4,645 research outputs found
Adaptive Designs for Optimal Observed Fisher Information
Expected Fisher information can be found a priori and as a result its inverse
is the primary variance approximation used in the design of experiments. This
is in contrast to the common claim that the inverse of observed Fisher
information is a better approximation to the variance of the maximum likelihood
estimator. Observed Fisher information cannot be known a priori; however, if an
experiment is conducted sequentially (in a series of runs) the observed Fisher
information from previous runs is available. In the current work two adaptive
designs are proposed that use the observed Fisher information from previous
runs in the design of the current run.Comment: 19 pages, 2 figure
An Effective Lagrangian for Low-Scale Technicolor
We present an effective Lagrangian for low-scale technicolor. It describes
the interactions at energies near the mass of the lowest-lying bound states of
the lightest technifermion doublet -- the spin-one
and the corresponding technipions . This Lagrangian is intended to put
on firmer ground the technicolor straw-man phenomenology used for collider
searches of low-scale technicolor. The technivectors are described using the
hidden local symmetry (HLS) formalism of Bando et al. The Lagrangian is based
on , where
is the electroweak gauge group and is the HLS gauge
group. Special attention is paid to the higher-derivative standard HLS and
Wess-Zumino-Witten interactions needed to describe radiative and other decays
of the and , respectively.Comment: Updated introduction, to appear in Phys. Rev.
Accidental Goldstone Bosons
We study vacuum alignment in theories in which the chiral symmetry of a set
of massless fermions is both spontaneously and explicitly broken. We find that
transitions occur between different phases of the fermions' CP symmetry as
parameters in their symmetry breaking Hamiltonian are varied. We identify a new
phase that we call pseudoCP-conserving. We observe first and second-order
transitions between the various phases. At a second-order (and possibly
first-order) transition a pseudoGoldstone boson becomes massless as a
consequence of a spontaneous change in the discrete, but not the continuous,
symmetry of the ground state. We relate the masslessness of these ``accidental
Goldstone bosons'' (AGBs) bosons to singularities of the order parameter for
the phase transition. The relative frequency of CP-phase transitions makes it
commonplace for the AGBs to be light, much lighter than their underlying strong
interaction scale. We investigate the AGBs' potential for serving as light
composite Higgs bosons by studying their vacuum expectation values, finding
promising results: AGB vevs are also often much less than their strong scale.Comment: 27 pages, latex, with 12 postscript figure
CP violation and mixing in technicolor models
Vacuum alignment in technicolor models provides an attractive origin for the quarks' CP violation and, possibly, a natural solution for the strong-CP problem of QCD. We discuss these topics in this paper. Then we apply them to determine plausible mixing matrices for left and right-handed quarks. These matrices determine the Cabibbo-Kobayashi-Maskawa matrix as well as new mixing angles and phases that are observable in extended technicolor (ETC) and topcolor (TC2) interactions. We determine the contributions of these new interactions to CP-violating and mixing observables in the K0, Bd and Bs systems. Consistency with mixing and CP violation in the K0 system requires assuming that ETC interactions are electroweak generation-conserving even if technicolor has a walking gauge coupling. Large ETC gauge boson masses and small intergenerational mixing then result in negligibly small ETC contributions to B-meson mixing and CP violation and to Re(ϵ′/ϵ). We confirm our earlier strong lower bounds on TC2 gauge boson masses from Bd–¯¯¯Bd mixing. We then pay special attention to the possibility that current experiments indicate a deviation from standard model expectations of the values of sin2β measured in Bd→J/ψKS, ϕKS, η′KS, and πKS, studying the ability of TC2 to account for these. We also determine the TC2 contribution to ΔMBs and to Re(ϵ′/ϵ), and find them to be appreciable.First author draf
Technicolor at the Tevatron
We propose that the 3.2 sigma excess at ~150 GeV in the dijet mass spectrum
of W + jets reported by CDF is the technipion of low-scale technicolor.
Its relatively large cross section is due to production of a narrow
resonance, the technirho, which decays to W + . We discuss ways to
enhance and strengthen the technicolor hypothesis and suggest companion
searches at the Tevatron and LHC.Comment: 5 pages, 6 figures. Note added regarding Z(l+l-)+jj signals at the
Tevatron and LH
Testing the Technicolor Interpretation of CDF's Dijet Excess at the LHC
Under the assumption that the dijet excess seen by the CDF Collaboration near
150 Gev in Wjj production is due to the lightest technipion of the low-scale
technicolor process , we study its observability in
LHC detectors with 1--20 inverse femtobarns of data. We describe interesting
new kinematic tests that can provide independent confirmation of this LSTC
hypothesis. We find that cuts similar to those employed by CDF, and recently by
ATLAS, cannot confirm the dijet signal. We propose cuts tailored to the LSTC
hypothesis and its backgrounds at the LHC that may reveal . Observation of the isospin-related channel and of in the three lepton plus neutrino and dilepton plus dijet modes
will be important confirmations of the LSTC interpretation of the CDF signal.
The channel is experimentally cleaner than and its rate is
known from by phase space. It can be discovered or excluded with the
collider data expected in 2012. The channel is
cleanest of all and its rate is determined from and the LSTC parameter
. This channel and are discussed as
a function of .Comment: 24 pages, 24 figure
Testing the Technicolor Interpretation of the CDF Dijet Excess at the 8-TeV LHC
Under the assumption that the dijet excess seen by the CDF Collaboration near
150 Gev in Wjj production is due to the lightest technipion of the low-scale
technicolor process , we study its observability in
LHC detectors for 8 TeV collisions and 20 inverse femtobarns of integrated
luminosity. We describe interesting new kinematic tests that can provide
independent confirmation of this LSTC hypothesis. We show that cuts similar to
those employed by CDF, and recently by ATLAS, cannot confirm the dijet signal.
We propose cuts tailored to the LSTC hypothesis and its backgrounds at the LHC
that may reveal . Observation of the
isospin-related channel and of in the
and modes will be important
confirmations of the LSTC interpretation of the CDF signal. The
channel is experimentally cleaner than and its rate is known from
by phase space. It can be discovered or excluded with the collider
data expected by the end of 2012. The channel is
cleanest of all and its rate is determined from and the LSTC parameter
. This channel and are discussed as a
function of .Comment: 28 pages, 27 figures, submitted to PRD. arXiv admin note: substantial
text overlap with arXiv:1201.439
Conditional Information and Inference in Response-Adaptive Allocation Designs
Response-adaptive allocation designs refer to a class of designs where the
probability an observation is assigned to a treatment is changed throughout an
experiment based on the accrued responses. Such procedures result in random
treatment sample sizes. Most of the current literature considers unconditional
inference procedures in the analysis of response-adaptive allocation designs.
The focus of this work is inference conditional on the observed treatment
sample sizes. The inverse of information is a description of the large sample
variance of the parameter estimates. A simple form for the conditional
information relative to unconditional information is derived. It is found that
conditional information can be greater than unconditional information. It is
also shown that the variance of the conditional maximum likelihood estimate can
be less than the variance of the unconditional maximum likelihood estimate.
Finally, a conditional bootstrap procedure is developed that, in the majority
of cases examined, resulted in narrower confidence intervals than relevant
unconditional procedures.Comment: 20 pages, 1 figure, 3 tables, 1 supplemental document 4 pages, 3
table
Efficiency of Observed Information Adaptive Designs
In this work the primary objective is to maximize the precision of the
maximum likelihood estimate in a linear regression model through the efficient
design of the experiment. One common measure of precision is the unconditional
mean square error. Unconditional mean square error has been a primary motivator
for optimal designs; commonly, defined as the design that maximizes a concave
function of the expected Fisher information. The inverse of expected Fisher
information is asymptotically equal to the mean square error of the maximum
likelihood estimate. There is a substantial amount of existing literature that
argues the mean square error conditioned on an appropriate ancillary statistic
better represents the precision of the maximum likelihood estimate. Despite
evidence in favor of conditioning, limited effort has been made to find designs
that are optimal with respect to conditional mean square error. The inverse of
observed Fisher information is a higher order approximation of the conditional
mean square error than the inverse of expected Fisher information [Efron and
Hinkley (1978)]. In light of this, a more relevant objective is to find designs
that optimize observed Fisher information. Unlike expected Fisher information,
observed Fisher information depends on the observed data and cannot be used to
design an experiment completely in advance of data collection. In a sequential
experiment the observed Fisher information from past observations is available
to inform the design of the next observation. In this work an adaptive design
that incorporates observed Fisher information is proposed for linear regression
models. It is shown that the proposed design is more efficient, at the limit,
than any fixed design, including the optimal design, with respect to
conditional mean square error.Comment: 25 pages, 3 figures, 1 Table, 1 supplemen
Is Achievement Motivation in Basketball Games Affected by Team or Individual Competitive Situations in Elementary Physical Education Classes?
This study examined the relationship between skill, setting and gender. There were three main purposes for conducting this study. The first was to determine whether a child\u27s achievement motivation changes when participating in a team setting compared to an individual setting. The second purpose was to determine and compare any differences between boys\u27 and girls\u27 achievement motivation, in both team and individual settings, and thirdly, to determine and compare any differences between the achievement motivation of high-skilled and low-skilled children, in both team and individual settings. Subjects were administered the Sport Orientation Questionnaire, (Gill and Deeter, 1988), which assesses competitiveness, win-orientation and goal-orientation. Subjects in this study included a total of 117, (70 female, 47 male), 5th and 6th grade students at Jefferson Elementary School in Charleston, Illinois. Participants were categorized into high and low skill ability, (66 high skilled and 51 low skilled participants). Each student completed the Sport Orientation Questionnaire twice, once for team setting and once for individual setting. Students completed the SOQ, referring to feelings about team basketball competition, after four classes involving five-on-five basketball games. Students completed the SOQ a second time after four classes, which were structured on one-on-one competition. In regards to the primary hypothesis, it was determined that a child\u27s achievement motivation does change when participating in a team setting compared to an individual setting. Results using a 3 way MANOVA indicated six significant differences: 1. Boys are more competitive than girls. 2. High-skilled children are more competitive than low-skilled children. 3. High-skilled children prefer to compete in an individual setting while low-skilled children prefer to compete in a team setting. 4. Both genders and skill levels have a stronger desire to win in a team setting compared to an individual setting. 5. Low-skilled children possess a higher motive to accomplish personal goals in a team setting compared to an individual setting. 6. High-skill participants possess a higher motive to achieve personal goals than low-skilled participants
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