192 research outputs found

    The lunar radio flux during Leonid meteor showers and lunar eclipse

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    Significance variations of lunar radio flux at the wavelength of 2.46 cm were detected in Irbene (Latvia) during the maxima of Leonid shower on the Moon in 2000 and 2001. These results were interpreted as detection of lunar radio emission of seismic origin. However, radio observations of the Moon at the wavelength of 6 cm in Ukraine did not show any signal enhancement of lunar radio flux on November 17–19, 2001. Except meteoroid impacts, the eclipses can lead to increasing of intensity of non-thermal radio emission due to formation of micro cracks in lunar regolith when the regolith temperature during eclipses is quickly changes. The results of simultaneous observations of the full lunar eclipse at the wavelengths of 18 cm and 1.35 cm in Simeiz (Ukraine) and Pushchino (Russia) on November 8–9, 2003 are presented. According to these observations the correlation between fluctuations of lunar radio flux at both wavelengths is absent. Thus, the previously detected fluctuations of lunar flux at the wavelength of 2.6 cm may have the instrumental origin. Lunar origin of detected fluctuations could be confirmed by simultaneous observations at two radio telescopes. Our future goal is try to detect the lunar radio emission of seismic origin at the lower frequencies, because the intensity of such emission during the earthquakes increases with a decreasing frequency

    χQJ+\chi_{QJ} \to\ell^+\ell^- within and beyond the Standard Model

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    We revisit χQJ+\chi_{QJ}\to \ell^+\ell^- (with J=0,1,2J=0,1,2 and Q=b,cQ=b,c) within the Standard Model (SM). The electro-magnetic contributions are given in color-singlet model with non-vanishing lepton masses at the leading order of vv. Numerically, the branching ratios of χQJ+\chi_{QJ}\to\ell^{+}\ell^{-} predicted within the SM are so small that such decays are barely possible to be detected at future BESIII and SuperB experiments, but may be possible to be observed at the LHC. We investigate χb0+\chi_{b0}\to\ell^+\ell^- in Type-II 2HDM with large tanβ\tan\beta, and χb2+\chi_{b2}\to\ell^+\ell^- in the Randall-Sundrum model, to see their chance to be observed in future experiments.Comment: 11 pages, 8 figures. To match the published versio

    Collinear effective theory at subleading order and its application to heavy-light currents

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    We consider a collinear effective theory of highly energetic quarks with energy E, interacting with collinear and soft gluons by integrating out collinear degrees of freedom to subleading order. The collinear effective theory offers a systematic expansion in power series of a small parameter lambda ~ p_{\perp}/E, where p_{\perp} is the transverse momentum of a collinear particle. We construct the effective Lagrangian to first order in λ\lambda, and discuss its features including additional symmetries such as collinear gauge invariance and reparameterization invariance. Heavy-light currents can be matched from the full theory onto the operators in the collinear effective theory at one loop and to order lambda. We obtain heavy-light current operators in the effective theory, calculate their Wilson coefficients at this order, and the renormalization group equations for the Wilson coefficients are solved. As an application, we calculate the form factors for decays of B mesons to light energetic mesons to order lambda and at leading-logarithmic order in alpha_s.Comment: 29 pages, 5 figures, revised versio

    Sensitive Observations of Radio Recombination Lines in Orion and W51: The Data and Detection of Systematic Recombination Line Blueshifts Proportional to Impact Broadening

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    Sensitive spectral observations made in two frequency bands near 6.0 and 17.6 GHz are described for Orion and W51. Using frequency switching we were able to achieve a dynamic range in excess of 10,000 without fitting sinusoidal or polynomial baselines. This enabled us to detect lines as weak as TA 1mKinthesestrongcontinuumsources.Hydrogenrecombinationlineswith_{A} ~1mK in these strong continuum sources. Hydrogen recombination lines with \Delta n$ as high as 25 have been detected in Orion. In the Orion data, where the lines are stronger, we have also detected a systematic shift in the line center frequencies proportional to linewidth that cannot be explained by normal optical depth effects.Comment: 22 pages, 13 figures. Accepted for publication in Astrophysics and Space Scienc

    Expansion of bound state energies in powers of m/M and (1-m/M)

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    Elaborating on a previous letter, we use a new approach to compute energy levels of a non-relativistic bound-state of two constituents, with masses m and M, by systematic expansions - one in powers of m/M and another in powers of (1-m/M). Technical aspects of the calculations are described in detail. Theoretical predictions are given for O(alpha(Z*alpha)^5) radiative recoil and O((Z*alpha)^6) pure recoil corrections to the average energy shift and hyperfine splitting relevant for hydrogen, muonic hydrogen, and muonium.Comment: 9 pages, revte

    Heavy quarkonium: progress, puzzles, and opportunities

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    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    Flavor Changing processes in Quarkonium Decays

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    We study flavor changing processes ΥB/BˉXs\Upsilon \to B/{\bar B} X_s and J/ψD/DˉXuJ/\psi \to D/{\bar D} X_u in the B factories and the Tau-Charm factories. In the standard model, these processes are predicted to be unobservable, so they serve as a probe of the new physics. We first perform a model independent analysis, then examine the predictions of models; such as TopColor models, MSSM with R-parity violation and the two Higgs doublet model; for the branching ratios of ΥB/BˉXs\Upsilon \to B/{\bar B} X_s and J/ψD/DˉXuJ/\psi \to D/{\bar D} X_u . We find that these branching ratios could be as large as 10610^{-6} and 10510^{-5} in the presence of new physics.Comment: Minor changes in the last section. Latex 22 pages, one figure. To appear in Phys. Rev.

    Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS

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    The longitudinal polarisation transfer from muons to lambda and anti-lambda hyperons, D_LL, has been studied in deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to lambda and anti-lambda produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of D^lambda_LL are compatible with zero, while D^anti-lambda_LL tends to increase with xF, reaching values of 0.4 - 0.5. The resulting average values are D^lambda_LL = -0.012 +- 0.047 +- 0.024 and D^anti-lambda_LL = 0.249 +- 0.056 +- 0.049. These results are discussed in the frame of recent model calculations.Comment: 13 pages, 7 figure

    Two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76 TeV

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    The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/388

    Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}} = 2.76 TeV

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    Inclusive transverse momentum spectra of primary charged particles in Pb-Pb collisions at sNN\sqrt{s_{_{\rm NN}}} = 2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross section. The measured charged particle spectra in η<0.8|\eta|<0.8 and 0.3<pT<200.3 < p_T < 20 GeV/cc are compared to the expectation in pp collisions at the same sNN\sqrt{s_{\rm NN}}, scaled by the number of underlying nucleon-nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAAR_{\rm AA}. The result indicates only weak medium effects (RAAR_{\rm AA} \approx 0.7) in peripheral collisions. In central collisions, RAAR_{\rm AA} reaches a minimum of about 0.14 at pT=6p_{\rm T}=6-7GeV/cc and increases significantly at larger pTp_{\rm T}. The measured suppression of high-pTp_{\rm T} particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb-Pb collisions at the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
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