122721907
Into the mix
The challenge to measure the quantum-mechanical mixing between particle and antiparticle states for a particular type of meson is at last being met — but as yet, alas, reveals no exotic physics.
117156652
Properties of Quark and Gluon Jets — a LEP Mini Review
Recent results on the structure of and differences between quark and gluon jets from the four LEP experiments are reviewed.
123293754
Production of charmed hadrons in neutrino proton and antineutrino proton charged current interactions
AbstractUsind data from avp and
$$\bar v$$
p experiment with BEBC at CERN, the rates for inclusive production ofD*+,Λc+ andD0 invp scattering and ofD*− in
$$\bar v$$
p scattering are measured. Some examples of the exclusive production ofD*+,Λc+ and∑c++ are given. The cross section for the reactionvp→μ−c++ is estimated.
122591819
Experimental test of the PCAC-hypothesis in charged current neutrino and antineutrino interactions on protons
Data obtained with the bubble chamber BEBC at CERN are used for the first significant test of Adler's prediction for the neutrino and antineutrino-proton scattering cross sections at vanishing four-momentum transfer squaredQ2. An Extended Vector Meson Dominance Model (EVDM) is applied to extrapolate Adler's prediction to experimentally accessible values ofQ2. The data show good agreement with Adler's prediction forQ2→0 thus confirming the PCAC hypothesis in the kinematical region of high leptonic energy transfer ν>2 GeV. The good agreement of the data with the theoretical predictions also at higherQ2, where the EVDM terms are dominant, also supports this model. However, an EVDM calculation without PCAC is clearly ruled out by the data.
120991534
B-physics in the p-p collisions at the LHC
The LHC provides an excellent opportunity for B-physics studies, providing both high statistics and a wide range of kinematic conditions. This paper summarises the prospects for the ATLAS, CMS and LHCb experiments, with an emphasis on the QCD aspects. The rather different programme of the heavy-ions experiment ALICE is not addressed. The experiments will probe both the production and decay of B-hadrons. The various trigger strategies are presented, after which the production measurements are considersed and are shown to provide stringent test of QCD, as well as providing vital information of the backgrounds to searches. After this, the studies of B-decays are presented. The measurements of CP-violation are shown to have a good potential for discovering signatures of new physics. B s mixing will also open a window on new physics, and Δ| Gamma s will be measurable. Finally, the prospects for rare deacys are considered, especially for the decays to muons.
62239385
The ATLAS computing model
The ATLAS Computing Model was constructed after early tests and was captured in the ATLAS Computing TDR in June 2005. Since then, the grid tools and services have evolved and their performance is starting to be understood through large-scale exercises. As real data taking becomes immanent, the computing model continues to evolve, with robustness and reliability being the watchwords for the early deployment. Particular areas of active development are the data placement and data access, and the interaction between the TAGs, the datasets and the Distributed Data Management issues. The earlier high-level policies and models are now being refined into lower level instantiations.
20354147
Possible Phase Loop for the Global Decoupling
The two eigentunes Q<inf>I</inf>and Q<inf>II</inf>, two eigenmode amplitude ratios R<inf>I</inf>and R<inf>II</inf>, and two eignmode phase differences Δφ<inf>I</inf>and Δφ<inf>II</inf>, are defined as the coupling observables for the linear weak difference betatron coupling. Simulations were carried out to investigate their behaviors in global decoupling scans. It was found that the amplitude ratios R<inf>I</inf>,<inf>II</inf>are more sensitive than the tune split when the decoupling scan is approaching the global uncoupled point, and that the phase differences Δφ<inf>I</inf>,<inf>II</inf>tell the right global decoupling direction, the right strength combination of the skew quadrupoles or families. The analytical solution to these six coupling observables is calculated through both the strict matrix approach and the perturbation Hamiltonian approach. The constant phase differences in the right decoupling direction hint a possible global decoupling phase loop. Dedicated beam experiments were carried out at the Relativistic Heavy Ion Collider (RHIC). The preliminary results from the beam experiments are presented. These six parameters can be used for the global decoupling in feedback mode, especially on the non-stop energy ramp.
17515691
The classical action for a Bianchi VI_h model
An estimate for the classical action for a Bianchi VI_h homogeneous spatially closed cosmology is presented as a function of b, a parameter of the model that is proportional to the relative rotation of the average inertial frame and the bulk of matter in the universe. It is assumed (through the equation of state) that a relativistic early universe is followed by a matter-dominated late universe. The action is used in a saddlepoint approximation to a semiclassical estimate for the wave function in quantum cosmology to explain why our inertial frame seems not to rotate relative to the stars. The saddlepoint is at b=0, as would be expected. Application of the saddlepoint approximation leads to the result that only those classical geometries whose action differs from the saddlepoint value for the action by an amount less than Planck's constant contribute significantly to the integration to give the present value of the wave function. Using estimates for our universe implies that only those classical geometries for which the present relative rotation rate of inertial frames and matter are less than about 10^(-130) radians per year contribute significantly to the integration. This is well below the limit set by experiment. The result depends on the ratio of the Hubble distance to the Planck length, but does not depend on the details of the theory of quantum gravity.