1,433 research outputs found
Inclusive Semileptonic B Decays at BABAR
We report updates on two analyses of inclusive semileptonic B decays based on
a dataset of 89 million BB events recorded with the BABAR detector at the Y(4S)
resonance. Events are selected by fully reconstructing the decay of one B meson
and identifying a charged lepton from the decay of the other B meson. In the
first analysis, the measurement of the first and second moment of the hadronic
mass distribution in Cabibbo-favored B ->X_c l nu decays allows for the
determination of the nonperturbative parameters and
of Heavy Quark Effective Theory (HQET) and |Vcb|. In the second analysis, the
hadronic mass distribution is used to measure the inclusive charmless
semileptonic branching fraction and to determine |Vub|.Comment: 3 pages, 4 postscript figures, submitted to EPS 200
Study of Bs->mu+mu- in CMS
We present a Monte Carlo simulation study of measuring the rare leptonic
decay Bs->mu+mu- with the CMS experiment at the LHC. The study is based on a
full detector simulation for signal and background events. We discuss the
high-level trigger algorithm and the offline event selection.Comment: 4 pages, 3 figures; to appear in the proceedings of the 33rd Intl.
Conference on High Energy Physics, ICHEP 2006 (Moscow, July 2006
Recent results on decays with the CMS experiment
Results on decays with the CMS experiment are reported,
using 61 fb of data recorded during LHC Run 1 and 2016. With an improved
muon identification algorithm and refined unbinned maximum likelihood fitting
methods, the decay is observed with a significance of
5.6 standard deviations. Its branching fraction is measured to be BF() = [2.9+/-0.7(exp)+/-0.2(frag)], where the first
error is the combined statistical and systematic uncertainty and the second
error quantifies the uncertainty of the and fragmentation
probability ratio. The effective lifetime is
ps. No evidence for the decay is found and an upper limit of BF() <
3.6 (at 95% confidence level) is determined. All results are
consistent with the standard model of particle physics.Comment: Invited short review submitted to MPL
SM and MSSM Higgs Boson Production: Spectra at large transverse Momentum
Strategies for Higgs boson searches require the knowledge of the total
production cross section and the transverse momentum spectrum. The large
transverse momentum spectrum of the Higgs boson produced in gluon fusion can be
quite different in the Standard Model and the Minimal Supersymmetric Standard
Model. In this paper we present a comparison of the Higgs transverse momentum
spectrum obtained using the PYTHIA event generator and the HIGLU program as
well as the program HQT, which includes NLO corrections and a soft gluon
resummation for the region of small transverse momenta. While the shapes of the
spectra are similar for the Standard Model, significant differences are
observed in the spectra of Minimal Supersymmetric Standard Model benchmark
scenarios with large tan(beta).Comment: 8 pages, 13 figure
In-memory Realization of In-situ Few-shot Continual Learning with a Dynamically Evolving Explicit Memory
Continually learning new classes from a few training examples without
forgetting previous old classes demands a flexible architecture with an
inevitably growing portion of storage, in which new examples and classes can be
incrementally stored and efficiently retrieved. One viable architectural
solution is to tightly couple a stationary deep neural network to a dynamically
evolving explicit memory (EM). As the centerpiece of this architecture, we
propose an EM unit that leverages energy-efficient in-memory compute (IMC)
cores during the course of continual learning operations. We demonstrate for
the first time how the EM unit can physically superpose multiple training
examples, expand to accommodate unseen classes, and perform similarity search
during inference, using operations on an IMC core based on phase-change memory
(PCM). Specifically, the physical superposition of a few encoded training
examples is realized via in-situ progressive crystallization of PCM devices.
The classification accuracy achieved on the IMC core remains within a range of
1.28%--2.5% compared to that of the state-of-the-art full-precision baseline
software model on both the CIFAR-100 and miniImageNet datasets when continually
learning 40 novel classes (from only five examples per class) on top of 60 old
classes.Comment: Accepted at the European Solid-state Devices and Circuits Conference
(ESSDERC), September 202
Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant
Jet event rates in deep inelastic ep scattering at HERA are investigated
applying the modified JADE jet algorithm. The analysis uses data taken with the
H1 detector in 1994 and 1995. The data are corrected for detector and
hadronization effects and then compared with perturbative QCD predictions using
next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2)
is determined evaluating the jet event rates. Values of alpha_S(Q^2) are
extracted in four different bins of the negative squared momentum
transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the
renormalization group equation to these several alpha_S(Q^2) values results in
alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys.
J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4
Measurement of Leading Proton and Neutron Production in Deep Inelastic Scattering at HERA
Deep--inelastic scattering events with a leading baryon have been detected by
the H1 experiment at HERA using a forward proton spectrometer and a forward
neutron calorimeter. Semi--inclusive cross sections have been measured in the
kinematic region 2 <= Q^2 <= 50 GeV^2, 6.10^-5 <= x <= 6.10^-3 and baryon p_T
<= MeV, for events with a final state proton with energy 580 <= E' <= 740 GeV,
or a neutron with energy E' >= 160 GeV. The measurements are used to test
production models and factorization hypotheses. A Regge model of leading baryon
production which consists of pion, pomeron and secondary reggeon exchanges
gives an acceptable description of both semi-inclusive cross sections in the
region 0.7 <= E'/E_p <= 0.9, where E_p is the proton beam energy. The leading
neutron data are used to estimate for the first time the structure function of
the pion at small Bjorken--x.Comment: 30 pages, 9 figures, 2 tables, submitted to Eur. Phys.
Jets and energy flow in photon-proton collisions at HERA
Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to \overline{p}p data and QCD calculations. The comparisons show that the \gamma p events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections d\sigma/dE_T^{jet} and d\sigma/d\eta^{jet} are measured
Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV
Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
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