arXiv subjects

T. Affolder

Publications and source records attributed to T. Affolder.

At least 19 recordsLinked to original sources

arXiv2017

Prototyping of petalets for the Phase-II Upgrade of the silicon strip tracking detector of the ATLAS Experiment

In the high luminosity era of the Large Hadron Collider, the HL-LHC, the instantaneous luminosity is expected to reach unprecedented values, resulting in about 200 proton-proton interactions in a typical bunch crossing. To cope with the resultant increase in occupancy, bandwidth and radiation damage, the ATLAS Inner Detector will be replaced by an all-silicon system, the Inner Tracker (ITk). The ITk consists of a silicon pixel and a strip detector and exploits the concept of modularity. Prototyping and testing of various strip detector components has been carried out. This paper presents the developments and results obtained with reduced-size structures equivalent to those foreseen to be used in the forward region of the silicon strip detector. Referred to as petalets, these structures are built around a composite sandwich with embedded cooling pipes and electrical tapes for routing the signals and power. Detector modules built using electronic flex boards and silicon strip sensors are glued on both the front and back side surfaces of the carbon structure. Details are given on the assembly, testing and evaluation of several petalets. Measurement results of both mechanical and electrical quantities are shown. Moreover, an outlook is given for improved prototyping plans for large structures.

physics.ins-det↗

arXiv2005

Search for First-Generation Scalar Leptoquarks in $\bm{p \bar{p}}$ collisions at $\sqrt{s}$=1.96 TeV

We report on a search for pair production of first-generation scalar leptoquarks ($LQ$) in $p \bar{p}$ collisions at $\sqrt{s}$=1.96 TeV using an integrated luminosity of 203 $pb^{-1}$ collected at the Fermilab Tevatron collider by the CDF experiment. We observe no evidence for $LQ$ production in the topologies arising from $LQ \bar{LQ} \to eqeq$ and $LQ \bar{LQ} \to eq νq$, and derive 95% C.L. upper limits on the $LQ$ production cross section. %as a function of $β$, where $β$ is the branching fraction for $LQ \to eq$. The results are combined with those obtained from a separately reported CDF search in the topology arising from $LQ\bar{LQ} \to νq νq$ and 95% C.L. lower limits on the LQ mass as a function of $β= BR(LQ \to eq) $ are derived. The limits are 236, 205 and 145 GeV/c$^2$ for $β$ = 1, $β$ = 0.5 and $β$ = 0.1, respectively.

hep-ex↗

arXiv2004

Comparison of Three-jet Events in Proton-Antiproton Collisions at Center-of-mass Energy 1.8 TeV to Predictions from a Next-to-leading Order QCD Calculation

The properties of three-jet events with total transverse energy greater than 320 GeV and individual jet energy greater than 20 GeV have been analyzed and compared to absolute predictions from a next-to-leading order (NLO) perturbative QCD calculation. These data, of integrated luminosity 86 pb^-1, were recorded by the CDF Experiment for proton-antiproton collisions at sqrt{s}=1.8 TeV. This study tests a model of higher order QCD processes that result in gluon emission and can be used to estimate the magnitude of the contribution of processes higher than NLO. The total cross section is measured to be 466 +/- 3(stat.)^{+207}_{-70}(syst.) pb. The differential cross section is furthermore measured for all kinematically accessible regions of the Dalitz plane, including those for which the theoretical prediction is unreliable. While the measured cross section is consistent with the theoretical prediction in magnitude, the two differ somewhat in shape in the Dalitz plane.

hep-ex↗

arXiv2003

Observation of the Narrow State $X(3872)\to J/ψπ^{+}π^{-}$ in $\bar{p}p$ Collisions at $\sqrt{s}=1.96 \TeV$

We report the observation of a narrow state decaying into $J/ψπ^+π^-$ and produced in $220 pb^{-1}$ of $\bar{p} p $ collisions at $\sqrt{s}=1.96 TeV$ in the CDF II experiment. We observe $ 730 \pm 90 $ decays. The mass is measured to be $3871.3 \pm 0.7 (stat) \pm 0.4 (syst) MeV/c2$, with an observed width consistent with the detector resolution. This is in agreement with the recent observation by the Belle Collaboration of the X(3872) meson.

hep-ex↗

arXiv2001

Diffractive Dijet Production at sqrt(s)=630 and 1800 GeV at the Fermilab Tevatron

We report a measurement of the diffractive structure function $F_{jj}^D$ of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in $\bar pp$ collisions at $\sqrt s=630$ GeV at the Fermilab Tevatron. The ratio of $F_{jj}^D$ at $\sqrt s=630$ GeV to $F_{jj}^D$ obtained from a similar measurement at $\sqrt s=1800$ GeV is compared with expectations from QCD factorization and with theoretical predictions. We also report a measurement of the $ξ$ ($x$-Pomeron) and $β$ ($x$ of parton in Pomeron) dependence of $F_{jj}^D$ at $\sqrt s=1800$ GeV. In the region $0.035<ξ<0.095$, $|t|<1$ GeV$^2$ and $β<0.5$, $F_{jj}^D(β,ξ)$ is found to be of the form $β^{-1.0\pm 0.1} ξ^{-0.9\pm 0.1}$, which obeys $β$-$ξ$ factorization.

hep-ex↗

arXiv2001

Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron $\bar pp$ Collider

We report a measurement of the strong coupling constant, $α_s(M_Z)$, extracted from inclusive jet production in $p\bar{p}$ collisions at $\sqrt{s}=$1800 GeV. The QCD prediction for the evolution of $α_s$ with jet transverse energy $E_T$ is tested over the range 40<$E_T$<450 GeV using $E_T$ for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. In the text we discuss the data-theory comparison in the region from 250 to 450 GeV. The value of $α_s$ at the mass of the $Z^0$ boson averaged over the range 40<$E_T$<250 GeV is found to be $α_s(M_{Z})= 0.1178 \pm 0.0001{(\rm stat)}^{+0.0081}_{-0.0095}{\rm (exp. syst)}$. The associated theoretical uncertainties are mainly due to the choice of renormalization scale ($^{+6%}_{-4%}$) and input parton distribution functions (5%).

hep-ex↗

arXiv2001

Double Diffraction Dissociation at the Fermilab Tevatron Collider

We present results from a measurement of double diffraction dissociation in $\bar pp$ collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width $Δη^0>3$ (overlapping $η=0$) is found to be $4.43\pm 0.02{(stat)}{\pm 1.18}{(syst) mb}$ [$3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}$] at $\sqrt{s}=1800$ [630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.

hep-ex↗

arXiv2001

Observation of Diffractive $J/ψ$ Production at the Fermilab Tevatron

We report the first observation of diffractive $J/ψ(\to μ^+μ^-)$ production in $\bar pp$ collisions at $\sqrt{s}$=1.8 TeV. Diffractive events are identified by their rapidity gap signature. In a sample of events with two muons of transverse momentum $p_T^μ>2$ GeV/$c$ within the pseudorapidity region $|η|<$1.0, the ratio of diffractive to total $J/ψ$ production rates is found to be $R_{J/ψ}= [1.45\pm 0.25]%$. The ratio $R_{J/ψ}(x)$ is presented as a function of $x$-Bjorken. By combining it with our previously measured corresponding ratio $R_{jj}(x)$ for diffractive dijet production, we extract a value of $0.59\pm 0.15$ for the gluon fraction of the diffractive structure function of the proton.

hep-ex↗

arXiv2001

Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV

We present results of searches for diphoton resonances produced both inclusively and also in association with a vector boson (W or Z) using 100 pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on the product of cross section times branching ratio for both p\bar p\toγγ+ X and p\bar p\toγγ+ W/Z. Comparing the inclusive production to the expectations from heavy sgoldstinos we derive limits on the supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the sgoldstino mass and the choice of other parameters. Also, using a NLO prediction for the associated production of a Higgs boson with a W or Z boson, we set an upper limit on the branching ratio for H\toγγ. Finally, we set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which couples only to γ, W, and Z$ bosons with standard model couplings) of 82 GeV/c^2 at 95% confidence level.

hep-ex↗

arXiv2001

Search for Quark-Lepton Compositeness and a Heavy Wprime Boson Using the e-nu Channel in p-pbar Collisions at sqrt(s) = 1.8 TeV

We present searches for quark-lepton compositeness and a heavy W' boson at high electron-neutrino transverse mass. We use ~110/pb of data collected in p-pbar collisions at sqrt(s) = 1.8 TeV by the CDF collaboration during 1992--95. The data are consistent with standard model expectations. Limits are set on the quark-lepton compositeness scale Lambda and the ratio of partial cross sections sigma (W' -> e nu) / sigma (W -> e nu). The cross section ratio is used to obtain a lower limit on the mass of a W' boson with standard model couplings. We exclude Lambda < 2.81 TeV and a W' boson with mass below 754 GeV/c^2 at the 95% confidence level. We combine the W' mass limit with our previously published limit obtained using the muon channel, to exclude a W' boson with mass below 786 GeV/c^2 at the 95% confidence level.

hep-ex↗

arXiv2001

Measurement of dsigma/DM Forward-Backward Charge Asymmetry for High Mass Drell-Yan e+e- Pairs from p-pbar Collisions at sqrt(s)=1.8 TeV

We report on a measurement of the mass dependence of the forward-backward charge asymmetry, A_FB, and production cross section dsigma/dM for e+e- pairs with mass M_ee>40 GeV/c2. The data sample consists of 108 pb-1 of p-pbar collisions at sqrt(s)=1.8 TeV taken by the Collider Detector at Fermilab during 1992-1995. The measured asymmetry and dsigma/dM are compared with the predictions of the Standard Model and a model with an extra Z' gauge boson.

hep-ex↗

arXiv2001

Cross Section and Heavy Quark Composition of Photon+Muon Events Produced in ppbar Collisions

We present a measurement of the cross section and the first measurement of the heavy flavor content of associated direct photon + muon events produced in hadronic collisions. These measurements come from a sample of 1.8 TeV ppbar collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily due to Compton scattering process charm+gluon -> charm+photon, with the final state charm quark producing a muon. The cross section for events with a photon transverse momentum between 12 and 40 GeV/c is measured to be 46.8+-6.3+-7.5 pb, which is two standard deviations below the most recent theoretical prediction. A significant fraction of the events in the sample contain a final-state bottom quark. The ratio of charm to bottom production is measured to be 2.4+-1.2, in good agreement with QCD models.

hep-ex↗

arXiv2001

Measurement of the W Boson Mass with the Collider Detector at Fermilab

We present a measurement of the W boson mass using data collected with the CDF detector during the 1994-95 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 30,115 W -> enu events recorded in an integrated luminosity of 84 pb^(-1) gives a mass Mw = 80.473 +- 0.065(stat.) +- 0.092(syst.) GeV/c^2. A fit to the transverse mass spectrum of a sample of 14,740 W -> munu events from 80 pb^(-1) gives a mass Mw = 80.465 +- 0.100(stat.) +- 0.103(syst.) GeV/c^2. The dominant contributions to the systematic uncertainties are the uncertainties in the electron energy scale and the muon momentum scale, 0.075 GeV/c^2 and 0.085 GeV/c^2, respectively. The combined value for the electron and muon channel is Mw = 80.470 +- 0.089 GeV/c^2. When combined with previously published CDF measurements, we obtain Mw = 80.433 +- 0.079 GeV/c^2.

hep-ex↗

arXiv2001

Measurement of the Inclusive Jet Cross Section in ${\bar p p}$ collisions at $\sqrt{s}=1.8$ TeV

We present results from the measurement of the inclusive jet cross section for jet transverse energies from 40 to 465 GeV in the pseudo-rapidity range $0.1<|η|<0.7$. The results are based on 87 $pb^{-1}$ of data collected by the CDF collaboration at the Fermilab Tevatron Collider. The data are consistent with previously published results. The data are also consistent with QCD predictions given the flexibility allowed from current knowledge of the proton parton distributions. We develop a new procedure for ranking the agreement of the parton distributions with data and find that the data are best described by QCD predictions using the parton distribution functions which have a large gluon contribution at high $E_T$ (CTEQ4HJ).

hep-ph↗

arXiv2000

Measurement of J/Psi and Psi(2S) Polarization in ppbar Collisions at sqrt(s) = 1.8 TeV

We have measured the polarization of J/Psi and Psi(2S) mesons produced in p\bar{p} collisions at \sqrt{s} = 1.8 TeV, using data collected at CDF during 1992-95. The polarization of promptly produced J/Psi [Psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4[5.5] < P_T < 20 GeV/c and |y| < 0.6. For P_T \gessim 12 GeV/c we do not observe significant polarization in the prompt component.

hep-ex↗

arXiv2000

Measurement of the Decay Amplitudes of B0 --> J/psi K* and B0s --> J/psi phi Decays

A full angular analysis has been performed for the pseudo-scalar to vector-vector decays, B0 --> J/psi K* and B_s --> J/psi phi, to determine the amplitudes for decays with parity-even longitudinal and transverse polarization and parity-odd transverse polarization. The measurements are based on 190 B0 candidates and 40 B_s candidates collected from a data set corresponding to 89 inverse pb of pbarp collisions at root(s) = 1.8 TeV at the Fermilab Tevatron. In both decays the decay amplitude for longitudinal polarization dominates and the parity-odd amplitude is found to be small.

hep-ex↗

arXiv2000

Measurement of Rapidity Distribution for High Mass Drell-Yan ee Pairs at CDF

We report on the first measurement of the rapidity distribution dsigma/dy over nearly the entire kinematic region of rapidity for e^+e^- pairs in the Z-boson region of 66 116 GeV/c^2. The data sample consists of 108 pb^{-1} of ppbar collisions at \sqrt{s}=1.8 TeV taken by the Collider Detector at Fermilab during 1992--1995. The total cross section in the $Z$-boson region is measured to be 252 +- 11 pb. The measured total cross section and dσ/dy are compared with quantum chromodynamics calculations in leading and higher orders.

hep-ex↗

arXiv2000

Search for the Charged Higgs Boson in the Decays of Top Quark Pairs in the $eτ$ and $μτ$ Channels at $\sqrt{s}$=1.8 TeV

Top quark production offers the unique opportunity to search for a charged Higgs boson ($H^\pm$), as the contribution from $t\to H^+b\to τ^+νb$ can be large in extensions of the Standard Model. We use results from a search for top quark pair production by the Collider Detector at Fermilab (CDF) in the e$τ+ \ebar_T$+jets and $μτ+\ebar_T$+jets signatures to set an upper limit on the branching ratio of ${\cal B} (t \to H^{+} b)$ in 106 pb$^{-1}$ of data. The upper limit is in the range 0.5 to 0.6 at 95% C.L. for $H^{+}$ masses in the range 60 to 160 GeV, assuming the branching ratio for {$H^+\to τν$} is 100% . The $τ$ lepton is detected through its 1-prong and 3-prong hadronic decays.

hep-ex↗