Search For Large Extra Dimensions in p ¯ p collider at √ s = 1 . 96 TeV Piyali Banerjee Universite de Montreal April 16, 2009 p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Plan of the talk I Theory of Large Extra Dimensions (LED) Tevatron Accelerator D Ø Detector Data Analysis Efficiencies Background Estimation Monte Carlo Signal Generation Systematics Limit Setting Result p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Theory Of LED I Standard Model (SM) based on SU (3) C × SU (2) L × U (1) Y gauge symmetry. Describes interaction of bosons and fermions. Gravity is not included p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Theory Of LED I “TeV scale extra dimensional model → LED (Arkani-Hamed,Dimopoulos and Dvali)” large spatial compactified dimensions n to our normal 3+1 dimensional space-time universe 3+1 (3-brane) dimensions form a n+4 (bulk) dimensional universe. SM particles are pinned to this 3-brane while gravity via graviton can propagate into these additional n space dimensions p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Theory Of LED II Gauss’s Law gives; Planck scale M s , observed Planck scale M Pl , the size of the extra dimension R and number of extra dimensions n [ M Pl ] 2 ∼ R n [ M s ] n +2 (0.1) If R can be large compared to Planck length, M s can be as low as TeV The fundamental Planck scale is now at TeV, the hierarchy problem is avoided If M s ∼ 1 TeV then R goes as 10 (30 /n ) − 19 m, so R ∼ 10 11 m for n = 1 , ∼ 1 mm for n = 2 , ∼ 3 nm for n = 3 , ∼ 10 fm for n = 6 . p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Theory Of LED III probe for LED must be through the graviton interactions. φ ( k ) ( x ) e i� � � k · � y/R φ ( x, y ) = · · · (0.2) k 1 k n A graviton in the extra dimensions is equivalent from the 3 + 1 dimensional point of view to a tower of infinite number of Kaluza-Klein (KK) states with mass = 2 πk R , k = 0 , 1 , 2 , ..... ∞ . 1 The coupling strength of each of the KK states is M P l . A large number of modes can be excited at energy O( M s ) p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Signatures of LED in Collider Experiment I The collider based limits on M s come from two channels: 1 direct graviton emission 2 virtual graviton emission Gravity effects interfere with SM production amplitudes. Three terms contributing to production cross section: SM, interference, direct gravity effects: d 2 σ dMdcosθ ∗ = f SM + η G f int + η 2 G f KK (0.3) where f SM , f int and f KK are functions of (M,cos θ ∗ ). p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Signatures of LED in Collider Experiment II Effect of ED parameterized by a single variable: η G = F/M 4 (0.4) s GRW : (Giudice, Rattazzi, Wells, hep − ph/ 9811291 F = 1 (LO) HLZ : (Han, Lykken, Zhang, hep − ph/ 9811350 F = log( M 2 2 s /s ) for n = 2 , F = n − 2 for n > 2 (subleading n dependence) ⇒ different invariant mass and cosθ ∗ distribution as compared to pure SM process. p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Experimental Status I Collider Experiment Channel limits e + e − → γ ( Z ) G k L3 M d > 1 . 5 − 0 . 51 TeV for n = 2 − 8 e + e − → γ ( Z ) G k all LEP M d > 1 . 6 − 0 . 66 TeV for n = 2 − 6 p → jet + G k CDF p ¯ M d > 0 . 55 − 0 . 6 TeV for n = 4 − 8 direct graviton emission p → jet + G k D Ø p ¯ M d > 1 − 0 . 6 TeV for n = 2 − 7 p → γ ( Z ) G k D Ø p ¯ M d > 884 − 778 GeV for n = 2 − 8 p → γ ( Z ) G k CDF p ¯ M d > 549 , 581 and 601 GeV for n=4, 6, and 8 p → e + e − and γγ CDF p ¯ M s > 1 . 17 − 0 . 79 TeV for n = 3 – 7 p → e + e − and γγ virtual graviton emission D Ø p ¯ M s > 1 . 0 − 1 . 4 TeV for n = 7 – 2 p → µ + µ − D Ø p ¯ M s > 0 . 85 − 1 . 27 TeV for n = 7 – 2 p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Non Collider I p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Non Collider II Constraints on large ED δ =2 δ =3 constraint max R min M D max R min M D (mm) (mm) (TeV) (TeV) Gravitational force law 0.2 0.6 SN1987A cooling by graviton 7 x 10 –4 10 9 x 10 –7 0.8 emission 30 2.5 Diffuse cosmic ray background 9 x 10 –5 25 2 x 10 –7 1.9 ( G (k) � � γ γ �� ��������������������������� 167 22 ��������������������������� 450 30 heating of neutron stars 8 x 10 -6 90 3.5 x 10 -8 5 (trapped G (k) decaying) 1700 60 p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Tevatron Accelerator I p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Tevatron Accelerator II p SOURCE: _ DEBUNCHER & ACCUMULATOR LINAC PRE-ACC BOOSTER 8 GeV INJ TEVATRON EXTRACTION p V e for FIXED TARGET EXPERIMENTS G 2 0 1 MAIN INJECTOR (MI) P8 A0 P2 SWITCHYARD TeV EXTRACTION & RECYCLER COLLIDER ABORTS P3 A1 B0 P1 F0 p ABORT RF CDF DETECTOR p 150 GeV p INJ & LOW BETA _ 150 GeV p INJ p _ TEVATRON p (1 TeV) C0 E0 p (1 TeV) _ p ABORT DO DETECTOR _ & LOW BETA D0 Figure: The general layout of the collider facility at Fermilab. p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
The Fermilab Accelerator complex accelerates the proton and antiproton to energy of 980 GeV Collides at √ s = 1 . 96 TeV at the two collision points located at CDF and D Ø . Eight different acclerators (six circular and two linear) H − ions are made from hydrogen atoms by addition of electrons. H − ions are accelerated by Cockroft-Walton to 750 KeV. Linac, 150 m long accelerator raises energy of H − to 400 MeV Enters booster Passes through carbon foil which strips of the electrons creating protons. p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
Figure: Schematic view of the collider facility at Fermilab. Booster → 400 MeV to 8 GeV. Debuncher → large energy and narrow time spread into narrow energy and large time spread in 100 msec. p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
D Ø Detector I η = 0 η = 1 [m] Muon Scintillators 5 Muon Chambers η = 2 η = 3 Shielding 0 Calorimeter Toroid –5 –10 –5 0 5 10 Figure: A view of the D Ø Run II upgraded detector. Weighs 5500 tons, measures 13m(height) × 11m × 17m (length) The D Ø uses right handed cylindrical coordinate system such that the direction of the protons is the positive z direction positive y direction points up. p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
D Ø Detector II Transverse spread ∼ 30 microns; longitudinal spread ∼ 30 cm Luminosity monitor at z = 140 cm measures inelastic p ¯ p collisions N = σL (0.5) 2 . 37 m long beryllium beam pipe and extends radially 37 . 6 − 38 . 1 mm η = 0 η = 1 [m] Preshower Solenoid η = 2 0.5 Fiber Tracker η = 3 Silicon Tracker 0.0 –0.5 1.2 m –1.5 –1.0 –0.5 0.0 0.5 1.0 1.5 p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
D Ø Detector III Primary interaction vertex, resolution ∼ 35 µ m along z Position resolution 15 µ m in r- φ Momentum resolution ∼ 5 % for p T ≃ 10 GeV at | η | = 0 Silicon module ⇒ “ladders”, Barrels- | z | = 6 . 2 , 19 , 31 . 8 cm H-disks- | z | = 100 . 4 , 121 cm F-disks- | z | = 12 . 5 , 25 . 3 , 38 . 2 , 43 . 1 , 48 . 1 , 53 . 1 cm Secondary vertex resolution ∼ 40 µ m in r- φ and ∼ 80 µ m in r-z Scintillating fibers a.) ���������������� b.) CENTRAL CALORIMETER CRYOSTAT WALL 8 concentric cylinders MAGNIFIED� CPS + y END-VIEW FPS SOLENOID + x (20 cm - 52 cm) # 8 # # 7 stereo # 6 axial 5 Eight doublet layers CFT # 4 th i barrel # 3 stereo # 2 axial 1 2 axial and two stereo at ± 3 0 # j barrel th SMT H-disk &� Enclosure Be BEAM PIPE Be BEAM PIPE | η | < 1 . 7 where i, j = 1,...,8� LEVEL 0 + Z i = j Light from the fibers is converted to electrical pulse(Visible light photon Counters) p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
D Ø Detector IV Momentum resolution ∼ 8 % for p T ≃ 45 GeV Position resolution ≃ 100 µm p collider at √ s = 1 . 96 Piyali Banerjee Universite de Montreal Search For Large Extra Dimensions in p ¯
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