508 research outputs found

    Solar Neutrinos as Background in Direct Dark Matter Searches

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    The coherent contribution of all neutrons in neutrino nucleus scattering due to the neutral current is examined considering the boron solar neutrinos. These neutrinos could potentially become a source of background in the future dark matter searches aiming at nucleon cross sections in the region well below the few events per ton per year.Comment: 6 pages, 5 figures, Submitted for the DSU proceedings to be published by the American institute of Physics (AIP). References adde

    Some aspects of Θ+\Theta^+ parity determination in the reaction γNΘ+KˉNKKˉ\gamma N\to \Theta^+ \bar{K}\to N K \bar{K}

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    We analyze the problem of how to determine the parity of the Θ+\Theta^+ pentaquark in the reaction γNKΘNKKˉ\gamma N\to K\Theta\to NK\bar{K}, where N=n,pN=n,p. Our model calculations indicate that the contribution of the non-resonant background of the reaction γNNKKˉ\gamma N\to NK\bar{K} cannot be neglected, and that suggestions to determine the parity based solely on the initial-stage process γNKΘ\gamma N\to K\Theta cannot be implemented cleanly. We discuss the various mechanisms that contribute to the background, and we identify some spin observables which are sensitive.Comment: 39 pages, 25 figure

    Scaling Laws and Effective Dimension in Lattice SU(2) Yang-Mills Theory with a Compactified Extra Dimension

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    Monte Carlo simulations are performed in a five-dimensional lattice SU(2) Yang-Mills theory with a compactified extra dimension, and scaling laws are studied. Our simulations indicate that as the compactification radius RR decreases, the confining phase spreads more and more to the weak coupling regime, and the effective dimension of the theory changes gradually from five to four. Our simulations also indicate that the limit a4to0a_4 to 0 with R/a4R/a_4 kept fixed exists both in the confining and deconfining phases if R/a4R/a_4 is small enough, where a4a_4 is the lattice spacing in the four-dimensional direction. We argue that the color degrees of freedom in QCD are confined only for R<RmaxR < R_{\rm max}, where a rough estimate shows that 1/Rmax1/R_{\rm max} lies in the TeV range. Comments on deconstructing extra dimensions are given.Comment: 15 pages, TeX, 5 figure

    Critical point of QCD at finite T and \mu, lattice results for physical quark masses

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    A critical point (E) is expected in QCD on the temperature (T) versus baryonic chemical potential (\mu) plane. Using a recently proposed lattice method for \mu \neq 0 we study dynamical QCD with n_f=2+1 staggered quarks of physical masses on L_t=4 lattices. Our result for the critical point is T_E=162 \pm 2 MeV and \mu_E= 360 \pm 40 MeV. For the critical temperature at \mu=0 we obtained T_c=164 \pm 2 MeV. This work extends our previous study [Z. Fodor and S.D.Katz, JHEP 0203 (2002) 014] by two means. It decreases the light quark masses (m_{u,d}) by a factor of three down to their physical values. Furthermore, in order to approach the thermodynamical limit we increase our largest volume by a factor of three. As expected, decreasing m_{u,d} decreased \mu_E. Note, that the continuum extrapolation is still missingComment: 10 pages, 2 figure

    Evolution of the ring current energy during May 2-4, 1998 magnetic storm

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    We study the evolution of the ring current energy density during May 2-4, 1998 storm event as measured by Polar CAMMICE/MICS instrument and modelled by proton tracing in the guiding center approximation. Particle data from Polar shows that during the storm main phase protons with medium energies (20-80 keV) contribute more to the total ring current energy than the high energy protons (80-200 keV) whereas during the recovery phase high energies dominate. We trace protons with arbitrary pitch angles numerically in the guiding center approximation taking into account charge-exchange losses. Tracing is performed in the large-scale and smaller-scale time-dependent magnetic and electric field models. We model the substorm activity by several electric field pulses at times of the substorm onsets. It is shown that impulsive electric fields associated with substorms are effective in the proton transport and energization to higher energies more than 100 keV in the storm time ring current

    Possible background reductions in double beta decay experiments

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    The background induced by radioactive impurities of 208Tl^{208}\rm Tl and 214Bi^{214}\rm Bi in the source of the double beta experiment NEMO-3 has been investigated. New methods of data analysis which decrease the background from the above mentioned contamination are identified. The techniques can also be applied to other double beta decay experiments capable of measuring independently the energies of the two electrons.Comment: 15 pages, 13 figures, accepted in the Nuclear Instruments and Methods

    Systematic analysis of pT -distributions in p + p collisions

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    A systematic analysis of transverse momentum distribution of hadrons produced in ultra-relativistic p + p collisions is presented. We investigate the effective temperature and the entropic parameter from the non-extensive thermodynamic theory of strong interaction. We conclude that the existence of a limiting effective temperature and of a limiting entropic parameter is in accordance with experimental data.Comment: 9 pages, 5 figure

    Ground-gamma band mixing and evolution of collectivity in even-even neutron-rich nuclei with 40<Z<50

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    We propose an extended band mixing formalism capable of describing the ground-gamma band interaction in a wide range of collective spectra beyond the regions of well deformed nuclei. On this basis we explain the staggering effects observed in the gamma bands of Mo, Ru and Pd nuclei providing a consistent interpretation of new experimental data in the neutron rich region. As a result the systematic behavior of the odd-even staggering effect and some general characteristics of the spectrum such as the mutual disposition of the bands, the interaction strength and the band structures is explained as the manifestation of respective changes in collective dynamics of the system.Comment: 17 pages, 6 figures, 4 table

    Ultraviolet Fixed Points in Gauge and SUSY Field Theories in Extra Dimensions

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    We consider gauge field theories in D>4D>4 following the Wilson RG approach and show that they possess the ultraviolet fixed points where the gauge coupling is dimensionless in any space-time dimension. At the fixed point the anomalous dimensions of the field and vertex operators are known exactly. These fixed points are nonperturbative and correspond to conformal invariant theories. The same phenomenon also happens in supersymmetric theories with the Yukawa type interactions.Comment: LaTeX, 10pp. v2: Comments and references adde
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