Search for Pair Production of Scalar Top Quarks Decaying to a Tau Lepton and a B Quark in Ppbar Collisions at Sqrt{s}

Search for Pair Production of Scalar Top Quarks Decaying to a Tau Lepton and a B Quark in Ppbar Collisions at Sqrt{s} PDF Author:
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Languages : en
Pages : 8

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Book Description
We present the results of a search for pair production of scalar top quarks ({tilde t}1) in an R-parity violating supersymmetric scenario using 322 pb−1 of p{bar p} collisions at √s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. We assume each {tilde t}1 decays into a? lepton and a b quark with a branching ratio?, and that the final state contains either an electron or a muon from a leptonic? decay, a hadronically decaying? lepton, and two or more jets. Two candidate events pass our final selection criteria, consistent with the expectation from standard model processes. We present upper limits on the cross section times branching ratio squared?({tilde t}1{bar {tilde t}}1) x?2 as a function of the stop mass m({tilde t}1). Assuming? = 1, we set a 95% confidence level limit m({tilde t}1)> 153 GeV=c2 obtained using a next-to-leading order cross section. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark decaying into a? lepton and a b quark.

Search for Pair Production of Scalar Top Quarks Decaying to a Tau Lepton and a B Quark in Ppbar Collisions at Sqrt{s}

Search for Pair Production of Scalar Top Quarks Decaying to a Tau Lepton and a B Quark in Ppbar Collisions at Sqrt{s} PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8

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Book Description
We present the results of a search for pair production of scalar top quarks ({tilde t}1) in an R-parity violating supersymmetric scenario using 322 pb−1 of p{bar p} collisions at √s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. We assume each {tilde t}1 decays into a? lepton and a b quark with a branching ratio?, and that the final state contains either an electron or a muon from a leptonic? decay, a hadronically decaying? lepton, and two or more jets. Two candidate events pass our final selection criteria, consistent with the expectation from standard model processes. We present upper limits on the cross section times branching ratio squared?({tilde t}1{bar {tilde t}}1) x?2 as a function of the stop mass m({tilde t}1). Assuming? = 1, we set a 95% confidence level limit m({tilde t}1)> 153 GeV=c2 obtained using a next-to-leading order cross section. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark decaying into a? lepton and a b quark.

Search for Pair Production of Scalar Top Quarks Decaying to A? Lepton and a B Quark in 1.96 TeV P$\bar{p}$ Collisions

Search for Pair Production of Scalar Top Quarks Decaying to A? Lepton and a B Quark in 1.96 TeV P$\bar{p}$ Collisions PDF Author:
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ISBN:
Category :
Languages : en
Pages : 190

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Book Description
I present the results of a search for pair production of scalar top quarks ($ ilde{t}$1) in an R-parity violating supersymmetric scenario using 322 pb-1 of p{bar p} collisions at √s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each $ ilde{t}$1 decays into a ? lepton and a b quark, with branching ratio ?, and search for final states containing either an electron or a muon from a leptonic ? decay, a hadronically decaying ? lepton, and two or more jets. Two candidate events pass my final selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared ?($ ilde{t}$1$ ilde{t}$1) x ?2 as a function of the stop mass m($ ilde{t}$1). Assuming ? = 1, I set a 95% confidence level limit m($ ilde{t}$1) > 153 GeV=c2. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a ? lepton and a b quark.

Search for Pair Production of Scalar Top Quarks Decaying to a [tau] Lepton and a [beta] Quark in 1.96-tev Pp Collisions

Search for Pair Production of Scalar Top Quarks Decaying to a [tau] Lepton and a [beta] Quark in 1.96-tev Pp Collisions PDF Author: Vadim Gennadyevich Khotilovich
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Languages : en
Pages :

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Book Description
I present the results of a search for pair production of scalar top quarks (t̃1) in an R-parity violating supersymmetric scenario using 322 pb−1 of pp collisions at [square root]s = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each t̃1 decays into a [tau] lepton and a [beta] quark, with branching ratio [beta], and search for nal states containing either an electron or a muon from a leptonic [tau] decay, a hadronically decaying [tau] lepton, and two or more jets. Two candidate events pass my nal selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared [sigma](t̃1t̃1) X [beta]2 as a function of the stop mass (mt̃1). Assuming [beta]= 1, I set a 95% condence level limit m(t̃1)> 153 GeV=c2. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a [tau] lepton and a [beta] quark.

Search for Pair Production of Third-generation Scalar Leptoquarks and Top Squarks in Proton-proton Collisions at [arrow]"

Search for Pair Production of Third-generation Scalar Leptoquarks and Top Squarks in Proton-proton Collisions at [arrow] Author:
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ISBN:
Category :
Languages : en
Pages : 21

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Book Description
A search for pair production of third-generation scalar leptoquarks and supersymmetric top quark partners, top squarks, in final states involving tau leptons and bottom quarks is presented. The search uses events from a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.7 fb-1, collected with the CMS detector at the LHC with [arrow]" = 8 TeV. The number of observed events is found to be in agreement with the expected standard model background. Third-generation scalar leptoquarks with masses below 740 GeV are excluded at 95% confidence level, assuming a 100% branching fraction for the leptoquark decay to a tau lepton and a bottom quark. In addition, this mass limit applies directly to top squarks decaying via an R-parity violating coupling [lambda]'333. The search also considers a similar signature from top squarks undergoing a chargino-mediated decay involving the R-parity violating coupling [lambda]'3jk. Each top squark decays to a tau lepton, a bottom quark, and two light quarks. Top squarks in this model with masses below 580 GeV are excluded at 95% confidence level. The constraint on the leptoquark mass is the most stringent to date, and this is the first search for top squarks decaying via [lambda]'3jk.

Search for Pair Production of the Scalar Top Quark in the Electron+muon Final State

Search for Pair Production of the Scalar Top Quark in the Electron+muon Final State PDF Author:
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Category :
Languages : en
Pages : 8

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Book Description
We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ({tilde t}1) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb−1. The scalar top quarks are assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}), and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and improved exclusion limits at the 95% C.L. are set in the (M{sub {tilde t}1}, M{sub {tilde {nu}}}) mass plane.

Search for Direct Scalar Top Pair Production in Final States with Two Tau Leptons in Pp Collisions at √ S

Search for Direct Scalar Top Pair Production in Final States with Two Tau Leptons in Pp Collisions at √ S PDF Author: Ewan Chin Hill
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Languages : en
Pages :

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Book Description
The ATLAS Experiment at the CERN Large Hadron Collider is a particle physics experiment to study fundamental particles and their interactions at very high energies. Supersymmetry is a theory of new physics beyond the Standard Model of particle physics. A search for directly produced pairs of the supersymmetric partner of the top quark was performed using 20 fb^-1 of proton--proton collision data at a centre of mass energy of 8 TeV taken in 2012. The search targeted a model where the supersymmetric partner of the top quark (``scalar top'') decays via the supersymmetric partner of the tau lepton (``scalar tau'') into the supersymmetric partner of the graviton (``gravitino''). Scalar top candidates were searched for in pp collision events with either two hadronically decaying taus, two light leptons (electrons or muons), or one hadronically decaying tau and one light lepton. The numbers of events passing the analysis selection criteria agree with the Standard Model expectations. Exclusion limits at the 95% confidence level were set as a function of the scalar top and scalar tau masses. Depending on the scalar tau mass, ranging from the 87 GeV limit set by the LEP experiments to a few GeV below the scalar top mass, lower limits between 490 GeV and 640 GeV were placed on the scalar top mass within the model considered.

Search for Direct Pair Production of Supersymmetric Top Quarks Decaying to All-hadronic Final States in Pp Collisions at {u221A}s

Search for Direct Pair Production of Supersymmetric Top Quarks Decaying to All-hadronic Final States in Pp Collisions at {u221A}s PDF Author:
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Languages : en
Pages : 46

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Book Description
Here, results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9 fb–1 of proton-proton collisions at a centre-of-mass energy of 8 TeV produced by the LHC. The search features novel background suppression and prediction methods, including a dedicated top quark pair reconstruction algorithm. The data are found to be in agreement with the predicted backgrounds. Exclusion limits are set in simplified supersymmetry models with the top squark decaying to jets and an undetected neutralino, either via a top quark or through a bottom quark and chargino. Models with the top squark decaying via a top quark are excluded for top squark masses up to 755 GeV in the case of neutralino masses below 200 GeV. For decays via a chargino, top squark masses up to 620 GeV are excluded, depending on the masses of the chargino and neutralino.

Search for Third-Generation Scalar Leptoquarks in the T$\tau$ Channel in Proton-Proton Collisions at $\sqrt{s}$

Search for Third-Generation Scalar Leptoquarks in the T$\tau$ Channel in Proton-Proton Collisions at $\sqrt{s}$ PDF Author:
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ISBN:
Category :
Languages : en
Pages : 41

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Book Description
A search for pair production of third-generation scalar leptoquarks decaying to top quark and $\tau$ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of $\sqrt{s}$ = 8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb-1. The search is performed using events that contain an electron or a muon, a hadronically decaying $\tau$ lepton, and two or more jets. The observations are found to be consistent with the standard model predictions. Assuming that all leptoquarks decay to a top quark and a $\tau$ lepton, the existence of pair produced, charge -1/3, third-generation leptoquarks up to a mass of 685 GeV is excluded at 95% confidence level. This result constitutes the first direct limit for leptoquarks decaying into a top quark and a $\tau$ lepton, and may also be applied directly to the pair production of bottom squarks decaying predominantly via the R-parity violating coupling [lambda]' 333.

Search for Direct Pair Production of Scalar Top Quarks in the Single- and Dilepton Channels in Proton-proton Collisions at $\sqrt{s}$

Search for Direct Pair Production of Scalar Top Quarks in the Single- and Dilepton Channels in Proton-proton Collisions at $\sqrt{s}$ PDF Author:
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Languages : en
Pages :

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Book Description
Results are reported from a search for the top squark $ \tilde{t}_1 $, the lighter of the two supersymmetric partners of the top quark. The data sample corresponds to 19.7 fb$^{-1}$ of proton-proton collisions at $\sqrt{s} =$ 8 TeV collected with the CMS detector at the LHC. The search targets $ \tilde{t}_1 \to \mathrm{b} \tilde{\chi}^{\pm}_1$ and $ \tilde{t}_1 \to \mathrm{t}^{(*)} \tilde{\chi}^0_1$ decay modes, where $\tilde{\chi}^{\pm}_1$ and $\tilde{\chi}^0_1$ are the lightest chargino and neutralino, respectively. The reconstructed final state consists of jets, b jets, missing transverse energy, and either one or two leptons. Leading backgrounds are determined from data. No significant excess in data is observed above the expectation from standard model processes. The results exclude a region of the two-dimensional plane of possible $ \tilde{t}_1 $ and $\tilde{\chi}^0_1 $ masses. The highest excluded $ \tilde{t}_1 $ and $ \tilde{\chi}^0_1$ masses are about 700 GeV and 250 GeV, respectively.

Measurement of the Top Anti-top Quark Pair Production Cross Section in the Dilepton Decay Channel Using Lepton+Track Selection in 7 TeV P - P Collisions with L

Measurement of the Top Anti-top Quark Pair Production Cross Section in the Dilepton Decay Channel Using Lepton+Track Selection in 7 TeV P - P Collisions with L PDF Author:
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Category :
Languages : en
Pages :

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Book Description