3,062 research outputs found
A Real CKM Matrix and Physics Beyond the Standard Model
We study the possible existence of a real Cabibbo-Kobayashi-Maskawa (CKM)
matrix, with CP violation originating from physics beyond the standard model
(SM). We show that present experimental data allow for a real CKM matrix
provided that new physics also contributes to Delta m_{B_d} by at least 20% of
the SM contribution (for rho > 0), besides generating CP violation in the kaon
sector. The naturalness of a real CKM matrix is studied within the framework of
general multi-Higgs-doublet models with spontaneous CP violation. As an
example, we discuss a specific two-Higgs-doublet model and its implications for
CP asymmetries in non-leptonic neutral B-meson decays.Comment: 19 pages, LaTeX2e, 1 figure, uses amssymb, elsart, psfig, and subeqn
style file
Muon Detection of TeV Gamma Rays from Gamma Ray Bursts
Because of the limited size of the satellite-borne instruments, it has not
been possible to observe the flux of gamma ray bursts (GRB) beyond GeV energy.
We here show that it is possible to detect the GRB radiation of TeV energy and
above, by detecting the muon secondaries produced when the gamma rays shower in
the Earth's atmosphere. Observation is made possible by the recent
commissioning of underground detectors (AMANDA, the Lake Baikal detector and
MILAGRO) which combine a low muon threshold of a few hundred GeV or less, with
a large effective area of 10^3 m^2 or more. Observations will not only provide
new insights in the origin and characteristics of GRB, they also provide
quantitative information on the diffuse infrared background.Comment: Revtex, 12 pages, 3 postscript figures, uses epsfig.st
Top mixing in effective theories
We review how top mixing with light quarks constrains new physics beyond the
Standard Model using the effective Lagrangian approach.Comment: 4 pages, contribution to Workshop "Loops and Legs in Quantum Field
Theory", April 200
Energy barrier in the two-Higgs model
The electroweak model is extended by a second Higgs doublet and a numerical
investigation of static, finite energy classical solutions is performed. The
results indicate that for a large domain of the parameters of the Higgs
potential, the energy barrier between topologically distinct vacua of the
Lagrangian is constituted by a bisphaleron.Comment: 19 pages, including 4 eps figures, LaTex format, new results include
Only the best for my kids: An extended TPB model to understand mothersâ use of food labels
Despite the evidence that mothersâ food purchasing behavior impacts the quality of children's diet, few studies have explored psycho-social factors influencing how mothers choose the food to buy for their children. To fill this gap, this study tested an extended Theory of Planned Behavior (TPB) model to predict mothersâ tendency to seek information on food labels before purchasing food for children. Participants included 311 Italian mothers who completed a self-report questionnaire measuring their information-seeking behavior, TPB variables, anticipated regret and healthy-eater identity. Results from a Multiple Correspondence Analysis showed that mothersâ information-seeking behavior involved a continuum of choices ranging from selecting conventional or prepackaged foods to choosing to read the food label before making a purchase. Besides, a Partial Least SquaresâStructural Equation Modeling analysis showed that information-seeking behavior was positively predicted by intention (ÎČ = 0.309, p < 0.001) and healthy-eater identity (ÎČ = 0.195, p < 0.001). In turn, intention was positively affected by attitude (ÎČ = 0.208, p < 0.001), subjective norms (ÎČ = 0.155, p < 0.01), perceived behavioral control (ÎČ = 0.124, p < 0.05), anticipated regret (ÎČ = 0.193, p < 0.001), and healthy-eater identity (ÎČ = 0.191, p < 0.001). These findings emphasize that future initiatives could usefully target attitude, anticipated regret and self-identity to encourage mothersâ informed food choices for their children
Geology of the southern Gran Paradiso Massif and Lower Piedmont Zone contact area (middle Ala Valley, Western Alps, Italy)
Academic community in the face of emergency situations: Sense of responsible togetherness and sense of belonging as protective factors against academic stress during covid-19 outbreak
In the face of emergency situations, such as a global pandemic, individuals rely on their personal resources, but also on community dimensions, to deal with the unprecedented changes and risks and to safeguard their well-being. The present study specifically addresses the role of individual resources and community dimensions with reference to academic communities facing COVID-19-related lockdowns and the changes that these have implied. An online questionnaire was administered to 1124 Italian University students. It detected their sense of belonging and of responsible togetherness with reference to their academic community through community dimensions, their student self-efficacy as an individual resource, and their academic stressâpotentially stemming from studying in the middle of a pandemic. A multiple mediation model was been run with structural equation modeling. The results show that both the community dimensions associate with higher student self-efficacy and the sense of responsible togetherness, while also associating with lower academic stress. Moreover, student self-efficacy, in turn, associates with lower academic stress and mediates the relationships between both community dimensions and studentsâ academic stress levels. From these findings, the protective role that community dimensions can exert on an individualâs life becomes apparent. Building on this, further strategies should be implemented to reinforce personal and community resources in order to strengthen individuals against potentially stressful circumstances
Comment on ``Majoron emitting neutrinoless double beta decay in the electroweak chiral gauge extensions''
We point out that if the majoron-like scheme is implemented within a 331
model, there must exist at least three different mass scales for the scalar
vacuum expectation values in the model.Comment: 4 pages, no figures, Revtex. To be published in Physical Review
Effects of Flavor-dependent Annihilation on the Mixing Angle of the Isoscalar Octet-Singlet and Schwinger's Nonet Mass Formula
By incorporating the flavor-dependent quark-antiquark annihilation amplitude
into the mass-squared matrix describing the mixing of the isoscalar states of a
meson nonet, the new version of Schwinger's nonet mass formula which holds with
a high accuracy for the , , , and
nonets is derived and the mixing angle of isoscalar octet-singlet for these
nonets is obtained. In particular, the mixing angle of isoscalar octet-singlet
for pseudoscalar nonet is determined to take the value of , which
is in agreement with the value of deduced from a
rather exhaustive and up-to-date analysis of data. It is also pointed out that
the omission of the flavor-dependent annihilation effect might be a
factor resulting in the invalidity of Schwinger's original nonet mass formula
for pseudoscalar nonet.Comment: Latex, 7 page
Detailing the exhumation history of the Western Alps through the eyes of glaucophane-bearing eclogitic rocks: preliminary metamorphic data from the Internal Piedmont Zone
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