Low momentum penguin loop contributions and the ΔI=1/2 rule

Contributions to the penguin diagram due to low loop momenta are considered. Using a chiral effective field theory including quarks coupling to pions and kaons, sizeable contributions fromu-quark loop momenta below the chiral symmetry breaking scale are found. Thus a previous result obtained within the bag model is confirmed. It is concluded that the low momentum penguin loop contributions seem to improve the theoretical understanding of the ΔI=1/2 rule.     

Electroweak penguin effects in charmless B ±,0→PP and PV decays

Using the next-to-leading order low energy effective Hamiltonian for |ΔB|=1, ΔC=ΔU=0 transitions, the contributions of electroweak penguin operators in charmless B ^±,0→PP and PV decays are estimated in the standard model. We find that, for some channels, the electroweak penguin effects can enhance or reduce the QCD penguin and/or tree level contributions by at least 30%, and can even play a dominant role.     

Perturbative QCD study on the photonic penguin contributions to the decay B\rightarrow K^* \gamma

Including corrections of order , we present an analysis of photonic penguin contributions to the decay in the perturbative QCD framework. Employing several models of the meson wave functions, we demonstrate that the corrections of are enhanced and will provide substantial contributions to the decay because of the meson wave function being sharply peaked (bound state effect). The numerical predictions for the corrections are about which depend on the non-perturbative inputs such as the meson wave functions and the -quark mass. Received: 8 July 1997 / Published online: 23 February 1998     

Effect of penguin operators in the B0 --> J/psiK0 CP asymmetry

Performing a fit to the available experimental data, we quantify the effect of long-distance contributions from penguin contractions in B0 --> J/psiK0 decays. We estimate the deviation of the measured S(CP) term of the time-dependent CP asymmetry from sin2beta induced by these contributions and by the penguin operators. We find deltaS is identically equal to S(CP)(J/psiK) - sin2beta = 0.000 +/- 0.012 ([-0.025, 0.024]@95% probability), an uncertainty much larger than previous estimates and comparable to the present systematic error quoted by the experiments at the B factories.     

Measurement of high-Q^{2} neutral-current e^+p deep inelastic scattering cross-sections at HERA

The neutral-current deep inelastic scattering differential cross-sections , for GeV, and , for , 2500 and 10000 GeV, have been measured with the ZEUS detector at HERA. The data sample of 47.7 pb was collected at a center-of-mass energy of 300 GeV. The cross-section, , falls by six orders of magnitude between and 40000 GeV. The predictions of the Standard Model are in very good agreement with the data. Complementing the observations of time-like contributions to fermion-antifermion annihilation, the data provide direct evidence for the presence of exchange in the space-like region explored by deep inelastic scattering. Received: 18 May 1999 / Published online: 3 August 1999     

相对论类空方程

根据Dirac类空自洽性条件的思想,通过引入类空因子定义了类空波函数.它的物理部分与Bethe-Salpeter波函数相一致.利用普适的相互作用核的重排技术,导出了对于束缚态和散射态的相对论类空方程,并且将它们推广到多粒子的情形.也得到了束缚态类空波函数的归一化条件和散射态类空方程的非齐次项的解.因此,建立起了相对论类空方程体系.     

Penguin effects induced by the two-Higgs-doublet model and charmlessB-meson decays

Nonstandard physical effects through the penguin diagram induced by the charged Higgs scalar contribution in the two-Higgs-doublet model are analysed. Since non-leptonicB-decay processes to final states consisting ofs+s+ \(\bar s\) are induced only through the penguin diagram they are important tests of such contributions. We compare these decays including the non-standard two-Higgs-doublet contribution with the standard model results, which arise from the magnetic gluon transistion term. The charged Higgs contribution can give a sizable enhancement to the branching fractions ofB-meson charmless decay.     

The scale-breaking contributions of the Pauli-Jordan functions and of the Feynman propagators

Proofs have been given that the underlying background of the scale-breaking contributions of the Pauli-Jordan functions and of the Feynman propagators is the existence of an energy dependent dispersion of the canonical scale dimension, respectively. The energy dependence of these dispersions can be established by taking into account the existence of the time dispersion, too. For the interacting fields the above functions are subject to the scale invariance restoration around the underlying proper-time dispersions, in so far as the short space-like space-time region is considered.     

Space-Like Form of Bethe-Salpeter Equation: Bound State

According to Dirac's principle, we apply the space-like consistency conditions in a relativistic theory to two-particle system and then define the space-Like wavefunctions through introducing a space-like factor, which is equivalent to Bethe-Salpeter wavefunction in physical content. The space-like form of Bethe-Salpeter equation of bound states is derived in terms of the universal rearranging technology of interaction kernel. Its advantages are of explicit Lorentz-covariant form and the difficulty of ghost states is automatically overcome. We also discuss the normalization condition of the space-like function.     

The rare K decays and Z^0 penguin contributions in the topcolor-assisted technicolor models

We calculate the new contributions to the rare decays K, and from new Z penguin and box diagrams induced by the unit-charged scalars appearing in the topcolor-assisted technicolor (TC2) models. We find that: (a) the unit-charged top-pion and b-pion can provide large contributions to the rare K decays if they are relatively light; (b) the size of the mixing elements () is strongly constrained by the data of B meson mixing: for and GeV; (c) the enhancements to the branching ratios of rare K decays from new scalars can be as large as one order of magnitude; (d) there is a strong cancellation between the short- and the long-distance dispersive part of the decay , the constraint on the new short-distance part from this decay mode is thus not strong; (e) the typical TC2 model under study is generally consistent with the available rare K-decay data. Received: 24 November 1998 / Revised version: 16 February 1999 / Published online: 15 July 1999     

Causality Implies Formal State Collapse

A physical theory of experiments carried out in a space-time region can accommodate a detector localized in another space-like separated region, in three, not necessarily exclusive, ways: (1) the detector formally collapses physical states across space-like separations, (2) the detector enables superluminal signals, and (3) the theory becomes logically inconsistent. If such a theory admits autonomous evolving states, the space-like collapse must be instantaneous. Time-like separation does not allow such conclusions. We also prove some simple results on structural stability: within the set of all possible theories, under a weak empirical topology, the set of all theories with superluminal signals and the set of all theories with retrograde signals are both open and dense.     

Penguins in ΔS = 1 nonleptonic weak decays

We discuss the use of the operator product expansion in computing nonleptonic weak decays. The estimation of “penguin” contributions is improved by a careful treatment of the u?c cancellation. Using the vacuum insertion technique and equations of motion to estimate the operator matrix element we find the penguin contribution is only $\text{1}\text{10}$ of the experimentally observed $\text{ΔI =}\text{1}\text{2}$ amplitude in kaon or hyperon decays.     

Gravitational fields near space-like and null infinity

Near space-like infinity an initial value problem for the conformal Einstein equations is formulated such that: (i) the data and equations are regular, (ii) space-like and null infinity have a finite representation, with their structure and location known a priori, and (iii) the setting relies entirely on general properties of conformal structures.A first analysis of this problem shows that the solutions develop in general a certain type of logarithmic singularity at the set where null infinity touches space-like infinity. These singularities form an intrinsic part of the solutions' conformal structure. Conditions on the free initial data near space-like infinity are derived which ensure that for solutions developing from these data singularities of this type cannot occur.     

Local and nonlocal space-like fields in the relativistic description of nucleon-nucleus scattering

It is shown that a local complex space-like nucleon-nucleus potential does not influence the observables associated with the elastic scattering, in contrast to a nonlocal space-like potential obtained from nuclear matter via a local density approximation. In order to eliminate the nonlocal space-like field, new scalar and time-like local components are defined. The energy dependence of the ratio of the strengths of the real parts of these two quantities is investigated.     

The magnitude of annihilation and penguin contributions to charm-meson decays

A consistent treatment of color singlet and octet contributions in the spectator constituent gluon model for pseudoscalar meson decays is attempted. The result comes out one order of magnitude too small to explain the observed life-time difference of D⁰ and D⁺. Furthermore, it is found that ‘penguin’ interactions in the annihilation channel may give contributions to the asymmetry of the (D⁰ → K⁺K^?)/(D⁰ → π⁺π^?) ratio of the order of the phase-space difference or larger. Finally, it is argued that annihilation cannot explain the $\text{ΔI =}\text{1}\text{2}$ rule for kaon decays; dynamical effects including the penguin interactions seem still to be needed.     

New Junction Conditions for Signature Change: Null Boundary Proposal

Existing literature on signature change considers the change surface to be space-like. We construct a new model for signature change based on the signature-changing hypersurface in the beginning of the universe being a null hypersurface. This affects most quantum cosmological considerations, since in quantum cosmology, according to the Hartle–Hawking no-boundary proposal, the creation of the Universe occurred along a space-like 3-hypersurface. Based on this assumption, junction conditions for the signature-change hypersurface are derived and the corresponding results are explained. The energy–momentum of the change surface is non-vanishing and the result for pressure of the change surface is in agreement with inflationary scenario.PACS: 98.80. HW     

Extraction of α From the CP Asymmetry in B0/B0→π+π- Decays

The influence of strong and electroweak penguin amplitudes in B/B→π⁺π^- is investigated in connection with the determination of the unitarity triangle angle a of the CKM matrix. A relation between the observable asymmetry, the angle α, and the penguin amplitude is established. A model calculation of the penguin amplitude shows that the CP asymmetry in B⁰→π⁺π^- decays is only mildly influenced by the penguin amplitudes. Experimental limits on pure penguin and penguin dominated processes are consistent with the model. This information also suggests in a rather model-independent way that penguin amplitudes will not be a serious complicating factor in the determination ofa from the π⁺π^- time-dependent asymmetry.     

Weak phase gamma using isospin analysis and time-dependent asymmetry in B(d)-->K(S)pi(+)pi(-)

We present a method for measuring the weak phase gamma using isospin analysis of three body B decays into Kpipi channels. Differential decay widths and time-dependent asymmetry in B(d)-->K(S)pi(+)pi(-) mode needs to be measured into even isospin pipi states. The method can be used to extract gamma, as well as the size of the electroweak penguin contributions. The technique is free from assumptions like SU(3) or neglect of any contributions to the decay amplitudes. By studying different regions of the Dalitz plot, it may be possible to reduce the ambiguity in the value of gamma.     

Covariant description of Hamiltonian form for field dynamics

Hamiltonian form of field dynamics is developed on a space-like hypersurface in space-time. A covariant Poisson bracket on the space-like hypersurface is defined and it plays a key role to describe every algebraic relation into a covariant form. It is shown that the Poisson bracket has the same symplectic structure that was brought in the covariant symplectic approach. An identity invariant under the canonical transformations is obtained. The identity follows a canonical equation in which the interaction Hamiltonian density generates a deformation of the space-like hypersurface. The equation just corresponds to the Yang-Feldman equation in the Heisenberg pictures in quantum field theory. By converting the covariant Poisson bracket on the space-like hypersurface to four-dimensional commutator, we can pass over to quantum field theory in the Heisenberg picture without spoiling the explicit relativistic covariance. As an example the canonical QCD is displayed in a covariant way on a space-like hypersurface.     

Space-Like Form of Bethe-Salpeter Equation: Scatter State

According to Dirac, and based on our space-like form of Bethe-Salpeter equation of bound state, we extend the definition of the space-like wavefunctions and derive out the spacelike form of Bethe-Salpeter equation for scatter state. The solution of the inhomogeneous term is also obtained in detail so as to clarify the significance of inhomogeneous space-like form of Bethe-Salpeter equation for scatter state. Moreover the translation method is finally discussed.