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Author |
BABAR Collaboration (Lees, J.P. et al); Martinez-Vidal, F.; Oyanguren, A.; Villanueva-Perez, P. |

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Title |
Search for a low-mass scalar Higgs boson decaying to a tau pair in single-photon decays of Y(1S) |
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Journal Article |
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Year |
2013 |
Publication |
Physical Review D |
Abbreviated Journal |
Phys. Rev. D |
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Volume |
88 |
Issue |
7 |
Pages |
071102 - 8pp |
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Abstract |
We search for a low-mass scalar CP-odd Higgs boson, A(0), produced in the radiative decay of the upsilon resonance and decaying into a tau(+)tau(-) pair: Y(1S) -> gamma A(0). The production of Y(1S) mesons is tagged by Y(2S) -> pi(+)pi(-) Y(1S) transitions, using a sample of (98.3 +/- 0.9) x 10(6) Y(2S) mesons collected by the BABAR detector. We find no evidence for a Higgs boson in the mass range 3: 5 <= m(A)0 <= 9: 2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Y(3S) decays, setting limits on the coupling of A(0) to the b (b) over bar quarks in the range 0.09-1.9. Our measurements improve the constraints on the parameters of the next-to-minimal-supersymmetric Standard Model and similar theories with low-mass scalar degrees of freedom. |
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Address |
[Lees, J. P.; Poireau, V.; Tisserand, V.] Univ Savoie, CNRS IN2P3, Lab Annecy Le Vieux Phys Particules, F-74941 Annecy Le Vieux, France |
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Amer Physical Soc |
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English |
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ISSN |
1550-7998 |
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WOS:000326039300001 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1632 |
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Author |
Bernabeu, J.; Mavromatos, N.E.; Villanueva-Perez, P. |

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Title |
Consistent probabilistic description of the neutral Kaon system |
Type |
Journal Article |
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Year |
2013 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
724 |
Issue |
4-5 |
Pages |
269-273 |
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Abstract |
The neutral Kaon system has both CF violation in the mass matrix and a non-vanishing lifetime difference in the width matrix. This leads to an effective Hamiltonian which is not a normal operator, with incompatible (non-commuting) masses and widths. In the Weisskopf-Wigner Approach (WWA), by diagonalizing the entire Hamiltonian, the unphysical non-orthogonal “stationary” states K-L,K-S are obtained. These states have complex eigenvalues whose real (imaginary) part does not coincide with the eigenvalues of the mass (width). matrix. In this work we describe the system as an open Lindblad-type quantum mechanical system due to Kaon decays. This approach, in terms of density matrices for initial and final states, provides a consistent probabilistic description, avoiding the standard problems because the width matrix becomes a composite operator not included in the Hamiltonian. We consider the dominant decay channel to two pions, so that one of the Kaon states with definite lifetime becomes stable. This new approach provides results for the time dependent decay rates in agreement with those of the WWA. |
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[Bernabeu, J.; Villanueva-Perez, P.] Univ Valencia, Dept Theoret Phys, E-46100 Valencia, Spain, Email: pablo.villanueva@uv.es |
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Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Notes |
WOS:000322358500011 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1526 |
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Permanent link to this record |
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Author |
BABAR Collaboration (Lees, J.P. et al); Bernabeu, J.; Martinez-Vidal, F.; Oyanguren, A.; Villanueva-Perez, P. |

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Title |
Observation of Time-Reversal Violation in the B-0 Meson System |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
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Volume |
109 |
Issue |
21 |
Pages |
211801 - 8pp |
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Abstract |
Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B-0 or (B) over bar (0)), and J/psi K-L(0) or c (c) over barK(S)(0) final states (referred to as B+ or B-), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, (B) over bar (0) -> B- and B- -> (B) over bar (0), as a function of the time difference between the two B decays. Using 468 X 10(6) B (B) over bar pairs produced in Y(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding Delta S-T(+) = -137 +/- 0.14(stat) +/- 0.06(syst) and Delta S-T(-) = 1.17 +/- 0.18(stat) +/- 0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation. |
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Address |
[Lees, J. P.; Poireau, V.; Tisserand, V.] Univ Savoie, CNRS, IN2P3, LAPP, F-74941 Annecy Le Vieux, France |
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Thesis |
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Publisher |
Amer Physical Soc |
Place of Publication |
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Editor |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Edition |
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ISSN |
0031-9007 |
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Notes |
WOS:000311283800001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1220 |
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Permanent link to this record |