5,696 research outputs found
The experimental status of direct searches for exotic physics beyond the standard model at the Large Hadron Collider
The standard model of particle physics is an extremely successful theory of
fundamental interactions, but it has many known limitations. It is therefore
widely believed to be an effective field theory that describes interactions
near the TeV scale. A plethora of strategies exist to extend the standard
model, many of which contain predictions of new particles or dynamics that
could manifest in proton-proton collisions at the Large Hadron Collider (LHC).
As of now, none have been observed, and much of the available phase space for
natural solutions to outstanding problems is excluded. If new physics exists,
it is therefore either heavy (i.e. slightly above the reach of current
searches) or hidden (i.e. currently indistinguishable from standard model
backgrounds). We summarize the existing searches, and discuss future directions
at the LHC.Comment: 33 pages, 7 figure
Thinking outside the ROCs: Designing Decorrelated Taggers (DDT) for jet substructure
We explore the scale-dependence and correlations of jet substructure
observables to improve upon existing techniques in the identification of highly
Lorentz-boosted objects. Modified observables are designed to remove
correlations from existing theoretically well-understood observables, providing
practical advantages for experimental measurements and searches for new
phenomena. We study such observables in jet tagging and provide
recommendations for observables based on considerations beyond signal and
background efficiencies
Benefits to the U.S. from Physicists Working at Accelerators Overseas
We illustrate benefits to the U.S. economy and technological infrastructure
of U.S. participation in accelerators overseas. We discuss contributions to
experimental hardware and analysis and to accelerator technology and
components, and benefits stemming from the involvement of U.S. students and
postdoctoral fellows in global scientific collaborations. Contributed to the
proceedings of the Snowmass 2013 Community Summer Study.Comment: 23 pages, 1 figur
Explainable AI for ML jet taggers using expert variables and layerwise relevance propagation
A framework is presented to extract and understand decision-making
information from a deep neural network (DNN) classifier of jet substructure
tagging techniques. The general method studied is to provide expert variables
that augment inputs ("eXpert AUGmented" variables, or XAUG variables), then
apply layerwise relevance propagation (LRP) to networks both with and without
XAUG variables. The XAUG variables are concatenated with the intermediate
layers after network-specific operations (such as convolution or recurrence),
and used in the final layers of the network. The results of comparing networks
with and without the addition of XAUG variables show that XAUG variables can be
used to interpret classifier behavior, increase discrimination ability when
combined with low-level features, and in some cases capture the behavior of the
classifier completely. The LRP technique can be used to find relevant
information the network is using, and when combined with the XAUG variables,
can be used to rank features, allowing one to find a reduced set of features
that capture part of the network performance. In the studies presented, adding
XAUG variables to low-level DNNs increased the efficiency of classifiers by as
much as 30-40\%. In addition to performance improvements, an approach to
quantify numerical uncertainties in the training of these DNNs is presented.Comment: 38 pages, 30 figure
Ursinus College Alumni Journal, November 1966
\u2770 is here • And \u2770 says: Centennial Fund, roll on! • From the President • For Alumni Association leaders, Homecoming Day was some work and plenty of play • An Ursinus specialty: Shaping the future physician • New placement service for alumni • Huck Finn\u27s dilemma is ours • The paradox of urbia • The theatre of the absurd emerges in Latin America • An age of reforming in liberal education: Trends at Ursinus compare with reforms proposed at Columbia University • Sporting scene: Women undefeated in hockey; Soccer; Cross country; Football • Campus clippings: Founders\u27 Day; Sigma Xi Club; Research at Ursinus; Student teachers; The Agency; Mr. Rue remembers; On army duty; Evening school grows; Neighbors come to dinner; Lindback scholar; Parents Day; Job opportunity; \u2767 Ruby underway • Class notebook • Weddings • Births • In memoriamhttps://digitalcommons.ursinus.edu/alumnijournal/1085/thumbnail.jp
Jet Substructure at the Tevatron and LHC: New results, new tools, new benchmarks
In this report we review recent theoretical progress and the latest
experimental results in jet substructure from the Tevatron and the LHC. We
review the status of and outlook for calculation and simulation tools for
studying jet substructure. Following up on the report of the Boost 2010
workshop, we present a new set of benchmark comparisons of substructure
techniques, focusing on the set of variables and grooming methods that are
collectively known as "top taggers". To facilitate further exploration, we have
attempted to collect, harmonise, and publish software implementations of these
techniques.Comment: 53 pages, 17 figures. L. Asquith, S. Rappoccio, C. K. Vermilion,
editors; v2: minor edits from journal revision
Measurement of the Dipion Mass Spectrum in X(3872) -> J/Psi Pi+ Pi- Decays
We measure the dipion mass spectrum in X(3872)--> J/Psi Pi+ Pi- decays using
360 pb-1 of pbar-p collisions at 1.96 TeV collected with the CDF II detector.
The spectrum is fit with predictions for odd C-parity (3S1, 1P1, and 3DJ)
charmonia decaying to J/Psi Pi+ Pi-, as well as even C-parity states in which
the pions are from Rho0 decay. The latter case also encompasses exotic
interpretations, such as a D0-D*0Bar molecule. Only the 3S1 and J/Psi Rho
hypotheses are compatible with our data. Since 3S1 is untenable on other
grounds, decay via J/Psi Rho is favored, which implies C=+1 for the X(3872).
Models for different J/Psi-Rho angular momenta L are considered. Flexibility in
the models, especially the introduction of Rho-Omega interference, enable good
descriptions of our data for both L=0 and 1.Comment: 7 pages, 4 figures -- Submitted to Phys. Rev. Let
Precision measurement of the top quark mass from dilepton events at CDF II
We report a measurement of the top quark mass, M_t, in the dilepton decay
channel of
using an integrated luminosity of 1.0 fb^{-1} of p\bar{p} collisions collected
with the CDF II detector. We apply a method that convolutes a leading-order
matrix element with detector resolution functions to form event-by-event
likelihoods; we have enhanced the leading-order description to describe the
effects of initial-state radiation. The joint likelihood is the product of the
likelihoods from 78 candidate events in this sample, which yields a measurement
of M_{t} = 164.5 \pm 3.9(\textrm{stat.}) \pm 3.9(\textrm{syst.})
\mathrm{GeV}/c^2, the most precise measurement of M_t in the dilepton channel.Comment: 7 pages, 2 figures, version includes changes made prior to
publication by journa
Cross Section Measurements of High- Dilepton Final-State Processes Using a Global Fitting Method
We present a new method for studying high- dilepton events
(, , ) and simultaneously
extracting the production cross sections of , , and p\bar{p} \to \ztt at a center-of-mass energy of TeV. We perform a likelihood fit to the dilepton data in a parameter
space defined by the missing transverse energy and the number of jets in the
event. Our results, which use of data recorded with the CDF
II detector at the Fermilab Tevatron Collider, are pb, pb, and
\sigma(\ztt) =291^{+50}_{-46} pb.Comment: 20 pages, 2 figures, to be submitted to PRD-R
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