221 research outputs found

    Supersymmetric Gauge Theories with an Affine Quantum Moduli Space

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    All supersymmetric gauge theories based on simple groups which have an affine quantum moduli space, i.e. one generated by gauge invariants with no relations, W=0, and anomaly matching at the origin, are classified. It is shown that the only theories with no gauge invariants (and moduli space equal to a single point) are the two known examples, SU(5) with 5-bar + 10 and SO(10) with a spinor. The index of the matter representation must be at least as big as the index of the adjoint in theories which have a non-trivial relation among the gauge invariants.Comment: Incorrect proof that theories with constraints must have mu >= mu(adj) replaced by a correct one (6 pages, uses revtex, amssymb, array

    Topology of "white" stars in relativistic fragmentation of light nuclei

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    In the present paper, experimental observations of the multifragmentation processes of light relativistic nuclei carried out by means of emulsions are reviewed. Events of the type of "white" stars in which the dissociation of relativistic nuclei is not accompanied by the production of mesons and the target-nucleus fragments are considered. A distinctive feature of the charge topology in the dissociation of the Ne, Mg, Si, and S nuclei is an almost total suppression of the binary splitting of nuclei to fragments with charges higher than 2. The growth of the nuclear fragmentation degree is revealed in an increase in the multiplicity of singly and doubly charged fragments with decreasing charge of the non-excited part of the fragmenting nucleus. The processes of dissociation of stable Li, Be, B, C, N, and O isotopes to charged fragments were used to study special features of the formation of systems consisting of the lightest α\alpha, d, and t nuclei. Clustering in form of the 3^3He nucleus can be detected in "white" stars via the dissociation of neutron-deficient Be, B, C, and N isotopes.Comment: 20 pages, 3 figures, 9 tables, conference: Conference on Physics of Fundamental Interactions, Moscow, Russia, 1-5 Mar 2004.(Author's translation

    Plane torsion waves in quadratic gravitational theories

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    The definition of the Riemann-Cartan space of the plane wave type is given. The condition under which the torsion plane waves exist is found. It is expressed in the form of the restriction imposed on the coupling constants of the 10-parametric quadratic gravitational Lagrangian. In the mathematical appendix the formula for commutator of the variation operator and Hodge operator is proved. This formula is applied for the variational procedure when the gravitational field equations are obtained in terms of the exterior differential forms.Comment: 3 May 1998. - 11

    Electromagnetic dissociation of relativistic 8^8B nuclei in nuclear track emulsion

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    Experimental data on fragmentation channels in peripheral interactions of 8^8B nuclei in nuclear track emulsions are presented. A detailed analysis made it possible to justify selections of events of the electromagnetic-dissociation process 8^8B →7\to^7Be + \emph{p} and to estimate its cross section. Events of 10^{10}C peripheral dissociation that were observed in the same exposure are described.Comment: 12 pages, 10 figures, 4 tables, Published in Phys.Atom.Nucl.72:690-701,200

    Exposure of Nuclear Track Emulsion to a Mixed Beam of Relativistic 12^{12}N, 10^{10}C, and 7^7Be Nuclei

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    A nuclear track emulsion was exposed to a mixed beam of relativistic 12^{12}N, 10^{10}C, and 7^7Be nuclei having a momentum of 2 GeV/cc per nucleon. The beam was formed upon charge exchange processes involving 12^{12}C primary nuclei and their fragmentation. An analysis indicates that 10^{10}C nuclei are dominant in the beam and that 12^{12}N nuclei are present in it. The charge topology of relativistic fragments in the coherent dissociation of these nuclei is presented.Comment: ISSN 1063-7788, Pleiades Publishing, Ltd., 201

    Search for the exotic Ξ−−(1860)\Xi^{--}(1860) Resonance in 340GeV/c Σ−\Sigma^--Nucleus Interactions

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    We report on a high statistics search for the Ξ−−(1860)\Xi^{--}(1860) resonance in Σ−\Sigma^--nucleus collisions at 340GeV/c. No evidence for this resonance is found in our data sample which contains 676000 Ξ−\Xi^- candidates above background. For the decay channel Ξ−−(1860)→Ξ−π−\Xi^{--}(1860) \to \Xi^-\pi^- and the kinematic range 0.15<xF<<x_F<0.9 we find a 3σ\sigma upper limit for the production cross section of 3.1 and 3.5 ÎŒ\mub per nucleon for reactions with carbon and copper, respectively.Comment: 5 pages, 4 figures, modification of ref. 43 and 4

    Differential Transverse Flow in Central C-Ne and C-Cu Collisions at 3.7 GeV/nucleon

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    Differential transverse flow of protons and pions in central C-Ne and C-Cu collisions at a beam energy of 3.7 GeV/nucleon was measured as a function of transverse momentum at the SKM-200-GIBS setup of JINR. In agreement with predictions of a transversely moving thermal model, the strength of proton differential transverse flow is found to first increase gradually and then saturate with the increasing transverse momentum in both systems. While pions are preferentially emitted in the same direction of the proton transverse flow in the reaction of C-Ne, they exhibit an anti-flow to the opposote direction of the proton transverse flow in the reaction of C-Cu due to stronger shadowing effects of the heavier target in thr whole range of transverse momentum.Comment: 15 pages, 5 figure

    QCD in the nuclear medium and effects due to Cherenkov gluons

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    The equations of in-medium gluodynamics are proposed. Their classical lowest order solution is explicitly shown for a color charge moving with constant speed. For nuclear permittivity larger than 1 it describes emission of Cherenkov gluons resembling results of classical electrodynamics. The values of the real and imaginary parts of the nuclear permittivity are obtained from the fits to experimental data on the double-humped structure around the away-side jet obtained at RHIC. The dispersion of the nuclear permittivity is predicted by comparing the RHIC, SPS and cosmic ray data. This is important for LHC experiments. Cherenkov gluons may be responsible for the asymmetry of dilepton mass spectra near rho-meson, observed in the SPS experiment with excess in the low-mass wing of the resonance. This feature is predicted to be common for all resonances. The "color rainbow" quantum effect might appear according to higher order terms of in-medium QCD if the nuclear permittivity depends on color.Comment: 29 p., 4 figs; for "Phys. Atom. Nucl." volume dedicated to 80th birthday of L.B. Okun; minor corrections on pp. 11 and 13 in v

    Atmospheric Muon Flux at Sea Level, Underground, and Underwater

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    The vertical sea-level muon spectrum at energies above 1 GeV and the underground/underwater muon intensities at depths up to 18 km w.e. are calculated. The results are particularly collated with a great body of the ground-level, underground, and underwater muon data. In the hadron-cascade calculations, the growth with energy of inelastic cross sections and pion, kaon, and nucleon generation in pion-nucleus collisions are taken into account. For evaluating the prompt muon contribution to the muon flux, we apply two phenomenological approaches to the charm production problem: the recombination quark-parton model and the quark-gluon string model. To solve the muon transport equation at large depths of homogeneous medium, a semi-analytical method is used. The simple fitting formulas describing our numerical results are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially all underground data on the muon intensity correlate with each other and with predicted depth-intensity relation for conventional muons to within 10%. However, the high-energy sea-level data as well as the data at large depths are contradictory and cannot be quantitatively decribed by a single nuclear-cascade model.Comment: 47 pages, REVTeX, 15 EPS figures included; recent experimental data and references added, typos correcte

    Heavy Baryon Specroscopy from the Lattice

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    The results of an exploratory lattice study of heavy baryon spectroscopy are presented. We have computed the full spectrum of the eight baryons containing a single heavy quark, on a 243×4824^3\times 48 lattice at ÎČ=6.2\beta=6.2, using an O(a)O(a)-improved fermion action. We discuss the lattice baryon operators and give a method for isolating the contributions of the spin doublets (ÎŁ,Σ∗)(\Sigma,\Sigma^*), (Ξâ€Č,Ξ∗)(\Xi',\Xi^*) and (Ω,Ω∗)(\Omega,\Omega^*) to the correlation function of the relevant operator. We compare our results with the available experimental data and find good agreement in both the charm and the beauty sectors, despite the long extrapolation in the heavy quark mass needed in the latter case. We also predict the masses of several undiscovered baryons. We compute the \Lambda-\mbox{pseudoscalar meson} and Σ−Λ\Sigma-\Lambda mass splittings. Our results, which have errors in the range 10−30% 10-30\%, are in good agreement with the experimental numbers. For the Σ∗−Σ\Sigma^*-\Sigma mass splitting, we find results considerably smaller than the experimental values for both the charm and the beauty baryons, although in the latter case the experimental results are still preliminary. This is also the case for the lattice results for the hyperfine splitting for the heavy mesons.Comment: 31 pages LaTex, with postscript figures include
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