Physics with antiprotons CP violation in Dmesons Klaus

Physics with antiprotons: CP violation in D-mesons Klaus Peters Ruhr-Universität Bochum KVI Groningen Jan 7, 2003

Overview CP-Violation l Introduction l The K, B and D-case D-Mesons l Production l Decays Experimental Techniques Applications at PAn. Da l Experiments and Techniques l Requirements and Limitations 2 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Motivation CP-Violation was first observed 1963 l Christenson, Cronin, Fitch & Turlay The origin is not well established yet l SM, QCD, non-SM, … CP-Violation – important for l Baryogenesis l Baryon asymmetry Is well measured in the K-System and observed in the B-System le’/e, sin 2 b, sin 2 a No evidence in D-Systems yet l SM prediction: small, discovery ® new physics 3 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Quark-Mixing Not all neutral mesons are C-Eigenstates (like the p 0) but K 1 and K 2 are CP-Eigenstates 4 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Types of CP Violation 2 I I 5 F + F I _ I =/ 2 _ F =/ 2 _ I _ F direct CP Violation 2 _ I I _ I Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da F _ F + _ I 2 I F 7. 1. 2003

The Kaon Case Observation: l K 0 S ct=2. 68 cm decay dominant 2 p, CP=+1 l K 0 L ct=15. 51 m decay dominant 3 p, CP=-1 l Dm=(3. 49± 0. 04)x 10 -12 Me. V/c 2 but sometimes l |e|=(2. 282± 0. 017)x 10 -3 ~ G(KL® 2 p)/G(KS® 2 p) a K 0 L decays to 2 p dominated by mixing l in addition there is also direct CP violation without mixing l Re(e’/e)=(1. 8± 0. 4)x 10 -3 6 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Analysis Overview f®KSKL Concept 1 –Tagged Mode l Identify KS • neither definite CP nor Flavor l Measure decay time differences l Tagging – Systematics! Concept 2 - Untagged Mode l Measure decay time difference untagged l No systematics due to tagging l smaller statistics since both final states must be similar (like f(®KSKL)®p+p-p 0 p 0) 7 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

The Dafne Detector e+e-®f(1020) l KS : Large decay volume: low density TPC l Main CP channel f®KSKL®p+p-p 0 p 0 l g–detection for neutral p 0 reconstruction 8 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

The CKM Matrix Wolfenstein Parameterization O(l 4) Unitarity relation e. g. A=(r, h) l Vub. Vud*+Vcb. Vcd*+Vtb. Vtd*=0 l can be expressed as a triangle in complex space CP-Violation parameters la, b and g, measured quantity sin 2 f 9 e’/e a g C=(0, 0) Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da b B=(1, 0) 7. 1. 2003

The B-Meson Case: closing the triangle l The lifetime difference in the B-System is much smaller than in the K-System l instead of nearly perfect CP-Eigenstates KS/KL strong Eigenstates l CP violation appears in the time dependent decay rate 10 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Analysis Overview Y(4 s)®BBbar Basic concept Measure the B 0 time dependent decay rate of channels with definite CP l Need to know the flavor of the B 0 – Flavor Tagging! l Although 2 B’s are present – only need to reconstruct B 0 CP fully if one can “measure” the flavor of the Btag. l Gauge the Flavor-Tagging with fully reconstructed events To be included l Dilution due to Miss-Tag l Resolution smearing 11 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Analysis Overview Y(4 s)®BBbar reconstruct exclusive B decays to CP and flavour Eigenstates and tag the flavour of “the other B” select Btag events with leptons and kaons from hadronic B decays and determine B flavour select BCP candidate (like B 0®J/y. K 0 S, etc. ) and Bflavor candidates (like B 0®D*-p+) measure Miss-Tag wi and determine dilution Di=1 -2 wi effective Qi=(1 -2 wi)2 measure Dz between BCP and Btag and determine the signed time difference Dt between decays 12 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

The Ba. Bar Detector 1. 5 T solenoid Cs. I(Tl) EMC DIRC (PID) e+ (3. 1 Ge. V) Drift Chamber e- (9 Ge. V) Instrumented Flux Return Silicon Vertex Tracker Tracking : s(p. T)/p. T = 0. 13% PT + 0. 45% DIRC : K-p separation >3. 4 s for p<3. 5 Ge. V/c EMC: E/E = 2. 3% E-1/4 1. 9% 13 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

BABAR: Silicon Vertex Tracker 5 layers double sided 150. 000 channels surface ~1 m 2 point resolution s=15(40) mm for inner (outer) layers single vertex resolution s ~70 mm stand-alone tracking for low pt particles (<120 Me. V/c) 14 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Mesons – Basic Properties Charm (c) + Light Quark (u, d, s) H-Atom of QCD decay: destroying charm quantum number l no strong decays l only weak (or non-SM) decays l long lifetimes ct ~ 100 -300 mm many channels into light mesons l individual channels are usually rare 15 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D(S)-Decays W-emission (external) W-emission (internal) c c W W u, d, s W-annihilation W-exchange c c W W d, s u, d, s 16 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D(S)-Decays Cabbibo-Suppression Colour-Suppression: l CKM-Matrix: l allowed transitions Vii~1 (cosqc) l suppressed transitions Vij<1 (sinqc) l W-Boson creates a Quark. Antiquark-Pair with matching colour-anticolour (~1/32=1/9) q u c = ~cosqc ~sinqc ~-sinqc~cosqc d W s _ q 17 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D(S)-Decays D 0 c _ u c + D _ d DS 18 c +_ s W W W u _ d p+ s _ u K- u _ d s _ d u _ d s _ s c W D 0 _ K 0 c W D+ c DS W + _ s Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da s _ d u _ d p+ f u _ u p+ s _ d u _ s _ K 0 p 0 _ K 0 p+ _ K 0 K+ 7. 1. 2003

The D-Meson Case: discovery opportunities for direct effects The DDbar mixing diagrams are suppressed l small mass of d-, s- and b-quarks ~f(ms)-f(md) BBbar and KKbar enhanced l due to t-quark mass ~mt 2 Using x. D=Dm/G and y. D=DG/2 G l Osc. parameter r. D=1/2 (x. D 2+y. D 2) l r. D=G(D 0®l-X)/G(D 0®l+X) ® only bounds l SM prediction r. D=10 -8 with possible strong phase d between RS and WS l x‘=x cosd+y sind l y‘=y cosd-x sind 19 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Mesons: Mixing and Indirect CP Violation „Wrong sign“ (WS) D 0 decays l either produced via DCS or mixing and CFD l mixing parameter y can be extracted from lifetime ratio y=t. Kp/t. KK-1 l Kp has no certain CP parity l K+K- is a CP even mode Indirect CP violation occurs in the mixing l if l expected asymmetry is very small (~10 -5) l only new physics can lead to asymmetries as large as 1% 20 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Mesons: Experimental results and predictions new physics y SM x SM 21 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Mesons: Direct CP violation Recently observed in K meson decays (NA 48/k. Te. V) l requires two coherent amplitudes with l different weak phases and strong phases l only SCS decays can be used where tree and one-loop penguin interfere l expected asymmetry ACP ~ l-2 ~ 10 -3 l possible decay modes D 0®K+K-, p+p-, KSp 0, p 0 p 0, KSKS or D+®KSp+ 22 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D(S)-Production Photo-Production D g Central Production h g g, P D D g g p D g g, P E 687, E 791, E 831 (Focus) 23 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da p E 769 7. 1. 2003

Photo-Production E 687 24 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D(S)-Production Fragmentation@Y(4 s) e+ e- B-Decays D np/K W h D B l, nl D D B Babar, Belle, Cleo-C h W B 25 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da D 7. 1. 2003

D(S)-Production Threshold production e+ D e- D Mark-III, Cleo-C p _ p D D D Panda 26 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Physik @ CLEO-C (CESR-C) in 2003 CESR-c and CLEO-c become operational l sqrt(s)=3 -5 Ge. V/c 2 l L=(1. 5 -4. 4) x 1032 cm-2 s-1 l 3 yr. running envisaged Ecm L Int L Ge. V 1032 cm-2 s-1 fb-1 3. 1 1. 46 0. 5 (4 m) 1. 3 x 109 J/y 3. 69 ~4. 1 1. 5 (4 m) 109 y‘ 3. 77 ~4. 13 3 (9 m) 3 x 107 DD 4. 14 ~4. 4 3 (9 m) 1. 5 x 105 Ds. Ds 4. 6 ~4. 4 1 (3 m) 4 x 105 LCLC 27 Events Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Proposed Panda Detector (Overview) High Rates l Total s ~ 55 mb Vertexing l (sp, KS, L, …) Charged particle ID l (e±, m±, p, …) Magnetic tracking Elm. Calorimetry l (g, p 0, h) Forward capabilities l (leading particles) Sophisticated Trigger(s) 28 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Panda-Vertexing: Micro Vertex Detector 7. 2 mio. barrel pixels 50 x 300 μm pellet/cluster pipe beam pipe 2 mio. forward pixels 100 x 150 μm Readout: ASICs (ATLAS/CMS) 0. 37% X 0 or pixel one side – readout other side (TESLA) 29 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Panda-PID: DIRC (Cherenkov) Ba. Bar@SLAC less space than aero gel costs of calorimeter no problems with field 30 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Charm and Double-Charm Production Charm production is not investigated in low energy ppbar reactions so far l First goal: measure charm (D-meson, C-Hyperon) production • reconstruct exclusive channels • measure inclusive cross sections • measure decay topologies l be prepared for surprises! • like double ccbar production in e+el in e+e-®J/y. X at Y(4 s), 60% of X contains ccbar! Use this input for the design of a CP-violation experiment at PAn. Da in a later stage 31 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Pair Production and D*-Tagging D-mesons can be produced directly in ppbar reactions l Use D* mesons as a source for D 0 l B(D*+®D 0 p+)=68% l D*+®D 0 p+ is a CP-conserving strong decay l the charge of the slow! pion is an unbiased flavor tag for the D 0 l s(DDbar) ~ 100 -200 nb l rec. events ~106/year _ Alternative technique pp®p. LC+D 0 l with perfect flavor tag l but yield unknown and no dominant LC decay channel 32 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

D-Trigger Properties for a possible trigger l lifetimes 100 -300 mm l slow (recoil) pions from D* l moderate multiplicities l associated production l Lifetimes and momenta require a high trigger level (reco!) l multiplicities and KS multiplicity jumps are available “in hardware” Associated production l Need to trigger on one D • D+®KSX = (30± 4)% • D+®K±X = (30± 3)% • D 0®KSX = (21± 3)% • D 0®K±X = (56± 4)% l An efficient trigger on charged K’s and K 0 S will maintain more than 50% of the DDbar events Hadronic background: l reduced by f~10 -2 • ppbar®KSX • ppbar®K±X 33 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da ~<10 -2 stot 7. 1. 2003

Other CP-Measurements in ppbar Non-leptonic decays (|DS|=1) proceed by parity-violating weak interaction angular momentum L=0, 1 ® P=(-1)L ® interference l between S- and P-wave or |DI|=1/2 and 3/2 l observed quantities are angular distribution asymmetry a l and baryon decay polarization b (from X decays) 34 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

The Hyperon Case: CP conservation implies measure SM prediction A~10 -4 -10 -5 s~ 65 mb (LL), 2 mb (X+X-) NL ~ 109/month NX~ 3 x 107/month 35 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

The GSI Future Project Panda Existing GSI Facilities 36 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

Summary and Outlook The origin of CP violation is still unclear Using any available tool is mandatory to understand a basic feature of our subnuclear structure The D-system is a great opportunity to study direct CP-violation The new facility at GSI provides a possibility to test CP violation in l D-mesons and l Hyperon decays 37 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003

GSI & PAn. Da: More Information http: //www. gsi. de/GSI-Future/project/eng/i/pdf_e. gif http: //www. gsi. de/GSI-Future/cdr/ http: //www. gsi. de/GSI-Future/project/eng/index. php 38 Klaus Peters, RUBochum, CP- Physics with D-Mesons at PAn. Da 7. 1. 2003