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P. Osland

Publications and source records attributed to P. Osland.

At least 91 records · Page 5Linked to original sources
arXiv2004

Center-Edge Asymmetry at Hadron Colliders

We investigate the possibility of using the center-edge asymmetry to distinguish graviton exchange from other new physics effects at hadron colliders. Specifically, we study lepton-pair production within the ADD and RS scenarios. At the Tevatron, the graviton-Z interference is the most important contribution to the center-edge asymmetry, whereas at the LHC, the dominant contribution comes from gluon fusion via graviton exchange, which has no analogue at e^+ e^- colliders. We find that spin-2 and spin-1 exchange can be distinguished up to an ADD cut-off scale, M_H, of about 5 TeV, at the 95% CL. In the RS scenario, spin-2 resonances can be identified in most of the favored parameter space.

hep-ph↗
arXiv2003

Discriminating graviton exchange effects from other new physics scenarios in e^+e^- collisions

We study the possibility of uniquely identifying the effects of graviton exchange from other new physics in high energy e^+e^- annihilation into fermion-pairs. For this purpose, we use as basic observable a specific asymmetry among integrated differential distributions, that seems particularly suitable to directly test for such gravitational effects in the data analysis.

hep-ph↗
arXiv2003

Model-independent constraints on contact interactions from LEP2 data analysis

We derive model-independent constraints on four-fermion contact interaction-type dynamics from the published preliminary LEP2 experimental data on e^+e^- annihilation into μ^+μ^- and τ^+τ^- pairs, measured at different energies between 130 and 207 GeV. The basic observables are chosen to be the total cross section and the forward-backward asymmetry, and the analysis realistically takes into account data uncertainties and correlations among measurements at the various energies. The combination of data from different energy points plays an important role in the determination of regions allowed for the contact interaction coupling constants. In contrast to the more common one-parameter analyses, we only obtain constraints on pairs of parameters rather than limits on individual ones.

hep-ph↗
arXiv2001

New physics signatures at a Linear Collider: model-independent analysis from `conventional' polarized observables

We discuss four-fermion contact-interaction searches in the processes e^+e^-\toμ^+μ^-, c{\bar c} and b{\bar b} at a future e^+e^- Linear Collider with c.m. energy \sqrt{s}=0.5 TeV and with both beams longitudinally polarized. Our analysis is based on the measurements of familiar polarized observables such as the total cross section and the forward-backward/left-right asymmetries, and accounts for the general set of contact interaction couplings as independent, non-zero, parameters thus avoiding simplifying, model-dependent, assumptions. We derive the corresponding model-independent constraints on the above-mentioned coupling constants, and evaluate the corresponding reach at the Linear Collider, emphasizing the role of beam polarization. We compare the results with a model-dependent procedure where only one coupling is varied at a time.

hep-ph↗
arXiv2001

Quark mass dependence of the one-loop three-gluon vertex in arbitrary dimension

The one-loop off-shell massive quark contribution to the three-gluon vertex is calculated in an arbitrary space-time dimension. The results for all relevant on-shell and symmetric limits are obtained directly from the general off-shell results. The analytic structure of the results for the relevant massive scalar integrals is also discussed.

hep-ph↗
arXiv2001

Contact interactions and polarized beams at a Linear Collider

We discuss contact-interaction searches in the processes e^+e^-\to μ^+μ^-, b\bar{b} and c\bar{c} at an e^+e^- Linear Collider with c.m. energy \sqrt{s}=0.5 TeV and with longitudinally polarized beams. The measurement of polarized cross sections allows to study the individual helicity cross sections, and consequently to derive separate, model-independent, constraints on the four-fermion contact interaction couplings. We evaluate the reach on those parameters foreseeable in the case of both electron and positron polarization fixed at some reference values, and compare it with the situation where only electron polarization is available. The analysis is based on polarized integrated cross sections with optimal kinematical cuts that can improve the sensitivity to the relevant couplings. While electron polarization would by itself allow such an analysis, the additional positron polarization (with no loss of beam intensity) and optimization can have a crucial role in improving the sensitivity to the new interactions.

hep-ph↗
arXiv2000

One-loop results for the quark-gluon vertex in arbitrary dimension

Results on the one-loop quark-gluon vertex with massive quarks are reviewed, in an arbitrary covariant gauge and in arbitrary space-time dimension. We show how it is possible to get on-shell results from the general off-shell expressions. The corresponding Ward-Slavnov-Taylor identity is discussed.

hep-ph↗
arXiv2000

Quark-gluon vertex in arbitrary gauge and dimension

One-loop off-shell contributions to the quark-gluon vertex are calculated, in an arbitrary covariant gauge and in arbitrary space-time dimension, including quark-mass effects. It is shown how one can get results for all on-shell limits of interest directly from the off-shell expressions. In order to demonstrate that the Ward-Slavnov-Taylor identity for the quark-gluon vertex is satisfied, we have also calculated the corresponding one-loop contribution involving the quark-quark-ghost-ghost vertex.

hep-ph↗
arXiv2000

Contact interaction probes at the Linear Collider with polarized electron and positron beams

For contact-interaction searches at the Linear Collider, we discuss the advantages of polarizing both the electron and the positron beams as compared with polarizing only the electron beam. In particular, for the processes e^+e^-\to μ^+μ^-, τ^+τ^-, b\bar{b} and c\bar{c} at a future e^+e^- collider with \sqrt{s}=0.5 TeV we derive model-independent bounds on the four-fermion contact interaction parameters from studies of the helicity cross sections.

hep-ph↗
arXiv2000

Optimal polarized observables for model-independent new-physics search at e+e- colliders

For the processes e+e-\to μ+μ-, τ+τ-, b\bar{b} and c\bar{c} at a future e+e- collider with \sqrt{s}=0.5 TeV, we examine the sensitivity of the helicity cross sections to four-fermion contact interactions. If longitudinal polarization of the electron beam were available, two polarized integrated cross sections would offer the opportunity to separate the helicity cross sections and, in this way, to derive model-independent bounds on the relevant parameters. The measurement of these polarized cross sections with optimal kinematical cuts could significantly increase the sensitivity of helicity cross sections to contact interaction parameters and could give crucial information on the chiral structure of such new interactions.

hep-ph↗
arXiv1999

Multiple Higgs Production and Measurement of Higgs Trilinear Couplings in the MSSM

An elementary Higgs boson, which is the remnant of the spontaneous symmetry breaking mechanism in the Standard Model, remains one of the most elusive particles. If a Higgs boson candidate is found at future accelerators, it becomes necessary to determine its properties, beyond the mass, production cross section and decay rates. The other crucial properties relate to the self-couplings of the Higgs boson, which are necessary to reconstruct the Higgs potential, and thereby confirm the mechanism of spontaneous symmetry breaking. In this paper we review the question of the measurability of some of the trilinear couplings of the neutral Higgs bosons of the Minimal Supersymmetric Standard Model at a high-energy e+e- collider.

hep-ph↗
arXiv1999

Higgs boson production in e^+e^- and e^-e^- collisions

When Higgs boson candidates will be found at future colliders, it becomes imperative to determine their properties, beyond the mass, production cross section and decay rates. Other crucial properties are those related to the behaviour under CP transformations, and the self-couplings. This paper addresses the question of measurability of some of the trilinear couplings of MSSM neutral Higgs bosons at a high-energy e^+e^- collider, and the possibilities of exploring the Higgs boson CP properties at e^+e^- and e^-e^- colliders.

hep-ph↗
arXiv1999

Measuring Trilinear Higgs Couplings in the MSSM

Trilinear couplings of the neutral CP-even Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM) can be measured through the multiple production of the lightest CP-even Higgs boson (h) at high-energy e^+e^- colliders. This includes the production of the heavier CP-even Higgs boson (H) via e^+e^- \to ZH, in association with the CP-odd Higgs boson (A) in e^+e^- \to AH, or via e^+e^- \to ν_e \barν_e H, with H subsequently decaying through H \to hh. These processes can enable one to measure the trilinear Higgs couplings λ_{Hhh} and λ_{hhh}, which can be used to theoretically reconstruct the Higgs potential. We delineate the regions of the MSSM parameter space in which these trilinear Higgs couplings could be measured.

hep-ph↗
arXiv1998

Measuring the Trilinear Couplings of MSSM Neutral Higgs Bosons at High-Energy e^+e^- Colliders

We present a detailed analysis of multiple production of the lightest CP-even Higgs boson (h) of the Minimal Supersymmetric Standard Model (MSSM) at high-energy e^+ e^- colliders. We consider the production of the heavier CP-even Higgs boson (H) via Higgs-strahlung e^+e^- \to ZH, in association with the CP-odd Higgs boson (A) in e^+e^- \to AH, or via the fusion mechanism e^+e^- \to ν_e \barν_e H, with H subsequently decaying through H \to hh, thereby resulting in a pair of lighter Higgs bosons (h) in the final state. These processes can enable one to measure the trilinear Higgs couplings λ_{Hhh} and λ_{hhh}, which can be used to theoretically reconstruct the Higgs potential. We delineate the regions of the MSSM parameter space in which these trilinear Higgs couplings could be measured at a future e^+ e^- collider. In our calculations, we include in detail the radiative corrections to the Higgs sector of the MSSM, especially the mixing in the squark sector.

hep-ph↗
arXiv1998

Higgs Production: CP Studies in e-e- Collisions

We review the production of scalar Higgs-like particles in high-energy electron-electron collisions, via the fusion of electroweak gauge bosons. The emphasis is on how to distinguish a CP-even from a CP-odd Higgs particle. Among the more significant differences, we find that in the CP-odd case, the Higgs spectrum is much harder, and the dependence of the total cross section on the product of the polarizations of the two beams is much stronger, than in the CP-even case. We also briefly discuss parity violation, and the production of charged Higgs bosons.

hep-ph↗
arXiv1998

On-shell two-loop three-gluon vertex

The two-loop three-gluon vertex is calculated in an arbitrary covariant gauge, in the limit when two of the gluons are on the mass shell. The corresponding two-loop results for the ghost-gluon vertex are also obtained. It is shown that the results are consistent with the Ward-Slavnov-Taylor identities.

hep-ph↗
arXiv1998

Solar-neutrino oscillations and third-flavour admixture

With one Δm^2 of the appropriate order of magnitude to solve the atmospheric neutrino problem, we study the resulting three-generation vacuum-oscillation fit to the solar neutrino flux. An explanation of the atmospheric neutrino composition in terms of pure ν_μ\to ν_τoscillations is easily compatible with the well-known two-flavour oscillation solution for solar neutrinos. The allowed parameter region in the \sin^2(2θ_{12})--Δm^2 plane changes little with increasing values of the mixing element U_{e3}, provided this is less than about 0.4. We find that the threefold maximal mixing is disfavoured.

hep-ph↗