共查询到20条相似文献,搜索用时 15 毫秒
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R. Fleischer S. Recksiegel F. Schwab 《The European Physical Journal C - Particles and Fields》2007,51(1):55-61
Recently, we have seen interesting progress in the exploration of CP violation in B0
d→π+π-: the measurements of mixing-induced CP violation by the BaBar and Belle collaborations are now in good agreement with each
other, whereas the picture of direct CP violation is still unclear. Using the branching ratio and direct CP asymmetry of B0
d→π-K+, this situation can be clarified. We predict , which favours the BaBar result, and we extract γ=(70.0+3.8
-4.3)°, which agrees with the unitarity triangle fits. Extending our analysis to other B→πK modes and B0
s→K+K- with the help of the SU(3) flavour symmetry and plausible dynamical assumptions, we find that all observables with colour-suppressed
electroweak penguin contributions are measured to be in excellent agreement with the standard model. As far as the ratios
Rc,n of the charged and neutral B→πK branching ratios are concerned, which are sizeably affected by electroweak penguin contributions,
our standard-model predictions have almost unchanged central values but significantly reduced errors. Since the new data have
moved quite a bit towards these results, the “B→πK puzzle” for the CP conserving quantities has been significantly reduced.
However, the mixing-induced CP violation of B0
d→π0KS does look puzzling; if confirmed by future measurements, this effect could be accommodated through a modified electroweak
penguin sector with a large CP violating new-physics phase. Finally, we point out that the established difference between
the direct CP asymmetries of B±→π0K± and Bd→π∓K± appears to be generated by hadronic and not by new physics. 相似文献
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D. Delepine J. L. Lucio M. C. A. Ramírez 《The European Physical Journal C - Particles and Fields》2006,45(3):693-700
We analyze the
and B–,0 → f0K–,0 decays and show that a consistent phenomenological picture can be obtained within the factorization approximation. In this
approach the O6 operator provides the dominant contributions to the suppressed channel
. An estimate of the annihilation form factor using perturbative QCD indicates that this contribution is not negligible, moreover
interference with other penguin contributions includes a free parameter since the phase of the annihilation amplitude is not
determined. Assumptions based on SU(2) isospin symmetry provide relations between different B decays involving one scalar and one pseudoscalar meson. 相似文献
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Radial (L=0) excitations ofp- and π-mesons are considered in the framework of the quark model. The experimentally observed statesρ′ (1220) andρ″ (1560) are identified with the first and second radial excitations of thep-meson. Within the relativistically generalized model of spontaneous production of a \(q\bar q\) pair from vacuum we explain the dominant (ρ′ →ωπ;ρ″ →ω2π) modes of strong decays of these resonances and find nondominant modes (ρ ′ 2π;ρ″ →ωπ) to be suppressed. An estimation is given for masses of analogous excitations of the pion and partial widths of their decays. 相似文献
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《Physics letters. [Part B]》1987,189(3):363-368
The decays KL,S → π0γγ are calculated within the framework of chiral perturbation theory. The amplitude for KL → π0γγ is found to be finite at the one-loop level yielding a branching ratio of 6.8 × 10−7. The decay spectra of both decays are very characteristic and provide good tests of the effective chiral symmetry realization of the standard model. 相似文献
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The implications of the model with a SU(2)-singlet up-type quark, heavy enough not to be produced at the LHC, namely, the contribution of the new quark to the branching ratios of the K → πν $ \bar \nu $ , B → πν $ \bar \nu $ , and B → Kν $ \bar \nu $ decays are investigated. It is shown that the deviation from the Standard Model can be up to 10% in the case of a 5-TeV quark. Precise measurements of these branching ratios in future experiments will allow for the observation of the contributions of the new quark or to impose stronger constraints on its mass. 相似文献
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M. K. Volkov M. Nagy A. N. Ivanov N. I. Troitskaya 《Czechoslovak Journal of Physics》1989,39(11):1256-1262
In the special type of the quark model we obtain the ratio=h
A/hV of the axial (hA) and vector (hV) form factors for the decays – e– ¯ve and K– e–¯ve different from unity. The low-energy theorem, relating the electric polarizability of the charged pion with the ratio, is analyzed. It is shown that
< 1 corresponds to , calculated by accounting the contribution of the scalar meson(700) into the amplitude of the Compton effect on the pion. In the absence of the(700) contribution we have=1.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday. 相似文献
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We estimate the rates ofB 0 decays into neutral charmed final states \(B^0 \to \overline {D^{ * 0} } \gamma ,B^0 \to \overline {D^{ * 0} } \pi ^0 ,B^0 \to \overline {D^0 } \pi ^0 ,B^0 \to \overline {D^0 } \omega \) , by considering factorizable, vector meson dominance and long distance contributions. We also discuss the role of these decay modes as a source of background events in the search for exclusiveb→sγ transitions in very high energy experiments, e.g. at LEP. 相似文献
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Robert Fleischer 《The European Physical Journal C - Particles and Fields》1999,6(3):451-470
A general parametrization of the B
+ → π
+
K
0 and B
d
0 → π
−
K
+ decay amplitudes is presented. It relies only on the isospin symmetry of strong interactions and the phase structure of the
Standard Model and involves no approximations. In particular, this parametrization takes into account both rescattering and
electroweak penguin effects, which limit the theoretical accuracy of bounds on γ arising from the combined B
+- → π
+-
K, B
d
→ π
∓
K
± branching ratios. Generalized bounds making also use of the CP asymmetry in the latter decay are derived, and their sensitivity
to possible rescattering and electroweak penguin effects is investigated. It is pointed out that experimental data on B
± → K
±
K allow us to include rescattering processes in these bounds completely, and an improved theoretical treatment of electroweak
penguins is presented. It is argued that rescattering effects may enhance the combined B
± → K
±
K branching ratio by a factor of O(10) to the 10−5 level, and that they may be responsible for the small present central value of the ratio of the combined B
d
→ π
∓
K
± and B
± → π
±
K branching ratios, which has recently been reported by the CLEO collaboration and, if confirmed, would exclude values of γ
within a large region around 90°. 相似文献
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Aaij R Abellan Beteta C Adeva B Adinolfi M Adrover C Affolder A Ajaltouni Z Albrecht J Alessio F Alexander M Alkhazov G Alvarez Cartelle P Alves AA Amato S Amhis Y Anderson J Appleby RB Aquines Gutierrez O Archilli F Arrabito L Artamonov A Artuso M Aslanides E Auriemma G Bachmann S Back JJ Bailey DS Balagura V Baldini W Barlow RJ Barschel C Barsuk S Barter W Bates A Bauer C Bauer T Bay A Bediaga I Belous K Belyaev I Ben-Haim E Benayoun M Bencivenni G Benson S Benton J Bernet R Bettler MO 《Physical review letters》2012,108(10):101601
A search is performed for the lepton number violating decay B+ → h- μ+ μ+, where h- represents a K- or a π-, using an integrated luminosity of 36 pb(-1) of data collected with the LHCb detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B+ → K- μ+ μ+) < 5.4×10(-8) and B(B+ → π- μ+ μ+) < 5.8×10(-8) are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively. 相似文献
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We analyzeK decays in the framework of Chiral Perturbation Theory. We study the different Dalitz plot distributions, trying to find regions whereo(p
6) contributions could be more easily detected. To fulfill this program we compute all theo(p
4) loop and counterterm contributions, finding a substantial agreement with the existing calculations and adding some small missing terms inK
S
+–.Work supported in part by the Human Capital and Mobility Program, EEC Contract N. CHRX-CT920026 相似文献
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《Physics letters. [Part B]》1997,415(4):452-462
A search for φ radiative decays has been performed using a data sample of about 2.0 million φ decays collected by the CMD-2 detector at VEPP-2M collider in Novosibirsk. From the selected e+e−→π+π−γ events the following results were obtained:B(φ→f0(980)γ)<1×10−4 for destructive andB(φ→f0(980)γ)<7×10−4 for constructive interference with the Bremsstrahlung process respectively,B(φ→γ→π+π−γ)<3×10−5 for Eγ>20 MeV,B(φ→ργ)<7×10−4. From the selected e+e−→μ+μ−γ eventsB(φ→μ+μ−γ)=(2.3±1.0)×10−5 has been obtained for Eγ>20 MeV. The upper limit on the P,CP-violating decay η→π+π− has also been placed:B(η→π+π−)<9×10−4. All upper limits are at 90% C.L. 相似文献
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Won E Ko BR Adachi I Aihara H Arinstein K Asner DM Aushev T Bakich AM Barberio E Bay A Bhardwaj V Bhuyan B Bischofberger M Bondar A Bozek A Bračko M Brodzicka J Browder TE Chang P Chen A Chen P Cheon BG Chilikin K Cho IS Cho K Choi SK Choi Y Dalseno J Danilov M Doležal Z Drásal Z Drutskoy A Eidelman S Fast JE Gaur V Gabyshev N Garmash A Goh YM Golob B Haba J Hara T Hayasaka K Hayashii H Horii Y Hoshi Y Hou WS Hsiung YB Hyun HJ Iijima T Inami K Ishikawa A Itoh R Iwabuchi M Iwasaki Y Iwashita T 《Physical review letters》2011,107(22):221801
We report the first observation of the doubly Cabibbo-suppressed decays D(+)→K(+)η((')) using a 791 fb(-1) data sample collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The ratio of the branching fractions of doubly Cabibbo-suppressed relative to singly Cabibbo-suppressed D(+)→π(+)η((')) decays are B(D(+)→K(+)η)/B(D(+)→π(+)η)=(3.06±0.43±0.14)% and B(D(+)→K(+)η')/B(D(+)→π(+)η')=(3.77±0.39±0.10)%. From these, we find that the relative final-state phase difference between the tree and annihilation amplitudes in D(+) decays, δ(TA), is (72±9)° or (288±9)°. We also report the most precise measurements of CP asymmetries to date: A(CP)(D(+)→π(+)η)=(+1.74±1.13±0.19)% and A(CP)(D(+)→π(+)η')=(-0.12±1.12±0.17)%. 相似文献
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《Physics Reports》2002,370(6):537-680
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Nishimura K Browder TE Adachi I Aihara H Arinstein K Aushev T Bakich AM Balagura V Barberio E Belous K Bhardwaj V Bischofberger M Bondar A Bozek A Bračko M Chang MC Chao Y Chen A Chen KF Chen P Cheon BG Chiang CC Cho IS Choi Y Dalseno J Danilov M Doležal Z Drutskoy A Eidelman S Gabyshev N Golob B Ha H Haba J Hara T Hayasaka K Hayashii H Horii Y Hoshi Y Hou WS Hyun HJ Iijima T Inami K Itoh R Iwabuchi M Iwasaki Y Joshi NJ Julius T Kang JH Kapusta P Kawai H Kawasaki T Kichimi H Kiesling C Kim HJ 《Physical review letters》2010,105(19):191803
We report a first measurement of inclusive B→Xsη decays, where Xs is a charmless state with unit strangeness. The measurement is based on a pseudoinclusive reconstruction technique and uses a sample of 657×10(6)BB pairs accumulated with the Belle detector at the KEKB e+e- collider. For MXs < 2.6 GeV/c2, we measure a branching fraction of [26.1±3.0(stat)-2.1+1.9(syst)-7.1+4.0(model)]×10(-5) and a direct CP asymmetry of ACP=-0.13±0.04-0.03+0.02. Over half of the signal occurs in the range MXs > 1.8 GeV/c2. 相似文献
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V. M. Aul’chenko R. R. Akhmetshin B. Sh. Banzarov L. M. Barkov N. S. Bashtovoi A. E. Bondar’ A. V. Bragin A. A. Grebenyuk D. N. Grigor’ev D. A. Epifanov A. S. Zaitsev F. V. Ignatov V. F. Kazanin S. V. Karpov I. A. Koop P. P. Krokovny A. S. Kuz’min I. B. Logashenko P. A. Lukin K. Yu. Mikhailov I. N. Nesterenko A. V. Otboev V. S. Okhapkin E. A. Perevedentsev A. S. Popov S. I. Redin A. A. Ruban N. M. Ryskulov A. L. Sibidanov V. P. Smakhtin I. G. Snopkov E. P. Solodov G. V. Fedotovich B. I. Khazin Yu. M. Shatunov B. A. Shvarts S. I. Eidel’man Yu. V. Yudin 《JETP Letters》2008,88(2):85-90
The ? → π+π?γγ and ? → π+π?η decays are sought in the experimental data obtained with the CMD-2 detector in the region of the ?-meson resonance. Upper limits ?(? → ππγγ)< 1.2 × 10?4 and ?(? → ππη) < 6.1 × 10?5 (both at a C.L. of 90%) are determined for the branching ratios of these decays. 相似文献
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N. N. Achasocv S. A. Devyanin G. N. Shestakov 《Zeitschrift fur Physik C Particles and Fields》1984,22(1):53-61
Carried out is the analysis of the new experimental data on theS-wave of the ππ→ \(K\bar K\) reaction in common with ππ→ππ one in the 1–1.6 Gev energy region. It is shown that new resonances are not required for the explanation of the data and for that the well-knownS * (980) and ε (1300–1400) resonances and their mixing only are enough. Once more confirmed is the possibility forS * (980) to be the \(qq\bar q\bar q\) from (9,0+) nonet of the \(qq\bar q\bar q\) mesons predicted by the MIT-bag model. Moreover, it is shown that the ε(1300–1400) resonance can be interpreted as a member of the second four-quark (9,0+)-nonet. We predict the bright manifestation of theS * and ε-resonances in the π+π? →ηη reaction. The analysis of the data shows that the ε-meson cannot be a pureSU (3)-singlet and therefore it cannot pretend to the role of the gluonium. Discussed is critically the Törnqvist's analysis for scalar mesons. 相似文献