Measurement of K +  + ×Ø at Fermilab

1. Measurement of K++×Øat Fermilab Jack Ritchie University of Texas at Austin + David Jaffe Brookhaven National Laboratory representing the P996 Collaboration Fermilab PAC Meeting

2. Overview of K++×Ø at Fermilab • Measure B(K++×Ø) to ±5% using the method developed in BNL E787/949. • Build a modern detector based on the E949 concept. • Estimate the sensitivity and backgrounds of the new experiment by extrapolating from E949 experience. • Expect events/year at SM branching fraction • Use the Tevatron as a Stretcher, filled by the Main Injector, to get high duty factor (95%). • 10% hit on protons to NOvA; no effect on microBooNE, mu2e, g-2, … • Avoid civil construction by using an existing hall. • Several possibilities have been identified. • Use an existing superconducting solenoid. • CDF or CLEO is suitable. • Estimated TPC is $53M (FY2010 $), $58M (then-year $). • Proposed schedule has first physics running by end of 2014. Fermilab PAC Meeting

3. Physics Motivation Status of Other Experiments Opportunity with the Fermilab complex Kaon Beam E949 Detector and Improvements for P966 Sensitivity and Backgrounds Cost and Schedule Summary Outline JR DJ Fermilab PAC Meeting

4. K++×Øin the Standard Model The K×Ø decays are the most precisely calculated FCNC decays. • A single effective operator • Dominated by top quark (charm significant, but controlled) • Hadronic matrix element shared with Ke× • Largest uncertainty from CKM elements (which will improve) • Remains clean in New Physics models BSM(K++×Ø) = (8.5 ± 0.7) x 1011 Brod and Gorbahn, PRD 78, 034006(2008) Fermilab PAC Meeting

5. With foreseeable improvements, it is reasonable to expect the total SM theory error ≤6%. Unmatched by any other FCNC process (K or B). A. Kronfeld analysis Summary of SM Theory Uncertainties CKM parameter uncertainties dominate the error budget today. 30% deviation from the SM would be a 5 signal of NP SM theory error for KL 0×Ø mode is no longer smaller. U. Haisch, arXiv:0707.3098 Fermilab PAC Meeting

6. General MSSM with R-parity Effect of a ±5% measurement at a hypothetical non-SM BF E949 already provides a significant constraint. Buras et al, NP B714,103(2005) New Physics models with generic flavor structure typically induce large effects in these decays. Points from a scan of MSSM parameters that satisfy experimental constraints except B(K+ +×Ø) SM Fermilab PAC Meeting

7. 68% and 95% allowed regions for NP based on measurements of BXs and BXsl+l ±5% at the SM BF SM Minimal Flavor Violation The MFV hypothesis is that all flavor- and CP-violating effects in New Physics are governed by the SM Yukawa couplings (CKM mixing and phase). Bobeth et al, Nucl Phys B726, 252(2005) ±5% measurement of B(K+ +×Ø) will provide strong constraints on New Physics within MFV, or may demonstrate failure of the MFV hypothesis. MFV allowed C = C  CSM, where C characterizes the Z-penguin Fermilab PAC Meeting

8. K++×Ø in the LHC Era New Physics found at LHC  New particles with unknown flavor- and CP-violating couplings New Physics NOT found at LHC Precision flavor-physics expts will be needed to help sort out the flavor- and CP-violating couplings of the NP. Precision flavor-physics expts will be needed since they are sensitive to NP at mass scales beyond the LHC (through virtual effects). K+ +×Øand KL 0×Øhave special status because of their small SM uncertainty and large NP reach. Precision measurement of B(K+ +×Ø) is an immediate high priority. • It is experimentally more accessible than KL 0×Ø. • The result can guide the Project-X Intensity Frontier program. Fermilab PAC Meeting

9. K++×ØHistory BNL E787  E949 with detector upgrade David Jaffe will explain the E949 technique and how E949 experience has been extrapolated to estimate P996 performance. All of these experiments used stopped kaons. Fermilab PAC Meeting

10. K++×Øat CERN CERN NA-62 is a first-generation decay-in-flight experiment. • Builds on the experience of NA-31/NA-48 collaboration • Many features in common with the Fermilab CKM proposal • but uses an un-separated charged beam (75 GeV) • Expects to collect 50 events/yr at SM level • Under construction; low-intensity run 2011, high-intensity mid-2012 Fermilab PAC Meeting

11. Stopped K’s versus Decays in Flight • A decay-in-flight experiment (CKM) was proposed at Fermilab in 1998 (by some of us). • Whatever the hypothetical advantages, the decay-in-flight method has not yet been proven for K++×Ø. • The deciding factors - here and now - are opportunity and cost: • The E949 method has been demonstrated at a level sufficient to accomplish the goals of P996. This is the opportunity. • The cost of a low-energy (550 MeV/c) electromagnetostatic separated K+ beam is significantly less than a high-energy SCRF-separated beam. • Unseparated beam results in enormous rates in some detector elements; this is the Achilles heel of NA62. • The cost of the compact (low-energy) detector is much less. Fermilab PAC Meeting

12. Why here, why now? • Existing Fermilab facilities (MI and Tevatron) provide an opportunity to make a decisive measurement. • Either New Physics will manifest, or severe constraints result. • To be timely, this should compete head-to-head with CERN’s NA-62 experiment. • Tevatron stretcher operation is only viable if done soon after collider running ends. • This measurement can provide important input for planning the Project-X Intensity Frontier program. • This experiment will be a nucleation site for rebuilding the U.S. kaon-physics community, which is needed for Project-X. Fermilab PAC Meeting

13. Tevatron in Stretcher Mode Stretcher operating scenario • With NOvA, n pulses to NuMI beam (1.33 s ramp to 120 GeV) + 2 pulses to Tevatron (1.67 s ramp to 150 GeV); n  18 10% hit in protons to NOvA; no effect on BooNE, mu2e, g-2, … • 96 Tp (1 TP = 1012 p) with 27.3 s cycle; duty factor = 94% (high duty factor is key to P996) • Extraction hardware exists; 150 GeV is the normal Tevatron injection energy; 150 GeV extraction has been done before. • If NOvA is off, higher intensity to P996 is possible. slow extraction Fermilab PAC Meeting

14. K+ Yield Calculation of K flux into the detector is based on: • LAQGSM-MARS model for ratio (150 GeV vs 21.5 GeV) accounting for target lengths, solid angles, momentum bites • A complete secondary beam design • Ray-tracing simulations from production target to stopping target • FLUKA simulations of stopping target to estimate stopping fraction. ~60% of K+ stop in active target E949 P996 Factor 6 more stopped K/sec with similar total beam (+K) into the detector Relative P996/E949 K+ yields from multiple models consistent. Ratio(P996/E949) = 6.8±1.7 Factors w.r.t. E949 are used to estimate P996 fluxes, sensitivity, and backgrounds. [D. Jaffe] Fermilab PAC Meeting

15. Separated 550 MeV/c K+ Beam Design by Jaap Doornbos (designer of BNL LESB-III)  Short 13.7 m Ray tracing results Q3-Q8 quads and S1-S3 sextapoles likely from BNL (not assumed in cost estimate) Fermilab PAC Meeting

16. P996 will use an existing hall to avoid civil construction. Several possibilities identified. Example: CDF B0 Hall Detector 150 GeV p beam 1014 p/pulse (27 s) 95% duty factor K-production target Fermilab PAC Meeting

17. Backup Slides Fermilab PAC Meeting

18. Other Possible P996 Measurements Fermilab PAC Meeting

19. Other Possible Stretcher Experiments • Next generation Drell-Yan experiment (follow up of current E906) • Next generation neutral kaon beam experiment tuned to the interference region to pursue CP and CPT studies in a variety of final states.  • Next generation hyperon experiments, such as a follow-up of the putative evidence for new physics in the +p+ signal,  such as + EDM search using bent crystals (Wah, Chicago). • A KL0×Ø experiment if the accelerator pulse timing resolution can be improved (requires R&D). • High duty factor test-beam program, which will reduce the cost to NOvA.  As configured now the test-beam program will be a 5% hit on NOvA operations, and P996 would be an additional 10%, raising the aggregate hit to 15%.  Driving test beams in parallel with P996 will reduce the aggregate NOvA hit to 10% as well as providing better test beams.  Fermilab PAC Meeting

20. K++×Øin the Standard Model Radiative correction  0.003 Form factor from Ke3 Higher dimn charm loop, long-dist u-quark effects; (0.04±0.02) Charm loop 30% of BF; recent calculations reduce error to 2.3%; remaining parametric uncertainty from charm quark mass Top loop 70% of BF; NLO in perturbation theory, good to 2% Bottom line - BSM(K++×Ø) = (8.5 ± 0.7) x 1010 (9% err) Fermilab PAC Meeting

21. K++×ØMotivation • No matter what happens at LHC, there are key flavor-physics measurements that will be needed. • K++×Øis crucial. • K++×Ø is a “golden mode” due to small SM theory errors. • Large deviations from the SM level appear in many plausible NP scenarios. • 30% deviation from the SM would be a 5 signal of NP in P996 • Precision measurement of K++×Ø, which is more accessible experimentally than KL0×Øand can be carried out now, will provide guidance for Project -X. • A NP signal will imply high priority for KL 0×Ø and the complimentary modes KL0e+e and KL0+  Fermilab PAC Meeting

22. New Physics can be parameterized by a function , which is calculable in perturbation theory for given models. Significant deviations from the SM are possible. Sensitivity to New Physics General MSSM with R-parity Buras et al, NP B714,103(2005) General MSSM with R-parity Scan of parameters imposing experimental constraints except B(K+ +×Ø) XSM Fermilab PAC Meeting

23. Littlest Higgs model with T-parity Blanke et al., arXiv:0906.5454 E949 One of many examples of NP scenarios with factor >2-3 effects possible for B(K+ +×Ø) w.r.t. SM 0 0.5 1.0 1.5 2.0 2.5 3.0 ( x 1010) B(K+ +×Ø) Fermilab PAC Meeting

24. Effect of a ±5% measurement at BF = 2.0 x 1010 Fermilab PAC Meeting

25. NA-62 Schedule Source: Augusto Ceccucci, August 2009 (Extreme Beam) Fermilab PAC Meeting

26. P996 NA-62 Detector Layout Fermilab PAC Meeting

27. Fermilab PAC Meeting