precision measurement of the mass of the tau lepton, M-tau, based on 423 fb(-1) of data recorded at the Upsilon(4S) resonance with the BABAR detector. Using a pseudomass endpoint method, we determine the mass to be 1776.68 +/- 0.12(stat)+/- 0.41(syst) MeV. We also measure the mass difference between the tau(+) and tau(-), and obtain (M-tau(+)-M-tau(-))/M-AVG(tau)=(-3.4 +/- 1.3(stat)+/- 0.3(syst))x10(-4), where M-AVG(tau) is the average value of M-tau(+) and M-tau(-)

Measurement of branching fractions of B decays to K-1(1270)pi and K-1(1400)pi and determination of the CKM angle alpha from B-0 -> a(1)(1260)(+/-)pi(-/+)

We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K-1(1270) or K-1(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454 x 10(6) B (B) over bar pairs produced in e(+)e(-) annihilation. We measure the branching fractions B(B-0 -> K-1(1270)(+)pi(-) + K-1(1400)(+)pi(-)) = 3.1(-0.7)(+0.8) x 10(-5) and B(B+ -> K-1(1270)(0)pi(+) + K1(1400)(0)pi(+)) = 2.9(-1.7)(+2.9) x 10(-5) ( a(1)(1260)(+/-)pi(-/+) decays

Precise measurement of the e(+)e(-)->pi(+)pi(-)(gamma) cross section with the initial state radiation method at BABAR

A precise measurement of the cross section of the process e(+)e(-)->pi(+)pi(-)(gamma) from threshold to an energy of 3 GeV is obtained with the initial state radiation (ISR) method using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e(+)e(-)->mu(+)mu(-)gamma(gamma). The leading-order hadronic contribution to the muon magnetic anomaly calculated using the pi pi cross section measured from threshold to 1.8 GeV is (514.1 +/- 2.2(stat)+/- 3.1(syst))x10(-10)