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1.
D G Hitlin 《Pramana》2006,67(5):743-753
Heavy-flavor physics, in particular B and τ physics results from the B factories, currently provides strong constraints on models of physics beyond the Standard Model. A new generation of colliders, Super B Factories, with 50 to 100 times the luminosity of existing colliders, can, in a dialog with LHC and ILC, provide unique clarification of new physics phenomena seen at those machines.  相似文献   

2.
Rahul Sinha 《Pramana》2000,55(1-2):219-228
We review the effects of new physics on CP asymmetries and decays of B mesons. Possible sources and corresponding signals for new physics are studied briefly. We discuss how the decay mode bs ℓℓ (and BK*ℓℓ) will enable us to understand the nature of new physics. We also examine the possibility of truly clean signature of new physics — a signature based on observables alone and without hadronic uncertainties.  相似文献   

3.
B. Mawlong 《Pramana》2007,69(4):521-531
The charmless nonleptonic decay modes Bf 0 K(π) involving a scalar and a pseudoscalar meson in the final state are studied. The scalar meson f 0 is considered as a q̄q state, as favored by some recent studies. Using the generalized factorization approach, the branching ratios and CP violation parameters are computed for these modes. The form factors are calculated using the results from relativistic light front quark model and the ISGW2 model. It is found that the direct CP violation parameters in these modes are small. However, the obtained branching ratios are not in agreement with the experimental data. Therefore, these modes may be considered as possible probes for new physics.   相似文献   

4.
Amarjit Soni 《Pramana》2004,62(2):415-437
Status of lattice calculations of hadron matrix elements along with CP violation inB and inK systems is reviewed. Lattice has provided useful input which, in conjunction with experimental data, leads to the conclusion that CP-odd phase in the CKM matrix plays the dominant role in the observed asymmetry inB → ψK s. It is now quite likely that any beyond the SM, CP-odd, phase will cause only small deviations in B-physics. Search for the effects of the new phase(s) will consequently require very large data samples as well as very precise theoretical predictions. Clean determination ofall the angles of the unitarity triangle therefore becomes essential. In this regardB → KD0 processes play a unique role. RegardingK-decays, remarkable progress made by theory with regard to maintenance of chiral symmetry on the lattice is briefly discussed. First application already provide quantitative information onB K and the ΔI = 1/2 rule. In the lattice calculation, the enhancement in Re A0 appears to arise solely from tree operators, esp. Q2; penguin contribution toRe A0 appears to be very small. However, improved calculations are necessary for ε’/ε as the contributions of QCD penguins and electroweak penguins largely seem to cancel. There are good reasons, though, to believe that these cancellations will not survive improvements that are now underway. Importance of determining the unitarity triangle purely fromK-decays is also emphasized.  相似文献   

5.
John M. Losecco 《Pramana》2004,62(3):583-586
We summarize results on a number of observations of penguin dominated radiative decays of theB meson. Such decays are forbidden at tree level and proceed via electroweak loops. As such they may be sensitive to physics beyond the standard model. The observations have been made at the BaBar experiment at PEP-II, the asymmetricB factory at SLAC.  相似文献   

6.
The mechanical, thermodynamical and elastic properties of Hg0.91Mn0.09Te compound are calculated by formulating an effective interionic interaction potential. This potential consists of the long-range Coulomb, three body force parameter, the Hafemeister and Flygare type short-range overlap repulsion extended upto the second neighbor ions and the van der Waals (vdW) interaction. The estimated values of phase transition pressure have revealed reasonably good agreement with the available experimental data on the phase transition pressure P t = 11.5 GPa and the vast volume discontinuity in pressure-volume (PV) phase diagram indicate the structural phase transition from zincblende (B3) to rock salt (B1) structure. Later on, the Poisson’s ratio ν, the ratio R S/B of S (Voigt averaged shear modulus) over B (bulk modulus), elastic anisotropy parameter, elastic wave velocity, average wave velocity and Debye temperature as functions of pressure is calculated. From Poisson’s ratio and the ratio R S/B it is inferred that Hg0.91Mn0.09Te is brittle in nature in both B3 phase and B1 phase. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of ductile (brittle) nature of Hg0.91Mn0.09Te compounds and still awaits experimental confirmations.  相似文献   

7.
Two series of mixed copper ferrites, Cu1+x Gex Fe2−2x O4 and Cu1+x Six Fe2−2x O4, have been analogously investigated for x=0.0, 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3. The two systems were prepared using the standard ceramic techniques. X-ray diffraction analysis indicates that both systems formed in a single phase cubic spinel structure. The lattice parameter has a constant value (0.838 nm±0.001) for the two series. The grain diameter was estimated from the scanning electron microscope micrographs for the two series. Some magnetic properties were measured at room temperature. The magnetization M was measured in the range of magnetizing field up to 5500 Am−1. The relative permeability (μr) was calculated from the B–H relation. The BH loops were measured at constant magnetizing current (I=2.5 A which is equivalent to 900 Am−1). Also, the hystersis area and the magnetic parameters Br, Bs, mR (Br/Bs) and apparent energy loss (E) were estimated from the BH loops; μr, Br, Bs and E are composition dependent.  相似文献   

8.
A monocrystal ofFe 3 O 4 is characterized by resistance, magnetoresistance and magnetic measurements in a temperature range from 4.2 K to 350 K and magnetic field-cycling from −9 T to 9 T. The resistance measurements revealed a metal-insulator Verwey transition (VT) atT v =123.76 K with activation energy E=92.5 meV at T >T v and temperature-substitute for the activation energy below the VT,T 0=E/k B ≈3800 K within 70 K–110K. The magnetotransport results independently verified the VT at 123.70 K, with discontinuous change in the magnetic moment ΔM≈0.21 ΔM≈0.21μ B and resistance hysteresis, dependent on the magnetic field in a narrow temperature range of 0.4° around theT v . The magnetic characterization established self consistentlyT v as ≈123.67 K, the jump in the magnetization at the VT≈0.25μ B and confirmed, that the magnetocrystalline anisotropy is the main microscopic mechanism responsible for the magnetization of the monocrystal (88%) with additional natural and imposed defects contributing as 12%.  相似文献   

9.
The Jones–Dole B coefficients of the electrolyte Lithium bromide (LiBr), reference salts tetra butyl ammonium tetra phenyl borate (BU4NBPh4), tetra butyl ammonium bromide (BU4NBr), and potassium chloride (KCl) in dimethylsulfoxide (DMSO), water, and DMSO–water mixtures were obtained at different temperatures range from 25 to 45 °C For this, the relative viscosities were measured for Lithium bromide (LiBr) and reference salts in DMSO, water, and DMSO–water mixtures at above-mentioned temperatures. The B coefficients of these electrolytes were behaved as structure makers in DMSO, while in H2O and DMSO–H2O mixtures, the B-coefficient values were less positive showing the weak structure-making effect. Ionic viscosity B coefficients allow us to assess the behavior of ions in the solvent mixtures. In this study it was observed that all the values of ionic B coefficient of (Li+) were positive and small showing the weak structure-making effects. It was also observed that Br ions maintain negative B coefficient values in all DMSO–H2O mixtures, except in 60% DMSO mole fraction. From this it can be concluded that Br ion behaved as a structure breaker in water and in all DMSO–H2O mixtures except in 60% DMSO mole fraction mixtures. The low B ± values of alkali metal ions and Br ions in water are due to the breakdown of the tetrahedral structural of water and the formation of strongly structured solvated ion. It is also observed that the values of the energy of activation of the flow for LiBr are greater in DMSO–water mixtures and in pure water than in DMSO. This may be due the presence of a network of hydrogen bonds which cause the hindrance in the flow of the solution of LiBr in DMSO–water mixtures and in pure water than in DMSO.  相似文献   

10.
Anirban Kundu 《Pramana》2000,55(1-2):265-270
In this talk, we point out some of the present and future possible signatures of physics beyond the Standard Model from B-meson decays, taking R-parity conserving and violating supersymmetry as illustrative examples. An expanded version is available on hep-ph archive.  相似文献   

11.
Yong-Yeon Keum 《Pramana》2004,63(6):1151-1170
We discuss applications of the perturbative QCD approach in the exclusive non-leptonic two-bodyB-meson decays. We briefly review its ingredients and some important theoretical issues on the factorization approach. PQCD results are compatible with present experimental data for charmless B-meson decays. We predict the possibility of large direct CP asymmetry in B0 → π+π (23 +7%) and B0K +π (− 17 ± 5%). We also investigate the branching ratios, CP asymmetry and isospin symmetry breaking in radiativeB(K*/ρ)γ decays.  相似文献   

12.
Nonlinear optics confronts the U(1) theory of electrodynamics with the dilemma of the existence of nonlinear fields. The U(1) group is completely linear and Abelian and causes consideration of an SU(2) theory of electrodynamics. An SU(2) theory of electrodynamics, with a B 3 magnetic field, means that physics is forced to consider an SU(2) × SU(2) electroweak theory. It is then demonstrated that the B 3 field exists on the physical vacuum defined by the Higgs symmetry breaking of this extended electroweak theory.  相似文献   

13.
14.
The LHCb experiment is in preparation, to be ready for the start of the LHC. The physics which will be performed by LHCb is reviewed, focussing on what can be learnt fromB s 0 mesons.  相似文献   

15.
Pressure-induced structural aspects and elastic properties of NaCl-type (B1) to CsCl-type (B2) structure in praseodymium chalcogenides and pnictides are presented. Ground-state properties are numerically computed by considering long-range Coulomb interactions, Hafemeister and Flygare type short-range overlap repulsion, and van der Waals interaction in the interionic potential. From the elastic constants, Poisson's ratio ν, the ratio RG/B of G (shear modulus) over B (bulk modulus), anisotropy parameter, shear and Young's moduli, Lamé's constant, Kleinman parameter, elastic wave velocity and thermodynamical property such as Debye temperature are calculated. Poisson's ratio ν and the ratio RG/B indicate that PrX and PrY are brittle in B1 phase and ductile in B2 phase. To our knowledge, this is the first quantitative theoretical prediction of the ductile (brittle) nature of praseodymium chalcogenides and pnictides and still awaits experimental confirmation.  相似文献   

16.
A new high-pressure tetragonal phase (B10) of ZnO is investigated with an ab initio calculation based on density functional theory and is compared with the cubic B1 (rocksalt structure) and B2 (CsCl structure) phases at high pressure. It is found that the B10 phase has a more covalent nature than the B2 phase. The B1, B2, and B10 phases are semiconductors and their band gap energies are determined to be 3.73, 3.15, and 3.27 eV, respectively. The B10 phase has a similar optical response to the B2 phase, but not the B1 phase. The similarity of dielectric function between B10 and B2 phases are the result of the similar profiles of electronic density of state.  相似文献   

17.
Using ab initio techniques we have calculated the electron energy loss near edge structure (ELNES) of a new high pressure phase of boron (γ‐B28) and the structurally similar allotrope, α‐B12. The total ELNES spectra are presented as weighted sums of the site specific spectra of the constituent non‐equivalent B atoms. The five different non‐equivalent B sites in γ‐B28 all show rich ELNES spectra and their similarities and differences to the simpler α‐B12 case are detailed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

18.
No Heading The Evans wave equation is derived from the appropriate Lagrangian and action, identifying the origin of the Planck constant in general relativity. The classical Fermat principle of least time, and the classical Hamilton principle of least action, are expressed in terms of a tetrad multiplied by a phase factor exp(iS/), where S is the action in general relativity. Wave (or quantum) mechanics emerges from these classical principles of general relativity for all matter and radiation fields, giving a unified theory of quantum mechanics based on differential geometry and general relativity. The phase factor exp(iS/) is an eigenfunction of the Evans wave equation and is the origin in general relativity and geometry of topological phase effects in physics, including the Aharonov-Bohm class of effects, the Berry phase, the Sagnac effect, related interferometric effects, and all physical optical effects through the Evans spin field B(3) and the Stokes theorem in differential geometry. The Planck constant is thus identified as the least amount possible of action or angular momentum or spin in the universe. This is also the origin of the fundamental Evans spin field B(3), which is always observed in any physical optical effect. It originates in torsion, spin and the second (or spin) Casimir invariant of the Einstein group. Mass originates in the first Casimir invariant of the Einstein group. These two invariants define any particle.  相似文献   

19.
The pion momentum distributions (MDs) in four channels of virtual decay p→B+π, B = N, Δ, N 1/2-(1535), N 1/2+(1440) are calculated in two models, the microscopic model of 3 P 0 scalar q−q fluctuation with the pion as a composite q−q-system and the chiral semi-microscopic model of πq interaction with the pion as a structureless Goldstone boson. The results of the above models are similar for the baryon states B = N, Δ, N 1/2-(1535) but are rather different for the Roper resonance N 1/2+(1440) which corresponds to excitation of two oscillator quanta in the nucleon. The experimental investigation of pion MDs by means of the reaction of quasi-elastic knockout of pion by an electron of a few GeV energy p(e, e′ π)B may be very suitable for Jefferson Laboratory, Virginia (JLab).  相似文献   

20.
This is the report of flavor physics and model building working group at WHEPP-9. While activites in flavor physics have been mainly focused on B-physics, those in model building have been primarily devoted to neutrino physics. We present summary of working group discussions carried out during the workshop in the above fields, and also briefly review the progress made in some projects subsequently.  相似文献   

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