25,243 research outputs found

    The potential (iz)^m generates real eigenvalues only, under symmetric rapid decay conditions

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    We consider the eigenvalue problems -u"(z) +/- (iz)^m u(z) = lambda u(z), m >= 3, under every rapid decay boundary condition that is symmetric with respect to the imaginary axis in the complex z-plane. We prove that the eigenvalues lambda are all positive real.Comment: 23 pages and 1 figur

    Dynamical evolution of the mass function and radial profile of the Galactic globular cluster system

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    Evolution of the mass function (MF) and radial distribution (RD) of the Galactic globular cluster (GC) system is calculated using an advanced and a realistic Fokker-Planck (FP) model that considers dynamical friction, disc/bulge shocks and eccentric cluster orbits. We perform hundreds of FP calculations with different initial cluster conditions, and then search a wide-parameter space for the best-fitting initial GC MF and RD that evolves into the observed present-day Galactic GC MF and RD. By allowing both MF and RD of the initial GC system to vary, which is attempted for the first time in the present Letter, we find that our best-fitting models have a higher peak mass for a lognormal initial MF and a higher cut-off mass for a power-law initial MF than previous estimates, but our initial total masses in GCs, M_{T,i} = 1.5-1.8x10^8 Msun, are comparable to previous results. Significant findings include that our best-fitting lognormal MF shifts downward by 0.35 dex during the period of 13 Gyr, and that our power-law initial MF models well-fit the observed MF and RD only when the initial MF is truncated at >~10^5 Msun. We also find that our results are insensitive to the initial distribution of orbit eccentricity and inclination, but are rather sensitive to the initial concentration of the clusters and to how the initial tidal radius is defined. If the clusters are assumed to be formed at the apocentre while filling the tidal radius there, M_{T,i} can be as high as 6.9x10^8 Msun, which amounts to ~75 per cent of the current mass in the stellar halo.Comment: To appear in May 2008 issue of MNRAS, 386, L6

    The D0 same-charge dimuon asymmetry and possibile new CP violation sources in the BsBˉsB_s-\bar{B}_s system

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    Recently, the D0 collaboration reported a large CP violation in the same-sign dimuon charge asymmetry which has the 3.2σ3.2 \sigma deviation from the value estimated in the Standard Model. In this paper, several new physics models are considered: the MSSM, two Higgs doublet model, the recent dodeca model, and a new ZZ' model. Generally, it is hard to achieve such a large CP violation consistently with other experimental constraints. We find that a scheme with extra non-anomalous U(1)' gauge symmetry is barely consistent. In general, the extra ZZ' gauge boson induces the flavor changing neutral current interactions at tree level, which is the basic reason allowing a large new physics CP violation. To preserve the U(1)' symmetry at high energy, SU(2)L_L singlet exotic heavy quarks of mass above 1 TeV and the Standard Model gauge singlet scalars are introduced.Comment: 12 pages, 13 figure

    Hawking Radiation of Black p-Branes from Gravitational Anomaly

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    We investigate the Hawking radiation of black pp-branes of superstring theories using the method of anomaly cancelation, specially, we use the method of [S. Iso, H. Umetsu and F. Wilczek, {\sl Phys. Rev. Lett.} {\bf 96}, 151302 (2006); {\sl Phys. Rev. D} {\bf 74}, 044017 (2006)]. The metrics of black pp-branes are spherically symmetric, but not the Schwarzschild type. In order to simplify the calculation, we first make a coordinate transformation to transform the metric to the Schwarzschild type. Then we calculate its energy-momentum flux from the method of anomaly cancelation of the above mentioned references. The obtained energy-momentum flux is equal to a black body radiation, the thermodynamic temperature of the radiation is equal to its Hawking temperature. And we find that the results are not changed for the original non-Schwarzschild type spherically symmetric metric.Comment: 19 pages Latex, some mistakes correcte

    Thermalization of quark-gluon matter by 2-to-2 and 3-to-3 elastic scatterings

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    Thermalization of quark-gluon matter is studied with a transport equation that includes contributions of 2-to-2 and 3-to-3 elastic scatterings. Thermalization time is related to the squared amplitudes for the elastic scatterings that are calculated in perturbative QCD.Comment: LaTex, 6 pages, 3 figures, talk presented at the 19th international conference on ultra-relativistic nucleus-nucleus collisions, Shanghai, China, Nov. 200

    Eigenvalues of PT-symmetric oscillators with polynomial potentials

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    We study the eigenvalue problem u(z)[(iz)m+Pm1(iz)]u(z)=λu(z)-u^{\prime\prime}(z)-[(iz)^m+P_{m-1}(iz)]u(z)=\lambda u(z) with the boundary conditions that u(z)u(z) decays to zero as zz tends to infinity along the rays argz=π2±2πm+2\arg z=-\frac{\pi}{2}\pm \frac{2\pi}{m+2}, where Pm1(z)=a1zm1+a2zm2+...+am1zP_{m-1}(z)=a_1 z^{m-1}+a_2 z^{m-2}+...+a_{m-1} z is a polynomial and integers m3m\geq 3. We provide an asymptotic expansion of the eigenvalues λn\lambda_n as n+n\to+\infty, and prove that for each {\it real} polynomial Pm1P_{m-1}, the eigenvalues are all real and positive, with only finitely many exceptions.Comment: 23 pages, 1 figure. v2: equation (14) as well as a few subsequent equations has been changed. v3: typos correcte

    Person prominence and relation prominence : on the typology of syntactic relations with particular reference to Yucatec Maya

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    PM3969, ISO 639-3 : -, Maya language--Syntax1. Introduction 2. Theoretical background 2.1. The cognitive structure of a situation 2.1.1. Situation, situation core, and participants 2.1.2. Participant features 2.1.3. Participant roles 2.2. Syntactic functions 2.3. Correlation between syntactic functions and participant roles 3. Prominence in typology 3.1. Subject prominence vs. topic prominence 3.2. Reference domination vs. role domination 3.3. Person prominence vs. relation prominence 4. Languages investigated 4.1. Yucatec Maya 4.2. Samoan 4.3. Maori 4.4. Tamil 4.5. Lezgian 4.6. Korean 5. Prominence in syntactic constructions 5.1. Introduction 5.2. Higher predicates 5.2.1. Modal predicates 5.2.2. Phase predicates 5.2.3. Tense, aspect, and aktionsart auxiliaries 5.3. Possessive constructions 5.3.1. Part-whole relations 5.3.2. Ascription of possession 5.3.3. Predication of belonging 5.3.4. Ascription of property to body part 5.3.5. Affection of possessor 5.4. Mental, sensual, and emotional states and processes 5.4.1. Preliminaries 5.4.2. Sensual states and processes 5.4.3. Emotional states and processes 5.4.4. Mental states and processes 5.4.5. Conclusion 5.5. Benefactive 6. Relation prominence in YM: a historical-comparative perspective 6.1. Colonial Yucatec Maya 6.1.1. Preliminaries 6.1.2. Modal predicates 6.1.3. Phase predicates 6.1.4. Aspect auxiliaries 6.1.5. Conclusion 6.2. Cognate languages 6.2.1. Preliminaries 6.2.2. Higher predicates 6.2.3. Possessive constructions 6.2.4. Mental, sensual and emotional states and processes 6.2.5. Benefactive 6.2.6. Conclusion 7. Typology 7.1. Empirical generalizations 7.1.1. The domain of possession 136 7.1.2. Higher predicates 7.1.3. Participant roles 7.2. Grammatical correlations 7.3. Conclusion Indices Abbreviations Morpheme glosses & syntactic categories Languages Sources of data Bibliographical references LIST OF FIGURES LIST OF TABLE

    On the shape of spectra for non-self-adjoint periodic Schr\"odinger operators

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    The spectra of the Schr\"odinger operators with periodic potentials are studied. When the potential is real and periodic, the spectrum consists of at most countably many line segments (energy bands) on the real line, while when the potential is complex and periodic, the spectrum consists of at most countably many analytic arcs in the complex plane. In some recent papers, such operators with complex PT\mathcal{PT}-symmetric periodic potentials are studied. In particular, the authors argued that some energy bands would appear and disappear under perturbations. Here, we show that appearance and disappearance of such energy bands imply existence of nonreal spectra. This is a consequence of a more general result, describing the local shape of the spectrum.Comment: 5 pages, 2 figure

    Distribution of magnetic domain pinning fields in GaMnAs ferromagnetic films

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    Using the angular dependence of the planar Hall effect in GaMnAs ferromagnetic films, we were able to determine the distribution of magnetic domain pinning fields in this material. Interestingly, there is a major difference between the pinning field distribution in as-grown and in annealed films, the former showing a strikingly narrower distribution than the latter. This conspicuous difference can be attributed to the degree of non-uniformity of magnetic anisotropy in both types of films. This finding provides a better understanding of the magnetic domain landscape in GaMnAs that has been the subject of intense debate
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