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Blumenfeld, B.

Publications and source records attributed to Blumenfeld, B..

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

High-precision measurement of the W boson mass with the CDF II detector

The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last missing component of the model. After observation of the Higgs boson, a measurement of the W boson mass provides a stringent test of the model. We measure the W boson mass, M W , using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera–electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million W boson candidates is used to obtain M W = 80,433.5 ± 6.4 stat ± 6.9 syst = 80,433.5 ± 9.4 MeV/c 2 , the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega–electron volts; c, speed of light in a vacuum). This measurement is in significant tension with the standard model expectation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Web Proxy Auto Discovery for the WLCG

All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids registered in the ATLAS Grid Information System (AGIS) and CMS SITECONF files, cross-checked with squids registered by sites in the Grid Configuration Database (GOCDB) and the OSG Information Management (OIM) system, and combined with some exceptions manually configured by people from ATLAS and CMS who operate WLCG Squid monitoring. WPAD servers at CERN respond to http requests from grid nodes all over the world with a PAC file that lists available web proxies, based on IP addresses matched from a database that contains the IP address ranges registered to organizations. Large grid sites are encouraged to supply their own WPAD web servers for more flexibility, to avoid being affected by short term long distance network outages, and to offload the WLCG WPAD servers at CERN. The CERN WPAD servers additionally support requests from jobs running at non-grid sites (particularly for LHC@Home) which it directs to the nearest publicly accessible web proxy servers. Furthermore, the responses to those requests are geographically ordered based on a separate database that maps IP addresses to longitude and latitude.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2017

Observation of the Y (4140) structure in the J/ψΦ mass spectrum in B±→ J/ψΦK ± decays

Here, the observation of the $Y(4140)$ structure in $B^\pm\rightarrow J/\psi\,\phi K^\pm$ decays produced in $\bar{p} p $ collisions at $\sqrt{s}=1.96~TeV$ is reported with a statistical significance greater than 5 standard deviations. A fit to the $J/\psi\,\phi$ mass spectrum is performed assuming the presence of a Breit-Wigner resonance. The fit yields a signal of $19^{+6}_{-5}$ resonance events, and resonance mass and width of $4143.4^{+2.9}_{-3.0}(\mathrm{stat})\pm0.6(\mathrm{syst}) ~MeVcc$ and $15.3^{+10.4}_{-6.1}(\mathrm{stat})\pm2.5(\mathrm{syst})~MeVcc$ respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the D + -meson production cross section at low transverse momentum in p p ¯ collisions at s = 1.96 TeV

We report on a measurement of the D + -meson production cross section as a function of transverse momentum (p T ) in proton-antiproton (p$\bar{p}$) collisions at 1.96 TeV center-of-mass energy, using the full data set collected by the Collider Detector at Fermilab in Tevatron Run II and corresponding to 10 fb -1 of integrated luminosity. We use D + →K - π + π + decays fully reconstructed in the central rapidity region |y|<1 with transverse momentum down to 1.5 GeV/c, a range previously unexplored in p$\bar{p}$ collisions. Inelastic p$\bar{p}$ scattering events are selected online using minimally biasing requirements followed by an optimized offline selection. The K - π + π + mass distribution is used to identify the D + signal, and the D + transverse impact-parameter distribution is used to separate prompt production, occurring directly in the hard-scattering process, from secondary production from b-hadron decays. We obtain a prompt D + signal of 2950 candidates corresponding to a total cross section σ(D + ,1.5 T <14.5 GeV/c,|y|<1)=71.9±6.8(stat)±9.3(syst) μb. While the measured cross sections are consistent with theoretical estimates in each p T bin, the shape of the observed p T spectrum is softer than the expectation from quantum chromodynamics. The results are unique in p$\bar{p}$ collisions and can improve the shape and uncertainties of future predictions.

(K-↗
DOE OSTI2016

Measurement of the W W and W Z production cross section using final states with a charged lepton and heavy-flavor jets in the full CDF Run II data set

We present a measurement of the total WW and WZ production cross sections in $p\bar{p}$ collision at $\sqrt{s}$ = 1.96 TeV, in a final state consistent with leptonic W boson decay and jets originating from heavy-flavor quarks from either a W or a Z boson decay. This analysis uses the full data set collected with the CDF II detector during Run II of the Tevatron collider, corresponding to an integrated luminosity of 9.4 fb -1 . An analysis of the dijet mass spectrum provides 3.7σ evidence of the summed production processes of either WW or WZ bosons with a measured total cross section of σ WW+WZ = 13.7±3.9 pb. Independent measurements of the WW and WZ production cross sections are allowed by the different heavy-flavor decay patterns of the W and Z bosons and by the analysis of secondary-decay vertices reconstructed within heavy-flavor jets. The productions of WW and of WZ dibosons are independently seen with significances of 2.9σ and 2.1σ, respectively, with total cross sections of σ WW = 9.4±4.2 pb and σ WZ = 3.7$+2.5\atop{-2.2}$ pb. Lastly, the measurements are consistent with standard-model predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of sin 2 θ eff lept using e + e - pairs from γ * / Z bosons produced in p p ¯ collisions at a center-of-momentum energy of 1.96 TeV

Here, at the Fermilab Tevatron proton-antiproton (p$\bar{p}$) collider, Drell-Yan lepton pairs are produced in the process p$\bar{p}$→e + e - +X through an intermediate γ*/Z boson. The forward-backward asymmetry in the polar-angle distribution of the e - as a function of the e + e - -pair mass is used to obtain sin 2 θ$lept\atop{eff}$, the effective leptonic determination of the electroweak-mixing parameter sin2θW. The measurement sample, recorded by the Collider Detector at Fermilab (CDF), corresponds to 9.4 fb -1 of integrated luminosity from p$\bar{p}$ collisions at a center-of-momentum energy of 1.96 TeV, and is the full CDF Run II data set. The value of sin 2 θ$lept\atop{eff}$ is found to be 0.23248±0.00053. The combination with the previous CDF measurement based on μ + μ - pairs yields sin 2 θ$lept\atop{eff}$=0.23221±0.00046. This result, when interpreted within the specified context of the standard model assuming sin 2 θW=1-M$2\atop{W}$/M$2\atop{Z}$ and that the W- and Z-boson masses are on-shell, yields sin 2 θW=0.22400±0.00045, or equivalently a W-boson mass of 80.328±0.024 GeV/c 2 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Measurement of the forward-backward asymmetry in low-mass bottom-quark pairs produced in proton-antiproton collisions

Here, we report a measurement of the forward-backward asymmetry, AFB, in $b\bar{b}$ pairs produced in proton-antiproton collisions and identified by muons from semileptonic b-hadron decays. The event sample is collected at a center-of-mass energy of √s = 1.96 TeV with the CDF II detector and corresponds to 6.9 fb –1 of integrated luminosity. We obtain an integrated asymmetry of A FB ($b\bar{b}$)=(1.2±0.7)% at the particle level for b-quark pairs with invariant mass, m $b\bar{b}$ , down to 40 GeV/c 2 and measure the dependence of A FB ($b\bar{b}$) on m $b\bar{b}$ . The results are compatible with expectations from the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Study of the energy dependence of the underlying event in proton-antiproton collisions

We study charged particle production (p(T) > 0.5 GeV/c, vertical bar eta vertical bar < 0.8) in proton-antiproton collisions at total center-of-mass energies root s = 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta - phi space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

Aaltonen, T.↗
DOE OSTI2015

Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $\bf V_{tb}$

In this study, we present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb -1 per experiment. The t-channel cross section is measured to be σ t = 2.25$+0.29\atop{-0.31}$ pb. We also present the combinations of the two-dimensional measurements of the s- vs t-channel cross section. In addition, we give the combination of the s+t channel cross section measurement resulting in σ s+t = 3.30$+0.52\atop{-0.40}$ pb, without assuming the standard model value for the ratio σ s /σ t . The resulting value of the magnitude of the top-to-bottom quark coupling is |V tb |= 1.02$+0.06\atop{-0.05}$, corresponding to |V tb | > 0.92 at the 95% C.L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗