http://www.physmathcentral.com/pmcphysa/ The latest research articles published by PMC Physics A 2010-02-19T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Stochastic backgrounds or relic gravitons, if ever detected, will constitute a prima facie evidence of physical processes taking place during the earliest stages of the evolution of the plasma. The essentials of the stochastic backgrounds of relic gravitons are hereby introduced and reviewed. The pivotal observables customarily employed to infer the properties of the relic gravitons are discussed both in the framework of the ΛCDM paradigm as well as in neighboring contexts. The complementarity between experiments measuring the polarization of the Cosmic Microwave Background (such as, for instance, WMAP, Capmap, Quad, Cbi, just to mention a few) and wide band interferometers (e.g. Virgo, Ligo, Geo, Tama) is emphasized. While the analysis of the microwave sky strongly constrains the low-frequency tail of the relic graviton spectrum, wide-band detectors are sensitive to much higher frequencies where the spectral energy density depends chiefly upon the (poorly known) rate of post-inflationary expansion.PACS codes: 04.30.-w, 14.70.Kv, 04.80.Nn, 98.80.-k http://www.physmathcentral.com/1754-0410/4/1 Massimo Giovannini PMC Physics A 2010, 4:1 2010-02-19T00:00:00Z ${item.identifier} PMC Physics A 1754-0410 4 1 2010-02-19T00:00:00Z PDF We combine all the available experimental information on Bs mixing, including the very recent tagged analyses of Bs → J/Ψϕ by the CDF and DØ collaborations. We find that the phase of the Bs mixing amplitude deviates more than 3σ from the Standard Model prediction. While no single measurement has a 3σ significance yet, all the constraints show a remarkable agreement with the combined result. This is a first evidence of physics beyond the Standard Model. This result disfavours New Physics models with Minimal Flavour Violation with the same significance.PACS Codes: 12.15.Ff, 12.15.Hh, 14.40.Nb http://www.physmathcentral.com/1754-0410/3/6 Marcella Bona Marco Ciuchini Enrico Franco Vittorio Lubicz Guido Martinelli Fabrizio Parodi Maurizio Pierini Carlo Schiavi Luca Silvestrini Viola Sordini Achille Stocchi Vincenzo Vagnoni PMC Physics A 2009, 3:6 2009-12-18T00:00:00Z doi:10.1186/1754-0410-3-6 PMC Physics A 1754-0410 3 6 2009-12-18T00:00:00Z XML The quantum cosmological version of a nonsingular Universe presented by Mukhanov and Brandenberger in the early nineties has been developed and the Hamilton Jacobi equation has been found under semiclassical (WKB) approximation. It has been pointed out that, parameterization of classical trajectories with semiclassical time parameter, for such a classically constrained system, is a nontrivial task and requires Lagrangian formulation rather than the Hamiltonian formalism.PACS Codes: 98.80.Qc, 04.50.Kd. http://www.physmathcentral.com/1754-0410/3/5 Abhik Kumar Sanyal PMC Physics A 2009, 3:5 2009-10-22T00:00:00Z doi:10.1186/1754-0410-3-5 PMC Physics A 1754-0410 3 5 2009-10-22T00:00:00Z XML This summary of the Workshop "Beyond the 3-generation SM in the LHC era" presents a brief discussion of the following four statements about the fourth generation: 1) It is not excluded by EW precision data; 2) It addresses some of the currently open questions; 3) It can accommodate emerging possible hints of new physics; 4) LHC has the potential to discover or fully exclude it.PACS codes: 12.60.-i; 14.60. Hi; 14.80.-j http://www.physmathcentral.com/1754-0410/3/4 Bob Holdom W. Hou Tobias Hurth Michelangelo Mangano Saleh Sultansoy Gokhan Unel PMC Physics A 2009, 3:4 2009-09-28T00:00:00Z doi:10.1186/1754-0410-3-4 PMC Physics A 1754-0410 3 4 2009-09-28T00:00:00Z XML We discuss the most important Physics thus far extracted from studies of B meson decays. Measurements of the four CP violating angles accessible in B decay are reviewed as well as direct CP violation. A detailed discussion of the measurements of the CKM elements Vcb and Vub from semileptonic decays is given, and the differences between resulting values using inclusive decays versus exclusive decays is discussed. Measurements of "rare" decays are also reviewed. We point out where CP violating and rare decays could lead to observations of physics beyond that of the Standard Model in future experiments. If such physics is found by directly observation of new particles, e.g. in LHC experiments, B decays can play a decisive role in interpreting the nature of these particles.PACS Codes: 13.25.Hw, 14.40.Nd, 14.65.Fy http://www.physmathcentral.com/1754-0410/3/3 Marina Artuso Elisabetta Barberio Sheldon Stone PMC Physics A 2009, 3:3 2009-02-20T00:00:00Z doi:10.1186/1754-0410-3-3 PMC Physics A 1754-0410 3 3 2009-02-20T00:00:00Z XML In this paper, the Feynman path integral formulation of the continuous-continuous filtering problem, a fundamental problem of applied science, is investigated for the case when the noise in the signal and measurement model is Gaussian and additive. It is shown that it leads to an independent and self-contained analysis and solution of the problem. A consequence of this analysis is the configuration space Feynman path integral formula for the conditional probability density that manifests the underlying physics of the problem. A corollary of the path integral formula is the Yau algorithm that has been shown to have excellent numerical properties. The Feynman path integral formulation is shown to lead to practical and implementable algorithms. In particular, the solution of the Yau partial differential equation is reduced to one of function computation and integration.PACS Codes: 02.50.Ey, 02.50.Fz, 05.10.Gg, 89.90.+n, 93E10, 93E11 http://www.physmathcentral.com/1754-0410/3/2 Bhashyam Balaji PMC Physics A 2009, 3:2 2009-02-10T00:00:00Z doi:10.1186/1754-0410-3-2 PMC Physics A 1754-0410 3 2 2009-02-10T00:00:00Z XML The generalized Weinberg sum rules containing the difference of isovector vector and axial-vector spectral functions saturated by both finite and infinite number of narrow resonances are considered. We give a historical survey and summarize the status of these sum rules analyzing their overall agreement with phenomenological Lagrangians, low-energy relations, parity doubling, hadron string models, and experimental data.PACS codes: 11.55.Hx, 11.30.Rd http://www.physmathcentral.com/1754-0410/3/1 Sergey Afonin PMC Physics A 2009, 3:1 2009-01-08T00:00:00Z doi:10.1186/1754-0410-3-1 PMC Physics A 1754-0410 3 1 2009-01-08T00:00:00Z XML Results are presented from a study of the structure of hadronic events in high-energy e+e- interactions detected by the L3 detector at LEP. Various event shape distributions and their moments are measured at several energy points at and above the Z-boson mass. The event flavour is tagged by using the decay characteristics of b-hadrons. Measurements of distributions of event shape variables for all hadronic events, for light (u, d, s, c) and heavy (b) quark flavours are compared to several QCD models with improved leading log approximation: JETSET, HERWIG and ARIADNE. A good description of the data is provided by the models.PACS Codes: 12.38.Qk, 13.66.Bc http://www.physmathcentral.com/1754-0410/2/6 L3 Collaboration PMC Physics A 2008, 2:6 2008-12-08T00:00:00Z doi:10.1186/1754-0410-2-6 PMC Physics A 1754-0410 2 6 2008-12-08T00:00:00Z XML A plasma focus device capable of operating at 0.2 pulses per second during several minutes is used as a source of hard x-rays and fast neutrons. An experimental demonstration of the use of the neutrons emissions for radiation probing of hydrogenated substances is presented, showing a particular application in detecting water concentrations differences in the proximity of the device by elastic scattering. Moreover, the device produces ultrashort hard x-rays pulses useful for introspective images of small objects, static or in fast motion, suitable for the identification of internal submillimetric defects. Clear images of metallic objects shielded by several millimeters iron walls are shown.PACS Codes: 29.25.Dz,52.59.Px http://www.physmathcentral.com/1754-0410/2/5 V. Raspa F. Di Lorenzo P. Knoblauch A. Lazarte A. Tartaglione A. Clausse C. Moreno PMC Physics A 2008, 2:5 2008-10-29T00:00:00Z doi:10.1186/1754-0410-2-5 PMC Physics A 1754-0410 2 5 2008-10-29T00:00:00Z XML On Wednesday September 10th 2008, physicists and engineers at the CERN laboratory which straddles the Swiss-French border near Geneva began the commissioning of the Large Hadron Collider (the LHC) with beam, and the four LHC experiments (ATLAS, CMS, LCHb and ALICE) saw their first interactions, albeit between the contra-rotating beams of protons and the tiny amounts of residual gas in the beam pipe. Remarkably, these first steps in the ambitious physics programme were taken in the full glare of the media spotlight, which was no doubt excited by the speculation that these first collisions might produce a black hole and destroy the Universe as we know it, or at least the part of it that is near and dear to us. http://www.physmathcentral.com/1754-0410/2/4 Ken Peach PMC Physics A 2008, 2:4 2008-09-10T00:00:00Z doi:10.1186/1754-0410-2-4 PMC Physics A 1754-0410 2 4 2008-09-10T00:00:00Z XML