共查询到20条相似文献,搜索用时 31 毫秒
1.
Kenji Mohri 《Communications in Mathematical Physics》1999,202(3):669-699
We develop a method to analyze systematically the configuration space of a D-brane localized at the orbifold singular point
of a Calabi–Yau d-fold of the form ℂ
d
/Γ using the theory of toric quotients. This approach elucidates the structure of the K?hler moduli space associated with
the problem. As an application, we compute the toric data of the Γ-Hilbert scheme.
Received: 9 June 1998 / Accepted: 18 November 1998 相似文献
2.
S.É. Derkachov J.A. Gracey A.N. Manashov 《The European Physical Journal C - Particles and Fields》1998,2(3):569-579
We compute the anomalous dimensions of a set of composite operators which involve derivatives at four loops in in theory as a function of the operator moment . These operators are similar to the twist-2 operators which arise in QCD in the operator product expansion in deep inelastic
scattering. By regarding their inverse Mellin transform as being equivalent to the DGLAP splitting functions we explore to
what extent taking a restricted set of operator moments can give a good approximation to the exact four loop result.
Received: 12 May 1997 / Published online: 20 February 1998 相似文献
3.
O. Benhar S. Fantoni G.I. Lykasov 《The European Physical Journal A - Hadrons and Nuclei》1999,5(2):137-141
We propose a procedure to extrapolate the nuclear spectral function P(|k|E) obtained from nonrelativistic many-body theory to large values of three-momentum and removal energy. Our approach is based
on phenomenological information extracted from both soft hadron-nucleus interactions, in the regime where the proton inclusive
spectrum is dictated by Regge asymptotic, and deep-inelastic lepton-nucleus collisions. The extrapolated P(|k|E) is used to compute the semi-inclusive spectra of backward protons produced in electron-nucleus scattering.
Received: 1 December 1998 / Revised version: 19 January 1999 相似文献
4.
G. Parisi F. Slanina 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(4):603-611
We present a variational approach for directed polymers in D transversal dimensions which is used to compute the correction to the mean field theory predictions with broken replica symmetry.
The trial function is taken to be a symmetrized version of the mean-field solution, which is known to be exact for . We compute the free energy corresponding to that function and show that the finite-D corrections behave like D
-4/3
. It means that the expansion in powers of 1/D should be used with great care here. We hope that the techniques developed in this note will be useful also in the study
of spin glasses.
Receveid 19 May 1998 相似文献
5.
F. Ardalan A.H. Fatollahi K. Kaviani S. Parvizi 《The European Physical Journal C - Particles and Fields》1999,8(3):507-511
We suggest that the static configurations of M-theory may be described by the matrix regularization of the supermembrane
theory in static regime. We compute the long-range interaction between a M2-brane and an anti-M2-brane in agreement with the
11-dimensional supergravity result.
Received: 4 September 1998 / Published online: 15 April 1999 相似文献
6.
Kõta Yoshioka 《Communications in Mathematical Physics》1999,205(3):501-517
Recently, Minahan, Nemeschansky, Vafa and Warner computed partition functions for N = 4 topological Yang–Mills theory on rational
elliptic surfaces. In particular they computed generating functions of Euler characteristics of SU(2)-instanton moduli spaces. In mathematics, they are expected to coincide with those of Gieseker compactifications. In this
paper, we compute Euler characteristics of these spaces and show that our results coincide with theirs. We also check the
modular property of Z
SU
(2) and Z
SO
(3) conjectured by Vafa and Witten.
Received: 8 June 1998 / Accepted: 1 February 1999 相似文献
7.
Luen-Chau Li 《Communications in Mathematical Physics》1999,203(3):573-592
Given a classical r-matrix on a Poisson algebra, we show how to construct a natural family of compatible Poisson structures for the Hamiltonian
formulation of Lax equations. Examples for which our formalism applies include the Benny hierarchy, the dispersionless Toda
lattice hierarchy, the dispersionless KP and modified KP hierarchies, the dispersionless Dym hierarchy, etc.
Received: 10 February 1998 / Accepted: 9 December 1998 相似文献
8.
Giovanni Landi Fedele Lizzi Richard J. Szabo 《Communications in Mathematical Physics》1999,206(3):603-637
We construct a new gauge theory on a pair of d-dimensional noncommutative tori. The latter comes from an intimate relationship between the noncommutative geometry associated
with a lattice vertex operator algebra ? and the noncommutative torus. We show that the tachyon algebra of ? is naturally
isomorphic to a class of twisted modules representing quantum deformations of the algebra of functions on the torus. We construct
the corresponding real spectral triples and determine their Morita equivalence classes using string duality arguments. These
constructions yield simple proofs of the O(d,d;ℤ) Morita equivalences between d-dimensional noncommutative tori and give a natural physical interpretation of them in terms of the target space duality group
of toroidally compactified string theory. We classify the automorphisms of the twisted modules and construct the most general
gauge theory which is invariant under the automorphism group. We compute bosonic and fermionic actions associated with these
gauge theories and show that they are explicitly duality-symmetric. The duality-invariant gauge theory is manifestly covariant
but contains highly non-local interactions. We show that it also admits a new sort of particle-antiparticle duality which
enables the construction of instanton field configurations in any dimension. The duality non-symmetric on-shell projection
of the field theory is shown to coincide with the standard non-abelian Yang–Mills gauge theory minimally coupled to massive
Dirac fermion fields.
Received: 26 October 1998/ Accepted: 9 April 1999 相似文献
9.
We compute the normalisation factor for the large order asymptotics of perturbation theory for the self-avoiding manifold
(SAM) model describing flexible tethered (D-dimensional) membranes in d-dimensional space, and the ε-expansion for this problem. For that purpose, we develop the methods inspired from instanton
calculus, that we introduced in a previous publication (Nucl. Phys. B 534 (1998) 555), and we compute the functional determinant
of the fluctuations around the instanton configuration. This determinant has UV divergences and we show that the renormalized
action used to make perturbation theory finite also renders the contribution of the instanton UV-finite. To compute this determinant,
we develop a systematic large-d expansion. For the renormalized theory, we point out problems in the interplay between the limits ε→ 0 and d→∞, as well as IR divergences when ε=0. We show that many cancellations between IR divergences occur, and argue that the remaining
IR-singular term is associated to amenable non-analytic contributions in the large-d limit when ε=0. The consistency with the standard instanton-calculus results for the self-avoiding walk is checked for D=1. 相似文献
10.
We compute the BRST cohomology of the holomorphic part of the N= 1 string at arbitrary ghost and picture number. We confirm the expectation that the relative cohomology at non-zero momentum
consists of a single massless state in each picture. The absolute cohomology is obtained by an independent method based on
homological algebra. For vanishing momentum, the relative and absolute cohomologies both display a picture dependence – a
phenomenon discovered recently also in the relative Ramond sector of N= 1 strings by Berkovits and Zwiebach [1].
Received: 5 January 1998 / Accepted: 16 November 1998 相似文献
11.
Frobenius manifolds (solutions of WDVV equations) in canonical coordinates are determined by the system of Darboux–Egoroff
equations. This system of partial differential equations appears as a specific subset of the n-component KP hierarchy. KP representation theory and the related Sato infinite Grassmannian are used to construct solutions
of this Darboux–Egoroff system and the related Frobenius manifolds. Finally we show that for these solutions Dubrovin's isomonodromy
tau-function can be expressed in the KP tau-function.
Received: 1 September 1998 / Accepted: 7 March 1999 相似文献
12.
D.-U. Jungnickel C. Wetterich 《The European Physical Journal C - Particles and Fields》1998,2(3):557-567
We compare the linear meson model and chiral perturbation theory in next to leading order in the quark mass expansion. In
particular, we compute the couplings – of chiral perturbation theory as functions of the parameters of the linear model. They are induced by the exchange of scalar mesons. We use a phenomenological analysis of the effective vertices of the linear model in terms of pseudoscalar
meson masses and decay constants. Our results for the agree with previous phenomenological estimates.
Received: 21 April 1997 / Published online: 20 February 1998 相似文献
13.
J. Ellis G.K. Leontaris S. Lola D.V. Nanopoulos 《The European Physical Journal C - Particles and Fields》1999,9(3):389-408
Motivated by the Super-Kamiokande atmospheric neutrino data, we discuss possible textures for Majorana and Dirac neutrino
masses within the see-saw framework. There are two main purposes of this paper: first, to gain intuition into this area from
a purely phenomenological analysis, and second, to explore to what extent it may be realized in a specific model. We comment
initially on the simplified two-generation case, emphasizing that large mixing is not incompatible with a large hierarchy
of mass eigenvalues. We also emphasize that renormalization-group effects may amplify neutrino mixing, and we present semi-analytic
expressions for estimating this amplification. Several examples are then given of three-family neutrino mass textures, which
may also accommodate the persistent solar neutrino deficit, with different assumptions for the neutrino Dirac mass matrices.
We comment on a few features of neutrino mass textures arising in models with a U(1) flavour symmetry. Finally, we discuss the possible pattern of neutrino masses in a “realistic” flipped SU(5) model derived from string theory, illustrating how a desirable pattern of mixing may emerge. Both small- or large-angle
MSW solutions are possible, while a hierarchy of neutrino masses appears more natural than near-degeneracy. This model contains
some unanticipated features that may be relevant in other models also: The neutrino Dirac matrices may not be related closely
to the quark mass matrices, and the heavy Majorana states may include extra gauge-singlet fields.
Received: 6 November 1998 / Published online: 18 June 1999 相似文献
14.
We consider the finite-volume quantum n-vector anharmonic crystal in the large n limit and compute corrections to the corresponding Hartree–Fock system. In particular we prove the complete 1/n-asymptotic series of the free energy, the Gibbs canonical state, and the distributions of the displacement and squared displacement
fluctuation operators.
Received: 4 August 1998 / Accepted: 19 February 1999 相似文献
15.
C. Balzereit T. Hansmann T. Mannel B. Plümper 《The European Physical Journal C - Particles and Fields》1999,9(2):197-211
We compute the renormalization of the complete CKM matrix in the scheme and perform a renormalization group analysis of the CKM parameters. The calculation is simplified by studying only
the Higgs sector, which for the -function of the CKM matrix is at one loop the same as in the full Standard Model. The renormalization group flow including
QCD corrections can be computed analytically using the hierarchy of the CKM parameters and the large mass differences between
the quarks. While the evolution of the Cabibbo angle is tiny and increase sizably. We compare our results with the ones in the full Standard Model.
Received: 24 October 1998 / Revised version: 16 February 1999 / Published online: 15 April 1999 相似文献
16.
Ambresh Shivaji Subhadip Mitra Pankaj Agrawal 《The European Physical Journal C - Particles and Fields》2012,72(3):1922
In order to solve the hierarchy problem, several extra-dimensional models have received considerable attention. We have considered
a process where a Higgs boson is produced in association with a KK-graviton (G
KK) at the LHC. At the leading order, this process occurs through the gluon fusion mechanism gg→hG
KK via a quark loop. We compute the cross section and examine some features of this process in the ADD model. We find that the
quark in the loop does not decouple in the large quark-mass limit just as in the case of gg→h process. We compute the cross section of this process for the case of the RS model also. We examine the feasibility of this
process being observed at the LHC. 相似文献
17.
M. Barthélémy H. Orland 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(4):537-541
In this article, we propose a new method to compute the effective properties of non-linear disordered media. We use the fact
that the effective constants can be defined through the minimum of an energy functional. We express this minimum in terms
of a path integral allowing us to use many-body techniques. We obtain the perturbation expansion of the effective constants
to second order in disorder, for any kind of non-linearity. We apply our method to the case of strong non-linearities (i.e.
, where is fluctuating from point to point), and to the case of weak non-linearity (i.e.
where and fluctuate from point to point). Our results are in agreement with previous ones, and could be easily extended to other types
of non-linear problems in disordered systems.
Received: 13 May 1998 / Accepted: 27 July 1998 相似文献
18.
M. Alimohammadi A. Tofighi 《The European Physical Journal C - Particles and Fields》1999,8(4):711-717
We find a general expression for the free energy of generalized two-dimensional (2D) Yang-Mills theory in the strong () region for large N. We also show that in this region, the density function of Young tableau of these models is a three-cut problem. In the specific
model, we show that the theory has a third order phase transition, like the (YM) and models. We note problems for cases where , and at the end, examine the phase structure of the model for the region.
Received: 30 September 1998 / Revised version: 13 December 1998 / Published online: 15 April 1999 相似文献
19.
20.
The Dirac q-monopole connection is used to compute projector matrices of quantum Hopf line bundles for arbitrary winding number. The
Chern–Connes pairing of cyclic cohomology and K-theory is computed for the winding number −1. The non-triviality of this pairing is used to conclude that the quantum principal
Hopf fibration is non-cleft. Among general results, we provide a left-right symmetric characterization of the canonical strong
connections on quantum principal homogeneous spaces with an injective antipode. We also provide for arbitrary strong connections
on algebraic quantum principal bundles (Hopf–Galois extensions) their associated covariant derivatives on projective modules.
Received: Received: 4 September 1998 / Accepted: 16 October 1998 相似文献