Circumstantial evidence for rotating mass matrix from fermion mass and mixing data

It is shown that existing data on the mixing between up and down fermion states and on the hierarchical mass ratios between fermion generations, as far as can be so analyzed at present, are all consistent with the two phenomena being both consequences of a mass matrix rotating in generation space with changing energy scale. As a result, the rotating mass matrix can be traced over some 14 orders of magnitude in energy from the mass scale of the t quark at 175 GeV to below that of the atmospheric neutrino at 0.05 eV. Received: 27 August 2002 / Published online: 24 January 2003 RID="a" ID="a" e-mail: jose.m.bordes@uv.es RID="b" ID="b" e-mail: h.m.chan@rl.ac.uk RID="c" ID="c" e-mail: tsou@maths.ox.ac.uk     

On decoupling of massless modes in NCOS theories

We revisit the decoupling phenomenon of massless modes in non-commutative open string (NCOS) theories. We check the decoupling by explicit computation in (2+1) or higher dimensional NCOS theories and recapitulate the validity of the decoupling to all orders in perturbation theory. Received: 23 April 2002 / Published online: 25 October 2002 RID="a" ID="a" e-mail: hyun@phya.yonsei.ac.kr RID="b" ID="b" e-mail: sangmin@newton.skku.ac.kr RID="c" ID="c" e-mail: hshin@kias.re.kr     

Implications of $B \to \rho \gamma$ measurements in the standard model and supersymmetric theories

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     

Fourth generation effects in processes induced by the $b \rightarrow s$ transition

We study the effects of sequential fourth quark generation in rare decays induced by the transition and in B _s ⁰- mixing. Using the experimental values on the branching ratios of the and decays, the allowed regions for and are determined as a function of the t ^' quark mass. Received: 3 April 2003 / Published online: 2 June 2003 RID="a" ID="a" e-mail: taliev@metu.edu.tr RID="b" ID="b" e-mail: ozpineci@ictp.trieste.it RID="c" ID="c" e-mail: savci@metu.edu.tr     

LMA solution to the solar neutrino problem and a phenomenological charged lepton mass matrix

We propose a phenomenological form of the charged lepton mass matrix which extends the idea of a ”lopsided” mass matrix found in the literature. The features of the form are that both the 2-3 and 1-3 elements of the charged lepton mass matrix are of order 1 and that the small elements have a new structure. This form leads to the interesting result that both large atmospheric and solar neutrino mixing can be accounted for by the matrix. Another interesting result of this mass matrix is that it leads to very small 1-3 mixing in the lepton sector and can suppress the branching ratio of under the present experimental limit in the supersymmetric see-saw case. Received: 3 October 2002 / Revised version: 10 November 2002 / Published online: 24 January 2003 RID="a" ID="a" e-mail: bixj@mail.tsinghua.edu.cn RID="b" ID="b" e-mail: dyb@itp.ac.cn     

How well can we reconstruct the $t\bar{t}$ system near its threshold at future ee linear colliders?

We developed a new method for the full kinematical reconstruction of the system near its threshold at future linear e ⁺ e ^- colliders. In the core of the method lies likelihood fitting which is designed to improve measurement accuracies of the kinematical variables that specify the final states resulting from decays. The improvement is demonstrated by applying this method to a Monte Carlo sample generated with various experimental effects including beamstrahlung, finite acceptance and resolution of the detector system, etc. In most cases the fit takes a broad non-Gaussian distribution of a given kinematical variable to a nearly Gaussian shape, thereby justifying phenomenological analyses based on simple Gaussian smearing of the parton-level momenta. The standard deviations of the resultant distributions of various kinematical variables are given in order to facilitate such phenomenological analyses. A possible application of the kinematical fitting method and its expected impact are also discussed. Received: 4 March 2003 / Published online: 23 May 2003 RID="a" ID="a" e-mail: ikematsu@post.kek.jp RID="b" ID="b" e-mail: fujiik@jlcuxf.kek.jp RID="c" ID="c" e-mail: hioki@ias.tokushima-u.ac.jp RID="d" ID="d" e-mail: sumino@tuhep.phys.tohoku.ac.jp RID="e" ID="e" e-mail: tohrut@hiroshima-u.ac.jp     

<Emphasis Type="Italic">B</Emphasis> to light meson transition form factors calculated in perturbative QCD approach

We calculate the , (P is the light pseudoscalar meson, V the light vector meson) form factors in the large-recoil limit in the perturbative QCD approach, including both the vector (axial vector) and tensor operators. In general there are two leading components and for the B meson wave functions. We consider both contributions of them. Sudakov effects ( and threshold resummation) are included to regulate the soft end-point singularity. By choosing the hard scale as the maximum virtualities of the internal particles in the hard b quark decay amplitudes, Sudakov factors can effectively suppress the long-distance soft contribution. The hard contribution can be dominant in these approaches. Received: 27 December 2002 / Published online: 5 May 2003 RID="a" ID="a" e-mail: lucd@mail.ihep.ac.cn RID="b" ID="b" e-mail: yangmz@mail.ihep.ac.cn     

A universal Regge pole model for all vector meson exclusive photoproduction by real and virtual photons

A model based on a dipole pomeron framework for exclusive vector meson photoproduction by real and virtual photons shows very good agreement with the experimental data. This model does not violate unitarity constraints and describes in a universal manner all the available data for , , , and vector meson photoproduction in the region of energies and photon virtualities . Received: 18 December 2001 / Published online: 25 October 2002 RID="a" ID="a" e-mail: martynov@bitp.kiev.ua RID="b" ID="b" e-mail: predazzi@to.infn.it RID="c" ID="c" e-mail: prokudin@to.infn.it     

Towards high-precision predictions for the MSSM Higgs sector

The status of the evaluation of the MSSM Higgs sector is reviewed. The phenomenological impact of recently obtained corrections is discussed. In particular it is shown that the upper bound on m_h within the MSSM is shifted upwards. Consequently, lower limits on obtained by confronting the upper bound as function of with the lower bound on m_h from Higgs searches are significantly weakened. Furthermore, th e region in the M_A--plane where the coupling of the lightest Higgs boson to down-type fermions is suppressed is modified. The presently not calculated higher-order corrections to the Higgs-boson mass matrix are estimated to shift the mass of the lightest Higgs boson by up to 3 GeV. Received: 12 December 2002 / Published online: 3 March 2003 RID="a" ID="a" e-mail: giuseppe.degrassi@roma3.infn.it RID="b" ID="b" e-mail: Sven.Heinemeyer@physik.uni-muenchen.de RID="c" ID="c" e-mail: hollik@mppmu.mpg.de RID="d" ID="d" e-mail: slavich@mppmu.mpg.de RID="e" ID="e" e-mail: Georg.Weiglein@durham.ac.uk     

Compressible bag model and the phase structure

The phase structure of hadrons and the quark-gluon plasma is investigated by two types of equation of state of the hadrons, namely the ideal hadron gas model and the compressible bag model. It is pointed out that, while the ideal gas model produces an unrealistic extra hadron phase, the compressible bag model gives the expected and reasonable phase diagram even if the rich hadron spectrum is taken into account. Received: 22 February 2002 / Revised version: 28 June 2002 / Published online: 20 September 2002 RID="a" ID="a" e-mail: kagiyama@sci.kagoshima-u.ac.jp RID="b" ID="b" e-mail: kumamoto@cosmos01.cla.kagoshima-u.ac.jp RID="c" ID="c" e-mail: minaka@edu.kagoshima-u.ac.jp RID="d" ID="d" e-mail: nakamura@sci.kagoshima-u.ac.jp RID="e" ID="e" e-mail: ohkura@cosmos01.cla.kagoshima-u.ac.jp RID="f" ID="f" e-mail: yamaguchi@cosmos01.cla.kagoshima-u.ac.jp     

Non-leptonic <Emphasis Type="Italic">B</Emphasis> decays into a charmed tensor meson

In the framework of factorization and the heavy quark effective theory, modes are analyzed. We adopt the result from the QCD sum rule calculation for the hadronic matrix elements at leading order of and . The QCD sum rule results are well compatible with the current data, with the prediction for the branching ratios and for . We give constraints on the interception and the slope parameter of the leading Isgur-Wise function from the experimental bounds. It is argued that the observation of non-zero directly measures the non-factorizable effects. Received: 18 July 2002 / Revised version: 21 October 2002 / Published online: 14 March 2003 RID="a" ID="a" e-mail: jplee@phya.yonsei.ac.kr     

Time-ordered perturbation theory on non-commutative spacetime II: Unitarity

We examine the unitarity issue in the recently proposed time-ordered perturbation theory on noncommutative (NC) spacetime. We show that unitarity is preserved as long as the interaction Lagrangian is explicitly hermitian. We explain why it makes sense to distinguish the hermiticity of the Lagrangian from that of the action in perturbative NC field theory and how this requirement fits in this framework. Received: 25 June 2002 / Published online: 30 August 2002 RID="a" ID="a" e-mail: liaoy@itp.uni-leipzig.de RID="b" ID="b" e-mail: sibold@itp.uni-leipzig.de     

QCD saturation and $\gamma^{*}$-$\gamma^{*}$ scattering

Two photon collisions at high energy have an important theoretical advantage: the simplicity of the initial state, which gives us a unique opportunity to calculate these processes for large virtualities of both photons in the perturbative QCD approach. In this paper we study QCD saturation in two photon collisions in the framework of the Glauber-Mueller approach. The Glauber-Mueller formula is derived emphasising the impact parameter dependence (b_t) of the dipole-dipole amplitude. It is shown that non-perturbative QCD contributions are needed to describe the large b _t behaviour, and the way how to deal with them is suggested. Our approach can be viewed as the model for the saturation in which the entire impact parameter dependence is determined by the initial conditions. The unitarity bound for the total cross section, its energy dependence as well as predictions for future experiments are discussed. It is argued that the total cross section increases faster than any power of in a wide range of energy or x, namely -, where reflects the x dependence of the gluon density and is the pion mass. Received: 22 November 2002 / Revised version: 27 January 2003 / Published online: 5 May 2003 RID="a" ID="a" e-mail: kozlov@post.tau.ac.il RID="b" ID="b" e-mail: leving@post.tau.ac.il and levin@mail.desy.de     

The spontaneous generation of magnetic fields at high temperature in a supersymmetric theory

The spontaneous generation of magnetic and chromomagnetic fields at high temperature in the minimal supersymmetric standard model is investigated. The consistent effective potential including the one-loop and the daisy diagrams of all bosons and fermions is calculated and the magnetization of the vacuum is observed. The mixing of the generated fields due to the quark and s-quark loop diagrams and the role of superpartners are studied in detail. It is found that the contribution of these diagrams increases the magnetic and chromomagnetic field strengths as compared with the case of a separate generation of fields. The magnetized vacuum state is found to be stable due to the magnetic masses of gauge fields included in the daisy diagrams. Applications of the results obtained are discussed. A comparison with the standard model case is given. Received: 18 October 2002 / Revised version: 23 December 2002 / Published online: 3 March 2003 RID="a" ID="a" e-mail: vadimdi@yahoo.com RID="b" ID="b" e-mail: skalozub@ff.dsu.dp.ua     

Probing the Majorana mass scale of right-handed neutrinos in mSUGRA

We discuss the perspectives of testing the right-handed Majorana mass scale M_R of the SUSY see-saw model in the mSUGRA framework. Lepton-flavor violating low energy processes are analyzed in recently proposed post-LEP benchmark scenarios, taking into account present uncertainties and future developments in the neutrino sector. Non-observation of in the next-generation PSI experiment will provide upper bounds on M_R of the order of GeV, while on the other hand, a positive signal for at SUPERKEKB or the LHC may determine M_R for a given mSUGRA scenario with an accuracy of a factor of 2. Received: 14 June 2002 / Revised version: 7 January 2003 / Published online: 14 April 2003 RID="a" ID="a" e-mail: deppisch@physik.uni-wuerzburg.de RID="b" ID="b" e-mail: paes@physik.uni-wuerzburg.de RID="c" ID="c" e-mail: asredelb@physik.uni-wuerzburg.de RID="d" ID="d" e-mail: rueckl@physik.uni-wuerzburg.de RID="e" ID="e" e-mail: shimizu@eken.phys.nagoya-u.ac.jp     

Deconstructing scalar QED at zero and finite temperature

We calculate the effective potential for the WLPNGB in a world with a circular latticized extra dimension. The mass of the Wilson line pseudo-Nambu-Goldstone boson (WLPNGB) is calculated from the one-loop quantum effect of scalar fields at zero and finite temperature. We show that a series expansion by the modified Bessel functions is useful to calculate the one-loop effective potentials. Received: 24 January 2003 / Published online: 14 April 2003 RID="a" ID="a" e-mail: b1834@sty.cc.yamaguchi-u.ac.jp RID="b" ID="b" e-mail: b1795@sty.cc.yamaguchi-u.ac.jp RID="c" ID="c" e-mail: shiraish@po.cc.yamaguchi-u.ac.jp     

Role of electric field polarisation in rotational transitions

The molecular dynamics of polar diatomic molecule, interacting with linearly and circularly polarised laser field is studied. Non-perturbative quasi-energy technique is used to determine the rotational field surfaces. Degeneracy in different M-levels is found to be removed in the presence of circularly polarised electromagnetic radiation. In this paper, we present the calculations exhibiting the dynamics of rotational excitation of a linear molecule and characteristic features of spectra which become observable in considered fields. Received 22 March 2002 / Received in final form 15 July 2002 Published online 6 November 2002 RID="a" ID="a"e-mail: nsinghal@physics.du.ac.in RID="b" ID="b"e-mail: vnautiyal@himalaya.du.ac.in RID="c" ID="c"e-mail: manmohan@physics.du.ac.in