Showing papers in "Progress of Theoretical Physics in 1995"
TL;DR: In this paper, it was shown that the reheating temperature has to be smaller than (10 11 -10 12 ) GeV for the photino mass (10-100) GeV, irrespectively of the gravitino mass.
Abstract: He, 'He) leads to the most stringent upperbound on the reheating temperature, which is given by (10 6 -10 9 ) GeV for the gravitino mass 100 GeV -1 TeV. On the other hand, requiring that the present mass density of photino should be smaller than the critical density, we find that the reheating temperature have to be smaller than (10 11 -10 12 ) GeV for the photino mass (10-100) GeV, irrespectively of the gravitino mass. The effect of other decay channels is also considered.
275 citations
TL;DR: This paper formulated the renormalization group (RG) method for global analysis, recently proposed by Goldenfeld et al., on the basis of the classical theory of envelopes, and clarified why the RG equation improves things.
Abstract: On the basis of the classical theory of envelopes, we formulate the renormalization group (RG) method for global analysis, recently proposed by Goldenfeld et al. It is clarified why the RG equation improves things.
119 citations
TL;DR: In this article, the authors used the Schwarzschild criterion for convection and neglect overshooting to obtain the C(a, 7) 1 6 0 rate Presupernova models for helium stars with masses of Ma = 3.1.
Abstract: 1. Presupernova models and the C(a, 7) 1 6 0 rate Presupernova models are obtained for helium stars with masses of Ma = 3.3, 4, 5, 6, 8, 16, and 32 M© as an extension of the studies by Nomoto & Hashimoto (1988), Thielemann et al. (1993), and Hashimoto et al. (1993). These helium star masses correspond approximately to main-sequence masses of Mm s = 13, 15, 18, 20, 25, 40, and 70 MQ, respectively (Sugimoto & Nomoto 1980). The systematic study for such a dense grid of stellar masses enables us to understand how explosive nucleosynthesis depends on the presupernova stellar structure and to apply the results to the chemical evolution of galaxies. We use the Schwarzschild criterion for convection and neglect overshooting. The initial composition is given by X(He) = 0.9879 and X(N) = 0.0121. These helium stars are evolved from helium burning through the onset of the Fe core collapse. Nuclear reaction rates are mostly taken from Caughlan & Fowler (1988). For the uncertain rate of 1 2 C(a ,7) 1 6 0 , we use the rate by Caughlan et al. (1985; CFHZ85), which is larger than the rate by Caughlan & Fowler (1988; CF88) by a factor of ~ 2.4. To examine the influence of this difference, we evolve the Ma = 8 MQ helium star, using the 1 2 C(a , 7 ) 1 6 0 rate by CF88 (case 25B). [The 25 M 0 star model with the 1 2 C ( Q , 7 ) 1 6 0 rate by CFHZ85 is denoted as case 25A.] At the end of core helium burning, the formation of the carbon-oxygen core and its composition are influenced largely by the 1 2 C(a ,7) 1 6 0 rate. The larger rate results in a smaller C/O ratio, which affects the abundances of Ne, Mg, Al relative to O in the more evolved cores. Comparison of the presupernova density structures for the two cases 25A and 25B shows that case 25B has a more concentrated core at Mr < 2MQ (i.e., a steeper density gradient) and more extended outer layers than case 25A. This is due to a larger carbon abundance and thus stronger carbon shell burning in case 25B. It is found that the size of the iron core is not a monotonic function of the helium core mass as shown by Barkat & Marom (1990) and Woosley (1993). For Mm s = 13, 15, 18, 20, 25 (case 25A), 40, and 70 MQ, the iron core masses are 1.18, 1.28, 1.36, 1.40, 1.42, 1.88, and 1.57 M 0 , respectively. In case 25B, the iron core mass is 1.37 MQ, which is smaller than in case 25A.
96 citations
TL;DR: In this article, the behavior of quantum field and quantum ground state when the field is coupled to perturbation that periodically oscillates is investigated, and the energy spectrum and the intensity of produced particles are worked out in greatest detail in the limit of weak coupling or small amplitude perturbations.
Abstract: We develop a formalism to investigate the behavior of quantum field and quantum ground state when the field is coupled to perturbation that periodically oscillates. Working in the Schroedinger picture of quantum field theory, we confirm that the phenomenon of parametric resonance in the classical theory implies an instability of quantum vacuum, and correspondingly it gives rise to catastrophic particle production if the oscillation lasts indefinitely; the produced number of particles exponentially increases without bound as time proceeds. The density matrix describing the limiting stage of the quantum state is determined by a small set of parameters. Moreover, the energy spectrum and the intensity of produced particles are worked out in greatest detail in the limit of weak coupling or small amplitude perturbation. In the case of strong coupling or large amplitude perturbation the leading adiabatic formula is derived. Application to cosmological fate of weakly interacting spinless fields (WISF) such as the invisible axion, the Polonyi, and the modular fields is discussed. Although very little effect is expected on the invisible axion, the Polonyi type field has a chance that it catastrophically decays at an early epoch without much production of entropy, provided that an intrinsic coupling is large enough.
76 citations
61 citations
TL;DR: In this article, the angular momentum projection is applied to these rotating intrinsic states in order to get good angular momentum states, which enables us to describe the dissolution of clusters more satisfactorily, and the two-cluster structure of "'O+a results as a predominant configuration and that the'6 0 +a clustering becomes weaker as the spin goes up and mixes with the spin-aligned oblate structure when going from 6+ to s+.
Abstract: 20 Ne is studied with the Antisymmetrized Molecular Dynamics which is a method free from any model assumption such as the existence of clustering. The construction of the rotating intrinsic states is made by the frictional cooling method under the constraint that the expectation value of the angular momentum vector takes the given value in its magnitude while its direction is determined variationally. Angular momentum projection is applied to these rotating intrinsic states in order to get good angular momentum states. Two· body spin-orbit force is adopted and nucleon spin orientations expressed by spin coherent states are determined by energy variation, which enables us to describe the dissolution of clusters more satisfactorily. It is found that for both positive and negative parity low spin states, the two-cluster structure of "'O+a results as a predominant configuration and that the ' 6 0 +a clustering becomes weaker as the spin goes up and mixes with the spin-aligned oblate structure when going from 6+ to s+. The yrast states with 10+, 12+ and n- are found to have the three-cluster-like structure composed of 12 C cluster and two a clusters.
56 citations
TL;DR: In this article, the binding energy and excited states of the 4 He + n + n+ n three-body system were investigated by using the hybrid-TV model of the four He-n interaction.
Abstract: By using the hybrid- TV model of the 4 He + n + n three-body system, the binding energy and excited states of "He are investigated. The binding energy 0.784 MeV is obtained for more realistic 4 He-n interaction. It is discussed that the n-n correlations, which are fully taken into account in the ECM bases, are very important to reproduce the binding energy of "He. The excited resonance states of the "He system are also calculated by applying the complex scaling method. The first excited z+ state obtained as a three-body resonance state is in good agreement with experiments. However, the excited 1- resonance states corresponding to the soft dipole excitation are not obtained at the low energy region.
56 citations
TL;DR: In this article, the two-loop long range effect on the proton decay effective Lagrangian was calculated and the suppression factor was shown to be 0.321 for the value of the strong coupling constant.
Abstract: We calculate the two loop long range effect on the proton decay effective Lagrangian. Numerical calculation for suppression factor gives $ A_L($2-loop$) = 0.321$ for the value of the strong coupling constant $ \alpha_s(m_Z) = 0.116 $. Two loop effect to more general effective Lagrangian is also given.
54 citations
TL;DR: In this article, the role of monopoles in the deconfinement transition is discussed in the framework of abelian projection in the maximally abelians gauge in T=I=O SU(2) QCD.
Abstract: The role of monopoles in the deconfinement transition is discussed in the framework of abelian projection in the maximally abelian gauge in T=I=O SU(2) QCD. Only one (or a few near flc) long connected monopole loop exists uniformly through the whole lattice in each vacuum configuration in addition to some very short loops in the confinement phase and the long loop disappears in the deep deconfinement region. Energy·entropy balance of the long loops of maximally extended monopoles explains the existence of the deconfinement transition and reproduces roughly the value of the critical temperature.
42 citations
40 citations
TL;DR: In this paper, the dynamical chiral symmetry breaking of nonperturbative QCD was investigated in the dual Ginzburg-Landau theory, where the QCD-monopole field is introduced as an essential field for color confinement stemming from the choice of the abelian gauge fixing a!a 't Hooft.
Abstract: We study dynamical chiral-symmetry breaking of non-perturbative QCD in the dual Ginzburg Landau theory, where the QCD-monopole field is introduced as an essential field for color confinement stemming from the choice of the abelian gauge fixing a !a 't Hooft. In this theory, QCD-monopole condensation causes the dual Meissner effect, which changes the gluon propagator. The dynamical chiral-symmetry breaking is investigated using the Schwinger-Dyson equation with the modified gluon propagator in the QCD-monopole condensed vacuum. We introduce the low momentum cutoff on the modified gluon propagator by considering the effects of the q- q pair creation and/or the quarks being confined in hadrons. We find that dynamical chiral-symmetry breaking is largely enhanced by QCD-monopole condensation, which suggests the close relation between the color confinement and the chiral symmetry breaking. The dynamical quark mass, the pion decay constant and the quark condensate are reproduced consistently with the confining mechanism in this theory.
TL;DR: In this article, the asymptotic behavior of the orbits in the vicinity of the networks of heteroclinic orbits is analyzed using an approximation, and the existence of a new type of game dynamics system is discovered.
Abstract: The asymptotic behavior of the orbits in the vicinity of the networks of heteroclinic orbits is analyzed using an approximation. As a result of the analysis, the existence of a new type of asymptotic behavior in a game dynamics system is discovered. The feature of this asymptotic behavior is a combination of the chaotic motion and the attraction to a heteroclinic cycle; the trajectory visits several unstable stationary states repeatedly with an irregular order, and the typical length of stays near the steady states grows roughly exponentially with the number of visits. The dynamics underlying this irregular motion is related to the low·dimensional chaotic dynamics. The relation of this irregular motion with a peculiar type of instability of heteroclinic cycle attractors is also examined.
TL;DR: In this paper, the authors reformulate the Thirring model in (2 + 1) dimensions as a gauge theory by introducing hidden local symmetry (HLS) and study the dynamical mass generation of the fermion through the Schwinger-Dyson (SD) equation.
Abstract: We reformulate the Thirring model in $D$ $(2 \le D < 4)$ dimensions as a gauge theory by introducing $U(1)$ hidden local symmetry (HLS) and study the dynamical mass generation of the fermion through the Schwinger-Dyson (SD) equation. By virtue of such a gauge symmetry we can greatly simplify the analysis of the SD equation by taking the most appropriate gauge (``nonlocal gauge'') for the HLS.
In the case of even-number of (2-component) fermions, we find the dynamical fermion mass generation as the second order phase transition at certain fermion number, which breaks the chiral symmetry but preserves the parity in (2+1) dimensions ($D=3$). In the infinite four-fermion coupling (massless gauge boson) limit in (2+1) dimensions, the result coincides with that of the (2+1)-dimensional QED, with the critical number of the 4-component fermion being $N_{\rm cr} = \frac{128}{3\pi^{2}}$. As to the case of odd-number (2-component) fermion in (2+1) dimensions, the regularization ambiguity on the induced Chern-Simons term may be resolved by specifying the regularization so as to preserve the HLS.
Our method also applies to the (1+1) dimensions, the result being consistent with the exact solution. The bosonization mechanism in (1+1) dimensional Thirring model is also reproduced in the context of dual-transformed theory for the HLS.
TL;DR: In this article, the SUs properties of two-baryon systems are extensively incorporated with the explicit flavor symmetry breaking of the full Fermi-Breit residual interaction.
Abstract: Characteristic properties of the medium·range central attraction of the nucleon·nucleon and hyperon-nucleon interactions are studied in the (3q)-(3q) resonating-group formulation. The SUs properties of two-baryon systems are extensively incorporated with the explicit flavor symmetry breaking of the full Fermi-Breit residual interaction. It is found that, for a realistic quark-model description of the hyperon-nucleon interaction compatible with the present low-energy experimental data, it is necessary to introduce phenomenological medium-range attraction which is much less than that for the nucleon-nucleon system. Effective meson-exchange potentials from the scalar-meson nonet exchange in the Nijmegen model-F are conveniently employed to generate the needed flavor dependent central attraction with few parameters determined for each flavor exchange symmetry.
TL;DR: In this article, the determinant of a gauge boson or fermion field in a fixed "small" external gauge field is derived in terms of explicitly gauge invariant quantities, and again may be regularized by cutoff regularization.
Abstract: The Euclidean version of the Yang-Mills theory is studied in four dimensions. The field is expressed non-linearly in terms of the basic variables. The field is developed inductively, adding one excitation at a time. A given excitation is added into the "background field" of the excitations already added, the background field expressed in a radially axial gauge about the point where the excitation is centered. The linearization of the resultant expression for the field is an expansion Ap(x)~I:ca¢p•(x), a where ¢P•(x) is a divergence-free wavelet and c. is the associated basic variable, a Lie Algebra element of the gauge group. One is working in a particular gauge, regularization is simply cutoff regularization realized by omitting wavelet excitations below a certain length scale. We will prove in a later paper that only the usual gauge-invariant counterterms are required to renormalize perturbation theory. Using related ideas, but essentially independent of the rest of the paper, we find an expression for the determinant of a gauged boson or fermion field in a fixed "small" external gauge field. This determinant is expressed in terms of explicitly gauge invariant quantities, and again may be regular· ized by a cutoff regularization. We leave to later work relating these regularizations to the usual dimensional regularization.
TL;DR: In this paper, the authors study four-dimensional simplicial gravity through numerical simulation with special attention to the existence of singular vertices, in the strong coupling phase, that are shared by abnormally large numbers of four-simplices.
Abstract: We study four--dimensional simplicial gravity through numerical simulation with special attention to the existence of singular vertices, in the strong coupling phase, that are shared by abnormally large numbers of four--simplices The second order phase transition from the strong coupling phase into the weak coupling phase could be understood as the disappearance of the singular vertices We also change the topology of the universe from the sphere to the torus
TL;DR: In this paper, the authors studied the mass constraint on the mass of the charged Higgs boson in the minimal supergravity model based on the recent measurement of the inclusive b−sr decay.
Abstract: We study the constraint on the mass of the charged Higgs boson in the minimal supergravity model based on the recent measurement of the inclusive b~sr decay It is shown that the lower bound for the charged Higgs mass crucially depends on the sign of the higgsino mass parameter (f-1) For 1-1 O due to cancellations between charged Higgs and supersymmetric particle contributions For 3:StanP:S5, a charged Higgs lighter than 180 GeV is excluded by this process irrespective of the sign of f-1 407 Flavor changing neutral current (FCNC) processes play a unique role in search ing for physics beyond the standard model (SM) of elementary particles These processes are sensitive to virtual effects of new particles, since the FCNC processes in SM do not occur at the three level These processes can thus be more powerful than direct particle searches in putting constraints on the parameter space of various new physics In particular, the radiative decay of the b quark, b-+sr, deserves special attention It has been noticed that in a two Higgs doublet model (THDM) the charged Higgs boson can give a substantial contribution to the b-+ sr rate 0 • 2 >
TL;DR: A unified description of the hyperon-nucleon interaction consistent with the NN interaction is given in the RGM formulation of the SUs quark model, in which the full Fermi-Breit interaction with explicit flavor symmetry breaking is incorporated as discussed by the authors.
Abstract: A unified description of the hyperon-nucleon interaction consistent with the NN interaction is given in the RGM formulation of the SUs quark model, in which the full Fermi-Breit interaction with explicit flavor symmetry breaking is incorporated. The medium-range central and long-range tensor components of the hyperon-nucleon interaction are augumented by the effective meson-exchange potentials generated from the scalar-meson nonet and ;r and K mesons of the Nijmegen model-F. With two parameters determined from the deuteron binding energy and NN 'So phase shift, all the low-energy cross sections of the hyperon-nucleon interaction currently available are reasonably reproduced. The analysis of NN and ;I;+p systems is presented.
TL;DR: In this paper, the Liouville equation is derived from the Lindblad's type generator that describes coupling between a quantum particle and a classical, continuous, medium of two-state detectors.
Abstract: The law of track formation in cloud chambers is derived from the Liouville equation with a simple Lindblad's type generator that describes coupling between a quantum particle and a classical, continuous, medium of two--state detectors. Piecewise deterministic random process (PDP) corresponding to the Liouville equation is derived. The process consists of pairs (classical event,quantum jump), interspersed with random periods of continuous (in general, non--linear) Schroedinger's--type evolution. The classical events are flips of the detectors -- they account for tracks. Quantum jumps are shown, in the simplest, homogeneous case, to be identical to those in the early spontaneous localization model of Ghirardi, Rimini and Weber (GRW). The methods and results of the present paper allow for an elementary derivation and numerical simulation of particle track formation and provide an additional perspective on GRW's proposal
TL;DR: In this paper, the authors consider the case of very massive fermions in (2+1) and (1+1)-dimensions and show that the (2 + 1)-dimensional massive Thirring model is equivalent to the massive free scalar field theory.
Abstract: Starting from a reformulation of the Thirring model as a gauge theory, we consider the bosonization of the $D$-dimensional multiflavor massive Thirring model $(D \ge 2)$ with four-fermion interaction of the current-current type. Our method leads to a novel interpolating Lagrangian written in terms of two gauge fields. Especially we pay attention to the case of very massive fermion $m \gg 1$ in (2+1) and (1+1) dimensions. Up to the next-to-leading order of $1/m$, we show that the (2+1)-dimensional massive Thirring model is mapped to the Maxwell-Chern-Simons theory and that the (1+1)-dimensional massive Thirring model is equivalent to the massive free scalar field theory. In the process of the bosonization of the Thirring model, we point out the importance of the gauge-invariant formulation. Finally we discuss a possibility of extending this method to the non-Abelian case.
TL;DR: In this article, boundary effects caused by boundary interactions in various integrable field theories on a half line are discussed at the classical as well as quantum level, and only so-called "integrable" boundary interactions are discussed.
Abstract: Boundary effects caused by boundary interactions in various integrable field theories on a half line are discussed at the classical as well as quantum level. Only so-called "integrable" boundary interactions are discussed. They are obtained by the requirement that certain combinations of the lower members of the infinite set of conserved quantities should be preserved. Contrary to the naive expectations, some "integrable" boundary interactions can drastically change the character of the theory. In some cases, for example, the sinh-Gordon theory, the theory becomes ill-defined due to the instability introduced by "integrable" boundary interactions for a certain range of a parameter.
TL;DR: In this paper, an effective operator e" is defined so that it operates in a restricted model space and gives the same matrix element as that of the original operator e between the corresponding true eigenstates.
Abstract: An effective operator e." is defined so that it operates in a restricted model space and gives the same matrix element as that of the original operator e between the corresponding true eigenstates. The Be" is determined dependently on the model-space eigenstates, and therefore various types of e." are possible. General solutions for e." are derived in the time-independent and algebraic approach. These eJerr contain the usual non-Hermitian and Hermitian effective operators as special cases. The explicit expansion form for Berr is given by extending the Q-box formalism of Kuo et al. developed in the derivation of the effective interaction to the problem of constructing the effective operator.
TL;DR: In this paper, an effective Lagrangian of the mass of the octet baryons interacting with the nucleon/hyperon masses was used to investigate the meson mass in nuclear matter.
Abstract: $\\phi$-meson mass in nuclear matter ($m_{\\phi}^*$) is investigated using an effective Lagrangian of $\\phi$ interacting with octet baryons. $m_{\\phi}^*$ decreases by a few \\% in nuclear matter due to the current conservation and effective nucleon/hyperon masses. Its implication to the p-A and A-A collisions are briefly discussed.
TL;DR: In this article, a detailed quark model study of the AN-IN(/=1/2) system is given in a coupled-channel formulation of the RGM-F which has been recently introduced to achieve a unified understanding of the NN and hyperon-nucleon interaction.
Abstract: A detailed quark-model study of the AN-IN(/=1/2) system is given in a coupled-channel formulation of the RGM-F which has been recently introduced to achieve a unified understanding of the NN and hyperon-nucleon interaction. It is found that the effect of the AN-IN transition potential is strongly enhanced in the threshold region through important contributions of the non central components. The antisymmetric LSH force, which is characteristically strong in the quark model with the full Fermi-Breit interaction, reproduces the prominent bump structure in the AN total scattering cross sections at energies slightly below the IN threshold.
TL;DR: In this article, the Hamilton-Jacobi equation for Brans-Dicke theory is solved by using a long-wavelength approximation, and the non-linear evolution of the inhomogeneities in the dust fluid case and the cosmological constant case is examined.
Abstract: Hamilton-Jacobi equation for Brans-Dicke theory is solved by using a long-wavelength approximation. We examine the non-linear evolution of the inhomogeneities in the dust fluid case and the cosmological constant case. In the case of dust fluid, it turns out that the inhomogeneities of space-time grow. In the case of cosmological constant, the inhomogeneities decay, which is consistent with the cosmic no hair conjecture. The inhomogeneities of the density perturbation and the gravitational constant behave similarly with that of space-time.
TL;DR: In this paper, the three chiral generations of quarks and leptons may be generated through spontaneous breakdown of the noncompact horizontal gauge symmetry, which governs the standard gauge symmetry in a vector-like manner.
Abstract: The three chiral generations of quarks and leptons may be generated through a spontaneous breakdown of the noncompact horizontal gauge symmetry $G_{H}$ which governs, together with the standard gauge symmetry ${SU(3) \times SU(2) \times U(1)}$, the world in a vectorlike manner. In a framework of supersymmetric theory, the simplest choice ${G_{H}=SU(1,1)}$ works quite well for this scenario in which quarks, leptons and Higgses belong to infinite dimensional unitary representation of $SU(1,1)$. The relevance of the scenario to the hierarchical structure of their Yukawa coupling matrices are discussed.
TL;DR: In this paper, hidden sector models of supersymmetry breaking are considered which do not suffer from a cosmological problem due to the Polonyi field and avoidance of a light gluino leads to the introduction of quasi-symmetry.
Abstract: QCD-like hidden sector models of supersymmetry breaking are considered which do not suffer from a cosmological problem due to the Polonyi field. Avoidance of a light gluino leads to introduction of quasi-symmetry -- symmetry broken explicitly only through gravitational effects.