26709728
Radiative B meson decays into kpigamma and kpipigamma final states.
We report observations of radiative B meson decays into the K+pi(-)gamma and K+pi(-)pi(+)gamma final states. In the B0-->K+pi(-)gamma channel, we present evidence for decays via an intermediate tensor meson state with a branching fraction of B(B0-->K(*)(2)(1430)(0)gamma)=[1.3+/-0.5(stat)+/-0.1(syst)]x10(-5). We measure the branching fraction B(B+-->K+pi(-)pi(+)gamma)=[2.4+/-0.5(stat) +0.4-0.2(syst)]x10(-5), in which the B+-->K(*0)pi(+)gamma and B+-->K+rho(0)gamma channels dominate. The analysis is based on a data set of 29.4 fb(-1) recorded by the Belle experiment at the KEKB collider.
125141344
Studies of B0 ---> rho+- pi-+ and evidence of B0 ----> rho0 pi0
3197654
Observation of large CP violation in the neutral B meson system.
We present a measurement of the standard model CP violation parameter sin2 phi(1) based on a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is fully reconstructed as a J/psi K(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psi K(L), or J/psi K(*0) decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2 phi(1) = 0.99+/-0.14(stat)+/-0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.
209833820
Search for leptonic decays of D0 mesons
We search for the flavor-changing neutral current decays D-0 -> mu(+)mu(-) and D-0 -> e(+)e(-), and for the lepton-flavor violating decays D-0 -> e(+/-)mu(-/+) using 660 fb(-1) of data collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We find no evidence for any of these decays. We obtain significantly improved upper limits on the branching fractions: B(D-0 -> mu(+)mu(-)) e(+)e(-)) e(+)mu(-)) + B(D-0 -> mu(+)e(-)) < 2.6 x 10(-7) at 90% confidence level.
123584252
Measurement of branching fractions and charge asymmetries for two-body B meson decays with charmonium
We report branching fractions and charge asymmetries for exclusive decays of charged and neutral B mesons to two-body final states containing a charmonium meson, J/Ψ or Ψ/(2S). This result is based on a 29.4 fb-1 data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric e+e- collider. © 2003 The American Physical Society.
126239408
Observation of B+ ---> K(1)(1270)+ gamma
13432743
Search for lepton-flavor-violating decays of the neutral kaon.
The Fermilab KTeV experiment has searched for lepton-flavor-violating decays of the K(L) meson in three decay modes. We observe no events in the signal region for any of the modes studied, and we set the following upper limits for their branching ratios at the 90% C.L.: BR(K(L) --> pi(0) micro(+/-) e(-/+)) <7.6 x 10(-11); BR(K(L) --> pi(0)pi(0) micro(+/-) e(-/+)) <1.7 x 10(-10); BR(pi(0) --> micro(+/-) e(-/+)) <3.6 x 10(-10). This result represents a factor of 82 improvement in the branching ratio limit for K(L) --> pi(0) micro(+/-) e(-/+) and is the first reported limit for K(L) --> pi(0)pi(0) micro(+/-) e(-/+).
117024221
Intervening BLR Clouds' Effects on Optical/UV Spectrum
Recent x-ray observations of Mrk 766 suggest that broad emission line region clouds cross our line of sight and produce variable x-ray absorption. Here we investigate what optical/ultraviolet spectroscopic features would be produced by such "Intervening BLR Clouds" (IBC) crossing our line of sight to the accretion disk, the source of the optical/UV continuum. Although the emission spectrum produced by intervening clouds is identical to the standard BLR model, they may produce absorption features on the optical or UV continuum. Single clouds will have little effect on the optical/UV spectrum because BLR clouds are likely to be much smaller than the accretion disk. This is unlike the X-ray case, where the radiation source is considerably smaller. However, an ensemble of intervening clouds will produce spectroscopic features in the FUV including a strong depression between the Lyman limit and Ly{\alpha}. The amount of the depression will indicate the line-of-sight covering factor of clouds, an unknown quantity that is important for the ionization of the intergalactic medium and the energy budget of AGN. Comparison with observations suggests that the SED of Mrk 766 may be affected by intervening BLR clouds and IBC may exist in most of AGNs.
18263810
Damped accelerator structures
This paper reports continuing work on high-gradient accelerator structures for future TeV linear colliders. A prerequisite of these structures is that they heavily damp wakefield modes which can be induced by e{sup {plus minus}} bunch trains. Disk-loaded waveguide structures under investigation have radial slots in the disks and/or radial rectangular waveguides in the cavity walls to couple wakefield power out to external lossy regions. We discuss a high-power S-Band experiment with a short standing-wave section to determine whether the peak field breakdown threshold is lowered by the presence of slots in the disks. Next, we describe low-power measurements on structure models at S-Band and X-Band to identify mode frequencies and Q values. 3 refs., 11 figs.
8085635
Beam test results of the BTeV silicon pixel detector
We report the main results of the BTeV silicon pixel detector beam test carried out at Fermilab during the fixed target run 1999-2000. The tests were performed using a 227 GeV/c pion beam incident on a 6 plane silicon microstrip telescope. Several single-chip silicon pixel planes were placed in the middle of the apparatus. The pixel detector spatial resolution has been studied as a function of track inclination and the number of ADC bits. The effect of an applied external magnetic field was also studied.
15611957
Determination of the parity of the neutral pion via its four-electron decay.
We present a new determination of the parity of the neutral pion via the double Dalitz decay pi0-->e+e-e+e-. Our sample, which consists of 30,511 candidate decays, was collected from KL-->pi0pi0pi0 decays in flight at the KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the negative pi0 parity and place a limit on scalar contributions to the pi0-->e+e-e+e- decay amplitude of less than 3.3% assuming CPT conservation. The pi0gamma*gamma* form factor is well described by a momentum-dependent model with a slope parameter fit to the final state phase-space distribution. Additionally, we have measured the branching ratio of this mode to be B(pi0-->e+e-e+e-)=(3.26+/-0.18)x10(-5).