Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session P9: Higgs Searches II |
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Sponsoring Units: DPF Chair: Rob Roser, Fermi National Accelerator Laboratory Room: Maryland A |
Monday, February 15, 2010 10:45AM - 10:57AM |
P9.00001: New techniques for improving $Z \rightarrow \mu\mu$ acceptance for the SM Higgs search in the $ZH \rightarrow \ell^{+} \ell^{-} b\bar{b}$ final state at CDF Justin Pilot We present a method for significantly increasing potential signal acceptance for the standard model (SM) Higgs search in the $ZH \rightarrow \ell \ell b \bar{b}$ final state. Currently, this channel provides comparable Higgs production limits with respect to other low mass search channels at CDF despite suffering from a minimal production cross section times branching ratio. Muons from the decay of a $Z$ boson are currently found by requiring a track matched with associated hits in the muon chambers. Using a loosened muon selection algorithm in combination with a missing transverse energy trigger leads to additional signal acceptance without significantly increasing the ratio of signal to background events in the sample. The potential improvement in Higgs search sensitivity from this new lepton selection algorithm is shown. [Preview Abstract] |
Monday, February 15, 2010 10:57AM - 11:09AM |
P9.00002: Search for Associated Production of $Z$ and Higgs Bosons in the $\ell \ell bb$ Final State in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV Betty Calpas We present a search for a low mass standard model Higgs boson produced in association with a $Z$ boson decaying to two electrons or two muons at a center-of-mass energy of $\sqrt{s}=$1.96~TeV with the D0 detector at the Fermilab Tevatron collider. The search is performed in events containing one or two $b$-tagged jets with of order 4~fb$^{-1}$ of data, employing multivariate techniques for signal-to-background discrimination. No significant excess above standard model expectations is observed, and upper limits on the Higgs production cross section are derived. Recent improvements to the sensitivity will also be discussed. [Preview Abstract] |
Monday, February 15, 2010 11:09AM - 11:21AM |
P9.00003: Search for Associated Production of $Z$ and Higgs Bosons in the $ \nu \nu bb$ Final State in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV Abhinav Dubey We present a search for a low mass Standard Model Higgs boson produced in association with a $Z$ boson decaying invisibly into a pair of neutrinos at a center-of-mass energy of $\sqrt{s}=$1.96~TeV with the D0 detector at the Fermilab Tevatron collider. The final state is characterized by the presence of two $b$-tagged jets from the Higgs boson decay and a large imbalance in the transverse energy of the event. This channel is very powerful because of the large $Z\to \nu\nu$ branching ratio, but is experimentally very challenging because of the large QCD backgrounds and absence of visible leptons in the final state. The result with a data set up to 5.2~fb$^{-1}$ and recent improvements to the sensitivity will be discussed. [Preview Abstract] |
Monday, February 15, 2010 11:21AM - 11:33AM |
P9.00004: Improvements in tau identification and energy scale calibration at DZero Romain Madar Many high energy physics processes whether from standard model origin or beyond include a $\tau$ lepton in their signatures. $\tau$ lepton signatures can then be of particular importance in many physics analyses such as top quark related measurements as well as Higgs boson or supersymmetry searches. $\tau$ leptons decay inside the detector ($c\tau= 87.1\mu$m), hence they are identified by their decay products: electrons, muons and hadrons. Different physical objects have similar experimental signatures and need to be discriminated from real tau decay. We present the current status and the future plans of $\tau$ reconstruction at the DZero experiment from the identification (using multivariate methods) to the $\tau$ energy scale calibration. [Preview Abstract] |
Monday, February 15, 2010 11:33AM - 11:45AM |
P9.00005: Search for the standard model Higgs boson in the $\tau\tau q \bar q$ final state Katy Tschann-Grimm We present a search for a low mass Standard Model Higgs boson in events with a final state containing two taus and two jets, in which one tau decays to either a muon or an electron and the other tau decays to hadrons. The search uses data from the D0 experiment with an integrated luminosity of 5 fb$^{-1}$. The final states are sensitive to a combination of associated production of a $W/Z$ boson with a Higgs boson, vector boson fusion and gluon-gluon fusion production processes. No signal is yet detected, and upper limits are placed on the cross section times branching ratio of Standard Model Higgs production. [Preview Abstract] |
Monday, February 15, 2010 11:45AM - 11:57AM |
P9.00006: Search for a Standard Model Higgs boson in the $WH\to \tau\nu b \bar{b}$ channel with 4.0 fb$^{-1}$ at D0 Melvin Meijer We present a search for a low mass ($m_H<135$~GeV) Standard Model Higgs boson in a 4.0~fb$^{-1}$ dataset of proton antiproton collisions at 1.96~TeV center-of-mass energy, recorded by the D0 detector at the Tevatron collider. This search was specifically aimed at the Higgs boson decaying to a $b-\overline{b}$ pair, with an associated $W$ boson which decays into a hadronically decaying tau and a tau-neutrino. We require large missing transverse energy, a jet identified as a hadronic tau and to optimize acceptance, we require only loose $b$ identification requirements on two jets, or one jet with tight $b$ identification requirements. This analysis was done using Boosted Decision Trees and in the end a limit was set on Standard Model Higgs boson production. [Preview Abstract] |
Monday, February 15, 2010 11:57AM - 12:09PM |
P9.00007: Search for SM Higgs in associated production with a $W$ boson in the $\tau\nu b\bar{b}$ final state at CDF Elisabetta Pianori We present a search for the associated production of a standard model (SM) Higgs boson and a $W$ boson in data collected by the CDF detector in $p\overline{p}$ collisions at $\sqrt{s}=$ 1.96~TeV corresponding to 2fb$^{-1}$ of integrated luminosity. The search is performed using events containing two jets, a hadronically decaying $\tau$ lepton and missing transverse energy corresponding to the decay products expected from the decays of $H \rightarrow b\bar{b}$ and $W \rightarrow \tau \nu$. A binned likelihood fit of the dijet mass to the expectations for signal and background is performed to test for a potential Higgs signal. In the absence of an observed excess, we set upper limits on the production rate times branching ratio for a potential Higgs boson as a function of its mass. [Preview Abstract] |
Monday, February 15, 2010 12:09PM - 12:21PM |
P9.00008: Search for a SM Higgs Boson in the all-hadronic decay channel at CDF Ankush Mitra We present a search for the standard model (SM) Higgs boson in the $VH \rightarrow qq' b\bar{b}$ ($V = W$,$Z$) and $Hqq' \rightarrow b\bar{b} qq'$ (vector boson fusion) production modes using 4fb$^{-1}$ of $p\bar{p}$ collisions recorded with the CDF detector. These channels contain significant acceptance from a potential signal as a result of the large hadronic branching ratios for the $W$ and $Z$ bosons. However, the analysis of this channel is difficult due to the presence of very large multi-jet backgrounds. The most recent result in this channels which is presented here yields a factor of two improvement over the previous 2fb$^{-1}$ analysis. We describe new techniques used for data-based modelling of the multi-jet backgrounds and for incorporating jet shapes to suppress some of these backgrounds. [Preview Abstract] |
Monday, February 15, 2010 12:21PM - 12:33PM |
P9.00009: Search for Neutral Supersymmetric Higgs Bosons in $bbb(b)$ Final States in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV Nicolas Osman We present a search for the Higgs boson in the $hb(b) \to b\bar{b}bb$ channel at a center of mass energy of 1.96 TeV using $\sim$5 fb$^{-1}$ of data collected with the D0 detector at the Tevatron. In many supersymmetric models, the coupling of the Higgs bosons to bottom quarks is enhanced in comparison to the Standard Model leading to significantly increased production rates. The $h\to b\bar{b}$ is the dominant decay process for much of the parameter space. This fully hadronic channel presents two particular challenges: modeling the multijet background requires great care, and the multi b-jet signal leads to further complications. An event-based approach has been introduced to address the latter and increase sensitivity. [Preview Abstract] |
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