May 1993 arXiv papers — page 6

Dan Radu Grigore

A geometric global formulation of the higher-order Lagrangian formalism for systems with finite number of degrees of freedom is provided. The formalism is applied to the study of systems with groups of Noetherian symmetries.

A. A. Bytsenko, E. Elizalde, S. D. Odintsov

The renormalization group method is employed to study the effective potential in curved spacetime with torsion. The renormalization-group improved effective potential corresponding to a massless gauge theory in such a spacetime is found and in this way a generalization of Coleman-Weinberg's approach corresponding to flat space is obtained. A method which

Q. P. Xu, A. N. Kamal

We suggest that, similar to the many applications of chiral effective Lagrangian made recently to semileptonic decays of heavy hadrons involving Goldstone bosons, chiral symmetry can also be applied to many-body nonleptonic decays of heavy hadrons. As examples we establish the chiral effective Hamiltonian for some typical many-body nonleptonic decays of bott

L. Lavoura

In a recent paper on SU(16) grand unification, because of the presence of intermediate-energy gauge groups containing products of U(1) factors which are not orthogonal among themselves, the renormalization-group treatment has a few small errors. I correct it. I emphasize that one should not switch gauge couplings at the various thresholds. It is easier, and

K. Langfeld, L. v. Smekal, H. Reinhardt

The effective potential for the local composite operator $ϕ^{2}(x)$ in $λϕ^{4}$-theory is investigated at finite temperature in an approach based on path-integral linearisation of the $ϕ^4 $-interaction. At zero temperature, the perturbative vacuum is unstable, because a non-trivial phase with a scalar condensate $\langle ϕ^{2} \rangle _{0}$ has lower effect

Eung Jin Chun, Hang Bae Kim, Jihn E. Kim

It is suggested that the axino mass in the 1 MeV region and gravitino mass in the eV region can provide an axino lifetime of order of the time of photon decoupling. In this case, some undecayed axinos act like cold dark matters and some axino decay products (gravitinos and hot axions) act like hot dark matters at the time of galaxy formation.

S. Yu. Khlebnikov

We consider isospin correlations of pions produced in a relativistic nuclear collision, using an effective theory of the chiral order parameter. Our theory has (1+1) Lorentz invariance as appropriate for the central rapidity region. We argue that in certain regions of space correlations of the chiral order parameter are described by the fixed point of the (1

Sourendu Gupta, A. Irbaeck, M. Ohlsson

{}From a finite-size scaling (FSS) theory of cumulants of the order parameter at phase coexistence points, we reconstruct the scaling of the moments. Assuming that the cumulants allow a reconstruction of the free energy density no better than as an asymptotic expansion, we find that FSS for moments of low order is still complete. We suggest ways of using thi

J. Adler, C. Holm, W. Janke

Although there is now a good measure of agreement between Monte Carlo and high-temperature series expansion estimates for Ising ($n=1$) models, published results for the critical temperature from series expansions up to 12{\em th} order for the three-dimensional classical Heisenberg ($n=3$) and XY ($n=2$) model do not agree very well with recent high-precisi

A. A. Aligia

A model consisting of oxygen-occupied and -vacant chains is considered, with repulsive first and second nearest-neighbor interactions V1 and V2, respectively. The statistical mechanics and the diffraction spectrum of the model is solved exactly and analytically with the only assumption V1 >> V2. At temperatures T ~ V1 only a broad maximum at (1/2,0,0) is pre

Alfred S. Goldhaber, Hsiang-Nan Li, Rajesh R. Parwani

Recent results on the vacuum polarization induced by a thin string of magnetic flux lead us to suggest an analogue of the Copenhagen `flux spaghetti' QCD vacuum as a possible mechanism for avoiding the divergence of perturbative QED, thus permitting consistent completion of the full, nonperturbative theory. The mechanism appears to operate for spinor, bu

Ka Lok Ng, Kin-Wang Ng

The anisotropy and polarization of the cosmic microwave background radiation (CMBR) induced by the scalar and tensor metric perturbations are computed in the long-wavelength limit. It is found that the large-scale polarization of CMBR induced by the decaying tensor mode can reach a few percents. This is different from the scalar or inflation-induced tensor m

Alexei Yu. Smirnov, David N. Spergel, John N. Bahcall

The original \bnum -(or $\barν_τ$-) energy spectrum from the gravitational collapse of a star has a larger average energy than the spectrum for \bnue since the opacity of \bnue exeeds that of \bnum (or $ν_τ$). Flavor neutrino conversion, \bnue $\leftrightarrow$ \bnum, induced by lepton mixing results in partial permutation of the original \bnue and \bnum spe

Kirti Joshi

In this paper we generalize the classical Noether-Lefschetz Theorem to arbitrary smooth projective threefolds. Let $X$ be a smooth projective threefold over complex numbers, $L$ a very ample line bundle on $X$. Then we prove that there is a positive integer $n_0(X,L)$ such that for $n \geq n_0(X,L)$, the Noether-Lefschetz locus of the linear system $H^0(X,L^

Markus A. Luty, Martin White

We consider the predictions of chiral perturbation theory for $SU(3)$ breaking in the axial vector form factor $g_1$ measured in semileptonic hyperon decays. We confirm that if only octet baryon intermediate states are included, the non-analytic corrections are $\sim 100\%$. These corrections are dominated by an $SU(3)$-symmetric wavefunction renormalization

L. Bonora, C. S. Xiong

We discuss the integrable hierarchies that appear in multi--matrix models. They can be envisaged as multi--field representations of the KP hierarchy. We then study the possible reductions of this systems via the Dirac reduction method by suppressing successively one by one part of the fields. We find in this way new integrable hierarchies, of which we are ab

P. Butera, M. Comi, A. J. Guttmann

High temperature series expansions of the spin-spin correlation function for the plane rotator (or XY) model on the sc lattice are extended by three terms through order $\beta^{17}$. Tables of the expansion coefficients are reported for the correlation function spherical moments of order $l=0,1,2$. Our analysis of the series leads to fairly accurate estimate

Géza Fülöp

The Ashtekar-Renteln Ansatz gives the self-dual solutions to the Einstein equation. A direct generalization of the Ashtekar-Renteln An\-satz to N=1 supergravity is given both in the canonical and in the covariant formulation and a geometrical property of the solutions is pointed out. (Changes: the covariant formulation and some comments about a wave function

Avshalom C. Elitzur, Lev Vaidman

A novel manifestation of nonlocality of quantum mechanics is presented. It is shown that it is possible to ascertain the existence of an object in a given region of space without interacting with it. The method might have practical applications for delicate quantum experiments.

A. Yu. Boldin, V. V. Dmitrieva, S. S. Safin, R. A. Sharipov

Newtonian dynamical systems which accept the normal shift on an arbitrary Riemannian manifold are considered. For them the determinating equations making the weak normality condition are derived. The expansion for the algebra of tensor fields is constructed.

Viqar Husain

A 3d generally covariant field theory having some unusual properties is described. The theory has a degenerate 3-metric which effectively makes it a 2d field theory in disguise. For 2-manifolds without boundary, it has an infinite number of conserved charges that are associated with graphs in two dimensions and the Poisson algebra of the charges is closed. F

Per Elmfors, Bo-Sture Skagerstam, David Persson

The QED effective action at finite temperature and density is calculated to all orders in an external homogeneous and time-independent magnetic field in the weak coupling limit. The free energy, obtained explicitly, exhibit the expected de\ Haas -- van\ Alphen oscillations. An effective coupling at finite temperature and density is derived in a closed form a

Neil Marcus, Yaron Oz

We solve the equations of motion of the tachyon and the discrete states in the background of Witten's semiclassical black hole and in the exact 2D dilaton-graviton background of Dijkgraaf et al. We find the exact solutions for weak fields, leading to conclusions in disagreement with previous studies of tachyons in the black hole. Demanding that a state i

Yakir Aharonov, Lev Vaidman

It is shown that it is possible to measure the Schrödinger wave of a single quantum system. This provides a strong argument for associating physical reality with a quantum state of a single system in sharp contrast with the usual approach in which the physical meaning of a quantum state is related only to an ensemble of identical systems. An apparent paradox

Eric Braaten, Kingman Cheung, Tzu Chiang Yuan

The dominant production mechanism for ${\bar b} c$ bound states in high energy processes is the production of a high energy ${\bar b}$ or $c$ quark, followed by its fragmentation into the ${\bar b} c$ state. We calculate the fragmentation functions for the production of the S-wave states $B_c$ and $B_c^*$ to leading order in the QCD coupling constant. The fr

Naoya Hata, Paul Langacker

We consider the Earth effect in the MSW analysis of the Homestake, Kamiokande, GALLEX, and SAGE solar neutrino experiments. Using the time-averaged data and assuming two-flavor oscillations, the large-angle region of the combined fit extends to much smaller angles (to $\sin^22θ\simeq 0.1$) than when the Earth effect is ignored. However, the additional constr

Mauro Anselmino, Stefano Forte

We discuss the relationship of the forward matrix element of the operator $\barψψ$, related to the so-called sigma term, to the quark number. We show that in the naive quark model in the canonical formalism these quantities coincide in the limit of small average quark momenta. In the QCD parton model defined through light-front quantization this result is pr

A. Jakovác, A. Patkós

Using the 1-loop reduced 3D action of the Abelian Higgs-model we discuss the order of its finite temperature phase transition. A two-variable saddle point approximation is proposed for the evaluation of the effective potential. The strength of the first order case scales like \sim e^{3-6}. Analytic asymptotic weak coupling and numerical small coupling soluti

Karl Jansen, Julius Kuti, Chuan Liu

The triviality Higgs mass bound is studied with a higher derivative regulator in the spontaneously broken phase of the four dimensional O(4) symmetric scalar field theory with quartic self-interaction. The phase diagram of the O(4) model is determined in a Monte Carlo simulation which interpolates between the hypercubic lattice regulator and the higher deriv

Karl Jansen, Julius Kuti, Chuan Liu

A higher derivative term is introduced in the kinetic energy of the Higgs Lagrangian in the minimal Standard Model. A logically consistent and {\it finite} field theory is obtained when some excitations of the Higgs field are quantized with indefinite metric in the Hilbert space. The Landau ghost phenomenon of the conventional triviality problem is replaced

Jorma Louko

A finite dimensional system with a quadratic Hamiltonian constraint is Dirac quantized in holomorphic, antiholomorphic and mixed representations. A unique inner product is found by imposing Hermitian conjugacy relations on an operator algebra. The different representations yield drastically different Hilbert spaces. In particular, all the spaces obtained in

K. L. Ng

The gravitational properties of the neutrino is studied in the weak field approximation. By imposing the hermiticity condition, CPT and CP invariance on the \em tensor matrix element, we shown that the allowed gravitational form factors for Dirac and Majorana neutrinos are very different. In a CPT and CP invariant theory, the \em tensor for a Dirac neutrino

L Biferale, A Crisanti, M Falcioni, A Vulpiani

In this letter we study chaotic dynamical properties of an asymmetrically coupled one-dimensional chain of maps. We discuss the existence of coherent regions in terms of the presence of defects along the chain. We find out that temporal chaos is instantaneously localized around one single defect and that the tangent vector jumps from one defect to another in

Russell W. Anderson, Avidan U. Neumann, Alan S. Perelson

A Cayley tree model of idiotypic networks that includes both B cell and antibody dynamics is formulated and analyzed. As in models with B cells only, localized states exist in the network with limited numbers of activated clones surrounded by virgin or near-virgin clones. The existence and stability of these localized network states are explored as a functio

M. Gross

We prove that up to birational equivalence, there exists only a finite number of families of Calabi-Yau threefolds (i.e. a threefold with trivial canonical class and factorial terminal singularities) which have an elliptic fibration to a rational surface. This strengthens a result of B. Hunt that there are only a finite number of possible Euler characteristi

Rodolfo Gambini, Leonardo Setaro

We introduce a path-dependent hamiltonian representation (the path representation) for SU(2) with fermions in 3 + 1 dimensions. The gauge-invariant operators and hamiltonian are realized in a Hilbert space of open path and loop functionals. We obtain two new types of Mandelstam identities one that connects open path operators with loop operators and other in

Chang-Pu Sun

In this paper the evolution of a quantum system drived by a non-Hermitian Hamiltonian depending on slowly-changing parameters is studied by building an universal high-order adiabatic approximation(HOAA) method with Berry's phase ,which is valid for either the Hermitian or the non-Hermitian cases. This method can be regarded as a non-trivial generalizatio

Yu. A. Kubyshin, V. O. Malyshenko, D. Marin Ricoy

Invariant connections with torsion on simple group manifolds $S$ are studied and an explicit formula describing them is presented. This result is used for the dimensional reduction in a theory of multidimensional gravity with curvature squared terms on $M^{4} \times S$. We calculate the potential of scalar fields, emerging from extra components of the metric

Carlo Rovelli

We show that the Hilbert space basis that defines the Ponzano-Regge- Turaev-Viro-Ooguri combinatorial definition of 3-d Quantum Gravity is the same as the one that defines the Loop Representation. We show how to compute lengths in Witten's 3-d gravity and how to reconstruct the 2-d geometry from a state of Witten's theory. We show that the non-degene

Leonardo Castellani, Marco A. R-Monteiro

The Cartan-Maurer equations for any $q$-group of the $A_{n-1}, B_n, C_n, D_n$ series are given in a convenient form, which allows their direct computation and clarifies their connection with the $q=1$ case. These equations, defining the field strengths, are essential in the construction of $q$-deformed gauge theories. An explicit expression $\om ^i\we \om^j=

A. Giveon, E. Rabinovici, A. A. Tseytlin

We discuss solutions of the heterotic string theory which are analogous to bosonic and superstring backgrounds related to coset conformal field theories. A class of exact `left-right symmetric' solutions is obtained by supplementing the metric, antisymmetric tensor and dilaton of the superstring solutions by the gauge field background equal to the genera

Lajos Diosi

In this short note we show that for a Markovian open quantum system it is always possible to construct a unique set of perfectly consistent Schmidt paths, supporting quasi-classicality. Our Schmidt process, elaborated several years ago, is the $Δt\to 0$ limit of the Schmidt chain constructed very recently by Paz and Zurek.