4,186 research outputs found
Comparison of Horace and Photos Algorithms for Multi-Photon Emission in the Context of the W Boson Mass Measurement
The W boson mass measurement is sensitive to QED radiative corrections due to
virtual photon loops and real photon emission. The largest shift in the
measured mass, which depends on the transverse momentum spectrum of the charged
lepton from the boson decay, is caused by the emission of real photons from the
final-state lepton. There are a number of calculations and codes available to
model the final-state photon emission. We perform a detailed study, comparing
the results from the Horace and Photos implementations of the final-state
multi-photon emission in the context of a direct measurement of the W boson
mass at the Tevatron. Mass fits are performed using a simulation of the CDF II
detector
Black Hole Relics in Large Extra Dimensions
Recent calculations applying statistical mechanics indicate that under the assumption of compactified large extra dimensions a black hole might evolve into a (quasi-)stable state with mass close to the new fundamental scale . Black holes and therefore their relics might be produced at the {\sc LHC} in the case of extra-dimensional topologies. In this energy regime, Hawking's evaporation scenario is modified due to energy conservation and quantum effects. We reanalyse the evaporation of small black holes including the quantisation of the emitted radiation due to the finite surface of the black hole. It is found that observable stable black hole relics with masses are formed which can be identified by a delayed single jet with a corresponding hard momentum kick to the relic and by ionisation, e.g. in a TPC
Search for TeV -rays from H1426+428 during 2004-07 with the TACTIC telescope
The BL Lac object H1426+428 () is an established source of TeV
-rays and detections of these photons from this object also have
important implications for estimating the Extragalactic Background Light (EBL)
in addition to the understanding of the particle acceleration and -ray
production mechanisms in the AGN jets. We have observed this source for about
244h in 2004, 2006 and 2007 with the TACTIC -ray telescope located at
Mt. Abu, India. Detailed analysis of these data do not indicate the presence of
any statistically significant TeV -ray signal from the source
direction. Accordingly, we have placed an upper limit of
on the integrated
-ray flux at 3 significance level.Comment: 11 pages, 5 figures accepted for publication in Journal of Physics G:
Nuclear and Particle Physic
Very High Energy gamma-ray observations of Mrk 501 using TACTIC imaging gamma-ray telescope during 2005-06
In this paper we report on the Markarian 501 results obtained during our TeV
-ray observations from March 11 to May 12, 2005 and February 28 to May
7, 2006 for 112.5 hours with the TACTIC -ray telescope. During 2005
observations for 45.7 hours, the source was found to be in a low state and we
have placed an upper limit of 4.62 10 photons cm
s at 3 level on the integrated TeV -ray flux above 1 TeV
from the source direction. However, during the 2006 observations for 66.8h,
detailed data analysis revealed the presence of a TeV -ray signal from
the source with a statistical significance of 7.5 above
1 TeV. The time averaged differential energy spectrum of the
source in the energy range 1-11 TeV is found to match well with the power law
function of the form () with and .Comment: 16 pages and 8 Figures Accepted for publication in the Journal of
Physics
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