9,178 research outputs found
Addendum to: Search for anomalous top-gluon couplings at LHC revisited
In our latest paper "Search for anomalous top-gluon couplings at LHC
revisited" in Eur. Phys. J. C65 (2010), 127-135 (arXiv:0910.3049 [hep-ph]), we
studied possible effects of nonstandard top-gluon couplings through the
chromoelectric and chromomagnetic moments of the top quark using the total
cross section of ppbar/pp --> ttbar X at Tevatron/LHC. There we pointed out
that LHC data could give a stronger constraint on those two parameters, which
would be hard to obtain from Tevatron data alone. We show here the first CMS
measurement of this cross section actually makes it possible.Comment: 5 pages, 1 figure, LaTeX2e, Final version (to appear in Eur. Phys. C
The Inverse Scattering Method, Lie-Backlund Transformations and Solitons for Low-energy Effective Field Equations of 5D String Theory
In the framework of the 5D low-energy effective field theory of the heterotic
string with no vector fields excited, we combine two non-linear methods in
order to construct a solitonic field configuration. We first apply the inverse
scattering method on a trivial vacuum solution and obtain an stationary
axisymmetric two-soliton configuration consisting of a massless gravitational
field coupled to a non-trivial chargeless dilaton and to an axion field endowed
with charge. The implementation of this method was done following a scheme
previously proposed by Yurova. We also show that within this scheme, is not
possible to get massive gravitational solitons at all. We then apply a
non-linear Lie-Backlund matrix transformation of Ehlers type on this massless
solution and get a massive rotating axisymmetric gravitational soliton coupled
to axion and dilaton fields endowed with charges. We study as well some
physical properties of the constructed massless and massive solitons and
discuss on the effect of the generalized solution generating technique on the
seed solution and its further generalizations.Comment: 17 pages in latex, changed title, improved text, added reference
Dilepton azimuthal correlations in tt production
The dilepton azimuthal correlation, namely the difference phi between the azimuthal
angles of the positive and negative charged lepton in the laboratory frame, provides
a stringent test of the spin correlation in tt production at the Large Hadron Collider. We
introduce a parameterisation of the differential cross section dalpha=dphi in terms of a Fourier
series and show that the third-order expansion provides a su ciently accurate approximation.
This expansion can be considered as a `bridge' between theory and data, making it
very simple to cast predictions in the Standard Model (SM) and beyond, and to report
measurements, without the need to provide the numbers for the whole binned distribution.
We show its application by giving predictions for the coeffcients in the presence of
(i) an anomalous top chromomagnetic dipole moment; (ii) an anomalous tbW interaction.
The methods presented greatly facilitate the study of this angular distribution, which is of
special interest given the 3:2(3:7) deviation from the SM next-to-leading order prediction
found by the ATLAS collaboration in Run 2 data.This work has been supported by MINECO Project FPA 2013-47836-C3-2-P (including
ERDF)
K*(892)0 Production in Relativistic Heavy Ion Collisions at sqrt(s_NN) = 130 GeV
Preliminary results on the K*(892)0 -> pi + K production using the
mixed-event technique are presented. The measurements are performed at
mid-rapidity by the STAR detector in sqrt(s_NN) = 130 GeV Au-Au collisions at
RHIC. The K*0 to negative hadron, kaon and phi ratios are obtained and compared
to the measurements in e+e-, pp and pbarp at various energies.Comment: 8 pages, 3 figures, proceedings of Strange Quarks in Matter
(SQM2001), Frankfurt am Main, Germany, to be published in J. Phys.
Phenomenology of Quantum Gravity and its Possible Role in Neutrino Anomalies
New phenomenological models of Quantum Gravity have suggested that a
Lorentz-Invariant discrete spacetime structure may become manifest through a
nonstandard coupling of matter fields and spacetime curvature. On the other
hand, there is strong experimental evidence suggesting that neutrino
oscillations cannot be described by simply considering neutrinos as massive
particles. In this manuscript we motivate and construct one particular
phenomenological model of Quantum Gravity that could account for the so-called
neutrino anomalies.Comment: For the proceedings of "Relativity and Gravitation: 100 Years after
Einstein in Prague" (June 2012, Prague
Determination of the Hurst Exponent by Use of Wavelet Transforms
We propose a new method for (global) Hurst exponent determination based on
wavelets. Using this method, we analyze synthetic data with predefined Hurst
exponents, fracture surfaces and data from economy. The results are compared
with those obtained from Fourier spectral analysis. When many samples are
available, the wavelet and Fourier methods are comparable in accuracy. However,
when one or only a few samples are available, the wavelet method outperforms
the Fourier method by a large margin.Comment: 10 pages RevTeX, 13 Postscript figures. Some additional material
compared to previous versio
A Letter of Intent to Build a MiniBooNE Near Detector: BooNE
There is accumulating evidence for a difference between neutrino and
antineutrino oscillations at the eV scale. The MiniBooNE
experiment observes an unexplained excess of electron-like events at low
energies in neutrino mode, which may be due, for example, to either a neutral
current radiative interaction, sterile neutrino decay, or to neutrino
oscillations involving sterile neutrinos and which may be related to the LSND
signal. No excess of electron-like events (), however, is
observed so far at low energies in antineutrino mode. Furthermore, global 3+1
and 3+2 sterile neutrino fits to the world neutrino and antineutrino data
suggest a difference between neutrinos and antineutrinos with significant
() disappearance. In order to
test whether the low-energy excess is due to neutrino oscillations and whether
there is a difference between and disappearance, we
propose building a second MiniBooNE detector at (or moving the existing
MiniBooNE detector to) a distance of m from the Booster Neutrino
Beam (BNB) production target. With identical detectors at different distances,
most of the systematic errors will cancel when taking a ratio of events in the
two detectors, as the neutrino flux varies as to a calculable
approximation. This will allow sensitive tests of oscillations for both
and appearance and and disappearance.
Furthermore, a comparison between oscillations in neutrino mode and
antineutrino mode will allow a sensitive search for CP and CPT violation in the
lepton sector at short baseline ( eV).Comment: 43 pages, 40 figure
A Possible Detection of Occultation by a Proto-planetary Clump in GM Cephei
GM Cep in the young (~4 Myr) open cluster Trumpler 37 has been known to be an
abrupt variable and to have a circumstellar disk with very active accretion.
Our monitoring observations in 2009-2011 revealed the star to show sporadic
flare events, each with brightening of < 0.5 mag lasting for days. These
brightening events, associated with a color change toward the blue, should
originate from an increased accretion activity. Moreover, the star also
underwent a brightness drop of ~1 mag lasting for about a month, during which
the star became bluer when fainter. Such brightness drops seem to have a
recurrence time scale of a year, as evidenced in our data and the photometric
behavior of GM Cep over a century. Between consecutive drops, the star
brightened gradually by about 1 mag and became blue at peak luminosity. We
propose that the drop is caused by obscuration of the central star by an
orbiting dust concentration. The UX Orionis type of activity in GM Cep
therefore exemplifies the disk inhomogeneity process in transition between
grain coagulation and planetesimal formation in a young circumstellar disk.Comment: In submission to the Astrophysical Journal, 4 figure
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