Project X Physics Opportunities

1Lankford – PAC Nov. 1, 2007

Project X Physics Opportunities

A.J. LankfordUC Irvine

Fermilab Physics Advisory CommitteeNov. 1, 2007


Introduction

Beyond its synergy with the ILC, the case for a major project such as Project X must be based on its physics impact.• Primarily its discovery potential

• Secondarily, its strong suite of sound physics measurements

Steering group received many physics suggestions pertinent to Project X.

Criteria for a mid-term physics program: • Will the physics be important in a global context when the experiment is done?

• Can it be done uniquely or substantially better at Fermilab than at other labs?

- Compare w/ J-PARC neutrino/flavor physics program

- Is there a community for these experiments?

• Is the experiment unique in its physics reach?

- Will the experiment answer questions not answered at the LHC?

Project X offers several opportunities that meet these criteria.


Overview of Opportunities

Project X offers many physics opportunities in:• Neutrino physics

- Long-baseline neutrino experiments

- Neutrino interaction experiments at low and high energies

• Flavor physics- Kaon physics

- Muon physics

- Charm physics

- Hyperon physics

My apologies:• Not all possibilities (or even all presented to FSG) will be discussed here.

• Giving an overview of a physics program of such breadth is humbling.- I will do my best. Apologies for my oversights and errors.

• Please see the input received by the Steering Group.


Neutrino PhysicsProject X can (simultaneously) provide neutrinos produced by:

• 8 GeV protons from 8 GeV superconducting linac >10 x currently available beam power, without impact on NuMI flux

• 50-120 GeV protons from Main Injector~3-7 x ANU upgrade for NOvA (~13 x present power)

• 800 GeV protons from TeVatron- Non-existent now; 4x1019 pot/yr with ~5% impact on NuMI flux


Neutrino Physics

Neutrino experiments have recently produced surprising discoveries:• Large neutrino oscillation/mixing

and left us with some of the most puzzling questions:• Why is the neutrino sector different from the quark sector?

as well as some of the most tantalizing possibilities:• Does CP violation in neutrino sector and leptogenesis explain the universe’s

matter-antimatter asymmetry?

Neutrino mixing is studied in long-baseline experiments.• In U.S., MINOS is running; NOvA is being developed• Plus experiments in Japan and Europe

Recent studies of neutrino oscillation program commissioned:• NuSAG (HEPAP+NSAC)• FNAL/BNL study group


Long-baseline neutrino experiments

Primary goal of long-baseline neutrino experiments• Complete understanding of neutrino mixing and oscillations:

- Determine ordering & splitting of neutrino mass states• Δmij

2 , mass hierarchy- Measure the mixing angles

• θij, especially θ13 (not yet measured)- Determine whether CP is violated in neutrino mixing

• Only θ13 accessible to reactor neutrino experiments• Naturally, none of this physics is accessible at Terascale colliders.

Study of CP violation in leptonic sector is especially compelling.• Could explain problem of matter-antimatter asymmetry via leptogenesis

Mass hierarchy is also important, e.g. to:• Determine if CP is violated in neutrino sector• Determine if neutrino mass is related to unification• Interpret outcome of neutrinoless double-beta-decay experiments

Possibility for discovery of other new physics arising from sterile neutrinos, extra dimensions, …


Long-baseline neutrino experiments

Achieving the full program of θ13, hierarchy, and CP violation will require a neutrino physics program that extends beyond the next generation of long-baseline neutrino oscillation experiments.• Inceased neutrino flux• Increased detector mass (acceptance)• Product of beam power and detector mass >10 x NOvA generation• Preferably, longer baselines, possibly lower beam energies (w/ same power)

Next generation experiments:• In Japan: T2K w/ J-PARC• In U.S.: NOvA w/ Proton plan including improvements for NOvA (700kW)

Next-to-next generation experiments:• In Japan: projected larger detector, more beam power, longer baseline (?)• In U.S.: subject of study, e.g.:

- Wide-band beam vs. off-axis beam- Water Cerenkov vs. liquid argon TPC

• In any case, future will require more intense beams.


Neutrinos with Project X

Project X can provide intense neutrino beams for long-baseline expt’s over a range of energies.• (Note: ~60 GeV is optimum for generating wide-band beam to DUSEL.)

> 2MW for 50 < Eproton < 120 GeV

- 3x NOvA p-plan @ 120 GeV

- 7x NOvA p-plan @ 50 GeV

Project X offers marked improve-ment over NOvA p-plan.Project X is also markedly better than SNuMI proposal.

- 2x SNuMI @ 120 GeV

- 5x SNuMI @ 50 GeV

Project X also provides protons at8 GeV for other programs.


NOvA θ13 Reach with Project X

θ13 reach will be much greater with a larger detector.


Neutrino Physics Reach with Project X

Sensitivity to Mass Hierarchy Sensitivity to CP Violation

Dashed curves: 95% C.L. Solid curves: 3σ

3yr. ν + 3 yr. anti-ν

Solid curves: 3σ 3yr. ν + 3 yr. anti-ν


Notes to previous slide

Sensitivity to Mass Hierarchy Sensitivity to CP Violation

• Normal hierarchy shown. Inverted hierarchy similar but reflected about δ=π.

A-C) NOvA 15kt detector

D) Two 100kt LAr detectors at 1st (700km) + 2nd (810km) oscillation maxima with Project X and NuMI beamline

E) One 100kt LAr detector (equivalent to ~300kT water Cerenkov) at 1300km using a wide-band neutrino beam with Project X

• Normal hierarchy shown. Inverted hierarchy similar but reflected about δ=π.

A) Two 100kt LAr detectors at 1st (700km) + 2nd (810km) oscillation maxima with Project X and NuMI beamline

B) One 100kt LAr detector (equivalent to ~300kT water Cerenkov) at 1300km using a wide-band neutrino beam with Project X at 60GeV


Neutrino Physics Reach with Project X

Project X significantly improves θ13 & mass hierarchy reach of NOvA.• Improvement as ~sqrt(beam power)• (Note: In conjunction w/ T2K, marked improvement in hierarchy.)

A wide-band beam from Project X directed to a large underground detector at long baseline (e.g. in DUSEL) offers impressive sensitivity to θ13 , mass hierarchy, and CP violation.• Sensitivity to mass hierarchy nearly 100x NOvA sensitivity (wrt. sin22θ13 )• Sensitivity to CP violation >10x sensitivity at shorter baseline (w/ similar mass)• In principal, given a new beamline, initiating the next-to-next generation

long-baseline experiment does not need to await Project X.

A large neutrino detector in DUSEL could also:• Probe unification, i.e. by searching for proton decay• Perform high-statistics studies of atmospheric neutrinos• Perform astrophysical searches: relic-supernova ν‘s, supernova ν bursts

Project X neutrino program offers enticing synergy w/ NSF’s DUSEL.


v Physics with 8 GeV & 800 GeV Protons

8 GeV• 8 GeV protons beyond needs of NuMI consumption exist in NOvA p-plan.

- Available 8 GeV protons similar now and in NOvA plan

- No ‘excess’ 8 GeV protons available w/ SNuMI

• 8 GeV program w/ SNuMI would require ‘tax’ on NuMI flux.

• Project X can provide protons in excess of NuMI consumption>10x current 8 GeV proton availability

- Providing a richer 8 GeV program, w/ no tax on long-baseline program

• Some possibilities presented to Steering Group:- Study of low-energy neutrino interactions for neutrino oscillation experiments

- Measurement of strange quark contribution to nucleon spin

- Study of cross-sections from very low-energy neutrinos from stopped π’s

800 GeV• A TeVatron fixed-target neutrino beamline could provide neutrinos for

precision electroweak measurements.


MicroBooNE: low-E v interactonsProposal from Fleming, Willis, et al.

More on this proposed experiment will be presented tomorrow.

Study individual final states of low-energy νe-like events

• An excess recently observed by MiniBooNE.- Incompatible with simple two-flavor oscillations?

- A new background relevant to oscillation experiments in this energy range?

• Excellent low-energy sensitivity using a liquid argon TPC

Demonstration of effectiveness of LArTPCs for backgrounds to ν interactions• Useful experience towards development of potential large long-baseline

LArTPCs


Strange Contribution to Nucleon Spin1-page “proposal” from Tayloe

Strange quark contribution to nucleon spin (Δs) is an unsolved puzzle.• Current results from deep-inelastic scattering appear inconsistent and are

model dependent

Neutral current elastic scattering preferable (a la FINeSSE) • Strange quark spin contribution appears in the nucleon axial form factor

• Measure ratio of NC-elastic/CC-elastic events

• Higher precision and less model dependence for Δs determination

• In addition, because NC-elastics dominate for νμ and ντ in core-collapse supernovae => cosmological interest

Requires ~2x1020 POT in neutrino mode + ~ 4x1020 POT in anti-neu mode

Need to track recoiling nucleon (to separate p and n)

Existing SciBooNE experiment may be able to perform measurement• Requires additional run time (2-3 yrs)

• May require detector upgrades, e.g. tracking (under investigation)


NuSOnG: Precision E-W MeasurementsEoI from Conrad, Fisher, et al.

More on this proposed experiment will be presented tomorrow.

Precision measurements of high-energy neutrino scattering• Neutrinos produced in TeVatron fixed target ν beam

- Sign-selected quadrupole train for beam purity• With Project X, a small (~5%) tax on long-baseline program

Complementary to LHC program• Once Higgs mass is measured, mhiggs becomes input to e-w theory.• Then e-w tests become powerful tool for probing physics beyond SM.• Moreover, neutrino scattering probes phenomena inaccessible to LHC/ILC.

Precision measurement of weak mixing angle θW via νμ-e scattering• Complementary probe of BSM physics wrt. other e-w measurements

- Only invisible width of Z0 in e+e- collisions similar• Presently, hints of BSM in global e-w fits exist.• Measurement of sin2 θW to 0.7% with 2x1020 protons on target

Discovery potential


NuSOnG: Precision E-W Measurements

NuSOnG: ν Scattering On Glass• 3500 tons in 4 detector modules• Sampling calorimeter, charged particle

tracking, muon spectrometers

High statistics: >20k ν-e scatters (100x NuTeV) >100k ν-q scatters

• Complementary, independent channels• Comparable statistics for anti-ν’s• ~5 yr run(Note: Detailed run plan may have changed

in talk tomorrow.)

Rich menu of precision neutrino measurements


Neutrino Physics Summary

• Project X, coupled with a large underground detector at long baseline, can provide a compelling next-to-next generation experiment probing masses, mixings, and CP violation in the neutrino sector.• This experiment is likely to be the flagship of the Project X program.

• A large neutrino detector in DUSEL could also probe nucleon stability and unification.

• Project X also provides enough protons to support neutrino experiments at low and at high neutrino energies.• A precision neutrino scattering experiment in a TeVatron fixed target

program can probe the electroweak interaction in a manner complementary to the LHC, with discovery potential and an extensive physics program.

• Neutrino experiments at low-energy can probe neutrino interactions that explore open questions, serve the oscillation program, and explore new neutrino detection techniques.


Flavor Physics – Motivation

Why is flavor physics interesting?

• Flavor physics is sensitive to new physics at ΛNP >> Eexperiment

• The New Physics flavor puzzle:

If there is NP at the TeV scale, why are FCNC so small?

• The Standard Model flavor puzzle:

Why are the flavor parameters small and hierarchical?

Why are the neutrino flavor parameters different?

• The puzzle of the baryon asymmetry:

Flavor suppression fills KM baryogenesis

Flavor matters in leptogenesis

From Yossi Nir seminar, UC Irvine, Oct 2007


Flavor Physics – Motivation

Why is flavor physics interesting?

• Flavor physics is sensitive to new physics at ΛNP >> Eexperiment

- NP in loops/penguins contributes to decays at lower energies.

- In the past, flavor at low scale has led to discoveries of (or constraints on) new physics at much higher scales.

Precision flavor experiments can probe very high energy scales.

• The New Physics flavor puzzle:

If there is NP at the TeV scale, why are FCNC so small?- New particles predicted by Terascale physics typically predict new contributions to

flavor-violating and CP-violating processes.

- At present, precision measurements show no deviations from SM.

• B factories: FCNC are small in s → d, c → u, b → d, b → s

Precision flavor experiments will probe NP discovered at the TeV scale.- E.g., differentiate among models; distinguish among SUSY-breaking mechanisms


Precision Flavor PhysicsQuark sector

Minimal Flavor Violation (MFV) is a class of models in which the only sources of flavor violation are the SM Yukawa couplings.• MFV solves the NP flavor puzzle because flavor violation effects are small.

• Gauge-mediated SUSY is an example of MFV.

Small flavor violating effects suggest maximizing experimental sensitivity to small contributions from new physics by concentrating experimental searches on rare processes that are:• theoretically clean

• experimentally clean

K→πνν (K+→π + νν and K0→π0νν) is generally considered the most promising rare decay for sensitive searches for flavor violation.• Strongly suppressed in Standard Model: B(K→πνν)~few x 10-11

• Theoretically clean

• Sensitivity at SM level experimentally tractable but challenging


K

The uncertainty of the SM prediction is mostly due to uncertainty of

the CKM parameters and not to hadronic matrix elements:

• B(B(K+→π + νν ) ) (1.6×10 (1.6×10-5-5)|Vcb|)|Vcb|44[[σηση22+(+(ρρcc--ρρ))22] ] (8.0 ± 1.1)×10 (8.0 ± 1.1)×10-11-11

- Theoretical uncertainty expected to be 3-4% in 2012.Theoretical uncertainty expected to be 3-4% in 2012.

• B(B(K0→π0νν) ) (7.6×10 (7.6×10-5-5)|Vcb|)|Vcb|44ηη22 (3.0 ± 0.6)×10 (3.0 ± 0.6)×10-11-11

- Theoretical uncertainty expected to be 1-2% in 2012.Theoretical uncertainty expected to be 1-2% in 2012.

BSM can give large (model dependent) enhancements.


NP Reach of the K decaysfrom Augusto Ceccucci at Kaon 07


K0 0

B(K0→π0νν) ~ 3x10-11; σtheory ~ 1-2%

=> lots of kaons => lots of protons => Project XBSM enhancements from 10% to 4000%

Would like at least 1000 K0 decays for σstatistical ~ σtheory • Not yet observed; limits 104 above SM• Staged KEK/J-PARC program may detect ~100 SM decays

- J-PARC I (2012) ~20 SM decays- J-PARC II (~2016) ~100 SM decays

• Project X ~800 SM decays

Past experimental proposals: KAMI (FNAL) & KOPIO (BNL)• KOPIO approved as part of RSVP project; RSVP subsequently scuttled

- (Note: cancellation not based on lack of scientific merit.)- Use TOF to constrain kinematics

• J-PARC experiment uses KAMI-like technique based on hermeticity


K0 0

Bryman, Littenberg, Zeller – Expression of Interest to Steering Group• “A KL→π0νν Experiment at Fermilab”

• Using techniques similar to KOPIO- Use 8 GeV proton beam to produce low energy kaons

- Use Accumulator ring to micro-bunch proton beam

- Determine kaon momentum via beam time-structure + Time-of-Flight

- Fully constrained reconstruction of pi-zero

• 2.5 yrs for twice sensitivity of KOPIOIntense Project X proton beam provides:

• More intense, smaller kaon beam• Improved hermeticity (KOPIO/KAMI hybrid)• Reduced background

Staged program possible:• First: Booster: reach SM discovery level• Then: Project X: near theoretical error

More sensitive than J-PARC program• also complementary technique


K+ +

B(K+→π+νν) ~ 8x10-11; σtheory ~ 3-5%

=> lots of kaons => lots of protons => Project X

BSM enhancements from 10% to 400%

Would like more than several 100’s K+ decays for σstatistical ~ σtheory

• 3 events observed by BNL E787-949 (1.8x SM)

• NA48/3 expects ~100 events by 2012

• Project X with TeVatron as stretcher ring could provide ~300-600 events/yr- with 5-10% tax on NuMI flux

Past experimental proposal: CKM (FNAL)

Fermilab capabilities (compared with other facilities):• Project X => ~20x kaon exposure

• TeVatron stretcher => reduces instantaneous rates; reduces NuMI tax

• Separated K+ beamline (e.g. with ILC crab cavities) => 5-10x beam purity


K+ +

Complementary to measurement of K0→π0νν

Rich physics program with charged kaon decays• High efficiency open-geometry detector

• Precision measurements and rare decays, e.g.:

- B(K+→eν) / B(K+→μν); sensitive to BSM

- K+ →πμe; quark-lepton LFV; factor ~100 improvement

- K+ →π -μ+μ+, K+ →π -μ+ e+; LFV; factor ~1000 improvement


Precision Flavor PhysicsLepton sector

Lepton Flavor Violation (LFV) discovered in neutrino oscillations.• Large LFV in neutral lepton sector• Source of LFV unknown• Relationship to flavor violation in quark sector unknown

Standard model predicts very small charged LFV .

Many NP models predict charged LFV at measurable rates.• e.g., unification, SUSY, heavy-neutrino mixing

•ΛNP >> Eexperiment

Muon and electron number violation searches favored experimentally.• LFV w/ taus limited by tau flux and backgrounds• μ-→e-γ

- Muon-to-Electron-Gamma expt. (MEG) at PSI, projected sensitivity 10-13

- Further improvements probably background limited

• μ-to-e conversion in field of nucleus: μ-N→e-N- Current limit from SINDRUM2 at PSI: Rμe < 6x 10-13


μ→e Conversion

μ→e conversion powerful probe for new physics at & above TeV scale.

Compositeness 103 – 104 TeV scale

Supersymmetric models predict Rμe~ 10-15 for weak scale SUSY

(Courtesy of Andre de Gouvea)

Experimental sensitivities ~ 10-17 - 10-18 achievable

Curves based on CFLV effective Lagrangian. Model parameter interpolates

between flavor transition magnetic moment type operator and a LFV 4-fermion operator.


μ→e Conversion

MECO is a model for a Fermilab μ→e conversion experiment.• Extends sensitivity by 104

• Would utilize 8 GeV Project X beam+ Accumulator & Debuncher rings

- Project X intensity might enableoptimized muon beam andimproved sensitivity.

Molzon & Prebys, Miller, et al.expressions of interest to FSG(More on this expt. tomorrow.)

Staged program possible• Start at Booster• Improve w/ Project X

Straw Tracker

Crystal Calorimeter

Muon Stopping Target

Muon Beam Stop

Superconducting Production

Solenoid (5.0 T – 2.5 T)

Superconducting Detector Solenoid (2.0 T – 1.0 T)

Superconducting Transport Solenoid (2.5 T – 2.1

T)

Collimators


Charm at TeVatron

Mixing in the D0 meson system constrains models of New Physics.• D0 mixing discovered at B-factories

CP violation here would provide compelling evidence of New Physics.

TeVatron fixed target program could provide large event samples• 35-65k per year => ~10 x (BABAR+BELLE) w/ better lifetime resolution

• Improvements over past charm fixed target experiments enabled by advances in rad-hard tracking, vertex triggering, and computing.

If no Super-B factory, TeVatron fixed target program could be unique opportunity for these measurements.(with a small tax on neutrino program)


Physics with Antiprotons

Fermilab operates world’s most intense antiproton source.• No present or planned facility exceeds its capabilities

• At present, p-bar source is dedicated to TeVatron collider program

Physics opportunities with antiproton source:• Precision charmonium studies, a la E760/E835

- Several new states of interest seen at B-factories

• Open charm studies, including mixing & CP violation

• Hyperon studies, including hyperon CP violation & rare decays

• Search for glueballs & gluonic hybrids

• Trapped p-bar and anti-hydrogen studies

An LoI from Kaplan, et al. with focus on:• Studies of states in charmonium region

• Search for new physics in hyperon decay


Precision Physics Summary

• Precision measurements of ultrarare decays probe ΛNP >> Eexperiment

• A μ→e conversion experiment searching for Charged Lepton Flavor Violation can probe for new physics at, or far above, the TeV scale, with excellent discovery potential and without impact on the neutrino program.

• A precision experiment measuring flavor violation in KL→π0νν decay has discovery potential and capability to elucidate new physics found at LHC. It also does not impact the neutrino program.

• A precision K+ + experiment can strongly complement the KL→π0νν experiment, particularly in elucidating new physics from LHC. On its own, it also has discovery potential and the capability to elucidate new physics. It can measure many rare decay modes. Its impact on the neutrino program is small.

• Capability at Fermilab to study charm and hyperons with antiprotons is unequaled elsewhere.


Reflections on a Program

• Project X offers a large, strong set of physics opportunities.• A number of opportunities with strong discovery potential exist.

• A rich set of opportunities in neutrino physics & flavor physics exist.

• There are many opportunities from which to choose.

• In general, the most interesting experiments are nth generation, and consequently, challenging and demanding precision.

• It is no wonder that we have heard of these measurements before. They are fundamental, important measurements.

• Project X does offer opportunity for a compelling physics program.

• The Project X physics program will likely be limited not by the physics opportunities, but by the resources & time to mount the complete program.

• The Project X physics program will fit well in a diverse national (and international) program that also includes exploring the energy frontier (LHC, ILC) and the cosmological frontier (dark matter, dark energy).


Outline of a Potential Program

1. Provide as much beam power as possible to the Main Injector for the long-baseline neutrino program

• First to NOvA• As soon as possible, to detector in DUSEL for neutrinos & proton decay

2. Provide excess 8 GeV protons to:• μ→e conversion• KL→π0νν• Continue a “Booster” neutrino program (e.g.MicroBooNE)

3. Impose a small tax on neutrino program in order to feed the TeVatron for:

• Precision neutrino electroweak measurements (e.g.NuSOnG)• K+ +

4. Initiate additional experiments as possible:• e.g., antiproton program, other fixed target experiments

This potential program is very ambitious, but very exciting.

Documents

Project X Physics Opportunities