Measurement of K + + ×Ø at Fermilab

November 13, 2009 Fermilab PAC Meeting 1

Measurement of K++×Ø at Fermilab

Jack Ritchie University of Texas at Austin

+David Jaffe

Brookhaven National Laboratory

representing the P996 Collaboration


• 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.

Overview of K+ +×Ø at Fermilab

8979194


Outline

• 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

JR

DJ


K++×Ø in the Standard Model

• A single effective operator• Dominated by top quark (charm

significant, but controlled)• Hadronic matrix element shared with

Ke× • Largest uncertainty from CKM elements

(which will improve)

• Remains clean in New Physics models

The K×Ø decays are the most precisely calculated FCNC decays.

BSM(K++×Ø) = (8.5 ± 0.7) x 1011

Brod and Gorbahn, PRD 78, 034006(2008)

μL L L μ L(s γ d )(ν γ ν )


Summary of SM Theory UncertaintiesCKM parameter uncertainties dominate the error budget today.

SM theory error for KL 0×Ø mode is no longer smaller. U. Haisch, arXiv:0707.3098

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

30% deviation from the SM

would be a 5 signal of NP


General MSSM with R-parityEffect of a ±5% measurement at a hypothetical non-SM BF

Points from a scan of MSSM parameters that satisfy experimental constraints except

B(K+ +×Ø)

SM

E949 already provides a significant constraint.

New Physics models with generic flavor structure typically induce large effects in these decays.

Buras et al, NP B714,103(2005)


68% and 95% allowed regions for NP based on measurements of

BXs and BXs l+l

SM±5% at the SM BF

±5% measurement of

B(K+ +×Ø) will provide strong constraints on New Physics within MFV, or may demonstrate failure of the MFV hypothesis.

Minimal Flavor Violation

C = C CSM,

where C characterizes the Z-penguin

MFV allowed

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)


K++×Ø in the LHC EraNew 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+ +×Ø and KL 0×Ø have 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.


All of these experiments used stopped kaons.

BNL E787 E949

with detector upgrade

K++×Ø History

David Jaffe will explain the E949 technique and how E949 experience has been extrapolated to estimate P996 performance.


K++×Ø at CERN

• 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

CERN NA-62 is a first-generation decay-in-flight experiment.


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.

o 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.


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.


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.

Tevatron in Stretcher Mode

slow extraction


K+ Yield

• 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

Relative P996/E949 K+ yields from multiple models consistent.

Ratio(P996/E949) = 6.8±1.7

Calculation of K flux into the detector is based on:

Factors w.r.t. E949 are used to estimate P996 fluxes, sensitivity, and backgrounds. [D. Jaffe]

Factor 6 more stopped K/sec

with similar total beam (+K) into the detector


Separated 550 MeV/c K+ BeamDesign by Jaap Doornbos (designer of BNL LESB-III)

Short 13.7 m

Ray tracing results

targetstoppingat 5.2K

Q3-Q8 quads and S1-S3 sextapoles likely from BNL (not assumed in cost estimate)


P996 will use an existing hall to avoid civil construction. Several possibilities identified. Example: CDF B0 Hall

150 GeV p beam1014 p/pulse (27 s)95% duty factor

K-production target

Detector


Backup Slides


Other Possible P996 Measurements


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 KL0×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.


Form factor from Ke3

Radiative correction 0.003

Bottom line - BSM(K++×Ø) = (8.5 ± 0.7) x 1010 (9% err)

Top loop 70% of BF; NLO in perturbation theory, good to 2%

Charm loop 30% of BF; recent calculations reduce error to 2.3%; remaining parametric uncertainty from charm quark mass

K++×Ø in the Standard Model

Higher dimn charm loop, long-dist

u-quark effects;

(0.04±0.02)


K++×Ø Motivation

• No matter what happens at LHC, there are key flavor-physics measurements that will be needed.

– K++×Ø is 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 KL0×Ø and 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 KL0e+e and KL0+


Sensitivity to New Physics

2)()( xiSM eXXKB

New Physics can be

parameterized by a

function ,

which is calculable in

perturbation theory for

given models.

xieXX

Significant deviations from the SM are possible.

XSM

General MSSM with R-parityBuras et al, NP B714,103(2005)

General MSSM with R-parity

Scan of parameters imposing experimental constraints except B(K+ +×Ø)


0 0.5 1.0 1.5 2.0 2.5 3.0 ( x 10 10)

B(K+ +×Ø)

Littlest Higgs model with T-parity Blanke et al., arXiv:0906.5454

E949One of many examples of NP scenarios with factor >2-3 effects possible for B(K+ +×Ø) w.r.t. SM


Effect of a ±5% measurement at BF = 2.0 x 1010


NA-62 Schedule

Source: Augusto Ceccucci, August 2009 (Extreme Beam)


NA-62 Detector Layout

P996P996


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Measurement of K + + ×Ø at Fermilab

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