2,130 research outputs found
Nonresonant searches for axion-like particles in vector boson scattering processes at the LHC
We propose a new search for Axion-Like Particles (ALPs), targeting Vector
Boson Scattering (VBS) processes at the LHC. We consider nonresonant ALP-mediated
VBS, where the ALP participates as an off-shell mediator. This process occurs whenever
the ALP is too light to be produced resonantly, and it takes advantage of the derivative
nature of ALP interactions with the electroweak Standard Model bosons. We study the
production of ZZ, Zγ, W ±γ, W ±Z and W ±W ± pairs with large diboson invariant masses
in association with two jets. Working in a gauge-invariant framework, upper limits on
ALP couplings to electroweak bosons are obtained from a reinterpretation of Run 2 public
CMS VBS analyses. The constraints inferred on ALP couplings to ZZ, Zγ and W ±W ±
pairs are very competitive for ALP masses up to 100 GeV. They have the advantage of
being independent of the ALP coupling to gluons and of the ALP decay width. Simple
projections for LHC Run 3 and HL-LHC are also calculated, demonstrating the power of
future dedicated analyses at ATLAS and CMS
PDB44 THE COST-EFFECTIVENESS OF SAXAGLIPTIN VERSUS SULFONYLUREA (SU) IN THE TREATMENT OF TYPE 2 DIABETES MELLITUS (T2DM) IN GERMANY
Vector form factor of the pion : A model-independent approach
We study a model-independent parameterization of the vector pion form factor
that arises from the constraints of analyticity and unitarity. Our description
should be suitable up to s^(1/2) ~ 1.2 GeV and allows a model-independent
determination of the mass of the rho(770) resonance. We analyse the
experimental data on tau^- -> pion^- pion^0 nu_tau and e^+ e^- -> pion^+ pion^-
in this framework, and its consequences on the low-energy observables worked
out by chiral perturbation theory. An evaluation of the two pion contribution
to the anomalous magnetic moment of the muon, a_{mu}, and to the fine structure
constant, alpha(M_Z^2), is also performed.Comment: 5 pages, 2 figures. To appear in the proceedings of the High-Energy
Physics International Conference on Quantum Chromodynamics QCD02, Montpellier
(France), 2-9 July (2002
New results on the hadronic vacuum polarization to the muon g-2
Results on the lowest-order hadronic vacuum polarization contribution to the
muon magnetic anomaly are presented. They are based on the latest published
experimental data used as input to the dispersion integral. Thus recent results
on tau to nutau pi pi0 decays from Belle and on e+ e- annihilation to pi+ pi-
from BABAR and KLOE are included. The new data, together with improved
isospin-breaking corrections for tau decays, result into a much better
consistency among the different results. A discrepancy between the Standard
Model prediction and the direct g-2 measurement is found at the level of 3
sigma.Comment: proceedings of the PhiPsi09 conference, Oct. 13-16, 2009, Beijing,
Chin
Contribution to muon g-2 from the \pi0\gamma and \eta\gamma intermediate states in the vacuum polarization
Using new experimental data, we have calculated the contribution to the
anomalous magnetic moment of the muon from the \pi0\gamma and \eta\gamma
intermediate states in the vacuum polarization with high precision:
a{\mu}(\pi0\gamma)+a{\mu}(\eta\gamma)=(54.7\pm 1.5)\times 10^{-11}. We have
also found the small contribution from e+e-\pi0, e+e-\eta and \mu+\mu-\pi0
intermediate states equal to 0.5\times 10^{-11}.Comment: 6 pages, 2 figures, revte
On the precision of the theoretical predictions for pi pi scattering
In a recent paper, Pelaez and Yndurain evaluate some of the low energy
observables of pi pi scattering and obtain flat disagreement with our earlier
results. The authors work with unsubtracted dispersion relations, so that their
results are very sensitive to the poorly known high energy behaviour of the
scattering amplitude. They claim that the asymptotic representation we used is
incorrect and propose an alternative one. We repeat their calculations on the
basis of the standard, subtracted fixed-t dispersion relations, using their
asymptotics. The outcome fully confirms our earlier findings. Moreover, we show
that the Regge parametrization proposed by these authors for the region above
1.4 GeV violates crossing symmetry: Their ansatz is not consistent with the
behaviour observed at low energies.Comment: Added more material, mostly in Sects. 7, 8 and 9, in support of the
same conclusions. Latex, 28 pages, 3 figure
Neutralino Dark Matter in Mirage Mediation
We study the phenomenology of neutralino dark matter (DM) in mirage mediation
scenario of supersymmetry breaking which results from the moduli stabilization
in some string/brane models. Depending upon the model parameters, especially
the anomaly to modulus mediation ratio determined by the moduli stabilization
mechanism, the nature of the lightest supersymmetric particle (LSP) changes
from Bino-like neutralino to Higgsino-like one via Bino-Higgsino mixing region.
For the Bino-like LSP, the standard thermal production mechanism can give a
right amount of relic DM density through the stop/stau-neutralino
coannihilation or the pseudo-scalar Higgs resonance process. We also examine
the prospect of direct and indirect DM detection in various parameter regions
of mirage mediation. Neutralino DM in galactic halo might be detected by near
future direct detection experiments in the case of Bino-Higgsino mixed LSP. The
gamma ray flux from Galactic Center might be detectable also if the DM density
profile takes a cuspy shape.Comment: One reference adde
Constraining Supersymmetry
We review constraints on the minimal supersymmetric extension of the Standard
Model (MSSM) coming from direct searches at accelerators such as LEP, indirect
measurements such as b -> s gamma decay and the anomalous magnetic moment of
the muon. The recently corrected sign of pole light-by-light scattering
contributions to the latter is taken into account. We combine these constraints
with those due to the cosmological density of stable supersymmetric relic
particles. The possible indications on the supersymmetric mass scale provided
by fine-tuning arguments are reviewed critically. We discuss briefly the
prospects for future accelerator searches for supersymmetry.Comment: 21 LaTeX pages, 9 eps figures, Invited Contribution to the New
Journal of Physics Focus Issue on Supersymmetr
Adiabatic compression and indirect detection of supersymmetric dark matter
Recent developments in the modelling of the dark matter distribution in our
Galaxy point out the necessity to consider some physical processes to satisfy
observational data. In particular, models with adiabatic compression, which
include the effect of the baryonic gas in the halo, increase significantly the
dark matter density in the central region of the Milky Way. On the other hand,
the non-universality in scalar and gaugino sectors of supergravity models can
also increase significantly the neutralino annihilation cross section. We show
that the combination of both effects gives rise to a gamma-ray flux arising
from the Galactic Center largely reachable by future experiments like GLAST. We
also analyse in this framework the EGRET excess data above 1 GeV, as well as
the recent data from CANGAROO and HESS. The analysis has been carried out
imposing the most recent experimental constraints, such as the lower bound on
the Higgs mass, the \bsg branching ratio, and the muon . In addition, the
recently improved upper bound on has also been taken
into account. The astrophysical (WMAP) bounds on the dark matter density have
also been imposed on the theoretical computation of the relic neutralino
density through thermal production.Comment: 32 pages, 11 figures, final version to appear in JCA
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