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Recent results from BABAR

Recent results from BABAR. Ida Peruzzi Laboratori Nazionali di Frascati dell’INFN & Università di Perugia on behalf of the BABAR Collaboration. THE BABAR DETECTOR. PEP-II : THE SLAC B-FACTORY. OUTLINE. Y(4S) DATA: FIRST MEASUREMENT OF T VIOLATION Y(3S) AND Y(2S) DATA:

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Recent results from BABAR

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  1. Recent results from BABAR Ida Peruzzi LaboratoriNazionali di Frascatidell’INFN & Università di Perugia on behalf of the BABAR Collaboration

  2. THE BABAR DETECTOR Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  3. PEP-II : THE SLAC B-FACTORY Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  4. OUTLINE • Y(4S) DATA: • FIRST MEASUREMENT OF T VIOLATION • Y(3S) AND Y(2S) DATA: • SEARCH FOR A LIGHT CP ODD HIGGS • SEARCH FOR A DARK HIGGS AND A DARK PHOTON Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  5. TESTING THE FUNDAMENTAL SYMMETRIES CP: G( i f) vsG(if ) t  t T: G( i f) vsG( f  i ) t  -t CPT: G( i f) vsG(fi ) t  -t THEORY REQUIRES CPT TO BE AN EXACT SYMMETRY ! CP violation has been experimentally proven in K and B mesons INDIRECT PROOF OF T VIOLATION Can we test T independent of CPT? CPLEAR (Phys. Lett. B444, 43 (1998) G( K0 K0) ≠G( K0 K0 ) CP or T VIOLATION ? B-factories (et al.) overwhelming evidence! G( B0 K+p- ) ≠ G(B0 K-p+ ) G( B0 J/YKs) ≠ G(B0 J/YKs) CP VIOLATION ! Examples: THE PROBLEM: HOW TO REVERT A B0 DECAY ? Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  6. EPR: THE QUANTUM ENTANGLEMENT The Y(4S) decays to a pair of B mesons in a coherent L=1 antisymmetric quantum state. Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  7. Decay rates and CP asymmetry for SM: if C=0 , S= sin(2f), f = a, b, g depending on b transition J/Y KS hf=-1 C=0 , f= b J/YKL hf= +1 Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  8. TIME REVERSAL VIOLATION : THE IDEA Einstein-Podolsky-Rosen entanglement applies to any pair of orthogonal states! The same entangled state of the system can be rewritten CP defined via the decay to a J/Y KS (CP=-1) or J/Y KL (CP=+1) { decay to a J/Y KS (CP=-1) tags the other B as CP+ (B+) decay to a J/YKL(CP=+1) tags the other B as CP-(B-) CP Tag: Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  9. REVERSE PROCESSES Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  10. TAGGED J/YKS AND J/YKL EVENTS IN THE SM: 4 INDEPENDENT COMPARISONS EACH FOR CP, T , CPT Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  11. RAW T ASYMMETRIES Points: data Red line: projection of fit with TRV Blue line: projection of fit without TRV Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  12. FIT RESULTS Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  13. STATISTICAL SIGNIFICANCE CPT violation Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  14. A LOW MASS NEUTRAL HIGGS? … it arises in several beyond SM scenarios ! • The MSSM model introduces 5 more Higgs doublets: h (CP-even light), H (CP-even, heavy), A (CP-odd) , H± (charged partners) • The NMSSM, proposed as the smallest extension to the MSSM in order to solve EW scale fine tuning, adds new Higgs fields: • The lightest CP odd is a singlet which mixes with the A • Models are not excluded by LEP constrains if: IF this is the case, the A0 can be produced by radiative decays of Y(nS). Y(nS)  g A0 The BR depends on the A0 mass, cosqA, tanβ (the ratio of the vacuum expectation values of the up and down type Higgs doublets), and m, (another supersymmetry parameter). IFthe BR is high enough, BABAR could find a signal, or restrict significantly the phase space Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  15. BABAR SEARCHES FOR LIGHT CP-ODD HIGGS Search for the T(1S) decay: 15 Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  16. SEARCH FOR Y(1S)gA0 ,A0 m+m- • Event selection: • 4 charged tracks + a photon • 2 pions and at least one muon identified • Eg >200 MeV (in the CM) • Vertex constrain and Kinematical consistency with the decay chain: • Y(2S) , Y(3S)p+ p- Y(1S) gm+m- • The imposed constraints improve the resolution of the di-muon invariant mass to be less than 10 MeV/c2. FROM Y(2S), Y(3S) DATA SAMPLES Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  17. LIMITS ON THE BR(Y(1S)gA0 )xBR(A0 m+m- ) Combined • 4585 A0 mass hypotheses • 18% of pseudo-experiments see 3.62 s • NO SIGNAL ! Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  18. SEARCH FOR A0t+t- arXiv:1210.5669 Data set: Y(2S) Y(1S) identified as recoil mass against the pion pair, and the A0 as recoil mass against the photon: • Require both taus to decay to a single track, at least one of which a lepton. • Low energy photon background is very different • Optimize selection criteria separately for • 3.6 < MA < 8.0 GeV/c2and 8.0 < MA< 9.2 GeV/c2 • Neural Net to select the t+t-. • Look for a peak in mass recoiling against the π+π- and the monochromatic photon. • 201 different A0 mass hypotheses tested • largest fluctuation found: 3.0 s • 7.5% of pseudo-experiments have a  3.0σ fluctuation: NO SIGNAL ! Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  19. COMBINED LIMIT ON THE A0 COUPLING FROM Y(nS)gA0 , A0 t+t- Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  20. SEARCH FOR A0s s , g gPhys.Rev. D88 (2013) 031701 Data set: Y(2S)  108 events Search for Y(2S)  p+p- Y(1S) • 17.6x106 Y(1S) decays, very clean sample! • 26 channels researched • A0s s sample is the subset of A0gg decay channels that include 2 or 4 kaons • Require the hadronic system and a photon to be consistent with the mass of an ϒ(1S) • Mass spectrum scanned in 10MeV/c2 steps from 0.5GeV to 9.0GeV/c2 • Define a mass window, centered on each hypothesis A0mass. • Mass windows widths and efficiencies are determined by MC for a number of values and interpolated for the others. Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  21. RESULTS • No A0 signal found! • it would appear as a narrow peak in the invariant mass • 90% UL derived on the product of BRs Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  22. THE DARK SECTOR • Theastrophysical evidence for dark matter is now overwhelming • Models introducing a new ‘dark’ force mediated by a light gauge boson (MeV-GeV scale) have been proposed to explain the observations of PAMELA, FERMI, AMS-02, DAMA, CREST,... • Wimp-like TeV-scale dark matter particles can annihilate into pairs of dark bosons, which subsequently decay to lepton pairs (protons are kinematically forbidden) or scatter on nucleons via dark boson exchange. • Many theories beyond the SM include dark sectors The possibility of light hidden sector is poorly constrained and worth exploring. • Low-energy high-luminosity e+e- colliders offer a low background environment to search for light hidden sector(s) and eventually probe their structure 22 Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  23. A DARK PHOTON? Standard Model Fmn Dark Sector GD U(1)D Bmn U(1)gU(1)D DLmix ~ e FmnBmn • Dark sector with a U(1)D gauge group • New gauge boson: dark photon A' with O(MeV - GeV) mass • Interaction with SM via kinetic mixing • eFmnBm • with a mixing strength e • The dark photon couples to SM fermions with a charge ee • Theory favors e between 10-5– 10-3, though models can accommodate lower values Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  24. POSSIBLE SEARCHES AT B FACTORIES Search for dark photon e+e-→ gA' , A' → e+e-, μ+μ-, π+π- e+e- → gA' , A' → invisible Search for dark boson(s) e+e-→ A'* → W'W'' e+e-→ gA' → W'W'' Search for dark Higgs boson e+e-→ h' A' , h' → A' A' e+e-→ h' A' , h' → invisible THIS TALK …more ideas welcome! Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  25. LIMITS ON e2=a’/a BABAR limits on A0 m+m- reinterpreted as bounds on α' / α = ε2 (E. Essig et al. Phys.Rev. D80 (2009) 015003 ) Caution: the light Higgs is a scalar, the dark photon is a vector the efficiency will be different Current limits on e2=a’/a Searches for dark photon being extended to full data set Expect significant improvement: exclude almost all the “g-2” preferred region. Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  26. A DARK HIGGS? • The idea is that a dark photon mass is generated via the Higgs mechanism, adding a dark Higgs boson h′ to the theory. • A minimal scenario has a single dark photon and a single dark Higgs boson. • In many generic models, the dark Higgs mass is also at the MeV/GeV scale • The mass hierarchy between these two particles is not constrained, and the dark Higgs boson could be light (at the GeV scale). • The Higgsstrahlungprocess: • e+e- → A'* → h' A' , h' → A’ A’ • is very interesting to search for, as it is only suppressed by ε2 and is expected to have a very small background. gD dark sector coupling Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  27. DARK HIGGS SEARCH The total (516 fb-1) data set has been used to search for the process: e+e-→ h' A' , h' → A' A‘ exploring the mass range : 0.8 < mh′ < 10.0 GeV 0.25 < mA′ < 3.0 GeV with the constraint: ( mh> 2 mA′ ) Hypotheses tested in sequence until a match is found: 6μ, 4μ2e, 2μ4e, 6e, 4μ2π, 2μ2e2π, 4e2π, 2μ4π, 2e4π, 4μ +X, 2μ2e + X. Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  28. LIMITS ON HIGGSSTRAHLUNG CROSS SECTION • After the final selection we find a total of six events (none with 6 leptons. and consistent with calculated background) • 1 (4μ2π), 2 (2μ4π), 2 (2e4π) , 1 (4μ + X) • 3 entries for each event (3 possible assignment for h’ A’ A’ • The (mh′ , mA′ ) plane scanned in steps of 10MeV in both directions between • 0.8 < mh′ < 10 GeV 0.25 < mA′ < 3 GeV • Limits on each channel are then combined to extract 90% CL upper limits on cross sections: • typically 10 − 100 ab Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  29. LIMITS ON DARK FORCE COUPLING Substantial improvement over previous limits if a dark light Higgs exists in the mass range 3-7 GeV! Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  30. SUMMARY More than 5 years after the end of data taking, BABAR is still producing new results! • TRV has been measured for the first time, independent of CPV and CPT assumptions • Exciting possibilities offered by Y(2S) and Y(3S) data to look for new Physics • No light CP-odd Higgs so far, but significant limits in several decay channels • Searches for dark matter (dark photon, dark light Higgs) will soon be extended to full data set; if still no signal found, the parameter space will be considerably reduced • Many analyses going on, both new ideas or extensions of previous work. • You will keep hearing from BABAR for a while… • The next generation B-Factory will allow more in depth tests of the models and, hopefully, provide additionalexciting discoveries, so we look forward to • BELLE II AT SUPER-KEKB Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  31. BACKUP SLIDES Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  32. ANALYSIS PROCEDURE IN A NUT SHELL • Reconstruct final state : use (resolution3MeV) and • (resolution 10-50 MeV). For KL only the direction is measured, need to constraint at B mass. Reduce u,d,s,c continuum background with topological cuts. Determine B decay vertex (z2) • Determine B flavor: inclusive tagging looking at remainder of the event. The sign of high momentum leptons or Kaons, slow pions from D* etc ; all information feed to a neural network to get flavor of other B (efficiency  30%). Determine tag decay vertex (z1) • Determine signed time difference to place event in the right category. • Perform global fit of asymmetry, taking into account wrong tag probability, error on time • difference measurement, different kind of backgrounds, detector effects, etc. • Obtain S and C coefficients as a result of the fit, and compute systematic error. Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  33. CP RAW ASYMMETRIES Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  34. CPT RAW ASYMMETRIES Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  35. FIT RESULTS FOR AND Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

  36. EXPECTED A0 DECAYS R. Dermisek and J. F. Gunion, Phys. Rev. D 81, 075003 (2010). Branching ratios for A0 decays depend on its mass and the value of tan β A0ss For up and down type fermion A0tt A0mm A0gg A0cc Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013 36

  37. LIMITS ON PARAMETERS SPACE Ida Peruzzi, International Conference on New Frontiers in Physics - Kolymbari, Crete, Greece - Aug31.2013

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