共查询到20条相似文献,搜索用时 31 毫秒
1.
The fractional fermion number (charge) of (1+1)-dimensional Dirac field interacting with a scalar background field is investigated. By means of the correspondence principle in (1+1)-dimensional field theory,it is shown that only when the background field develops a solitvn with a node can the fractional fermion number be induced(node theorem).Consistently, a zero mode bound state of the fermion field should be present and responsible for the fractional charge as long as the soliton satisfies certain conditions (theorem of zero mode).We have also obtained the analytical expression of the vacuum charge distribution in the vicinitu of distorted reqion. 相似文献
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Dao-Jun Liu Ying-Li Zhang Xin-Zhou Li 《The European Physical Journal C - Particles and Fields》2009,60(3):495-500
We generalize the field theory of the global monopole to the Dirac–Born–Infeld (DBI) field and investigate the gravitational
property of a DBI global monopole in four-dimensional spherically symmetric spacetime. The coupled equations for the metric
and the DBI scalar field are solved asymptotically and numerically. It is found that, just as for a canonical global monopole,
the gravitational effect of the DBI global monopole is equivalent to that of a deficit solid angle in the metric plus a negative
mass at the origin. However, compared with a canonical global monopole, for the same false vacuum and symmetry-breaking scale,
a DBI global monopole has a relatively smaller core and a larger absolute value of effective mass. Thus, it can yield a larger
deflect angle when the light is passing by. Especially, when the scale of the warp factor is small enough, the effective mass
of a DBI global monopole does not depend apparently on the value of the false vacuum, which is qualitatively different from
that of a canonical global monopole. 相似文献
5.
V.A. Rubakov 《Nuclear Physics B》1982,203(2):311-348
In (V - A) theories, fermion number is broken in the presence of the 't Hooft-Polyakov magnetic monopole through the Adler-Bell-Jackiw anomaly. An exactly solvable zeroth-order approximation for evaluating Green functions of zero-angular-momentum fermions in the presence of a monopole is developed in the case of an SU(2) model with massless left-handed fermions. Within this approximation the density of the fermion-number breaking condensate is calculated. This density is found to be O(1), i.e. to be independent of the coupling constant and of the vacuum expectation value of the Higgs field. The corrections to the approximation are estimated. It is argued that the above effect can give rise to the strong baryon-number breaking in monopole-fermion interactions in SU(5) grand unified theory. 相似文献
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It is shown that the fermion number in a five-dimensional Kaluza-Klein theory (M4×S1) in which the fermion is interacting with a monopole field, is quantized in units of (ϕR)2 where the scalar ϕ is asymptotically constant andR is the radius of S1. 相似文献
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We discuss the intimate connection between the chaotic dynamics of a classical field theory and the instability of the one-loop
effective action of the associated quantum field theory. Using the example of massless scalar electrodynamics, we show how
the radiatively induced spontaneous symmetry breaking stabilizes the vacuum state against chaos, and we speculate that monopole
condensation can have the same effect in non-Abelian gauge theories. 相似文献
8.
S.A. Pritomanov 《Physics letters. A》1985,107(1):33-35
It is shown that under the action of an anisotropic gravitational field nonzero helicity appears in the vacuum state of the massless spinor field. In the hot universe theory it can be interpreted as an origin of baryon or lepton charges in the vacuum. The nonconservation of fermion number in the model is a result of the quantum disintegration of the “charged vacuum” in the process of evolution. The energy-momentum tensor of the created particles and vacuum polarization is calculated. 相似文献
9.
Wan-Yun Zhao 《The European Physical Journal C - Particles and Fields》1999,11(4):733-738
By perturbative calculations of the high-temperature ground-state axial vector current of fermion fields coupled to gauge
fields, an anomalous Chern–Simons topological mass term is induced in the three-dimensional effective action. The anomaly
in three dimensions appears just in the ground-state current rather than in the divergence of ground-state current. In the
Abelian case, the contribution comes only from the vacuum polarization graph, whereas in the non-Abelian case, contributions
come from the vacuum polarization graph and the two triangle graphs. The relation between the quantization of the Chern–Simons
coefficient and the Dirac quantization condition of magnetic charge is also obtained. It implies that in a (2+1)-dimensional
QED with the Chern–Simons topological mass term and a magnetic monopole with magnetic charge g present, the Chern–Simons coefficient must be also quantized, just as in the non-Abelian case.
Received: 7 April 1999 / Published online: 3 November 1999 相似文献
10.
《Physics letters. [Part B]》1988,205(4):451-454
The supermembrane classical solutions with non-trivial circle bundles, i.e. supermembrane monopole vacua, are derived. The hamiltonian of the fermion fluctuations about the monopole vacuum configuration is weakly hermitian, in contrast with the same problem in QED. The electrically charged and dyon analogues to the monopole vacua are also discussed. 相似文献
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A thin layer of the event horizon vicinity to the two-dimension black hole with a global monopole is considered as a system
of the Casimir type. The energy-momentum tensor is derived in Boulware vacuum, Hartle-Hawking vacuum and Unruh vacuum respectively.
The values are derived in the massless scalar field which satisfies the Dirichlet boundary conditions. Using the Wald's axioms,
the result is got which is the same with the one derived by the usual regularized methods. Meanwhile, the energy, energy density,
and pressure acting on the boundaries at the asymptotically flat background also are calculated too, and from the energy,
Casimir force is derived. The Casimir energy and Casimir force are compared respectively in the background before and after
radiation.
PACS: 42.50.Lc. 相似文献
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M. M. Islam 《Zeitschrift fur Physik C Particles and Fields》1992,53(2):253-262
The nonlinear σ-model with the Wess-Zumino action describes the nucleon as a soliton and incorporates the non-abelian chiral anomalies. Several studies have shown that the model works well except for the nucleon mass, which comes out consistently too large. We investigate this question beginning with the more general framework of the linear σ-model, which has besides a pseudoscalar meson sector, a fermion or quark sector, a scalar field and an interaction between the fermions via the scalar field. Using a path integral formulation, we express the fermion measure of the model as the product of a Jacobian and an invariant measure. Identifying this Jacobian as exp[iΓ wz] , we find that the model breaks up into two parts, when in the pseudoscalar meson sector the scalar field is replaced by its vacuum value. The pseudoscalar part of the model becomes the nonlinear σ-model with the Wess-Zumino actionΓ wz. The other part involves chiral fermions, the scalar field and their interaction. We continue this part back to the Minkowski space to determine its ground state and energy levels. We find that for a scalar field that vanishes at smallr, but rises sharply to its vacuum value at someR, the ground state energy of the interacting quark-scalar-field system can be lower than the ground state energy of the non-interacting quark system. This means the interaction between quarks and the scalar field can lead to a condensed ground state or vacuum and can reduce the overall energy of the system (a phase transition as in superconductivity). It is, therfore, not surprising that the nonlinear σ-model predicts too large a nucleon mass, since it implicitly assumes a normal non-interacting vacuum in the quark sector. Quarks are now quasiparticles that appear as excitations of the condensed vacuum. The nucleon structure that emerges from this investigation agrees fully with the phenomenological nucleon structure found from analysis of high energy elasticpp and \(\bar p\) p scattering at CERN ISR and SPS Collider. 相似文献
14.
Luiz C. L. Botelho 《International Journal of Theoretical Physics》2009,48(6):1701-1711
In this paper we intend to present some path-integral studies in the problem of confinement in the presence of fermionic and
scalar magnetic monopole fields through:
相似文献
1. | A Wilson Loop Path-Integral Evaluation associated to an effective second-quantized electromagnetic field generated by chiral abelian point-like monopole magnetic field current. |
2. | A Path-Integral Bosonization analysis of Quarks fields interacting with Kalb-Ramond fields considered as an effective Disorder Field Theory of a Q.C.D. vacuum of heavier monopoles. |
3. | Improvements on the Wilson Loops evaluations in the well-known ADHM Antonov-Ebert model for Cooper pairs of point-like fermionic magnetic monopoles. |
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In this paper, we utilize Nambu-Jona-Lasinio (NJL) mechanism to discuss the dynamical symmetry breaking for Weinberg-Salam model. In the NJL mechanism the symmetry breaking not only is determined by the potential ofscalar field V(φ) but also has important relation with condensate of the fermion pair (φφ). We find that the coefficient of quadric term of scalar field μ2 ≥ 0 can still cause symmetry breaking by virtue of (φφ) ≠ 0, and the vacuum expected value of scalar field obeys (φ) = (φφ), i.e., the order parameter which causes phase transition is the condensate of fermion pair (φφ). We also discuss the restoration problem of SU(2) × U(1) gauge symmetry breaking by the NJL mechanism at high temperatures. 相似文献
17.
A Bianchi I model of the Universe filled with interacting nonlinear spinor and scalar fields is studied within quantum geometrodynamics. Three types of interaction are considered: gradient, Yukawa, and axion ones. For massless fermion fields, the variables in the Wheeler – de Witt equation will separate. The solution can be interpreted using a two-component perfect liquid. One component corresponds to a massless scalar field, while the other – to a nonlinear spinor field. The interaction between the spinor and scalar fields can lead to elimination of singularity of the wave function. There is a possibility of existence of a discrete spectrum of the quantum Universe, as well as tunneling from the region with a rigorous equation of state to the region of the de Sitter vacuum. 相似文献
18.
In this paper a gauge theory with a classical solution corresponding to a magnetic monopole is quantised. By careful handling of the zero frequency modes it is shown that the monopole is capable of absorbing both momentum and charge. The angular momentum operator is considered and it is shown that if the original theory contains an isodoublet scalar field, the quantum excitations may be half odd integer eigenvalue eigenstates of this operator. 相似文献
19.
Kazuharu Bamba C. Q. Geng S. H. Ho W. F. Kao 《The European Physical Journal C - Particles and Fields》2012,72(4):1978
We investigate the generation of large-scale magnetic fields due to the breaking of the conformal invariance in the electromagnetic
field through the CPT-even dimension-six Chern–Simons-like effective interaction with a fermion current by taking account of the dynamical Kalb–Ramond
and scalar fields in inflationary cosmology. It is explicitly demonstrated that magnetic fields on 1 Mpc scale with the field
strength of ∼10−9 G at the present time can be induced. 相似文献
20.
ZHAO Guang-Da 《中国物理C(英文版)》1983,7(3):323-332
Assuming that leptons are composed of a heavy fermion and a heavy scalar boson and using Bethe-Salpeter equation, we conclude that in the non-relativistic limit the radius and , in particular, the anomalous magnetic moment of leptons can be sufficiently small provided that the interaction of the constituents is of vector type and that the fermion is much beavier than the scalar boson. Whereas the scalar type interaction can only give wavefunctions with large radius and anomalous magnetic moment. 相似文献