Precision low energy searches for new physics

Transcription

1 Precision low energy searches for new physics Dinko Počanić University of Virginia 30 January 2009 D. Počanić (UVa) Research Talk 30 Jan 09 1 / 28

2 Outline Outline Standard Model of elementary particles and interactions Historical Motivation Pion and Muon Brief Overview of the SM The PIBETA/PEN Program Overall Physics Agenda PEN Goals and Motivation About the PEN Experiment Neutron Decay Measurements: Nab and abba Motivation and Goals of Nab/abBA Nab Measurement Principles and Apparatus Overview of SNS and FnPB D. Počanić (UVa) Research Talk 30 Jan 09 2 / 28

3 Historical Motivation Overall Motivation Since earliest times (Democritus, Greek atomists, Aristotle) humans have wondered: a. What is our world really made of? Mostly e, p and n. But, there s lots more (γ, ν... ) b. How is it held together? That s even tougher to answer! c. How did it come to be this way? The answers fit together to form a large mosaic called the Standard Model (SM). We re still fitting pieces, esp. on the edges. D. Počanić (UVa) Research Talk 30 Jan 09 3 / 28

4 Historical Motivation Overall Motivation Since earliest times (Democritus, Greek atomists, Aristotle) humans have wondered: a. What is our world really made of? Mostly e, p and n. But, there s lots more (γ, ν... ) b. How is it held together? That s even tougher to answer! c. How did it come to be this way? The answers fit together to form a large mosaic called the Standard Model (SM). We re still fitting pieces, esp. on the edges. D. Počanić (UVa) Research Talk 30 Jan 09 3 / 28

5 Historical Motivation Overall Motivation Since earliest times (Democritus, Greek atomists, Aristotle) humans have wondered: a. What is our world really made of? Mostly e, p and n. But, there s lots more (γ, ν... ) b. How is it held together? That s even tougher to answer! c. How did it come to be this way? The answers fit together to form a large mosaic called the Standard Model (SM). We re still fitting pieces, esp. on the edges. D. Počanić (UVa) Research Talk 30 Jan 09 3 / 28

6 Historical Motivation Overall Motivation Since earliest times (Democritus, Greek atomists, Aristotle) humans have wondered: a. What is our world really made of? Mostly e, p and n. But, there s lots more (γ, ν... ) b. How is it held together? That s even tougher to answer! c. How did it come to be this way? The answers fit together to form a large mosaic called the Standard Model (SM). We re still fitting pieces, esp. on the edges. D. Počanić (UVa) Research Talk 30 Jan 09 3 / 28

7 Historical Motivation Overall Motivation Since earliest times (Democritus, Greek atomists, Aristotle) humans have wondered: a. What is our world really made of? Mostly e, p and n. But, there s lots more (γ, ν... ) b. How is it held together? That s even tougher to answer! c. How did it come to be this way? The answers fit together to form a large mosaic called the Standard Model (SM). We re still fitting pieces, esp. on the edges. D. Počanić (UVa) Research Talk 30 Jan 09 3 / 28

8 Historical Motivation Overall Motivation Since earliest times (Democritus, Greek atomists, Aristotle) humans have wondered: a. What is our world really made of? Mostly e, p and n. But, there s lots more (γ, ν... ) b. How is it held together? That s even tougher to answer! c. How did it come to be this way? The answers fit together to form a large mosaic called the Standard Model (SM). We re still fitting pieces, esp. on the edges. D. Počanić (UVa) Research Talk 30 Jan 09 3 / 28

9 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

10 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

11 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

12 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

13 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

14 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

15 Early elementary particles Historical Motivation 1897 J.J. Thomson measures e/m for cathode rays and postulates the electron E. Rutherford (Geiger & Marsden) discover the atomic nucleus E. Rutherford produces protons: α + N p + X 1932 J. Chadwick discovers the neutron in beryllium rays : α + Be n + X 1932 Carl Anderson discovers the e + predicted by Dirac in D. Počanić (UVa) Research Talk 30 Jan 09 4 / 28

16 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

17 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

18 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

19 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

20 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

21 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

22 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

23 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

24 Pion and Muon The PION (and the MUON) 1935 Pion predicted by Yukawa to explain the short range NN force: heavy exchanged particle. V (r) = g r e (mc/ )r = g r e r/r 0. r 0 2 fm m 200 MeV/c 2, hence, the name meson Anderson & Neddermeyer discover π in cloud chamber tracks of cosmic rays... turns out to be the µ ( mesotron ) Tanikawa; 1943 Sakata + Inoue; 1947 Marshak + Bethe independently suggest another Yukawa meson Lattes, Muirhead, Occhialini & Powell observe π µ e in nuclear emulsions. D. Počanić (UVa) Research Talk 30 Jan 09 5 / 28

25 Cecil Powell s emulsion tracks D. Počanić (UVa) Research Talk 30 Jan 09 6 / 28

26 Physical properties of the PION Properties of the PION J π = 0 (pseudoscalar) I = 1 (3 charge states: π +, π 0, π ) m π ± 140 MeV/c 2 m π MeV/c 2 τ π ± 26 ns τ π s Not elementary has quark substructure: π + : u d π 0 : (uū d d)/ 2 π : dū For comparison: p: uud n: udd D. Počanić (UVa) Research Talk 30 Jan 09 7 / 28

27 Physical properties of the PION Properties of the PION J π = 0 (pseudoscalar) I = 1 (3 charge states: π +, π 0, π ) m π ± 140 MeV/c 2 m π MeV/c 2 τ π ± 26 ns τ π s Not elementary has quark substructure: π + : u d π 0 : (uū d d)/ 2 π : dū For comparison: p: uud n: udd D. Počanić (UVa) Research Talk 30 Jan 09 7 / 28

28 Physical properties of the PION Properties of the PION J π = 0 (pseudoscalar) I = 1 (3 charge states: π +, π 0, π ) m π ± 140 MeV/c 2 m π MeV/c 2 τ π ± 26 ns τ π s Not elementary has quark substructure: π + : u d π 0 : (uū d d)/ 2 π : dū For comparison: p: uud n: udd D. Počanić (UVa) Research Talk 30 Jan 09 7 / 28

29 Physical properties of the PION Properties of the PION J π = 0 (pseudoscalar) I = 1 (3 charge states: π +, π 0, π ) m π ± 140 MeV/c 2 m π MeV/c 2 τ π ± 26 ns τ π s Not elementary has quark substructure: π + : u d π 0 : (uū d d)/ 2 π : dū For comparison: p: uud n: udd D. Počanić (UVa) Research Talk 30 Jan 09 7 / 28

30 Physical properties of the PION Properties of the PION J π = 0 (pseudoscalar) I = 1 (3 charge states: π +, π 0, π ) m π ± 140 MeV/c 2 m π MeV/c 2 τ π ± 26 ns τ π s Not elementary has quark substructure: π + : u d π 0 : (uū d d)/ 2 π : dū For comparison: p: uud n: udd D. Počanić (UVa) Research Talk 30 Jan 09 7 / 28

31 Physical properties of the PION Properties of the PION J π = 0 (pseudoscalar) I = 1 (3 charge states: π +, π 0, π ) m π ± 140 MeV/c 2 m π MeV/c 2 τ π ± 26 ns τ π s Not elementary has quark substructure: π + : u d π 0 : (uū d d)/ 2 π : dū For comparison: p: uud n: udd D. Počanić (UVa) Research Talk 30 Jan 09 7 / 28

32 Pion and Muon Decays SM and its limitations Properties of the PION Decay Branching Fr. Nickname π + µ + ν 1.0 (π µ2 ) µ + νγ e + ν (π e2 ) e + νγ π 0 e + ν (π β ) π 0 γγ e + e γ (Dalitz) e + e e + e e + e µ + e + νν 1.0 e + ννγ e + ννe + e D. Počanić (UVa) Research Talk 30 Jan 09 8 / 28

33 Brief Overview of the SM Fundamental Interactions: the STANDARD MODEL Quarks (m 0) : J = 1 2 Gluons: J = 1, m = 0; Mesons: q q Strongly Interacting Particles ( u d ) ( c s ) ( ) t b Baryons: qqq e 1 3 e Particles Not Interacting Strongly Leptons: J = 1 2 ( ) ( ) ( e µ τ ν e ν µ ν τ ) e 0 Gauge Bosons: J = 1 W ± Z 0 γ m (GeV) D. Počanić (UVa) Research Talk 30 Jan 09 9 / 28

34 Brief Overview of the SM Fundamental Interactions: the STANDARD MODEL Quarks (m 0) : J = 1 2 Gluons: J = 1, m = 0; Mesons: q q Strongly Interacting Particles ( u d ) ( c s ) ( ) t b Baryons: qqq e 1 3 e Particles Not Interacting Strongly Leptons: J = 1 2 ( ) ( ) ( e µ τ ν e ν µ ν τ ) e 0 Gauge Bosons: J = 1 W ± Z 0 γ m (GeV) D. Počanić (UVa) Research Talk 30 Jan 09 9 / 28

35 Brief Overview of the SM Fundamental Interactions: the STANDARD MODEL Quarks (m 0) : J = 1 2 Gluons: J = 1, m = 0; Mesons: q q Strongly Interacting Particles ( u d ) ( c s ) ( ) t b Baryons: qqq e 1 3 e Particles Not Interacting Strongly Leptons: J = 1 2 ( ) ( ) ( e µ τ ν e ν µ ν τ ) e 0 Gauge Bosons: J = 1 W ± Z 0 γ m (GeV) D. Počanić (UVa) Research Talk 30 Jan 09 9 / 28

36 Brief Overview of the SM Some Shortcomings of the Standard Model arbitrary fermion (quark, lepton) masses, arbitrary number of generations, (is there a fourth?) origin of the masses? (Higgs) quark mixing (CKM parameters, CP symmetry breaking... ), quark confinement, hadron properties at low energies, transition to asymptotic freedom, exotic particles (leptoquarks, supersymmetric partners, ν R,... ) new level of substructure?... D. Počanić (UVa) Research Talk 30 Jan / 28

37 The PIBETA/PEN Program Overall Physics Agenda The PIBETA/PEN program of measurements Perform precision checks of Standard Model and QCD predictions: π + π 0 e + ν e main goal SM checks related to CKM unitarity π + e + ν e γ(or e + e ) F A /F V, π polarizability (χpt prediction) tensor coupling besides V A (?) µ + e + ν e ν µ γ(or e + e ) departures from V A in L weak 2nd phase: The PEN experiment π + e + ν e e-µ universality pseudoscalar coupling besides V A ν sector anomalies, Majoron searches, m h+, PS l-q s, V l-q s,... D. Počanić (UVa) Research Talk 30 Jan / 28

38 The PIBETA/PEN Program Overall Physics Agenda The PIBETA/PEN program of measurements Perform precision checks of Standard Model and QCD predictions: π + π 0 e + ν e main goal SM checks related to CKM unitarity π + e + ν e γ(or e + e ) F A /F V, π polarizability (χpt prediction) tensor coupling besides V A (?) µ + e + ν e ν µ γ(or e + e ) departures from V A in L weak 2nd phase: The PEN experiment π + e + ν e e-µ universality pseudoscalar coupling besides V A ν sector anomalies, Majoron searches, m h+, PS l-q s, V l-q s,... D. Počanić (UVa) Research Talk 30 Jan / 28

39 The PIBETA/PEN Program Overall Physics Agenda The PIBETA/PEN program of measurements Perform precision checks of Standard Model and QCD predictions: π + π 0 e + ν e main goal SM checks related to CKM unitarity π + e + ν e γ(or e + e ) F A /F V, π polarizability (χpt prediction) tensor coupling besides V A (?) µ + e + ν e ν µ γ(or e + e ) departures from V A in L weak 2nd phase: The PEN experiment π + e + ν e e-µ universality pseudoscalar coupling besides V A ν sector anomalies, Majoron searches, m h+, PS l-q s, V l-q s,... D. Počanić (UVa) Research Talk 30 Jan / 28

40 The PIBETA/PEN Program PEN Goals and Motivation π eν decay: SM predictions; measurements Modern theoretical calculations: B calc = Γ(π e ν(γ)) Γ(π µ ν(γ)) calc = (5) 10 4 Marciano and Sirlin, [PRL 71 (1993) 3629] (2) 10 4 Decker and Finkemeier, [Phys. Lett. B 387 (1996) 391] (1) 10 4 Cirigliano and Rosell, [PRL 99, (2007)] Experiment, world average [current PDG]: Γ(π e ν(γ)) Γ(π µ ν(γ)) exp = (1.230 ± 0.004) 10 4 PEN goal: δb B D. Počanić (UVa) Research Talk 30 Jan / 28

41 The PIBETA/PEN Program PEN Goals and Motivation π eν decay: SM predictions; measurements Modern theoretical calculations: B calc = Γ(π e ν(γ)) Γ(π µ ν(γ)) calc = (5) 10 4 Marciano and Sirlin, [PRL 71 (1993) 3629] (2) 10 4 Decker and Finkemeier, [Phys. Lett. B 387 (1996) 391] (1) 10 4 Cirigliano and Rosell, [PRL 99, (2007)] Experiment, world average [current PDG]: Γ(π e ν(γ)) Γ(π µ ν(γ)) exp = (1.230 ± 0.004) 10 4 PEN goal: δb B D. Počanić (UVa) Research Talk 30 Jan / 28

42 The PIBETA/PEN Program PEN Goals and Motivation π eν decay: SM predictions; measurements Modern theoretical calculations: B calc = Γ(π e ν(γ)) Γ(π µ ν(γ)) calc = (5) 10 4 Marciano and Sirlin, [PRL 71 (1993) 3629] (2) 10 4 Decker and Finkemeier, [Phys. Lett. B 387 (1996) 391] (1) 10 4 Cirigliano and Rosell, [PRL 99, (2007)] Experiment, world average [current PDG]: Γ(π e ν(γ)) Γ(π µ ν(γ)) exp = (1.230 ± 0.004) 10 4 PEN goal: δb B D. Počanić (UVa) Research Talk 30 Jan / 28

43 The PIBETA/PEN Program PEN Goals and Motivation π e2 Decay and the SM B(π eν) = Γ(π e2 )/Γ(π µ2 ) given in SM to 10 4 accuracy; dominated by helicity suppression (V A). Deviations can be caused by: (a) charged Higgs in theories with richer Higgs sector than SM, (b) PS leptoquarks in theories with dynamical symmetry breaking, (c) V leptoquarks in Pati-Salam type GUT s, (d) loop diagrams involving certain SUSY partner particles, (e) non-zero neutrino masses (and mixing). Proc s. (a) (d) PS currents. Most general 4-fermion π e2 amplitude: G F 2 [ ( dγµ γ 5 u ) ( ν e γ µ γ 5 (1 γ 5 )e ) f e AL In the SM: f l AL + f e PL ( dγ 5 u ) ( ν e γ 5 (1 γ 5 )e ) ] + r.h. ν term = 1, while f l xr = f Px l = 0, with l = e, µ. D. Počanić (UVa) Research Talk 30 Jan / 28

44 The f e PL The PIBETA/PEN Program and Mass Bounds PEN Goals and Motivation Allowing for LH pseudoscalar coupling [Shanker, NP B204 (82) 375]: ( B πe2 = B SM 1 + 2m ) ( πa P fpl e / 1 + 2m ) πa P f µ m e a A m µ a PL, A where 2nd term in denominator is negligible because f e PL f µ PL, while a P a A m π m u + m d 14. Therefore ( ) Bπe2 obs Bπe2 SM /Bπe2 SM = B B SM 2m πa P fpl e m e a 7700f PL e! A PEN goal is B/B , giving a 1σ sensitivity of δf e PL We can use this sensitivity to get estimates of the mass reach of PEN. D. Počanić (UVa) Research Talk 30 Jan / 28

45 The PIBETA/PEN Program PEN Mass Bounds Cont d. PEN Goals and Motivation (a) Charged Higgs, m H+ Given a mixing angle suppression S 10 2, we get f e PL S m tm τ m 2 H+ yielding m H+ > 6.9 TeV. (b) Pseudoscalar leptoquarks, m P Given an estimated effective Yukawa coupling of y 1/250, we can find m P, mass of the color-triplet PS l-q: f e PL 2 G F y 2 2m 2 P yielding m P > 3.8 TeV. (c) Vector leptoquarks, M G Followig Shanker who assumes gauge coupling g g SU(2), we have: f e PL 4M2 W M 2 G yielding M G > 630 TeV. D. Počanić (UVa) Research Talk 30 Jan / 28

46 The PEN Apparatus stopped π + beam active target counter 240-det. CsI(p) calo. central tracking digitized PMT signals stable temp./humidity The PIBETA/PEN Program BC PEN Detector 2008 π + beam About the PEN Experiment vac. pure CsI AD AT PMT PH MWPC1 MWPC2 wad (x4) 10 cm D. Počanić (UVa) Research Talk 30 Jan / 28

47 The PEN Apparatus stopped π + beam active target counter 240-det. CsI(p) calo. central tracking digitized PMT signals stable temp./humidity The PIBETA/PEN Program BC PEN Detector 2008 π + beam About the PEN Experiment vac. pure CsI AD AT PMT PH MWPC1 MWPC2 wad (x4) 10 cm D. Počanić (UVa) Research Talk 30 Jan / 28

48 The PIBETA/PEN Program About the PEN Experiment PIBETA Detector Assembly (1998) D. Počanić (UVa) Research Talk 30 Jan / 28

49 The PIBETA/PEN Program About the PEN Experiment PIBETA Detector on Platform (1998) D. Počanić (UVa) Research Talk 30 Jan / 28

50 The PIBETA/PEN Program About the PEN Experiment Experiment R (PEN) collaboration members: L. P. Alonzi, a V. A. Baranov, c W. Bertl, b M. Bychkov, a Yu.M. Bystritsky, c E. Frlež, a N.V. Khomutov, c A.S. Korenchenko, c S.M. Korenchenko, c M. Korolija, f T. Kozlowski, d N.P. Kravchuk, c N.A. Kuchinsky, c D. Mekterović, f D. Mzhavia, c,e A. Palladino, a D. Počanić, a P. Robmann, g O.A. Rondon-Aramayo, a A.M. Rozhdestvensky, c T. Sakhelashvili, g V.V. Sidorkin, c U. Straumann, g I. Supek, f Z. Tsamalaidze, e A. van der Schaaf, g E.P. Velicheva, c and V.V. Volnykh c a Dept of Physics, Univ of Virginia, Charlottesville, VA , USA b Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland c Joint Institute for Nuclear Research, RU Dubna, Russia d Institute for Nuclear Studies, PL Swierk, Poland e IHEP, Tbilisi, State University, GUS Tbilisi, Georgia f Rudjer Bošković Institute, HR Zagreb, Croatia g Physik Institut der Universität Zürich, CH-8057 Zürich, Switzerland Home page D. Počanić (UVa) Research Talk 30 Jan / 28

51 Neutron Decay Measurements: Nab and abba Motivation and Goals of Nab/abBA Neutron Decay Parameters (SM): n pe ν e kev dw de e dω e dω ν k e E e (E 0 E e ) 2 with: [ 1 + a k e k ν E e E ν + b m E e + σ n ( A k e E e + B k ν E ν + D k e k ν E e E ν a = 1 λ 2 A = 2 λ 2 + Re(λ) λ λ 2 B = 2 λ 2 Re(λ) λ 2 D = 2 Im(λ) λ 2 ) ] λ = G A G V (D 0 T invariance violation.) D. Počanić (UVa) Research Talk 30 Jan / 28

52 Neutron Decay Measurements: Nab and abba Motivation and Goals of Nab/abBA Goals of the Nab and abba Experiments δa a δb δa A δb B D. Počanić (UVa) Research Talk 30 Jan / 28

53 Neutron Decay Measurements: Nab and abba Motivation and Goals of Nab/abBA n-decay Correlation Parameters Beyond V ud Beta decay parameters constrain L-R symmetric model extensions to the SM. [Review: Herczeg, Prog. Part. Nucl. Phys. 46, 413 (2001)] Measurement of the electron-energy dependence of a and A can separately confirm CVC and absence of SCC. [Gardner, Zhang, PRL 86, 5666 (2001), Gardner, hep-ph/ ] Fierz interference term, never measured for the neutron, offers a sensitive test of non-(v A) terms in the weak Lagrangian (S, T ). A general connections exists between non-sm (e.g., S, T ) terms in d ue ν and limits on ν masses. [Ito + Prézaeu, PRL 94 (2005)] D. Počanić (UVa) Research Talk 30 Jan / 28

54 Neutron Decay Measurements: Nab and abba Nab Principles and Apparatus Nab Measurement principles: Proton phase space p p 2 (MeV 2 /c 2 ) proton phase space cos θ eν = cos θ eν = cos θ eν = E e (MeV) Note: For a given E e, cos θ eν is a function of p 2 p only. D. Počanić (UVa) Research Talk 30 Jan / 28

55 Neutron Decay Measurements: Nab and abba Nab Principles and Apparatus Measurement principles: Proton TOF response functions Yield (arb. units) E e = MeV MeV MeV Slope = a MeV p 2 p (MeV 2 /c 2 ) D. Počanić (UVa) Research Talk 30 Jan / 28

56 Neutron Decay Measurements: Nab and abba Nab Principles and Apparatus Measurement principles: Spectrometer sketch Neutron Segmented Beam Si detector 0 V 30 kv 0 V acceleration region TOF region transition region Decay Volume D. Počanić (UVa) Research Talk 30 Jan / 28

57 Neutron Decay Measurements: Nab and abba The Spallation Neutron Source Overview of SNS and FnPB D. Počanić (UVa) Research Talk 30 Jan / 28

58 Neutron Decay Measurements: Nab and abba Overview of SNS and FnPB The Fundamental Neutron Physics Beamline D. Poc anic (UVa) Research Talk 30 Jan / 28

59 Neutron Decay Measurements: Nab and abba The Nab Collaboration Overview of SNS and FnPB Arizona State University R. Alarcon, S. Balascuta, IKEP Karlsruhe F. Glück, University of Kentucky C. Crawford, Los Alamos Nat l. Lab. A. Klein, W.S. Wilburn, University of Manitoba M.T. Gericke, S.A. Page, Univ. of New Hampshire J.R. Calarco, F.W. Hersman, North Carolina State U. A. Young, Oak Ridge Nat l. Lab. J.D. Bowman, T.V. Cianciolo, S.I. Penttilä, K.P. Rykaczewski, G.R. Young, Univ. of South Carolina V. Gudkov, University of Sussex J. Byrne, University of Tennessee G.L. Greene, R.K. Grzywacz, University of Virginia L.P. Alonzi, S. Baeßler, M.A. Bychkov, E. Frlež, A. Palladino, D. Počanić. University of Winnipeg J. Martin. Home page D. Počanić (UVa) Research Talk 30 Jan / 28