3,389 research outputs found

### Model Independent Extra-dimension signatures with ATLAS

The generic missing transverse energy signals at LHC for theories having
large extra dimensions are discussed. Final states of jets plus missing energy
and photons plus missing energy are simulated in the ATLAS detector. The
discovery limit of LHC and the methods to determine the parameters of the
underlying model are discussed.Comment: 29 page

### High-Mass Supersymmetry with High Energy Hadron Colliders

While it is natural for supersymmetric particles to be well within the mass
range of the large hadron collider, it is possible that the sparticle masses
could be very heavy. Signatures are examined at a very high energy hadron
collider and an very high luminosity option for the Large Hadron Collider in
such scenarios

### Study of stop and sbottom at LHC

In supersymmetric models a gluino can decay into $tb\tilde{\chi}^{\pm}_1$
through a stop or a sbottom. The decay chain produces an edge structure in the
$m_{tb}$ distribution. Monte Carlo simulation studies show that the end point
and the edge height would be measured at the CERN LHC by using a sideband
subtraction technique. The stop and sbottom masses as well as their decay
branching ratios are constrained by the measurement. We study interpretations
of the measurement.Comment: 3 pages, 2 eps files, style files are included, talk at PASCOS'03,
Mumbai, India, January 3-8, 200

### A Consistent Prescription for Combining Perturbative Calculations and Parton Showers in Case of Associated Z b anti-b Hadroproduction

This paper presents the method of combining parton shower formalism with
perturbative calculations (matrix elements) in form of a Monte-Carlo algorithm
for the process g g -> Z b anti-b,consistenlty including the heavy quark masses
and overlap removal.Comment: accepted by JHEP, revised according to suggestions from JHEP refere

### On Time-Space Noncommutativity for Transition Processes and Noncommutative Symmetries

We explore the consequences of time-space noncommutativity in the quantum
mechanics of atoms and molecules, focusing on the Moyal plane with just
time-space noncommutativity ($[\hat{x}_\mu ,\hat{x}_\nu]=i\theta_{\mu\nu}$,
\theta_{0i}\neqq 0, $\theta_{ij}=0$). Space rotations and parity are not
automorphisms of this algebra and are not symmetries of quantum physics. Still,
when there are spectral degeneracies of a time-independent Hamiltonian on a
commutative space-time which are due to symmetries, they persist when
\theta_{0i}\neqq 0; they do not depend at all on $\theta_{0i}$. They give no
clue about rotation and parity violation when \theta_{0i}\neqq 0. The
persistence of degeneracies for \theta_{0i}\neqq 0 can be understood in terms
of invariance under deformed noncommutative ``rotations'' and ``parity''. They
are not spatial rotations and reflection. We explain such deformed symmetries.
We emphasize the significance of time-dependent perturbations (for example, due
to time-dependent electromagnetic fields) to observe noncommutativity. The
formalism for treating transition processes is illustrated by the example of
nonrelativistic hydrogen atom interacting with quantized electromagnetic field.
In the tree approximation, the $2s\to 1s +\gamma$ transition for hydrogen is
zero in the commutative case. As an example, we show that it is zero in the
same approximation for $\theta_{0i}\ne 0$. The importance of the deformed
rotational symmetry is commented upon further using the decay $Z^0 \to 2\gamma$
as an example.Comment: 13 pages, revised version, references adde

### Measurements in Gauge Mediated SUSY Breaking Models at LHC

Characteristic examples are presented of scenarios of particle production and
decay in supersymmetry models in which the supersymmetry breaking is
transmitted to the observable world via gauge interactions. The cases are
chosen to illustrate the main classes of LHC phenomenology that can arise in
these models. A new technique is illustrated that allows the full
reconstruction of supersymmetry events despite the presence of two unobserved
particles. This technique enables superparticle masses to be measured directly
rather than being inferred from kinematic distributions. It is demonstrated
that the LHC is capable of making sufficient measurements so as to severely
over-constrain the model and determine the parameters with great precisionComment: 45 pages, 35 Figure

### Lepton Flavor Violation at the LHC

Recent results from Super Kamiokande suggest $\nu_\mu-\nu_\tau$ mixing and
hence lepton flavor violation. In supersymmetric models, this flavor violation
may have implications for the pattern of slepton masses and mixings. Possible
signals for this mixing in the decays of sleptons produced at the LHC are
discussed. The sensitivity expected is compared to that of rare decays such as
$\tau\to \mu\gamma$.Comment: 14 pages, 9 figure

### Measurements in SUGRA Models with Large tan beta at LHC

We present an example of a scenario of particle production and decay in
supersymmetry models in which the supersymmetry breaking is transmitted to the
observable world via gravitational interactions. The case is chosen so that
there is a large production of tau leptons in the final state. It is
characteristic of large tan beta in that decays into muons and electrons may be
suppressed. It is shown that hadronic tau decays can be used to reconstruct
final states.Comment: 15 pages, 12 figure

### Universality in the Electroproduction of Vector Mesons

We study universality in the electroproduction of vector mesons using a
unified nonperturbative approach which has already proved to reproduce
extremely well the available experimental data. In this framework, after the
extraction of factors that are specific of each vector meson, we arrive at a
reduced integrated elastic cross section which is universal. Our calculations
suggest a finite infrared behavior for the strong coupling constant.Comment: 22 pages, 10 figure

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