共查询到20条相似文献,搜索用时 31 毫秒
1.
The mechanism of baryon decay via monopoles is analyzed. For this purpose we quantize isodoublet fermion fields in the presence of a 't Hooft-Polyakov monopole. When the electromagnetic interactions are switched off, we find a condensation of a fermion pair \(\bar \psi _ - ^{(i)} \gamma ^0 \gamma ^5 \psi _ + ^{(i)} \) as well as that of \(\bar \psi _ - ^{(i)} \gamma ^0 \gamma ^5 \psi _ + ^{(i)} \bar \psi _ + ^{(j)} \gamma ^0 \gamma ^5 \psi _ - ^{(j)} \) . Here, the indices ± stand for the electric charge and (i,j) for the flavour. Hence, the charge symmetry is spontaneously broken. However, when the Coulomb interactions are switched on, it is proved that all fermion condensates carrying non-zero electric charges are removed; the condensates carrying zero electric charge, which induce baryon decay in the standardSU (5) model, are not removed by switching on the Coulomb interactions. In these analyses, the key element is the charge mixing boundary condition imposed on the fermion wave-function at the monopole center; the chiral anomaly does not play any role. 相似文献
2.
Th. Ohrndorf 《Nuclear Physics B》1985,260(2):333-349
The implications of the finite size of the 't Hooft-Polyakov monopole for the Callan-Rubakov effect are studied. The chirality-violating condensate is derived without imposing a boundary condition on the fermion field at the origin. Finite-distance corrections to the condensate are worked out. 相似文献
3.
We show that for a fermion in a bounded background potential in a finite box, eigenvalues of the total charge are independent
of whether the potential is solitonic and depend only on the boundary condition: half-odd integral or integral for charge
conjugation (C) invariant boundary conditions and an arbitrary fraction forC non-invariant boundary conditions. Fractional fermion numbers for infinite space Jackiw-Rebbi and Goldstone-Wilczek Hamiltonians
are reproduced in finite space by using boundary conditions different from the periodic ones of Rajaraman and Bell. 相似文献
4.
The Hamiltonian of a radial equation is defined on a half-line,and there is a close relation between its hermitian and the boundary condition of the wave functions at the origin.If the wave functions are nonvanishing and convergent at the origin,the Hamiltonian has a one-parameter family of self-adjoint extensions which are related with the vanishness of the radial probability current at the origin.In this paper the problem on the hermitian of the Hamiltonian of a radial equation is studied systematically.Some methods for determining the parameter for the fermion moving in the magnetic monopole field are discussed. 相似文献
5.
In monopole-fermion dynamics, the boundary condition which is responsible for baryon number non-conservation also violates electric and color hypercharge conservation. We show by detailed calculations that actually the latter conservation laws are dynamically restored. It is shown that for a finite size monopole, there is a small but finite amplitude for the monopole ground state to make a virtual transition into a state containing a dyon and some fermions carrying equal and opposite charge as that of the dyon. But the amplitude for this state to make a virtual transition to a state carrying a net total charge is identically zero. The monopole ground state, as a result, is an eigenstate of electric charge even in the presence of massless fermions. We also calculate the four-body charge and chirality conserving but baryon number violating condensates, which exist independently of the existence of the anomaly and hence persist even in the presence of more generations of massless fermions. 相似文献
6.
We consider a fermion of chargee confined to a spherical bag with a Dirac monopole of strengthg at its centre. We find that the boundary conditions making the lowest angular momentum hamiltonian self-adjoint are characterized
by a unitary matrixU, and the corresponding vacuum charge has a fractional part 2|eg|α/π where detU = -exp (2iα). Boundary conditions for conservation of helicity,CP, CT andPT are displayed. We demonstrate the possibility of a fractionally charged dyon whose interaction with a fermion conserves helicity.
We also show thatthe simultaneous validity of helicity, CP, CT and PT requires integer vacuum charge. 相似文献
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9.
In an SU(2) spontaneously broken gauge theory with a Higgs triplet, the mass effect of an iosspin 1/2 fermion on the fernlion-nlonopole bound states is discussed. It is shown that when the direct coupling betrveen fermion and Higgs field approaches zero, but the Dirac mass remalns finiteness, the necessary condition of the fermion-monopole bound state cannot be satisfied. This result means that the Rubakov effect is absent for SU(2) monopole because of the Dirac mass. 相似文献
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11.
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
12.
We show that, in four dimensional field-theoretical model containing fermion field and background isovector scalar field, an induced magnetic monopole field emerges as a result of adiabatical evolution of the scalar field. For the corresponding Dirac Hamiltonian the degenerate eigenmodes of the vacuum are known to exist. The effective system is then shown to give fractional fermion number on vacuum. In the present approach the magnetic monopole field is not quite essentially given as a topologically non-trivial external field but induced as the result of adiabatic evolution of a scalar field. 相似文献
13.
《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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M. Faber A. N. Ivanov N. I. Troitskaya 《Zeitschrift fur Physik C Particles and Fields》1997,74(4):721-726
We propose a model where a condensate of monopole-antimonopole pairs leads to confinement. Magnetic monopoles are considered as massless fermion fields interacting via local four-monopole interaction of the Nambu-Jona-Lasinio kind leading to monopole condensation. Condensation of magnetic monopole currents and any derivative of them are obtained. It is shown that the bosonized version of this Monopole Nambu-Jona- Lasinio (MNJL) model is reducing to London’s theory of dual superconductivity within Dirac’s extension of Maxwell’s Electrodynamics. The affinity of the MNJL-model with Compact Quantum Electrodynamics is discussed. 相似文献
16.
Joseph N Ginocchio 《Annals of Physics》1980,126(1):234-276
A schematic Hamiltonian with a pairing interaction plus a quadrupole-quadrupole interaction between nucleons is presented. It is shown that all the states of the fermion system can be classified according to the number of nucleons u not coupled to coherent monopole or quadrupole pairs. The states with u = 0 are shown to have a one-to-one correspondence to the states of the interacting boson model. The spectra for these states are derived analytically for various limits of the pairing strength and the quadrupole strength. Analytical forms for the matrix elements of operators are derived for these limits. The operators in fermion space are mapped onto boson operators. The matrix elements of operators in the fermion space are shown to be equal to matrix elements of the boson operators multiplied by analytical Pauli factors which are state dependent. The two-nucleon transfer strength is calculated in two limits and is compared to experimental values. 相似文献
17.
We derive the formal equivalence of a free massless two-dimensional theory and a free massless two-dimensional boson theory constructed from the bilinear products of the self-same fermion theory. The sense of this equivalence is investigated. Using a box normalization, it is found that the fermion states are Glauber coherent states of bosons, where the boson vacuum is the ground state of the charge sector corresponding to the given fermion state. The massless boson is the Goldstone boson and the degenerate vacua are the ground states of the various charge sectors. A complete operator identity between fermion and boson operators can be obtained, but to do this an additional boson operator must be introduced which cannot be defined in terms of bilinear products of the fermion operators. Doing this makes the charge spectrum continuous. 相似文献
18.
By showing that the radially reduced QCD of s-wave fermions outside the core of a GUT monopole can be treated in a way analogous to 't Hofft's QCD2 in the large Nclimit, we are able to give a complete QFT treatment of all the relevant long-range gauge fields outside the monopole core. We prove that the original cluster argument for the existence of baryon number violating fermion “condensates” around the core, gives in fact, the correct result, despite the neglect of QCD strong interactions, which prevent the propagation of isolated quarks. We discuss briefly how a complete computational framework for a monopole induced hadron-lepton transition might be derived. 相似文献
19.
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
20.
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