3,068 research outputs found
Precision tests of the Electroweak interactions at e+e- collisions
This paper is an updated version of the lectures given at the XXIX
International Meeting on Fundamental Physics in Sitges, Barcelona (February
2000). The measurements perforned at LEP and SLC have substantially improved
the precision of the test of the Minimal Standard Model. The precision is such
that there is sensitivity to pure weak radiative corrections. This allows to
indirectly determine the top mass (m_t = 180 +- 10GeV), the W-boson mass (M_W =
80.375 +- 0.022GeV), and to set an upper limit on the Higgs boson mass of
196GeV at 95% confidence level.Comment: 19 pages, 6 figures, XXIX International Meeting on Fundamental
Physics 5-9 February 2001, Sitges, Barcelon
Precision test of the Standard Model from Z physics
The measurements performed at LEP and SLC have substantially improved the precision of the test of the Minimal Standard Model. The precision is such that there is sensitivity to pure weak radiative corrections. This allows to indirectly determine the top mass (\mt=1618 GeV), the W-boson mass of 262 GeV at 95% confidence level
Study of Muon-Pair Production at centre-of-mass energies from 20 to 136 GeV with the ALEPH detector
Physics Opportunities with the FCC-hh Injectors
In this chapter we explore a few examples of physics opportunities using the
existing chain of accelerators at CERN, including potential upgrades. In this
context the LHC ring is also considered as a part of the injector system. The
objective is to find examples that constitute sensitive probes of New Physics
that ideally cannot be done elsewhere or can be done significantly better at
theCERN accelerator complex. Some of these physics opportunities may require a
more flexible injector complex with additional functionality than that just
needed to inject protons into the FCC-hh at the right energy, intensity and
bunch structure. Therefore it is timely to discuss these options concurrently
with the conceptual design of the FCC-hh injector system.Comment: 13 pages, chapter 5 in Physics at the FCC-hh, a 100 TeV pp collide
Electroweak Working Group Report
The report summarizes the results of the activities of the Working Group on
Precision Calculations for the Z Resonance at CERN during 1994.Comment: 158 Latex, including 37 figures (27 eps figures), 30 tables; The
report is part of: D. Bardin, W. Hollik, G. Passarino (eds.), Reports of the
working group on precision calculations for the Z resonance, CERN 95-03 (31
March 1995
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions
Data taken with the ALEPH detector at LEP1 have been used to search for gamma
gamma production of the glueball candidates f0(1500) and fJ(1710) via their
decay to pi+pi-. No signal is observed and upper limits to the product of gamma
gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have
been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) <
0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV
at 95% confidence level.Comment: 10 pages, 3 figure
Search for CP Violation in the Decay Z -> b (b bar) g
About three million hadronic decays of the Z collected by ALEPH in the years
1991-1994 are used to search for anomalous CP violation beyond the Standard
Model in the decay Z -> b \bar{b} g. The study is performed by analyzing
angular correlations between the two quarks and the gluon in three-jet events
and by measuring the differential two-jet rate. No signal of CP violation is
found. For the combinations of anomalous CP violating couplings, and , limits of \hat{h}_b < 0.59h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st
Opposite-side flavour tagging of B mesons at the LHCb experiment
The calibration and performance of the oppositeside
flavour tagging algorithms used for the measurements
of time-dependent asymmetries at the LHCb experiment
are described. The algorithms have been developed using
simulated events and optimized and calibrated with
B
+ âJ/ÏK
+, B0 âJ/ÏK
â0 and B0 âD
ââ
Ό
+
ΜΌ decay
modes with 0.37 fbâ1 of data collected in pp collisions
at
â
s = 7 TeV during the 2011 physics run. The oppositeside
tagging power is determined in the B
+ â J/ÏK
+
channel to be (2.10 ± 0.08 ± 0.24) %, where the first uncertainty
is statistical and the second is systematic
Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a
centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The
value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08
^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical,
the second systematic and the third is associated to the ratio of fragmentation
fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/-
0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be
(3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.Comment: 15 pages, 1 figure, 2 table
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