13,734 research outputs found
Review of Linac-Ring Type Collider Proposals
There are three possibly types of particle colliders schemes: familiar (well
known) ring-ring colliders, less familiar however sufficiently advanced linear
colliders and less familiar and less advanced linac-ring type colliders. The
aim of this paper is two-fold: to present possibly complete list of papers on
linac-ring type collider proposals and to emphasize the role of linac-ring type
machines for future HEP research.Comment: quality of figures is improved, some misprints are correcte
The Heliosphere---Blowing in the Interstellar Wind
Measurements of the velocity of interstellar HeI inside of the heliosphere
have been conducted over the past forty years. These historical data suggest
that the ecliptic longitude of the direction of the interstellar flow has
increased at an average rate of about 0.19 degrees per year over time. Possible
astronomical explanations for these short-term variations in the interstellar
gas entering the heliosphere are presented.Comment: Accepted for the proceedings of Solar Wind 1
Signs of heavy Higgs bosons at CLIC: An road to the Electroweak Phase Transition
We analyse the sensitivity of the proposed Compact Linear Collider (CLIC) to
the existence of beyond the Standard Model (SM) Higgs bosons through their
decays into pairs of massive gauge bosons and SM-like Higgses , considering CLIC centre of mass energies TeV and TeV.
We find that resonant di-Higgs searches at CLIC would allow for up to two
orders of magnitude improvement w.r.t. the sensitivity achievable by HL-LHC in
the mass range . Focusing then
on a real singlet extension of the SM, we explore the prospects of heavy Higgs
searches at CLIC for probing the regions of parameter space yielding a strongly
first order electroweak phase transition that could generate the observed
matter-antimatter asymmetry of the Universe. Our study illustrates the
complementarity between CLIC and other possible future colliders like FCC-ee in
probing singlet extensions of the SM, and shows that high-energy
colliders provide a powerful means to unravel the nature of electroweak
symmetry breaking in the early Universe.Comment: 27 pages, 15 figure
Probe of anomalous quartic couplings in the photon-photon collisions
In this paper, we examine the potentials of the processes and at the CLIC with
and TeV to investigate anomalous quartic
couplings by two different CP-violating and CP-conserving effective
Lagrangians. We find confidence level limits on the anomalous coupling
parameters at the three CLIC energies and various integrated luminosities. The
best limits obtained from the process
on the anomalous ,
and couplings
defined by CP-conserving effective Lagrangians are GeV, and GeV, while coupling
determined by CP-violating effective Lagrangians is obtained as GeV. In addition, the best limits derived on
, and
and from the
process are obtained as
GeV, GeV, and GeV, respectively.Comment: 33 pages, 27 figures, 4 tables, version to appear in JHE
Spatial modeling of extreme snow depth
The spatial modeling of extreme snow is important for adequate risk
management in Alpine and high altitude countries. A natural approach to such
modeling is through the theory of max-stable processes, an infinite-dimensional
extension of multivariate extreme value theory. In this paper we describe the
application of such processes in modeling the spatial dependence of extreme
snow depth in Switzerland, based on data for the winters 1966--2008 at 101
stations. The models we propose rely on a climate transformation that allows us
to account for the presence of climate regions and for directional effects,
resulting from synoptic weather patterns. Estimation is performed through
pairwise likelihood inference and the models are compared using penalized
likelihood criteria. The max-stable models provide a much better fit to the
joint behavior of the extremes than do independence or full dependence models.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS464 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Physics at LHC
The prospects for physics at the LHC are discussed, starting with the
foretaste, preparation (and perhaps scoop) provided by the Tevatron, in
particular, and then continuing through the successive phases of LHC operation.
These include the start-up phase, the early physics runs, the possible search
for new physics in double diffraction, the continuation to nominal LHC running,
and the possible upgrade of the LHC luminosity. Emphasis is placed on the
prospects for Higgs physics and the search for supersymmetry. The progress and
discoveries of the LHC will set the time-scale and agenda for the major future
accelerator projects that will follow it.Comment: 21 pages, 12 figures, Concluding talk at the Physics at LHC
conference, Krakow, July 200
Constraining the Higgs self couplings at colliders
We study the sensitivity to the shape of the Higgs potential of single,
double, and triple Higgs production at future colliders. Physics
beyond the Standard Model is parameterised through the inclusion of
higher-dimensional operators
with , which allows a consistent treatment of independent deviations of
the cubic and quartic self couplings beyond the tree level. We calculate the
effects induced by a modified potential up to one loop in single and double
Higgs production and at the tree level in triple Higgs production, for both
boson associated and boson fusion production mechanisms. We consider two
different scenarios. First, the dimension six operator provides the dominant
contribution (as expected, for instance, in a linear
effective-field-theory(EFT)); we find in this case that the corresponding
Wilson coefficient can be determined at accuracy by just
combining accurate measurements of single Higgs cross sections at 240-250 GeV and double Higgs production in boson fusion at higher
energies. Second, both operators of dimension six and eight can give effects of
similar order, i.e., independent quartic self coupling deviations are present.
Constraints on Wilson coefficients can be best tested by combining measurements
from single, double and triple Higgs production. Given that the sensitivity of
single Higgs production to the dimension eight operator is presently unknown,
we consider double and triple Higgs production and show that combining their
information colliders at higher energies will provide first coarse constraints
on the corresponding Wilson coefficient.Comment: minor changes, version accepted for publication in JHE
Establishing the Isolated Standard Model
The goal of this article is to initiate a discussion on what it takes to
claim "there is no new physics at the weak scale," namely that the Standard
Model (SM) is "isolated." The lack of discovery of beyond the SM (BSM) physics
suggests that this may be the case. But to truly establish this statement
requires proving all "connected" BSM theories are false, which presents a
significant challenge. We propose a general approach to quantitatively assess
the current status and future prospects of establishing the isolated SM (ISM),
which we give a reasonable definition of. We consider broad elements of BSM
theories, and show many examples where current experimental results are not
sufficient to verify the ISM. In some cases, there is a clear roadmap for the
future experimental program, which we outline, while in other cases, further
efforts -- both theoretical and experimental -- are needed in order to robustly
claim the establishment of the ISM in the absence of new physics discoveries.Comment: 10 pages, 2 figures, 1 tabl
Summary of ICHEP 2004
Aspects of ICHEP 2004 are summarized from a theoretical point of view. QCD
works, new NNLO calculations are becoming available and new string
calculational tools are emerging, but no conclusions can yet be drawn about the
discovery of the quark-gluon plasma or pentaquarks. The small upward shift in
the experimental value of m_t raises somewhat the central value of the Higgs
mass extracted from a global electroweak fit, and the CKM model describes well
the data from the B factories. The Super-Kamiokande, KamLAND and K2K
experiments have evidence for oscillation dips in their neutrino data. Little
Higgs models are interesting alternatives to low-energy supersymmetry for
stabilizing the electroweak scale. Convincing experimental evidence for dark
matter particles is still lacking. The LHC is on its way, the technology choice
clarifies the roadmap for the ILC, and a multi-TeV CLIC would also have rich
physics agenda.Comment: 19 pages LaTeX, 12 eps figures, Summary of the International
Conference on High-Energy Physics, Beijing, China, August 200
Updated Post-WMAP Benchmarks for Supersymmetry
We update a previously-proposed set of supersymmetric benchmark scenarios,
taking into account the precise constraints on the cold dark matter density
obtained by combining WMAP and other cosmological data, as well as the LEP and
b -> s gamma constraints. We assume that R parity is conserved and work within
the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking scalar
and gaugino masses m_0 and m_1/2. In most cases, the relic density calculated
for the previous benchmarks may be brought within the WMAP range by reducing
slightly m_0, but in two cases more substantial changes in m_0 and m_1/2 are
made. Since the WMAP constraint reduces the effective dimensionality of the
CMSSM parameter space, one may study phenomenology along `WMAP lines' in the
(m_1/2, m_0) plane that have acceptable amounts of dark matter. We discuss the
production, decays and detectability of sparticles along these lines, at the
LHC and at linear e+ e- colliders in the sub- and multi-TeV ranges, stressing
the complementarity of hadron and lepton colliders, and with particular
emphasis on the neutralino sector. Finally, we preview the accuracy with which
one might be able to predict the density of supersymmetric cold dark matter
using collider measurements.Comment: 43 pages LaTeX, 13 eps figure
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