6370547
Symmetries Shared by Particle Physics and Quantum Optics
It is known that two coupled harmonic oscillators can support the symmetry group as rich as O(3,3) which corresponds to the Lorentz group applicable to three space-like and three time-like coordinates. This group contains many subgroups, including O(3), O(3,2), O(2,1) which are already familiar to us. In this report, we discuss the symmetry of O(1,1) which plays pivotal roles in quantum optics and particle physics. For this one-parameter group, a full-fledged group theory is not necessary, and we can start the discussion from the Hamiltonian of the coupled oscillator system. It is shown first that, from the group theoretical point of view, the squeeze state of light is a representation of this O(1,1) group. It is then shown that the same mathematical device supports three seemingly different ideas of Feynman, namely the parton model, the relativistic quark model for hadrons, and the ``rest of the universe'' in connection with the density matrix. If these three theories are combined, they produce a covariant picture of Feynman's parton model with a built-in decoherence mechanism.
668406
Quantization of electromagnetic fields in a circular cylindrical cavity
We present a quantization procedure for the electromagnetic field in a circular cylindrical cavity with perfectly conducting walls, which is based on the decomposition of the field. A new decomposition procedure is proposed; all vector mode functions satisfying the boundary conditions are obtained with the help of this decomposition. After expanding the quantized field in terms of the vector mode functions, it is possible to derive the Hamiltonian for this quantized system.
73571003
Time separation as a hidden variable to the Copenhagen school of quantum mechanics
The Bohr radius is a space‐like separation between the proton and electron in the hydrogen atom. According to the Copenhagen school of quantum mechanics, the proton is sitting in the absolute Lorentz frame. If this hydrogen atom is observed from a different Lorentz frame, there is a time‐like separation linearly mixed with the Bohr radius. Indeed, the time‐separation is one of the essential variables in high‐energy hadronic physics where the hadron is a bound state of the quarks, while thoroughly hidden in the present form of quantum mechanics. It will be concluded that this variable is hidden in Feynman’s rest of the universe. It is noted first that Feynman’s Lorentz‐invariant differential equation for the bound‐state quarks has a set of solutions which describe all essential features of hadronic physics. These solutions explicitly depend on the time separation between the quarks. This set also forms the mathematical basis for two‐mode squeezed states in quantum optics, where both photons are observable,...
1320799
Wigner rotations and Iwasawa decompositions in polarization optics.
Wigner rotations and Iwasawa decompositions are manifestations of the internal space-time symmetries of massive and massless particles, respectively. It is shown to be possible to produce combinations of optical filters which exhibit transformations corresponding to Wigner rotations and Iwasawa decompositions. This is possible because the combined effects of rotation, phase-shift, and attenuation filters lead to transformation matrices of the six-parameter Lorentz group applicable to Jones vectors and Stokes parameters for polarized light waves. The symmetry transformations in special relativity lead to a set of experiments which can be performed in optics laboratories.
14939249
Coupled Harmonic Oscillators and Feynman's Rest of the Universe
According to Feynman, the universe consists of two parts - the system in which we are interested and the rest of the universe which our measurement process does not reach. Feynman then formulates the density matrix in terms of the observable world and the rest of the universe. It is shown that coupled harmonic oscillators can serve as an illustrative example for Feynman's ``rest of the universe.'' It is pointed out that this simple example has far-reaching consequences in many branches of physics, including statistical mechanics, measurement theory, information theory, thermo-field dynamics, quantum optics, and relativistic quantum mechanics. It is shown that our ignorance of the rest of the universe increases the uncertainty and entropy in the system in which we are interested.
1673726
Symmetries Shared by the Poincaré Group and the Poincaré Sphere
Henri Poincare formulated the mathematics of Lorentz transformations, known as the Poincare group. He also formulated the Poincare sphere for polarization optics. It is shown that these two mathematical instruments can be derived from the two-by-two representations of the Lorentz group. Wigner’s little groups for internal space-time symmetries are studied in detail. While the particle mass is a Lorentz-invariant quantity, it is shown to be possible to address its variations in terms of the decoherence mechanism in polarization optics.
18963275
Heavy quarkonium in a holographic QCD model
Encouraged by recent developments in AdS/QCD models for the light quark system, we study heavy quarkonium in the framework of the AdS/QCD models. We calculate the masses of cc vector meson states using the AdS/QCD models at zero and at finite temperature. Among the models adopted in this work, we find that the soft-wall model describes the low-lying heavy quark meson states at zero temperature relatively well. At finite temperature, we observe that once the bound state is above T{sub c}, its mass will increase with temperature until it dissociates at a temperature of around 494 MeV. It is shown that the dissociation temperature is fixed by the infrared cutoff of the models. The present model serves as a unified nonperturbative model to investigate the properties of bound quarkonium states above T{sub c}.
2251108
Competition Between Induced Symmetry Breaking, Cooper Pairing and Chiral Condensate at Finite Density
We study the competition between induced symmetry breaking (ISB), 
Cooper pairing (superconductivity) and chiral condensation at finite non-asymptotic density. Using a quantum mechanical model studied recently by Ilieva and Thirring, we analyze the expectation value of the fermion number density $\la a^*a\ra$ in the presence of chemical potential and discuss relevance of the ISB phenomenon in the model. By Bogoliubov transformation, we obtain the ground state energy and find that a phase with both superconducting and mean field gap is a true ground state. We also study the effective potentials of a two-dimensional field theory model for competitions between $\la\bar\psi\psi\ra$, $\la\psi\psi\ra$ and $\la\psi^\dagger\psi\ra$. We find that in the regime $\mu \mu_c$ the system sits in the mixed phase characterized by 
$\la \psi^\dagger\psi\ra\neq 0$ and $\la \psi\psi\ra\neq 0$ as long as the renormalization point, $M_0$, corresponding to a superconducting gap is not zero, $M_0\neq 0$.
18064237
The effect of kaon condensation on quark-antiquark condensate in dense matter
Abstract Assuming that at sufficiently high densities the constituent quarks become relevant degrees of freedom, we study within the framework of a chiral quark model the influence of s -wave K − condensation on the quark–antiquark condensates. We find that, in linear density approximation, the presence of a K − condensate quenches the u ¯ u condensate, but that the d ¯ d condensate remains unaffected up to the chiral order under consideration. We discuss the implication of the suppressed u ¯ u condensate for flavor-dependent chiral symmetry restoration in dense matter.
54512122
Bunch length beating in PLS storage ring
During the normal operation period in the Pohang Light Source (PLS) storage ring, the spontaneous bunch length oscillation or beating is generated by the nonlinear effects of the RF noise whose frequency is much lower than the bifurcation frequency. Due to the bunch length beating, we can not supply the uniform intensity beams to users. We have described the observed bunch length beating and its mechanism in the PLS storage ring with a simulation.
117351482
Bubble chamber study of (10÷100) GeV cosmic-ray muons at all zenith angles
SummaryCosmic-ray muons have been studied by analysis of tracks recorded in a large high-field heavy-liquid bubble chamber. From a sample of 50 000 pictures approximately 2 000 muons with energies above 10 GeV were examined for energy and zenith-angle distributions over the complete range from 0° to 90°. In the vertical direction the integral spectrum up to energies exceeding 100 GeV is consistent with depth intensity data and somewhat higher than observed in unshielded vertical magnetic spectrometers. At other zenith angles we find the expected variations, which approach a cos2ϑ attenuation for muons in the 10 GeV region, and tend towards a secϑ enhancement for muon energies above 100 GeV.RiassuntoSi sono studiati i muoni dei raggi cosmici analizzando le tracce fotografate in una grande camera a bolle a liquido pesante con forte campo magnetico. Da un campione di 50 000 fotogrammi si sono esaminati approssimativamente 2 000 muoni con energie superiori a 10 GeV per le distribuzioni di energia e dell’angolo zenitale nell’intero intervallo da 0° a 90°. Nella direzione verticale lo spettro integrale fino ad energie superiori ai 100 GeV è coerente con i dati sull’intensità in profondità ed è leggermente superiore a quello osservato in spettrometri magnetici verticali non schermati. Ad altri angoli zenitali si trovano le variazioni previste, che approssimano una attenuazione del tipo cos2ϑ per muoni nella regione di 10 GeV, e tendono verso un incremento del tipo secϑ per energie dei muoni al di sopra dei 100 GeV.РеэюмеБыли исследованы мюоны в космических лучах посредством аналиэа треков, эарегистрированных в пуэырьковой камере с тяжелой жидкостью, помешенной в сильном поле. Иэ выборки 50000 снимков были исследованы приблиэительно 2000 мюонов с знергиями около 10 ГзВ для получения знергетических распределений и распределений по эенитному углу во всей области углов от 0° до 90°. В вертикальном направлении интегральный спектр вплоть до знергий, превыщаюших 100 ГзВ, согласуется с данными глубинной интенсивности и до некоторой степени выще, чем наблюденный в незкранированных вертикальных магнитных спектрометрах. При других эенитных углах мы обнаружили предполагаемые иэменения, которые почти похожи на ослабление соs2 ϑ для мюонов в области 10 ГзВ и стремятся к увеличению вес ϑ для знергий мюонов выще 100 ГзВ.