New Ideas for a Super B Factory Steve Playfer University of Edinburgh ILC Forum, Cosener’s House, May 2006

The Current B factories 10 9 B meson pairs in each experiment by Autumn 2008 (1/ab) /fb BaBar BELLE

Current CKM Status Unitarity Triangle angles and sides are all measured: V td, V cb, V ub,  by BaBar and BELLE V ts by CDF and D0

The Standard Model triumphs again in the Heavy Flavour sector So why do we want to produce yet more B mesons? …and what has it got to do with a workshop on the International Linear Collider?

We don’t understand Flavour Physics! Why are there three generations? Why are the lepton and quark couplings different? Why are the Standard Model CKM parameters what they are? What is the flavour structure of new Physics at the Electroweak scale? –Most studies assume Minimal Flavour Violation, but this has to be checked!

Physics Topics at SuperB Improve CKM constraints –angles  are statistics limited –V ub can also be improved Discrepancies in rare b  s transitions? –sin2  in b  s penguins –A FB in b  sl + l - Forbidden processes –  – D 0 mixing and CP Violation

Comparison of Sin2  spectator diagrams penguin diagrams Penguin results are consistently lower (but never by more than 2  ) “Naïve average” not reliable (different theory predictions for different decay modes) b s _d_d u,c,t _d_d

Low q 2 : A FB > 0.19 (95% C.L.) Standard Model: 0.03 BaBar A FB in B  K*l + l - Belle Low q 2 : A FB > 0 Standard Model fit shown

Recent activity CERN workshops on Flavour in the LHC era (November, February, May) Frascati workshops on Super B (November, March) Daresbury Meeting (April) Things are evolving rapidly. No baseline design. No version control. I will do my best to summarize!

LHCb and SuperB are complementary! MeasurementLHCbSuperB Phase of V ts  s  No Rare B s decays  s  Unlikely Angle  s  D s K, KK  DK Angle  Difficult  b  s penguins  s  K s b  sl + l - B  K*l + l - Inclusive V ub No? Inclusive b  ul Exclusive B  , c and decays with  only at SuperB?

Super KEK-B Higher beam currents More RF cavities Smaller  * and crab crossing Luminosity 2-5 x Integrate 20-50/ab by x B meson pairs Proposal submitted to KEK by BELLE last year.

Linear Collider B factory “An electron-positron linear collider as a B-anti B Meson factory” (Amaldi & Coignet 1986) Idea resurrected at Hawaii Super B workshop (Pantaleo Raimondi, April 2005) “Super B: a linear high luminosity B factory” (J.Albert et al, hep-physics/ ) Benefits from all the Linear Collider R&D that has been going on in the last 20 years. Looks feasible to get luminosity of 1-2 x at Y(4S)

First Linear Super B scheme with acceleration and energy recovery (to reduce power) e- Gun 2GeV e+ DR IP 5GeV e+ SC Linac e- Dump 7GeV e+ 4 GeV e- 4GeV e- SC Linac 2 GeV e+ injection 2 GeV Linac1.5 GeV Linac Linac Damping Rings 2 GeV Linac e + Gun e - Gun Use Superconducting Linacs to recover energy Use low energy damping rings to reduce synchrotron radiation –Maybe no e - damping ring Use bunch compression and final focus a la ILC Energy and asymmetry tunable Polarized beams possible

Compressor Decompressor Compressor DeCompressor IP Optional Acceleration and deceleration Optional Acceleration and deceleration FF ILC damping rings ILC final focus ILC bunch compressor Colliding every 50 turns Acceleration optional Crossing angle optional Second design of Super B Latest design has no acceleration and a crossing angle

Parameters of Super-B Designs Collider yy N y*y* sEFLumin Units10 mmmGeV(~Hd)10 35 PEP-IINormal KEKBNormal Super- PEP-II High I low  y Super- KEKB High I low  y Linear SuperB Single pass SuperB Bunch shorten SuperB X’ing angle John Seeman, FPCP 2006

Single Pass Linear Collider Scheme Collide each bunch once very hard and then recycle it –Vertical emittance blow up x300 Use very small beta functions to achieve high luminosity Re-inject disrupted bunch into damping ring for ~6 damping times –Need very short damping time (~1ms) –High power requirement for damping ring Collision frequency 120Hz x 10000bunches is ~1MHz

Single pass Super B collider N bunches =12000 in two 6km damping rings E(e+) = 7GeV E(e-) = 4 GeV  x =30  m  y =10nm  z =100  m  z =4mm in DR  e =100MeV  e /e=2*10 -2  e /e=5*10 -4 in DR  e_Luminosity =7MeV  x =0.8nm  x_norm =8  m  y =0.002nm  y_norm =20pm  z =2.0  m Stored time between collision = 1msec = 50turns Luminosity (50 turns) = 0.9*10 36 Luminosity better with single turn = 1.5*10 36

Colliding every turn with Bunch Compression Install ILC like final focus in the damping rings –Room for long enough straight section or use an arc inside the ring Choose a much lower disruption to avoid blowing up the bunch too much Use bunch compression/decompression to shorten bunches for the final focus Use monochromator scheme to compensate the energy spread at the IP to match the Y(4S) resonance

Comparison of Rings (Andy Wolski ) SuperBILC e - (e + )PEP-II e+PEP-II e- Circumference 3 km6.7 km2.2 km Beam energy 4(7) GeV5 GeV3.1 GeV9 GeV Bunch charge 2× × × ×10 10 N o bunches Current 1.6 A0.4(0.2) A2.4 A1.5 A Bunch length 4 mm6 mm11 mm Energy spread 0.11%0.13%0.07% Horiz. emit. 0.4 nm0.5 nm35 nm60 nm Vert. emit nm 1.4 nm Damping Time 10 ms27 ms70 ms37 ms

Contradictory requirements at IP Disruption Luminosity Energy spread - important at Y(4S)! Decrease number of bunches Decrease bunch length Increase spot size Increase number of bunches Decrease spot size Decrease number of bunches Increase bunch length Increase spot size

Most recent Ideas Optimum is to collide every turn Use bunch compression/decompression Use double rings –First ring for damping –Second ring for compression and final focus Use crossing angle (2x25mrad) Compensate disruption at IP using a travelling focus Some of these ideas are also relevant to ILC Some tests are planned at Frascati (DAFNE)

Large Crossing Angle Scheme Collide with 2x25mrad crossing angle Only small longitudinal part of bunch gives luminosity, but various solutions possible: –Compensate with very small vertical beta function using an ILC type final focus –Use travelling focus in horizontal plane –Crab cavities In this scheme the disruption is small and strong damping is not needed.

SYNERGY BETWEEN ILC and SuperB? “Synergy …is frequently described as the = 5 effect to denote the fact that the combined performance is greater than the sum of its parts.” Corporate Strategy, H.I.Ansoff (1965)

Synergy between PEP-II and KEK-B

If only the first of these statements is true the SuperB factory is parasitic to the ILC The second statement is what sells SuperB to the ILC community! Synergy between SuperB and ILC should also be a win/win situation The SuperB factory will be a better machine because of the ILC AND The Linear Collider will be a better machine because of SuperB

Damping Rings ILC 5 GeV SuperB 4-7 GeV Electron rings almost identical Positron rings somewhat different Same lattice Similar damping times Different sizes (3km - 6km) Different currents Different RF frequencies Similar bunch patterns Final focus inserted into rings (SuperB)

Final Focus Same bunch compression Similar IP geometry Different beam energies! CM energy resolution (SuperB) Different sources of backgrounds Different crossing angles (2-25 mrad) Different bunch trains (ILC) Different disruption parameters Different currents Final focus inserted into rings (SuperB)

Comments on Timescales ILC construction assumed to begin somewhere between 2010 and 2020 SuperB construction assumed to begin somewhere between 2010 and 2014 They may be operating in sequence and/or in parallel: –SuperB may precede the ILC –SuperB is unlikely to be after ILC Does it help more to have SuperB before ILC, or is it the same if they are in parallel?

Comments on Sites SuperB and ILC at different sites –Large difference in location of damping rings? –Differences in detailed design parameters –Both need the full currents of the damping rings for luminosity Frascati’s idea, and Italy is keen to host. –Need new tunnel There are existing 2-6 km rings –PEP, KEK, Tevatron, HERA ILC have plans for new damping ring test facilities

Searching for New Physics Method I - Go to higher energies (LHC, ILC) –Produce new particles. –Measure masses and main decay modes. Method II - Go to higher precision (LEP, B, ILC) –Produce lots of known particles. –Make accurate measurements of couplings –Measure rare decays. Method III - Look for “forbidden” things (  …) –Neutrino masses, mixing and CP violation. –Lepton flavour violation. –Electric dipole moments. To get a complete picture we should do all of these