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Dennis Nemeschansky 《Nuclear Physics B》1984,234(2):379-401
Supersymmetric grand unified models with a sliding singlet are considered. We review the argument that the sliding does not work in models with large supersymmetry breaking. Then we consider the possibility of using a sliding singlet with low-energy supersymmetry breaking. A number of problems with such a program are noted and illustrated in simple examples. Using the experience gained from these examples a realistic model is constructed and analyzed. 相似文献
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When considering strangelets at finite temperature it is important to obey the constraint that any observed state must be color singlet. This constraint results in an increase in strangelet masses as calculated at fixed entropy per baryon. We use the color singlet partition function for an MIT bag, derived using the group theoretical projection method, to calculate strangelet masses. Mean shell effects are included in a liquid drop model, by using a density of states obtained from the multiple reflection expansion. Another important effect of the color singlet restriction, namely many orders of magnitude suppression of thermal nucleation of quark-gluon plasma in collisions, will also briefly be described. 相似文献
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Hidetoshi Fukuyama 《Hyperfine Interactions》1997,104(1-4):17-21
The spin‐gap phenomenon is a key characteristic of high Tc superconducting cuprates, whose experimental results are summarized and discussed in the context of the slave‐boson mean
field theory of the extended t–J model. It is seen that there exists satisfactory agreement between theory and experiments
in bilayer cuprates. As regards the apparent absence of the spin‐gap in single layer La2-xSrxCuO4 (LSCO), the possible roles played by disorder have been pointed out in view of the recent neutron scattering experiment on
other spin singlet systems, the spin‐Peierls CuGeO3 and two‐leg ladders.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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We have investigated spin singlet Mott states of spin-one bosons with antiferromagnetic interactions. These spin singlet states do not break rotational symmetry and exhibit remarkably different macroscopic properties compared with nematic Mott states of spin-one bosons. We demonstrate that the dynamics of spin singlet Mott states is fully characterized by even- or odd-class quantum dimer models. The difference between spin singlet Mott states for even and odd numbers of atoms per site can be attributed to a selection rule in the low energy sectors of on-site Hilbert spaces; alternatively, it can also be attributed to an effect of Berry’s phases on bosonic Mott states. We also discuss evidence for spin singlet quantum condensate of spin-one atoms. Our main finding is that in a projected spin singlet Hilbert space, the low energy physics of spin-one bosons is equivalent to that of a Bose-Hubbard model for spinless bosons interacting via Ising gauge fields. The other major finding is spin-charge separation in some one-dimensional Mott states. We propose charge-e spin singlet superfluid for an odd number of atoms per lattice site and charge-2e spin singlet superfluid for an even number of atoms per lattice site in one-dimensional lattices. All discussions in this article are limited to integer numbers of bosons per site. 相似文献
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Controlling the pump beam transverse profile in multimode Hong-Ou-Mandel interference, we generate a "localized" two-photon singlet state, in which both photons propagate in the same beam. This type of multiphoton singlet beam may be useful in quantum communication to avoid decoherence. We show that although the photons are part of the same beam, they are never in the same plane-wave mode, which is characterized by spatial antibunching behavior in the plane normal to the propagation direction. 相似文献
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《Physics letters. [Part B]》1986,168(3):226-232
Cosmological constraints on a supersymmetric version of the standard model coupled to N = 1 supergravity are derived, in which gauge symmetry breaking is triggered by a Higgs singlet. Possible neutralino dark matter candidates are emphasized. In particular, the fermionic partner of the Higgs singlet is often the lightest supersymmetric particle, with a relic abundance near the critical closure density. 相似文献
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The vapor absorption of dibenzofuran has been reexamined, and the spectrum and lifetime of the vapor fluorescence have been measured. Also measured were the polarized absorption in durene host and the depolarized absorption, fluorescence, and phosphorescence in cyclododecane host at 4 K. The fluoresecent state is that corresponding to the 3000 Å absorption in all media, and no evidence was found for a weak transition at 3175 Å as reported by Pinkham and Wait. The mixed crystal spectra are heavily perturbed, but from the polarizations observed in durene the 3000 Å transition is assigned as (long axis polarized). 相似文献
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Luis A. Montero-Cabrera Yoana Pérez-Badell Mario Piris Ana L. Montero-Alejo José M. García de la Vega António J.C. Varandas 《Molecular physics》2013,111(24):3650-3657
A theoretical framework for modelling the electronic structure of absorbing molecules that may contribute to explain and even predict phenomena where a singlet exciton is converted to triplet is reported. The pathway is suggested to occur when the excited singlet and triplet electron density maps are similarly shaped at Frank Condon states. Calculations were carried for some linear acene excitons from their multielectronic wave functions and corresponding charge maps after a configuration interaction of singly excited determinants. For cases where the singlet fission effect has been reported, charge maps of certain higher energy singlet excitons show a relevant shape similarity with the corresponding lowest triplet. This method could enlighten the way for predicting transit between singlets and triplets of very big systems and also may help to explain experimental phenomena at femto and even attosecond scales. 相似文献
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T. K. Lim 《Nuclear Physics A》1972,180(2):668-672
The normalization factor for zero-range and finite-range DWBA calculations of (h, kd) reactions has been determined by three theoretical methods. Although the values obtained show a fair spread, they are all, nevertheless, close to the single N(h, kd) extracted from experiment. 相似文献
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Quasi-one-dimensional organic conductors are highly unconventional materials, which exhibit a wide variety of phenomena, including spin density waves, quantum Hall effect, and superconductivity. In this paper, we review some experimental and theoretical developments concerning the superconducting state of these systems, where a particular emphasis is placed on the possibility of triplet superconductivity. This possibility is supported by various experiments including upper critical field, Knight shift and NMR relaxation time measurements on the Bechgaard salt bistetramethyltetraselenafulvalene hexafluorophosphate [(TMTSF)2PF6]. However, similar NMR results are still lacking for another compound (TMTSF)2ClO4 and other members of the Bechgaard salts family. Furthermore, the pairing mechanism and order parameter symmetry are not yet fully known. Therefore, we include a discussion of both triplet and singlet pairing states, and analyse briefly the possibility that the symmetries of the superconducting order parameters are different for various compounds. Finally, we also discuss some open questions regarding the superconducting state of these systems. 相似文献
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1 excited-state absorption cross-section spectrum of DODCI in ethylene glycol is determined in the wavelength range from 500 nm
to 750 nm. The S1 state is populated by amplified femtosecond dye laser pulses (wavelength 592 nm) and the S1-state absorption and emission behaviour is probed with a femtosecond light continuum. A general analysis procedure is developed
to extract absolute excited-state absorption cross-sections from the measured transmissions. For DODCI in ethylene glycol
the wavelength regions of saturable absorption (mode-locking application), reverse saturable absorption (optical limiter application),
and effective stimulated emission (laser application) are determined.
Received: 25 July 1996 相似文献