bluuebunny/crossref_metadata_2025 huggingface dataset:
σ-MODELS AND STRING THEORIES
Authors: RANDJBAR-DAEMI S. , SALAM ABDUS , STRATHDEE J. A.
Published: November 2004

The propagation of closed bosonic strings interacting with background gravitational and dilaton fields is reviewed. The string is treated as a quantum field theory on a compact 2-dimensional manifold. The question is posed as to how the conditions for the vanishing trace anomaly and the ensuing background field equations may depend on global features of the manifold. It is shown that to the leading order in σ-model perturbation theory the string loop effects do not modify the gravitational and the dilaton field equations. However for the purely bosonic strings new terms involving the modular parameter of the world sheet are induced by quantum effects which can be absorbed into a re-definition of the background fields. We also discuss some aspects of several regularization schemes such as dimensional, Pauli-Villars and the proper-time cut off in an appendix.
OPERATOR REGULARIZATION AND THE DIVERGENCE OF THE SUPERCURRENT
Authors: McKEON D. G. C. , SHERRY T. N.
Published: November 2004

Operator regularization is introduced as a procedure to compute Green's functions perturbatively. At the one-loop level the effective action is regularized by means of the ζ-function. A perturbative expansion due to Schwinger allows one to compute from the ζ-function one-loop one-particle irreducible Green's functions. By regulating in this way, we do not have to compute Feynman diagrams, we avoid having to introduce a regulating parameter into the initial Lagrangian and we do not encounter any divergent integrals. This procedure is illustrated for N = 1 super Yang-Mills theory in which the one-loop one-particle irreducible Green's function associated with the decay of the supercurrent into a vector and a spinor particle is treated. Gauge invariance is automatically maintained and the usual anomaly in the divergence of the super-current is recovered.
Standard Model Neutral Higgs Subgroup Summary
Authors: Paige Frank E. , Wang Edward M.
Published: November 2004

Various issues pertaining to the search for the high mass Higgs boson (mH~800 GeV) in the purely leptonic decays of Z pairs are studied. In addition, the usability of a high luminosity SSC (L= 1034/(cm2−s)) in this context is assessed.
Is the Heavy Higgs Boson Observable at the SSC?
Authors: Wang Edward M.
Published: November 2004

The observability of the heavy Higgs boson (mH>2mW) through pure leptonic decays of Z pairs from Higgs and continuum processes is studied. A bump hunt in mZZ is possible for mH<600 GeV. For mH > 600 GeV, precise knowledge of the background rate is essential. The following is a progress report of the Heavy Higgs Working Group for the July 1987 Workshop on Experiments, Detectors and Experimental Areas for the Supercollider to be held in Berkeley, CA.
CONTRIBUTION OF TRANSVERSE GAUGE BOSONS TO HIGGS PRODUCTION AND THE EQUIVALENT VECTOR BOSON APPROXIMATION
Authors: GODBOLE R.M. , OLNESS F.
Published: November 2004

It is shown that for intermediate Higgs masses, in the range 0.3– 0.6 TeV, the contribution σ T of the transversely polarized gauge bosons (V) to the process qq→qqVV→qqH , in the leading log (LL) Equivalent Vector Boson Approximation (EVBA) is comparable to the contribution σ L of the longitudinal ones. As a result the LL EVBA for σ=σ L +σ T overestimates the exact total cross-section by ~100–200 % at the q 1 q 2 centre of mass energies of interest for SSC; viz. 5–10 TeV. An improved formulation of the EVBA leads to modified vector boson densities. These densities lead to an EVBA estimate, including the transverse contributions, which agrees with the exact calculation, for m H as low as 0.3 TeV, within 20–30 % upto quark energies ~5–10 TeV .
SEARCH FOR CHARGED HIGGS BOSONS AT SSC
Authors: Bengtsson Hans-Uno , Yamamoto Hiroaki , Komamiya Sachio
Published: November 2004

We examine the possibility of finding charged Higgs bosons (H±) at the SSC. The charged Higgs boson is produced with a top quark via a gluon+bottom quark interaction (g+b→H+t). For the two Higgs doublet models, H± decays predominantly into t+b. Since the background from QCD processes will be very severe for this decay mode, we studied the H±→τ+ν decay mode. Even for this mode, background from the processes pp→W+t+spectators→ℓ+νℓ+t+spectators will be very high. In the two Higgs doublet models, it is very difficult to extract the charged Higgs signal for reasonable values of the ratio of the two vacuum expectation values ( tan β=v1/v2).
COMPOSITE WEAK BOSONS AT SUPERCOLLIDERS
Authors: Suzuki Mahiko
Published: November 2004

Following a brief survey of nongauge interactions of composite W and Z from a theoretical viewpoint, we point out some of conspicuous signatures of compositeness at supercolliders, in particular, W γ and Z γ productions through [Formula: see text] by interactions of dimension six. In these processes, a suppression factor 1/Λ2 due to compositeness scale Λ is largely compensated by longitudinal polarizations of W and Z, allowing us to probe up to high values of Λ.
PARTON DISTRIBUTION FUNCTIONS AND THE QCD-IMPROVED PARTON MODEL — AN OVERVIEW
Authors: Tung Wu-Ki
Published: November 2004

Some non-trivial features of the QCD-improved parton model relevant to applications on heavy particle production and semi-hard (small-x) processes of interest to collider physics are reviewed. The underlying ideas are illustrated by a simple example. Limitations of the naive parton formula as well as first order corrections and subtractions to it are dis-cussed in a quantitative way. The behavior of parton distribution functions at small x and for heavy quarks are discussed. Recent work on possible impact of unconventional small-x behavior of the parton distributions on small-x physics at SSC and Tevatron are summarized. The Drell-Yan process is found to be particularly sensitive to the small x dependence of parton distributions. Measurements of this process at the Tevatron can provide powerful constraints on the expected rates of semi-hard processes at the SSC.
Small x Physics at the SSC and the Tevatron
Authors: OLNESS FREDRICK , TUNG WU-KI
Published: November 2004

We examine the integrated rates and differential cross-sections for b-quark pair production and Drell-Yan processes at the SSC and the Tevatron colliders, and we determine their sensitivity to a range of possible small x behaviors for the parton distribution functions (PDF’s). We find that both the integrated rates and the differential distributions for the Drell-Yan process are very sensitive to the unknown small x behavior of the PDF’s; whereas, only the integrated rates can distinguish various input PDF’s in the b-pair production process. Experiments at the Tevatron can provide very useful information on small x physics if these two processes, especially Drell-Yan, can be measured.
The Angular Ordering in Soft-Gluon Emission
Authors: Tesima Kiusau
Published: November 2004

The way to evaluate multi-parton cross-sections systematically is discussed. In the leading-double-log approximation in QCD, the successive emission of soft gluons is at successively smaller angles. The angular ordering, however, is violated in the next-to-leading order.
QUANTIZATION OF GRAVITATION WITH WEYL FERMIONS
Authors: SCHAPOSNIK F.A. , VUCETICH H.
Published: November 2004

It is shown that quantization of gravitation consistent with the presence of Weyl fermions is possible, in spite of the existence of Lorentz anomalies: the group of local Lorentz transformations is quantized becoming a physical field and the anomaly is absorbed.
ON THE MULTILOOP CONTRIBUTION TO THE STRING THEORY
Authors: BARANOV M.A. , SCHWARZ A.S.
Published: November 2004

The supermoduli space and the measure on this space arising from fermionic string theory are studied. Analytic properties of this measure are analyzed. Our considerations, combined with previous results by Voronov, give an expression of string measure through analytic superfields and their zeros. The behavior of measure in the vicinity of the boundary of moduli space is studied on the base of this expression.
BARYOGENESIS IN THE INFLATIONARY UNIVERSE —THE INSTANTANEOUS REHEATING MODEL—
Authors: YOKOYAMA JUN’ICHI , KODAMA HIDEO , SATO KATSUHIKO , SATO NOBUAKI
Published: November 2004

Baryogenesis in the inflationary universe is investigated, assuming that the universe is reheated instantaneously. Boltzmann equations are numerically integrated to trace time evolution of asymmetries in quarks and leptons in the Friedmann stage after the reheating, starting from the thermal equilibrium state. It is shown that the sign of the final baryon asymmetry may change depending on the reheating temperature as a result of interplay of superheavy gauge and Higgs bosons, and its mechanism is clarified. Furthermore we suggest a mechanism of generating isocurvature fluctuations which could be the origin of the large scale structure of the universe. It is also found in the instantaneous reheating model that the reheating temperature Ti must satisfy Ti>MH/10 (MH: Higgs boson mass) for the observed baryon/entropy ratio to be explained.
NEW N=2 MATTER COUPLINGS IN SUPERSPACE
Authors: KETOV S.V.
Published: November 2004

The generalized N=2 tensor multiplets are defined and the corresponding interacting models are constructed in N=2 superspace in four dimensions. The couplings with the N=2 Yang-Mills fields are given too. The two-dimensional nonlinear N=4 supersymmetric sigma models obtained via dimensional reduction are known to be finite. The construction gives rise to a variety of explicitly constructed quaternionic-Kähler metrics. Some two-dimensional N=4 supersymmetric sigma models with nonvanishing torsion turn out to be equivalent to the ordinary N=4 hyper-Kähler nonlinear sigma models without torsion.
STATUS OF FRAGMENTATION MODELS
Authors: SJÖSTRAND TORBJÖRN
Published: November 2004

Phenomenological models of multiparticle production have become increasingly important for the interpretation of experimental data in high energy physics. The evolution of these models fills a gap left open by the present limited theoretical understanding of the hadronization process, i.e. the transformation of outgoing colored partons into color singlet hadrons. The three main schools of thought, string fragmentation, cluster fragmentation and independent fragmentation, are presented in this paper. Included are discussions on similarities and differences, successes and failures, and recent developments. Perturbative QCD aspects with strong ties to the multiparticle production picture are also covered, in particular parton showers. An account is given of experience gained in the comparison between data and models. Since fragmentation studies are particularly well developed for e+e− annihilation events, this field is described in detail. A few comments are also presented for leptoproduction and hadron collisions.
PRODUCTION AND DECAYS OF EXTRA GAUGE BOSONS IN A LEFT-RIGHT E6 SUPERSTRING MODEL
Authors: BARGER V. , WHISNANT K.
Published: November 2004

We examine the production and decays of extra gauge bosons Z2 and WR in a recently proposed left-right E6 superstring model with alternative assignments of the fermions in the 27 representation of E6. We find that either [Formula: see text] or [Formula: see text] decay modes may have a branching fraction as high as 6% and 13%, respectively. The bosonic decays of the Z2 are similar to those found in the minimal rank 5 E6 superstring model, except for a possible new [Formula: see text] mode. Allowed regions of Z2 mass versus the Z, Z′ mixing are determined from neutral current data.
GENERALIZED ANALYTIC MAPPINGS AND FLAT-SPACE MODELS OF HAWKING RADIATION
Authors: SANCHEZ N.
Published: November 2004

We generalize the approach to Q.F.T. in accelerated frames based on analytic mappings in a way which stresses further the comparison between the flat and curved space-time situations. Combined linear acceleration with uniform and nonuniform translations or rotations, and nonanalytic but asymptotically analytic mappings are included. A density matrix formulation is given for quantum states at global and asymptotic thermal equilibrium, and the role of the PCT symmetry is discussed. Flat space models of rotating and charged black holes are investigated, together with their surface gravity, chemical potentials, Hawking radiation and superradiance properties.
ELASTIC pd SCATTERING AT HIGH ENERGIES
Authors: BRAUN V.M. , DAKHNO L.G. , NIKONOV V.A.
Published: November 2004

High energy differential pd cross section is calculated in the framework of the multiple scattering theory, inelastic correction included. Special attention is paid to the analysis of the calculation uncertainties. The results agree well with the experimental data obtained at ISR energies in the q2 range 0.06–1.05 (GeV/c) 2. The calculation accuracy is proved to be not worse than 10–20% at q2~0.2 (GeV/c) 2 and much better at small q2, namely, ~1% in the optical point. Prediction for the differential cross section at UNK energy E lab =3 TeV is given.
INDICATIONS OF A ΔI=1/2 RULE IN THE STRONG COUPLING REGIME
Authors: ANGUS IAN G.
Published: November 2004

We will attempt to understand the ΔI=1/2 pattern of the nonleptonic weak decays of the kaons. The calculation scheme employed is the Strong Coupling Expansion of lattice QCD. Kogut-Susskind fermions are used in the Hamiltonian formalism. We will describe in detail the methods used to expedite this calculation, all of which was done by computer algebra.

The final result is very encouraging. Even though an exact interpretation is clouded by the presence of irrelevant operators, and questions of lattice artifacts, a signal of the ΔI=1/2 rule appears to be observable. With an appropriate choice of the one free parameter, enhancements greater than those observed experimentally can be obtained.

We also point out a number of surprising results which we turn up in the course of the calculation.
NUCLEI AS TOPOLOGICAL SOLITONS
Authors: NYMAN EBBE M. , RISKA D.O.
Published: November 2004

The application of the Skyrme model to the construction of interaction and current operators for nuclear systems is reviewed. The long-range behaviors of these operators are found to agree with results of phenomenological meson theories based on effective chiral Lagrangians. The Skyrme model thus provides a compact method for obtaining long-range parts of such operators, consistent with the usual soft-pion theorems as well as with the requirement of current conservation. Predictions of the short-range parts of the operators remain uncertain due to difficulties in solving the equations of motion for the two-nucleon problem. The usual factorized ansatz for the soliton field of the two-nucleon system does not give sufficient accuracy at short range. The possibility of an improvement which would allow the construction of spin and isospin operators for the individual nucleons is discussed. Finally, the Skyrme model is discussed in the limit of large baryon number.
CLASSICAL AND QUANTUM GRAVITY EFFECTS FROM PLANCKIAN ENERGY SUPERSTRING COLLISIONS
Authors: AMATI D. , CIAFALONI M. , VENEZIANO G.
Published: November 2004

We argue that superstring collisions at Planckian energies and small deflection angles are calculable through an evaluation and resummation of string loops in flat space-time. This leads to a systematic expansion of the collision in classical general relativity and quantum string effects. Our results explicitly show how unitarity constraints are recovered through loop corrections and how flat metric calculations reveal the generation of nontrivial geometries by energetic particles. Finite-string-size effects can be evaluated in some regimes and are found to modify classical relativity expectations even at impact parameters much larger than the string scale. Conversely, we find that, through the resummation of large genus contributions, intermediate distance physics provides important classical relativity effects even in the hard, fixed angle regime.
MATTER-COUPLED SUPERGRAVITY WITH GAUSS-BONNET INVARIANTS: COMPONENT LAGRANGIAN AND SUPERSYMMETRY BREAKING
Authors: CECOTTI S. , FERRARA S. , GIRARDELLO L. , PASQUINUCCI A. , PORRATI M.
Published: November 2004

We present the component Lagrangian for the general coupling of N=1 matter to a higher curvature four-dimensional supergravity in which the (curvature)2 terms enter the Lagrangian only through the Gauss-Bonnet and Hirzebruch invariants. This is the situation suggested by the low-energy limit of heterotic strings, after compactification to four dimensions. The model obtained from the string by SU(3)-invariant truncation of the toroidal compactification is discussed in detail. We give the closed-form expression for the scalar potential and discuss supersymmetry breaking via gaugino condensation. We show that, in this last case, the cosmological constant Λ remains exactly zero even when the higher curvature corrections are taken into account. We also discuss briefly the problem of auxiliary field propagation and show that the spurious states decouple (i.e. they get an infinite mass) on the physical vacuum with Λ=0, irrespective of whether SUSY is broken or not. Some new, stringy, developments are discussed in the last section.
LOCAL VACUUM EXCITATIONS IN STRONG ELECTROMAGNETIC FIELDS?
Authors: SCHÄFER ANDREAS , MÜLLER BERNDT , GREINER WALTER
Published: November 2004

We discuss the possibility that strong electromagnetic fields might induce local changes in the vacuum state of the standard model and argue that such states could have all the necessary properties to explain the coincident electron-positron lines observed at GSI. Two specific ideas are investigated. The first relies on the assumption that the Higgs-vacuum state is nearly destabilized by radiative corrections, so that the electric fields produced in heavy ion collisions are strong enough to induce a local phase transition. The second one relies on vacuum changes in the QCD sector. We propose a scenario in which the gluon condensate acquires a [Formula: see text] component and argue that this could change the energy scale of QCD, i.e. ΛQCD.
DIAGONALIZATION OF COLOR FACTORS
Authors: ZEPPENFELD D.
Published: November 2004

The calculation of scattering amplitudes for many colored particles in QCD involves complicated color factors. Using the permutation symmetry of the identical particles present in the scattering process, these color factors can be diagonalized.
A VARIATIONAL APPROACH TO THE GROSS-NEVEU MODEL
Authors: MISHRA H. , MISRA S.P. , MISHRA AMRUTA
Published: November 2004

We solve the instability of perturbative vacuum of Gross-Neveu model by a variational method. The analysis is nonperturbative as it uses only equal time commutator/anticommutator algebra.
INVESTIGATION OF A THEORY WITH SOLITON-LIKE CONFIGURATIONS
Authors: WIEDEMANN A. , MÜLLER-KIRSTEN H.J.W. , TCHRAKIAN D.H.
Published: November 2004

Motivated by the study of classical finite-action field configurations of higher order Yang-Mills-Higgs theories, we construct the Lagrangian of a scalar theory in one space and one time dimensions which can serve as a relatively simple model for the investigation of the properties of theories with finite energy or action classical configurations. The condition of stability of the classical configuration, the zero mode and the significance of the latter in connection with constraints which ensure the existence of the Green’s function, are studied in detail. It is then shown how a Schrödinger equation can be established and solved whose eigenfunctionals determine the probability of field fluctuations in the neighborhood of the classical configuration.
PECULIAR SPIN AND STATISTICS IN TWO SPACE DIMENSIONS
Authors: MACKENZIE R. , WILCZEK FRANK
Published: November 2004

This is an elementary, self-contained review of some peculiarities of quantum mechanics for 2+1 dimensional systems that are at least instructive and perhaps important. In particular, we argue that angular momentum need not be quantized and that statistics interpolating between Fermi and Bose statistics can be constructed. There are possible direct applications to collective excitations in solids and to cosmic strings, and an important moral lesson regarding the “wave function of the universe.”
TWO-DIMENSIONAL (HALF-) INTEGER SPIN CONFORMAL THEORIES WITH CENTRAL CHARGE c<1
Authors: PETKOVA V.B.
Published: November 2004

A generalized integral representation involving two types of charges is explored to construct correlation functions on the plane for c=1–6/(m(m+1))<1 discrete unitary Virasoro series. The various local operator product algebras emerging contain integer, or half-integer, spin fields along with scalar fields. The examples also include a generalization for arbitrary m of the ℤ2-statistics of the Ising model order-disorder fields.
CRITICAL RSOS MODELS AND CONFORMAL FIELD THEORY
Authors: BAZHANOV V. V. , YU. RESHETIKHIN N.
Published: November 2004

The eigenvalues of the transfer matrix of the generalized RSOS model are exactly calculated. From the consideration of the thermodynamics of the quantum system on the one-dimensional chain connected with the RSOS model, we calculate the central charges of the effective conformal field theories describing the critical behavior of the model in different regimes.
IMPLICATIONS OF SYMMETRY BREAKING AND PHENOMENOLOGY FOR SUPERSTRING-BASED MODELS WITH GAUGE SYMMETRY SU(3)C × SU(2)L × SU(2) × U(1) × U(1)′
Authors: MCDONALD J.
Published: November 2004

We discuss symmetry breaking and phenomenological aspects of rank 6 effective models in 4 dimensions, suggested by Calabi-Yau compactification of the heterotic E8 × E8 superstring, which have gauge group SU (3)C × SU (2)L × SU (2) × U (1) × U (1)′. The simplest and most natural form of electroweak symmetry breaking for the softly broken effective SUSY theory is considered, and only those additions and alterations to the 273 based superpotential necessary to eliminate phenomenological problems are made. There are two physically distinct additional SU(2) factors, SU (2)N and SU (2)R. The former has all gauge bosons electrically neutral, the latter both charged and neutral. The additional SU(2) symmetry implies that large Dirac neutrino masses must be eliminated by a see-saw mechanism requiring the introduction of an E6 singlet per generation and an intermediate scale of symmetry breaking MI(≥ 1010 GeV ). The intermediate scale symmetry breaking together with the couplings involving E6 singlets needed for the see-saw mechanism unambiguously determines the form of the superpotential describing physics at low scales ≤ 1 TeV . All additional heavy charge [Formula: see text] quarks and additional Higgs doublets have masses ≤ 1 TeV . An additional U (1)E remains unbroken down to the 1 TeV scale. The resulting effective theories have no U (1)E mediated FCNC due to mixing of heavy and light charge [Formula: see text] quarks. Some couplings must be eliminated in order to prevent rapid nucleon decay. For the 3 generation SU (2)N model the value of sin 2 θω is low but compatible with the range permitted for a model with an extra U (1)E. 4 generation SU (2)N and SU (2)R models are generally ruled out by sin 2 θω. For the SU (2)R models there are two cases depending on whether SU (2)R is broken at M1 or remains unbroken down to the 1 TeV scale. The latter case is ruled out by large sin 2 θω. The former case has acceptable sin 2 θω but is ruled out by large [Formula: see text] mass splitting, leaving only SU (2)N models as a possibility. The SU (2)N symmetry implies that the electron gains a mass either from 1-loop corrections involving heavy charge [Formula: see text] quarks or by more than one pair of Higgs doublets gaining an expectation value. The former can readily generate the correct magnitude of electron mass, but requires suppression of couplings of down-type quarks to additional Higgs doublets by a factor ≥ 102 cf. the Yukawa couplings responsible for quark and lepton masses in order to prevent rapid µ → eγ. It is shown that the SU (2)N model has no possibility of explaining baryogenesis by out of equilibrium particle decays. Flat directions necessary for the Affleck-Dine mechanism of baryogenesis exist only if additional conditions are imposed on the superpotential.
HYPERKAHLER METRICS BUILDING IN THE 1 + 3 REPRESENTATION: THE TAUB-NUT CASE
Authors: EL HASSOUNI A. , LHALLABI T. , OUDRHIRI-SAFIANI E. G. , SAIDI E. H.
Published: November 2004

We construct the HST type hyperkahler N = 2 supersymmetric nonlinear σ model. We show that for 4n dimensional hyperkahler manifolds, one needs in general [Formula: see text] scalar functions to specify the metric. The n = 1 and n = 2 are studied in detail. The SU (2) × U (1) Taub-Nut model in the HST hypermultiplet representation is discussed as an illustrating example. The corresponding Taub-Nut metric is worked out explicitly. Some general features of these models are discussed.
EQUAL VELOCITY RULE IN HEAVY HADRON PRODUCTION AT HIGH ENERGY
Authors: KITAZOE T. , INAZAWA H. , MORII T.
Published: November 2004

A production mechanism of heavy particles in e+e− annihilations is studied on a field theoretical basis using the bound state wave functions. The requirement that wave functions of hadrons overlap maximally with each other leads to the conclusion that (1) the model predicts a 2-jet structure in a one-loop diagram and (2) heavy hadrons in a jet have an equal velocity. Heavy particle production cross sections and their characteristic energy distributions are calculated for some typical reactions.
STRING FIELDS AS LIMIT OF FUNCTIONS AND SURFACE TERMS IN STRING FIELD THEORY
Authors: BORDES JOSÈ , LIZZI FEDELE
Published: November 2004

We consider the String Field Theory proposed by Witten in the discretized approach, where the string is considered as the limit N → ∞ of a collection of N points. In this picture the string functional is the limit of a succession of functions of an increasing number of variables; an object with some resemblances to distributions. Attention is drawn to the fact that the convergence is not of the uniform kind, and that therefore exchanges of limits, sums and integral signs can cause problems, and be ill defined. In this context we discuss some surface terms found by Woodard, which arise in integrations by parts, and argue that they depend crucially on the choice of the successions of function used to define the identity and vertices of the theory.
SPIN CORRELATION EFFECTS IN THE HADROPRODUCTION AND DECAY OF VERY HEAVY TOP QUARK PAIRS
Authors: BARGER V. , OHNEMUS J. , PHILLIPS R. J. N.
Published: November 2004

Density matrix techniques in the helicity basis allow us to write down explicitly the squared matrix elements for tree-level hadroproduction and weak decay of very heavy top quark pairs, that decay before hadronization. This treatment includes the full effects of quark spin correlation. We illustrate the effects of spin correlation on physical distributions in [Formula: see text] dilepton events, [Formula: see text], [Formula: see text], [Formula: see text], for the case mt =120 GeV at [Formula: see text], the energy of the Tevatron collider. The effects of spin correlation are quantitatively small compared to calculations that ignore them, giving corrections of order 10% or less in the physical distributions studied.
QCD AND A CALCULATION OF THE ω − ρ MASS SPLITTING
Authors: ROBERTS C. D. , CAHILL R. T. , PRASCHIFKA J.
Published: November 2004

The mass splitting between the I = 0 ω meson and the I = 1 ρ mesons due to the ππ intermediate state self-energy process accessible to the ρ meson is calculated in a QCD based model of the strong interaction. The calculation is completely self-regularizing with every physical meson quantity used calculable and completely determined by the parameters in the microscopic quark action. The ππ loop integral is convergent with no renormalization necessary. Values for the mass splitting are obtained which are comparable with experiment.
ASPECTS OF SUPERSTRING QUANTUM COSMOLOGY
Authors: ENQVIST K. , MOHANTY S. , NANOPOULOS D. V.
Published: November 2004

We consider the quantum cosmology of a D-dimensional Universe using the point-like field theory effective action of closed bosonic strings. We find that in order to apply the Hartle-Hawking boundary condition, the Universe must have a product topology (like R × Sn × Sm). This rules out four-dimensional theories (unless they are supplemented by extra internal degrees of freedom). We also explain how the Universe evolves from the Euclidean regime (where the space and time are on equal footing) to a macroscopic Lorentzian space Mn+1 and a compact space Km. We find that by demanding the compactified space to be Ricci flat and of the order of Planck scale, we are led uniquely to the conditions D = 10, n = 3, m = 6. We also study the behavior of the gauge coupling constant with time and calculate its asymptotic value.
CAN EXTRA DIMENSIONS STOP GRAVITATIONAL COLLAPSE?
Authors: HENRIQUES A. B.
Published: November 2004

We study some physical consequences of the existence of a compact extra dimension whose scale is assumed to vary with the radial coordinate r. We expect that the gravitational collapse of a star of mass m must have a stop at a radius of the order of 2m.
THE CP PROBLEM IN QUANTUM GRAVITY
Authors: ASHTEKAR ABHAY , BALACHANDRAN A.P. , JO S.
Published: November 2004

It has recently been shown that one can reformulate general relativity in such a way that the canonical variables of the theory resemble those of Yang-Mills theory and the freedom in performing internal rotations on tetrads is completely analogous to the freedom in performing local gauge transformations in Yang-Mills theory. This reformulation is used to carry over, in the canonical framework, the analysis of the θ vacua and the associated CP problem from Yang-Mills theory to general relativity. The analysis depends only on certain qualitative features of general relativity—shared by other field theories of gravitation such as supergravity—and is insensitive to the details of the theory as well as of the way in which the canonical quantization program may be eventually completed.
LARGE-BASIS MESON WAVEFUNCTIONS
Authors: HOLLENBERG LLOYD C. L. , McKELLAR BRUCE H. J.
Published: November 2004

Full O(g) meson wavefunctions are constructed in the context of Perturbative Cavity Dynamics. In addition to the valence [Formula: see text] state these wavefunctions contain [Formula: see text] (Bremsstrahlung) and [Formula: see text] (vacuum fluctuation) configurations. The divergent O(g2) self-energy contributions to the ground state energy are regulated by truncating the basis size and demanding that the bound state mass be independent of the cut-off parameter. This regularization procedure results in a nontrivial cut-off dependence of the model parameters. Parameter functions are computed for the light mesons π-ρ, K-K* and ϕ.
CONSISTENCY CONDITION FOR κ-ANOMALIES AND SUPERSPACE CONSTRAINTS IN QUANTUM HETEROTIC SUPERSTRINGS
Authors: TONIN M.
Published: November 2004

In this paper, the quantum heterotic Green and Schwarz superstring in Yang-Mills and curved superspace background is investigated. A consistency condition for the anomalies, allowing to study their general structure, has been obtained. We have found that the anomalies of the κ-symmetry can be absorbed by consistent quantum corrections of torsion and curvatures leading to superspace constraints in agreement with those considered in recent studies on SUGRA-SYM models. Moreover we suggest that the world sheet conformal and Lorentz anomalies vanish if the κ-anomalies are cancelled.
ALL FREE CONFORMAL REPRESENTATIONS IN ALL DIMENSIONS
Authors: SIEGEL W.
Published: November 2004

We find all free, massless, finite-dimensional, irreducible representations of the conformal group SO(D, 2) in all space-time dimensions D. In odd D they are only the scalar and spinor, but in even D they are all those which are (anti-)self-dual (chiral) on all vector indices. These are exactly the ones described by the mechanics of the extended spinning particle.
STOCHASTIC FIELD THEORY AND RENORMALIZATION GROUP APPROACH TO CRITICAL BEHAVIORS IN THERMO FIELD DYNAMICS
Authors: BHATTACHARYA B.
Published: November 2004

We have studied here the critical behaviors in a simple model from the point of view of the renormalization group at finite temperature utilizing the Stochastic field theoretic approach towards a finite temperature field theory. To this end, thermofield dynamics has been formulated in terms of Stochastic fields in the external and internal space and the thermal average of the two-point correlation function of the internal field functions is related with the order parameter. The thermodynamical functions and the critical phenomena are then studied constructing the generating functionals involving Stochastic fields.
SIX-QUARK CLUSTERS IN NUCLEAR MATTER AT LOW TEMPERATURES
Authors: SHANENKO A.A. , SHUMOVSKY A.S. , YUKALOV V.I.
Published: November 2004

The two-phase system consisting of nucleons and six-quark clusters is investigated. The interaction between nucleons and six-quarks is represented by a sum of the Fermi and Yukawa potentials. The temperature behavior of nucleon and six-quark concentrations versus density is found. It is shown that with a normal nuclear density, six-quark clusters may amount to about 10%, which is in agreement with experiment.
C=I MODELS IN THE THIRRING STRING FORMULATION
Authors: THOMAS STEVEN
Published: November 2004

By introducing the spin field into the Thirring string formulation we complete its conformal algebra and hence construct the generators of the Affine algebra SÛ2L×SÛ2R within the formulation. We present two methods of constructing C=1 orbifolds. In the first, Thirring strings are defined on the double cover of the punctured complex plane; in the second we introduce an analogue of the orbifold space group and use it, along with the known factorization properties of the four-twist correlation function, to deduce the operator product algebra of twist fields. Finally as an application of the formulation we demonstrate the well-known equivalence of free strings compactified on the circle and orbifold at the multicritical point.
SYSTEMATIC STUDIES OF THE EVEN GD AND DY ISOTOPES WITHIN THE INTERACTING BOSON APPROXIMATION
Authors: YEN M.M. KING , HSIEH S.T.
Published: November 2004

The low-lying collective states of five Gd isotopes and six Dy isotopes are interpreted fairly simply by a four term Hamiltonian in IBA-1. The variation in the interaction parameter is kept to a minimum and can be correlated to the limiting symmetries. The electric quadrupole reduced transition probabilities are also calculated.
NEW FINDINGS IN QUANTUM MECHANICS (PARTIAL ALGEBRAIZATION OF THE SPECTRAL PROBLEM)
Authors: SHIFMAN M.A.
Published: November 2004

We discuss a new class of spectral problems discovered recently which occupies an intermediate position between the exactly-solvable problems (like the famous harmonic oscillator) and all others. The problems belonging to this class are distinguished by the fact that an (arbitrary) part of the eigenvalues and eigenfunctions can be found algebraically, but not the whole spectrum. The reason explaining the existence of the quasi-exactly-solvable problems is a hidden dynamical symmetry present in the Hamiltonian. For one-dimensional motion, this hidden symmetry is SU(2). The simplest one-dimensional system admitting algebraization for a part of the spectrum is the anharmonic oscillator with the x6 anharmonicity and a relation between the coefficients in front of x2 and x6. We review also more complicated cases with the emphasis on pedagogical aspects. The groups SU (2)× SU (2), SO(3) and SU(3) generate two-dimensional problems with the partial algebraization of the spectrum. Typically we get Schrödinger-type equations in curved space. An intriguing relation between the algebraic structure of the Hamiltonian and the geometry of the space emerges. Another interesting development is the use of the graded algebras which allow one to construct multi-component quasi-exactly-solvable Hamiltonians.
SEPARATING STATIONARY AXIALLY-SYMMETRIC ASYMPTOTICALLY FLAT METRICS
Authors: TURAKULOV Z. YA.
Published: November 2004

Stationary axially-symmetric asymptotically flat metrics allowing the complete separation of variables in the Klein-Gordon equation are considered. It is shown that if such metrics coincide at infinity with the metric of spherical system of coordinates, the variables for them in the Einstein equation are completely separable and the only vacuum solution is the Kerr metric.
VERTEX OPERATOR CONSTRUCTION OF UNITARY CONFORMAL THEORIES
Authors: NEVEU A. , WEST P.
Published: November 2004

We give a manifestly unitary construction of large classes of two-dimensional conformal theories, including the minimal series. This construction is based on the inclusion of vertex operators of naive dimension two in the conformal generators. Closure of the conformal algebra imposes restrictions on the corresponding momenta of the vertex operators which in particular are satisfied by the scaled root diagram of simply-laced groups. This provides a new connection between Lie groups and certain conformal theories, in particular the minimal ones.
QUASAR CLUSTERING AND ITS COSMOLOGICAL IMPLICATION
Authors: FANG LI ZHI
Published: November 2004

The clusterings of quasars and absorption line clouds have been analyzed from the viewpoint of the structure formation of the universe. It was found that the features of quasar clustering are quite different from those of galaxies. These results have already given several meaningful constraints on the structure formation, as follows: (a) quasar clustering is much weaker than in galaxies; (b) large scale structures, such as superclusters, should probably be formed after the epoch z~2; (c) the amplitude of the total density inhomogeneity seems to be less than that of galaxy distribution by at least a factor of 3–5 (in a Ω=1 universe); (d) Ly-α absorption clouds may be formed by different processes of clustering from that of glaxies.
SPACE-TIME PROPAGATION OF CONFINED GLUONS
Authors: CELENZA L. S. , SHAKIN C. M. , WANG HUI-WEN , YANG XIN-HUA
Published: November 2004

We assume that there is gluon condensate in the zero-momentum mode in the QCD ground state. A lowest-order calculation in terms of a condensate order parameter leads to a dynamical mass for gluons via the Schwinger mechanism and a gluon propagator with no on-mass-shell singularities — that is, the gluon is a "nonpropagating mode" in the gluon condensate. We transform our momentum-space propagator into coordinate space and find that the propagator has essentially the same delta-function light-cone singularities as the free propagator. However, in contrast to a theory without confinement, we show that the propagator exhibits exponential decay, both for time-like and space-like propagation. In this manner, we obtain a space-time characterization of the confinement phenomenon in terms of an order parameter of the condensate.
F-SPIN SYMMETRY BREAKING: APPLICATION TO THE U(5) AND SU(3) LIMIT
Authors: DE COSTER C. , HEYDE K.
Published: November 2004

Starting from the U(5) and SU(3) dynamic symmetries, perturbations on an F-spin scalar IBM-2 Hamiltonian are studied. The parameters describing the perturbations are chosen such as to introduce only the F-spin vector and the F-spin tensor terms of rank two. Effects on the F-spin structure of the wave functions, excitation energies and electromagnetic transition probabilities are studied for the lowest symmetric and mixed-symmetry states. If possible, numerical results are compared to analytic expressions derived via the first-order perturbation calculations.
ON SUPERSYMMETRIC EXTENDED CONFORMAL ALGEBRAS AND SUPER KP HIERARCHY
Authors: NAM SOONKEON
Published: November 2004

We consider a possible supersymmetric generalization of the extended conformal algebra with a Z3 symmetry. By drawing analogy from the connection of the KdV hierachy and the conformal algebra, which is a particular case of KP hierachy, we approach the problem in a superspace formalism of the super KP hierachy. A generalization of the Miura transformation and accompanying factorization of the Lax operator is examined. We conclude that the nontrivial factorization of the Lax operator is impossible and thus a nontrivial supersymmetric version of the extended conformal algebra cannot be constructed. We argue that the impossibility is due to the incompatibility of the Z2 grading and Z3 symmetry of the system.
PHASE SPACE IN SINGULAR THEORIES
Authors: GOGILIDZE S. A. , SANADZE V. V. , TKEBUCHAVA F. G. , SUROVTSEV YU. S.
Published: November 2004

The method is formulated for constructing the generators of gauge transformations in the phase space for a given singular Lagrangian. These generators are used to impose the necessary and sufficient conditions on gauge functions. The results are analyzed for particular examples.
C. Y. CHAO, PAIR CREATION AND PAIR ANNIHILATION
Authors: LI BING AN , YANG C. N.
Published: November 2004

C. Y. Chao's contribution to physicists' acceptance of QED in 1933–1934 through his experiments of 1930 is analyzed. It is pointed out that Blackett and Occhialini's key suggestion of 1933 about hole theory was based on identifying Chao's "additional scattered rays" (1930) as due to pair annihilation.
AN EXPLICIT COMPUTATION FOR THE BOSE-FERMI EQUIVALENCE ON RIEMANN SURFACES OF GENUS g
Authors: CHAIR NOUREDDINE
Published: November 2004

The instanton sum in the partition function for D bosons on a Riemann surface of genus g, with values in a general D-dimensional torus, TD = RD/ΛD is given explicitly. When the rational metric Q of the lattice, ΛD, is the identity we get the bosonization formula of Alvarez-Gaumé et al. for SO( 2D ). If Q is orthogonal, in the bosonization formula, we get the theta function associated with the quadratic form Q, if Q is generic we get rational Conformal Field Theory. Also we look for conditions on a twisted spin bundle LE, which may ensure that our partition functions arise from some generalized bosonization formulas.
A NOTE ON THE FRADKIN-VILKOVISKY THEOREM
Authors: GOVAERTS JAN
Published: November 2004

It is argued that the usual statement of the Fradkin-Vilkovisky theorem, which determines the dependence of the path-integral for gauge-invariant systems on their gauge-fixing, cannot be correct. A more precise statement is given, by considering the structure of the modular space of gauge orbits. The discussion is illustrated in the case of the scalar particle with specific examples.
MINIMAL QUANTIZATION OF ANOMALOUS TWO-DIMENSIONAL GAUGE MODELS
Authors: ILIEVA N. P.
Published: November 2004

Two-dimensional gauge models with chiral anomalies — "left-handed" QED and the chiral Schwinger model are consistently quantized in the frames of the minimal quantization method. The choice of the cone time as a physical time for the system of quantization is motivated. The well-known mass spectrum is found but with a fixed value of the regularization parameter a = 2. Such a unique solution is obtained due to the strong requirement of self-consistency of the minimal quantization method that is reflected in the physically motivated choice of the time axis.
PHYSICS: ITS DEVELOPMENT AND PHILOSOPHY
Authors: WU TA-YOU
Published: November 2004

We attempt to review the development of physics in its historical order: classical dynamics; optics and electromagnetic theory followed naturally by the special theory of relativity; the general theory of relativity; from another direction, the kinetic theory of gases, thermodynamics and statistical mechanics which led to the discovery of the quantum theory; atomic physics that led to quantum mechanics; the theoretical and experimental studies of elementary particle physics. Some efforts were made to bring out the basic concepts in these theories and their changes, namely, the abandoning of the absolute time and simultaneity, simultaneous exact knowledge of position and momentum of a particle and determinism of Newtonian physics in the relativity theory and quantum mechanics; the concept of quantized field and unified fields. The interplay between experiments and theories in the development of physics was summarized by a table at the end of the article.
BRST QUANTIZATION OF THE TYPE II GREEN-SCHWARZ STRING
Authors: XU RUI-MING
Published: November 2004

By performing the BRST quantization for the Type II Green-Schwarz string with the truncated κ-symmetry recently proposed by Kallosh and Rahmanov, we confirm that the quadratic ghost interaction is indeed sufficient for the unitarity of the theory. The analysis of the cancellation of the conformal anomaly gives the correct critical dimension.
THE GAUGE DEPENDENCE OF THE EFFECTIVE ACTION OF COMPOSITE FIELDS IN GENERAL GAUGE THEORIES
Authors: LAVROV P. M. , ODINTSOV S. D.
Published: November 2004

The gauge dependence of the effective action of composite fields is investigated. The Ward identities for general gauge theories with arbitrary composite fields are found. It is proved that the extremum of the action of composite fields does not depend on the gauge condition. An example of the calculation of the effective action of composite fields in Yang-Mills theory is discussed.
TWO-PHOTON ANNIHILATION INTO PROTON-ANTIPROTON IN A QUARK-DIQUARK SCHEME
Authors: ANSELMINO M. , CARUSO F. , KROLL P. , SCHWEIGER W.
Published: November 2004

We consider [Formula: see text] in the framework of the Brodsky-Farrar-Lepage scheme allowing for (scalar) diquarks as quasi-elementary constituents. We compute the unpolarized cross section using different proton wave functions. Their normalization is fixed by computing the electromagnetic form factor of the proton in the same framework. Good agreement with the experimental data can be obtained. Two-photon annihilation into other baryons is also discussed.
AN INTEGRABLE XY-MODEL REVISITED
Authors: KLINKHAMER F. R.
Published: November 2004

An exactly solvable two-dimensional model of Fateev and Zamolodchikov is shown to approach, in a certain limit, the standard XY-model at zero temperature. This model may be of some relevance to strings (and to knot theory perhaps).
CHARMONIUM AND BOTTOMIUM SPECTRA IN THE STATISTICAL MODEL
Authors: BANERJEE S. N. , CHAKRABARTI BALLARI , SARKER A. K.
Published: November 2004

The spectroscopic properties of the charmonium (Ψ) and bottomium (ϒ) families have been studied in the framework of the statistical model. The energy splittings of the S, P, D levels of Ψ and ϒ-families have been investigated using one-gluon exchange potential containing the running coupling constant, as a perturbation over the already existing confinement type of potentials. Our computed results are found to be in reasonably good agreement with the corresponding experimental findings and/or other theoretical estimates.
LASER SPECTROSCOPY, PAST, PRESENT, AND PERHAPS FUTURE
Authors: SCHAWLOW ARTHUR L.
Published: November 2004

Historically, observations of the spectra of simple atoms have led to much of our understanding of the laws of physics. Recently, with tunable lasers, we are able to extend these observations with enormously increased resolution, sensitivity, and precision. There are a number of methods for overcoming the Doppler broadening of spectral lines. As little as a single atom can be observed and studied, by resonance fluorescence or photoionization. Complex spectra can be simplified in systematic ways by laser labeling of chosen levels. These and other advances in techniques are being applied to improve the measurement of fundamental constants, and to test the basic laws of physics.