183 research outputs found
Nagy-Soper subtraction scheme for multiparton final states
In this work, we present the extension of an alternative subtraction scheme
for next-to-leading order QCD calculations to the case of an arbitrary number
of massless final-state partons. The scheme is based on the splitting kernels
of an improved parton shower and comes with a reduced number of final state
momentum mappings. While a previous publication including the setup of the
scheme has been restricted to cases with maximally two massless partons in the
final state, we here provide the final state real emission and integrated
subtraction terms for processes with any number of massless partons. We apply
our scheme to three jet production at lepton colliders at next-to-leading order
and present results for the differential C parameter distribution.Comment: 45 pages, 5 figures v2: several references added; v3: title changed,
references and a discussion of further scaling improvement added. Corresponds
to published journal versio
Les Houches 2011: Physics at TeV Colliders New Physics Working Group Report
We present the activities of the "New Physics" working group for the "Physics
at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our
report includes new agreements on formats for interfaces between computational
tools, new tool developments, important signatures for searches at the LHC,
recommendations for presentation of LHC search results, as well as additional
phenomenological studies.Comment: 243 pages, report of the Les Houches 2011 New Physics Group; fix
three figure
JUNO Conceptual Design Report
The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine
the neutrino mass hierarchy using an underground liquid scintillator detector.
It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants
in Guangdong, China. The experimental hall, spanning more than 50 meters, is
under a granite mountain of over 700 m overburden. Within six years of running,
the detection of reactor antineutrinos can resolve the neutrino mass hierarchy
at a confidence level of 3-4, and determine neutrino oscillation
parameters , , and to
an accuracy of better than 1%. The JUNO detector can be also used to study
terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard
Model. The central detector contains 20,000 tons liquid scintillator with an
acrylic sphere of 35 m in diameter. 17,000 508-mm diameter PMTs with high
quantum efficiency provide 75% optical coverage. The current choice of
the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO
as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of
detected photoelectrons per MeV is larger than 1,100 and the energy resolution
is expected to be 3% at 1 MeV. The calibration system is designed to deploy
multiple sources to cover the entire energy range of reactor antineutrinos, and
to achieve a full-volume position coverage inside the detector. The veto system
is used for muon detection, muon induced background study and reduction. It
consists of a Water Cherenkov detector and a Top Tracker system. The readout
system, the detector control system and the offline system insure efficient and
stable data acquisition and processing.Comment: 328 pages, 211 figure
Interpreting a 750 GeV diphoton resonance
We discuss the implications of the significant excesses in the diphoton final
state observed by the LHC experiments ATLAS and CMS around a diphoton invariant
mass of 750 GeV. The interpretation of the excess as a spin-zero s-channel resonance implies
model-independent lower bounds on both its branching ratio and its coupling to photons,
which stringently constrain dynamical models. We consider both the case where the
excess is described by a narrow and a broad resonance. We also obtain model-independent
constraints on the allowed couplings and branching fractions to final states other than
diphotons, by including the interplay with 8 TeV searches. These results can guide attempts
to construct viable dynamical models of the resonance. Turning to specific models,
our findings suggest that the anomaly cannot be accounted for by the presence of only an
additional singlet or doublet spin-zero field and the Standard Model degrees of freedom; this
includes all two-Higgs-doublet models. Likewise, heavy scalars in the MSSM cannot explain
the excess if stability of the electroweak vacuum is required, at least in a leading-order analysis.
If we assume that the resonance is broad we find that it is challenging to find a weakly
coupled explanation. However, we provide an existence proof in the form of a model with
vectorlike quarks with large electric charge that is perturbative up to the 100 TeV scale.
For the narrow-resonance case a similar model can be perturbative up to high scales also
with smaller charges. We also find that, in their simplest form, dilaton models cannot
explain the size of the excess. Some implications for flavor physics are briefly discussed
Higgs Working Group Report of the Snowmass 2013 Community Planning Study
This report summarizes the work of the Energy Frontier Higgs Boson working
group of the 2013 Community Summer Study (Snowmass). We identify the key
elements of a precision Higgs physics program and document the physics
potential of future experimental facilities as elucidated during the Snowmass
study. We study Higgs couplings to gauge boson and fermion pairs, double Higgs
production for the Higgs self-coupling, its quantum numbers and -mixing in
Higgs couplings, the Higgs mass and total width, and prospects for direct
searches for additional Higgs bosons in extensions of the Standard Model. Our
report includes projections of measurement capabilities from detailed studies
of the Compact Linear Collider (CLIC), a Gamma-Gamma Collider, the
International Linear Collider (ILC), the Large Hadron Collider High-Luminosity
Upgrade (HL-LHC), Very Large Hadron Colliders up to 100 TeV (VLHC), a Muon
Collider, and a Triple-Large Electron Positron Collider (TLEP)
The physics case of a 3 TeV muon collider stage
In the path towards a muon collider with center of mass energy of 10 TeV ormore, a stage at 3 TeV emerges as an appealing option. Reviewing the physicspotential of such muon collider is the main purpose of this document. In orderto outline the progression of the physics performances across the stages, a fewsensitivity projections for higher energy are also presented. There are manyopportunities for probing new physics at a 3 TeV muon collider. Some of themare in common with the extensively documented physics case of the CLIC 3 TeVenergy stage, and include measuring the Higgs trilinear coupling and testingthe possible composite nature of the Higgs boson and of the top quark at the 20TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stemfrom the fact that muons are collided rather than electrons. This isexemplified by studying the potential to explore the microscopic origin of thecurrent -2 and -physics anomalies, which are both related with muons.<br
The physics case of a 3 TeV muon collider stage
In the path towards a muon collider with center of mass energy of 10 TeV ormore, a stage at 3 TeV emerges as an appealing option. Reviewing the physicspotential of such muon collider is the main purpose of this document. In orderto outline the progression of the physics performances across the stages, a fewsensitivity projections for higher energy are also presented. There are manyopportunities for probing new physics at a 3 TeV muon collider. Some of themare in common with the extensively documented physics case of the CLIC 3 TeVenergy stage, and include measuring the Higgs trilinear coupling and testingthe possible composite nature of the Higgs boson and of the top quark at the 20TeV scale. Other opportunities are unique of a 3 TeV muon collider, and stemfrom the fact that muons are collided rather than electrons. This isexemplified by studying the potential to explore the microscopic origin of thecurrent -2 and -physics anomalies, which are both related with muons.<br
The CLIC Potential for New Physics
The Compact Linear Collider (CLIC) is a mature option for the future of high
energy physics. It combines the benefits of the clean environment of
colliders with operation at high centre-of-mass energies, allowing to probe
scales beyond the reach of the Large Hadron Collider (LHC) for many scenarios of new physics. This places the CLIC project at a privileged spot in between the precision and energy frontiers, with capabilities that will significantly extend knowledge on both fronts at the end of the LHC era. In this report we review and revisit the potential of CLIC to search, directly and indirectly, for physics beyond the Standard Model
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