69 research outputs found
Overview of theoretical precision of the luminosity at future electron-positron colliders
For both the FCC-ee and the ILC, to exploit properly the respective precision physics program, the theoretical precision tag on the respective luminosity will need to be improved from the analogs of the 0.054%(0.061%) results at LEP at , where the former (latter) LEP result has (does not have) the pairs correction. At the FCC-ee at one needs improvement to 0.01%, for example. We present an overview of the roads one may take to reach the required 0.01% precision tag at the FCC-ee and of what the corresponding precision expectations would be for the FCC-ee, ILC, ILC and CLIC setups
Ramond-Ramond (boundary) states
The description of D-branes as boundary states for type II string theories
(in the covariant formulation) requires particular care in the R-R sector. Also
the vertices for R-R potentials that can couple to D-branes need a careful
handling. As an illustration of this, the example of the D0-D8 system is
reviewed, where a ``microscopic'' description of the interaction via exchange
of R-R potentials becomes possible.Comment: 8 pages, LaTeX, no figures. Talk presented at the 2nd Conference on
Quantum aspects of Gauge Theories, Supersymmetry and Unification, Corfu,
Greece, 21-26 September 199
New Results on the Theoretical Precision of the LEP/SLC Luminosity
We consider the error budget for the calculation of the LEP/SLC luminosity in
the Monte Carlo event generator BHLUMI4.04 from the standpoint of new
calculations of the exact result for the O(alpha) correction to the process e+
e- -> e+ e- + gamma in the low angle luminosity regime at SLC/LEP energies, for
the double bremsstrahlung effect e+ e- -> e+ e- + gamma gamma in this regime,
and for the size of the two-loop virtual correction to e+ e- -> e+ e- in this
regime in context of Yennie-Frautschi-Suura exponentiation. We find that the
error on the O(alpha**2) photonic correction can be reduced from the currently
published value 0.1% to the value 0.027%. This leads to an over-all precision
tag for the currently available program BHLUMI4.04 of 0.061%. This reduction of
the precision of the calculation is important for the final LEP1 EW precision Z
physics tests of the Standard Model.Comment: 4 pages, 3 figures, 1 table, 1998 Rochester Conference presentation,
corrected Ref. 12, improved reference to Ref. 10, corrected Ref. 1
Bhabha Process at LEP - Theoretical Calculations
In this contribution we give a short overview of the situation in the
precision calculation of the Bhabha process and we present a preliminary
numerical result on the second-order sub-leading correction to the small angle
Bhabha process.Comment: 11 pages LaTeX, 7 Postscript figures, uses amstex. Presented by S.
Jadach at Zeuthen Workshop, April 1996, Rheinsberg, Germany. Correction fixes
incorrect preprint number: no change in content
Multiple (inverse) binomial sums of arbitrary weight and depth and the all-order epsilon-expansion of generalized hypergeometric functions with one half-integer value of parameter
We continue the study of the construction of analytical coefficients of the
epsilon-expansion of hypergeometric functions and their connection with Feynman
diagrams. In this paper, we show the following results:
Theorem A: The multiple (inverse) binomial sums of arbitrary weight and depth
(see Eq. (1.1)) are expressible in terms of Remiddi-Vermaseren functions.
Theorem B: The epsilon expansion of a hypergeometric function with one
half-integer value of parameter (see Eq. (1.2)) is expressible in terms of the
harmonic polylogarithms of Remiddi and Vermaseren with coefficients that are
ratios of polynomials. Some extra materials are available via the www at this
http://theor.jinr.ru/~kalmykov/hypergeom/hyper.htmlComment: 24 pages, latex with amsmath and JHEP3.cls; v2: some typos corrected
and a few references added; v3: few references added
The Centurion 18 telescope of the Wise Observatory
We describe the second telescope of the Wise Observatory, a 0.46-m Centurion
18 (C18) installed in 2005, which enhances significantly the observing
possibilities. The telescope operates from a small dome and is equipped with a
large-format CCD camera. In the last two years this telescope was intensively
used in a variety of monitoring projects.
The operation of the C18 is now automatic, requiring only start-up at the
beginning of a night and close-down at dawn. The observations are mostly
performed remotely from the Tel Aviv campus or even from the observer's home.
The entire facility was erected for a component cost of about 70k$ and a labor
investment of a total of one man-year.
We describe three types of projects undertaken with this new facility: the
measurement of asteroid light variability with the purpose of determining
physical parameters and binarity, the following-up of transiting extrasolar
planets, and the study of AGN variability. The successful implementation of the
C18 demonstrates the viability of small telescopes in an age of huge
light-collectors, provided the operation of such facilities is very efficient.Comment: 16 pages, 13 figures, some figures quality was degraded, accepted for
publication in Astrophysics and Space Scienc
United classification of cosmic gamma-ray bursts and their counterparts
United classification of gamma-ray bursts and their counterparts is
established on the basis of measured characteristics: photon energy E and
emission duration T. The founded interrelation between the mentioned
characteristics of events consists in that, as the energy increases, the
duration decreases (and vice versa). The given interrelation reflects the
nature of the phenomenon and forms the E-T diagram, which represents a natural
classification of all observed events in the energy range from 10E9 to 10E-6 eV
and in the corresponding interval of durations from about 10E-2 up to 10E8 s.
The proposed classification results in the consequences, which are principal
for the theory and practical study of the phenomenon.Comment: Keywords Gamma rays: burst
Modelling harmonic generation measurements in solids
Harmonic generation measurements typically make use of the plane wave result when extracting values for the nonlinearity parameter, beta, from experimental measurements. This approach, however, ignores the effects of diffraction, attenuation, and receiver integration which are common features in a typical experiment. Our aim is to determine the importance of these effects when making measurements of beta over different sample dimensions, or using different input frequencies. We describe a three-dimensional numerical model designed to accurately predict the results of a typical experiment, based on a quasi-linear assumption. An experiment is designed to measure the axial variation of the fundamental and second harmonic amplitude components in an ultrasonic beam, and the results are compared with those predicted by the model. The absolute b values are then extracted from the experimental data using both the simulation and the standard plane wave result. A difference is observed between the values returned by the two methods, which varies with axial range and input frequency. (C) 2013 Elsevier B. V. All rights reserved.</p
Phenomenology of the Interplay between IR-Improved DGLAP-CS Theory and NLO ME Matched Parton Shower MC Precision
We present the current status of the application of our approach of {\it
exact} amplitude-based resummation in quantum field theory to precision QCD
calculations, by realistic MC event generator methods, as needed for precision
LHC physics.In this ongoing program of research, we discuss recent results as
they relate to the interplay of the attendant IR-Improved DGLAP-CS theory of
one of us and the precision of exact NLO matrix element matched parton shower
MC's in the Herwig6.5 environment in relation to recent LHC experimental
observations. There continues to be reason for optimism in the attendant
comparison of theory and experiment.Comment: 11 pages, 3 figures; now 12 pages, 4 figures -- explanatory material
added and title changed for publication in Phys. Lett.
GRB 010222: A burst within a starburst
We present millimeter- and submillimeter-wavelength observations and near-infrared K-band imaging toward the bright gamma-ray burst GRB 010222. Over seven different epochs, a constant source was detected with an average flux density of 3.74 ± 0.53 mJy at 350 GHz and 1.05 ± 0.22 mJy at 250 GHz, giving a spectral index α = 3.78 ± 0.25 (where F â vα). We rule out the possibility that this emission originated from the burst or its afterglow, and we conclude that it is due to a dusty, high-redshift starburst galaxy (SMM J14522 + 4301). We argue that the host galaxy of GRB 010222 is the most plausible counterpart of SMM J14522+4301, based in part on the centimeter detection of the host at the expected level. The optical/near-IR properties of the host galaxy of GRB 010222 suggest that it is a blue sub-L* galaxy, similar to other GRB host galaxies. This contrasts with the enormous far-infrared luminosity of this galaxy based on our submillimeter detection (LBol â 4 Ă 10 12 Lâ). We suggest that this GRB host galaxy has a very high star formation rate, SFR â 600 Mâ yr -1, most of which is unseen at optical wavelengths
- âŠ