53 research outputs found
Ultraviolet photoelectron spectroscopy of molybdenum and molybdenum monoxide anions
Journal ArticleThe 351 nm photoelectron spectra of Mo-and MoO- have been measured. The electron affinity of atomic molybdenum is 0.748(2) eV and that of molybdenum monoxide is 1.290(6) eV. The term energies of several MoO electronic states not previously observed are obtained and compared with ab initio predictions. The ground state of MoO is confirmed to have 5II symmetry and the term energy of the 3II excited state, 10 179(20) cm21, closely matches calculations. The ground state of MoO2 is a 4P state with a vibrational frequency of 810(40) cm-1. The first excited state of molybdenum monoxide is tentatively assigned as a 3? state with T0=621(50) cm21. At least one state, possibly a 5?+ state, lies 8000(500) cm-1 above the ground state, and a 5?- state is observed at 11 590(60) cm-1 above the ground state. The separations of spin?orbit levels for the MoO X 5II, 3II, and 3? states are 169(30), 410(20), and 2720(20) cm-1, respectively. The vibrational frequencies of the 3II and 3? states are found to be 600(20) and 1000(20) cm-1, respectively. These observations give new insight into the Mo?O bond
Gluon-Induced Weak Boson Fusion
The gluon-gluon induced terms for Higgs production through weak boson fusion
(WBF) are computed. Formally, these are of NNLO in the strong coupling
constant. This is the lowest order at which non-zero color exchange occurs
between the scattering quarks, leading to a color field and thus additional
hadronic activity between the outgoing jets. Using a minimal set of cuts, the
numerical impact of these terms is at the percent level with respect to the NLO
rate for weak boson fusion. Applying the so-called WBF cuts leads to an even
stronger suppression, so that we do not expect a significant deterioration of
the WFB signal by these color exchange effects.Comment: 9 pages, 8 figures (21 included ps- and eps-files
Charged Higgs Production at Linear Colliders in Large Extra Dimensions
In the Two-Higgs-Doublet Model(2HDM) with large extra dimensions(LED), we
study the contributions of virtual Kaluza-Klein(KK) gravitons to 2HDM charged
Higgs production, especially in the two important production processes
and , at future linear colliders
(LC). We find that KK graviton effects can significantly modify these total
cross sections and also their differential cross sections compared to their
respective 2HDM values and, therefore, can be used to probe the effective scale
up to several TeV. For example, at TeV, the cross
sections for and in the 2HDM are
7.4fb for GeV and 0.003fb for TeV and
, while in LED they are 12.1fb and 0.01fb, respectively, for
Tev.Comment: 18 pages, 11 figures; a version to appear in PR
Suppression of Heavy Ion gamma gamma Production of the Higgs by Coulomb Dissociation
Predicted two-photon Higgs production with heavy ions at LHC is shown to be
reduced due to the large Coulomb dissociation cross section. Incorporating the
effect of dissociation reduces the production of a 100 GeV Higgs by about a
factor of three compared to rates in the literature calculated without this
effect.Comment: 5 pages, latex, revtex source, two postscript figure
Supersymmetric Electroweak Corrections to Single Top Quark Production at the Fermilab Tevatron
We have calculated the supersymmetric
electroweak corrections to single top quark production via at the Fermilab Tevatron in the minimal supersymmetric model. The
supersymmetric electroweak corrections to the cross section are a few percent
for , and can exceed 10% for . The combined effects
of SUSY electroweak corrections and the Yukawa corrections can exceed 10% for
favorable parameter values, which might be observable at a high-luminosity
Tevatron.Comment: 13 pages, 4 figures available at reques
Moderate Supersymmetric CP Violation
It is well known that supersymmetry (SUSY) gives neutron and electron
electric dipole moments ( and ) which are too large by about
. If we assume a SUSY model cannot contain fine-tunings or large mass
scales, then one must require that the SUSY breaking mechanism give real soft
breaking parameters, in which case the minimal SUSY model has no violation
other than from the CKM matrix (besides possible strong violating
effects). We show that in non-minimal SUSY models, a moderate amount of
violation can be induced through one loop corrections to the scalar potential,
giving an effective phase of order , and thus implying and
can be near their current experimental bounds . This moderate amount
of SUSY violation could also prove important for models of electroweak
baryogenesis. We illustrate our results with a specific model.Comment: 19pp plain LATEX, 1 fig (by EMAIL request), TRI-PP-93-86. (Some
clarifying comments about renormalizability added--version to appear in Phys.
Rev. D
Single top quark production as a probe of R-parity-violating SUSY at pp and p\bar p colliders
We investigate the ability of single top quark production via qq'->
squark->tb and q \bar q'->slepton->t\bar b at the LHC and Tevatron to probe the
strength of R-parity violating couplings in the minimal supersymmetric model.
We found that given the existing bounds on R-parity violating couplings, single
top quark production may be greatly enhanced over that predicted by the
standard model, and that both colliders can either discover R-parity violating
SUSY or set strong constraints on the relevant R-parity violating couplings. We
further found that the LHC is much more powerful than the Tevatron in probing
the squark couplings, but the two colliders have comparable sensitivity for the
slepton couplings.Comment: 15 pages, 4 figure
Supersymmetric effects in top quark decay into polarized W-boson
We investigate the one-loop supersymmetric QCD (SUSY-QCD) and electroweak
(SUSY-EW) corrections to the top quark decay into a b-quark and a longitudinal
or transverse W-boson. The corrections are presented in terms of the
longitudinal ratio \Gamma(t-->W_L b)/\Gamma(t--> W b) and the transverse ratio
\Gamma(t-->W_- b)/\Gamma(t--> W b). In most of the parameter space, both
SUSY-QCD and SUSY-EW corrections to these ratios are found to be less than 1%
in magnitude and they tend to have opposite signs. The corrections to the total
width \Gamma(t-->W b) are also presented for comparison with the existing
results in the literature. We find that our SUSY-EW corrections to the total
width differ significantly from previous studies: the previous studies give a
large correction of more than 10% in magnitude for a large part of the
parameter space while our results reach only few percent at most.Comment: Version in PRD (explanation and refs added
Status of Muon Collider Research and Development and Future Plans
The status of the research on muon colliders is discussed and plans are
outlined for future theoretical and experimental studies. Besides continued
work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy
collider, many studies are now concentrating on a machine near 0.1 TeV (CoM)
that could be a factory for the s-channel production of Higgs particles. We
discuss the research on the various components in such muon colliders, starting
from the proton accelerator needed to generate pions from a heavy-Z target and
proceeding through the phase rotation and decay ()
channel, muon cooling, acceleration, storage in a collider ring and the
collider detector. We also present theoretical and experimental R & D plans for
the next several years that should lead to a better understanding of the design
and feasibility issues for all of the components. This report is an update of
the progress on the R & D since the Feasibility Study of Muon Colliders
presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A.
Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics
(Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics,
Accelerators and Beam
Searching for Higgs : From LEP towards LHC
After a brief introduction to the theoretical basis of the Higgs mechanism
for generating the masses of elementary particles, the experimental searches
for Higgs particles will be summarized, from bounds at LEP to inferences for
LHC. The report will focus on the Standard Model, though some central results
on extended Higgs systems, as conjectured for example in supersymmetric
theories, will also be recapitulated. Alternative scenarios based on
spontaneous symmetry breaking by novel strong interactions are adumbrated at
the theoretical level.Comment: Added reference
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