bluuebunny/crossref_metadata_2025 huggingface dataset:
Recruitment of Picea mariana, Pinus banksiana, and Populus tremuloides across a burn severity gradient following wildfire in the southern boreal forest of Quebec
Authors: Greene D F , Noël J , Bergeron Y , Rousseau M , Gauthier S
Published: October 2004

Most studies of postfire tree recruitment have occurred in severely burned portions, despite the fact that partial burning is common. In this study we examined regeneration following a 1997 fire in the boreal forest of Quebec. A model of postfire recruitment was elaborated using parameters such as the proportion of trees killed (severity), the proportions of postfire seedbed types and their associated juvenile survivorship, the available seed supply, the available bud supply (for Populus tremuloides Michx.), and the granivory rate. All three species had peak recruitment in the first or second summer, and the recruitment episode was essentially finished after the third year. Mineral soil and surviving Sphagnum were the best seedbeds for both conifer species. Seedbed frequency was essentially independent of crown fire severity except for surviving Sphagnum, which was concentrated primarily where severity was light. Conifer fecundity was much lower in the lightly burned stands, a result we attribute to a higher granivory rate. The fecundity (seedlings/basal area for the conifers or suckers/basal area for Populus) in the severe sites was typical of the few other North American studies of postfire recruitment, where the published data permit us to make the comparison.
Loss and recovery of ecosystem carbon pools following stand-replacing wildfire in Michigan jack pine forests
Authors: Rothstein David E , Yermakov Zhanna , Buell Allison L
Published: October 2004

We used a 72-year chronosequence to study the loss and recovery of ecosystem C pools following stand-replacing wildfire in Michigan, USA, jack pine (Pinus banksiana Lamb.) forests. We quantified the amount of C stored in aboveground plant biomass, standing dead timber, downed dead wood, surface organic soil, and mineral soil in 11 jack pine stands that had burned between 1 and 72 years previously. Total ecosystem C ranged from a low of 59 Mg C·ha1 in the 4-year-old stand to 110 Mg C·ha1 in the 72-year-old stand. Changes in total ecosystem C across the chronosequence conformed to theoretical predictions, in which C stocks declined initially as decomposition of dead wood and forest-floor C exceeded production by regenerating vegetation, and then increased asymptotically with the development of a new stand of jack pine. This pattern was well described by the following "gamma" function: total ecosystem C (Mg·ha1) = 112.2  39.6 × age0.351 × exp(0.053 × age01.039); mean-corrected R2 = 0.976. Using the first derivative of this parameterized gamma function, we estimated that jack pine stands function as a weak source of C to the atmosphere for only ca. 6 years following wildfire, and reach a maximum net ecosystem productivity of 1.6 Mg C·ha1·year1 by year 16. We attribute the rapid transition from carbon source to carbon sink in these ecosystems to two factors: (i) stand-replacing wildfires in these xeric forests leave behind little respirable substrate in surface organic horizons, and (ii) jack pine is able to rapidly reestablish following wildfires via serotinous cones. Jack pine stands remained net sinks for C across the chronosequence; however, net ecosystem productivity had declined to 0.12 C ha1·year1 by year 72. Carbon sequestration by mature jack pine ecosystems was driven primarily by continued growth of overstory jack pine, not by accumulation of detrital C.
Short-term effects of cut-to-length versus full-tree harvesting on conifer regeneration in jack pine, mixedwood, and black spruce forests in Manitoba
Authors: Waters Isobel , Kembel Steven W , Gingras Jean-François , Shay Jennifer M
Published: October 2004

This study compares the effects of full-tree versus cut-to-length forest harvesting methods on tree regeneration in jack pine (Pinus banksiana Lamb.), mixedwood (Picea glauca (Moench) Voss  Populus tremuloides Michx.  Abies balsamea (L.) Mill.), and black spruce (Picea mariana (Mill.) BSP) sites in southeastern Manitoba, Canada. We surveyed tree regeneration densities, disturbance characteristics, and understorey vegetation in replicated control and harvested plots in each site type preharvest (1993) and 1 and 3 years postharvest (1994, 1996). In jack pine sites, the full-tree harvest method promoted regeneration of Pinus banksiana through increased disturbance of soil and the moss layer, and decreased slash deposition relative to the cut-to-length method. Conversely, in mixedwood sites the cut-to-length method resulted in less damage to advance regeneration and proved better at promoting postharvest regeneration of Abies balsamea and Picea glauca relative to the full-tree method. In black spruce sites, there were few differences in the impact of the two harvesting methods on regeneration of Picea mariana, which increased in frequency and density after both types of harvesting.
Importance of large woody debris for juvenile chinook salmon habitat in small boreal forest streams in the upper Yukon River basin, Canada
Authors: Mossop Brent , Bradford Michael J
Published: October 2004

The importance of large woody debris (LWD) in forested stream ecosystems is well documented. However, little is known about LWD in northern boreal forest streams. We investigated the abundance, characteristics, and function of LWD in 13 small tributary streams of the upper Yukon River basin, Yukon Territory, Canada. LWD abundance was similar to values reported from temperate regions, whereas LWD size and total volume were well below values for the Pacific Northwest. LWD formed 28% of the pools, which provide important habitat for juvenile chinook salmon (Oncorhynchus tshawytscha Walbaum). The median diameter of pool-forming pieces was 17 cm, and ring counts on fallen riparian trees indicated that pool-forming pieces were likely 70200 years old when downed. Juvenile chinook salmon density was correlated with LWD abundance in our study reaches. We conclude that despite differences in climate and forest type, LWD in Yukon streams and LWD in temperate regions appear to perform a similar function in creating fish habitat. Resource managers should consider the relatively slow tree growth and thus potentially long recovery times following human disturbances in these watersheds.
Conifer response to three silvicultural treatments in the Oregon Coast Range foothills
Authors: Walter Scott T , Maguire Chris C
Published: October 2004

This study assessed growth, condition, and mortality of residual trees one decade after harvest across three silvicultural treatments in thirty 85- to 125-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in the Oregon Coast Range foothills. Group-selection cuts had 33% of the entire stand volume extracted as patches approximately 0.20.8 ha in size; two-story regeneration harvests had 75% of the volume extracted, and 2030 residual trees/ha were left; clearcuts had all trees removed, except for 1.2 trees/ha. One decade after harvest, tree basal area, diameter, and height growth, and crown width and fullness did not differ between silvicultural treatments. In contrast, live crown ratio was largest in clearcuts (0.74), and the proportion of trees with epicormic branching was highest in two-story stands (35%). Overall, 45% of trees had more basal area growth in the decade after harvest than in the previous decade. Residual green trees in clearcuts and group-selection stands experienced the highest and lowest percentage mortality, respectively (30.6% vs. 0.2%). Our results reflect little differentiation in the characteristics of trees growing under three silvicultural conditions one decade after harvest. However, percent residual green tree mortality increased with increasing harvest intensity.
Belowground to aboveground biomass ratio and vertical root distribution responses of maturePinus radiatastands to phosphorus fertilization at planting
Authors: Zerihun Ayalsew , Montagu Kelvin D
Published: October 2004

We compared the belowground biomass (BGB)/aboveground biomass (AGB) ratio and the vertical root distribution of 40-year-old Pinus radiata D. Don fertilized with 0 or 90 kg P·ha1at planting. Root biomass was determined by a combination of coring (fine roots, ϕ < 2 mm; small roots, 2 ≤ ϕ < 15 mm) and excavation (coarse roots, ϕ ≥ 5 mm). Stand-level AGB and coarse root biomass (CRB) were estimated with the use of allometric relations. After 40 years, AGB and CRB of P-fertilized trees were 4.5 times those of unfertilized trees, indicating that CRB scaled isometrically with AGB independently of P supply. By contrast, P fertilization increased the fine and small root biomass (FSRB) pool by only 50%. As a result, the scaling of FSRB to AGB was dependent on P supply. The differential response of the FSRB to P fertilization caused the overall BGB/AGB ratio to decrease from 0.29 in control plots to 0.20 in P-fertilized plots. Phosphorus fertilization also altered the vertical distribution of fine root biomass (FRB). For example, the proportion of FRB in the top 15 cm increased from 41% to 52% with P fertilization. Collectively, the results showed that P added early in the growth phase had a persistent effect on the BGB/AGB ratio in P. radiata. This was primarily brought about by altered biomass partitioning to the nutrient-acquiring FSRB pool.
Error-in-variable method to estimate parameters for reciprocal base-age invariant site index models
Authors: Wang Yonghe , Huang Shongming , Yang Richard C , Tang Shouzheng
Published: October 2004

Difference equations are widely used in forest productivity studies, especially in the construction of base-age invariant site index curves. A major problem associated with these equations is that several structures derived from original stem analysis data have to be considered for parameter estimation, and the compatibility of the estimated parameters using the ordinary least squares method is not guaranteed. The error-in-variable method is a parameter estimation method that ensures the compatibility of estimated parameters for the reciprocal base-age invariant models. In this study, we employed this method to estimate parameters for the base-age invariant models, based on several data structures consisting of two heights at two separate ages, and this method and the ordinary least squares method were compared. The error-in-variable method rendered the parameters compatibility without the need to specify dependent and independent variables. It also reduced the number of data structures such that the construction of the site index curves could be simplified.
Nonsymbiotic nitrogen fixation in 3-year-old Jeffrey pines and the role of elevated [CO2]
Authors: Verburg P SJ , Cheng W , Johnson D W , Schorran D E
Published: October 2004

Increased belowground labile C inputs under elevated [CO2] could stimulate nonsymbiotic N2 fixation, thereby enhancing growth responses of vegetation to elevated [CO2] on nutrient-poor sites. To test this hypothesis, nonsymbiotic N2 fixation rates in soils planted with 3-year-old Jeffrey pine (Pinus jeffreyi Grev. & Balf.) trees grown under 365 and 700 µL·L1 atmospheric [CO2] were measured by exposing the soil to 15N2-enriched air for 78 d. Nitrogen fixation rates were estimated by measuring 15N content of trees and soil. Compared with the ambient CO2 treatment, the elevated CO2 treatment did not affect biomass, N content, or δ15N of individual plant parts and soils, indicating that elevated [CO2] did not stimulate nonsymbiotic N2 fixation. Because belowground C inputs did not increase under elevated [CO2], the initial hypothesis could not be accepted or rejected. The results from the 15N2 labeling study agree with other studies showing that nonsymbiotic N2 fixation is not likely to provide a large input of N in forest ecosystems. The 15N2 labeling technique was promising for studying N2 fixation in plantsoil systems, but the preliminary nature of this study did not allow for firm conclusions with regard to the effects of elevated [CO2].
Variation in radial growth patterns of Pseudotsuga menziesii on the central coast of British Columbia, Canada
Authors: Zhang Qi-Bin , Hebda Richard J
Published: October 2004

Radial growth of trees in mountainous areas is subject to conditions associated with changes in elevation. We present ring-width chronologies for Douglas-fir trees (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) at nine sites spanning low to high elevations in the Bella Coola area of the central coast of British Columbia, near the northern limits of the species distribution, and investigate the variation in tree-ring growth patterns in relation to different elevations, using principal component (PC) analysis. We find that the first PC, which represents 55.6% of the total variance, reflects a common growth response at sites of different elevation. Response function analysis indicates that growing season precipitation is the major factor in controlling tree-ring growth. This factor explains more of the variance in low-elevation sites than it does in high-elevation ones. Temperature in August of the preceding year shows a negative relationship to ring-width growth. The second PC represents 16.7% of the total variance and reveals a distinct difference in growth response between low- and high-elevation sites. The length and temperature of the growing season seem to play an important role in tree-ring growth at sites of high elevation. Comparison of the Bella Coola records with those from southern Vancouver Island suggests that growing season precipitation influences growth of Douglas-fir on a macroregional scale, but other factors such as temperature modify the growth response at the limits of the distribution of the species.
Are temperate mixedwood forests perceived by birds as a distinct forest type?
Authors: Girard Caroline , Darveau Marcel , Savard Jean-Pierre L , Huot Jean
Published: October 2004

Forestry practices used in mixedwood forests have led to a reduction of the availability of mixedwood stands and to a simplification of the forest mosaic, with unknown consequences on wildlife. We assessed bird occurrences at different spatial scales (50-, 100-, and 1000-m radius) in response to coniferous, deciduous, and mixedwood stands within the Quebec balsam fir  yellow birch domain. Our objective was to evaluate whether birds perceive temperate mixedwood forests as distinct from deciduous and coniferous forests. We quantified bird occurrence at 57 observation points and determined habitat composition from forest maps. At the 50-, 100-, and 1000-m scales, the occurrence of two, four, and four species, respectively, was positively related to mixedwood stands. Among them the Blackburnian Warbler, the Northern Parula, the Black-throated Blue Warbler, and the Ovenbird responded at more than one scale. Some species were also influenced by coniferous and deciduous stands at the three spatial scales. Mixedwood stands were positively associated with the occurrence of many species and moreover were preferred over coniferous or deciduous stands by some species. These results support our hypothesis that mixedwood forests are distinct habitats and provide a new justification for preserving this forest type.
SUPERSYMMETRIC PARTICLE PRODUCTION AT HERA
Authors: KOBAYASHI TETSURO , KITAMURA SHOICHI , KON TADASHI
Published: October 2004

In the framework of the minimal supersymmetric standard model and the R-parity-breaking model, we investigate various production processes of the supersymmetric partner at HERA energies. Emphasis is placed upon the scalar top quark (the partner of the top quark), which is characterized by its having lighter mass than the top quark and other scalar quarks in a model. We propose experimentally feasible approaches to searching for clean signals of the stop from either its production or decay processes.
GEOMETRICAL PROPERTIES OF CONFORMAL FIELD THEORIES COUPLED TO TWO-DIMENSIONAL QUANTUM GRAVITY
Authors: BRAUNE S.
Published: October 2004

In this work we discuss an approach due to F. David to the geometry of world sheets of noncritical strings in quasiclassical approximation. The gravitational dressed conformal dimension is related to the scaling behavior of the two-point function with respect to a distance variable. We show how this approach can reproduce the standard gravitational dressing in the next order of perturbation theory. Furthermore, we try to find this scaling dimension by studying the functional integral. With the same technique we calculate the intrinsic Hausdorff dimension of a world sheet.
NONPERTURBATIVE EFFECTIVE ACTIONS OF (N=2)-SUPERSYMMETRIC GAUGE THEORIES
Authors: KLEMM A. , LERCHE W. , THEISEN S.
Published: October 2004

We elaborate on our previous work on (N=2)-supersymmetric Yang-Mills theory. In particular, we show how to explicitly determine the low energy quantum effective action for G=SU(3) from the underlying hyperelliptic Riemann surface, and calculate the leading instanton corrections. This is done by solving Picard-Fuchs equations and asymptotically evaluating period integrals. We find that the dynamics of the SU(3) theory is governed by an Appell system of type F4, and compute the exact quantum gauge coupling explicitly in terms of Appell functions.
EXCITATION SPECTRA OF SPIN MODELS CONSTRUCTED FROM QUANTIZED AFFINE ALGEBRAS OF TYPES ${\rm B}_n^{\left( 1 \right)}$ and $D_n^{\left( 1 \right)}$
Authors: DAVIES BRIAN , OKADO MASATO
Published: October 2004

The energy and momentum spectra of the spin models constructed from the vector representation of the quantized affine algebras of types [Formula: see text] and [Formula: see text] are computed using the approach of Davies et al.1 The results are for the antiferromagnetic (massive) regime, and they agree with the mass spectrum found from the factorized S matrix theory by Ogievetsky et al.2 The other new result is the explicit realization of the fusion construction for the quantized affine algebras of types [Formula: see text] and [Formula: see text].
HERA+LC-BASED γp COLLIDER: LUMINOSITY AND PHYSICS
Authors: AYDIN Z.Z. , ALAN A.T. , ATAĞ S. , ÇAKIR O. , ÇELIKEL A. , ÇIFTÇI A.K. , KANDEMIR A. , SULTANSOY S. , TÜRKÖZ Ş. , YAVAŞ Ö. , YILMAZ M. , YILMAZER A.U.
Published: October 2004

We discuss the possibility of constructing a linac ring type ep collider and a γp collider based on it at DESY, namely the HERA+LC proposal. Using the parameters of the proton ring of HERA and those of the proposed linear e+e− collider (LC), we expect a luminosity of Lγp=1–2×1031 cm−2s−1, due to reasonable improvement of the proton beam. In a γp collider, the high energy γ beam is produced by the Compton backscattering of laser photons off the electron beam from the linear accelerator. In the case of the opposite choice of laser photon and electron beam helicities, the luminosity of γp collisions still exceeds 1031 cm−2s−1 up to a distance of 12 m between the conversion region and the collision point. We examine the physics research program for the HERA+LC γp collider proposal. The search for supersymmetric partners, leptoquark production and heavy quark investigations are considered in detail. The capacity of HERA+LC surpasses that of HERA and is comparable with the LC. Polarization facilities of the gamma and proton beams, and the clearer background compared to the hadron colliders, are stated as additional advantages of the proposed γp collider.
UNITARITY OF THE REALIZATION OF CONFORMAL SYMMETRY IN THE QUANTUM HALL EFFECT
Authors: GAITE JOSÉ
Published: October 2004

We study the realization of conformal symmetry in the quantum Hall effect (QHE) as part of the W∞ algebra. Conformal symmetry can be realized already at the classical level and implies the complexification of coordinate space. Its quantum version is not unitary. Nevertheless, it can be rendered unitary by a suitable modification of its definition which amounts to taking proper care of the quantum measure. The consequences of unitarity for the Chern-Simons theory of the QHE are also studied, showing the connection of nonunitarity with anomalies. Finally, we discuss the geometrical paradox of realizing conformal transformations as area-preserving diffeomorphisms.
CANONICAL QUANTIZATION OF NONLOCAL FIELD EQUATIONS
Authors: BARCI D.G. , OXMAN L.E. , ROCCA M.
Published: October 2004

We consistently quantize a class of relativistic nonlocal field equations characterized by a nonlocal kinetic term in the Lagrangian. We solve the classical nonlocal equations of motion for a scalar field and evaluate the on-shell Hamiltonian. The quantization is realized by imposing Heisenberg’s equation, which leads to the commutator algebra obeyed by the Fourier components of the field. We show that the field operator carries, in general, a reducible representation of the Poincaré group.

We also consider the Gupta-Bleuler quantization of a nonlocal gauge theory and analyze the propagators and the physical modes of the gauge field.
CONSTRUCTION OF GRAND UNIFIED MODELS BY DIMENSIONAL REDUCTION
Authors: RUDOLPH G. , VOLOBUEV I.P.
Published: October 2004

We discuss the problem of building grand unified models in the framework of the dimensional reduction method. In particular, we derive the bosonic sector of the flipped SU(5) grand unified model leading to correct spontaneous symmetry breaking and admitting the hierarchy of masses. For that purpose, we develop a new technique for constructing bases of generators adapted to reductions of representations of Lie algebras to subalgebras.
QUANTUM INTEGRABILITY OF NON-ULTRALOCAL MODELS THROUGH BAXTERIZATION OF QUANTIZED BRAIDED ALGEBRA
Authors: HLAVATÝ LADISLAV , KUNDU ANJAN
Published: October 2004

A scheme suitable for describing quantum non-ultralocal models, including supersymmetric ones, is proposed. Braided algebras are generalized to be used through Baxterization for constructing braided quantum Yang—Baxter equations. Supersymmetric and some known non-ultralocal models are derived in the framework of this approach. As further applications of the scheme, the construction of new quantum integrable non-ultralocal models, like mKdV and anyonic supersymmetric models including deformed anyonic superalgebra, is outlined.
THE WZW MODEL AS A DYNAMICAL SYSTEM ON AFFINE LIE GROUPS
Authors: CLUBOK K. , HALPERN M.B.
Published: October 2004

Working directly on affine Lie groups, we construct several new formulations of the WZW model. In one formulation WZW is expressed as a one-dimensional mechanical system whose variables are coordinates on the affine Lie group. When written in terms of the affine group element, this formulation exhibits a two-dimensional WZW term. In another formulation WZW is written as a two-dimensional field theory, with a three-dimensional WZW term, whose fields are coordinates on the affine group. On the basis of these equivalent formulations, we develop a translation dictionary in which the new formulations on the affine Lie group are understood as mode formulations of the conventional WZW formulation on the Lie group. Using this dictionary, we also express WZW as a three-dimensional field theory on the Lie group with a four-dimensional WZW term.
NONSTANDARD CONFORMAL FIELD THEORIES FROM THE b-c SYSTEMS ON GENERAL ALGEBRAIC CURVES
Authors: FERRARI F. , SOBCZYK J.
Published: October 2004

In this paper we develop an operator formalism for the b–c systems with conformalweight λ=1 defined on a general closed and orientable Riemann surface. The advantageof our approach is that the Riemann surface is represented as an affine algebraic curve.In this way it is possible to show that the b–c systems at higher genera are equivalentto nonstandard conformal field theories on the complex sphere. The amplitudes of theseconformal field theories, rigorously computed using simple normal ordering prescriptions,are single-valued on the algebraic curve and coincide with the correlation functions of theoriginal b–c systems. Besides the obvious applications in string theories and conformalfield theories, (the b–c systems at λ=1 are intimately related to the free scalar fieldtheory), the operator formalism presented here also sheds some light on the quantizationof field theories on Riemann surfaces.
KINEMATICS OF THE $t\bar t$ EVENTS IN W+ JETS AT CDF
Authors: BERETVAS ANDREW
Published: October 2004

We compare the CDF W+n≥3 jets data with predictions using the standard model.Herwig is used to simulate [Formula: see text] production and VECBOS is used to simulate QCD W+n≥3 jets. We look at four different data sets with [Formula: see text] content varying from 20% to 75%, andexamine several kinematic variables. We conclude that the data are consistent with thestandard model.
B FACTORY CONSTRAINTS ON ISOSINGLET DOWN QUARK MIXING, AND PREDICTIONS FOR OTHER CP-VIOLATING EXPERIMENTS
Authors: SILVERMAN DENNIS
Published: October 2004

In the main part of this paper we project forward to having B factory determinations of sin (2β) and sin (2α), for which we take several values. First, we use a joint χ2 analysis of CKM experiments to constrain CKM matrix elements in the standard model, and experiments on the angles a, β and γ, and on xs and null CP asymmetries. Then we invoke mixing to a new isosinglet down quark (as in E6) which induces FCNC’s that allow a Z0 mediated contribution to [Formula: see text] mixing and which brings in new phases. We then repeat the χ2 analysis, now including experimental constraints from FCNC’s as well, finding much larger ranges of prediction for the B factory. We then add projected B factory results on sin (2β) and sin (2α) and repeat both analyses. In (ρ, η) and (xs, sin (γ)) plots for the extra isosinglet down quark model, we find multiple regions that will require experiments on sin (γ) and/or xs to decide between, and possibly to effectively bound out the extra down quark contribution.
THE DECAY b→sγ IN THE 3–3–1 MODEL
Authors: AGRAWAL JYOTI , FRAMPTON PAUL H. , LIU JAMES T.
Published: October 2004

The 3–3–1 model, based on the gauge group SU (3)c× SU (3)L× U (1)X, makes a natural prediction of three generations based on anomaly cancellation. Since this is accomplished by incorporating the third family of quarks differently from the other two, it leads to potentially large flavor-changing neutral currents. A sensitive place to look for such effects is the flavor-changing b→sγ decay, which has recently been measured at CLEO. We compute this decay rate in the 3–3–1 model and compare it with that of the two-Higgs-doublet model, a subset of the full 3–3–1 model. We find that the additional 3–3–1 physics weakens the bound on the charged Higgs mass from MH+>290 GeV to MH+≳120 GeV .
SPECTRAL FUNCTION SUM RULE FOR GAUGE FIELDS
Authors: NISHIJIMA KAZUHIKO , TAKASE NOBORU
Published: October 2004

An exact evaluation of the wave function renormalization constant for the color gauge field is carried out because of the close relationship that it bears to color confinement. Since this constant can be expressed as an integral of the absorptive part or the spectral function of the gauge field propagator, the result takes the form of a sum rule for the spectral function. It should be emphasized that asymptotic freedom plays an essential role in its derivation.
TESTING VECTOR BOSON DOMINANCE OF ELECTROWEAK INTERACTIONS VIA e+e− ANNIHILATION INTO BOSON PAIRS
Authors: KABACHENKO V.V. , PIROGOV YU. F.
Published: October 2004

In the framework of the unified compositeness of leptons, quarks and Higgs bosons, supplemented with the hypothesis of the vector boson dominance of the SM gauge interactions, restrictions on the universal residual fermion–boson and boson–boson interactionsare investigated. Manifestations of the universal interactions in the W+W− and ZH boson pair production at the 2 TeV e+e− linear collider are studied. Definite signaturesof these interactions are exposed, and their relations to the nonstandard triple gaugeinteractions are considered. It is shown that the unified substructure could be tested atthe collider in these processes up to the compositeness scale [Formula: see text], which liesin the naturally preferred deca-TeV region. Importance of the optimal angular cutoffsand the polarized beams is found.
THERMAL TWO-POINT FUNCTION OF A HEAVY MUON IN HOT QED PLASMA WITHIN BLOCH NORDSIECK APPROXIMATION
Authors: TAKASHIBA K.
Published: October 2004

The thermal propagator of a heavy muon propagating in a hot QED plasma is examined within the Bloch–Nordsieck approximation, which is valid in the infrared region. Hard thermal loop resummation á la Arnold and Espinosa is taken into account for the photon line. It is shown that the heavy muon damping rate is finite.
A DISCRETIZED VERSION OF KALUZA–KLEIN THEORY WITH TORSION AND MASSIVE FIELDS
Authors: VIET NGUYEN AI , WALI KAMESHWAR C.
Published: October 2004

We consider an internal space of two discrete points in the fifth dimension of the Kaluza–Klein theory by using the formalism of noncommutative geometry — developed in a previous paper1 — of a spacetime supplemented by two discrete points. With the non-vanishing internal torsion two-form there are no constraints implied on the vielbeins. The theory contains a pair of tensor fields, a pair of vector fields and a pair of scalar fields. Using the generalized Cartan structure equation we are able to uniquely determine not only the Hermitian and metric-compatible connection one-forms, but also the nonvanishing internal torsion two-form in terms of vielbeins. The resulting action has a rich and complex structure, a particular feature being the existence of massive modes. Thus the nonvanishing internal torsion generates a Kaluza–Klein type model with zero and massive modes.
BARYONS AS THREE-FLAVOR SOLITONS
Authors: WEIGEL HERBERT
Published: October 2004

The description of baryons as soliton solutions of effective meson theories for three-flavor (up, down and strange) degrees of freedom is reviewed and the phenomenological implications are illuminated. In the collective approach the soliton configuration is equipped with baryon quantum numbers by canonical quantization of the coordinates describing the flavor orientation. The baryon spectrum resulting from exact diagonalization of the collective Hamiltonian is discussed. The prediction of static properties, such as the baryon magnetic moments and the Cabibbo matrix elements for semileptonic hyperon decays, are explored with regard to the influence of flavor symmetry breaking. In particular, the role of strange degrees of freedom in the nucleon is investigated for both the vector and axial vector current matrix elements. The latter are discussed extensively within the context of the proton spin puzzle. The influence of flavor symmetry breaking on the shape of the soliton is examined, and observed to cause significant deviations from flavor-covariant predictions on the baryon magnetic moments. Short range effects are incorporated by a chirally invariant inclusion of vector meson fields. These extensions are necessary for properly describing the singlet axial vector current and the neutron–proton mass difference. The effects of the vector meson excitations on baryon properties are also considered. The bound state description of hyperons and its generalization to baryons containing a heavy quark are illustrated. In the case of the Skyrme model a comparison is made between the collective quantization scheme and the bound state approach. Finally, the Nambu–Jona-Lasinio model is employed to demonstrate that hyperons can be described as solitons in a microscopic theory of the quark flavor dynamics. This is explained for both the collective and the bound state approaches to strangeness.
BEYOND THE LOW–GRIBOV THEOREM FOR HIGH ENERGY INTERACTIONS OF SCALAR AND GAUGE PARTICLES
Authors: ANTONOV E.N.
Published: October 2004

We obtain a generalization of the Low theorem for non-Abelian boson emission in collision of scalar and gauge vector particles and its extension to high energy collisions for small transverse momenta of produced particles. We demonstrate that in the case of particles with spin the direct extension of the Low formula to high energy is in contradiction with the correct amplitude factorization behavior. Consideration of different kinematical regions and use of methods of dual models allow us to separate contributions of intermediate excited states and standard spin corrections in the Low formulae. We show that the amplitude factorization occurs at high energy due to the contribution of the intermediate states which is additional to the gluon production amplitude for the scalar particle collision.
NONPERTURBATIVE QUANTUM GEOMETRY AND TORSION
Authors: MULLICK LIPIKA , BANDYOPADHYAY PRATUL
Published: October 2004

The relevance of torsion in nonperturbative quantum geometry is studied here from the viewpoint of the equivalence of the loop space to the space of gauge potentials modulo gauge transformations satisfying Mandelstam constraints. The topological feature associated with the gauge orbit space of a non-Abelian gauge theory when the topological θ term is introduced in the Lagrangian corresponds to a vortex line and the gauge orbit space appears to be multiply connected in nature. This has an implication in the loop space formalism, in the sense that the latter involves nonlocality and there is no way we could arrive at a corresponding continuum limit. In the gravity without the metric formalism of Capovilla, Jacobson and Dell, the θ term in the Lagrangian corresponds to torsion. This suggests that in the construction of a solution of functionals annihilated by the Hamiltonian constraint, any regularization procedure which destroys the gauge invariance of the loop space variables also destroys the topology of the gauge orbit space and the continuum limit can be achieved only by removing the vortex line. Thus the constraint equations of canonical quantization of gravity can be achieved only in the limit of torsion tending to zero. This provides the link between covariant and canonical quantization of gravity and demonstrates explicitly the role of the arrow of time in nonperturbative quantum geometry also when we take the gauge-invariant holonomy variables as the fundamental entity.
INTERACTING WESS–ZUMINO–NOVIKOV–WITTEN MODELS
Authors: SOLOVIEV OLEG A.
Published: October 2004

We study the system of two WZNW models coupled to each other via the current–current interaction. The system is proven to possess the strong/weak coupling duality symmetry. The strong coupling phase of this theory is discussed in detail. It is shown that in this phase the interacting WZNW models approach nontrivial conformal points along the renormalization group flow. The relation between the principal chiral model and interacting WZNW models is investigated.
RECENT DEVELOPMENTS IN μ+μ− COLLIDERS
Authors: BOGACZ S.A. , CLINE D.B.
Published: October 2004

New developments in crystal-based accelerator techniques for future μ+μ− colliders are outlined in the context of promising μ+μ− physics opportunities opening in the 250×250 GeV energy range (which will be discussed briefly). One of the novel schemes involves laser-driven high gradient (GeV/m) crystal acceleration combined with an effective crystal “cooler,” based on a stimulated radiation damping in a strain-modulated silicon crystal. The ultrastrong focusing environment of a crystal channel would provide effective transverse cooling without substantial blowup of the longitudinal momentum spread. An efficient cooling method is essential for enhancing the luminosity, while a high acceleration gradient would scale down the collider complex to a reasonable size. The conceptual design of a 250×250 GeV storage ring collider is outlined here. Two functional cells (accelerating and cooling) are described in more detail. The fundamental basis for this collider is that the μ± beams are not destroyed by either radiation like e± or hadronic interactions like [Formula: see text] thus allowing solid state (crystal) components to play a significant role. Assuming integration of two crucial functionalities (cooling and acceleration) into corresponding cells, such a collider would have a few thousands of various crystal components.
HUGE SPACE-DEPENDENT SYMMETRY IN THE LIGHTCONE GAUGE TWO-DIMENSIONAL QUANTUM GRAVITY
Authors: ABE MITSUO , NAKANISHI NOBORU
Published: October 2004

The lightcone gauge two-dimensional quantum gravity, i.e. the local version of Polyakov’s “induced” quantum gravity, is analyzed in the canonical operator formalism. An extremely huge x+-dependent symmetry algebra is found to exist in this model. Both Polyakov’s SL (2, R) current algebra and residual general coordinate invariance are very very tiny subalgebras of it.
THE ζ FUNCTION ANSWER TO PARITY VIOLATION IN THREE-DIMENSIONAL GAUGE THEORIES
Authors: GAMBOA SARAVÍ R.E. , ROSSINI G.L. , SCHAPOSNIK F.A.
Published: October 2004

We study parity violation in (2+1)-dimensional gauge theories coupled to massive fermions. Using the ζ function regularization approach we evaluate the ground state fermion current in an arbitrary gauge field background, showing that it gets two different contributions which violate parity invariance and induce a Chern–Simons term in the gauge field effective action. One is related to the well-known classical parity breaking produced by a fermion mass term in three dimensions; the other, already present for massless fermions, is related to peculiarities of gauge-invariant regularization in odd-dimensional spaces.
IMMERSIONS AND FOLDS IN STRING THEORIES OF GAUGE FIELDS
Authors: PAWELCZYK JACEK
Published: October 2004

A two-dimensional string model with dynamical cancellation of folds is considered. The action of the model contains the self-intersection number which is defined for surfaces immersed in 4D targets. The two additional variables are not dynamical and live on a compact manifold. In this sense the model is a compactification of a 4D theory. The cancellation forces the string θ angle to be equal π Candidates for string states are constructed. Some mathematical background is given.
sℓ(2)−4 WZW MODEL AS AN (N=4)-SUPERSYMMETRIC BOSONIC STRING WITH c=−2 MATTER
Authors: SEMIKHATOV A.M. , TIPUNIN I. YU.
Published: October 2004

We consider the sℓ(2) current algebra at level k=−4 when the sℓ(2) BRST operator is nilpotent. We formulate a spectral sequence converging to the cohomology of this BRST operator. At the second term in the spectral sequence, we observe the existence of an N=4 algebra. This algebra is generated in a c=−2 bosonic string whose BRST operator [Formula: see text] represents the next term in the spectral sequence. We realize the cohomology of the irreducible modules as [Formula: see text] primitives of theN=4 singular vectors and relate the latter to the Lian–Zuckerman states of c=−2 matter. The relation between the sℓ(2)−4 WZW model and the c=−2 bosonic string is established both at the level of BRST cohomology and at the level of an explicit operator construction. The relation of the N=4 algebra to the known symmetries of matter+gravity systems is also investigated.
ON ISING CORRELATION FUNCTIONS WITH BOUNDARY MAGNETIC FIELD
Authors: KONIK ROBERT , LECLAIR ANDRÉ , MUSSARDO GIUSEPPE
Published: October 2004

Exact expressions of the boundary state and the form factors of the Ising model are used to derive differential equations for the one-point functions of the energy and magnetization operators of the model in the presence of a boundary magnetic field. We also obtain explicit formulas for the massless limit of the one-point and two-point functions of the energy operator.
PHOTON STRUCTURE FUNCTIONS: TARGET PHOTON MASS EFFECTS AND QCD CORRECTIONS
Authors: MATHEWS PRAKASH , RAVINDRAN V.
Published: October 2004

We present a systematic analysis of the polarized and unpolarized processes e+e−→ e+e−X in the deep inelastic limit and study the effect of target photon mass (virtuality) on the photon structure functions. The effect of target photon virtuality manifests itself as new singly polarized structure functions, and also alters the physical interpretation of the unpolarized structure functions. The physical interpretation of these structure functions in terms of hadronic components is studied using the free field analysis. We also retrieve the real photon results in the limit where the virtuality goes to zero. Assuming factorization of the photon structure tensor, the relevant QCD corrections to the various twist 2 structure functions are evaluated.
WILSONIAN BLACK HOLE ENTROPY IN QUANTUM GRAVITY
Authors: ODINTSOV SERGEI D. , YOON YONGSUNG
Published: October 2004

Using the Wilsonian procedure (renormalization group improvement) we discuss the finite quantum corrections to black hole entropy in renormalizable theories. In this way, the Wilsonian black hole entropy is found for GUT’s (of asymptotically free form, in particular) and for the effective theory for the conformal factor aiming to describe quantum gravity in the infrared region. The off-critical regime (where the coupling constants are running) for the effective theory for the conformal factor in quantum gravity (with or without torsion) is explicitly constructed. The corresponding renormalization group equations for the effective couplings are found using the Schwinger-DeWitt technique for the calculation of the divergences of the fourth order operator.
INFLATIONARY COSMOLOGY FROM NONCOMMUTATIVE GEOMETRY
Authors: LIZZI F. , MIELE G. , SPARANO G. , MANGANO G.
Published: October 2004

In the framework of the Connes-Lott model based on noncommutative geometry, the basic features of a gauge theory in the presence of gravity are reviewed, in order to show the possible physical relevance of this scheme for inflationary cosmology. These models naturally contain at least two scalar fields, interacting with each other whenever more than one fermion generation is assumed. In this paper we propose to investigate the behavior of these two fields (one of which represents the distance between the copies of a two-sheeted space-time) in the early stages of the universe evolution. In particular the simplest Abelian model, which preserves the main characteristics of more complicate gauge theories, is considered and the corresponding inflationary dynamics is studied. We find that a chaotic inflation is naturally favored, leading to a field configuration in which no symmetry breaking occurs and the final distance between the two sheets of space-time is smaller the greater the number of e fold in each sheet.
PARAGENERALIZATION OF PEIERLS BRACKET QUANTIZATION
Authors: MOSTAFAZADEH ALI
Published: October 2004

A convenient formalism is developed to treat classical dynamical systems involving (p=2) parafermionic and parabosonic dynamical variables. This is achieved via the introduction of a parabracket which summarizes the paracommutation relations of the corresponding Green components in a unified manner. Furthermore, it is shown that Peierls quantization scheme may be applied to such systems provided that one uses the above-mentioned parabracket to express the quantum paracommutation relations. Application of the Peierls scheme also provides the form of the parafermionic and parabosonic kinetic terms in the Lagrangian.
LIGHT-QUARK MESON SPECTROSCOPY
Authors: BLÜM PETER
Published: October 2004

Light-quark meson spectroscopy provides a powerful tool for the study of QCD in the nonperturbative sector. There has been a lively experimental activity in this field over the last decade and different high-statistics results from large-acceptance spectrometer experiments have been published which have led to stimulating theoretical interpretations. Therefore it seems appropriate to review both the existing experimental results and the theoretical conclusions.
TWO-FORM GRAVITY AND THE GENERATION OF SPACE-TIME
Authors: KATSUKI MIYUKI , SUGAMOTO AKIO , NOJIRI SHIN’ICHI
Published: October 2004

In the framework of the two-form gravity, which is classically equivalent to the Einstein gravity, the one-loop effective potential for the conformal factor of metric is calculated in the finite volume and in the finite temperature by choosing a temporal gauge condition. There appears a quartically divergent term which cannot be removed by the renormalization of the cosmological term and we find there is only one nontrivial minimum in the effective potential. If the cutoff scale has a physical meaning, e.g. the Planck scale coming from string theory, this minimum might explain why the space-time is generated, i.e. why the classical metric has a nontrivial value.
MIRROR SYMMETRY AND STRING VACUA FROM A SPECIAL CLASS OF FANO VARIETIES
Authors: SCHIMMRIGK ROLF
Published: October 2004

Because of the existence of rigid Calabi-Yau manifolds, mirror symmetry cannot be understood as an operation on the space of manifolds with vanishing first Chern class. In this article I continue to investigate a particular type of Kähler manifolds with positive first Chern class which generalize Calabi-Yau manifolds in a natural way and which provide a framework for mirrors of rigid string vacua. This class comprises Fano manifolds of a special type which encode crucial information about ground states of the superstring. It is shown in particular that the massless spectra of (2, 2)-supersymmetric vacua of central charge ĉ=D crit can be derived from special Fano varieties of complex dimension D crit +2(Q−1), Q>1, and that in certain circumstances it is even possible to embed Calabi-Yau manifolds into such higher dimensional spaces. The constructions described here lead to new insight into the relation between exactly solvable models and their mean field theories on the one hand and their corresponding Calabi-Yau manifolds on the other. Furthermore it is shown that Witten’s formulation of the Landau-Ginzburg/Calabi-Yau relation can be applied to the present framework as well.
ANALYTIC FORMULATIONS OF THE DENSITY MATRIX RENORMALIZATION GROUP
Authors: MARTÍN-DELGADO MIGUEL A. , SIERRA GERMÁN
Published: October 2004

We present two new analytic formulations of the density matrix renormalization group (DMRG) method. In these formulations we combine the block renormalization group (BRG) procedure with the variational and Fokker-Planck methods. The BRG method is used to reduce the lattice size while the latter are used to construct approximate target states to compute the block density matrix. We apply our DMRG methods to the Ising model in a transverse field (ITF model) and compute several of its critical properties, which are then compared with the old BRG results.
THE CASE OF αs: Z VERSUS LOW ENERGIES OR, HOW NATURE SHOWS US NEW PHYSICS
Authors: SHIFMAN M.
Published: October 2004

The values of αs determined from low and high energy measurements are in irreconcilable contradiction with each other. The current status of the problem is critically reviewed. Consequences of the αs contradiction, in conjunction with other anomalies detected at the Z peak, are discussed. This article has been updated in accordance with experimental numbers reported at summer conferences.
THE SOLUTION OF THE d-DIMENSIONAL TWISTED GROUP LATTICES
Authors: LECHTENFELD OLAF , SAMUEL STUART
Published: October 2004

The general d-dimensional twisted group lattice is solved. The irreducible representations of the corresponding group are constructed by an explicit procedure. It is proven that they are complete. All matrix representation solutions to the quantum hyperplane equations are obtained.
A THEORY OF SPACE, TIME AND MATTER
Authors: WESSON P.S. , LEON J. PONCE DE , LIU H. , MASHHOON B. , KALLIGAS D. , EVERITT C.W.F. , BILLYARD A. , LIM P. , OVERDUIN J.
Published: October 2004

We unify the gravitational field with its source by considering a new type of 5D manifold in which space and time are augmented by an extra dimension which induces 4D matter. The classical tests of relativity are satisfied, and for solitons we obtain new effects which can be tested astrophysically. The canonical cosmological models are in agreement with observations, and we gain new insight into the nature of the big bang. Our inference is that the world may be pure geometry in 5D.