776 research outputs found
Gravitational Forces in the Randall-Sundrum Model with a Scalar Stabilizing Field
We consider the problem of gravitational forces between point particles on
the branes in a five dimensional (5D) Randall-Sundrum model with two branes (at
and ) and symmetry of the fifth dimension. The matter on
the branes is viewed as a perturbation on the vacuum metric and treated to
linear order. In previous work \cite{ad} it was seen that the trace of the
transverse part of the 4D metric on the TeV brane, , contributed a
Newtonian potential enhanced by and thus
produced gross disagreement with experiment. In this work we include a scalar
stabilizing field and solve the coupled Einstein and scalar equations to
leading order for the case where is small and the vacuum
field is a decreasing function of . then grows a mass
factor where however, is suppressed from its natural value,
, by an exponential factor ,
. Thus agreement with experiment depends on the interplay
between the enhancing and decaying exponentials. Current data eliminates a
significant part of the parameter space, and the Randall-Sundrum model will be
sensitive to any improvements on the tests of the Newtonian force law at
smaller distances.Comment: 22 pages, Fig.1 adde
Modified Signals for Supersymmetry in the NMSSM with a Singlino-like LSP
In the framework of the NMSSM with a singlino-like LSP, we study
quantitatively the impact of the additional bino -> singlino cascade on the
efficiencies in several search channels for supersymmetry of the ATLAS and CMS
collaborations. Compared to the MSSM, the additional cascade reduces the
missing transverse energy, but leads to additional jets or leptons. For the
NMSSM benchmark lines which generalize cMSSM benchmark points, the efficiencies
in the most relevant 2/3 jet + missing energy search channels can drop by
factors ~1/3 to ~1/7, and can reduce the present lower bounds on M_{1/2} by as
much as ~0.9 - 0.75 in the NMSSM for large bino-singlino mass differences. The
larger efficiencies in multijet or multilepton search channels are not strong
enough to affect this conclusion. In the fully constrained cNMSSM, sparticle
decay cascades via the lightest stau can lead to signal cross sections in
multilepton and 2tau search channels which are potentially visible at the LHC
with 7 TeV center of mass energy.Comment: 24 pages, 9 Figures, misprint in Table 1 correcre
Discovering the Higgs Through Highly-Displaced Vertices
We suggest that the Higgs could be discovered at the Tevatron or the LHC
(perhaps at the LHCb detector) through decays with one or more substantially
displaced vertices from the decay of new neutral particles. This signal may
occur with a small but measurable branching fraction in the recently-described
``hidden valley'' models, hep-ph/0604261; weakly-coupled models with multiple
scalars, including those of hep-ph/0511250, can also provide such signals,
potentially with a much larger branching fraction. This decay channel may
extend the Higgs mass reach for the Tevatron. Unusual combinations of b jets,
lepton pairs and/or missing energy may accompany this signal.Comment: v2, minor improvements/clarifications, one added referenc
NMSSM Higgs Discovery at the LHC
We demonstrate that Higgs discovery at the LHC is possible in the context of
the NMSSM even for those scenarios such that the only strongly produced Higgs
boson is a very SM-like CP-even scalar which decays almost entirely to a pair
of relatvely light CP-odd states. In combination with other search channels, we
are on the verge of demonstrating that detection of at least one of the NMSSM
Higgs bosons is guaranteed at the LHC for accumulated luminosity of .Comment: 8 pages, 1 figure, to appear in the Proceedings of the Les Houches
Workshop 2003: ``Physics at TeV Colliders'
Involuntary Hospitalization for the Mentally Ill Under Florida\u27s Baker Act: Procedural Due Process and the Role of the Attorney
Functional Callan-Symanzik equation for QED
An exact evolution equation, the functional generalization of the
Callan-Symanzik method, is given for the effective action of QED where the
electron mass is used to turn the quantum fluctuations on gradually. The usual
renormalization group equations are recovered in the leading order but no
Landau pole appears.Comment: 9 pages, no figure
The Higgs Sector in a Extension of the MSSM
We consider the Higgs sector in an extension of the MSSM with extra SM
singlets, involving an extra gauge symmetry, in which the
domain-wall problem is avoided and the effective parameter is decoupled
from the new gauge boson mass. The model involves a rich Higgs
structure very different from that of the MSSM. In particular, there are large
mixings between Higgs doublets and the SM singlets, significantly affecting the
Higgs spectrum, production cross sections, decay modes, existing exclusion
limits, and allowed parameter range. Scalars considerably lighter than the LEP2
bound (114 GeV) are allowed, and the range is both allowed
and theoretically favored. Phenomenologically, we concentrate our study on the
lighter (least model-dependent, yet characteristic) Higgs particles with
significant SU(2)-doublet components to their wave functions, for the case of
no explicit CP violation in the Higgs sector. We consider their spectra,
including the dominant radiative corrections to their masses from the top/stop
loop. We computed their production cross sections and reexamine the existing
exclusion limits at LEP2. We outline the searching strategy for some
representative scenarios at a future linear collider. We emphasize that
gaugino, Higgsino, and singlino decay modes are indicative of extended models
and have been given little attention. We present a comprehensive list of model
scenarios in the Appendices.Comment: 49 pages, 17 figure
Global fit to Higgs signal strengths and couplings and implications for extended Higgs sectors
The most recent LHC data have provided a considerable improvement in the
precision with which various Higgs production and decay channels have been
measured. Using all available public results from ATLAS, CMS and the Tevatron,
we derive for each final state the combined confidence level contours for the
signal strengths in the (gluon fusion + ttH associated production) versus
(vector boson fusion + VH associated production) space. These "combined signal
strength ellipses" can be used in a simple, generic way to constrain a very
wide class of New Physics models in which the couplings of the Higgs boson
deviate from the Standard Model prediction. Here, we use them to constrain the
reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and
vector boson pairs. We also consider New Physics contributions to the
loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as
invisible/unseen decays. Finally, we apply our fits to some simple models with
an extended Higgs sector, in particular to Two-Higgs-Doublet models of Type I
and Type II, the Inert Doublet model, and the Georgi-Machacek triplet Higgs
model.Comment: 31 pages, 15 figures; v2: fixed important factor of 2 missing in Eq.
(1) (results unchanged), extended discussion in the next-to-last paragraph of
Section 3, some references added; v3: appendices and references added,
matches version accepted by PR
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