Download or read book Search for the Standard Model Higgs Boson in ZH u2192 b bar b Production at D and Evidence for the H u2192 B bar b Decay at the Tevatron written by and published by . This book was released on 2014 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Search for ZH → ?+?-b$ar{b}$ is presented, using a Run 2 dataset with an integrated luminosity of 9.7 fb-1 collected by the DØ detector. Selected events contain at least two reconstructed jets and a Z candidate reconstructed with two opposite-sign charged muons. Random forests of decision trees are trained to distinguish between signal and background events in two orthogonal b-tag samples. The ZH → ?+?-b$ar{b}$b analysis is then combined with ZH → e+e-b$ar{b}$ analysis. For the combined results of ZH → l+l-b$ar{b}$b, no Higgs signal is observed, limits are set on the ZH cross-section BR(H→ b$ar{b}$) for different Higgs masses, from 90 to 150 GeV. For a Standard Model (SM) Higgs boson of mass 125 GeV, the observed cross-section limit is 7.1 times the SM cross-section with an expected sensitivity of 5.1 times the SM cross section. The result of ZH → l+l-b$ar{b}$b channel has been combined with searches in other Higgs decay channels at the Tevatron, which led to the first evidence of H → b$ar{b}$.

Download or read book A Search for the Standard Model Higgs Boson in the Process ZH u2192 L l b bar b in 4 1 Fb 1 of CDF II Data written by and published by . This book was released on 2010 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: The standard model of particle physics provides a detailed description of a universe in which all matter is composed of a small number of fundamental particles, which interact through the exchange of force - carrying gauge bosons (the photon, W ±, Z and gluons). The organization of the matter and energy in this universe is determined by the effects of three forces; the strong, weak, and electromagnetic. The weak and electromagnetic forces are the low energy manifestations of a single electro-weak force, while the strong force binds quarks into protons and neutrons. The standard model does not include gravity, as the effect of this force on fundamental particles is negligible. Four decades of experimental tests, spanning energies from a few electron-volts (eV) up to nearly two TeV, confirm that the universe described by the standard model is a reasonable approximation of our world. For example, experiments have confirmed the existence of the top quark, the W± and the Z bosons, as predicted by the standard model. The latest experimental averages for the masses of the top quark, W± and Z are respectively 173.1 ± 0.6(stat.) ± 1.1(syst.), 80.399 ± 0.023 and 91.1876 ± 0.0021 GeV/c2. The SM is a gauge field theory of zero mass particles. However, the SM is able to accommodate particles with non-zero mass through the introduction of a theoretical Higgs field which permeates all of space. Fermions gain mass through interactions with this field, while the longitudinal components of the massive W± and Z are the physical manifestations of the field itself. Introduction of the Higgs field, directly leads to the predicted existence of an additional particle, the Higgs boson. The Higgs boson is the only particle of the standard model that has not been observed, and is the only unconfirmed prediction of the theory. The standard model describes the properties of the Higgs boson in terms of its mass, which is a free parameter in the theory. Experimental evidence suggests that the Higgs mass has a value between 114.4 and 186 GeV/c2. Particles with a mass in this range can be produced in collisions of less massive particles accelerated to near the speed of light. Currently, one of only a few machines capable of achieving collision energies large enough to potentially produce a standard model Higgs boson is the Tevatron proton-antiproton collider located at Fermi National Accelerator Laboratory in Batavia, Illinois. This dissertation describes the effort to observe the standard model Higgs in Tevatron collisions recorded by the Collider Detector at Fermilab (CDF) II experiment in the ZH →l+l-b$ar{b}$ production and decay channel. In this process, the Higgs is produced along with a Z boson which decays to a pair of electrons or muons (Z →l+l-), while the Higgs decays to a bottom anti-bottom quark pair (H → b$ar{b}$). A brief overview of the standard model and Higgs theory is presented in Chapter 2. Chapter 3 explores previous searches for the standard model Higgs at the Tevatron and elsewhere. The search presented in this dissertation expands upon the techniques and methods developed in previous searches. The fourth chapter contains a description of the Tevatron collider and the CDF II detector. The scope of the discussion in Chapter 4 is limited to the experimental components relevant to the current ZH →l+l-b$ar{b}$ search. Chapter 5 presents the details of object reconstruction; the methods used to convert detector signals into potential electrons, muons or quarks. Chapter six describes the data sample studied for the presence of a ZH →l+l-b$ar{b}$ signal and details the techniques used to model the data. The model accounts for both signal and non-signal processes (backgrounds) which are expected to contribute to the observed event sample. Chapters 7 and 8 summarize the event selectio...

Download or read book Search for the Higgs Boson in the ZH u2192 v bar v b bar b Channel written by and published by . This book was released on 2010 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Standard Model of particle physics, the Higgs boson generates elementary particle masses. Current theoretical and experimental constraints lead to a Higgs boson mass between 114.4 and 158 GeV with 95% confidence level. Moreover, Tevatron has recently excluded the mass ranges between 100 and 109 GeV, 158 and 175 GeV with 95% confidence level. These results gives a clear indication to search for a Higgs boson at low mass. The D0 detector is located near Chicago, at the Tevatron, a proton-antiproton collider with an energy in the center of mass of 1.96 TeV. The topic of this thesis is the search for a Higgs boson in association with a Z boson. This channel is sensitive to low mass Higgs boson (135 GeV) which has a branching ratio H → bb varies between 50% and 90% in this mass range. The decay channel ZH → v$ar{v}$b$ar{b}$ studied has in the final state 2 heavy-flavor jets and some missing transverse energy due to escaping neutrinos. The heavy-flavor jets identification ('b-tagging') is done with a new algorithm (SLTNN) developed specifically for semi-leptonic decay of b quarks. The Higgs boson search analysis was performed with 3 fbsup-1

Download or read book Search for the Standard Model Higgs Boson in ZH u2192 V bar v b bar b Channel in P bar p Collisions at u221A s written by and published by . This book was released on 2011 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson is performed in 5.2 fb-1 of p$ar{p}$ collisions at p √s = 1.96 TeV, collected with the DØ detector at the Fermilab Tevatron. The final state considered is a pair of b jets with large missing transverse energy, as expected from p$ar{p}$→ ZH → v$ar{v}$b$ar{b}$ production. The search is also sensitive to the WH → lvb$ar{b}$ channel, where the charged lepton is not identified. Boosted decision trees are used to discriminate signal from background. Good agreement is observed between data and expected backgrounds, and, for a Higgs-boson mass of 115 GeV, a limit is set at 95% C.L. on the cross section multiplied by branching fraction of (p$ar{p}$ → (Z/W)H) × (H → b$ar{b}$) that is a factor 4.57 expected and 3.73 observed larger than the value expected from the standard model.

Download or read book Search for the Standard Model Higgs Boson in ZH 2 mu mu b bar b Production at D and Evidence for the H2 b bar b Decay at the Tevatron written by and published by . This book was released on 2014 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Search for ZH → [mu]+[mu]-b$\bar{b}$ is presented, using a Run 2 dataset with an integrated luminosity of 9.7 fb-1 collected by the DØ detector. Selected events contain at least two reconstructed jets and a Z candidate reconstructed with two opposite-sign charged muons. Random forests of decision trees are trained to distinguish between signal and background events in two orthogonal b-tag samples. The ZH → [mu]+[mu]-b$\bar{b}$b analysis is then combined with ZH → e+e-b$\bar{b}$ analysis. For the combined results of ZH → l+l-b$\bar{b}$b, no Higgs signal is observed, limits are set on the ZH cross-section BR(H→ b$\bar{b}$) for different Higgs masses, from 90 to 150 GeV. For a Standard Model (SM) Higgs boson of mass 125 GeV, the observed cross-section limit is 7.1 times the SM cross-section with an expected sensitivity of 5.1 times the SM cross section. The result of ZH → l+l-b$\bar{b}$b channel has been combined with searches in other Higgs decay channels at the Tevatron, which led to the first evidence of H → b$\bar{b}$.

Download or read book Search for the Standard Model Higgs Boson in the WH u2192 V B bar b Channel with the D0 Detector written by and published by . This book was released on 2009 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the Standard Model Higgs boson is performed in 4.0 fb-1 of p$ar{p}$ collisions at √s = 1.96 TeV, collected with the DØ detector at the Fermilab Tevatron. The final state considered is a pair of b-jets with large missing transverse energy and one hadronic tau decay as expected from the reaction p$ar{p}$ → WH → ? v b$ar{b}$. Boosted decision trees are used to discriminate the signal from the background. Good agreement is observed between data and expected backgrounds. For a Higgs boson mass of 115 GeV, a limit is set at 95% C.L. on the cross-section times branching fraction of (p$ar{p}$→ (Z/W)H)×(H → b$ar{b}$) which is 14 times larger than the Standard Model value.

Download or read book Search for the Higgs Boson in the ZH u2192 Vvb bar b Channel at CDF Run II written by and published by . This book was released on 2008 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This analysis focuses on a low mass Higgs boson search with 1.7 fb-1 of data. The focus is on Higgs events in which it is produced in association with a W or Z boson. Such events are expected to leave a distinct signature of large missing transverse energy for either a Z → vv decay or a leptonic W decay in which the lepton goes undetected, as well as jets with taggable secondary vertices from the H → b$ar{b}$ decay. Utilizing a new track based technique for removing QCD multi-jet processes as well as a neural network discriminant, an expected limit of 8.3 times the Standard Model prediction at the 95% CL for a Higgs boson mass of 115 GeV/c2 is calculated, with an observed limit of 8.0*SM.

Download or read book A Search for the Standard Model Higgs Boson in the Process ZH rightarrow ell ell B bar b in 4 1 unit fb 1 OF CDF II DATA written by and published by . This book was released on 2010 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: The standard model of particle physics provides a detailed description of a universe in which all matter is composed of a small number of fundamental particles, which interact through the exchange of force - carrying gauge bosons (the photon, W{sup ±}, Z and gluons). The organization of the matter and energy in this universe is determined by the effects of three forces; the strong, weak, and electromagnetic. The weak and electromagnetic forces are the low energy manifestations of a single electro-weak force, while the strong force binds quarks into protons and neutrons. The standard model does not include gravity, as the effect of this force on fundamental particles is negligible. Four decades of experimental tests, spanning energies from a few electron-volts (eV) up to nearly two TeV, confirm that the universe described by the standard model is a reasonable approximation of our world. For example, experiments have confirmed the existence of the top quark, the W{sup ±} and the Z bosons, as predicted by the standard model. The latest experimental averages for the masses of the top quark, W{sup ±} and Z are respectively 173.1 ± 0.6(stat.) {+-} 1.1(syst.), 80.399 {+-} 0.023 and 91.1876 {+-} 0.0021 GeV/c2. The SM is a gauge field theory of zero mass particles. However, the SM is able to accommodate particles with non-zero mass through the introduction of a theoretical Higgs field which permeates all of space. Fermions gain mass through interactions with this field, while the longitudinal components of the massive W{sup {+-}} and Z are the physical manifestations of the field itself. Introduction of the Higgs field, directly leads to the predicted existence of an additional particle, the Higgs boson. The Higgs boson is the only particle of the standard model that has not been observed, and is the only unconfirmed prediction of the theory. The standard model describes the properties of the Higgs boson in terms of its mass, which is a free parameter in the theory. Experimental evidence suggests that the Higgs mass has a value between 114.4 and 186 GeV/c2. Particles with a mass in this range can be produced in collisions of less massive particles accelerated to near the speed of light. Currently, one of only a few machines capable of achieving collision energies large enough to potentially produce a standard model Higgs boson is the Tevatron proton-antiproton collider located at Fermi National Accelerator Laboratory in Batavia, Illinois. This dissertation describes the effort to observe the standard model Higgs in Tevatron collisions recorded by the Collider Detector at Fermilab (CDF) II experiment in the ZH --> ll−b{bar b} production and decay channel. In this process, the Higgs is produced along with a Z boson which decays to a pair of electrons or muons (Z --> ll−), while the Higgs decays to a bottom anti-bottom quark pair (H --> b{bar b}). A brief overview of the standard model and Higgs theory is presented in Chapter 2. Chapter 3 explores previous searches for the standard model Higgs at the Tevatron and elsewhere. The search presented in this dissertation expands upon the techniques and methods developed in previous searches. The fourth chapter contains a description of the Tevatron collider and the CDF II detector. The scope of the discussion in Chapter 4 is limited to the experimental components relevant to the current ZH --> l+l−b{bar b} search. Chapter 5 presents the details of object reconstruction; the methods used to convert detector signals into potential electrons, muons or quarks. Chapter six describes the data sample studied for the presence of a ZH --> l+l−b{bar b} signal and details the techniques used to model the data. The model accounts for both signal and non-signal processes (backgrounds) which are expected to contribute to the observed event sample. Chapters 7 and 8 summarize the event selection applied to isolate ZH --> l+l−b{bar b} candidate events from the data sample, and the advanced techniques employed to maximize the separation of the signal from background processes. Chapters 9 and 10 present the systematic uncertainties affecting our modeling of the data sample and the results of the search. Chapter 11 presents a discussion of ZH --> l+l−b{bar b} in the context of the overall Tevatron efforts to observe a standard model Higgs signal.

Download or read book Search for the Standard Model Higgs Boson in P bar p Interactions with the Decay Mode H u2192 W W u2192 v v at the D Experiment written by and published by . This book was released on 2010 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: A search for the standard model Higgs boson in p$ar{p}$ collisions resulting in two muons and large missing transverse energy is presented. The analysis uses 4.2 fb-1 of integrated luminosity at a center-of-mass energy of √s = 1.96 TeV collected between April 2002 and December 2008 with the D0 detector at the Fermilab Tevatron collider. No significant excess above the background estimation is observed and limits are derived on Higgs boson production.

Download or read book Search for the Standard Model Higgs Boson in the P Anti p ZH Nu Anti nu B Anti b Channel written by and published by . This book was released on 2006 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report a search for the standard model (SM) Higgs boson based on data collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 260 pb−1. We study events with missing transverse energy and two acoplanar b-jets, which provide sensitivity to the ZH production cross section in the [nu]{bar [nu]}B{bar b} channel and to WH production, when the lepton from the W → l{nu} decay is undetected. The data are consistent with the SM background expectation, and we set 95% C.L. upper limits on [sigma](p{bar p} → ZN/WH) x B(H → b{bar b}) from 3.4/8.3 to 2.5/6.3 pb, for Higgs masses between 105 and 135 GeV.

Download or read book A Search for the Higgs Boson in the ZH Dilepton Decay Channel at CDF II written by and published by . This book was released on 2009 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes a search for the Standard Model Higgs boson produced in association with the Z boson via Higgs-strahlung at the CDF II detector at the Tevatron. At a Higgs boson mass between 100 GeV/c2 and 135 GeV/c2, the primary Higgs decay mode is to a pair of b quarks. The associated Z boson can decay to a pair of electrons or muons, allowing detection of a final event signature of two visible leptons and two b quarks. This final state allows reduction of large QCD backgrounds compared to a hadronic Z boson decay, leading to a more sensitive search. To increase sensitivity, standard model matrix element probabilities for ZH signal and the dominant backgrounds are used as components to a likelihood fit in signal fraction. In 2.7 fb−1 of CDF II data, we see no evidence of production of a Higgs boson with a mass between 100 GeV c2 and 150 GeV/c2. Using the Feldman-Cousins technique to set a limit, at 95% coverage and a Higgs boson mass of 115 GeV/c2, the median expected limit was 12.1 x [sigma]{sub SM} and a limit of 8.2 x [sigma]{sub SM} was observed, where [sigma]{sub SM} is the NNLO theoretical cross section of p{bar p} →ZH → l +l -b{bar b} at √s=1.96 TeV . Cross section limits are computed at a range of Higgs boson mass values between 100 GeV/c 2 and 150 GeV/c2.

Download or read book Higgs Decay to Bottom Quarks at the Tevatron written by and published by . This book was released on 1993 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: We study the production and detection of the standard-model Higgs boson at the Fermilab Tevatron. The most promising mode is WH and ZH associated production followed by leptonic decay of the weak vector bosons and H --> b{bar b}. It may be possible to detect a Higgs boson of mass m{sub H} = 60--80 GeV with 1000 pb−1 of integrated luminosity.

Download or read book Search for the Standard Model Higgs Boson in the Decay Mode H u2192 W W u2192 L vl v written by and published by . This book was released on 2009 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The question of the nature and principles of the universe and our place in it is the driving force of science since Mesopotamian astronomers glanced for the first time at the starry sky and Greek atomism has been formulated. During the last hundred years modern science was able to extend its knowledge tremendously, answering many questions, opening entirely new fields but as well raising many new questions. Particularly Astronomy, Astroparticle Physics and Particle Physics lead the race to answer these fundamental and ancient questions experimentally. Today it is known that matter consists of fermions, the quarks and leptons. Four fundamental forces are acting between these particles, the electromagnetic, the strong, the weak and the gravitational force. These forces are mediated by particles called bosons. Our confirmed knowledge of particle physics is based on these particles and the theory describing their dynamics, the Standard Model of Particles. Many experimental measurements show an excellent agreement between observation and theory but the origin of the particle masses and therefore the electroweak symmetry breaking remains unexplained. The mechanism proposed to solve this issue involves the introduction of a complex doublet of scalar fields which generates the masses of elementary particles via their mutual interactions. This Higgs mechanism also gives rise to a single neutral scalar boson with an unpredicted mass, the Higgs boson. During the last twenty years several experiments have searched for the Higgs boson but so far it escaped direct observation. Nevertheless these studies allow to further constrain its mass range. The last experimental limits on the Higgs mass have been set in 2001 at the LEP collider, an electron positron machine close to Geneva, Switzerland. The lower limit set on the Higgs boson mass is mH > 114.4 GeV/c2 and remained for many years the last experimental constraint on the Standard Model Higgs Boson due to the shutdown of the LEP collider and the experimental challenges at hadron machines as the Tevatron. This thesis was performed using data from the D0 detector located at the Fermi National Accelerator Laboratory in Batavia, IL. Final states containing two electrons or a muon and a tau in combination with missing transverse energy were studied to search for the Standard Model Higgs boson, utilizing up to 4.2 fb-1 of integrated luminosity. In 2008 the CDF and D0 experiments in a combined effort were able to reach for the first time at a hadron collider the sensitivity to further constrain the possible Standard Model Higgs boson mass range. The research conducted for this thesis played a pivotal role in this effort. Improved methods for lepton identification, background separation, assessment of systematic uncertainties and new decay channels have been studied, developed and utilized. Along with similar efforts at the CDF experiment these improvements led finally the important result of excluding the presence of a Standard Model Higgs boson in a mass range of mH = 160-170 GeV/c2 at 95% Confidence Level. Many of the challenges and methods found in the present analysis will probably in a similar way be ingredients of a Higgs boson evidence or discovery in the near future, either at the Tevatron or more likely at the soon starting Large Hadron Collider (LHC). Continuing to pursue the Higgs boson we are looking forward to many exciting results at the Tevatron and soon at the LHC. In Chapter 2 an introduction to the Standard Model of particle physics and the Higgs mechanism is given, followed by a brief outline of existing theoretical and experimental constraints on the Higgs boson mass before summarizing the Higgs boson production modes. Chapter 3 gives an overview of the experimental setup. This is followed by a description of the reconstruction of the objects produced in proton-antiproton collisions in Chapter 4 and the necessary calorim...

Download or read book A Search for the Higgs Boson in the Zh Channel with the D0 Detector at the Fermilab Tevatron Collider written by James Matthew Heinmiller and published by . This book was released on 2006 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This analysis describes a search for a standard model Higgs boson produced in association with a Z boson through the decay mode ZH {yields} e{sup +}e{sup -}b{bar b} in p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron Collider. The data sample used in this analysis corresponds to 452 pb{sup -1} of integrated luminosity accumulated with the D{null} detector. Agreement between data and standard model predictions is observed. A 95% confidence level upper exclusion limit for the {sigma}(p{bar p} {yields} ZH) x BR(H {yields} b{bar b}) channel is set between 3.2-8.2 pb for Higgs masses of 105 to 145 GeV.

Download or read book The Search for VH u2192 VWW Standard Model Higgs Production in the Trilepton Signature with 5 9fb 1 of Data from P bar p Collisions at u221A s written by and published by . This book was released on 2010 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present here the search for Standard Model V H → VWW → lll + ET (missing energy due to neutrinos) production, where V is a W or Z weak vector boson, which uses up to 5.9 fb-1 of integrated luminosity. This analysis has recently added to the CDF high-mass Higgs group three new signal topologies characterized by a tri-lepton signature, which are chosen to isolate the V H → VWW associated production signals in the three-lepton signature. As such, we define three new regions for a WH analysis, a ZH 1-jet analysis, and a ZH ≥ 2-jet analysis with which we expect to contribute an additional 5.8% (for mH = 165 GeV) acceptance to the current H → WW dilepton analysis. The ZH trilepton regions are defined by events passing a Z-boson selection: events having at least one lepton pairing (among three possible pairings) with opposite sign, same flavor, and a dilepton invariant mass within [76.0, 106.0] GeV–a ± 15 GeV window around the Z-boson mass. TheWH trilepton region is then defined as the set of trilepton events that are complement to those chosen by the Z-boson selection. These three new event topologies make a substantial contribution to the H → WW group result. As a measure of the sensitivity of this search, we compute the median expected limit on the at 95% confidence level (?C.L.?) on the production cross section (effectively the rate of production) for a StandardModel Higgs boson and report the result as a ratio to the theoretical production cross section. An observed limit ratio of one or less at a given mass would rule out the production of a Standard Model Higgs boson at that mass with 95% confidence. At mH = 165 GeV, the WH analysis expected limits reach 7.2 times the standard model cross section; the ZH 1-jet analysis is set at 29 times the expected standard model cross section; the ZH ≥ 2-jet analysis is set at 9.9 times the expected standard model cross section; and the combined trilepton analysis is set at 4.9 times the expected standard model cross section. We announce that the combination of this trilepton V H → VWW Higgs boson search and the previous CDF dilepton H → WW search achieves an expected median limit of 1.00 at 165 GeV/c2. The expected median limit of 1.00 indicates we anticipate a 50% probability of ruling out the existence of a Standard Model Higgs boson with a mass of 165 GeV/c2. This is the first time a single hadron collider experiment has achieved sensitivity to the production of a Standard Model Higgs boson. We do not see evidence for a significant signal of Higgs bosons in the data and place observed limits on the production of a Standard Model Higgs boson of 165 GeV/c2 at 1.08 times Standard Model production cross section. Matthew.

Download or read book First Search for the Standard Model Higgs Boson Using the Semileptonic Decay Channel written by and published by . This book was released on 2010 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents the first search for the standard model Higgs boson (H) in decay topologies containing a muon, an imbalance in transverse momentum (ET) and jets, using p$ar{p}$ collisions at √s = 1.96 TeV with an integrated luminosity of 4.3 fb-1 recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primary to contributions from Higgs bosons produced through gluon fusion, with subsequent decay H → WW → ??jj where W represents a real or virtual W boson. In the absence of signal, limits are set at 95% confidence on the production and decay of the standard model Higgs boson for MH in the range of 115-200 GeV. For MH = 165 GeV, the observed and expected limits are factors of 11.2 larger than the standard model value. Combining this channel with e?jj final states and including earlier data to increase the integrated luminosity to 5.4 fb-1 produces observed(expected) limits of 5.5(3.8) times the standard model value.

Download or read book Search for the Standard Model Higgs Boson in Z H Nu Anti nu B Anti b Channel at written by and published by . This book was released on 2009 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 √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 → [nu]{anti {nu}} branching ratio, but also has many experimental challenges due to the large multijet background and the absence of visible carged leptons in the final state. We present the result with 5.2 fb−1 of data and discuss the recent improvements in the sensitivity.