Strange Particle Production in Pp Collisions at Sqrt(s)

Strange Particle Production in Pp Collisions at Sqrt(s)
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Total Pages : 38
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ISBN-10 : OCLC:1066581936
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Rating : 4/5 (36 Downloads)

Synopsis Strange Particle Production in Pp Collisions at Sqrt(s) by :

The spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7 TeV. The K0_s, Lambda, and Xi-̂ particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum. The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The transverse momentum distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.

Measurement of Neutral Strange Particle Production in the Underlying Event in Proton-proton Collisions at Sqrt(s)

Measurement of Neutral Strange Particle Production in the Underlying Event in Proton-proton Collisions at Sqrt(s)
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Total Pages : 35
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ISBN-10 : OCLC:1066366540
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Rating : 4/5 (40 Downloads)

Synopsis Measurement of Neutral Strange Particle Production in the Underlying Event in Proton-proton Collisions at Sqrt(s) by :

Measurements are presented of the production of primary K(S)0 and Lambda particles in proton-proton collisions at sqrt(s) = 7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar transverse momentum sum of K(S)0 and Lambda particles measured at pseudorapidities abs(eta)

Search for New Phenomena in Three- Or Four-lepton Events in Pp Collisions at [square Root]s

Search for New Phenomena in Three- Or Four-lepton Events in Pp Collisions at [square Root]s
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Total Pages : 0
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ISBN-10 : OCLC:1374980763
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Rating : 4/5 (63 Downloads)

Synopsis Search for New Phenomena in Three- Or Four-lepton Events in Pp Collisions at [square Root]s by : [Study Group] ATLAS Collaboration CERN

Abstract: A search with minimal model dependence for physics beyond the Standard Model in events featuring three or four charged leptons (3l and 4l, ) is presented. The analysis aims to be sensitive to a wide range of potential new-physics theories simultaneously. This analysis uses data from pp collisions delivered by the Large Hadron Collider at a centre-of-mass energy of TeV and recorded with the ATLAS detector, corresponding to the full Run 2 dataset of 139 fb−1. The 3l and 4l phase space is divided into 22 event categories according to the number of leptons in the event, the missing transverse momentum, the invariant mass of the leptons, and the presence of leptons originating from a Z-boson candidate. These event categories are analysed independently for the presence of deviations from the Standard Model. No statistically significant deviations from the Standard Model predictions are observed. Upper limits for all signal regions are reported in terms of the visible cross-section

Charged Particle Transverse Momentum Spectra in Pp Collisions at Sqrt(s)

Charged Particle Transverse Momentum Spectra in Pp Collisions at Sqrt(s)
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Total Pages : 36
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ISBN-10 : OCLC:1066604416
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Rating : 4/5 (16 Downloads)

Synopsis Charged Particle Transverse Momentum Spectra in Pp Collisions at Sqrt(s) by :

The charged particle transverse momentum (pT) spectra are presented for pp collisions at sqrt(s)=0.9 and 7 TeV. The data samples were collected with the CMS detector at the LHC and correspond to integrated luminosities of 231 inverse microbarns and 2.96 inverse picobarns, respectively. Calorimeter-based high-transverse-energy triggers are employed to enhance the statistical reach of the high-pT measurements. The results are compared with both leading-order QCD and with an empirical scaling of measurements at different collision energies using the scaling variable xT = 2 pT/sqrt(s) over the pT range up to 200 GeV/c. Using a combination of xT scaling and direct interpolation at fixed pT, a reference transverse momentum spectrum at sqrt(s)=2.76 TeV is constructed, which can be used for studying high-pT particle suppression in the dense QCD medium produced in heavy-ion collisions at that centre-of-mass energy.

Strange Particle Production in $p+p$ Collisions at $\sqrt{s}$

Strange Particle Production in $p+p$ Collisions at $\sqrt{s}$
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ISBN-10 : OCLC:727211201
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Rating : 4/5 (01 Downloads)

Synopsis Strange Particle Production in $p+p$ Collisions at $\sqrt{s}$ by :

We present strange particle spectra and yields measured atmid-rapidity in sqrt text s=200 GeV proton-proton (p+p) collisions atRHIC. We find that the previously observed universal transverse mass(mathrm mT \equiv\sqrt mathrm p_T 2+\mathrm m2) scaling of hadronproduction in p+p collisions seems to break down at higher \mt and thatthere is a difference in the shape of the \mt spectrum between baryonsand mesons. We observe mid-rapidity anti-baryon to baryon ratios nearunity for Lambda and Xi baryons and no dependence of the ratio ontransverse momentum, indicating that our data do not yet reach thequark-jet dominated region. We show the dependence of the mean transversemomentum (\mpt) on measured charged particle multiplicity and on particlemass and infer that these trends are consistent with gluon-jet dominatedparticle production. The data are compared to previous measurements fromCERN-SPS, ISR and FNAL experiments and to Leading Order (LO) and Next toLeading order (NLO) string fragmentation model predictions. We infer fromthese comparisons that the spectral shapes and particle yields from $p+p$collisions at RHIC energies have large contributions from gluon jetsrather than quark jets.

A Search for New Phenomena in Pp Collisions at $\sqrt{s}$

A Search for New Phenomena in Pp Collisions at $\sqrt{s}$
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ISBN-10 : OCLC:967921214
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Rating : 4/5 (14 Downloads)

Synopsis A Search for New Phenomena in Pp Collisions at $\sqrt{s}$ by :

A search for new phenomena is performed in final states containing one or more jets and an imbalance in transverse momentum in pp collisions at a centre-of-mass energy of 13 TeV. The analysed data sample, recorded with the CMS detector at the CERN LHC, corresponds to an integrated luminosity of 2.3 inverse femtobarns. Several kinematic variables are employed to suppress the dominant background, multijet production, as well as to discriminate between other standard model and new physics processes. The search provides sensitivity to a broad range of new-physics models that yield a stable weakly interacting massive particle. The number of observed candidate events is found to agree with the expected contributions from standard model processes, and the result is interpreted in the mass parameter space of fourteen simplified supersymmetric models that assume the pair production of gluinos or squarks and a range of decay modes. For models that assume gluino pair production, masses up to 1575 and 975 GeV are excluded for gluinos and neutralinos, respectively. For models involving the pair production of top squarks and compressed mass spectra, top squark masses up to 400 GeV are excluded.