Measurement of the Photon Structure Function at High Q 2 at LEP
The structure functions of real and virtual photons are derivedfrom cross section measurements of the reaction$\rm e^+e^-\rightarrow e^+e^- + \hbox{hadrons}$ at LEP.The reaction is studied at $\sqrt{\rm {s}} \simeq 91$ GeV with the L3detector. One of the final state electrons is detected at a large angle relative to the beam direction, leading to $Q^2$ values between40 GeV$^2$ and 500 GeV$^2$.The other final state electron is either undetected or it is detected ata four-momentum transfer squared $P^2$ between 1 GeV$^2$ and 8 GeV$^2$.These measurements are compared with predictions of the Quark PartonModel and other QCD based models.

title: Search for flavor-changing-neutral-current d meson decays.
abstract: We study the flavor-changing-neutral-current process c-->u micro(+) micro(-) using 1.3 fb(-1) of pp[over ] collisions at square root s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated D(s)(+) and D(+)-->phipi(+) --> micro(+)micro(-)pi(+) final states with significance greater than 4 standard deviations above background for the D(+) state. We search for the continuum neutral-current decay of D(+)-->pi(+) micro(+) micro(-) in the dimuon invariant mass spectrum away from the phi resonance. We see no evidence of signal above background and set a limit of B(D(+) --> pi(+) micro(+) micro(-))<3.9 x 10(-6) at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c--> u micro(+) micro(-) transition.

title: Measurement of inclusive differential cross sections for $\upsilon_{1S}$ production in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.96-TeV

title: Measurement of semileptonic branching fractions of B mesons to narrow D** states.
abstract: Using the data accumulated in 2002-2004 with the D0 detector in proton-antiproton collisions at the Fermilab Tevatron collider with a center-of-mass energy of 1.96 TeV, the branching fractions of the decays B --> D0(1)(2420)mu+ vmuX and B --> D2(*0)(2460)mu+ vmuX and their ratio have been measured: B(b --> B) x B(B --> D0(1)mu+ vmuX) x B(D0(*0) --> D*- pi+) = [0.087 +/- 0.007(stat) +/- 0.014(syst)]%; B(b --> B) x B(B --> D2(*0) mu+ vmuX) x B(D2(*0) --> D*- pi+) = [0.035 +/- 0.007(stat) +/- 0.008(syst)]% and [B(B --> D2(*0)mu+ vmuX) x B(D2(*0) --> D*- pi+)]/[B(B --> D0(1)mu+ vmuX) x B(D0(1) --> D*- pi+)] = 0.39 +/- 0.09(stat) +/- 0.12 (syst), where the charge conjugated states are always implied.

title: $t \bar{t}$ production cross-section in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8-TeV
abstract: Results are presented on a measurement of the t (t) over bar pair production cross section in p (p) over bar collisions at roots=1.8 TeV from nine independent decay channels. The data were collected by the D empty set experiment during the 1992-1996 run of the Fermilab Tevatron Collider. A total of 80 candidate events is observed with an expected background of 38.8+/-3.3 events. For a top quark mass of 172.1 GeV/c(2), the measured cross section is 5.69+/-1.21(stat)+/-1.04(syst) pb.

title: Measurement of Inclusive Charm Production in Two -Photon Collisions at LEP.
abstract: The cross section of inclusive charm production in two-photon collisions  e+e_ccX) is measured at the Large Electron Positron (LEP) col­ lider at the European Center for Nuclear and Particle Physics (CERN). The data was obtained with the L3 detector at the center-of-mass energy of 91 GeV (LEP1) and for the first time at the center-of-mass energies from 130183 GeV (LEP2). Charmed hadrons are identified by electrons and muons from semileptonic decays. The measured cross section agrees with ne^t-toleading order (NLO) QCD calculations. The direct process 7 7 —► cc is found to be insufficient to describe the data. The measured cross section values and event distributions require contributions from resolved processes, which are sensitive to the gluon density in the photon.

title: Parity-Time Symmetry Breaking beyond One Dimension: The Role of Degeneracy
abstract: We consider the role of degeneracy in Parity-Time (PT) symmetry breaking for non-hermitian wave equations beyond one dimension. We show that if the spectrum is degenerate in the absence of T-breaking, and T is broken in a generic manner (without preserving other discrete symmetries), then the standard PT-symmetry breaking transition does not occur, meaning that the spectrum is complex even for infinitesimal strength of gain and loss. However the realness of the entire spectrum can be preserved over a finite interval if additional discrete symmetries X are imposed when T is broken, if X decouple all degenerate modes. When this is true only for a subset of the degenerate spectrum, there can be a partial PT transition in which this subset remains real over a finite interval of T-breaking. If the spectrum has odd-degeneracy, a fraction of the degenerate spectrum can remain in the symmetric phase even without imposing additional discrete symmetries, and they are analogous to dark states in atomic physics. These results are illustrated by the example of different T-breaking perturbations of a uniform dielectric disk and sphere, and a group theoretical analysis is given in the disk case. Finally, we show that multimode coupling is capable of restoring the T-symmetric phase at finite T-breaking. We also analyze these questions when the parity operator is replaced by another spatial symmetry operator and find that the behavior can be qualitatively different.

title: Ground‐State Magnetization in Disordered Systems: Exchange versus Off‐Diagonal Interaction Fluctuations