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D. Acosta

Publications and source records attributed to D. Acosta.

At least 55 records · Page 3Linked to original sources
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↗
arXiv2004

Search for Bs->mu+mu- and Bd->mu+mu- Decays in ppbar Collisions at sqrt(s)=1.96 TeV

We report on a search for Bs->mu+mu- and Bd->mu+mu- decays in ppbar collisions at sqrt(s)=1.96 TeV using 171 pb-1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the Standard Model. One event survives all our selection requirements,consistent with the background expectation. We derive branching ratio limits of BR(Bs->mu+mu-) < 5.8 x 10^-7 and BR(Bd->mu+mu-) < 1.5 x 10^-7 at 90% confidence level.

hep-ex↗
arXiv2004

Search for Doubly-Charged Higgs Bosons Decaying to Dileptons in ppbar Collisions at sqrt(s)=1.96 TeV

We present the results of a search for doubly-charged Higgs bosons (H+/-+/-) decaying to dileptons using ~240/pb of ppbar collision data collected by the CDF II experiment at the Fermilab Tevatron. In our search region, given by same-sign dilepton mass m_ll' > 80 GeV/c^2 (100 GeV/c^2 for dielectron channel), we observe no evidence for doubly-charged Higgs production. We set limits on sigma (ppbar --> H++H-- --> l+l+l-l-) as a function of the mass of the doubly-charged Higgs boson and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, we derive lower mass limits on H+/-+/-_L of 133 GeV/c^2, 136 GeV/c^2, and 115 GeV/c^2 in the ee, mu mu, and e mu channels, respectively, and a lower mass limit of 113 GeV/c^2 on H+/-+/-_R in the mu mu channel, all at the 95% confidence level.

hep-ex↗
arXiv2004

Search for Kaluza-Klein Graviton Emission in $p\bar{p}$ Collisions at $\sqrt{s}=1.8$ TeV using the Missing Energy Signature

We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 ${pb}^{-1}$ of \ppb collisions at $\sqrt{s}$ = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a $3+1+n$-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for $n$=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.

hep-ex↗
arXiv2003

Measurement of Prompt Charm Meson Production Cross Sections in p anti-p Collisions at s**(1/2) = 1.96 TeV

We report on measurements of differential cross sections d sigma/d p_t for prompt charm meson production in p anti-p collisions at s**(1/2) = 1.96 TeV using 5.8 +/- 0.3 pb-1 of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y| \leq 1 in four fully reconstructed decay modes: D0 --> K- pi+, D*+ -> D0 pi+, D+ --> K- pi+ pi+, D+_s--> phi pi+, and their charge conjugates. The measured cross sections are compared to theoretical calculations.

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↗
arXiv2003

Heavy flavor properties of jets produced in $p\bar{p}$ interactions at $sqrt{s}=$ 1.8 TeV

We present a detailed examination of the heavy flavor properties of jets produced at the Fermilab Tevatron collider. The data set, collected with the Collider Detector at Fermilab, consists of events with two or more jets with transverse energy $E_T \geq 15$ GeV and pseudo-rapidity $|η| \leq 1.5$. The heavy flavor content of the data set is enriched by requiring that at least one of the jets (lepton-jet) contains a lepton with transverse momentum larger than 8 GeV/c. Jets containing hadrons with heavy flavor are selected via the identification of secondary vertices. The parton-level cross sections predicted by the {\sc herwig} Monte Carlo generator program are tuned within theoretical and experimental uncertainties to reproduce the secondary-vertex rates in the data. The tuned simulation provides new information on the origin of the discrepancy between the $b\bar{b}$ cross section measurements at the Tevatron and the next-to-leading order QCD prediction. We also compare the rate of away-jets (jets recoiling against the lepton-jet) containing a soft lepton ($p_T \geq 2$ GeV/c) in the data to that in the tuned simulation. We find that this rate is larger than what is expected for the conventional production and semileptonic decay of pairs of hadrons with heavy flavor.

hep-ex↗
arXiv2003

Inclusive Double Pomeron Exchange at the Fermilab Tevatron pbar-p Collider

We report a study of $\bar p+p\to \bar p+X+Y$ at $\sqrt s=1800$ GeV, where $Y$ is a proton or system of mass-squared $M_Y^2\lesssim 8$ GeV$^2$. In a sample of events with a leading $\bar p$ of fractional momentum loss $0.035<ξ_{\bar p}<0.095$ and 4-momentum transfer squared $|t_{\bar p}|<1.0$ GeV$^2$, the proton fractional momentum loss $ξ_p^X$ to the system $X$ was evaluated from the momenta of the particles comprising $X$. In the region $ξ_p^X<0.02$, the $ξ_p^X$ distribution behaves as $\sim 1/(ξ_p^X)^{1.1}$, as expected for double Pomeron exchange. The fraction of events with $ξ_p^X<0.02$ is found to be $0.194\pm 0.001 {\rm (stat)}\pm 0.012 {\rm (syst)}$.

hep-ex↗
arXiv2003

Measurement of the average time-integrated mixing probability of b-flavored hadrons produced at the Tevatron

We have measured the number of like-sign (LS) and opposite-sign (OS) lepton pairs arising from double semileptonic decays of $b$ and $\bar{b}$-hadrons, pair-produced at the Fermilab Tevatron collider. The data samples were collected with the Collider Detector at Fermilab (CDF) during the 1992-1995 collider run by triggering on the existence of $μμ$ and $e μ$ candidates in an event. The observed ratio of LS to OS dileptons leads to a measurement of the average time-integrated mixing probability of all produced $b$-flavored hadrons which decay weakly, $\barχ = 0.152 \pm 0.007$ (stat.) $\pm 0.011$ (syst.), that is significantly larger than the world average $\barχ = 0.118 \pm 0.005$.

hep-ex↗
arXiv2003

Search for the Flavor-Changing Neutral Current Decay D^0\toμ^+μ^- in p\bar{p} Collisions at \sqrt{s}=1.96 TeV

We report on a search for the flavor-changing neutral current decay D^0\toμ^+μ^- in p\bar{p} collisions at \sqrt{s}=1.96 TeV using 65\ipb of data collected by the CDF II experiment at the Fermilab Tevatron Collider. A displaced-track trigger selects long-lived D^0 candidates in the D^0\toμ^+μ^- search channel, the kinematically similar D^0\toπ^+π^- channel used for normalization, the Cabbibo-favored D^0\to K^+π^- channel used to optimize the selection criteria in an unbiased manner, and their charge conjugates. Finding no signal events in the D^0\toμ^+μ^- search window, we set an upper limit on the branching fraction {\cal B}(D^0\toμ^+μ^-)\leq 2.5E-6 (3.3E-6) at the 90% (95%) confidence level.

hep-ex↗
arXiv2003

A 3-D Track-Finding Processor for the CMS Level-1 Muon Trigger

We report on the design and test results of a prototype processor for the CMS Level-1 trigger that performs 3-D track reconstruction and measurement from data recorded by the cathode strip chambers of the endcap muon system. The tracking algorithms are written in C++ using a class library we developed that facilitates automatic conversion to Verilog. The code is synthesized into firmware for field-programmable gate-arrays from the Xilinx Virtex-II series. A second-generation prototype has been developed and is currently under test. It performs regional track-finding in a 60 degree azimuthal sector and accepts 3 GB/s of input data synchronously with the 40 MHz beam crossing frequency. The latency of the track-finding algorithms is expected to be 250 ns, including geometrical alignment correction of incoming track segments and a final momentum assignment based on the muon trajectory in the non-uniform magnetic field in the CMS endcaps.

physics.ins-det↗
arXiv2003

Central Pseudorapidity Gaps in Events with a Leading Antiproton at the Fermilab Tevatron pbar-p Collider

We report a measurement of the fraction of events with a large pseudorapidity gap $Δη$ within the pseudorapidity region available to the proton dissociation products $X$ in $\bar p+p\to \bar p+X$. For a final state $\bar p$ of fractional momentum loss $ξ_{\bar p}$ and 4-momentum transfer squared $t_{\bar p}$ within $0.06<ξ_{\bar p}<0.09$ and $|t_{\bar p}|<1.0$ [0.2] GeV$^2$ at $\sqrt s=1800$ [630] GeV, the fraction of events with $Δη>3$is found to be $0.246\pm 0.001 {\rm (stat)}\pm 0.042 {\rm (syst)}$ [$0.184\pm 0.001 {\rm (stat)}\pm 0.043 {\rm (syst)}$]. Our results are compared with gap fractions measured in minimum bias $\bar pp$ collisions and with theoretical expectations.

hep-ex↗
arXiv2003

Search for the Supersymmetric Partner of the Top Quark in Dilepton Events from p-pbar Collisions at 1.8 TeV

We have searched for the supersymmetric partner of the top quark (stop) in 107 pb^{-1} of p-pbar collisions at \sqrt{s}= 1.8 TeV collected by the Collider Detector at Fermilab (CDF). Within the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM) each of the pair-produced stops is assumed to decay into a lepton, bottom quark and supersymmetric neutrino. Such a scenario would give rise to events with two leptons, two hadronic jets, and a substantial imbalance of transverse energy. No evidence of such a stop signal has been found. We calculate a 95% confidence level (C.L.) upper limit on the stop production cross section, which excludes stop masses in the region (80<m_{\stop}<135 GeV/c^2) in the mass plane of stop versus sneutrino.

hep-ex↗
arXiv2002

Search for Long-lived Charged Massive Particles in anti-p p Collisions at s**1/2 = 1.8 TeV

We report a search for production of long-lived charged massive particles in a data sample of 90 pb^{-1} of \sqrt{s} = 1.8 TeV p anti-p collisions recorded by the Collider Detector at Fermilab (CDF). The search uses the muon-like penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data is found to agree with background expectations, and cross section limits of \cal{O} (1) pb are derived using two reference models, a stable quark and a stable scalar lepton.

hep-ex↗
arXiv2002

Search for a W' Boson Decaying to a Top and Bottom Quark Pair in 1.8 TeV p-pbar Collisions

We report the results of a search for a W' boson produced in p-pbar collisions at a center-of-mass energy of 1.8 TeV using a 106 pb-1 data sample recorded by the Collider Detector at Fermilab. We observe no significant excess of events above background for a W' boson decaying to a top and bottom quark pair, with the top quark subsequently decaying into a semileptonic final state. These data allow us to set limits on the rate of W' boson production and decay. In a model where this boson would mediate interactions involving a massive right-handed neutrino (nu_R) and has Standard Model strength couplings, we exclude a W' boson with mass between 225 and 536 GeV/c**2 at 95% confidence level for M_W' >> M_nu_R and between 225 and 566 GeV/c**2 at 95% confidence level for M_W' < M_nu_R.

hep-ex↗
arXiv2002

Search for New Physics in Photon-Lepton Events in pbar-p Collisions at root-s= 1.8 TeV

We present the results of a search in pbar-p collisions at root-s=1.8 TeV for anomalous production of events containing a photon and a lepton (e or mu), both with large transverse energy, using 86 pb-1 of data collected with the Collider Detector at Fermilab during the 1994-95 collider run at the Fermilab Tevatron. The presence of large missing transverse energy, additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large missing transverse energy, for which the observed total is 16 events and the expected mean total is 7.6 \pm 0.7 events.

hep-ex↗
arXiv2002

Comparison of the Isolated Direct Photon Cross Sections in $p \bar p$ Collisions at $\sqrt{s}=1.8$ TeV and $\sqrt{s}=0.63$ TeV

We have measured the cross sections $d^2σ/dP_T dη$ for production of isolated direct photons in \pbarp collisions at two different center-of-mass energies, 1.8 TeV and 0.63 TeV, using the Collider Detector at Fermilab (CDF). The normalization of both data sets agree with the predictions of Quantum Chromodynamics (QCD) for photon transverse momentum ($P_T$) of 25 GeV/c, but the shapes versus photon $P_T$ do not. These shape differences lead to a significant disagreement in the ratio of cross sections in the scaling variable $x_T (\equiv 2P_T/\sqrt{s}$). This disagreement in the $x_T$ ratio is difficult to explain with conventional theoretical uncertainties such as scale dependence and parton distribution parameterizations.

hep-ex↗