968 research outputs found
Measurement of WZ and ZZ production in pp collisions at √s = 8 TeV in final states with b-tagged jets
No full textOpen Access This article is distributed under the terms of the Creative
Commons Attribution License which permits any use, distribution, and
reproduction in any medium, provided the original author(s) and the
source are credited.
Funded by SCOAP3 / License Version CC BY 4.0.Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at s √ =8 TeV in final states where one Z boson decays to b-tagged jets. The other gauge boson, either W or Z, is detected through its leptonic decay (either W→eν , μν or Z→e + e − , μ + μ − , or νν ¯ ). The results are based on data corresponding to an integrated luminosity of 18.9 fb −1 collected with the CMS detector at the Large Hadron Collider. The measured cross sections, σ(pp→WZ)=30.7±9.3(stat.)±7.1(syst.)±4.1(th.)±1.0(lum.)pb and σ(pp→ZZ)=6.5±1.7(stat.)±1.0(syst.)±0.9(th.)±0.2(lum.)pb , are consistent with next-to-leading order quantum chromodynamics calculationsBMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil);
MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CS (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF(Germany);GSRT(Greece);OTKAand NIH(Hungary);DAEand DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania);MOE and UM(Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland);
NSC (Taipei); ThEPCenter, IPST, STAR and NSTDA(Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA)
Partial Dissociation and Hydration Quantitatively Explain the Properties of Aqueous Electrolyte Solutions and hence Empirical Activity Concepts are Unnecessary
No full textThe author shows that Arrhenius's theory of partial electrolytic dissociation was immaturely displaced about eight decades ago by the empirical concept of ionic activities and the assumption of complete dissociation of electrolytes at all concentrations. The latter brought the theory of electrolytes over the next decades into a complicated state without any physical significance. Therefore, the author started a systematic investigation of the available data and could completely restore the original theory of partial dissociation. Now solution properties can be easily understood and quantitatively explained in terms of absolute concentrations and volumes of ions and ion pairs and hydration
Diffractive W and Z production at the Fermilab Tevatron
No full textWe report on a measurement of the fraction of events with a W or Z boson which are produced diffractively in p̅ p collisions at √s=1.96 [square root of s = 1.96] TeV, using data from 0.6 fb-1 [fb superscript -1] of integrated luminosity collected with the CDF II detector equipped with a Roman-pot spectrometer that detects the p̅ from p̅ +p→p̅ +[X+W/Z]. We find that (1.00±0.11)% of Ws and (0.88±0.22)% of Zs are produced diffractively in a region of antiproton or proton fractional momentum loss ξ [xi] of 0.03<ξ<0.10 [0.03 < xi <0.10] and 4-momentum transferred squared t of -1<t<0 (GeV/c)2 [(GeV/c) superscript 2], where we account for the events in which the proton scatters diffractively while the antiproton dissociates, p̅ +p→[X+W/Z]+p, by doubling the measured proton dissociation fraction. We also report on searches for W and Z production in double Pomeron exchange, p+p̅ →p+[X+W/Z]+p̅ , and on exclusive Z production, p̅ +p→p̅ +Z+p. No signal is seen above background for these processes, and comparisons are made with expectations.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
Search for hadronic decays of W and Z bosons in photon events in p(p)over-bar collisions at root s = 1.96 TeV (vol 80, 052011, 2009)
No full textWe report on a search for the process p anti-p --> gamma + W/Z with W/Z --> qq-bar in events containing two jets and a photon at the center-of-mass energy s**(1/2) = 1.96 TeV, using 184 pb-1 of data collected by the CDF II detector. A neural network event selection has been developed to optimize the rejection of the large QCD production background; it is shown that this method gives a significant improvement in both signal-to-noise ratio and signal sensitivity, as compared with an event selection based on conventional cuts. An upper limit is presented for the gamma + W/Z production cross section with the W and Z decaying hadronically
Search for hadronic decays of W and Z bosons in photon events in pp̅ collisions at √s=1.96 TeV
No full textWe report on a search for the process pp̅ →γ+W/Z with W/Z→qq̅ in events containing two jets and a photon at the center-of-mass energy √s=1.96 TeV, using 184 pb[superscript -1] of data collected by the CDF II detector. A neural network event selection has been developed to optimize the rejection of the large QCD production background; it is shown that this method gives a significant improvement in both signal-to-noise ratio and signal sensitivity, as compared with an event selection based on conventional cuts. An upper limit is presented for the γ+W/Z production cross section with the W and Z decaying hadronically.Academy of FinlandSlovak R&D AgencyPrograma Consolider-Ingenio 2010, SpainMinisterio de Ciencia e Innovación, SpainRussian Foundation for Basic ResearchInstitut National de Physique Nucleaire et Physique des Particules/CNRSRoyal Society, United KingdomScience and Technology Facilities Council, United KingdomKorean Research FoundationKorean Science and Engineering FoundationBundesministerium für Bildung und Forschung, GermanyAlfred P. Sloan FoundationSwiss National Science FoundationNational Science Council of the Republic of ChinaNatural Sciences and Engineering Research Council of CanadaMinistry of Education, Culture, Sports, Science and Technology of JapanItalian Istituto Nazionale di Fisica NucleareNational Science FoundationUnited States Department of Energ
Measurement of differential production cross sections for Z /γ∗ bosons in association with jets in p p ̄ collisions at √s =1.96TeV
No full textDifferential cross sections for the production of Z bosons or off-shell photons gamma* in association with jets are measured in proton-antiproton collisions at center-of-mass energy √s = 1.96 TeV using the full data set collected with the Collider Detector at Fermilab in Tevatron run II and corresponding to 9.6 fb(-1) of integrated luminosity. Results include first measurements at CDF of differential cross sections in events with a Z/gamma* boson and three or more jets, the inclusive cross section for production of Z/gamma* and four or more jets, and cross sections as functions of various angular observables in lower jet-multiplicity final states. Measured cross sections are compared to several theoretical predictions
First Measurement of the Angular Coefficients of Drell-Yan e(+)e(-) Pairs in the Z Mass Region from p(p)over-bar Collisions at root s=1.96 TeV
No full textWe report on the first measurement of the angular distributions of final state electrons in p (p) over bar -> gamma*/Z -> e(+)e(-) + X events produced in the Z boson mass region at root s = 1.96 TeV. The data sample collected by the CDF II detector for this result corresponds to 2.1 fb(-1) of integrated luminosity. The angular distributions are studied as a function of the transverse momentum of the electron-positron pair and show good agreement with the Lam-Tung relation, consistent with a spin-1 description of the gluon, and demonstrate that, at high values of the transverse momentum, Z bosons are produced via quark-antiquark annihilation and quark-gluon Compton processes
First Search for Exotic Z Boson Decays into Photons and Neutral Pions in Hadron Collisions
No full textA search for forbidden and exotic Z boson decays in the diphoton mass spectrum is presented for the first time in hadron collisions, based on data corresponding to 10.0 fb−1 of integrated luminosity from proton-antiproton collisions at √s=1.96 TeV collected by the CDF experiment. No evidence of signal is observed, and 95% credibility level Bayesian upper limits are set on the branching ratios of decays of the Z boson to a photon and neutral pion (which is detected as a photon), a pair of photons, and a pair of neutral pions. The observed branching ratio limits are 2.01×10−5 for Z→π0γ, 1.46×10−5 for Z→γγ, and 1.52×10−5 for Z→π0π0. The Z→π0γ and Z→γγ limits improve the most stringent results from other experiments by factors of 2.6 and 3.6, respectively. The Z→π0π0 branching ratio limit is the first experimental result on this decay
Probing color coherence effects in pp collisions at √s = 7 TeV
No full textOpen Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the
source are credited. Funded by SCOAP3 / License Version CC BY 4.0.A study of color coherence effects in pp collisions at a center-of-mass energy of 7TeV is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb-1. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily.BMWF and FWF (Austria); FNRS and FWO(Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil);MES
(Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF(Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland);
CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of
Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, andUASLPFAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR(Russia);MESTD (Serbia); SEIDI and CPAN(Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA)
Measurement of cross sections for b jet production in events with a Z boson in p(p)over-bar collisions at root s=1.96 TeV
No full textA measurement of the b jet production cross section is presented for events containing a Z boson produced in p[overline p] collisions at sqrt(s)=1.96 TeV, using data corresponding to an integrated luminosity of 2 fb[superscript -1] collected by the CDF II detector at the Tevatron. Z bosons are selected in the electron and muon decay modes. Jets are considered with transverse energy ET>20 GeV and pseudorapidity |eta|<1.5 and are identified as b jets using a secondary vertex algorithm. The ratio of the integrated Z+b jet cross section to the inclusive Z production cross section is measured to be 3.32±0.53(stat)±0.42(syst)×10[superscript -3]. This ratio is also measured differentially in jet ET, jet eta, Z-boson transverse momentum, number of jets, and number of b jets. The predictions from leading-order Monte Carlo generators and next-to-leading-order QCD calculations are found to be consistent with the measurements within experimental and theoretical uncertainties
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