1 / 30

ОТЧЕТ ИЯИ РАН за 2007 год

ОТЧЕТ ИЯИ РАН за 2007 год. Участвует 16 сотрудников ОСНОВНОЕ НАПРАВЛЕНИЕ ИССЛЕДОВАНИЙ – построение моделей за рамками СМ, феноменологический анализ процессов при энергии коллайдера LHC , полное моделирование отклика детектора CMS. ОСНОВНЫЕ РЕЗУЛЬТАТЫ.

jera
Download Presentation

ОТЧЕТ ИЯИ РАН за 2007 год

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ОТЧЕТ ИЯИ РАН за 2007 год Участвует 16 сотрудников ОСНОВНОЕ НАПРАВЛЕНИЕ ИССЛЕДОВАНИЙ – построение моделей за рамками СМ, феноменологический анализ процессов при энергии коллайдера LHC, полное моделирование отклика детектора CMS

  2. ОСНОВНЫЕ РЕЗУЛЬТАТЫ • Выполнен полный расчет с учетом отклика детектора CMS по следующим темам: • эксклюзивное рождение слептонов для сигнатуры l+l- + ETmiss + no jets • поиск суперсимметрии и нарушения лептонного флейворного числа на основе сигнатуры e± + ETmiss • поиск правого заряженного калибровочного бозона и тяжелого нейтрино на основе сигнатуры e+e- + 2 jets • Разработано программное обеспечение для статистической обработки данных эксперимента CMS

  3. ОСНОВНЫЕ РЕЗУЛЬТАТЫ (II) Эти результаты вошли в CMS Physics Technical Design Report Vol.II Physics Performance. Группой ИЯИ РАН по этим темам опубликовано три CMS Analysis Notes (из 60, составивших основу PhTDR). Доля группы ИЯИ РАН составила 5%. Группа ИЯИ РАН внесла основной вклад в готовящийся в ЦЕРНе отчет о результатах рабочей встречи “Flavour in the LHC Epoch”

  4. НЕКОТОРЫЕ ПУБЛИКАЦИИ • CMS Collaboration (Austin Ball et al.). CMS technical design report, volume II: Physics performance. J.Phys.G34:995-1579,2007. • Yu.M. Andreev, S.I. Bityukov, N.V. Krasnikov, A.N. Toropin. Using the e+- mu-+ + E**miss(T) signature in the search for supersymmetry and lepton flavour violation in neutralino decays. Phys.Atom.Nucl.70:1717-1724,2007. • S.N. Gninenko, M.M. Kirsanov, N.V. Krasnikov, V.A. Matveev. Detection of heavy Majorana neutrinos and right-handed bosons. Phys.Atom.Nucl.70:441-449,2007. • N.V. Krasnikov. Unparticle as a field with continuously distributed mass.Int.J.Mod.Phys. A22: 5117, 2007. • N.V. Krasnikov et al. Searching for energetic cosmic axions in a laboratory experiment: Testing the PVLAS anomaly. Eur.Phys.J. C52: 899-904, 2007. • S.N. Gninenko, N.V. Krasnikov, A. Rubbia. Search for millicharged particles in reactor neutrino experiments: A Probe of the PVLAS anomaly. Phys.Rev.D75:075014,2007.

  5. НЕКОТОРЫЕ ДОКЛАДЫ • N.V.Krasnikov, V.A.Matveev. Search for new physics at LHC. Proceedings XIII Lomonosov conference on elementary particle physics, Moscow, Russia, 23-30 August, 2007.

  6. Отчет НИИЯФ МГУ за 2007 год Участвует 11 сотрудников ОТФВЭ Основные направления исследований 1. Построение моделей за рамками СМ, расчеты и феноменологический анализ процессов при энергиях коллайдеров Tevatron, LHC, ILC Некоторые результаты - первое наблюдение одиночного рождения топ-кварка в экпарименте D0 c использованием генератора SingleTop (CompHEP) для моделирования сигнала - исследованы перспективы поика одиночного топ-кварка на LHC, поиск на его основе W'-бозона, FCNC, anom.Wtb - проведен анализ возможностей поиска KK-состояний в стабилизированной RS модели, перспективы поиска под порогом рождения KK-состояний - исследованы возможности поика бозона Хиггса в сценариях а явных CP нарушением 2. Автоматизация вычислений и генерации событий Некоторые результаты - создана новая версия программы CompHEP с новым стандартом записи событий - реализована новая версия генератора SingleTop на базе CompHEP с включением FCNC и WTb anomalous couplings

  7. Некоторые публикации V.M.Abazov,..., E.E.Boos, ..., V.E.Bunichev,...L.V.Dudko... et al. [D0Collaboration], Evidence for production of single top quarks and first direct measurement of |V(tb)|, Phys. Rev. Lett. 98 (2007) 181802 G.~L.~Bayatian et al. [CMS Collaboration], CMS technical design report, volume II: Physics performance, J. Phys. G 34 (2007) 995. E.Boos, V.Bunichev, L.Dudko and M.Perfilov, Interference between W' and W in single-top quark production processes, Phys. Lett. B 655 (2007) 245 E.Akhmetzyanova, M.Dolgopolov, M.Dubinin Supersymmetric threshold corrections to the Higgs sector in the MSSM featuring explicit CP violation, Ядерная физика, т.70, вып.9, с.1549 (2007)‏ E.E.Boos, V.E.Bunichev, M.N.Smolyakov and I.P.Volobuev, Testing extra dimensions below the production threshold of Kaluza-Klein excitations,'' Preprint: arXiv:0710.3100 [hep-ph] E.~Boos, V.~Bunichev and H.~J.~Schreiber, Prospects of a Search for a New Massless Neutral Gauge Boson at the ILC, PreprintarXiv:0709.4535 [hep-ph] J.Alwall, E.Boos, ..., L.Dudko, ..., A.Sherstnev et al. А standard format for Les Houches event files Comput. Phys. Commun. 176 (2007) 300

  8. CompHEP – инструмент теоретических исследований в физике высоких энергий CompHEP коллаборация: Э.Боос, В.Буничев, М.Дубинин, Л.Дудко, В.Еднерал, В.Ильин, А.Крюков, В.Саврин, А.Семенов, А.Шерстнев Встроенные модели: Стандартная модель МССМ Лептокварки, W’, аномальные Wtb и FCNC вершины Модели с дополнительными измерениями ……. CompHEP (НИИЯФ МГУ): Автоматические символьные и численные вычисления от задания Лагранжиана до моделирования событий Программа в свободном доступе http://comphep.sinp.msu.ru

  9. Single Top Quark First evidence for Single top production at Fermilab in 2007 Generator SingleTop (based on CompHEP) for the signal D0 Experience CMS Analysis Active participation of SINP MSU physicists in the D0 analysis.

  10. CMS Single Top Search RDMS Team (part of the international single top group) SINP MSU: E.Boos, V.Bunichev, L.Dudko, A.Markina, V.Savrin IHEP: V.Abramov, A.Ashimova, D.Konstantinov, S.Slabospitsky • PTDR v.II (Cut based analysis)‏ • Improved by Neural Network (CMS-IN-2007/045)‏ • 1fb-1: Evidence • 10fb-1: Discovery; |Vtb|, Mtop; W', FCNC, anomalous Wtb

  11. Introduction Large Hadron Collider (LHC) Start: 2008 Two proton beams with total energy E = 14 TeV Low luminosity stage withLlow = 1033 cm-2s-1 Remember:Nev = sigma Lt with total luminosityLt = 10 fb-1per year Remember: 1 fb = 10-39 cm2s-1 Two big detectors: CMS (Compact Muon Solenoid) ATLAS (A Toroidal LHC ApparatuS) In this talk we review the search for supersymmetry

  12. ATLAS and CMS Experiments Large general-purpose particle physics detectors A Large Toroidal LHC ApparatuS Compact Muon Solenoid Total weight 7000 t Overall diameter 25 m Barrel toroid length 26 m End-cap end-wall chamber span 46 m Magnetic field 2 Tesla Total weight 12 500 t Overall diameter 15.00 m Overall length 21.6 m Magnetic field 4 Tesla Detector subsystems are designed to measure: energy and momentum of g ,e, m, jets, missing ET up to a few TeV

  13. Search for Supersymmetry Y.A.Goldman and E.P.Likhtman D.V.Volkov and V.P.Akulov J.Wess and B.Zumino Why we like SUSY? • elegant theory • technical solution of the gauge hierarchy problem • dark matter  LSP is natural candidate • consistent string theories are superstring theories

  14. SUSY, Rules of the Game MSSM – minimal supersymmetric standard model based on gauge group. For each known particle  superanalog superparticle (the same mass and internal quantum numbers, difference only in spin) g (gluon, s = 1)  (gluino , s = ½) quarks (s = ½)  squarks (s = 0) leptons (s = ½)  sleptons (s = 0) gauge bosons (photon, Z- and W-bosons) (s =1)  gaugino (s = ½)

  15. SUSY, Rules of the Game H1, H2 (two Higgs doublets) (s = 0) Higgsino (s =1/2) As a result of gaugino and higgsino mixing in mass spectrum: two chargino (s = ½) four neutralino (s = ½ ) R-parity conservation postulate  to get rid of dangerous terms leading to fast proton decay. For ordinary particles R = +1

  16. SUSY, Rules of the Game For sparticles R = -1 R-parity is conserved by construction Two important consequences: 1. At supercolliders sparticles are pair produced 2. The lightest sparticle (LSP) is stable:  dark matter candidate • Note that SUSY models with R-parity violation are possible

  17. mSUGRA Model So SUSY has to be broken and in general masses of sparticles (squarks, sleptons, gluino, gaugino, higgsino) are arbitrary that makes analysis extremely difficult. For LHC most calculations were done within so called mSUGRA model  squark, slepton, higgsino masses are universal at GUT scale  m0 Gaugino masses also universal m1/2

  18. Sparticle Production From cosmology and astrophysics  LSP is weakly interacting neutral particle. As a result LSP escapes from detection (analog of neutrino)  SUSY events are characterized by nonzero transverse missing momentum. In real life SUSY has to be broken 1. gravity mediated SUSY breaking 2. gauge mediated SUSY breaking

  19. Sparticle Production At LHC sparticles can be produced via reactions: For squarks and gluino with masses O(1) TeV squark and gluino cross sections O(1) pb

  20. The Total SUSY Cross Sections

  21. p p ~ c01 ~ ~ ~ q ~ c02 l g q q l l LHC SUSY Searches Typical Signature/decay chain: • Strongly interacting sparticles (squarks, gluinos) dominate production. • Heavier than sleptons, gauginos etc. g cascade decays to LSP. • Potentially long decay chains and large mass differences • Many high pT objects observed (leptons, jets, b-jets). • If R-Parity conserved LSP (lightest neutralino in mSUGRA) stable and sparticles pair produced. • Large ETmiss signature (c.f. Wgln). • SUSY Searches • Inclusive searches to detect SUSY with first data • Exclusive studies – performed with more data to determine model parameters • e.g. masses etc from end point measurements… ~

  22. SUSY Signatures As a result of squark, gluino decays and chargino and neutralino decays, the most interesting signatures for the search for SUSY at LHC are: • multijets plus ETmiss events • 1l plus jets plus ETmiss events • 2l plus jets plus ETmiss events • 3l plus jets plus ETmiss events • 4l plus jets plus ETmiss events

  23. Recent CMS Full Simulation Results SUSY signatures: 1. EmissT + (n > 2) jets For tan(beta) =10, m0 = 60 GeV, m1/2=250 GeV, sign(mu) = +1 the 5 sigma discovery is for Lt=2 pb-1 first 4 hours of LHC work !!! 2. The same sign dimuons + EmissT + (n>2) jets For Lt =10 fb-1 SUSY masses up to 1.5 TeV

  24. CMS SUSY Discovery Potential

  25. Recent CMS Full Simulation Results 3. Single muon + EmissT + (n>2) jets For Lt = 100 fb-1 5 sigma discovery for SUSY masses up to 2TeV. 4. Opposite sign leptons + EmissT + (n>2) jets Basically similar to signature with single muon

  26. Dilepton Invariant Mass Distributionfor the Test Point LM1

  27. LHC SUSY Discovery Potential • The main conclusion is that for mSUGRA model LHC will be able to discover SUSY with squark and gluino masses up to 2 .5 TeV for Ltot = 100 fb-1 • Chargino and neutralino pairs produced through DY mechanism may be detected through their leptonic decays The signature: 3 isolated leptons without jet activity. LHC is able to detect such DY production with masses up to 200 GeV

  28. Determination of Sparticle Masses In many cases LHC is able not only to discover SUSY but to determine SUSY breaking parameters (combinations of sparticle masses). For instance, using l+ l- invariant mass distribution in reaction it is possible to determine the combination as endpoint in edge structure with the accuracy of 2-3%

  29. Conclusions • CMS & ATLAS have significant discovery potential • LHC will be able to discover SUSY with squark and gluino masses up to 2.5 TeV. There is nonzero probability to find something beyond SM or MSSM(extra dimensions, Z’-boson, compositeness ...) • Heavy gauge bosons up to ~5-6 TeV • Heavy neutrino up to 2.6 TeV • RS model ED up to ~4 TeV

  30. Conclusions At any rate after LHC we will know the mechanism of electroweak symmetry breaking (Higgs boson or something more exotic?) and the basic properties of the matter structure at TeV scale.

More Related