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

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

НЕКОТОРЫЕ ПУБЛИКАЦИИ CMS Collaboration (Austin Ball et al.). CMS technical design report, volume II: Physics performance. J.Phys.G34: ,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: ,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: ,2007. N.V. Krasnikov. Unparticle as a field with continuously distributed mass. Int.J.Mod.Phys. A22: 5117, N.V. Krasnikov et al. Searching for energetic cosmic axions in a laboratory experiment: Testing the PVLAS anomaly. Eur.Phys.J. C52: , 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.

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

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

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) 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: [hep-ph] E.~Boos, V.~Bunichev and H.~J.~Schreiber, Prospects of a Search for a New Massless Neutral Gauge Boson at the ILC, Preprint arXiv: [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 Некоторые публикации

CompHEP (НИИЯФ МГУ): Автоматические символьные и численные вычисления Автоматические символьные и численные вычисления от задания Лагранжиана до моделирования событий от задания Лагранжиана до моделирования событий Программа в свободном доступе 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 …….

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

CMS Single Top Search PTDR v.II (Cut based analysis) Improved by Neural Network (CMS- IN-2007/045) 1fb -1 : Evidence 10fb -1 : Discovery; |V tb |, Mtop; W', FCNC, anomalous Wtb 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

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

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 t Overall diameter m Overall length 21.6 m Magnetic field 4 Tesla Detector subsystems are designed to measure: energy and momentum of,e,, jets, missing E T up to a few TeV ATLAS and CMS Experiments Large general-purpose particle physics detectors Compact Muon Solenoid A Large Toroidal LHC ApparatuS

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

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)

SUSY, Rules of the Game H 1, H 2 (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

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

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 m 0 Gaugino masses also universal m 1/2

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

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

The Total SUSY Cross Sections

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 p T objects observed (leptons, jets, b-jets). If R-Parity conserved LSP (lightest neutralino in mSUGRA) stable and sparticles pair produced. –Large E T miss signature (c.f. Wgl ). 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… l q q l g ~ q ~ l ~ ~ ~ p p ~

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 E T miss events 1l plus jets plus E T miss events 2l plus jets plus E T miss events 3l plus jets plus E T miss events 4l plus jets plus E T miss events

Recent CMS Full Simulation Results SUSY signatures: 1. E miss T + (n > 2) jets For tan(beta) =10, m 0 = 60 GeV, m 1/2 =250 GeV, sign(mu) = +1 the 5 sigma discovery is for L t =2 pb -1 first 4 hours of LHC work !!! 2. The same sign dimuons + E miss T + (n>2) jets For L t =10 fb -1 SUSY masses up to 1.5 TeV

CMS SUSY Discovery Potential

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

Dilepton Invariant Mass Distribution for the Test Point LM1

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 L tot = 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

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%

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

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.