191 research outputs found
The lunar radio flux during Leonid meteor showers and lunar eclipse
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
within and beyond the Standard Model
We revisit (with and ) 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
. Numerically, the branching ratios of
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 in Type-II 2HDM
with large , and 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
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 ,
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
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 T\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)
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
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 -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
We study flavor changing processes and 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
and . We find that
these branching ratios could be as large as and 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
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
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 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 and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- 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
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at 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
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