共查询到20条相似文献,搜索用时 31 毫秒
1.
Z.J. Xiao W.J. Li L.B. Guo G.R. Lu 《The European Physical Journal C - Particles and Fields》2001,18(4):681-709
Based on the low energy effective Hamiltonian with generalized factorization, we calculate the new physics contributions
to the branching ratios and CP-violating asymmetries of the two-body charmless hadronic decays from the new strong and electroweak penguin diagrams in the topcolor-assisted technicolor (TC2) model. The top-pion penguins
dominate the new physics corrections, and both new gluonic and electroweak penguins contribute effectively to most decay modes.
For tree-dominated decay modes , etc. the new physics corrections are less than 10%. For decays , etc. the new physics enhancements can be rather large (from to ) and are insensitive to the variations of and within reasonable ranges. For the decays and is strongly dependent: varying from to in the range of –. The new physics corrections to the CP-violating asymmetries vary greatly for different B decay channels. For five measured CP asymmetries of the decays, is only about 20% and will be masked by large theoretical uncertainties. The new physics enhancements to interesting decays are significant in size (), insensitive to the variations of the input parameters and hence lead to a plausible interpretation for the unexpectedly
large decay rates. The TC2 model predictions for branching ratios and CP-violating asymmteries of all fifty-seven decay modes are consistent with the available data within one or two standard deviations.
Received: 18 August 2000 / Revised version: 22 October 2000 / Published online: 5 February 2001 相似文献
2.
We investigate the b-u skewed parton distributions (SPDs) for transitions and determine the contributions from several sources (overlaps of soft light-cone wave functions, quark-antiquark
annihilations and meson resonances). The transition form factors, which are relevant in exclusive semi-leptonic and non-leptonic B-decays, are obtained by integrating the b-u SPDs over the momentum fraction x. A phenomenological determination of the relevant parameters allows us to predict the form factors and to obtain the branching
ratios for semi-leptonic decays.
Received: 18 June 1999 / Revised version: 8 September 1999 / Published online: 3 November 1999 相似文献
3.
P. Urban 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):551-553
We use the light-cone sum rule technique to calculate the contribution of the gluonic penguin operator O
8g
to the decay of the B-meson to two pions. Leading-order perturbative and non-perturbative corrections are included, corresponding to hard and soft exchanged gluons, respectively. While the overall contribution of this operator to the decay is small as expected before, we find that the so-called soft-gluon part of this contribution is of the order of the hard-gluon one. This implies that the inclusion of soft gluons in the calculation of
matrix elements may be important.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.25.Hw Hadronic decays of mesons: Decays of bottom mesons - 11.55.Hx Sum rules 相似文献
4.
X.-G. He 《The European Physical Journal C - Particles and Fields》1999,9(3):443-448
Several methods proposed to measure the angle in the KM unitarity triangle assumed that the tree contribution to is purely due to annihilation contributions and is negligibly small. This assumption has to be tested in order to have a
correct interpretation of the experimental data. In this paper we show that using SU(3) symmetry, the smallness of the tree
contribution can be tested in a dynamic model-independent way. We also derive several relations between CP violating rate differences for decays without assuming the smallness of the annihilation contributions. These relations provide important tests for the
standard model of CP violation.
Received: 5 January 1999 / Revised version: 4 March 1999 / Published online: 18 June 1999 相似文献
5.
S. Fajfer P. Singer J. Zupan 《The European Physical Journal C - Particles and Fields》2003,27(2):201-218
We present a calculation of the rare decay modes and in the framework of the standard model. For the short distance part we have derived QCD corrections to the Wilson coefficients
involved, including C9. The latter is found to be strongly suppressed by the corrections, leading to diminished values for the branching ratios in the 10-10 range. Within SM the exclusive decays are dominated by long distance effects. Non-resonant contributions are estimated using
heavy quark and chiral symmetries to be at the level of , compared to the contributions arising from , with . The total SM branching ratio is predicted to be in the range (1-. We also consider contributions coming from MSSM with and without R parity conservation. The effects from MSSM are significant only for the R parity violating case. Such contributions enhance the branching ratio to , based on appropriately allowed values for C9 and C10. This selects as a possible probe of new physics.
Received: 25 October 2002 / Published online: 24 January 2003 相似文献
6.
We study the implications of the recently improved upper limits on the branching ratios for the decays , expressed as . We work out the constraints that the current bound on implies on the parameters of the quark mixing matrix in the standard model (SM). Using the present profile of the unitarity
triangle, we predict this ratio to lie in the range (at 95% C.L.), with the central value . We also work out the correlations involving , the isospin-violating ratio , and the direct CP-violating asymmetry in decays in the SM, in the minimal supersymmetric extension of the SM (MSSM), and in an extension of the MSSM involving an
additional flavor-changing structure in transitions.
Received: 19 August 2002 / Published online: 18 October 2002
RID="a"
ID="a" e-mail: ali@mail.desy.de
RID="b"
ID="b" e-mail: lunghi@mail.desy.de 相似文献
7.
Charmless hadronic decays of B mesons to a vector meson (V) and a tensor meson (T) are analyzed in the frameworks of both flavor SU(3) symmetry and generalized factorization. We also make comments on B decays to two tensor mesons in the final states. Certain ways to test the validity of the generalized factorization are proposed,
using decays. We calculate the branching ratios and CP asymmetries using the full effective Hamiltonian including all the penguin operators and the form factors obtained in the non-relativistic quark model of Isgur, Scora, Grinstein and Wise.
Received: 6 July 2001 / Revised version: 8 October 2001 / Published online: 7 December 2001 相似文献
8.
A search for patterns in the numerous B-decay modes now available is necessary in order to test the Cabibbo-Kobayashi-Maskawa theory of CP-violation. In particular, the well-structured pattern of
branching ratios may lead to a quantized spectrum for direct CP-asymmetries, providing in this way a rather unique opportunity to discriminate between hadronic final state interaction models.Arrival of the final proofs: 25 June 2003 相似文献
9.
We present a general parametrization of , and , decays, taking into account both electroweak penguin and rescattering effects. This formalism allows – among other things
– a generalized implementation of the strategies that were recently proposed by Neubert and Rosner to probe the CKM angle
with the help of , decays. In particular, it allows us to investigate the sensitivity of the extracted value of to the basic assumptions of their approach. We find that certain rescattering processes may have an important impact and
emphasize that additional hadronic uncertainties may be due to non-factorizable SU(3)-breaking effects. The former can be controlled by using SU(3) flavour symmetry arguments and additional experimental information provided by modes. We propose a new strategy to probe the angle with the help of the neutral decays , , which is theoretically cleaner than the , approach. Here rescattering processes can be taken into account by just measuring the CP-violating observables of the decay
. Finally, we point out that an experimental analysis of modes would also be very useful to probe the CKM angle , as well as electroweak penguins, and we critically compare the virtues and weaknesses of the various approaches discussed
in this paper. As a by-product, we point out a strategy to include the electroweak penguins in the determination of the CKM
angle from decays.
Received: 14 June 1999 / Published online: 28 September 1999 相似文献
10.
We study two-body charmless hadronic decays of B mesons to a pseudoscalar meson (P) and a tensor meson (T) in the frameworks of both flavor SU(3) symmetry and generalized factorization. Certain ways to test the validity of the
generalized factorization are proposed, based on the flavor SU(3) analysis. We present a set of relations between a flavor
SU(3) amplitude and the corresponding amplitude in the generalized factorization which bridge both approaches in decays. The branching ratios and CP asymmetries are calculated using the full effective Hamiltonian including all the penguin operators and the form factors obtained in the non-relativistic quark model of Isgur, Scora, Grinstein and Wise. We identify
the decay modes in which the branching ratios and CP asymmetries are expected to be relatively large.
Received: 6 July 2001 / Revised version: 8 October 2001 / Published online: 30 November 2001 相似文献
11.
We study B(s)→φρ decays in a perturbative QCD approach based on kT factorization. In this approach, we calculate factorizable and non-factorizable contributions, there are no annihilation contributions due to quark content. We get the branching ratios and polarization fractions for B(s)→φρ decays. Our predictions are consistent with the current experimental data. 相似文献
12.
Cirigliano V. Ecker G. Neufeld H. Pich A. 《The European Physical Journal C - Particles and Fields》2004,33(3):369-396
We perform a complete analysis of isospin breaking in
amplitudes in chiral perturbation theory, including both strong isospin violation (
) and electromagnetic corrections to next-to-leading order in the low-energy expansion. The unknown chiral couplings are estimated at leading order in the 1/Nc expansion. We study the impact of isospin breaking on CP conserving amplitudes and rescattering phases. In particular, we extract the effective couplings g8 and g27 from a fit to
branching ratios, finding small deviations from the isospin-limit case. The ratio
measuring the
enhancement is found to decrease from
in the isospin limit to
in the presence of isospin breaking. We also analyze the effect of isospin violation on the CP violation parameter
, finding a destructive interference between three different sources of isospin violation. Within the uncertainties of large-Nc estimates for the low-energy constants, the isospin violating correction for
is below 15%.Received: 21 November 2003, Published online: 4 February 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain) 相似文献
13.
Jian-Feng Cheng Dong-Sheng Du Cai-Dian Lü 《The European Physical Journal C - Particles and Fields》2006,45(3):711-720
We investigate the branching ratios and direct CP-asymmetries of the
and
decays in the PQCD approach. All the diagrams with emission topology or annihilation topology are calculated strictly. A
branching ratio of 10-6 and 10-7 for
and
decay is predicted, respectively. Because of the different weak phase and strong phase from penguin operator and two kinds
of tree operator contributions, we predict a possible large direct CP-violation:
and
when γ = 55°, which can be tested in the coming LHC.
PACS:
13.25.Hw, 12.38.Bx 相似文献
14.
We calculate the CP violating effects in the top quark semi-leptonic three body decays induced by the supersymmetric CP-odd phase of the top squark trilinear soft breaking term . The light top squark mass is assumed to be close to the top quark mass, . The CP conserving phase is provided by the and cut. We find that the partial rate asymmetry is on the 0.1% level. In the most favorable parameter region the decay rate
asymmetry can reach up to 0.55%.
Received: 19 April 1999 / Published online: 16 November 1999 相似文献
15.
Eri Asakawa Jun-ichi Kamoshita Akio Sugamoto Isamu Watanabe 《The European Physical Journal C - Particles and Fields》2000,14(2):335-345
We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process
at the energy around the mass poles of the Higgs bosons. It is found that interference between H and A with small mass gap, as well as the ones between Higgs bosons and continuum, contributes to the cross section, if the photon
beams are polarized and if we observe the helicity of the top quarks. It is demonstrated in the framework of the minimal supersymmetric
extension of the standard model that the H and A contributions can be sizable at future colliders for small values of . The methods to measure the CP-parity of the Higgs boson are also presented. The statistical significance of detecting the Higgs signals and measuring the
Higgs CP-parity is evaluated.
Received: 16 December 1999 / Revised version: 30 January 2000 / Published online: 6 April 2000 相似文献
16.
C.-D. Lü 《The European Physical Journal C - Particles and Fields》2002,24(1):121-126
The rare decay can occur only via annihilation-type diagrams in the standard model. We calculated this decay in the perturbative QCD approach
with Sudakov resummation. We found that the branching ratio of is of order ; this may be measured in the near future by the KEK and SLAC B factories. The small branching ratio predicted in the standard model makes this channel sensitive to new physics contributions.
Received: 16 January 2002 / Published online: 5 April 2002 相似文献
17.
S. Descotes N.H. Fuchs L. Girlanda J. Stern 《The European Physical Journal C - Particles and Fields》2002,24(3):469-483
The recently published E865 data on charged decays and phases are reanalyzed to extract values of the two S-wave scattering lengths, of the subthreshold parameters and , of the low-energy constants and as well as of the main two-flavour order parameters: and in the limit taken at the physical value of the strange quark mass. Our analysis is exclusively based on direct experimental information
on phases below 800 MeV and on the new solutions of the Roy equations by Ananthanarayan et al. The result is compared with the
theoretical prediction relating 2a
0
0-5a
0
2 and the scalar radius of the pion, which was obtained in two-loop Chiral Perturbation Theory. A discrepancy at the 1- level is found and commented upon.
Received: 11 December 2001 / Revised version: 28 March 2002 / Published online: 7 June 2002 相似文献
18.
S.Y. Choi M. Drees J.S. Lee J. Song 《The European Physical Journal C - Particles and Fields》2002,25(2):307-313
Decays into neutralinos and charginos are among the most accessible supersymmetric decay modes of Higgs particles in most
supersymmetric extensions of the standard model. In the presence of explicitly CP violating phases in the soft breaking sector of the theory, the couplings of Higgs bosons to charginos and neutralinos are
in general complex. Based on a specific benchmark scenario of CP violation, we analyze the phenomenological impact of explicit CP violation in the minimal supersymmetric standard model on these Higgs boson decays. The presence of CP violating phases could be confirmed either directly through the measurement of a CP odd polarization asymmetry of the produced charginos and neutralinos, or through the dependence of CP even quantities (branching ratios and masses) on these phases.
Received: 18 April 2002 / Published online: 26 July 2002 相似文献
19.
L. G. Landsberg 《Physics of Atomic Nuclei》2002,65(10):1749-1770
A new experiment CKM is accepted by Fermilab for a very sensitive study of rare kaon decay $K^ + \to \pi ^ + \nu \bar \nu $ on an intense separated kaon beam. The high quality of the beam and CKM setup make it possible to perform an important set of other kaon-decay measurements in parallel with the main research program: (1) the search for new physics effects beyond the Standard Model (search for new P, S, T interactions and lepton flavor violation in kaon decays); (2) further search for direct CP violation in charged kaon decays; (3) study of low-energy hadron physics in pure conditions of decay processes (K + → π + l + l ?; ππlν l; π 0 γγ, etc.). The expected results of these studies are compared with other experimental programs. 相似文献
20.
C.-S. Huang W. Liao Q.-S. Yan S.-H. Zhu 《The European Physical Journal C - Particles and Fields》2002,25(1):103-111
The Higgs boson mass spectrum and couplings of the neutral Higgs bosons to the fermions are worked out in a CP spontaneously broken two-Higgs doublet model in the large case. The differential branching ratio, forward-backward asymmetry, CP asymmetry and lepton polarization for are computed. It is shown that the effects of neutral Higgs bosons are quite significant when is large. Especially, the CP violating normal polarization can be as large as several percents.
Received: 15 October 2001 / Revised version: 5 March 2002 / Published online: 26 July 2002 相似文献