25,713 research outputs found
An Model for Lepton Mass Matrices with Nearly Minimal Texture
We propose a simple extension of the electroweak standard model based on the
discrete symmetry that is capable of realizing a nearly minimal
Fritzsch-type texture for the Dirac mass matrices of both charged leptons and
neutrinos. This is achieved with the aid of additional and
symmetries, one of which can be embedded in . Five complex scalar
singlet fields are introduced in addition to the SM with right-handed
neutrinos. Although more general, the modified texture of the model retains the
successful features of the minimal texture without fine-tuning; namely, it
accommodates the masses and mixing of the leptonic sector and relates the
emergence of large leptonic mixing angles with the seesaw mechanism. For large
deviations of the minimal texture, both quasidegenerate spectrum or inverted
hierarchy are allowed for neutrino masses.Comment: 11pp, 2 figures. v2: vev alignment addressed, additional analysis
performed; to appear in PR
FCNC in the minimal 3-3-1 model revisited
We show that in the minimal 3-3-1 model the flavor changing neutral currents
(FCNCs) do not impose necessarily strong constraints on the mass of the
of the model if we also consider the neutral scalar contributions to
such processes, like the neutral mesons mass difference and rare semileptonic
decays. We first obtain numerical values for all the mixing matrices of the
model i.e., the unitary matrices that rotate the left- and right-handed quarks
in each charge sector which give the correct mass of all the quarks and the CKM
mixing matrix. Then, we find that there is a range of parameters in which the
neutral scalar contributions to these processes may interfere with those of the
, implying this vector boson may be lighter than it has been thought.Comment: Extended version including the effect of a pseudoscalar. 37 pags. and
12 figures. New references added. Version matches the published versio
Looking at the photoproduction of massive gauge bosons at the LHeC
In this contribution we report on the investigation of the photoproduction of
W and Z bosons in the planned electron-proton/nucleus collider, the LHeC. The
production cross sections and the number of events are provided and theoretical
uncertainties are discussed. We also analyze the sensitivity of the LHeC
experiment to physics beyond Standard Model by studying the role played by
anomalous WWgamma coupling in the presented process.Comment: Contribution to the proceedings of the XXI International Workshop on
Deep-Inelastic Scattering and Related Subjects (DIS2013), Marseille, 22-26
April 201
Hours of work and retirement behavior
Using a novel dataset from the 2006 Portuguese Labor Force Survey this paper examines the impact of a voluntary reduction in hours of work, before retirement, on the moment of exit from the labor force. If, as often suggested, flexibility in hours of work is a useful measure to postpone retirement, then a reduction in working hours should be associated with retirement at later ages. Results prove otherwise suggesting that reducing hours of work before retirement is associated with early exits from the labor force. A reduction in hours of work seems to signal the worker’s wish to retire sooner rather than to announce the desire of remaining in the labor market.aging, retirement, working hours, older workers.
Quarkonium plus prompt-photon associated hadroproduction and nuclear shadowing
The quarkonium hadroproduction in association with a photon at high energies
provides a probe of the dynamics of the strong interactions as it is dependent
on the nuclear gluon distribution. Therefore, it could be used to constrain the
behavior of the nuclear gluon distribution in proton-nucleus and
nucleus-nucleus collisions. Such processes are useful to single out the
magnitude of the shadowing/antishadowing effects in the nuclear parton
densities. In this work we investigate the influence of nuclear effects in the
production of JPsi + photon and Upsilon + photon and estimate the transverse
momentum dependence of the nuclear modification factors. The theoretical
framework considered in the JPsi (Upsilon) production associated with a direct
photon at the hadron collider is the non-relativistic QCD (NRQCD) factorization
formalism.Comment: 8 pages, 4 figures. Final version to be published in European
Physical Journal
Hours of Work and Retirement Behavior
Using a novel dataset from the 2006 Portuguese Labor Force Survey this paper examines the impact of a voluntary reduction in hours of work, before retirement, on the moment of exit from the labor force. If, as often suggested, flexibility in hours of work is a useful measure to postpone retirement, then a reduction in working hours should be associated with retirement at later ages. Results prove otherwise suggesting that reducing hours of work before retirement is associated with early exits from the labor force. A reduction in hours of work seems to signal the worker's wish to retire sooner rather than to announce the desire of remaining in the labor market. This result may enclose the need for some alternative policy strategies regarding working hours.aging, retirement, working hours, older workers
Age and opportunities for promotion
Using a panel of new firms and their employees, this paper studies the promotion opportunities for older workers within the same firm. Survival analysis suggests that younger employees experience shorter times to promotion than older workers and, therefore, the latter face a smaller likelihood of promotion. Although men are promoted more often than women, empirical results show that women have shorter survival times to promotion than men. Also, previous promotions are stronger determinants of subsequent ones and this finding provides support to the evidence on promotion “fast-tracks”.aging, older workers, employment relationships, promotion
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