The H1 Forward Proton Spectrometer at HERA

The forward proton spectrometer is part of the H1 detector at the HERA collider. Protons with energies above 500 GeV and polar angles below 1 mrad can be detected by this spectrometer. The main detector components are scintillating fiber detectors read out by position-sensitive photo-multipliers. These detectors are housed in so-called Roman Pots which allow them to be moved close to the circulating proton beam. Four Roman Pot stations are located at distances between 60 m and 90 m from the interaction point.Comment: 20 pages, 10 figures, submitted to Nucl.Instr.and Method

Measurement of Interfering K^*+K^- and K^*-K^+ Amplitudes in the Decay D^0 --> K^+K^-pi^0

We have studied the Cabibbo-suppressed decay mode D^0 into K^+ K^- pi^0 using a Dalitz plot technique and find the strong phase difference delta_D [defined as delta_(K*^- K^+) - delta_(K*^+ K^-)] = 332 degrees +- 8 degrees +- 11 degrees and relative amplitude r_D [defined as a_(K*^- K^+) / a_(K*^+ K^-)] = 0.52 +- 0.05 +- 0.04. This measurement indicates significant destructive interference between D^0 into K^+ (K^- pi^0)_K*^- and D^0 into K^- (K^+ pi^0)_K*^+ in the Dalitz plot region where these two modes overlap. This analysis uses 9.0 fb^(-1) of data collected at s^(1/2) of approximately 10.58 GeV with the CLEO III detector.Comment: 10 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006/, Submitted to Phys. Rev. D (Rapid Communications

Update of the measurement of the cross section for e^+e^- -> psi(3770) -> hadrons

We have updated our measurement of the cross section for e^+e^- -> psi(3770) -> hadrons, our publication "Measurement of sigma(e^+e^- -> psi(3770) -> hadrons) at E_{c.m.} = 3773 MeV", arXiv:hep-ex/0512038, Phys.Rev.Lett.96, 092002 (2006). Simultaneous with this arXiv update, we have published an erratum in Phys.Rev.Lett.104, 159901 (2010). There, and in this update, we have corrected a mistake in the computation of the error on the difference of the cross sections for e^+e^- -> psi(3770) -> hadrons and e^+e^- -> psi(3770) -> DDbar. We have also used a more recent CLEO measurement of cross section for e^+e^- -> psi(3770) -> DDbar. From this, we obtain an upper limit on the branching fraction for psi(3770) -> non-DDbar of 9% at 90% confidence level.Comment: 3 pages, 0 figures. This is an erratum to Phys.Rev.Lett.96:092002,2006. Added a reference

Search for Radiative Decays of Upsilon(1S) into eta and eta'

We report on a search for the radiative decay of Upsilon(1S) to the pseudoscalar mesons eta and etaprime in 21.2 +/- 0.2 times 10^6 Upsilon(1S) decays collected with the CLEO III detector at the Cornell Electron Storage Ring (CESR). The eta meson was reconstructed in the three modes eta to gamma-gamma, eta to pi+pi-pi0 and eta to 3pi0. The etaprime meson was reconstructed in the mode etaprime to pi+ pi- eta with eta decaying through any of the above three modes, and also etaprime to gamma rho, where rho decays to pi^+ pi^-. Five out of the seven sub-modes are found to be virtually background-free. In four of them we find no signal candidates and in one Upsilon(1S) to gamma-etaprime, etaprime to pi+ pi- eta, eta to pi+pi-pi0 there are two good signal candidates, which is insufficient evidence to claim a signal. The other two sub-modes eta to gamma-gamma and etaprime to gamma rho are background limited, and show no excess of events in their signal regions. We combine the results from different channels and obtain upper limits at the 90% C.L. which are B(Upsilon(1S) to gamma eta) < 1.0 times 10^-6 and B(Upsilon(1S) to gamma etaprime) < 1.9 times 10^-6. Our limits are an order of magnitude tighter than the previous ones and below the predictions made by some theoretical models.Comment: 14 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2007/, Submitted to PR

A Study of Exclusive Charmless Semileptonic B Decays and Extraction of |V_{ub}| at CLEO

We have studied semileptonic B decay to the exclusive charmless states pi, rho/omega, eta and eta' using the full 15.5 fb^-1 CLEO Upsilon(4S) sample, with measurements performed in subregions of phase space to minimize dependence on a priori knowledge of the form factors involved. We find total branching fractions B(B^0 -> pi^-l^+nu) = (1.37 +- 0.15_stat +- 0.11_sys) x 10^-4 and B(B^0 -> rho^- l^+ nu) = (2.93 +- 0.37_stat +- 0.37_sys) x 10^-4. We find evidence for B^+ -> eta' l^+ nu, with B(B^+ -> eta' l^+ nu) = (2.66 +- 0.80_stat +- 0.56_sys) x 10^-4 and 1.20 x 10^-4 eta' l^+ nu) < 4.46 x 10^-4 (90% CL). We also limit B(B^+ -> eta l^+ nu) < 1.01 x 10^-4 (90% CL). By combining our B -> pi l nu information with unquenched lattice calculations, we find |V_ub| = (3.6 +- 0.4 +- 0.2 +0.6 -0.4) x 10^-3, where the errors are statistical, experimental systematic, and theoretical systematic, respectively.Comment: 35 pages, 15 figures; revise

Absolute Branching Fraction Measurements for D^+ and D^0 Inclusive Semileptonic Decays

We present measurements of the inclusive branching fractions for the decays D^+ -> X e^+ nu_e and D^0 -> X e^+ nu_e, using 281 pb^-1 of data collected on the psi(3770) resonance with the CLEO-c detector. We find Br(D^0 ->Xe^+\nu_e) = (6.46 \pm 0.17 \pm 0.13)% and Br((D^+ -> Xe^+nu_e) = (16.13 \pm 0.20 \pm 0.33)%. Using the known D meson lifetimes, we obtain the ratio Gamma{D^+}^sl/Gamma_{D^0}^sl= 0.985\pm 0.028\pm 0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D^+ and D^0 have consistent shapes.Comment: 6 pages postscript,also available through this http://www.lns.cornell.edu/public/CLNS/2006

A Study of the Decays D^0 --> pi^- e^+ nu_e, D^0 --> K^- e^+ nu_e, D^+ --> pi^0 e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

Using 1.8 million DDbar pairs and a neutrino reconstruction technique, we have studied the decays D^0 -> K^- e^+ nu_e, D^0 -> pi^- e^+ nu_e, D^+ -> Kbar^0 e^+ nu_e, and D^+ -> pi^0 e^+ nu_e. We find B(D^0 -> pi^- e^+ nu_e) = 0.299(11)(9)%, B(D^+ -> pi^0 e^+ nu_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%. In addition, form factors are studied through fits to the partial branching fractions obtained in five q^2 ranges. By combining our results with recent unquenched lattice calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106).Comment: 9 pages, postscript also available through http://www.lns.cornell.edu/public/CLNS/2006/, submitted to PR

Search for psi(2S)--> eta_c pi^+ pi^- pi^0

Using 5.63 pb^-1 of data accumulated at the psi(2S) resonance with the CLEO III and CLEO-c detectors corresponding to 3.08 million psi(2S) decays, a search is performed for the decay psi(2S) -> eta_c pi^+pi^-pi^0 to test a theoretical prediction based upon the assumption that the c \bar c pair in the psi(2S) does not annihilate directly into three gluons but rather survives before annihilating. No signal is observed, and a combined upper limit from six eta_c decay modes is determined to be B(psi(2S) -> eta_c pi^+pi^-pi^0) < 1.0 x 10^-3 at 90% C.L. This upper limit is about an order of magnitude below the theoretical expectation.Comment: 8 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006

A Study of the Semileptonic Charm Decays D^0 --> pi^- e^+ nu_e, D^+ --> pi^0 e^+ nu_e, D^0 --> K^- e^+ nu_e, and D^+ --> barK^0 e^+ nu_e

Using a sample of 1.8 million DDbar meson pairs collected at the psi(3770) with the CLEO-c detector, we study the semileptonic decays D^0 -> pi^- e^+ nu_e, D^+ -> pi^0 e^+ \nu_e, D^0 -> K^- e^+ \nu_e, and D^+ -> Kbar^0 e^+ nu_e. For the total branching fractions we find B(D^0 -> pi^- e^+ \nu_e) = 0.299(11)(9)%, B(D^+ -> pi^0 e^+ \nu_e) = 0.373(22)(13)%, B(D^0 -> K^- e^+ nu_e) = 3.56(3)(9)%, and B(D^+ -> Kbar^0 e^+ nu_e) = 8.53(13)(23)%, where the first error is statistical and the second systematic. In addition, form factors are studied through fits to the partial branching fractions obtained in five q^2 ranges. By combining our results with recent unquenched lattice calculations, we obtain |Vcd| = 0.217(9)(4)(23) and |Vcs| = 1.015(10)(11)(106), where the final error is theoretical.Comment: 18 pages, postscript also available through http://www.lns.cornell.edu/public/CLNS/2006/, submitted to PR