Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CDF”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Small-scale signatures of primordial non-Gaussianity in k-nearest neighbour cumulative distribution functions

ABSTRACT Searches for primordial non-Gaussianity in cosmological perturbations are a key means of revealing novel primordial physics. However, robustly extracting signatures of primordial non-Gaussianity from non-linear scales of the late-time Universe is an open problem. In this paper, we apply k-Nearest Neighbour cumulative distribution functions, kNN-CDFs, to the quijote-png simulations to explore the sensitivity of kNN-CDFs to primordial non-Gaussianity. An interesting result is that for halo samples with $M_\mathrm{ h}\langle 10^{14}$ M$_\odot$ $h^{-1}$, the kNN-CDFs respond to equilateral PNG in a manner distinct from the other parameters. This persists in the galaxy catalogues in redshift space and can be differentiated from the impact of galaxy modelling, at least within the halo occupation distribution (HOD) framework considered here. kNN-CDFs are related to counts-in-cells and, through mapping a subset of the kNN-CDF measurements into the count-in-cells picture, we show that our results can be modelled analytically. A caveat of the analysis is that we only consider the HOD framework, including assembly bias. It will be interesting to validate these results with other techniques for modelling the galaxy–halo connection, e.g. (hybrid) effective field theory or semi-analytical methods.

Coulton, William R. (ORCID:0000000212973673)↗
DOE OSTI2019

Nuclear-dominated accretion flows in two dimensions – II. Ejecta dynamics and nucleosynthesis for CO and ONe white dwarfs

We study mass ejection from accretion discs formed in the merger of a white dwarf with a neutron star or black hole. These discs are mostly radiatively inefficient and support nuclear fusion reactions, with ensuing outflows and electromagnetic transients. Here we perform time-dependent, axisymmetric hydrodynamic simulations of these discs including a physical equation of state, viscous angular momentum transport, a coupled 19-isotope nuclear network, and self-gravity. We find no detonations in any of the configurations studied. Our global models extend from the central object to radii much larger than the disc. We evolve these global models for several orbits, as well as alternate versions with an excised inner boundary to much longer times. We obtain robust outflows, with a broad velocity distribution in the range 10 2 –10 4 km s -1 . The outflow composition is mostly that of the initial white dwarf, with burning products mixed in at the |${\lesssim } 10\rm {-}30{{\ \rm per\ cent}}$| level by mass, including up to ~10 -2 M ⊙ of 56 Ni. These heavier elements (plus 4 He) are ejected within ≲ 40° of the rotation axis, and should have higher average velocities than the lighter elements that make up the white dwarf. These results are in broad agreement with previous one- and two-dimensional studies, and point to these systems as progenitors of rapidly rising (~ few day) transients. If accretion on to the central BH/NS powers a relativistic jet, these events could be accompanied by high-energy transients with peak luminosities ~10 47 –10 50 erg s -1 and peak durations of up to several minutes, possibly accounting for events like CDF-S XT2.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

New H erwig7 underlying event tune: From RHIC to LHC energies

We present parameter sets corresponding to new underlying event tunes for the H erwig7.3 Monte Carlo event generator. The existing H erwig tunes are in good agreement with LHC data, however, they are not typically designed for center-of-mass energies below $\sqrt{𝑠}$ = 300 GeV. The tunes presented in this study can describe midrapidity data collected at the nominal RHIC energy of $\sqrt{𝑠}$ = 200 GeV as well as higher center-of-mass energies utilized by experiments at the LHC and Tevatron. The base “New Haven” tune is developed by fitting minimum-bias simulations of proton-proton ($𝑝⁢𝑝$) collisions to midrapidity identified hadron and jet data from the STAR experiment. The “Nashville” tune includes a separate set of parameters developed by tuning to Tevatron proton-antiproton ($𝑝\bar{⁢𝑝}$) data at $\sqrt{𝑠}$ = 300, 900 and 1960 GeV from CDF, and LHC $𝑝⁢𝑝$ measurements from CMS at $\sqrt{𝑠}$ =7 TeV, in addition to the STAR measurements. Both new tunes demonstrate significant improvements over the recommended default tune currently included in the latest version of H erwig for minimum bias production. As such, we advocate using these tunes for future simulation studies at midrapidity by experimental collaborations at RHIC (STAR and sPHENIX) and the LHC (ALICE, ATLAS, and CMS).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Pseudorapidity distributions of charged particles in p-p-bar or p-p collisions at high energies and predictions at ultrahigh energies

Pseudorapidity distributions of charged particles produced in p-p-bar or p-p collisions at different energies were reported by the UA5, UA1, P238, CDF, and ALICE collaborations. A multisource ideal gas model is used to fit the experimental data in this paper. According to the parameter values obtained from fitting the data, we find different linear relationships between different parameters and logarithmic center-of-mass energy. A prediction for the pseudorapidity distributions of charged particles produced in p-p-bar or p-p collisions at the higher Large Hadron Collider energies is given.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Hints of a new leptophilic Higgs sector?

We show that a new leptophilic Higgs sector can resolve some intriguing anomalies in current experimental data across multiple energy ranges. Motivated by the recent CMS excess in the resonant e μ channel at 146 GeV, we consider a leptophilic two-Higgs-doublet model, and propose a novel resonant production mechanism for the neutral components of the second Higgs doublet at the LHC using the lepton content of the proton. Interestingly, the same Yukawa coupling Y e μ ∼ 0.65 – 0.81 that explains the CMS excess also addresses the muon ( g − 2 ) anomaly. Moreover, the new Higgs doublet also resolves the recent CDF W -boson mass anomaly. The relevant model parameter space will be completely probed by future LHC data. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2010

Enhanced B{sub s}-B{sub s} lifetime difference and anomalous like-sign dimuon charge asymmetry from new physics in B{sub s}{yields}{tau}{sup +}{tau}{sup -}

New physics models that increase the decay rate of B{sub s}{yields}{tau}{sup +}{tau}{sup -} contribute to the absorptive part of B{sub s}-B{sub s} mixing, and may enhance {Delta}{Gamma}{sub s} all the way up to its current experimental bound. In particular, the model with a scalar leptoquark can lead to a significant violation of the expectation {Delta}{Gamma}{sub s{<=}{Delta}{Gamma}s} (SM). It can even allow regions in the {Delta}{Gamma}{sub s}-{beta}{sub s} parameter space that are close to the best fit obtained by CDF and D0 through B{sub s}{yields}J/{psi}{phi}. In addition, it can help explain the anomalous like-sign dimuon charge asymmetry observed recently by D0. A measurement of BR(B{sub s}{yields}{tau}{sup +}{tau}{sup -}) is thus crucial for a better understanding of new physics involved in B{sub s}-B{sub s} mixing.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Studying the underlying event in Drell-Yan and high transverse momentum jet production at the Tevatron

We study the underlying event in proton-antiproton collisions by examining the behavior of charged particles produced in association with a large transverse momentum jet ({approx}2.2 fb{sup -1}) or with a Drell-Yan lepton pair ({approx}2.7 fb{sup -1}) in the Z-boson mass region [70<M(pair)<110 GeV/c{sup 2}] as measured by CDF at 1.96 TeV center-of-mass energy. We use the direction of the lepton pair or the leading jet in each event to define regions of {eta}-{phi} space that are sensitive to the modeling of the underlying event. The data are corrected to the particle level to remove detector effects and are then compared with several QCD Monte Carlo models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Rare semileptonic decays of B and B{sub c} mesons in the relativistic quark model

Rare semileptonic decays of B and B{sub c} mesons are investigated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach. Form factors parametrizing the matrix elements of the weak transitions between corresponding meson states are calculated with the complete account of the relativistic effects including contributions of intermediate negative energy states and relativistic transformations of the meson wave functions. The momentum transfer dependence of the form factors is reliably determined in the whole accessible kinematical range. On this basis the total and differential branching fractions of the B{yields}K{sup (*)}l{sup +}l{sup -}({nu}{nu}) and B{sub c}{yields}D{sub s}{sup (*)}l{sup +}l{sup -}({nu}{nu}), B{sub c}{yields}D{sup (*)}l{sup +}l{sup -}({nu}{nu}) decays as well as the longitudinal polarization fractions F{sub L} of the final vector meson and the muon forward-backward asymmetries A{sub FB} are calculated. Good agreement of the obtained results with the recent detailed experimental data on the B{yields}K{sup (*){mu}+{mu}-} decays from Belle and CDF is found. Predictions for the rare semileptonic decays of the B{sub c} mesons are given.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Forward-backward asymmetry of the top quark in diquark models

Motivated by the recent unexpected large forward-backward asymmetry of the top-quark observed by D0 and CDF at the Tevatron, we investigate a possible explanation for the anomaly within the framework of diquark models. In the diquark models, the top-quark pair production is mediated by the u-channel diagram. It is found that the color-triplet diquark can generate the forward-backward asymmetry of 20% when the constraint from the cross section of the top-quark pair production is taken into account.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Measurement of the top pair production cross section in the dilepton decay channel in pp collisions at {radical}(s)=1.96 TeV

A measurement of the tt production cross section in pp collisions at {radical}(s)=1.96 TeV using events with two leptons, missing transverse energy, and jets is reported. The data were collected with the CDF II detector. The result in a data sample corresponding to an integrated luminosity 2.8 fb{sup -1} is {sigma}{sub tt}=6.27{+-}0.73(stat){+-}0.63(syst){+-}0.39(lum) pb. for an assumed top mass of 175 GeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Forward-backward asymmetry of top quark production at the Tevatron in warped extra dimensional models

The CDF and D0 experiments have reported on the measurement of the forward-backward asymmetry of top quark pair production at the Tevatron and the result is that it is more than 2 standard deviations above the predicted value in the standard model. This has to be added to the long-standing anomaly in the forward-backward asymmetry for bottom quark production at LEP which is 3 standard deviations different from the standard model value. The discrepancy in the bottom asymmetry can be accounted for by the contributions of Kaluza-Klein excitations of electroweak gauge bosons at LEP in warped extra-dimensional models in which the fermions are localized differently along the extra dimension so that the gauge interactions of heavy third generation fermions are naturally different from that of light fermions. In this paper, we show that it is more difficult to elaborate a model generating a significant top asymmetry through exchanges of Kaluza-Klein gluons at the Tevatron due to the indirect constraints originating from precision electroweak data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Next-to-leading order QCD predictions for Z,{gamma}*+3-jet distributions at the Tevatron

Using BlackHat in conjunction with SHERPA, we have computed next-to-leading order QCD predictions for a variety of distributions in Z,{gamma}*+1, 2, 3-jet production at the Tevatron, where the Z boson or off-shell photon decays into an electron-positron pair. We find good agreement between the next-to-leading order results for jet p{sub T} distributions and measurements by CDF and D0. We also present jet-production ratios, or probabilities of finding one additional jet. As a function of vector-boson p{sub T}, the ratios have distinctive features which we describe in terms of a simple model capturing leading logarithms and phase-space and parton-distribution-function suppression.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

The 2{sup -+} assignment for the X(3872)

Very recently the BABAR collaboration has put forward a claim that the X(3872) is not a 1{sup ++} resonance, as most of the phenomenological work on the subject was relying on, but rather a 2{sup -+} one. We examine the consequences of this quantum number assignment for the solution of the X(3872) puzzle. The molecular interpretation appears less likely, and the conventional charmonium interpretation should be reconsidered. There are several well-known difficulties with this interpretation, to which we add a new one: the production cross section at CDF is predicted to be much smaller than that observed. We also confirm, using a relativistic string model, the conclusion from potential models that the mass of the state is not consistent with expectations. In the tetraquark interpretation the 2{sup -+} assignment implies a rich spectrum of partner states, although the X(3872) may be among the few which are narrow enough to be observable.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Large loop effects of extra supersymmetric Higgs doublets to CP violation in B{sup 0} mixing

We consider more than one pair of SU(2){sub L} doublet Higgs supermultiplets in a generic supersymmetric extension of the standard model, and calculate their one-loop contributions to the soft mass insertions {delta}{sub LL} etc. We find that, if large supersymmetry breaking in this sector is realized, the loop effects can give rise to large contributions to the soft mass insertions, meaning that they can generate large flavor-changing neutral currents and CP violations. We apply our result to a recently proposed model based on the discrete Q{sub 6} family group, and calculate the nondiagonal matrix element M{sub 12} of the neutral meson systems. We focus our attention on the extra phases {phi}{sub d,s}{sup {Delta}}in B{sub d,s} mixing and flavor-specific CP asymmetries a{sub sl}{sup d,s} in neutral B decays and obtain values that can be about 1 order of magnitude larger than the standard model predictions. Our final results are comparable with the recent experimental observations at D0 and CDF, but they are still about a factor of 5 smaller than the recently measured dimuon asymmetry from D0.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Updated search for the flavor-changing neutral-current decay D{sup 0}{yields}{mu}{sup +}{mu}{sup -} in pp collisions at {radical}(s)=1.96 TeV

We report on a search for the flavor-changing neutral-current decay D{sup 0}{yields}{mu}{sup +}{mu}{sup -} in pp collisions at {radical}(s)=1.96 TeV using 360 pb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D{sup 0} candidates in the {mu}{sup +}{mu}{sup -}, {pi}{sup +}{pi}{sup -}, and K{sup -}{pi}{sup +} decay modes. We use the Cabibbo-favored D{sup 0}{yields}K{sup -}{pi}{sup +} channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D{sup 0}{yields}{pi}{sup +}{pi}{sup -} channel for normalization. We set an upper limit on the branching fraction B(D{sup 0}{yields}{mu}{sup +}{mu}{sup -})<2.1x10{sup -7}(3.0x10{sup -7}) at the 90% (95%) confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Search for the supersymmetric partner of the top quark in pp collisions at {radical}(s)=1.96 TeV

We present a search for the lightest supersymmetric partner of the top quark in proton-antiproton collisions at a center-of-mass energy {radical}(s)=1.96 TeV. This search was conducted within the framework of the R parity conserving minimal supersymmetric extension of the standard model, assuming the stop decays dominantly to a lepton, a sneutrino, and a bottom quark. We searched for events with two oppositely-charged leptons, at least one jet, and missing transverse energy in a data sample corresponding to an integrated luminosity of 1 fb{sup -1} collected by the Collider Detector at Fermilab experiment. No significant evidence of a stop quark signal was found. Exclusion limits at 95% confidence level in the stop quark versus sneutrino mass plane are set. Stop quark masses up to 180 GeV/c{sup 2} are excluded for sneutrino masses around 45 GeV/c{sup 2}, and sneutrino masses up to 116 GeV/c{sup 2} are excluded for stop quark masses around 150 GeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗