Measurements of new physics in top quark decay at LHC

A summary of ATLAS and CMS results on searches for new physics in top quark decay is presented. Three analysis are reported: the ATLAS and CMS searches for flavor changing neutral currents (FCNC) in top-quark decays and the CMS search for baryon number violation (BNV) in top-quark decays. ATLAS and CMS provided exclusion limits (at 95% CL) on the FCNC decay t -> Zq, using respectively 2.1 fb(-1) and 5.0 fb(-1) of pp collisions at root s = 7 TeV collected in 2011. Upper limits on B(t -> Zq) are respectively 0.73% and 0.24%. CMS has also set an exclusion limit (at 95% CL) on the BNV decay t -> lbq using 5.0 fb(-1) of data. Upper limit on B(t -> lbq) is 0.67%

ALICE detector upgrades

The LHC with its unprecedented energy offers unique opportunities for groundbreaking measurements in p+p, p+A and A+A collisions even beyond the baseline experimental designs. ALICE is setting up a program of detector upgrades, which could to a large extent be installed in the LHC shutdown planned for 2017/18, to address the new scientific challenges. We will discuss examples of the scientific frontiers and will present the corresponding upgrade projects under study for the ALICE experiment.Comment: Contribution to QM2011, 4 pages, second version with minor textual changes after review proces

Measurement of the inclusive jet cross section in pp collisions at s\sqrt{s} = 7 TeV

The inclusive jet cross section is measured in pp collisions with a center-of-mass energy of 7 TeV at the Large Hadron Collider using the CMS experiment. The data sample corresponds to an integrated luminosity of 34  pbfb$^{−1}$. The measurement is made for jet transverse momenta in the range 18–1100 GeV and for absolute values of rapidity less than 3. The measured cross section extends to the highest values of jet pT ever observed and, within the experimental and theoretical uncertainties, is generally in agreement with next-to-leading-order perturbative QCD predictions

Quarkonium Results in PbPb Collisions at CMS

We summarize the results from the study of charmonium and bottomonium via the dimuon decay channel in PbPb collisions with the CMS experiment. We discuss the observation of sequential suppression of the Upsilon states. We present preliminary results of prompt J/psi and psi' production, as well as of non-prompt J/psis coming from the weak decay of b-quarks. This latter measurement is sensitive to b-quark energy loss. We discuss the results and compare to model predictions.Comment: 8 pages, 4 figures. Proceedings of 29th Winter Workshop on Nuclear Dynamic

Measurement of the t-channel single top quark production cross section in pp collisions at √s=7TeV

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMElectroweak production of the top quark is measured for the first time in pp collisions at √s=7  TeV, using a data set collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36  pb−1. With an event selection optimized for t-channel production, two complementary analyses are performed. The first one exploits the special angular properties of the signal, together with background estimates from the data. The second approach uses a multivariate analysis technique to probe the compatibility with signal topology expected from electroweak top-quark production. The combined measurement of the cross section is 83.6 ± 29.8 (stat+syst) ± 3.3(lumi) pb, consistent with the standard model expectationWe thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (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); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLPFAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA

Search for gluino mediated bottom- and top-squark production in multijet final states in pp collisions at 8 TeV

Artículo escrito por muchos autores, sólo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración y los autores que firman como pertenecientes a la UAMA search for supersymmetry is presented based on events with large missing transverse energy, no isolated electron or muon, and at least three jets with one or more identified as a bottom-quark jet. A simultaneous examination is performed of the numbers of events in exclusive bins of the scalar sum of jet transverse momentum values, missing transverse energy, and bottom-quark jet multiplicity. The sample, corresponding to an integrated luminosity of 19.4 fb−1, consists of proton–proton collision data recorded at a center-of-mass energy of 8 TeV with the CMS detector at the LHC in 2012. The observed numbers of events are found to be consistent with the standard model expectation, which is evaluated with control samples in data. The results are interpreted in the context of two simplified supersymmetric scenarios in which gluino pair production is followed by the decay of each gluino to an undetected lightest supersymmetric particle and either a bottom or top quark–antiquark pair, characteristic of gluino mediated bottom- or top-squark production. Using the production cross section calculated to next-to-leading-order plus next-to-leading-logarithm accuracy, and in the limit of a massless lightest supersymmetric particle, we exclude gluinos with masses below 1170 GeV and 1020 GeV for the two scenarios, respectivelyWe congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MEYS (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 NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN(Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEPCenter, IPST and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A.P. Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation à la Recherche dans lʼIndustrie et dans lʼAgriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS programme of Foundation for Polish Science, cofinanced by EU, Regional Development Fund; and the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSR

Tests of CMS hadron forward calorimeter upgrade readout box prototype

A readout box prototype for the CMS Hadron Forward calorimeter upgrade was built and tested in the CERN H2 beamline. The prototype was designed to enable simultaneous tests of different readout options for the four anode upgrade PMTs, new front-end electronics design and new cabling. The response of the PMTs with different readout options was uniform and the background response was minimal. Multi-channel readout options further enhanced the background elimination. Passing all the electronic, mechanical and physics tests, the readout box proved to be capable of providing the forward hadron calorimeter operational requirements in the upgrade era.U.S. Department of Energy ; NSF ; RMKI-KFKI (Hungary), Russian Ministry of Education and Science, Russian State Committee for Atomic Energy, Scientific and Technical Research Council of Turkey (TÜBİTAK) Turkish Atomic Energy Agency (TAEK) and Bogazici University Research Fund.publisher versio

Search for new physics in events with same-sign dileptons and jets in pp collisions at s√s = 8 TeV

A search for new physics is performed based on events with jets and a pair of isolated, same-sign leptons. The results are obtained using a sample of proton-proton collision data collected by the CMS experiment at a centre-of-mass energy of 8 TeV at the LHC, corresponding to an integrated luminosity of 19.5 fb−1. In order to be sensitive to a wide variety of possible signals beyond the standard model, multiple search regions defined by the missing transverse energy, the hadronic energy, the number of jets and b-quark jets, and the transverse momenta of the leptons in the events are considered. No excess above the standard model background expectation is observed and constraints are set on a number of models for new physics, as well as on the same-sign top-quark pair and quadruple-top-quark production cross sections. Information on event selection efficiencies is also provided, so that the results can be used to confront an even broader class of new physics models.BMWF ; FWF ; FNRS ; FWO ; CNPq ; CAPES ; FAPERJ ; FAPESP ; MES ; CERN ; CAS ; MoST ; NSFC ; COLCIENCIAS ; MSES ; RPF ; MoER ; ERDF ; Academy of Finland ; MEC ; HIP ; CEA ; CNRS ; BMBF ; DFG ; HGF ; GSRT ; OTKA ; NKTH ; DAE ; DST ; IPM ; SFI ; INFN ; NRF ; WCU ; LAS ; CINVESTAV ; CONACYT ; UASLP-FAI ; MSI ; PAEC ; MSHE ; NSC ; FCT ; JINR ; MON ; RosAtom ; RAS ; RFBR ; MESTD ; SEIDI ; CPAN ; Swiss Funding Agencies ; NSC ; ThEPCenter ; IPST ; STAR ; NSTDA ; TUBITAK ; TAEK ; NASU ; STFC ; DOE ; NSF ; e Marie-Curie programme and the European Research Council and EPLANET ; the Leventis Foundation ; the A. P. Sloan Foundation ; the Alexander von Humboldt Foundation ; the Belgian Federal Science Policy Office ; the Fonds pour la Formation a la Recherche dans l’Industrie et dans l’Agriculture ; the Agentschap voor Innovatie door Wetenschap en Technologie ; the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo ; the HOMING PLUS programme of Foundation for Polish Science, co-financed by EU, Regional Development Fund ; and the Thalis and Aristeia programmes cofinanced by EU-ESF ; the Greek NSRF.publisher versio

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy

A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4: 98 fb(-1) produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.FMSR ; FNRS and FWO ; CNPq, CAPES, FAPERJ, and FAPESP ; MES ; CERN; CAS, MoST, and NSFC ; COLCIENCIAS ; MSES ; RPF ; MoER, SF0690030s09 and ERDF ; Academy of Finland, MEC, and HIP ; CEA and CNRS/IN2P3 ; BMBF, DFG, and HGF ; GSRT ; OTKA and NKTH ; DAE and DST ; IPM ; SFI ; INFN ; NRF and WCU ; LAS ; CINVESTAV, CONACYT, SEP, and UASLP-FAI ; MSI ; PAEC ; MSHE and NSC ; FCT ; JINR ; MON, RosAtom, RAS and RFBR ; MSTD ; ; MICINN and CPAN ; Swiss Funding Agencies ; NSC ; TUBITAK and TAEK ; STFC ; DOE and NSF."publisher versio

Search for supersymmetry in final states with missing transverse energy and 0, 1, 2, or >= 3 b-quark jets in 7 TeV pp collisions using the variable alpha(T)

A search for supersymmetry in final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of root s = 7 TeV. The data sample corresponds to an integrated luminosity of 4.98 fb(-1) collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, alpha(T), is used as the main discriminator between events with genuine and misreconstructed missing transverse energy. The search is performed in a signal region that is binned in the scalar sum of the transverse energy of jets and the number of jets identified as originating from a bottom quark. No excess of events over the standard model expectation is found. Exclusion limits are set in the parameter space of the constrained minimal supersymmetric extension of the standard model, and also in simplified models, with a special emphasis on compressed spectra and third-generation scenarios.The Austrian Federal Ministry of Science and Research and the Austrian Science Fund ; the Belgian Fonds de la Recherche Scientifique, and Fonds voor Wetenschappelijk Onderzoek ; the Brazilian Funding Agencies ; the Bulgarian Ministry of Education and Science; CERN ; the Chinese Academy of Sciences, Ministry of Science and Technology, and National Natural Science Foundation of China ; the Colombian Funding Agency ; the Croatian Ministry of Science, Education and Sport ; the Research Promotion Foundation, Cyprus; the Ministry of Education and Research ; and European Regional Development Fund, Estonia; the Academy of Finland, Finnish Ministry of Education and Culture, and Helsinki Institute of Physics; the Institut National de Physique Nucleaire et de Physique des Particules/CNRS, and Commissariat a l’Energie Atomique et aux Energies Alternatives/CEA, France; the Bundesministerium fur Bildung und Forschung, Deutsche Forschungsgemeinschaft, and Helmholtz-Gemeinschaft Deutscher Forschungszentren, Germany; the General Secretariat for Research and Technology, Greece; the National Scientific Research Foundation, and National Office for Research and Technology, Hungary; the Department of Atomic Energy and the Department of Science and Technology, India; the Institute for Studies in Theoretical Physics and Mathematics, Iran; the Science Foundation, Ireland; the Istituto Nazionale di Fisica Nucleare, Italy; the Korean Ministry of Education, Science and Technology and the World Class University program of NRF, Republic of Korea; the Lithuanian Academy of Sciences; the Mexican Funding Agencies ; the Ministry of Business, Innovation and Employment, New Zealand; the Pakistan Atomic Energy Commission; the Ministry of Science and Higher Education and the National Science Centre, Poland; the Fundac¸ao para a Ciencia e a Tecnologia, Portugal; JINR, Dubna; the Ministry of Education and Science of the Russian Federation, the Federal Agency of Atomic Energy of the Russian Federation, Russian Academy of Sciences, and the Russian Foundation for Basic Research; the Ministry of Education, Science and Technological Development of Serbia; the Secretaria de Estado de Investigacio´n, Desarrollo e Innovacion and Programa Consolider-Ingenio 2010, Spain; the Swiss Funding Agencies ; the National Science Council, Taipei; the Thailand Center of Excellence in Physics, the Institute for the Promotion of Teaching Science and Technology of Thailand, Special Task Force for Activating Research and the National Science and Technology Development Agency of Thailand ; the Scientific and Technical Research Council of Turkey, and Turkish Atomic Energy Authority ; the Science and Technology Facilities Council, UK; the U.S. Department of Energy, and the U.S. National Science Foundation ; European Union ; the Leventis Foundation ; the A. P. Sloan Foundation ; the Alexander von Humboldt Foundation ; the Belgian Federal Science Policy Office ; the Fonds pour la Formation a` la Recherche dans l’Industrie et dans l’Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWTBelgium); the Ministry of Education, Youth and Sports (MEYS) of Czech Republic; the Council of Science and Industrial Research, India; the Compagnia di San Paolo (Torino); the HOMING PLUS program of Foundation for Polish Science, cofinanced by EU, Regional Development Fund; and the Thalis and Aristeia programs cofinanced by EU-ESF and the Greek NSRF.publisher versio