BOLOGNA LHCb impact on CKM fits Vincenzo Vagnoni

BOLOGNA LHCb impact on CKM fits Vincenzo Vagnoni (for the LHCb Collaboration) Nagoya, Thursday 14 th December 2006

LHCb startup and baseline luminosity programme u Startup of LHC beam in 2007 n n n u Pilot run at 450 Ge. V per beam with full detector installed Establish running procedures Time and space alignment of the detectors, calibrations 2008: LHC ramps up to 7 Te. V per beam n Complete commissioning of detector and trigger at 14 Te. V l n u Start of first physics data taking Baseline LHCb luminosity programme n Integrated luminosity of ~0. 5 fb-1 delivered in 2008, ~2 fb-1 in subsequent years l n u Including calibration of momentum, energy and particle ID physics results with 2 fb-1 available in 2010, 10 fb-1 available in 2014 Ongoing discussion for an upgrade beyond 2014: Super-LHCb Note: instantaneous luminosity at the LHCb IP of 2· 1032 cm-2 s-1 is almost two orders of magnitude below the LHC challenges* n Thus we expect the LHCb luminosity requirements can be fulfilled very early in the LHC operation * the B-physics reach of Atlas and CMS will not be considered in this talk 2

Lattice QCD prospects u To exploit precision measurements where hadronic parameters play a role, a substantial improvement should be achieved during the following decade Now Uncertainties in LQCD calculation dominated by systematic errors, overall accuracy does not improve according to simple scaling laws Disclaimer: estimates on a 10 years scale very difficult. . . to be taken cum grano salis Vub-excl. * Vcb-excl. * Pre-LHCb 2010 2014 6 TFlop year 40 TFlop year 1 PFlop year 11% 13% 5% 5% 4% 4% 2% 2% 5% 11% 3% 6% 2. 5% 5% 1. 5% 3% 4% 2% 1. 5% 1% 6 TFlop year and 10 TFlop year predictions from S. Sharpe @ Lattice QCD: Present and Future, Orsay, 2004 and report of the U. S. Lattice QCD Executive Committee Projections to far future from V. Lubicz @ Super. B IV Workshop * no improvements on Vub- and Vcb-inclusive determinations assumed 3

Where will we be at the end of the B-factories and the Tevatron? (I) (i. e. before LHCb data) u Bd/B+ sector: B-factories n n Assume an integrated luminosity of 2 ab-1 at the (4 S) provided by Ba. Bar and Belle together, and. . . ( ) 6. 5° l n From B , B SU(2) analyses, and B ( )o time dependent Dalitz ( ) 6. 5° l From B DK, GLW, ADS and Dalitz analyses u. Assuming significant reduction of the systematics, in particular improvements in the knowledge of the D decay model, e. g. using CLEO-c data and/or model independent fits on the Dalitz plane n u (sin 2 ) 0. 017 Bs sector: Tevatron n n Assume (2 x) 6 fb-1 collected by CDF and D 0, and. . . ( s) 0. 2 First direct measurement of s from D 0 ( s/ s) 0. 04 available: s= -0. 79 ± 0. 56 ± 0. 01 ( ms) 0. 5% (see talk by B. Casey) 4

Where will we be at the end of the B-factories and the Tevatron? (II) (i. e. before LHCb data) Summer 2006 2008* u Nice improvement in 2008, in particular for n mostly due to better and LQCD * Every projection to the future shown in this talk has been obtained by fine-tuning the central values of future measurements around Standard Model expectations, i. e. no New Physics assumed ! 5

LHCb impact with first year (I) -1 physics data (int. L=0. 5 fb ) u u Data taking in 2008 will be crucial to understand detector and trigger performance and assess the LHCb potential Can use well established measurements from the B-factories and the Tevatron to “calibrate” our CP sensitivity n B-factory sin 2 (final sensitivity ~0. 017) vs LHCb-2008 J/ KS sin 2 (~0. 04) l n Will demonstrate with already considerable precision that we can keep under control the main ingredients of CP-analyses, e. g. opposite side tagging Tevatron ms (final sensitivity ~0. 09 ps-1) vs LHCb-2008 (~0. 014 ps-1, stat. only) l Hadronic trigger, control of proper time resolution, same side K tagging, etc. 6

LHCb impact with first year (II) -1 physics data (int. L=0. 5 fb ) u Perform the first high precision measurement of s n Tevatron s (final sensitivity ~0. 2) vs LHCb-2008 (~0. 04) l u Bring down the limit of BR(Bs mm) n n u Other big milestone in the search for New Physics (see talk by J. Dickens) Potential to exclude BR between 10 -8 and SM value with the first year only ! Other relevant measurements n u Could make a 5 discovery of New Physics effects in the Bs mixing phase with the first year of data if NP s is O(10°) e. g. b-hadron lifetimes, B h+h-’ (see J. Nardulli), . . . First results with “more difficult” measurements. . . get a taste of! n e. g. Dalitz analyses of B DK and B ( )o 7

sin 2 from Bd J/ KS u The golden mode at B-factories, already well known, but still relevant to improve the measurement In one LHCb year (L=2 fb-1) (sin 2 ) Yield: ~216 k Bd J/ (mm)KS events with B/S 0. 8 Sensitivity: (sin 2 ) = 0. 02 background subtracted CP asymmetry with L=2 fb-1 now pre-LHCb with LHCb at L=2 fb-1 with LHCb at L=10 fb-1 year Overall improvement by roughly a factor 2 with LHCb at L=10 fb-1 8

s and s at LHCb u Bs J/ is the el-dorado mode at LHCb n counterpart of Bd J/ KS for measuring the Bs mixing phase, but also other modes contribute l Signal yield: 130 k events per L=2 fb-1 with a B/S 0. 1 very sensitive probe of New Physics effects in the Bs mixing l s = s(SM) + s(NP) l s(SM)=-2 l 2 , small and very well known from indirect UT fits: -0. 037± 0. 002 Sensitivity with L=2 fb-1 Channels under study s 0. 021 Bs J/ , Bs c , Bs J/ , Bs Ds. Ds Γs/Γs 0. 0092 Bs J/ ( s) n now pre-LHCb at L=2 fb-1 LHCb at L=10 fb-1 year now n slight complication: 2 CP-even and 1 CPodd amplitudes, angular analysis is needed to separate the states s poorly known now, but will be known as well as sin 2 thanks to LHCb pre-LHCb at L=2 fb-1 LHCb at L=10 fb-1 year See J. van Hunen’s talk 9

Sensitivity to u u more challenging for LHCb, due to the need of reconstructing o’s in hadronic environment + - 2 analyses under study § Time-dependent Bd ( )o Dalitz plot N 3π = 14 k events / 2 fb-1, B/S~1 0 0 - + § with L=2 fb-1 LHCb estimates a sensitivity σ 10° § B SU(2) analysis l Very preliminary studies indicate the need of a few years of LHCb running to improve the u Need more time and refined studies to give firm results for n In the following we will conservatively assume to measure alpha with the Bd ( )o mode only ( ) [o] current Bd + - measurement. l With 2 fb-1 the main LHCb contribution will be most likely the improved measurement of Bd o o (fully charged final state) now LHCb Bd ( )o only pre-LHCb with LHCb at L=10 fb-1 with LHCb at L=2 fb-1 year 10

Sensitivity to n n u m- Several modes to measure at LHCb simulation ADS+GLW Dalitz analysis with D 3 -body “Dalitz” analysis with D 4 -body Golden Bs Ds. K mode r(770) Sensitivity estimated at ~4. 2° with L=2 fb-1 n Assuming the same improvements of the Dalitz syst. error as for the projections of the B-factories to 2008 B mode B+→DK+ B+→D*K+ D mode K + KK/ + K 3 K B+→DK+ Ks KK B+→DK+ B 0→DK*0 K K + KK + B 0→DK*0 Bs→Ds. K Ks KK K* and DCS K* m+ ( ) [o] u now pre-LHCb with LHCb at L=2 fb-1 at L=10 fb-1 year By 2014 sensitivity at about 2 degrees See M. Patel’s talk 11

Unitarity Triangle prospects from LHCb only 2010 LHCb L=2 fb-1 2014 LHCb L=10 fb-1 Using , , and ms from LHCb only n n + theory for md/ ms Not employing the full LHCb potential for in this study l Somewhat conservative: just from ( )o 12

Unitarity Triangle in 2014 Without LHCb With LHCb at L=10 fb-1 13

Allowing for New Physics in the mixing The mixing processes being characterized by a single amplitude, they can be parametrized in a general way by Summer 2006 means of two parameters ( , ) with NP allowed n HSMeff includes only SM box diagrams while Hfulleff includes New Physics contributions as well Four “independent” observables n n CBd, CBs, Bs CBq=1, Bq=0 in SM Using Tree-level processes For the neutral kaon mixing case, it is convenient to introduce only one parameter assumed to be NP-free 0 0 *the effect in the D -D 5 additional parameters mixing is neglected 14

The - plane in 2014 allowing for NP in the mixing Without LHCb u By allowing for arbitrary NP contributions in the mixing, the UT apex will be basically determined by the Tree-level constraints, and it will be the reference for any NP model building n u With LHCb at L=10 fb-1 caveat: neglecting here NP effects in neutral D-meson mixing LHCb will further constrain the apex, due to substantial improvement in the measurement 15

Measuring New Physics in the Bs mixing End of Tevatron u Dramatic impact of LHCb on the Bs mixing phase n n can bring down the sensitivity to the NP contribution Bs from 5. 6° at the end of the Tevatron to 0. 3° NP in the Bs mixing will be known three times better than in the Bd by 2014 l without the need of improvements from theory With LHCb at L=10 fb-1 in 2014 As far as CBd and CBs are concerned, they are dominated by theory no great impact from LHCb measurements (CBs)~0. 06 (CBd)~0. 09 16

Interpretation of s vs sin 2 u u Most precise measurements today available are md/ ms, sin 2 and |Vub/Vcb| A disagreement between md/ ms and would spot out NP in the magnitude of the mixing amplitudes n u But uncertainty on still too large To find evidence of NP effects in the Bd mixing phase, it is instead important to compare sin 2 with |Vub/Vcb| n but need to heavily rely on Lattice QCD, interpretation in case of slight disagreement not trivial Example: current UT fits show slight disagreement between sin 2 and |Vub/Vcb|, due to excess of Vub-inclusive / defect of sin 2 (JHEP 0610 (2006) 081) First NP hint or theory problem in Vub? No such interpretation problems for s, just go and measure it ! If different from -0. 037± 0. 002, NP is there 17

Conclusions u LHCb will improve the knowledge of the Unitarity Triangle n n u in particular due to increased precision on the measurement of and , and maybe to a lesser extent of both in Standard Model and (even more) in NP allowed scenarios LHCb will measure the Bs mixing phase with ultimate precision n Impressive improvement of a factor 20 since the end of Tevatron data taking l NP angle Bs will be known at 5. 6° from the Tevatron, and 0. 3° at LHCb (with int. L=10 fb -1) ! l Much easier intepretation than sin 2 , NP might show up very early just with the first year of data in 2008 l After “LHCb phase I”, in 2014, NP in the Bs mixing will be more constrained than in the B d u Other big milestones from LHCb, not impacting on CKM fits or not considered in this talk n Radiative and rare decays l Bd K* , Bs , Bd K*mm, Bs mm n b sss penguins l e. g. Bs n n B hh’ Charm physics, . . . 18

Backup 19

The LHC beauty experiment Single-arm forward spectrometer, acceptance: 15 -300 mrad Tracking: Vertex Locator, TT, T 1, T 2, T 3 PID: 2 RICH detectors, SPD/PS, ECAL, HCAL, Muon stations Forward-backward correlation of bb angular distribution B b b pp at 14 Te. V “b-factory” Luminosity at IP 8 = 2· 1032 cm-2 s-1 1012 bb produced per year including all b-hadrons species PT of B-hadron b Interaction point ~1 cm b 100μb 230μb Pythia η of B-hadron 20

LHCb Calorimeter • 4 devices: Scintillator Pad Detector (SPD), Preshower (PRS), Electromagnetic Calorimeter (ECAL) and Hadronic Calorimeter (HCAL). • Provides with acceptance 30 mrad to 300 (250) mrad: • Level-0 trigger information (high transverse momentum hadrons, electrons, photons and p 0, and multiplicity) • Kinematic measurements for and 0 with E/E = • Particle ID information for e, , and 0. 10% E 1% 21

0 reconstruction at LHCb • Resolved p 0: reconstructed from 2 isolated photons • m = 10 Me. V/c 2 • Merged p 0: pair of photons from high energy pion which forms a Resolved π0 single ECAL cluster, where the 2 showers are merged. The pair is reconstructed with a specific algorithm based on the expected shower shape. • m = 15 Me. V/c 2 • Reconstruction efficiency: e 0 = 53 % for B 0 + - 0 Merged π0 e Resolved Merged Transverse energy (Ge. V) π0 mass (Mev/c²) 22

Tree level determination of from B± D(*)0 K(*)± u W B - Interference if same D 0 and D 0 final states Favoured GLW (Gronau, London, Wyler) s l b - K c Vcb D Uses CP eigenstates of D 0 decays 0 u u ADS (Atwood, Dunietz, Soni) Colour suppressed Vub = |Vub | e-i u b B - u W c s u D K 0 Dalitz Method – GGSZ analyze D 0 three-body decays on the Dalitz plane - strong amplitude (the same for Vub and Vcb mediated transitions strong phase difference between Vub and Vcb mediated transitions r. B is a crucial parameter - the sensitivity on depends on it Break-through of B-factories, but statistically limited and extremely challenging! 23

Bounds on NP size and phase Bd dark: 68% light: 95% Bs dark: 68% light: 95% The allowed NP amplitude is still large for small phase shift MFV scenarios are strongly favored at this point, but we still might see a large NP phase in Bs mixing 24

MFV or not MFV? New Physics in the b d and recently in b s sector starts to be quite constrained and most probably will not come as an alternative to the CKM picture, but rather as a «correction» Minimal Flavour Violation: the only source of flavour violation is in the SM Yukawa couplings (implies =0) New Physics couplings between third and second families (b s sector) stronger with respect to the b d ones Flavour physics needs to improve existing measurements in the Bd sector and perform precise measurement in the Bs sector (mixing phase still largely unknown) 25

LHCb sensitivity: summary sin 2 from ( )° only s s/ s 2010 L=2 fb-1 4. 2° 2014 L=10 fb-1 2. 4° 0. 02 10° 0. 009 7° 0. 021 0. 009 0. 004 26

Perspectives up to 2014 sin 2 s s/ s Pre-LHCb 6. 5° 2010 3. 5° 2014 2. 3° 0. 017 6. 5° 0. 013 5. 4° 0. 008 4. 8° 0. 2 0. 04 0. 021 0. 009 0. 004 Pre-LHCb: B-factories and Tevatron at end of their life, 2008 -2009 27