1,338 research outputs found
Spin Analysis of Supersymmetric Particles
The spin of supersymmetric particles can be determined at colliders
unambiguously. This is demonstrated for a characteristic set of non-colored
supersymmetric particles -- smuons, selectrons, and charginos/neutralinos. The
analysis is based on the threshold behavior of the excitation curves for pair
production in collisions, the angular distribution in the production
process and decay angular distributions. In the first step we present the
observables in the helicity formalism for the supersymmetric particles.
Subsequently we confront the results with corresponding analyses of
Kaluza-Klein particles in theories of universal extra space dimensions which
behave distinctly different from supersymmetric theories. It is shown in the
third step that a set of observables can be designed which signal the spin of
supersymmetric particles unambiguously without any model assumptions. Finally
in the fourth step it is demonstrated that the determination of the spin of
supersymmetric particles can be performed experimentally in practice at an
collider.Comment: 39 pages, 14 figure
Loop Corrections to the Neutral Higgs Boson Sector of the MSSM with Explicit CP Violation
We compute one-loop corrections to the mass matrix of the neutral Higgs
bosons of the Minimal Supersymmetric Standard Model with explicit CP violation.
We use the effective potential method, allowing for arbitrary splitting between
squark masses. We include terms O(g^2 h^2), where g and h stand for electroweak
gauge and Yukawa couplings, respectively. Leading two-loop corrections are
taken into account by means of appropriately defined running quark masses.Comment: LaTeX, 12 pages incl. 3 figures. V.2: slightly rewritten to allow for
a more general phase convention. Fixed some typos and added one referenc
Chargino Pair Production at Colliders with Polarized Beams
The chargino system can be reconstructed completely
in collisions. By measuring the total cross sections and the
asymmetries with polarized beams in , the chargino masses and the gaugino-higgsino mixing angles of these
states can be determined very accurately. If only the lightest charginos
are kinematically accessible, transverse beam polarization
is needed to determine the mixing angles unambiguously. From these observables
the fundamental SUSY parameters can be derived: the SU(2) gaugino mass ,
the modulus and the cosine of the CP-violating phase of the higgsino mass
parameter , and , the ratio of the vacuum expectation
values of the two neutral Higgs doublet fields. [The remaining two-fold
ambiguity of the phase can be resolved by measuring the normal polarization of
the charginos.]Comment: 19 pages including 4 figure
CP Phases in Supersymmetric Tri-lepton Signals at the Tevatron
We have analyzed the supersymmetric tri-lepton signals for sparticle searches
at the Tevatron in the minimal supersymmetric standard model with general CP
phases without generational mixing. The CP phases may affect very strongly the
chargino and neutralino mass spectrums and
as well as and . Even under the stringent
constraints from the electron electric dipole moment the CP phases can lead to
a minimum of the tri-lepton event rate for their non-trivial values.Comment: 10 pages, 3 eps figures, largely revised by including the electron
EDM constraint
CP asymmetries in neutralino production in e+e- collisions
We study two CP sensitive triple-product asymmetries for neutralino
production e+e- \to\tilde\chi^0_i \tilde\chi^0_j and the subsequent leptonic
two-body decay \tilde\chi^0_i \to \tilde l l, \tilde l \to \tilde\chi^0_1 l,
for \l= e,\mu,\tau. We calculate the asymmetries, cross sections and branching
ratios in the Minimal Supersymmetric Standard Model with complex parameters \mu
and M_1. We present numerical results for the asymmetries to be expected at a
linear electron-positron collider in the 500 GeV range. The asymmetries can go
up to 25 %. We estimate the event rates which are necessary to observe the
asymmetries. Polarized electron and positron beams can significantly enhance
the asymmetries and cross sections. In addition, we show how the two decay
leptons can be distinguished by making use of their energy distributions.Comment: 22 pages, 7 figures; typos corrected, version to appear in Phys. Rev.
Probing MSSM Higgs Sector with Explicit CP Violation at a Photon Linear Collider
The CP properties of Higgs bosons can be probed through their s-channel
resonance productions via photon-photon collisions by use of circularly and/or
linearly polarized backscattered laser photons at a TeV-scale linear e^+ e^-
collider. Exploiting this powerful tool, we investigate in detail the Higgs
sector of the minimal supersymmetric Standard Model with explicit CP violation.Comment: 18 pages, 5 figures. Some comments added and typos corrected. To
appear in Phys. Rev.
A T-odd asymmetry in neutralino production and decay
We study CP-violating effects in neutralino production and subsequent decay
within the Minimal Supersymmetric Standard Model with complex parameters M_1
and mu. The observable we propose is a T-odd asymmetry based on a triple
product in neutralino production e^+ e^- -> tilde{chi}^0_i tilde{chi}^0_2, i =
1,...,4, with subsequent leptonic three-body decay tilde{chi}^0_2 ->
tilde{chi}^0_1 l^+ l^-, l = e, mu, at an e^+ e^- linear collider with sqrt{s} =
500 GeV and polarised beams. We provide compact analytical formulae for the
cross section and the T-odd asymmetry taking into account the complete spin
correlations between production and decay. We give numerical predictions for
the cross section and the T-odd asymmetry. The asymmetry can go up to 10 %.Comment: 28 pages, LaTeX, 10 figures; v2: typos corrected, published versio
Tau-Sleptons and Tau-Sneutrino in the MSSM with Complex Parameters
We present a phenomenological study of tau-sleptons stau_1,2 and
tau-sneutrino in the Minimal Supersymmetric Standard Model with complex
parameters A_tau, mu and M_1. We analyse production and decays of stau_1,2 and
tau-sneutrino at a future e^+ e^- collider. We present numerical predictions
for the important decay rates, paying particular attention to their dependence
on the complex parameters. The branching ratios of the fermionic decays of
stau_1 and tau-sneutrino show a significant phase dependence for tan(beta) <
10. For tan(beta) > 10 the branching ratios for the stau_2 decays into Higgs
bosons depend very sensitively on the phases. We show how information on the
phase phi(A_tau) and the other fundamental stau parameters can be obtained from
measurements of the stau masses, polarized cross sections and bosonic and
fermionic decay branching ratios, for small and large tan(beta) values. We
estimate the expected errors for these parameters. Given favorable conditions,
the error of A_tau is about 10% to 20%, while the errors of the remaining stau
parameters are in the range of approximately 1% to 3%. We also show that the
induced electric dipole moment of the tau-lepton is well below the current
experimental limit.Comment: LaTex, 25 pages, 11 figures (included); v2: extended discussion on
error determination, version to appear in Phys.Rev.
Probing the MSSM Higgs Boson Sector with Explicit CP Violation through Third Generation Fermion Pair Production at Muon Colliders
We perform a systematic study of the production of a third-generation
fermion-pair, for , and t in the minimal
supersymmetric standard model (MSSM) with explicit CP violation, which is
induced radiatively by soft trilinear interactions related to squarks of the
third generation. We classify all the observables for probing the CP property
of the Higgs bosons constructed by the initial muon beam polarization along
with the unpolarized final fermions and with the final-fermion polarization
configuration of equal helicity, respectively. The observables allow for
complete determination of CP property of the neutral Higgs bosons. The
interference between the Higgs boson and gauge boson contributions also could
provide a powerful method for the determination of the CP property of two heavy
Higgs bosons in the top-quark pair production near the energy region of the
Higgs-boson resonances. For the lightest Higgs-boson mass there is no sizable
interference between scalar and vector contributions for the determination of
the CP property of the lightest Higgs boson. We give a detailed numerical
analysis to show how the radiatively-induced CP violation in the Higgs sector
of the MSSM can be measured.Comment: 30 pages, 7 figures including 5 eps ones. Typos corrected and
references added. To appear in Phys. Rev.
Diagonalization of the neutralino mass matrix and boson-neutralino interaction
We analyze a connection between neutralino mass sign, parity and structure of
the neutralino-boson interaction. Correct calculation of spin-dependent and
spin-independent contributions to neutralino-nuclear scattering should consider
this connection. A convenient diagonalization procedure, based on the
exponetial parametrization of unitary matrix, is suggested.Comment: 21 pages, RevTex
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