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1.
By considering the symmetries associated with baryon number and lepton number conservation as gauge symmetries, the underlying gauge symmetry of weak electromagnetic interactions is shown to be SU(2)
L
× U(1)× U(1) Baryon× U(1) Lepton. If right-handed currents exist on a par with the observed left-handed ones, then the full symmetry of electroweak interactions that emerges is SU(2) L× SU(2) R× U(1) Baryon× U(1) Lepton. These symmetries offer a rich spectrum of massive neutral gauge bosons, one of which is the massive neutral boson of the standard SU(2)
L
× U(1)
Y
model. 相似文献
2.
We discuss supersymmetric surface defects in compactifications of six-dimensional minimal conformal matter of types SU(3) and SO(8) to four dimensions. The relevant field theories in four dimensions are \(\mathcal{N}=1\) quiver gauge theories with SU(3) and SU(4) gauge groups, respectively. The defects are engineered by giving space-time-dependent vacuum expectation values to baryonic operators. We find evidence that in the case of SU(3) minimal conformal matter, the defects carry SU(2) flavor symmetry which is not a symmetry of the four-dimensional model. The simplest case of a model in this class is SU(3) SQCD with nine flavors, and thus the results suggest that this admits natural surface defects with SU(2) flavor symmetry. We analyze the defects using the superconformal index and derive analytic difference operators introducing the defects into the index computation. The duality properties of the four-dimensional theories imply that the index of the models is a kernel function for such difference operators. In turn, checking the kernel property constitutes an independent check of the dualities and the dictionary between six- dimensional compactifications and four-dimensional models. 相似文献
3.
We show that nonstrange baryon resonances can be classified according to multiplets of SU(4)⊗ O(3). We identify spectral regularities and degeneracies that allow us to predict the high-spin spectrum from 2 to 3GeV. 相似文献
4.
Semiclassical quantization of the SU(3)-skyrmion zero modes is performed by means of the collective coordinate method. The quantization condition known for SU(2) solitons quantized with SU(3) collective coordinates is generalized for SU(3) skyrmions with strangeness content different from zero. The quantization of the dipole-type configuration with large strangeness
content found recently is considered as an example and the spectrum and the mass splittings of the quantized states are estimated.
The energy and baryon number density of SU(3) skyrmions are presented in a form emphasizing their symmetry in different SU(2) subgroups of SU(3), and a lower bound for the static energy of SU(3) skyrmions is derived.
Zh. éksp. Teor. Fiz. 112, 1941–1958 (December 1997)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
5.
We suggest a quantum stabilization method for the SU(2) σ-model, based on the constant-cutoff limit of the cutoff quantization method developed by Balakrishna et al., which avoids the difficulties with the usual soliton boundary conditions pointed out by Iwasaki and Ohyama. We investigate
the baryon number B = 1 sector of the model and show that after the collective coordinate quantization it admits a stable soliton solution which
depends on a single dimensional arbitrary constant. We then study strong and electromagnetic properties of the Λ(1405) hyperon
in the bound-state approach to the SU(3)-soliton model for the hyperons, with SU(3)-symmetry breaking. We calculate the strong coupling constant g
Λ*NK;
, the magnetic moment of Λ*, the mean square radii, and the radiative decay amplitudes. Finally we compare the present results
with those obtained using other models and with the available empirical data. We show that there is a general qualitative
agreement between our results and the results of other models and available empirical data, except for the Λ*πΣ coupling,
which, as in the case of the complete Skyrme model, vanishes in the second-order approximation of the kaon fluctuations used
in this work. 相似文献
6.
We study here the Cabibbo enhanced charmed baryon decays in the SU(4) semidynamical model. The weak Hamiltonian 20″ + 15 + 45 + 45* can have the parity violating amplitude for charmed baryon
decays. Decay width and α for some modes are also calculated. 相似文献
7.
The effective electroweak Lagrange function appropriate to dynamic mass generation is obtained on the basis of the variational approach to the (super-)string inspired SU( 2) L × U(1) y × X U(1) E gauge field theory.This work was supported in part by the Ministry of Science and Higher Education under the contract CPBP 01.03.The authors would like to thank the Referee for a fruitful discussion. 相似文献
8.
A gauge theory with the gauge group U(1)× U(1)× SU(2)× SU(3)× SU(4) is shown to fit well into the generalized Kaluza scheme with eleven-dimensional space-time and its compact subspace S
2× S
5. A unified theory is obtained which exhibits some broken super-symmetric features ( N = 8). Our approach is dictated by phenomenological requirements. The appearance of three generations of leptons and six flavors of colored quarks follows naturally. Within our Lagrangian there appear several free parameters (coupling constants), but some relations between them may follow from the requirement of cancellation of divergencies.Temporarily at Dublin Institute for Advanced Studies, School of Theoretical Physics, 10 Burlington Rd., Dublin 4, Ireland. 相似文献
9.
The presence of domain walls separating regions of unbroken SU(2) L and SU(2) R is shown to provide necessary conditions for leptogenesis which converts later to the observed baryon asymmetry. The strength
of lepton number violation is related to the Majorana neutrino mass and hence related to current bounds on light neutrino
masses. Thus the observed neutrino masses and the baryon asymmetry can be used to constrain the scale of left-right symmetry
breaking. 相似文献
10.
The exotic baryon Θ +(1540 MeV) is visualized as an expected (iso) rotational excitation in the chiral soliton model. It is also argued as a pentaquark
baryon state in a constituent quark model with strong diquark correlations. I contrast these two points of view; observe the
similarities and differences between the two pictures. Collective excitation, the characteristic of chiral soliton model,
points toward small mixing of representations in the wake of SU (3) breaking. In contrast, constituent quark models prefer near ‘ideal’ mixing, similar to ω-φ mixing. 相似文献
12.
We used the local invariant chiral currents to obtain new integrable string equations for string WZW model type with SU(3) constant torsion. We solved Burgers equation of motion for first invariant current in. terms of Lambert function. We show
that string model with SU( n), n > 3 constant torsion does not integrable, because procedure of decomposition of non-primitive invariant chiral currents to
primitive currents is the procedure of introduction of infinite-dimensions matrix of second kind constraints in bi-Hamiltonian
approach to integrable systems. 相似文献
13.
本文证明了置换群CG系数和外积约化系数分别就是将任一SU m和SU n不可约基耦合成SU mn?SU m×SU n和SU m+n?SU m?SU n分类基的耦合系数,并给出了将SU mn?SU m×SU n和SU m+n?SU m?SU n分类基用Celfand基展开时计算展开系数的几种方法。给出了基本粒子中常用的SU 6?SU 3×SU 2和SU 8?SU 4×SU 2重子波函数。 相似文献
14.
We discuss the unification of gauge couplings within the framework of a wide class of realistic free-fermionic string models which have appeared in the literature, including the flipped SU(5), SO(6) × SO(4), and various SU(3) × SU(2) × U(1) models. If the matter spectrum below the string scale is that of the Minimal Supersymmetric Standard Model (MSSM), then string unification is in disagreement with experiment. We therefore examine several effects that may modify the minimal string predictions. First, we develop a systematic procedure for evaluating the one-loop heavy string threshold corrections in free-fermionic string models, and we explicitly evaluate these corrections for each of the realistic models. We find that these string threshold corrections are small, and we provide general arguments explaining why such threshold corrections are suppressed in string theory. Thus heavy thresholds cannot resolve the disagreement with experiment. We also study the effect of non-standard hypercharge normalizations, light SUSY thresholds, and intermediate-scale gauge structure, and similarly conclude that these effects cannot resolve the disagreement with low-energy data. Finally, we examine the effects of additional color triplets and electroweak doublets beyond the MSSM. Although not required in ordinary grand unification scenarios, such states generically appear within the context of certain realistic free-fermionic string models. We show that if these states exist at the appropriate thresholds, then the gauge couplings will indeed unify at the string scale. Thus, within these string models, string unification can be in agreement with low-energy data. 相似文献
15.
In an SU(6) grand unification model with eight quarks and eight leptons belonging to 15-plet and singlet representations, the symmetry is spontaneously broken by the sequence SU(6) SU(3)
c
× SU(2)× U(1)× U(1) SU(3)
c
× U(1). Fror two cases of symmetry breakings the effective weak neutral current coupling constants are compared with experiment. For the SU(3)
c
× SU(2)× U(1)× U(1)× SU(3)
c
× U(1) symmetry breaking, the coupling constants reproduce the Weinberg-Salam model with a small correction term. Agreement with the experimental mean values is improved with the correction term. Parity violation in atomic physics is also discussed. 相似文献
16.
The spectra of pentaquarks, some of them observed recently, are discussed within the topological soliton model and compared
with the simplified quark picture. The results obtained within the chiral soliton model depend to some extent on the quantization
scheme: rigid rotator, soft rotator, or bound state model. The similarity of the spectra of baryon resonances obtained within
the quark model and the chiral soliton model is pointed out, although certain differences take place as well, which require
careful interpretation. In particular, considerable variation of the strange antiquark mass in different SU(3) multiplets of pentaquarks is required to fit their spectra obtained from chiral solitons. Certain difference in the masses
of “good” and “bad” diquarks is required as well, in qualitative agreement with previously made estimates. The partners of
exotic states with different values of spin which belong to higher SU(3) multiplets have energy considerably higher than the states with the lowest spin, and this could be a point where the difference
from simple quark models is striking. The antiflavor excitation energies for multibaryons are estimated as well, and the binding
energies of gJ-hypernuclei and anticharm (antibeauty) hypernuclei are presented for several baryon numbers. Some deficiencies
are pointed out in the arguments in the literature against the validity of the chiral soliton approach and/or the SU(3) quantization models.
Based partly on the talks presented at the International Seminar on High Energy Physics Quarks-2004, Pushkinogorie, Russia,
May 24–30, 2004; International Workshop on Quantum Field Theory and High Energy Physics QFTHEP-04, Saint-Petersburg, Russia,
June 17–23, 2004, and Symposium of London Mathematical Society “Topological Solitons and their Applications,” Durham, UK,
August 2–12, 2004. A slightly reduced version of this paper is available as E-print HEP-PH/0507028.
The text was submitted by the author in English. 相似文献
17.
Until now there has been no empirical evidence for the existence of the Higgs particle, although the Higgs mechanism of symmetry breaking is very successful. We propose a scalar-tensor theory of gravity with the Higgs field of the SU(3)× SU(2)× U(1) standard model of the elementary particles as scalar field, which results finally in Einstein's gravity and in the SU(3)× SU(2)× U(1) standard model without any influence of the excited Higgs field. 相似文献
18.
In the SU(2)× SU(2) Skyrme model,one can treat the topological soliton-Skyrmion having baryon number B=1 as baryon.In this paper,we have used Skyrmion and anti-Skyrmion to construct a kind of composite soliton solution having baryon number B=0 but Hopf index H=1 and have found its mass depends on a dimensionless parameter p(0<p≤1).In addition,we have also discussed the quantization of the soliton and the probability of treating the quantized soliton as baryonium. 相似文献
19.
We study the spin- and flavour-dependent SU(6) violations in the baryon spectrum by means of a Gürsey-Radicati mass formula. The average energy of each SU(6) multiplet is described using the SU(6)-invariant interaction given by a hypercentral potential containing a linear and a hyper-Coulomb term. We show that the nonstrange- and strange-baryon masses are, in general, fairly well reproduced and moreover that the Gürsey-Radicati formula holds in a satisfactory way also for the excited states up to 2 GeV. 相似文献
20.
We suggest that breaking of SU(3) flavor symmetry mainly resides in the baryon wave functions while the charge operators have no (or only small) explicit symmetry-breaking components. We utilize the collective coordinate approach to chiral soliton models to support this picture. In particular we compute the g
A
/ g
V
ratios for hyperon beta-decay and the strangeness contribution to the nucleon axial current matrix elements and analyze their variation with increasing flavor symmetry breaking.Received: 30 September 2002, Published online: 22 October 2003PACS:
12.39.Dc Skyrmions - 12.39.Fe Chiral Lagrangians - 13.30.Ce Leptonic, semileptonic, and radiative decays - 14.20.Jn HyperonsH. Weigel: Heisenberg-Fellow; 相似文献
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