3,672 research outputs found
AWAKE, The Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN
The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) aims at studying plasma wakefield generation and electron acceleration driven by proton bunches. It is a proof-of-principle R&D experiment at CERN and the world׳s first proton driven plasma wakefield acceleration experiment. The AWAKE experiment will be installed in the former CNGS facility and uses the 400 GeV/c proton beam bunches from the SPS. The first experiments will focus on the self-modulation instability of the long (rms ~12 cm) proton bunch in the plasma. These experiments are planned for the end of 2016. Later, in 2017/2018, low energy (~15 MeV) electrons will be externally injected into the sample wakefields and be accelerated beyond 1 GeV. The main goals of the experiment will be summarized. A summary of the AWAKE design and construction status will be presented
Next-to-leading order predictions for WW + 1 jet distributions at the LHC
We present numerical results for the production of a pair in
association with a jet at the LHC in QCD at next-to-leading order (NLO). We
include effects of the decay of the massive vector bosons into leptons with
spin correlations and contributions from the third generation of massive
quarks. The calculation is performed using a semi-numerical method for the
virtual corrections, and is implemented in MCFM. In addition to its importance
{\it per se} as a test of the Standard Model, this process is an important
background to searches for the Higgs boson and to many new physics searches. As
an example, we study the impact of NLO corrections to jet production
on the search for a Higgs boson at the LHC.Comment: 21 pages, 9 figures; v3 published versio
Searching for the Kaluza-Klein Graviton in Bulk RS Models
The best-studied version of the RS1 model has all the Standard Model
particles confined to the TeV brane. However, recent variants have the Standard
Model fermions and gauge bosons located in the bulk five-dimensional spacetime.
We study the potential reach of the LHC in searching for the lightest KK
partner of the graviton in the most promising such models in which the
right-handed top is localized very near the TeV brane and the light fermions
are localized near the Planck brane. We consider both detection and the
establishment of the spin-2 nature of the resonance should it be found.Comment: 17 pages, 6 figures - JHEP published version, figures added,
branching ratio correcte
Physics at the LHC: a short overview
The CERN Large Hadron Collider (LHC) started operation a few months ago. The
machine will deliver proton-proton and nucleus-nucleus collisions at energies
as high as sqrt(s)=14 TeV and luminosities up to L~10^{34} cm^{-2}s^{-1}, never
reached before. The main open scientific questions that the seven LHC
experiments -- ATLAS, CMS, ALICE, LHCb, TOTEM, LHCf and MOEDAL -- aim to solve
in the coming years are succinctly reviewed.Comment: 9 pages, 16 plots. Invited review talk Hot-Quarks 2010, La
Londe-Les-Maures, July 2010. J. Phys. Conf. Ser. 270, 012001 (2011). Minor
typos correcte
Triviality and the (Supersymmetric) See-Saw
For the D=5 Majorana neutrino mass operator to have a see-saw ultraviolet
completion that is viable up to the Planck scale, the see-saw scale is bounded
above due to triviality limits on the see-saw couplings. For supersymmetric
see-saw models, with realistic neutrino mass textures, we compare constraints
on the see-saw scale from triviality bounds, with those arising from
experimental limits on induced charged-lepton flavour violation, for both the
CMSSM and for models with split supersymmetry.Comment: 27 pages, 7 figures, references adde
NLO predictions for t-channel production of single top and fourth generation quarks at hadron colliders
We present updated NLO predictions for the electroweak t-channel production
of heavy quarks at the Tevatron and at the LHC. We consider production of
single top and fourth generation t' starting from both 2 to 2 and 2 to 3 Born
processes. Predictions for tb' and t'b' cross sections at NLO are also given
for the first time. A thorough study of the theoretical uncertainties coming
from parton distribution functions, renormalisation and factorisation scale
dependence and heavy quark masses is performed.Comment: 25 pages, 8 figure
Little Higgs models and single top production at the LHC
We investigate the corrections of the littlest Higgs(LH) model and the SU(3)
simple group model to single top production at the CERN Large Hardon
Collider(LHC). We find that the new gauge bosons predicted by the
LH model can generate significant contributions to single top production via
the s-channel process. The correction terms for the tree-level couplings
coming from the SU(3) simple group model can give large contributions to the
cross sections of the t-channel single top production process. We expect that
the effects of the LH model and the SU(3) simple group model on single top
production can be detected at the LHC experiments.Comment: 17pages, 5 figures, discussions and references added, typos correcte
tt charge asymmetry, family and friends
We present the current status of the Tevatron charge asymmetry and its sister asymmetry at the LHC. The relation between both is elucidated, using as framework the collider-independent asymmetries they originate from. Other related observables, such as the t tbar differential distribution and top polarisation, are also discussed.This work has been supported by MICINN by projects FPA2006-05294 and FPA2010-17915,
Junta de Andalucía (FQM 101, FQM 03048 and FQM 6552) and Fundaçao para a Ciencia e
Tecnologia (FCT) project CERN/FP/123619/2011
Supersymmetry discovery potential of the LHC at 10 and 14 TeV without and with missing
We examine the supersymmetry (SUSY) reach of the CERN LHC operating at
and 14 TeV within the framework of the minimal supergravity
model. We improve upon previous reach projections by incorporating updated
background calculations including a variety of Standard Model (SM)
processes. We show that SUSY discovery is possible even before the detectors
are understood well enough to utilize either or electrons in
the signal. We evaluate the early SUSY reach of the LHC at TeV by
examining multi-muon plus jets and also dijet events with {\it no}
missing cuts and show that the greatest reach in terms of
occurs in the dijet channel. The reach in multi-muons is slightly smaller in
, but extends to higher values of . We find that an observable
multi-muon signal will first appear in the opposite-sign dimuon channel, but as
the integrated luminosity increases the relatively background-free but
rate-limited same-sign dimuon, and ultimately the trimuon channel yield the
highest reach. We show characteristic distributions in these channels that
serve to distinguish the signal from the SM background, and also help to
corroborate its SUSY origin. We then evaluate the LHC reach in various
no-lepton and multi-lepton plus jets channels {\it including} missing
cuts for and 14 TeV, and plot the reach for integrated
luminosities ranging up to 3000 fb at the SLHC. For TeV,
the LHC reach extends to and 2.9 TeV for
and integrated luminosities of 10, 100, 1000 and
3000 fb, respectively. For TeV, the LHC reach for the same
integrated luminosities is to m_{gluino}=2.4,\3.1, 3.7 and 4.0 TeV.Comment: 34 pages, 25 figures. Revised projections for the SUSY reach for
ab^-1 integrated luminosities, with minor corrections of references and text.
2 figures added. To appear in JHE
aMCfast: automation of fast NLO computations for PDF fits
We present the interface between MadGraph5 aMC@NLO, a self-contained program that calculates cross sections up to next-to-leading order accuracy in an automated manner, and APPLgrid, a code that parametrises such cross sections in the form of look-up tables which can be used for the fast computations needed in the context of PDF fits. The main characteristic of this interface, which we dub aMCfast, is its being fully automated as well, which removes the need to extract manually the process-specific information for additional physics processes, as is the case with other matrix-element calculators, and renders it straightforward to include any new process in the PDF fits. We demonstrate this by studying several cases which are easily measured at the LHC, have a good constraining power on PDFs, and some of which were previously unavailable in the form of a fast interface
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