18 research outputs found
Light Quark Masses in Multi-Quark Interactions
We suggest and discuss in detail a multi-quark three flavor Lagrangian of the
Nambu -- Jona-Lasinio type, which includes a set of effective interactions
proportional to the current quark masses. It is shown that within the dynamical
chiral symmetry breaking regime, the masses of the pseudo Goldstone bosons and
their chiral partners, members of the low lying scalar nonet, are in perfect
agreement with current phenomenological expectations. The role of the new
interactions is analyzed.Comment: 8 pages, published versio
Strength of the Trilinear Higgs Boson Coupling in Technicolor Models
We discuss the strength of the trilinear Higgs boson coupling in technicolor
(or composite) models in a model independent way. The coupling is determined as
a function of a very general ansatz for the technicolor self-energy, and turns
out to be equal or smaller than the one of the standard model Higgs boson
depending on the dynamics of the theory. With this trilinear coupling we
estimate the cross section for Higgs boson pair production at the LHC. This
measurement is quite improbable in the case of a heavy standard model Higgs
boson, but it will be even worse when this boson is dynamically generated.Comment: 20 pages, 4 figures, Typos correcte
Body Fixed Frame, Rigid Gauge Rotations and Large N Random Fields in QCD
The "body fixed frame" with respect to local gauge transformations is
introduced. Rigid gauge "rotations" in QCD and their \Sch equation are studied
for static and dynamic quarks. Possible choices of the rigid gauge field
configuration corresponding to a nonvanishing static colormagnetic field in the
"body fixed" frame are discussed. A gauge invariant variational equation is
derived in this frame. For large number N of colors the rigid gauge field
configuration is regarded as random with maximally random probability
distribution under constraints on macroscopic--like quantities. For the uniform
magnetic field the joint probability distribution of the field components is
determined by maximizing the appropriate entropy under the area law constraint
for the Wilson loop. In the quark sector the gauge invariance requires the
rigid gauge field configuration to appear not only as a background but also as
inducing an instantaneous quark-quark interaction. Both are random in the large
N limit.Comment: 29 pages LATEX, Weizmann Institute preprint WIS-93/40/Apr -P
General relativity as an effective field theory: The leading quantum corrections
I describe the treatment of gravity as a quantum effective field theory. This
allows a natural separation of the (known) low energy quantum effects from the
(unknown) high energy contributions. Within this framework, gravity is a well
behaved quantum field theory at ordinary energies. In studying the class of
quantum corrections at low energy, the dominant effects at large distance can
be isolated, as these are due to the propagation of the massless particles
(including gravitons) of the theory and are manifested in the
nonlocal/nonanalytic contributions to vertex functions and propagators. These
leading quantum corrections are parameter-free and represent necessary
consequences of quantum gravity. The methodology is illustrated by a
calculation of the leading quantum corrections to the gravitational interaction
of two heavy masses.Comment: 34 pages, Latex, UMHEP-40
Low Energy Chiral Lagrangian in Curved Space-Time from the Spectral Quark Model
We analyze the recently proposed Spectral Quark Model in the light of Chiral
Perturbation Theory in curved space-time. In particular, we calculate the
chiral coefficients , as well as the coefficients ,
, and , appearing when the model is coupled to gravity. The
analysis is carried for the SU(3) case. We analyze the pattern of chiral
symmetry breaking as well as elaborate on the fulfillment of anomalies.
Matching the model results to resonance meson exchange yields the relation
between the masses of the scalar, tensor and vector mesons,
. Finally, the
large- limit suggests the dual relations in the vector and scalar
channels, and .Comment: 18 pages, no figure
Mass and width of a composite Higgs boson
The scalar Higgs boson mass in a Technicolor model was obtained by Elias and
Scadron with the analysis of an homogeneous Bethe-Salpeter equation (BSE),
however it was performed before the most recent developments of walking gauge
theories. It was not observed in their work that dynamically generated
technifermion mass may vary according to the theory dynamics that forms the
scalar bound state. This will be done in this work and we also call attention
that their calculation must change to take into account the normalization
condition of the BSE. We compute the width of the composite boson and show how
the gauge group and fermion content of a technicolor theory can be inferred
from the measurement of the mass and width of the scalar boson.Comment: New reference and new figure added. Additional discussion about
experimental constraints. Typos correcte
Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance
A precision measurement of absolute pi+p and pi-p elastic differential cross
sections at incident pion laboratory kinetic energies from T_pi= 141.15 to
267.3 MeV is described. Data were obtained detecting the scattered pion and
recoil proton in coincidence at 12 laboratory pion angles from 55 to 155
degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm
measurements were also obtained for pi+p energies up to 218.1 MeV, with the
scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled,
super-cooled liquid hydrogen target as well as solid CH2 targets were used. The
data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5%
normalization. The reliability of the cross section results was ensured by
carrying out the measurements under a variety of experimental conditions to
identify and quantify the sources of instrumental uncertainty. Our lowest and
highest energy data are consistent with overlapping results from TRIUMF and
LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave
analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA
solution KH80 does not.Comment: 39 pages, 22 figures (some with quality reduced to satisfy ArXiv
requirements. Contact M.M. Pavan for originals). Submitted to Physical Review
Radiative Decay of a Long-Lived Particle and Big-Bang Nucleosynthesis
The effects of radiatively decaying, long-lived particles on big-bang
nucleosynthesis (BBN) are discussed. If high-energy photons are emitted after
BBN, they may change the abundances of the light elements through
photodissociation processes, which may result in a significant discrepancy
between the BBN theory and observation. We calculate the abundances of the
light elements, including the effects of photodissociation induced by a
radiatively decaying particle, but neglecting the hadronic branching ratio.
Using these calculated abundances, we derive a constraint on such particles by
comparing our theoretical results with observations. Taking into account the
recent controversies regarding the observations of the light-element
abundances, we derive constraints for various combinations of the measurements.
We also discuss several models which predict such radiatively decaying
particles, and we derive constraints on such models.Comment: Published version in Phys. Rev. D. Typos in figure captions correcte
Health-related quality-of-life trajectories over time in older men and women with advanced chronic kidney disease
Background and objectives The effect of sex on longitudinal health-related quality of life remains unknown in CKD. Here we assess differences in the sex-specific evolution of health-related quality of life in older men and women with advanced CKD.Design, setting, participants, & measurements The European Quality Study on Treatment in Advanced Chronic Kidney Disease is a European observational prospective cohort study in referred patients with CKD and an incident eGFR = 65 years of age not on dialysis. Health-related quality of life was measured using the 36-Item Short Form Survey at 3- to 6-month intervals between April 2012 and September 2020, providing Physical Component Summary and Mental Component Summary scores. Trajectories were modeled by sex using linear mixed models, and sex differences in health-related quality-of-life slope were explored. Results We included 5345 health-related quality-of-life measurements in 1421 participants. At baseline, women had considerably lower mean Physical Component Summary (42) and Mental Component Summary (60) compared with men (Physical Component Summary: 55; Mental Component Summary: 69; P < 0.001). However, during follow-up, Physical Component Summary and Mental Component Summary scores declined approximately twice as fast in men (Physical Component Summary: 2.5 per year; 95% confidence interval, 1.8 to 3.1; Mental Component Summary: 2.7 per year; 95% confidence interval, 2.0 to 3.4) compared with in women (Physical Component Summary: 1.1 per year; 95% confidence interval, 0.1 to 2.0; Mental Component Summary: 1.6 per year; 95% confidence interval, 0.7 to 2.6). This difference was partly attenuated after adjusting for important covariates, notably eGFR decline. Higher serum phosphate, lower hemoglobin, and the presence of preexisting diabetes were associated with lower Physical Component Summary and Mental Component Summary scores in men but to a lesser extent in women. Conclusions Among older men and women with advanced CKD, women had lower health-related quality of life at baseline, but men experienced a more rapid decline in health-related quality of life over time.Clinical epidemiolog
de Sitter gauge theories and induced gravities
Pure de Sitter, anti de Sitter, and orthogonal gauge theories in
four-dimensional Euclidean spacetime are studied. It is shown that, if the
theory is asymptotically free and a dynamical mass is generated, then an
effective geometry may be induced and a gravity theory emerges. The asymptotic
freedom and the running of the mass might account for an In\"on\"u-Wigner
contraction which induces a breaking of the gauge group to the Lorentz group,
while the mass itself is responsible for the coset sector of the gauge field to
be identified with the effective vierbein. Furthermore, the resulting local
isometries are Lorentzian for the anti de Sitter group and Euclidean for the de
Sitter and orthogonal groups.Comment: Sections added. Text reviewed. References added. 14 pages, no
figures. Final version to appear in EPJ