916 research outputs found
Fine-Tuning Constraints on Supergravity Models
We discuss fine-tuning constraints on supergravity models. The tightest
constraints come from the experimental mass limits on two key particles: the
lightest CP even Higgs boson and the gluino. We also include the lightest
chargino which is relevant when universal gaugino masses are assumed. For each
of these particles we show how fine-tuning increases with the experimental mass
limit, for four types of supergravity model: minimal supergravity, no-scale
supergravity (relaxing the universal gaugino mass assumption), D-brane models
and anomaly mediated supersymmetry breaking models. Among these models, the
D-brane model is less fine tuned.The experimental propects for an early
discovery of Higgs and supersymmetry at LEP and the Tevatron are discussed in
this framework.Comment: 17 pages, Latex, including 5 eps figure
Associations between Family Maltreatment Perpetration and Latent Profiles of Personal and Family Strengths among Active-Duty Air Force Members
Although individual and family strengths have been found to impact family maltreatment risk, optimal approaches to their assessment are lacking. To substantiate the utility of holistically assessing multiple strengths among active-duty Air Force members (i.e., Airmen) who might be at risk of perpetrating family maltreatment, the current study aimed to identify latent patterns of personal and family strengths among Airmen and assess associations with family maltreatment perpetration. A representative a sample of 30,187 Airmen from the 2011 Air Force Community Assessment Survey was used to identify patterns across latent-factor scores representing unit leader support, informal support, family functioning, individual fitness, and personal resilience. Latent profile analysis was conducted to extract an optimal number of response patterns and estimate associations with family maltreatment perpetration. A five-profile solution was optimal, representing patterns marked by low (10%), below average (26%), mixed (16%), above average (36%), and high (12%) levels of personal and family strengths. Predicted probabilities of family maltreatment among families not identifying as stepfamilies were 39%, 21%, 14%, 10%, and 8% across low, below average, mixed, above average, and high patterns, respectively. Among stepfamilies (20% of sample), predicted probabilities were 49%, 29%, 21%, 15%, and 12%, respectively. Findings encourage a holistic assessment of personal and family strengths among Airmen. The Personal and Family Strengths Inventory, which was developed to gauge these strengths, can position practitioners well to engage Airmen in conversations around strengths and growth opportunities for the purposes of service planning aimed at preventing family maltreatment
Quark and Lepton Mass Patterns and the Absolute Neutrino Mass Scale
We investigate what could be learned about the absolute scale of neutrino
masses from comparisons among the patterns within quark and lepton mass
hierarchies. First, we observe that the existing information on neutrino masses
fits quite well to the unexplained, but apparently present regularities in the
quark and charged lepton sectors. Second, we discuss several possible mass
patterns, pointing out that this quite generally leads towards hierarchical
neutrino mass patterns especially disfavoring the vacuum solution.Comment: final version to be published in PRD, 5 pages, 2 figures, RevTe
Naturalness Implications of LEP Results
We analyse the fine-tuning constraints arising from absence of superpartners
at LEP, without strong universality assumptions. We show that such constraints
do not imply that charginos or neutralinos should have been seen at LEP,
contrary to the usual arguments. They do however imply relatively light gluinos
(m_{\tilde g} \lsim 350 GeV) and/or a relation between the soft-breaking
SU(3) gaugino mass and Higgs soft mass . The LEP limit on the Higgs
mass is significant, especially at low , and we investigate to what
extent this provides evidence for both a lighter gluino and correlations
between soft masses.Comment: 22 pages, Latex, including 2 eps figure
5D seesaw, flavor structure, and mass textures
In the 5D theory in which only 3 generation right-handed neutrinos are in the
bulk, the neutrino flavor mixings and the mass spectrum can be constructed
through the seesaw mechanism. The 5D seesaw is easily calculated just by a
replacement of the
Majorana mass eigenvalues, M_i, by 2 M_*tan(h)[\pi RM_i] (M_*: 5D Planck
scale,
R: compactification radius). The 5D features appear when the bulk mass, which
induces the 4D Majorana mass, is the same as the compactification scale or
larger than it. Depending on the type of bulk mass, the seesaw scales of the 3
generations are strongly split (the tan-function case) or degenerate (the
tanh-function case). In the split case, the seesaw enhancement is naturally
realized. The single right-handed neutrino dominance works in a simple setup,
and some specific mass textures, which are just assumptions in the 4D setup,
can be naturally obtained in
5 dimensions. The degenerate case is also useful for a suitable neutrino
flavor structure.Comment: 15 page
Energy Independent Solution to the Solar Neutrino Anomaly including the SNO data
The global data on solar neutrino rates and spectrum, including the SNO
charged current rate, can be explained by LMA, LOW or the energy independent
solution -- corresponding to near-maximal mixing. All the three favour a mild
upward renormalisation of the Cl rate. A mild downward shift of the
neutrino flux is favoured by the energy independent and to a lesser extent the
LOW solution, but not by LMA. Comparison with the ratio of SK elastic and SNO
charged current scattering rates favours the LMA over the other two solutions,
but by no more than .Comment: 18 pages, latex, 3 figure
CP and Lepton-Number Violation in GUT Neutrino Models with Abelian Flavour Symmetries
We study the possible magnitudes of CP and lepton-number-violating quantities
in specific GUT models of massive neutrinos with different Abelian flavour
groups, taking into account experimental constraints and requiring successful
leptogenesis. We discuss SU(5) and flipped SU(5) models that are consistent
with the present data on neutrino mixing and upper limits on the violations of
charged-lepton flavours and explore their predictions for the CP-violating
oscillation and Majorana phases. In particular, we discuss string-derived
flipped SU(5) models with selection rules that modify the GUT structure and
provide additional constraints on the operators, which are able to account for
the magnitudes of some of the coefficients that are often set as arbitrary
parameters in generic Abelian models.Comment: 30 pages, 6 figure
Deviation of Atmospheric Mixing from Maximal and Structure in the Leptonic Flavor Sector
I attempt to quantify how far from maximal one should expect the atmospheric
mixing angle to be given a neutrino mass-matrix that leads, at zeroth order, to
a nu_3 mass-eigenstate that is 0% nu_e, 50% nu_mu, and 50% nu_tau. This is done
by assuming that the solar mass-squared difference is induced by an
"anarchical" first order perturbation, an approach than can naturally lead to
experimentally allowed values for all oscillation parameters. In particular,
both |cos 2theta_atm| (the measure for the deviation of atmospheric mixing from
maximal) and |U_e3| are of order sqrt(Delta m^2_sol/Delta m^2_atm) in the case
of a normal neutrino mass-hierarchy, or of order Delta m^2_sol/Delta m^2_atm in
the case of an inverted one. Hence, if any of the textures analyzed here has
anything to do with reality, next-generation neutrino experiments can see a
nonzero cos 2theta_atm in the case of a normal mass-hierarchy, while in the
case of an inverted mass-hierarchy only neutrino factories should be able to
see a deviation of sin^2 2theta_atm from 1.Comment: 12 pages, no figures, references and acknowledgments adde
A Model of Fermion Masses and Flavor Mixings with Family Symmetry
The family symmetry is proposed to solve flavor problems
about fermion masses and flavor mixings. It's breaking is implemented by some
flavon fields at the high-energy scale. In addition a discrete group is
introduced to generate tiny neutrino masses, which is broken by a real singlet
scalar field at the middle-energy scale. The low-energy effective theory is
elegantly obtained after all of super-heavy fermions are integrated out and
decoupling. All the fermion mass matrices are regularly characterized by four
fundamental matrices and thirteen parameters. The model can perfectly fit and
account for all the current experimental data about the fermion masses and
flavor mixings, in particular, it finely predicts the first generation quark
masses and the values of and in neutrino
physics. All of the results are promising to be tested in the future
experiments.Comment: 14 pages, 1 figure, to make a few of corrections to the old version.
arXiv admin note: substantial text overlap with arXiv:1011.457
Leading Order Textures for Lepton Mass Matrices
In theories with three light neutrinos, certain simplicity assumptions allow
the construction of a complete list of leading order lepton mass matrices.
These matrices are consistent with m_{tau} \neq 0, Delta m^2_{12} \ll Delta
m^2_{23}, theta_{23} approx 1, and theta_{13} = 0, as suggested by measurements
of atmospheric and solar neutrino fluxes. The list contains twelve generic
cases: two have three degenerate neutrinos, eight have two neutrinos forming a
Dirac state, and in only two cases is one neutrino much heavier than the other
two. For each of these twelve generic cases the possible forms for the
perturbations which yield m_{mu} are given. Ten special textures are also
found.Comment: 17 pages, added reference
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