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Showing papers in "Physical Review D in 1992"


Journal ArticleDOI
TL;DR: The experimental limits placed on the oblique correction parameters S and T are reviewed and the value of S can be estimated for running and walking technicolor theories are discussed.
Abstract: I will first review the experimental limits placed on the oblique correction parameters S and T. Then, I will discuss how the value of S can be estimated for running and walking technicolor theories.

2,020 citations


Journal ArticleDOI
TL;DR: It is shown that anisotropies in transverse-momentum distributions provide an unambiguous signature of transverse collective flow in ultrarelativistic nucleus-nucleus collisions.
Abstract: We show that anisotropies in transverse-momentum distributions provide an unambiguous signature of transverse collective flow in ultrarelativistic nucleus-nucleus collisions. We define a measure of the anisotropy from experimental observables. The anisotropy coming from collective effects is estimated quantitatively using a hydrodynamical model, and compared to the anisotropy originating from finite multiplicity fluctuations. We conclude that collective behavior could be seen in Pb-Pb collisions if a few hundred particle momenta were measured in a central event.

975 citations


Journal ArticleDOI
TL;DR: A renormalizable theory of quantum gravity coupled to a dilaton and conformal matter in two spacetime dimensions is analyzed and suggests that the collapsing matter radiates away all of its energy before an event horizon has a chance to form, and black holes disappear from the quantum-mechanical spectrum.
Abstract: A renormalizable theory of quantum gravity coupled to a dilaton and conformal matter in two spacetime dimensions is analyzed. The theory is shown to be exactly solvable classically. Included among the exact classical solutions are configurations describing the formation of a black hole by collapsing matter. The problem of Hawking radiation and back reaction of the metric is analyzed to leading order in a $\frac{1}{N}$ expansion, where $N$ is the number of matter fields. The results suggest that the collapsing matter radiates away all of its energy before an event horizon has a chance to form, and black holes thereby disappear from the quantum-mechanical spectrum. It is argued that the matter asymptotically approaches a zero-energy "bound state" which can carry global quantum numbers and that a unitary $S$ matrix including such states should exist.

911 citations


Journal ArticleDOI
TL;DR: The influence functional path-integral method is used to derive an exact master equation for the quantum Brownian motion of a particle linearly coupled to a general environment at arbitrary temperature and applies it to study certain aspects of the loss of quantum coherence.
Abstract: We use the influence functional path-integral method to derive an exact master equation for the quantum Brownian motion of a particle linearly coupled to a general environment (ohmic, subohmic, or supraohmic) at arbitrary temperature and apply it to study certain aspects of the loss of quantum coherence.

794 citations


Journal ArticleDOI
TL;DR: In this paper, it has been suggested that an advanced civilization might have the technology to warp spacetime so that closed timelike curves would appear, allowing travel into the past.
Abstract: It has been suggested that an advanced civilization might have the technology to warp spacetime so that closed timelike curves would appear, allowing travel into the past This paper examines this possibility in the case that the causality violations appear in a finite region of spacetime without curvature singularities There will be a Cauchy horizon that is compactly generated and that in general contains one or more closed null geodesics which will be incomplete One can define geometrical quantities that measure the Lorentz boost and area increase on going round these closed null geodesics If the causality violation developed from a noncompact initial surface, the averaged weak energy condition must be violated on the Cauchy horizon This shows that one cannot create closed timelike curves with finite lengths of cosmic string Even if violations of the weak energy condition are allowed by quantum theory, the expectation value of the energy-momentum tensor would get very large if timelike curves become almost closed It seems the back reaction would prevent closed timelike curves from appearing These results strongly support the chronology protection conjecture: The laws of physics do not allow the appearance of closed timelike curves

692 citations


Journal ArticleDOI
TL;DR: It is pointed out that the general results pertain to relativistic nuclear collisions in the so-called stopping or baryon-rich domain where there are three conserved charges (baryon, electric, and strangeness), and impact the expected phase transition from confined hadronic matter to quark matter as regards signals that are supposedly driven by pressure.
Abstract: We consider how first-order phase transitions in systems having more than one conserved charge (multicomponent systems) differ from those in systems having only one. In general, the properties of the transition are quite different in the two cases. Perhaps most importantly the pressure varies continuously with the proportion of phases in equilibrium, and is not a constant in the mixed phase as in the example of the gas-liquid transition in familiar one-component systems. We identify the microphysics responsible for the difference. In the case that one of the conserved charges is the electric charge, a geometrical structure in the mixed phase is expected. As an example, possible consequences are developed for the structure of a neutron star in which the transition to quark matter in the core occurs. It is also pointed out that the general results pertain to relativistic nuclear collisions in the so-called stopping or baryon-rich domain where there are three conserved charges (baryon, electric, and strangeness), and impact the expected phase transition from confined hadronic matter to quark matter as regards signals that are supposedly driven by pressure. The physics discussed here is also relevant to the subunclear gas-liquid transition that is under study in lower-energy nuclear collisions.

603 citations


Journal ArticleDOI
TL;DR: It is demonstrated that the familiar suppression of field configurations with a nontrivial topology occurring for small quark masses is a finite size effect which disappears if the four-dimensional volume [ital V] is large enough.
Abstract: We show that very general considerations based on the properties of the partition function of QCD allow one to extract information about the eigenvalues of the Dirac operator in vacuum gauge fields. In particular, we demonstrate that the familiar suppression of field configurations with a nontrivial topology occurring for small quark masses is a finite size effect which disappears if the four-dimensional volume [ital V] is large enough. The formation of a quark condensate is connected with the occurrence of small eigenvalues of order [lambda][sub [ital n]][proportional to]1/[ital V].

576 citations


Journal ArticleDOI
TL;DR: In this article, the lepton number is violated explicitly by charged scalar and gauge bosons, including a vector field with double electric charge, in a model based on a SU(3)-ensuremath{\bigotimes}U(1) symmetry.
Abstract: We consider a gauge model based on a SU(3)\ensuremath{\bigotimes}U(1) symmetry in which the lepton number is violated explicitly by charged scalar and gauge bosons, including a vector field with double electric charge.

565 citations


Journal ArticleDOI
TL;DR: An effective Lagrangian that describes the low-momentum interactions of mesons containing a heavy quark with the pseudo Goldstone bosons and $\ensuremath{\eta}$ is constructed, invariant under both heavy-quark spin symmetry and chiral symmetry.
Abstract: An effective Lagrangian that describes the low-momentum interactions of mesons containing a heavy quark with the pseudo Goldstone bosons $\ensuremath{\pi}$, $K$, and $\ensuremath{\eta}$ is constructed. It is invariant under both heavy-quark spin symmetry and chiral ${\mathrm{SU}(3)}_{L}\ifmmode\times\else\texttimes\fi{}{\mathrm{SU}(3)}_{R}$ symmetry. Implications for semileptonic $B$ and $D$ decays are discussed.

511 citations


Journal ArticleDOI
TL;DR: It is found that the lepton-number-violating out-of-equilibrium decays of right-handed neutrinos combined with anomalous electroweak processes can generate the baryon number of the Universe, and that the scenario works for a wide range of parameters in the neutrino sector.
Abstract: If right-handed Majorana neutrinos are added to the standard model, then lepton-number-violating out-of-equilibrium decays of right-handed neutrinos combined with anomalous electroweak processes can generate the baryon number of the Universe. We analyze this mechanism in detail, and determine the ranges of parameters for which the correct baryon number is generated. We find that the scenario works for a wide range of parameters in the neutrino sector, including right-handed neutrino masses ranging from \ensuremath{\sim}1 TeV to \ensuremath{\sim}${10}^{19}$ GeV, depending on the assumptions made about the structure of the neutrino mass matrices.

503 citations


Journal ArticleDOI
TL;DR: This work implies that the vacuum-bubble collisions associated with strongly first-order phase transition are a very potent cosmological source of gravitational radiation.
Abstract: In the linearized-gravity approximation we numerically compute the amount of gravitational radiation produced by the collision of two true-vacuum bubbles in Minkowski space. The bubbles are separated by distance d and we calculate the amount of gravitational radiation that is produced in a time \ensuremath{\tau}\ensuremath{\sim}d (in a cosmological phase transition \ensuremath{\tau} corresponds to the duration of the transition, which is expected to be of the order of the mean bubble separation d). Our approximations are generally valid for \ensuremath{\tau}\ensuremath{\lesssim}${\mathit{H}}^{\mathrm{\ensuremath{-}}1}$. We find that the amount of gravitational radiation produced depends only upon the grossest features of the collision: the time \ensuremath{\tau} and the energy density associated with the false-vacuum state, ${\mathrm{\ensuremath{\rho}}}_{\mathrm{vac}}$. In particular, the spectrum ${\mathit{dE}}_{\mathrm{GW}}$/d\ensuremath{\omega}\ensuremath{\propto}${\mathrm{\ensuremath{\rho}}}_{\mathrm{vac}}^{2}$${\mathrm{\ensuremath{\tau}}}^{6}$ and peaks at a characteristic frequency ${\mathrm{\ensuremath{\omega}}}_{\mathrm{max}}$\ensuremath{\simeq}3.8/\ensuremath{\tau}, and the fraction of the vacuum energy released into gravitational waves is about 1.3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$(\ensuremath{\tau}/${\mathit{H}}^{\mathrm{\ensuremath{-}}1}$${)}^{2}$, where ${\mathit{H}}^{2}$=8\ensuremath{\pi}G${\mathrm{\ensuremath{\rho}}}_{\mathrm{vac}}$/3 (\ensuremath{\tau}/${\mathit{H}}^{\mathrm{\ensuremath{-}}1}$ is expected to be of the order of a few percent). We address in some detail the important symmetry issues in the problem, and how the familiar ``quadrupole approximation'' breaks down in a most unusual way: it overestimates the amount of gravitational radiation produced in this highly relativistic situation by more than a factor of 50. Most of our results are for collisions of bubbles of equal size, though we briefly consider the collision of vacuum bubbles of unequal size. Our work implies that the vacuum-bubble collisions associated with strongly first-order phase transition are a very potent cosmological source of gravitational radiation.

Journal ArticleDOI
TL;DR: How to determine the sensitivity of these instruments to sources of gravitational radiation by considering the process by which data are analyzed in a noisy detector is examined.
Abstract: The optimum design, construction, and use of the Laser Interferometer Gravitational Wave Observatory (LIGO), the French-Italian Gravitational Wave Observatory (VIRGO), or the Laser Gravitational Wave Observatory (LAGOS) gravitational radiation detectors depends upon accurate calculations of their sensitivity to different sources of radiation. Here I examine how to determine the sensitivity of these instruments to sources of gravitational radiation by considering the process by which data are analyzed in a noisy detector. The problem of detection (is a signal present in the output of the detector?) is separated from that of measurement (what are the parameters that characterize the signal in the detector output?). By constructing the probability that the detector output is consistent with the presence of a signal, I show how to quantify the uncertainty that the output contains a signal and is not simply noise. Proceeding further, I construct the probability distribution that the parametrization $\ensuremath{\mu}$ that characterizes the signal has a certain value. From the distribution and its mode I determine volumes $V(P)$ in parameter space such that $\ensuremath{\mu}\ensuremath{\in}V(P)$ with probability $P$ [owing to the random nature of the detector noise, the volumes $V(P)$ are always different, even for identical signals in the detector output], thus quantifying the uncertainty in the estimation of the signal parametrization. These techniques are suitable for analyzing the output of a noisy detector. If we are designing a detector, or determining the suitability of an existing detector for observing a new source, then we do not have detector output to analyze but are interested in the "most likely" response of the detector to a signal. I exploit the techniques just described to determine the "most likely" volumes $V(P)$ for detector output that would result in a parameter probability distribution with given mode. Finally, as an example, I apply these techniques to determine the anticipated sensitivity of the LIGO and LAGOS detectors to the gravitational radiation from a perturbed Kerr black hole.

Journal ArticleDOI
TL;DR: The flavor and spin symmetry of the heavy quarks and the spontaneously broken approximate SU(3){sub {ital L}}{times} SU( 3){ sub {ital R}} chiral symmetry ofThe light quarks are exploited to formulate a theory describing the low-energy interactions of theheavy mesons and heavy baryons with the Goldstone bosons.
Abstract: The flavor and spin symmetry of the heavy quarks and the spontaneously broken approximate ${\mathrm{SU}(3)}_{L}\ifmmode\times\else\texttimes\fi{}{\mathrm{SU}(3)}_{R}$ chiral symmetry of the light quarks are exploited to formulate a theory describing the low-energy interactions of the heavy mesons ($Q\overline{q}$ bound states) and heavy baryons (${\mathrm{Qq}}_{1}{q}_{2}$ bound states) with the Goldstone bosons $\ensuremath{\pi}$, $K$, and $\ensuremath{\eta}$. The theory contains only three parameters independent of the number of heavy-quark species involved. They can be determined by the decays ${D}^{*}\ensuremath{\rightarrow}D+\ensuremath{\pi}$, ${\ensuremath{\Sigma}}_{c}\ensuremath{\rightarrow}{\ensuremath{\Lambda}}_{c}+\ensuremath{\pi}$, and ${\ensuremath{\Sigma}}_{c}^{*}\ensuremath{\rightarrow}{\ensuremath{\Sigma}}_{c}+\ensuremath{\pi}$. Theoretically, these coupling constants are related, through partial conservation of axial-vector current, to the axial charges of the heavy mesons and the heavy baryons. They are all calculable in the nonrelativistic quark model by using the spin wave functions of these particles alone. The theory is applied to strong decays and semileptonic weak decays of the heavy mesons and baryons. The implications are also discussed.

Journal ArticleDOI
TL;DR: A framework for background-independent open-string field theory is proposed, built into the formalism that classical solutions of the string field theory are Becchi-Rouet-Stora-Tyutin- (BRST-) invariant open- String field theories and that, when expanding around a classical solution, the infinitesimal gauge transformations are generated by the world-sheet BRST operator.
Abstract: A framework for background-independent open-string field theory is proposed. The approach involves using the Batalin-Vilkovisky formalism, in a way suggested by recent developments in closed-string field theory, to implicitly define a gauge-invariant Lagrangian in a hypothetical space of all open-string world-sheet theories.'' It is built into the formalism that classical solutions of the string field theory are Becchi-Rouet-Stora-Tyutin- (BRST-) invariant open-string world-sheet theories and that, when expanding around a classical solution, the infinitesimal gauge transformations are generated by the world-sheet BRST operator.

Journal ArticleDOI
TL;DR: The Parametrized post-Keplerian (PPK) formalism as mentioned in this paper is a general phenomenological framework designed to extract the maximum possible information from pulsar timing and pulse-structure data.
Abstract: Observations of pulsars in gravitationally bound binary systems provide a unique opportunity for testing the strong-field regime of relativistic gravity. We present a detailed account of the "parametrized post-Keplerian" (PPK) formalism, a general phenomenological framework designed to extract the maximum possible information from pulsar timing and pulse-structure data. The PPK approach allows dynamical information to be obtained from the data in a theory-independent way, and encoded in a certain number of fitted post-Keplerian parameters. We show that as many as 19 such parameters can be measured, under favorable conditions, giving access to 15 possible tests of relativistic gravity. We isolate and quantify the theoretical content of these tests by deriving, within the framework of generic boost-invariant theories, expressions linking the phenomenological parameters to the inertial masses of the pulsar and its companion, and to the polar angles of the spin axis of the pulsar. The prospects for extracting some of these tests from observations of known or yet-to-be-discovered binary pulsars is quantitatively assessed through numerical simulations. We show that the recently discovered binary pulsar PSR 1534+12 should, with presently available data, give access to two new strong-field tests of relativistic gravity, if the data are analyzed in the phenomenological way emphasized in this paper. Moreover, in the long run, the first-discovered binary pulsar, PSR 1913+16, could give access to three strong-field tests, beyond the presently obtained $\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{\ensuremath{\omega}}\ensuremath{-}\ensuremath{\gamma}\ensuremath{-}{\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{P}}_{b}$ test. Finally, we show how, by combining the PPK approach with the predictions of a rather generic class of tensor-biscalar theories, one can bring together tests based on observations of several different pulsars. We illustrate how such a combination of independent tests can lead to very tight quantitative constraints on possible strong-field deviations from the correct theory of gravity.

Journal ArticleDOI
TL;DR: This paper includes terms that are cubic in the Higgs condensate in the one-loop effective potential and shows that the standard model has a first-order phase transition.
Abstract: There has been much recent interest in the nature of the electroweak phase transition. This information is of importance in the context of the sphaleron models that have recently been proposed to explain the observed net baryon number in the Universe. The presence of a term that is cubic in the Higgs condensate in the one-loop effective potential appears to indicate a first-order phase transition. However, the infrared singularities inherent in massless models produce cubic terms that are of the same order in the coupling. In this paper, we include these terms and show that the standard model has a first-order phase transition.

Journal ArticleDOI
TL;DR: An improved version of nonrelativistic QCD is constructed for use in lattice simulations of heavy-quark physics, and power-counting rules to assess the importance of the various operators in the action and compute all leading-order corrections required by relativity and finite lattice spacing are developed.
Abstract: We construct an improved version of nonrelativistic QCD for use in lattice simulations of heavy-quark physics, with the goal of reducing systematic errors from all sources to below 10%. We develop power-counting rules to assess the importance of the various operators in the action and compute all leading-order corrections required by relativity and finite lattice spacing. We discuss radiative corrections to tree-level coupling constants, presenting a procedure that effectively resums the largest such corrections to all orders in perturbation theory. Finally, we comment on the size of nonperturbative contributions to the coupling constants.

Journal ArticleDOI
TL;DR: In this paper, Chen and Wu proposed a phenomenological approach to investigate the decay of the effective cosmological constant, which can be generalized to include a term proportional to the time dependence of the Lambda parameter, where $H$ is the Hubble parameter.
Abstract: The phenomenological approach to investigate the decay of the effective cosmological constant, as recently proposed by Chen and Wu, is generalized to include a term proportional to ${H}^{2}$ on the time dependence of $\ensuremath{\Lambda}$, where $H$ is the Hubble parameter This new term can modify some features of the standard Friedmann-Robertson-Walker model and its free parameter may be adjusted in accordance with nucleosynthesis constraints The model also allows a deceleration parameter ${q}_{0}$ assuming negative values so that the density parameter ${\ensuremath{\Omega}}_{0}$ is smaller than ⅔ and the age of the Universe is always bigger than ${H}_{0}^{\ensuremath{-}1}$ In these cases, the usual matter creation rate appearing in models with a decaying vacuum energy is smaller than the one present in the steady-state model

Journal ArticleDOI
TL;DR: A general analytic expression for the probability of the bubble formation is obtained, which may be used for study of tunneling in a wide class of theories, and a decrease of the cubic term by the factor ⅔ rules out baryogenesis in the minimal version of the electroweak theory.
Abstract: We investigate various problems related to the theory of the electroweak phase transition. This includes determination of the nature of the phase transition, discussion of the possible role of the higher-order radiative corrections, and the theory of the formation and evolution of bubbles of the new phase. We show, in particular, that no dangerous linear terms in the scalar field $\ensuremath{\varphi}$ appear in the expression for the effective potential. We have found that, for the Higgs-boson mass smaller than the masses of $W$ and $Z$ bosons, the phase transition is of the first order. However, its strength is approximately ⅔ times less than what follows from the one-loop approximation. The phase transition occurs due to production and expansion of critical bubbles. Subcritical bubbles may be important only if the phase transition is very weakly first order. A general analytic expression for the probability of the bubble formation is obtained, which may be used for study of tunneling in a wide class of theories. The bubble-wall velocity depends on many factors, including the ratio of the mean free path of the particles to the thickness of the wall. Thin walls in the electroweak theory have a nonrelativistic velocity, whereas thick walls may be relativistic. A decrease of the cubic term by the factor ⅔ rules out baryogenesis in the minimal version of the electroweak theory. Even though we concentrate in this paper on the phase transition in this theory, most of our results can be applied to more general models as well, where baryogenesis is possible.

Journal ArticleDOI
TL;DR: A general method to calculate next-to-leading order multijet cross sections is presented, with the emphasis on how to isolate the soft and collinear divergences in multiparton matrix elements.
Abstract: A general method to calculate next-to-leading order multijet cross sections is presented. The emphasis is on how to isolate the soft and collinear divergences in multiparton matrix elements. As an example, the method is used to isolate the divergences at leading order in the number of colours in the processes e+e- + qQ + n gluons and e+e- -t qcjqQ + n gluons. The usual algebraic complexity of calculating next-to-leading order corrections in QCD is avoided, especially the d-dimensional squaring of the real matrix elements and the hard phase space integrals. Some remarks about the stucture of the virtual contributions are made. As a first application, and to examine the feasibility of the approach, explicit Monte Carlo programs are constructed which contain the next-to-leading order corrections to e+e- -+ 2 jets and e+e- + 3 jets. It is demonstrated that the method works and can be readily applied to a variety of processes.

Journal ArticleDOI
TL;DR: The quark and gluon distributions of the photon are determined in leading and higher order by imposing a vector-meson dominance (VMD) valencelike structure at a low resolution scale adopted from the pion.
Abstract: The quark and gluon distributions of the photon are determined in leading and higher order by imposing a vector-meson dominance (VMD) valencelike structure at a low resolution scale adopted from the pion. This leaves only one free parameter, not sufficiently constrained by VMD, to be fixed by experiment. Our predictions are in agreement with presently available data for ${F}_{2}^{\ensuremath{\gamma}}(x,{Q}^{2})$. Simple parametrizations of the resulting parton distributions are presented in the range ${10}^{\ensuremath{-}5}\ensuremath{\lesssim}xl1$, $0.3\ensuremath{\lesssim}{Q}^{2}\ensuremath{\lesssim}{10}^{6}$ ${\mathrm{GeV}}^{2}$ as obtained from the leading- and higher-order evolution equations.

Journal ArticleDOI
TL;DR: Baryogenesis at the electroweak phase transition is tenable in minimal extensions of the standard model with one Higgs doublet because the rate of anomalous baryon-number violation is an exponentially sensitive function of 〈\ensuremath{\varphi}${〉}}_{\mathit{T}}$.
Abstract: We give an analytic treatment of the one-Higgs-doublet, electroweak phase transition which demonstrates that the phase transition is first order. The phase transition occurs by the nucleation of thin-walled bubbles and completes as a temperature where the order parameter 〈\ensuremath{\varphi}${\mathrm{〉}}_{\mathit{T}}$ is significantly smaller than it is when the origin becomes absolutely unstable. The rate of anomalous baryon-number violation is an exponentially sensitive function of 〈\ensuremath{\varphi}${\mathrm{〉}}_{\mathit{T}}$. In very minimal extensions of the standard model it is quite easy to increase 〈\ensuremath{\varphi}${\mathrm{〉}}_{\mathit{T}}$ so that anomalous baryon-number violation is suppressed after the completion of the phase transition. Hence, baryogenesis at the electroweak phase transition is tenable in minimal extensions of the standard model with one Higgs doublet.

Journal ArticleDOI
TL;DR: If {ital d}=10, 11, or 12 these operators can solve the axion domain-wall problem, and this work describes a simple class of Kim-Shifman-Vainshtein-Zakharov axion models where this occurs.
Abstract: It has been argued that quantum gravitational effects will violate all nonlocal symmetries. Peccei-Quinn symmetries must therefore be an accidental'' or automatic consequence of local gauge symmetry. Moreover, higher-dimensional operators suppressed by powers of {ital M}{sub Pl} are expected to explicitly violate the Peccei-Quinn symmetry. Unless these operators are of dimension {ital d}{ge}10, axion models do not solve the strong {ital CP} problem in a natural fashion. A small gravitationally induced contribution to the axion mass has little if any effect on the density of relic axions. If {ital d}=10, 11, or 12 these operators can solve the axion domain-wall problem, and we describe a simple class of Kim-Shifman-Vainshtein-Zakharov axion models where this occurs. We also study the astrophysics and cosmology of heavy axions'' in models where 5{le}{ital d}{le}10.

Journal ArticleDOI
TL;DR: A comprehensive analysis of the running of all the couplings of the standard model to two loops to provide a template for the study of its extensions up to the Planck mass, including threshold effects.
Abstract: In this paper we present a comprehensive analysis of the running of all the couplings of the standard model to two loops, including threshold effects. Our purpose is twofold---to determine what the running of these parameters may indicate for the physics of the standard model and to provide a template for the study of its extensions up to the Planck mass.

Journal ArticleDOI
TL;DR: This paper derives the leading nonlinear hereditary effects in the generation of gravitational radiation, i.e., the terms in the wave form which depend in an irreducible manner on the entire past history of the source.
Abstract: This paper derives the leading nonlinear hereditary effects in the generation of gravitational radiation, i.e., the terms in the wave form which depend in an irreducible manner on the entire past history of the source. At the quadratically nonlinear order there are two types of hereditary contributions. The first ones are due to the readiation of gravitational waves by the stress-energy distribution of (linear) gravitational waves, and give rise to a net cumulative change in the wave form of bursts ("memory effect"). The second ones come from the backscattering of (linear) gravitational waves emitted in the past onto the constant curvature associated with the total mass of the source ("gravitational-wave tails"). An extension of a previously proposed multipole-moment wave generation formalism allows us to compute explicitly the wave form, including hereditary contributions, up to terms of fractional order ${(\frac{v}{c})}^{4}$. Our results are derived for slow-moving systems of bodies, independently of the strength of their internal gravity. The tail contribution to the far wave-zone field is found to be fully consistent with a corresponding hereditary contribution to the gravitational radiation damping previously derived from a study of the near-zone field.

Journal ArticleDOI
TL;DR: How to test the standard-model QCD predictions for the transverse polarization of a top quark produced at the Fermilab Tevatron, Superconducting Super Collider, CERN Large Hadron Collider, and the Next Linear Collider is shown.
Abstract: Once top quarks are found, because they are heavy they will allow many new tests of the standard model (SM) and new probes of physics at the 100-GeV scale. In this paper we show how to test the standard-model QCD predictions for the transverse polarization of a top quark produced at the Fermilab Tevatron, Superconducting Super Collider, CERN Large Hadron Collider, and the Next Linear Collider. We also examine the most general form of the {ital W}-{ital t}-{ital b} vertex, and show how to detect effects of non-SM operators. Ways of detecting non-SM {ital CP}-violation effects in either the production or the decay of the top quarks and top antiquarks are examined.

Journal ArticleDOI
TL;DR: It is shown that extreme dilaton black holes, with electric and magnetic charges, admit supercovariantly constant spinors, and it is speculated on the possibility that an extreme black hole may "evaporate" by emitting smaller extreme black holes.
Abstract: Here we investigate (U(1)j charged dilaton black holes in this context. The extreme solutions are shown to saturate the supersymmetry bound of N = 4, d = 4 supergravity, or dimensionally reduced superstring theory. Specifically, we have shown that extreme dilaton black holes, with electric and magnetic charges, admit supercovariantly constant spinors. The supersymmetric positivity bound for dilaton black holes is given by M & ~ (~Q~+ ~P~). This condition for dilaton black holes coincides with the cosmic censorship requirement that the singularities be hidden, as was the case for other asymptotically Bat static black-hole solutions. We conjecture that the bounds from supersymmetry and cosmic censorship will coincide for more general solutions as well. The temperature, entropy, and singularity of the stringy black hole are discussed in connection with the extreme limit and restoration of supersymmetry. The Euclidean action (entropy) of the extreme black hole is given by 2+~PQ~. We argue that this result is not altered by higher-order corrections in the supersymmetric theory. In the Lorentzian signature, quantum corrections to the effective on-shell action in the extreme black-hole background are also absent. When a black hole reaches its extreme limit, the thermal description breaks down. It cannot continue to evaporate by emitting (uncharged) elementary particles, since this would violate the supersymmetric positivity bound. We speculate on the possibility that an extreme black hole may "evaporate" by emitting smaller extreme black holes.

Journal ArticleDOI
TL;DR: A model which attempts to account for the necessary primordial primordial magnetism by invoking a pseudo-Goldstone boson coupled to electro-magnetism is discussed.
Abstract: The existence of large-scale magnetic fields in galaxies is well established, but there is no accepted mechanism for generating a primordial field which could grow into what is observed today. We discuss a model which attempts to account for the necessary primordial field by invoking a pseudo Goldstone boson coupled to electromagnetism. The evolution of this boson during inflation generates a magnetic field; however, it seems difficult on rather general grounds to obtain fields of sufficient strength on astrophysically interesting scales.

Journal ArticleDOI
TL;DR: The parton distributions of the pion are determined from a consistent next-to-leading-order analysis of several high-statistics π ± N experiments including both Drell-Yan and prompt photon production.
Abstract: We determine the parton distributions of the pion from a consistent next-to-leading-order analysis of several high-statistics π ± N experiments including both Drell-Yan and prompt photon production

Journal ArticleDOI
TL;DR: Neutrino interactions from a 7.7 kton yr exposure of the IMB-3 detector are analyzed and a deficit of nonshowering, or excess of showering, events relative to the total is supported by an independent analysis of muon decay signals.
Abstract: Neutrino interactions from a 7.7 kton yr exposure of the IMB-3 detector are analyzed. A total of 935 contained events radiating over {similar to}50 MeV of {hacek C}erenkov-equivalent energy and consistent with atmospheric neutrino interactions are identified. Of these, 610 have a single {hacek C}erenkov ring. Single-ring interactions are efficiently separated into those containing a showering particle (produced mainly by {nu}{sub {ital e}}) and those containing a nonshowering particle (produced mainly by {nu}{sub {mu}}). In the momentum range 100{lt}{ital p}{sub {ital e}}{lt}1500 MeV/{ital c} and 300{lt}{ital p}{sub {mu}}{lt}1500 MeV/{ital c}, the fraction of nonshowering events is 0.36{plus minus}0.02(stat){plus minus}0.02(syst). Based on detailed models of neutrino production and interaction, a fraction of 0.51{plus minus}0.01(stat){plus minus}0.05(syst) is expected. This deficit of nonshowering, or excess of showering, events relative to the total is supported by an independent analysis of muon decay signals. In the same sample 33{plus minus}2(stat)% of events are accompanied by one or more muon decays, while 43{plus minus}1(stat)% are expected. Further studies that could reduce systematic errors and discover the cause of these discrepancies are suggested.