arXiv subjects
Publications and source records attributed to Maria Krawczyk.
We consider a Z_2-symmetric Two Higgs Doublet Model (2HDM), where the vacuum expectation values of both doublets are non-vanishing. Unitarity constraints for the SM-like 2HDM are analyzed for the mass of the lightest Higgs boson in the range [115,127] GeV. New stringent bounds on tanβ, 0.17<tanβ<6.10, are derived. A discussion of the source of these constraints is provided.
Inert Doublet Model (IDM) is a minimal extension of the Standard Model with the second scalar doublet that may provide a Dark Matter candidate. In this paper we consider the different variants of the evolution of the Universe after inflation, that lead towards the Inert phase today.
The Dark 2HDM (called also the Inert Doublet Model) is the version of the Two-Higgs-Doublet Model with an exact $Z_2$ symmetry. It contains the SM-like Higgs boson $h$ and dark scalars $H$,$H^+,H^-$,$A$. Only dark scalars have odd $Z_2$ parity and therefore the lightest of them can be a dark matter candidate. The comparison of such model and of the standard 2HDM with an explicit $Z_2$ symmetry is given.
The most general Two Higgs Doublet Model (2HDM) allows both for the explicit and the spontaneous CP violation in the scalar sector. Here we discuss CP violation in terms of basis-independent quantities and show how using two different sets of known CP-odd weak-basis invariants one can distinguish between CP conservation, explicit CP violation and spontaneous CP violation. The special case of CP violation without CP mixing, in which the neutral Higgs gauge boson interaction respects CP while Higgs self-interaction violates CP symmetry, is also presented.
The introductory remarks to the conference Photon 2007 organized at the Sorbonne in Paris in July 2007 are presented.
Mass range of the charged Higgs boson in the 2HDM with explicit and spontaneous CP violation is discussed. Constraints on M_H+ in the CP conserving 2HDM(II) are shown.
Properties of the Higgs sector of Two Higgs Doublet Model (2HDM) and existing constraints on its parameters are discussed. Potential of the Photon Linear Collider in testing various Higgs scenarios of 2HDM, including the MSSM, based on the realistic simulations is also presented.
We use the invariance of physical picture under a change of Lagrangian, the reparametrization invariance in the space of Lagrangians and its particular case -- the rephrasing invariance, for analysis of the two-Higgs-doublet extension of the SM. We found that some parameters of theory like tan beta are reparametrization dependent and therefore cannot be fundamental. We use the Z2-symmetry of the Lagrangian, which prevents a phi_1 <-> phi_2 transitions, and the different levels of its violation, soft and hard, to describe a physical content of the model. In general, the broken Z2-symmetry allows for a CP violation in the physical Higgs sector. We argue that the 2HDM with a soft breaking of Z2-symmetry is a natural model in the description of EWSB. To simplify an analysis we choose among different forms of Lagrangian describing the same physical reality a specific one, in which the vacuum expectation values of both Higgs fields are real. A possible CP violation in the Higgs sector is described by using a two-step procedure with the first step identical to a diagonalization of mass matrix for CP-even fields in the CP conserved case. We find very simple necessary and sufficient condition for a CP violation in the Higgs sector. We determine the range of parameters for which CP violation and Flavor Changing Neutral Current effects are naturally small,what corresponds to a small dimensionless mass parameter nu= Re m_{12}^2/(2v1v2). We discuss how for small nu some Higgs bosons can be heavy, with mass up to about 0.6 TeV, without violating of the unitarity constraints. We discuss main features of the large nu case, which corresponds for nu -> infty to a decoupling of heavy Higgs bosons.
A short overview of basics aspects of hadronic interaction of the photon is presented.
Recent results obtained within ECFA/DESY and ECFA Study by the Higgs and gamma gamma /e gamma physics working groups are presented.
The next-to-leading order (NLO) QCD calculation for the isolated photon and isolated photon plus jet photoproduction at the ep collider DESY HERA is presented. The predictions for the isolated photon with no restrictions imposed on the jet are compared with the previous ones obtained in the small cone approximation, and the differences are found to be below 2%. The theoretical uncertainties in the cross section of the photoproduction of the photon plus jet are discussed. A short comparison with the new preliminary H1 data and with the NLO predictions of Fontannaz et al. is also presented.
A (updated) summary of the Photon-Photon and Electron-Photon physics session is presented.
We consider the Two-Higgs-Doublet Model and determine the range of parameters for which CP violation and Flavor Changing Neutral Current effects are naturally small. It corresponds to small values of the mass parameter m_{12}^2, describing soft (ϕ_1,ϕ_2) mixing in the potential. We discuss how, in this approach, some Higgs bosons can be heavy, with mass of the order of 1 TeV. The possibility that at the Tevatron, LHC and an e^+e^- Linear Collider, only one Higgs boson will be found, with properties indistinguishable from those in the Standard Model (SM), we define as the SM-like scenario. While this scenario can be obtained with large μ^2 \sim \Re m_{12}^2 parameter, in which case there is decoupling, we here discuss the opposite case of small μ^2, without decoupling.
The importance of the contributions of the longitudinally polarized virtual photon in ep collisions is investigated. We derive the factorization formulae for the unpolarized inclusive and semi-inclusive ep collisions in an arbitrary reference frame. The numerical calculations for the prompt photons production in the unpolarized Compton process (e p --> e gamma X) at the ep HERA collider are performed in the Born approximation. We studied various distributions in the ep centre-of-mass frame and found that the differential cross section for the longitudinally polarized intermediate photon and the term due to the interference between the longitudinal- and transverse- polarization states of the photon are small, i.e. below 10% of the cross section. Moreover, these two contributions almost cancel one another, leading to a stronger domination of the transversely polarized virtual photon, even for its large virtuality. Relevance of the resolved longitudinal photon in a jet production in DIS events at HERA is commented. A relatively large (about 30%) effect due to the longitudinal-transverse interference term was found in the azimuthal-angle distribution in the Breit frame.
We discuss the implications of the recent evaluations of the SM contribution to a_mu=(g-2)_mu/2 in the light of the latest E821 measurement, which indicate \~ 3 sigma deviation. We derive the 95 % CL interval, delta a_mu, to be used to constrain any additional contribution to a_mu, beyond the SM ones; it has to have a positive sign. We apply the delta a_mu to constrain the light Higgs-boson scenarios in a Two-Higgs-Doublet-Model (``Model II''). If the constraints from the new (g-2)_mu results are combined with the other existing constraints, one can exclude a light-scalar scenario at 95 % CL, while a light-pseudoscalar scenario can be realized, for a pseudoscalar mass between 25 and 70 GeV, with tan beta in the range 25 < tan beta < 115.
This article summarizes the experimental and theoretical results presented and discussed at the International Conference on the Structure and Interactions of the Photon, PHOTON 2001, in Ascona.
The present limits on the lightest Higgs boson in 2HDM (II) in light of the new E821 measurement of g-2 for the muon are discussed.
The NLO QCD calculation for the photoproduction of the isolated photon with a large $p_T$ at the HERA $ep$ collider is presented. The single resolved photon contribution and the QCD corrections of order $α_s$ to the Born term are consistently included. The sizeable NNLO contributions, the box and the double resolved photon subprocesses, are taken into account in addition. The importance of the isolation cut, as well as the influence of other experimental cuts on the p_T and rapidity eta_gamma distributions are discussed in detail. Results are compared with experimental data and with the different NLO calculations.