The rules of scientific discovery demonstrated from examples of the physics of elementary particles

The rules of scientific discovery as formulated by K. Popper are briefly reviewed. Historical examples such as the prediction of planets and outstanding events in elementary particle physics are used to show how these rules are applied by the working physicist. Thus these rules are shown to be actual tools rather than abstract norms in the development of physics.     

Quantum spring from the Casimir effect

The Casimir effect arises not only in the presence of material boundaries but also in space with nontrivial topology. In this Letter, we choose a topology of the flat (D+1)$(D+1)$-dimensional spacetime, which causes the helix boundary condition for a Hermitian massless scalar field. Especially, Casimir effect for a massless scalar field on the helix boundary condition is investigated in two and three dimensions by using the zeta function techniques. The Casimir force parallel to the axis of the helix behaves very much like the force on a spring that obeys the Hooke's law when the ratio r of the pitch to the circumference of the helix is small, but in this case, the force comes from a quantum effect, so we would like to call it quantum spring. When r is large, this force behaves like the Newton's law of universal gravitation in the leading order. On the other hand, the force perpendicular to the axis decreases monotonously with the increasing of the ratio r. Both forces are attractive and their behaviors are the same in two and three dimensions.     

New constraints on neutrino physics from BOOMERANG data

We have performed a likelihood analysis of the recent data on the cosmic microwave background radiation anisotropy from the BOOMERANG experiment. These data place a strong upper bound on the radiation density present at recombination. Expressed in terms of the equivalent number of neutrino species the 2sigma bound is N(nu)相似文献   

What can low-energy nuclear physics tell us about elementary particles and quarks?

A pedagogic review is presented, for the benefit of the non-particle physicist, of recent remarkable conclusions drawn from the ft values of various superallowed nuclear decays, which are known to great accuracy - such accuracy, in fact, that radiative corrections have to be taken into account to compare the theory with experiment. The calculation of these radiative corrections has recently become possible using the Weinberg-Salam unified gauge theory of weak and electromagnetic interactions as applied to the quark model of elementary particles, and making use of Cabibbo universality, which relates the coupling constants for nuclear decay and muon decay. The good agreement between theory and experiment provides a confirmation of these theoretical models. It is, however, not possible to say whether quarks have integral or fractional charge.     

Casimir effect on quark-gluon plasma

We study the Casimir effect on baryon-free quark-gluon plasma confined in a slab region. The energy and entropy densities of confined QGP at the transition temperature are 2～3 times as large as those of unconfined QGP when the width of the slab is about 1 fm.     

Thermodynamics of the Casimir effect

A complete thermodynamic treatment of the Casimir effect is presented. Explicit expressions for the free and the internal energy, the entropy and the pressure are discussed. As an example we consider the Casimir effect with different temperatures between the plates (T) resp. outside of them (T'). For T'<T the pressure of heat radiation can eventually compensate the Casimir force and the total pressure can vanish. We consider both an isothermal and an adiabatic treatment of the interior region. The equilibrium point (vanishing pressure) turns out instable in the isothermal case. In the adiabatic situation we have both an instable and a stable equilibrium point, if T'/T is sufficiently small. Quantitative aspects are briefly discussed. Received 24 February 1999 and Received in final form 26 April 1999     

Critical exponents and elementary particles

Particles are shown to exist for a.e. value of the mass in single phase ⁴ lattice and continuum field theories and nearest neighbor Ising models. The particles occur in the form of poles at imaginary (Minkowski) momenta of the Fourier transformed two point function. The new inequalitydm ²/dZ, where =m ₀ ² is a bare mass² andZ is the strength of the particle pole, is basic to our method. This inequality implies inequalities for critical exponents.Supported in part by the National Science Foundation under grant PHY 76-17191Supported in part by the National Science Foundation under grant MPS 75-21212     

Constraints on light particles from kaon decays

It is shown how auxiliary field tadpoles may be used to calculate the effective potential in SUSY gauge theories. SUSY QED and SUSY QCD are given as examples.     

Constraints on light particles from stellar evolution

We examine the constraints imposed on the numbers and interactions of light particles by our understanding of the late stages of stellar evolution, including red giants, carbon-burning stars and cooling neutron stars. We show that these astrophysical considerations restrict the number of neutrino types to be less than 10^+2±1. This result complements the standard constraints from cosmological nucleosynthesis, which was unable to exclude numbers of neutrinos between a few thousand and the best particle physics limit of order 10⁵. We also investigate the constraints on supersymmetric theories with a light photino and gravitino, finding that the supersymmetry breaking scale parameter f>O(100GeV) and the selectron masses are >20 to 40 GeV. Finally, we study energy-loss rates by majoron and invisible axion emission.     

Experimental constraints from flavour changing processes and physics beyond the Standard Model

Flavour physics has a long tradition of paving the way for direct discoveries of new particles and interactions. Results over the last decade have placed stringent bounds on the parameter space of physics beyond the Standard Model. Early results from the LHC, and its dedicated flavour factory LHCb, have further tightened these constraints and reiterate the ongoing relevance of flavour studies. The experimental status of flavour observables in the charm and beauty sectors is reviewed in measurements of CP violation, neutral meson mixing, and measurements of rare decays.     

Casimir effect and geometric optics

We propose a new approach to the Casimir effect based on classical ray optics. We define and compute the contribution of classical optical paths to the Casimir force between rigid bodies. We reproduce the standard result for parallel plates and agree over a wide range of parameters with a recent numerical treatment of the sphere and plate with Dirichlet boundary conditions. Our approach improves upon the proximity force approximation. It can be generalized easily to other geometries, other boundary conditions, to the computation of Casimir energy densities, and to many other situations.     

Experiment and theory in the Casimir effect

Casimir effect is the attractive force which acts between two plane parallel, closely spaced, uncharged, metallic plates in vacuum. This phenomenon was predicted theoretically in 1948 and reliably investigated experimentally only in recent years. In fact, the Casimir force is similar to the familiar van der Waals force in the case of relatively large separations when the relativistic effects come into play. We review the most important experiments on measuring the Casimir force by means of torsion pendulum, atomic force microscope and micromechanical torsional oscillator. Special attention is paid to the puzzle of the thermal Casimir force, i.e. to the apparent violation of the third law of thermodynamics when the Lifshitz theory of dispersion forces is applied to real metals. Thereafter we discuss the role of the Casimir force in nanosystems including the stiction phenomenon, actuators, and interaction of hydrogen atoms with carbon nanotubes. The applications of the Casimir effect for constraining predictions of extra-dimensional unification schemes and other physics beyond the standard model are also considered.     

Spectrum of the Casimir effect on a torus

We define a CP violating Dalitz plot asymmetry α_as and compare it to the usual CP violating rate asymmetry α_sy. Depending on the decay mechanisms, α_as can be larger than α_sy. We calculate α_as, α_sy for different models for the decay \(B \to \pi p\bar p\) , using the final state interaction ofp, \(\bar p\) , π to provide the necessary strong interaction interference phase. The values for α_as, α_sy we find vary between 0.01 and 0.4%.     

Casimir效应的另一种计算方法

利用Poisson求和公式和简单的正规化手续,给出了Casimir效应的另一种计算方法.