|
Gupta |
Pooja |
University of Delhi |
Pooja.Gupta@cern.ch |
|
We present simulation results of $\gamma$ + Jet
analysis using CMS (Compact Muon Solenoid)
Object-Oriented software at the LHC center of mass energy ($\sqrt{s}$=14 TeV).
The study of direct photon production helps in validating the perturbative quantum chromodynamics
(pQCD) and constraining the gluon distribution of
nucleons. Direct photon processes also represent a major contribution in
estimating background to other Standard Model (SM) processes and signals of
new physics. Thus these processes need to be understood precisely in the new
energy regime mentioned above. In this work, we have done a detailed study of
the complete GEANT4 simulated events of $\gamma$ + jet generated with Pythia and the related background processes at $\sqrt{s}$=14 TeV.
Isolation cuts have been defined for the direct photon which improves the
signal to background ratio by $\sim25\%$ as compared to previous studies done
in CMS. This details of this work can be seen in CMS
NOTE 2007/004. |
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|
Aharrouche |
Mohamed |
LAPP/Université
de Savoie/in2p3/CNRS |
aharrouc@lapp.in2p3.fr |
|
We present here the results of our first study on
the determination of the effective weak mixing angle from the measurement of
the Forward-Backward Asymmetry in Z-->e+e- events
at LHC. The statistical precision (10^-4) on $\sin^{2}\theta^{lept}_{eff}$ found is better
than the current results. To reach such a precision it will be necessary to
identify the electrons in the forward region of the ATLAS detector with an efficiency better than 50% and an electron-jet
rejection more than 100. |
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|
Witek |
Mariusz |
Institute of Nuclear Physics PAN |
Mariusz.Witek@ifj.edu.pl |
|
Title: Study of four-fermion neutral currents
processes in the DELPHI experiment at LEP. Abstract: The four-fermion neutral
currents processes were studied in the DELPHI experiment at LEP collider. The
results are based on data collected in 1997-2000 at the energy range 183-209 GeV. The final results for ZZ pair production and single
Z/$\gamma^*$ production were already published. The results of the analysis
of $Z \gamma^*$ production and study of anomalous triple neutral bozon couplings are submitted and accepted for
publication respectively. Within the expermental
uncertainties, the results confirm the predictions of the electroweak theory. |
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|
Lavagno |
Andrea |
Politecnico di Torino |
andrea.lavagno@polito.it |
|
Non-conventional statistical effects in high energy
heavy-ion collisions Starting from the presence of non-ideal plasma effects
due to strongly coupled plasma in the early stage of relativistic heavy-ion
collisions, we investigate, from a phenomenological point of view, the
relevance of non-conventional statistical mechanics effects on the
interpretation of the experimental observables in relativistic heavy-ions
collisions. We study the relativistic thermodynamics and the equation of
state in the hadronic and in the quark-gluon plasma
phase in the framework of the generalized non-extensive thermodynamics,
strictly connected to the presence of long range forces, memory effects. In
this context, we show that the broad rapidity shape measured at RHIC can be very
well reproduced in the framework of a non-linear relativistic Fokker-Planck
equation which incorporates non-extensive statistics and anomalous diffusion. |
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|
LE |
Duc
Ninh |
CERN/LAPTH |
ldninh@cern.ch |
|
We consider the mechanism to produce the SM Higgs
associated with a bottom-antibottom pair at the
Large Hadron Collider (LHC), in particular we investigate the one loop
electroweak correction to the process $gg\rightarrow b\bar{b}H$ in the SM. We find that the NLO
electroweak correction to the total cross section at the tree level is small,
about $-3\%$ if the Higgs mass is $120$GeV. In the limit of vanishing bottom
Yukawa coupling the cross section is generated solely at the loop level. This
contribution is very small at $M_H\sim 120$GeV and
increases with growing Higgs mass, reaching about $+17\%$ of the total cross
section when the Higgs mass is about $150$GeV. |
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|
Machado |
Ana
Amelia |
CBPF |
amelia@cbpf.br |
|
In this work the S-wave component of the $K\pi$
amplitude from decay of $D^+\to K^-\pi^+\pi^+$ it is directly measured. The
data come from the Fermilab E831/FOCUS experiment.
The amplitude measurement is made using the partial wave analysis without any
preliminary assumption about the nature of the S-wave component of the $K\pi$
system. The phase and magnitude of the S-wave amplitude are generic functions
to be determined directly through the Dalitz plot
fit. For the sake of comparison, our results the same decay is analised using the isobar model, which is the standard
way to analise the Dalitz
plot. The data fit obtained with the partial wave analysis is better than the
data fit from the isobar model. The phase variation with respect to the
invariant mass $K\pi$ is compared with the measurement of the phase $\delta_{I=1/2}^0 (m_{K\pi})$ from $K\pi\to K\pi$ scattering. The
difference between both analysis is discussed
considering: a difference in the composition of the isospin
components I=1/2 and I=3/2 of the $K\pi $ system between $D^+$ decay and the
$K\pi\to K\pi$ scattering; and the final state interaction involving all
particles from decay. |
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|
ISHINO |
Masaya |
ICEPP, The university of Tokyo |
Masaya.Ishino@cern.ch |
|
In the end cap region of the ATLAS muon detector, the technology of TGC (Thin Gap Chamber)
is placed for triggering high momentum muons
because of its high rate capability and fast response to identify the
crossing bunch of LHC. TGC is assembled as 6 wheels having diameter of 25m,
and each wheel consists of 12 sectors. In total 72 sectors are assembled on
surface building at CERN and its scheme and summary of test results against
320k channels are presented. Also the the readiness
of both detector and electronics to work as LVL1 muon
trigger system is shown throught the result of TGC
wheel commissioning with using cosmic-ray in the pit. |
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|
Suleymanov |
Mais
|
COMSATS
Institute of Information Technology, Islamabad |
mais_suleymanov@comsats.edu.pk |
|
Percolation cluster formation at ultrarelativistic
heavy ion collisions. M. K. Suleymanov, E. U. Khan,
K. Ahmed, M. Q .Haseeb, F. Tahir,
Ya. H. Huseynaliyev
Department of Physics COMSATS Institute of Information Technology We discuss
that the experimental study of percolation cluster formation and appearance
of the critical transparency of the strongly interacting matter can give the
information about the onset state of the deconfinement. |
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|
TRINH |
Thi Nguyet |
Centre
de Physique des Particules de Marseille |
trinh@cppm.in2p3.fr |
|
Searches for New Physics at HERA The high energy
program of the HERA ep collider ended in march
2007. Along the whole HERA program, a total integrated luminosity of around 0.5 fb-1 has been collected by the H1
experiment. In this context, the most recent results from H1 about searches
for new phenomena will be presented. New searches for excited electrons and
neutrinos have been performed using the complete HERA I and II data samples
and the limits derived are presently the most stringent for high mass excited
leptons, in good complementarity with Tevatron and
LEP results. Isolated lepton and multi-leptons topologies have also been
investigated using the full H1 luminosity. An excess of events containing
isolated high transverse energy electrons or muons
and large missing transverse momentum compared to the Standard Model
prediction is observed in the $e^{+}$ data. At large
hadronic transverse momentum $P_{T}^{X}
>$ 25 GeV, it corresponds to a "3
$\sigma$" deviation. Finally, all event topologies involving isolated
electrons, photons, muons, neutrinos and jets with
high transverse momenta have been investigated in a model-independent search.
Deviations from the Standard Model prediction have been looked for and
quantified using a dedicated statistical algorithm. This is the broadest
range signature based search done at a collider. |
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|
Bluj |
Michal |
Soltan Institute for Nuclear Studies, Warsaw |
mbluj@fuw.edu.pl |
|
"A study of angular correlations in
H->ZZ->4l" This poster shows a study of a possible measurement at
the CMS detector of the CP-parity of the Higgs boson coupling HZZ. The study
is performed using angular correlations in the H->ZZ->2e2mu process,
which is a "golden plated channel" for Higgs boson searches at LHC.
It is shown that a measurement of the xi-parameter describing a generalized
HZZ coupling will be feasible at CMS. The precision of the measurement is
sufficient for determination of CP-parity of the Higgs boson, in particular
to distinguish between the scalar and pseudoscalar
Higgs bosons. |
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|
Guedes |
Renato |
Centro
de Física Teórico e Computacional da Universidade
de Lisboa |
renato@cii.fc.ul.pt |
|
We study the effects of dimension six effective
operators on the flavour violating production and
decay of leptons at the International Linear Collider. We present an analysis
of the feasibility of their observation at the ILC. |
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|
BRUN |
Pierre |
LAPP |
brun@lapp.in2p3.fr |
|
Indirect searches for Dark Matter with AMS02 : AMS02 is a multi-purpose spectrometer with
superconducting magnet, designed for 3 years of data taking abroad the
international Space Station. Its high performance regarding particle
identification and energy measurement will allow performing indirect searches
for dark matter (DM) in different channel simultaneously: gamma rays,
positrons, antiprotons and hopefully antideuterons.
A new spectrum generator, based on the public package micrOMEGAs
is being developed for the computation of those signals. It includes cross
section computations, dark halo modelling and
charged particles Galactic propagation handle. This tool is presented,
together with a novel method for the quantitative prediction of boost
factors. These are expected to be caused by DM substructures, a specific
class of which is considered. We show that DM spike formation around
intermediate mass black holes can lead to dramatic enhancement of the
signals. These studies allow to determine the AMS02
sensitivity to new physics, which is eventually presented. |
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|
Pate |
Stephen |
New
Mexico State University |
pate@nmsu.edu |
|
The data collected from the collision of polarized
protons at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National
Laboratory is just beginning to yield results, particularly in constraining
the gluon contribution to the spin of the proton. After a long program of
commissioning the injection, storage, acceleration and manipulation of
polarized protons in the two storage rings, the main course of physics
results will now begin to become available in the next few years. The
upcoming spin physics program at RHIC will explore: the polarization of glue
in the proton via the production of pions, heavy
flavor, jets and prompt photons, including di-jet and $\gamma$-jet
correlations; the polarization of $u$, $\bar{u}$ $d$ and $\bar{d}$ quarks via
$W$-production in $pp$ collisions at $\sqrt{s}=500$ GeV, as well as
via the Drell-yan process and the production of
prompt $\gamma\gamma$ pairs; and a wide range of transverse spin phenomena.
This program of measurements, to be completed by 2012, will provide a wealth
of data on polarized parton distribution functions
and address other critical issues in nucleon structure. |
|||
|
Osuna |
Carlos |
IFAE |
Carlos.Osuna@ifae.es |
|
"Implementation and performance of the Tau
Trigger in the ATLAS experiment" Triggering with hadronic
taus at the LHC is a difficult task due to the high
rate and occupancy of the events. However, it is worth to trigger on taus. This trigger is used in many physics channels such
as VBF H->tau tau, charged Higgs, etc. In order
to select these events, the tau vertical trigger is organized in three
trigger levels: first (LVL1), second (LVL2) and third (Event Filter -EF-)
level triggers. The LVL1 trigger is hardware based and identifies a narrow
jet in the calorimeter. It reduces the rate of accepted tau candidates from
40 MHz to about 1 kHz. Both LVL2 and EF are software based triggers which
select tau candidates analyzing calorimeter clusters and tracks reconstructed
in the inner detector. The goal of LVL2 and EF in the tau slice is to reduce
the event rate to about 10 Hz. This contribution will present a detailed
description of the algorithms used in the tau trigger and their performance
in terms of event rates, signal efficiency and timing. Different run
conditions will be considered, including luminosity and occupancy of the
detector. The effects in relevant physics and background samples will be
evaluated. |
|||
|
Skottowe |
Hugh |
University of Cambridge |
skottowe@hep.phy.cam.ac.uk |
|
LHCb, one of the experiments of the Large Hadron Collider at CERN, has
been designed for the purpose of high-precision measurements of the
parameters of the CKM quark-mixing matrix, and for studies of rare B-hadron
decays. An essential part of the experiment is an efficient system of
particle identification, effective over a momentum range of ~1 to ~150 GeV/c. For this we use a set of two ring imaging
Cherenkov detectors and three Cherenkov radiators: C4F10 and CF4 gases, and
Silica aerogel. Cherenkov photons in a wavelength range of 200-600nm are to
be detected by 484 Hybrid Photon Detectors (HPDs), each consisting of 1024
pixels and covering a total area of 2.6m**2, in four planes. The general
status of the LHCb RICH detectors will be
described, and the work in progress on commissioning and preparing for LHC
beam and data-taking will be summarized. |
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|
Stathes |
Paganis |
On behalf of the ATLAS H->4l Analysis Group.
Actual Speaker to be nominated. |
paganis@mail.cern.ch |
|
The ATLAS detector, currently being installed at
CERN, is designed to search for new physics and to make precise measurements,
by colliding proton beams at the unprecedented center of mass energy of 14 TeV at the Large Hadron Collider (LHC). Central to these
searches is the discovery of the Standard Model Higgs boson, one of the most
striking experimental signatures of which is the production of four isolated
prompt charged leptons. In this paper, the Standard Model Higgs boson
discovery potential through its observation in the H->ZZ*->4-lepton
(electron and muon) final state is investigated in
a wide mass range, starting from 120 GeV/c2. The
trigger, offline identification and precise momentum measurement of leptons
are performed using the combined information from the inner tracker and the muon spectrometer, and of energy
deposition measurements in the calorimeters. The performance of the relevant
sub-detectors is studied through a Geant4 based simulation of the ATLAS
detector, including samples of signal and background processes. The selection
analysis is performed by exploiting various techniques, in order to obtain
optimal discrimination between the signal and background processes. The
impact of a misaligned/miscalibrated detector and
the effects of pile-up and cavern background on the analysis performance are
also investigated. |
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|
De
La Cruz Burelo |
Eduard |
University of Michigan |
Eduard.Burelo@cern.ch |
|
B Physics at Dzero We
present the latest results on B physics from the D0 collaboration at the Tevatron collider. The large cross-section of b quark
production and the diversity of b hadron species available at the Tevatron energy allow the D0 collaboration to perform
exciting measurements such as lifetimes, mixing, and rare decay studies. In
many cases these are either world's first or world's
best measurements. |
|||
|
Beauceron |
stephanie |
CERN |
stephanie.beauceron@cern.ch |
|
The CMS electromagnetic calorimeter (ECAL) comprises
about 76000 Lead Tungstate scintillating crystals. The barrel part of ECAL
consists of 36 supermodules, each containing 1700 crystals . During summer 2006, nine of these supermodules were exposed to an electron beam, allowing
us to determine initial intercalibration
coefficients for all their crystals. Different methods of intercalibration
based either on single crystal response or on matrices of
crystals (as will be used in CMS) have been used and compared. The
calorimeter response and the energy resolution have been measured over the
whole area of the supermodules. These measurements
will be presented, showing that the calorimeter performance is in agreement
with the design resolution. |
|||
|
Petran |
Michal |
Faculty of Nuclear Sciences and Physical Engineering |
michal.petran@seznam.cz |
|
One of the many phenomena to be studied on the LHC
is the proton-antiproton asymmetry in heavy-ion and pp
collisions. We will be able to study proton stopping in the collision and
their emission in plane perpendicular to the beam axis. Measurement of this
observable will be possible with the upcoming ALICE detector at energies up
to 14 TeV in pp and 5.5 ATeV in Pb-Pb collisions.
Before the detector will be ready, simulations are done in the AliRoot framework. During this preparation for the real
data, proper analysis tools have to be ready. Predictions of the value of
proton-antiproton yields asymmetry can be made. |
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|
Panikashvili |
Natalia |
Technion, Israel Institute of Technology |
Natalia.Panikashvili@cern.ch |
|
We present a new measurement of the Lambda_b lifetime through the exclusive decay channel Lambda_b to J/psi(mu+ mu-)Lambda(p pi-) and a
complementary measurement of the B0 lifetime in the decay B0 to J/psi(mu+mu-)K0_S(pi+pi-). We also
present the lifetime ratio of tau(Lambda_b)/tau(B0) based on these results. The measurement
was done in the D0 experiment, based on an integrated luminosity of 1.2 fb-1. The measurement of the b hadron lifetime is
very important to understand the influence of the light quarks in b hadron
decays. At the leading order, Heavy Quark Effective Theory predicts the
lifetime of all b hadrons to be the same, since the light quarks are
considered spectators. Including the interactions between the b quark and the
light quark, the lifetime of b hadrons should satisfy the following relation:
tau(B+)>=tau(B0)~tau(B_s)>tau(Lambda_b)>>tau(B_c). We
found that the measurement of the Lambda_b lifetime
is consistent with the world average and the ratio of Lambda_b
and B0 lifetimes is consistent with the most recent theoretical predictions. |
|||
|
Cepila |
Jan |
Faculty of nuclear sciences and physical
engineering, Czech technical university |
jan.cepila@cern.ch |
|
Currently, the most successful particle theory is
Standard Model. It explains the basic phenomena of interactions between
particles. Almost all particle physics experiments are dedicated to the
verification or even extension of this model. The Standard Model will be
tested in new energetic region in experiments at the LHC in near future. Very
important process for such tests is Z boson production. Both components of
Standard Model (QCD and GWS theory) will be tested. Mainly, we will insist on
the Drell-Yan production of lepton pair via Z
boson. Appropriate theoretic framework is also presented for better
understanding of the whole process. This work is devoted to the study of kine- matic variables of Z
boson created in pp interactions on kinematic cuts
applied on its secondaries. The invariant mass,
rapidity and transverse momentum were chosen as representative variables for
this process. Decay channel Z-> e+e- is investigated. |
|||
|
Sowinski |
James |
Indiana
University Cyclotron Facility |
sowinski@indiana.edu |
|
Dissecting the Proton's Spin with Polarized Proton
Collisions at RHIC -- In addition to discovering a new form of matter in
Au-Au collisions the Relativistic Heavy Ion Collider is also the world's
first polarized proton collider. An important part of the program is to
investigate the polarization of the partons in the
proton via hard partonic scattering. Spin dependent
inclusive jet yields from such scattering are sensitive to the gluon
polarization via quark-gluon and gluon-gluon scattering. Results from 2005 at
root(s)=200 GeV for
inclusive jets from STAR and inclusive pi0s from Phenix
are beginning to provide new significant constraints on deltaG,
the first moment of the gluon helicity distribution.
Increased luminosity, polarization and detector coverage in 2006 will allow a
first glimpse of the x dependence of deltaG via
particle correlation measurements such as di-jets and photon-jets. Results from
2005 and progress on 2006 analyses will be presented. |
|||
|
Noble |
Anthony |
Queen's University |
potato@snolab.ca |
|
The Status of SNOLAB, a new international facility
for underground science. A new facility for astroparticle
physics, SNOLAB, is currently nearing completion. This new facility will
provide the infrastructure support required for next generation solar
neutrino detectors, dark matter search experiments and neutrinoless
double beta decay detectors. The status of this facility, the physics scope
being targeted, the infrastructure available, and the initial physics program
under consideration will be presented. |
|||
|
Bona |
Marcella |
LAPP,
Annecy |
bona@lapp.in2p3.fr |
|
We present the update of the Unitarity
Triangle analysis in the Standard Model. Combining the direct measurements on
sides and angles of the Unitarity Triangle, we
determine the values of the CKM parameters rhobar
and etabar. We discuss the agreement of the current
measurements and the indirect determinations from the rest of the fit. Then
we generalize the analysis to account for the presence of physics behyond the Standard Model. We discuss the current
model-independent bounds on NP contributions to K-Kbar,
D-Dbar and Bq-Bq bar (q=d,s) mixing processes. This
information is then translated into a lower limit on the probed scale of New
Physics. We consider several scenarios, such as a New Physics with generic flavour structure, NMFV, as well as MFV with low,
moderate or large values of tanbeta. |
|||
|
CHABAB |
Mohamed |
LPHEA,
Cadi-Ayyad University |
mchabab@ucam.ac.ma |
|
Title: Charged Higgs Bosons decays H^\pm \to W^\pm
(\gamma, Z) in MSSM. ************************************************************************************************************************
We study the complete one loop contribution to $H^\pm\to W^\pm V$, $V= Z,
\gamma$, in the Minimal Supersymmetric Standard
Model (MSSM). We evaluate the MSSM contributions taking into account $B\to
X_s\gamma$ constraint as well as experimental constraints on the MSSM
parameters. We found that in the intermediate range of $\tan\beta \la 10$ and
for large $A_t$ and large $\mu$, where lightest
stop becomes very light and hence squarks
contribution is not decoupling, the branching ratio of $H^\pm \to W^{\pm} Z$ can be of the order $10^{-3}$, while the
branching ratio of $H^\pm \to W^{\pm} \gamma$ is of the order $10^{-5}$. We
also discuss the impact of the CP violating phases of Soft SUSY parameters
and show that they can modify the branching ratio by about one order of
magnitude. *************************************************************** |
|||
|
BEsNIER |
MAGALI |
LAPP |
magali.besnier@lapp.in2p3.fr |