arXiv subjects

P. Naik

Publications and source records attributed to P. Naik.

41 records · Page 3Linked to original sources

arXiv2010

Measurement of the eta_b(1S) mass and the branching fraction for Upsilon(3S) --> gamma eta_b(1S)

We report evidence for the ground state of bottomonium, eta_b(1S), in the radiative decay Upsilon(3S) --> gamma eta_b in e^+e^- annihilation data taken with the CLEO III detector. Using 6 million Upsilon(3S) decays, and assuming Gamma(eta_b) = 10 MeV/c^2, we obtain B(Upsilon(3S) --> gamma eta_b) = (7.1 +- 1.8 +- 1.1) X 10^{-4}, where the first error is statistical and the second is systematic. The statistical significance is about 4 sigma. The mass is determined to be M(eta_b) = 9391.8 +- 6.6 +- 2.0 MeV/c^2, which corresponds to the hyperfine splitting Delta M_{hf}(1S)_b = 68.5 +- 6.6 +- 2.0 MeV/c^2. Using 9 million Upsilon(2S) decays, we place an upper limit on the corresponding Y(2S) decay, B(Y(2S) --> gamma eta_b) < 8.4 X 10^{-4} at 90 % confidence level.

hep-ex↗

arXiv2009

Observation of $η'$ decays to $π^+π^-π^0$ and $π^+π^-\e^+e^-$

Using psi(2S) --> pi+ pi- J/psi, J/psi --> gamma eta' events acquired with the CLEO-c detector at the CESR e+e- collider, we make the first observations of the decays eta' --> pi+ pi- pi0 and eta' --> pi+ pi- e+ e-, measuring absolute branching fractions (37 +11 -9 +- 4) x 10^-4 and (25 +12 -9 +- 5) x 10^-4, respectively. For eta' --> pi+ pi- pi0, this result probes the mechanism of isospin violation and the roles of pi0/eta/eta'-mixing and final state rescattering in strong decays. We also set upper limits on branching fractions for eta' decays to pi+ pi- mu+ mu-, 2(pi+ pi-), pi+ pi- 2pi0, 2(pi+ pi-)pi0, 3(pi+ pi-), and invisible final states.

hep-ex↗

arXiv2008

Improving the precision of gamma/phi_3 via CLEO-c Measurements

Quantum correlations in $ψ(3770) \to D^0\bar{D}^0$ provide unique access to information about strong phase differences. Precision determination of the CKM phase $γ/ϕ_3$ via $B \to D K$ decays depends upon constraints on charm mixing amplitudes, measurements of doubly-Cabibbo suppressed amplitudes and relative phases, and studies of correlated charmed meson decays tagged by flavor or CP eigenstates. CP-tagged $D^0 \to K^-π^+π^-π^+$ decays and CP-tagged $D^0 \to K^0_Sπ^+π^-$ Dalitz plots are only available at CLEO-c. Using the 818 pb$^{-1}$ CLEO-c data sample produced by the Cornell Electron Storage Ring (CESR) at $\sqrt{s} = 3.77$ GeV, we perform analyses of these decays. We describe the techniques used to measure the $D$-decay parameters, and the CLEO-c impact on measurements of $γ/ϕ_3$.

hep-ex↗

arXiv2008

Exclusive Baryon-Antibaryon Decays of the chi_cJ Mesons

Using a sample of 2.59 \times 10^7 psi(2S) decays collected by the CLEO--c detector, we present results of a study of chi_{cJ} (J=0,1,2) decays into baryon-antibaryon final states. We present the world's most precise measurements of the chi_cJ -> p-pbar and chi_cJ -> Lambda-Lambdabar branching fractions, and the first measurements of chi_c0 decays to other hyperons. These results illuminate the decay mechanism of the chi_c states.

hep-ex↗

arXiv2000

Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes

We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electromagnetic interactions with hadronic systems. We find a non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.

nucl-ex↗