Lankford – PAC Nov. 1, Project X Physics Opportunities A.J. Lankford UC Irvine Fermilab Physics Advisory Committee Nov. 1, 2007

Lankford – PAC Nov. 1, 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.

Lankford – PAC Nov. 1, 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.

Lankford – PAC Nov. 1, Neutrino Physics Project 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 GeV protons from Main Injector ~3-7 x ANU upgrade for NOvA (~13 x present power) 800 GeV protons from TeVatron -Non-existent now; 4x10 19 pot/yr with ~5% impact on NuMI flux

Lankford – PAC Nov. 1, 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

Lankford – PAC Nov. 1, 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 Δm ij 2, mass hierarchy -Measure the mixing angles θ ij, especially θ 13 (not yet measured) -Determine whether CP is violated in neutrino mixing Only θ 13 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, …

Lankford – PAC Nov. 1, Long-baseline neutrino experiments Achieving the full program of θ 13, 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.

Lankford – PAC Nov. 1, 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 < E proton < 120 GeV -3x NOvA 120 GeV -7x NOvA 50 GeV Project X offers marked improve- ment over NOvA p-plan. Project X is also markedly better than SNuMI proposal. -2x 120 GeV -5x 50 GeV Project X also provides protons at 8 GeV for other programs.

Lankford – PAC Nov. 1, NOvA θ 13 Reach with Project X θ 13 reach will be much greater with a larger detector.

Lankford – PAC Nov. 1, Neutrino Physics Reach with Project X Sensitivity to Mass HierarchySensitivity 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

Lankford – PAC Nov. 1, Notes to previous slide Sensitivity to Mass HierarchySensitivity 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 1 st (700km) + 2 nd (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 1 st (700km) + 2 nd (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

Lankford – PAC Nov. 1, Neutrino Physics Reach with Project X Project X significantly improves θ 13 & 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 θ 13, mass hierarchy, and CP violation. Sensitivity to mass hierarchy nearly 100x NOvA sensitivity (wrt. sin 2 2θ 13 ) 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.

Lankford – PAC Nov. 1, 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.

Lankford – PAC Nov. 1, MicroBooNE: low-E v interactons Proposal from Fleming, Willis, et al. More on this proposed experiment will be presented tomorrow. Study individual final states of low-energy ν e -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

Lankford – PAC Nov. 1, Strange Contribution to Nucleon Spin 1-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 ν μ and ν τ in core-collapse supernovae => cosmological interest Requires ~2x10 20 POT in neutrino mode + ~ 4x10 20 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)

Lankford – PAC Nov. 1, NuSOnG: Precision E-W Measurements EoI 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, m higgs 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 θ W via ν μ -e scattering Complementary probe of BSM physics wrt. other e-w measurements -Only invisible width of Z 0 in e+e- collisions similar Presently, hints of BSM in global e-w fits exist. Measurement of sin 2 θ W to 0.7% with 2x10 20 protons on target Discovery potential

Lankford – PAC Nov. 1, 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

Lankford – PAC Nov. 1, 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.

Lankford – PAC Nov. 1, Flavor Physics – Motivation Why is flavor physics interesting? Flavor physics is sensitive to new physics at Λ NP >> E experiment 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

Lankford – PAC Nov. 1, Flavor Physics – Motivation Why is flavor physics interesting? Flavor physics is sensitive to new physics at Λ NP >> E experiment -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

Lankford – PAC Nov. 1, Precision Flavor Physics Quark 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 K 0 →π 0 νν) is generally considered the most promising rare decay for sensitive searches for flavor violation. Strongly suppressed in Standard Model: B(K→πνν)~few x Theoretically clean Sensitivity at SM level experimentally tractable but challenging

Lankford – PAC Nov. 1, K   The uncertainty of the SM prediction is mostly due to uncertainty of the CKM parameters and not to hadronic matrix elements: B()  (1.6×10 -5 )|Vcb| 4 [ση 2 +(ρ c -ρ) 2 ]  (8.0 ± 1.1)×10 -11B(K + →π + νν )  (1.6×10 -5 )|Vcb| 4 [ση 2 +(ρ c -ρ) 2 ]  (8.0 ± 1.1)× Theoretical uncertainty expected to be 3-4% in B()  (7.6×10 -5 )|Vcb| 4 η 2  (3.0 ± 0.6)×10 -11B(K 0 →π 0 νν)  (7.6×10 -5 )|Vcb| 4 η 2  (3.0 ± 0.6)× Theoretical uncertainty expected to be 1-2% in BSM can give large (model dependent) enhancements.

Lankford – PAC Nov. 1, NP Reach of the K   decays from Augusto Ceccucci at Kaon 07

Lankford – PAC Nov. 1, K 0   0 B(K 0 →π 0 νν) ~ 3x ; σ theory ~ 1-2% => lots of kaons => lots of protons => Project X BSM enhancements from 10% to 4000% Would like at least 1000 K 0 decays for σ statistical ~ σ theory Not yet observed; limits 10 4 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

Lankford – PAC Nov. 1, K 0   0 Bryman, Littenberg, Zeller – Expression of Interest to Steering Group “A K L →π 0 νν 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 KOPIO Intense 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

Lankford – PAC Nov. 1, K +   + B(K + →π + νν) ~ 8x ; σ theory ~ 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 σ statistical ~ σ theory 3 events observed by BNL E (1.8x SM) NA48/3 expects ~100 events by 2012 Project X with TeVatron as stretcher ring could provide ~ 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

Lankford – PAC Nov. 1, K +   + Complementary to measurement of K 0 →π 0 νν Rich physics program with charged kaon decays High efficiency open-geometry detector Precision measurements and rare decays, e.g.: -B(K + →e ν) / B(K + →μ ν); sensitive to BSM -K + →πμe; quark-lepton LFV; factor ~100 improvement -K + →π - μ + μ +, K + →π - μ + e + ; LFV; factor ~1000 improvement

Lankford – PAC Nov. 1, Precision Flavor Physics Lepton 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 Λ NP >> E experiment 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 Further improvements probably background limited μ-to-e conversion in field of nucleus: μ - N→e - N -Current limit from SINDRUM2 at PSI: R μe < 6x

Lankford – PAC Nov. 1, μ→e Conversion μ→e conversion powerful probe for new physics at & above TeV scale. Compositeness 10 3 – 10 4 TeV scale Supersymmetric models predict R μe ~ for weak scale SUSY (Courtesy of Andre de Gouvea) Experimental sensitivities ~ achievable Curves based on CFLV effective Lagrangian. Model parameter interpolates between flavor transition magnetic moment type operator and a LFV 4-fermion operator.

Lankford – PAC Nov. 1, μ→e Conversion MECO is a model for a Fermilab μ→e conversion experiment. Extends sensitivity by 10 4 Would utilize 8 GeV Project X beam + Accumulator & Debuncher rings -Project X intensity might enable optimized muon beam and improved 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

Lankford – PAC Nov. 1, Charm at TeVatron Mixing in the D 0 meson system constrains models of New Physics. D 0 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)

Lankford – PAC Nov. 1, 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

Lankford – PAC Nov. 1, Precision Physics Summary Precision measurements of ultrarare decays probe Λ NP >> E experiment 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 K L →π 0 νν 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 K L →π 0 νν 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.

Lankford – PAC Nov. 1, 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 n th 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).

Lankford – PAC Nov. 1, 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 K L →π 0 νν 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.