|
|
Past seminars year 2006-2007 |
| 29stSept. 2006 |
Novel detector technologies at the International Linear Collider
| talk in pdf and ppt
|
| 14:30 |
Wolfgang Lohmann (DESY, Zeuthen) |
|
Abstract:
The design of a e+e- Collider for energies up to one TeV
is launched as a world-wide project. New insights are expected
for example into the origin of mass, the space-time structure
and the nature of cold dark matter in this energy range.
Measurements of the relevant processes require a new generation
of particle detectors. A world-wide R&D program for novel
detector technologies just started.
An overview will be given on the physics essentials
and the derived challenges and goals for the detector
performance.
The current status of the detector research and development
program will be reported.
|
| 13thOct. 2006 |
The LHC / ILC Connection
| talk in pdf
|
| 14:30 |
Prof. Georg Weiglein (Durham) |
|
Abstract:
Ground-breaking discoveries are expected from the experiments under
construction at the Large Hadron Collider (LHC) and those planned for
the International Linear Collider (ILC). These high-energy particle
accelerators will open up the new territory of TeV-scale physics,
allowing us to examine the very fabric of matter, space and time.
The LHC and the ILC will explore this new territory in different but
complementary ways. It will be discussed how the nature of physics
at the TeV scale can be identified using the information provided by
both machines. The interplay of the LHC and the ILC will maximise
their physics benefit.
|
| 10thNov. 2005 |
Observation of the GZK Cutoff by the HiRes Experiment
|
|
| 14:30 |
Prof. Gordon Thomson (Rutgers - New Jersey)
|
|
Abstract:
Photopion production in interactions between photons of the Cosmic
Microwave Background Radiation and ultrahigh energy cosmic ray protons is a
very strong energy-loss mechanism, and was predicted (by Greisen, Zatsepin, and
Kuzmin in 1966) to sharply suppress the cosmic ray flux above an energy of 60
EeV. The High Resolution Fly's Eye (HiRes) experiment detects cosmic ray air
showers using the fluorescence technique, and has observed this cutoff. The
details of our observation, at the five standard deviation level, will be
presented.
|
| 1stDec. 2006 |
Saturation in high-energy QCD: scaling laws and applications
| talk in pdf
|
| 11:00 |
Dr. Gregory Soyez (CEA - Saclay) |
|
Abstract:
The aim of the talk is to expose the properties of the collision amplitudes
expected from high-energy QCD. They are usually taking the form of universal
and generic scaling laws. To reach that point, I shall first introduce the
perturbative QCD equation towards high-energy, emphasising the need for
saturation and gluon-number fluctuations. Then I should explain how the
scaling laws appear as solutions to those equations and what is the physical
picture emerging from that analysis. Finally, I shall show how they apply to
physical observables such that forward particle production at the LHC.
|
| 19stDec. 2006 |
The Amanda and Icecube neutrino telescopes and the search for
cosmic steady neutrino pointlike sources
| talk in pdf
and in odp - with animations
|
| 14:30 |
Dr. Bruny Baret (IIHE) |
|
Abstract:
The Icecube neutrino telescope is currently being built in the deep ice
of the South Pole glacier. With a final size of 1km3 optimized for
TeV-PeV neutrino
detection it is already be as big as its predecessor Amanda which is
taking data since 1997.
After an overview of their science goals and status,we will turn to the
more specific subject of
pointlike sources search and statistical associated techniques.
|
| 8thDec. 2007 |
Diffractive Scattering and Parton Densities at H1
| talk in pdf
|
| 10:30 |
Dr. Matthias Mozer (Heidelberg Uni.) |
|
Abstract:
Due to the absence of hard scales, diffractive scattering in hadron
collisons is difficult to interpret in terms of QCD. Analogous processes
in ep collisions at HERA, however, allow for the detailed investigation of
diffraction. Recent studies at H1 have increased our understanding of the
QCD dynamics of diffractive scattering by determining diffractive parton
distributions with unprecedented precision.
|
| 19thJan. 2007 |
Electron and Photon Energy Calibration and High Level Trigger in the CMS
Experiment
| talk in pdf
|
| 14:00 |
Dr. L. Agostino (CERN) |
|
Abstract:The CMS experiment that is being built at CERN will study the products of
proton-proton collisions produced at the LHC at the energy of 14 TeV in
the center of mass.
An important part of the CMS physics program will consist in the search for
the Higgs boson responsible for the origin of mass. The decision to build
an electromagnetic calorimeter (ECAL) capable of high energy resolution
is strongly related with the search for the Higgs boson.
In this talk I will concentrate on the strategy that CMS will adopt to reach
the best ECAL performances and the difficulties that we need to face in
the calibration of this device. In the second part of the talk I will
concentrate on the High Level Trigger selection of electrons and photons.
Finally, I will dedicate few slides to a different topic describing the
analysis of semileptonic decays of the charm mason D^0 in the Fermilab
experiment FOCUS.
|
| 19thJan. 2007 |
High-multiplicity top quark physics at D-zero
| talk in pdf
|
| 16:00 |
Dr. F. Blekman (Imperial Coll. UK) |
|
Abstract:
The Tevatron collider at Fermi National Accelerator Laboratory
collides protons on anti protons at the current energy frontier,
almost 2 TeV. The protons collide at two different interaction
points, and at one of these the D0 detector is situated. The top
quark is the heaviest elementary particle known to man, and can only
be observed in large numbers at the Tevatron collider. A measurement
of the top quark pair production cross section in proton Tevatron
collisions is presented.
This analysis uses 405 pb-1 of data collected with the D0 detector
during 2003-2005. The analysis focuses on the case where top quarks
decay only to hadrons. These final states of six or more jets are
expected to be the bulk of top quark decays but have the disadvantage
that there is an overwhelming background that is many orders of
magnitude more frequent at the Tevatron. We will present the trigger
and analysis techniques used to separate the top quark signal from
the multijet background, which includes the use of using secondary
vertex tagging, event shape analysis and multivariate techniques.
|
| 30thJan. 2007 |
Physics results of the Pierre Auger Observatory
| talk in pdf
|
| 14:30 |
Dr. V. Van Elewyck (IPN Orsay) |
|
Abstract:
The Southern Pierre Auger Observatory (PAO), under construction in
Argentina, is now nearing completion, and the accumulating data sample has
already allowed to extract scientific results of relevance for ultra-high
energy cosmic-ray (UHECR) physics.
After a brief description of the experimental techniques used by the PAO,
I will survey the present outcomes of studies on the UHECR spectrum,
arrival directions (and in particular the anisotropy searches around the
Galactic Center) and composition (with the extraction of a limit on the
flux of UHE photons and its implications).
The PAO also has the capability to detect ultra-high energy neutrinos by
observing very inclined showers having a significant
electromagnetic component. I will briefly report on the PAO discrimination
power for such a signal, and discuss its prospective sensitivity to cosmic
neutrinos around EeV energies.
|
| 12thFeb. 2007 |
The new MadGraph/MadEvent v4 : from models to detectors in one go
| talk in pdf
|
| 14:30 |
Dr. Michel Herquet (UCL, Belgium) |
|
Abstract:
The new version of the MadGraph/MadEvent (MG/ME) MC generator is introduced
by emphasizing its integration in a complete analysis chain ranging from new
theoretical models implementation to detector simulation. A few online
computations will be executed to illustrate the many MG/ME functionalities
and discuss the differences with respect to the "old-fashioned" event
generation programs.
|
| 13thFeb. 2007 |
Study of neutrino interactions and background estimation in the OPERA
Detector
| talk in pdf
|
| 14:30 |
Dr. Jozsef Janicsko-Csathy (Universite de Neuchatel, CH) |
|
Abstract:
As the OPERA detector is coming close to completion it is increasingly
important to concentrate on the analysis of the expected data. After an
introduction to the general layout of the detector, in this talk I will
present background evaluation and detector efficiency estimations, based on
MC simulation, in the context of the sensitivity to neutrino oscillations
after five years of data-taking. I will also discuss problems related to
tracking and vertex finding with some suggested solutions. With the first
neutrinos detected by OPERA the real life application of this methods is
within sight.
|
| 16thFeb. 2007 |
Diffraction at HERA and the Very Forward Proton Spectrometer
| talk in pdf
|
| 10:00 |
Dr. X. Janssen (IIHE - ULB) |
|
Abstract:
I will review recent results on lepton-proton diffractive scattering
from the H1 experiment, in particular on vector meson production,
e + p -> e + VM + p and inclusive deep-inelastic scattering,
e + p -> e + X + p, and their interpretation in terms of QCD.
The Very Forward Proton Spectrometer installed since 2003 allows to
select cleanly diffractive events by tagging directly the outgoing
proton. After reviewing the history and the status of the project, I
will present an insight on first data and prospects for physics
measurements.
|
| 9thMar. 2007 |
Threshold resummation for slepton pair production at hadron colliders
| talk in pdf
|
| 14:30 |
Dr. Benjamin Fuks (Lab. de Physique Subatomique et de Cosmologie, Grenoble) |
|
Abstract:
The cross sections for supersymmetric (SUSY) particle pair production at hadron
colliders have been studied in the past at next-to-leading order of full
perturbative QCD, including not only QCD radiative corrections, but also
SUSY-QCD corrections coming from virtual loops of squarks and gluinos. We focus
on Drell-Yan like slepton-pair and slepton-sneutrino associated production, and
extend previous calculations to the case of mixing squarks in the virtual loop
contributions. Then, we employ the usual Mellin N-space resummation formalism
with the minimal prescription for the inverse Mellin-transform, and improve it
by resumming 1/N-suppressed and a class of N-independent universal
contributions. Numerically, our results increase the theoretical cross sections
by 5 to 15% with respect to the NLO predictions and stabilize them by reducing
the scale dependence from up to 20% at NLO to less than 10% with threshold
resummation.
|
| 30thMarch 2007 |
Optimising of Design Parameters of the TESLA Vertex Detector and
Search for Events with Isolated Leptons and Large Missing Transverse
Momentum with the ZEUS-Experiment (HERA II)
| talk in pdf
|
| 14:30 |
Dr. Volker Adler (DESY) |
|
Abstract:
In this seminar, a search for events with isolated leptons and large missing
transverse momentum at HERA is presented. Data with an integrated luminosity of
40.76 pb-1 of
e+p-collisions collected with the ZEUS detector
at a CMS energy of 318 GeV during the HERA II running period in the years 2003
and 2004 were used. Some extensions of the SM contain FCNC processes at tree
level, which could lead to a significantly enhanced rate of singly produced
t-quarks at HERA (e±p →
e±tX). The signature of interest originates
from the decay t → bW+ with a subsequent
leptonic decay of the W-boson (W+ →
e+νe ,
μ+νμ ,
τ+ντ). After
the final selection, one event was found in data in the combined e- and
μ-channels, where 1.27±0.15 were expected from SM predictions.
The selection efficiency in these channels was
13.4-0.8+1.8% for a
t-quark mass of 175 GeV. In combination with independent searches in HERA
I data in both, the leptonic and hadronic channel, limits on the FCNC couplings
through photon and Z-boson exchange were derived. The NLO limit
κtuγ <
0.160-0.012+0.014 at 95% CL
for a t-quark mass of 175 GeV is the most stringent so far. Together with
the most stringent limit on vtuz of 0.37, an upper
cross section limit of σsingle t <
0.186-0.012+0.029 pb was
obtained. Also a limit on the cross section of single W-boson production
of σsingle W <
1.54-0.41+0.67 pb was
obtained at 95% CL.
Also a simulation study to optimise design parameters of a MAPS based vertex
detector for a future ILC is presented in this seminar. The study was based on
the TESLA TDR. In order to evaluate the effect of different design options for
the vertex detector on the physics performance of the whole detector, the
reconstruction of the t-quark mass from the signal process
e+e- → tt in the
all-hadronic decay channel was used. The fast simulation program SGV was
equipped with a neural-network based heavy-flavour tagging, where the
b-tagging achieved a purity of 86% at an efficiency of 70%. It was found
that the reconstruction of the t-quark mass was not successful due to
resolution limitations in SGV. Nevertheless, today the combination of SGV and
heavy-flavour tagging is used internationally for vertex detector design studies
using other analysis branches.
|
| 11stMay 2007 |
Search for sources of high energy cosmic rays with the ANTARES neutrino
telescope and the Auger observatory
| talk in pdf
|
| 14:30 |
Dr. Jelena Petrovic (NIKHEF) |
|
Abstract:
Both ultra-high energy cosmic rays and neutrinos do not suffer from the
deflection by interstellar and intergalactic magnetic fields and their
observed arrival directions point back to their sources.
If the arrival direction of an ultra-high energy cosmic ray observed by
the Auger observatory is assumed to be a point source, one can search
for neutrinos coming from the same direction with the ANTARES telescope.
In this way the neutrino background is suppresed substantially.
Additionally, the significance of ANTARES neutrino observations can be
further improved if they are performed in directions of inclined events
observed by Auger, since those are most likely triggered by neutrinos.
|
| 16stMay. 2007 |
Electrons at ATLAS/LHC
| talk in pdf
|
| 11:00 |
Dr. Mohamed Aharrouche (LAPP - Annecy) |
|
Abstract:
The ATLAS detector, currently being installed at CERN is designed
to make precise measurements of 14 TeV proton-proton collisions at
the LHC. The reconstruction of the electrons and photons is one of
the main keys of the LHC physics analysis. The ATLAS calorimeter
has to provide an accurate measurement their energy and position.
The design of the electromagnetic calorimeter was constrained by
the benchmark channels H-->gamgam (80 GeV < mH <130 GeV) and
H --> ZZ-> 4e(120 GeV< mH < 500 GeV).
I'll present a method for calibrating the energy measurement of electrons
based on Geant4 Monte Carlo simulation , and the calorimeter performance
in the 2004 Combined Test Beam. In the second part I'll talk about the
forward electron reconstruction with ATLAS necessary to measure the
fwd/bwd charge asymmetry in the channel pp --> Z-->e+e-.
|
| 18thMay. 2007 |
Evidence for Single Top Quark Production at the Tevatron
| talk in pdf
|
| 14:30 |
Dr. Christian Schwanenberger (Univ. of Manchester) |
|
Abstract:
An overview of the search for the production of single top quarks in proton
anitproton collisions at a center of mass energy of 1.96 TeV will be presented
using a data set of ~1 fb-1 recorded by the CDF and D0 collaborations. First
evidene for single top quark production was reported by the D0 collaboration
which allows a first direct measurement of the CKM matrix element V_tb.
|
Past seminars in:
[2003-2004]
[2004-2005]
[2005-2006]
[2006-2007]
[2007-2008]
[2008-2009]
|
