848 research outputs found
Graviton loops and brane observables
We discuss how to consistently perform effective Lagrangian computations in
quantum gravity with branes in compact extra dimensions. A reparametrization
invariant and infrared finite result is obtained in a non trivial way. It is
crucial to properly account for brane fluctuations and to correctly identify
physical observables. Our results correct some confusing claims in the
literature. We discuss the implications of graviton loops on electroweak
precision observables and on the muon g-2 in models with large extra
dimensions. We model the leading effects, not controlled by effective field
theory, by introducing a hard momentum cut-off.Comment: 9 pages + 4 eps figures, JHEP style latex document. The paper is
composed by a theoretical part, followed (after page 21) by a
phenomenological part. v2: version published in JHEP, few typos corrected.
v3: few additional typos corrected in the Appendi
Electroweak Symmetry Breaking Beyond the SM
Proceedings URL: http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=10
Heavy-heavy form factors and generalized factorization
We reanalyze B -> D pi and B -> K J/psi data to extract a set of parameters
which give the relevant hadronic matrix elements in terms of factorized
amplitudes. Various sources of theoretical uncertainties are studied, in
particular those depending on the model adopted for the form factors. We find
that the fit to the B -> D pi branching ratios substantially depends on the
model describing the Isgur-Wise function and on the value of its slope. This
dependence can be reduced by substituting the BR(B -> D pi) with suitable
ratios of non-leptonic to differential semileptonic BRs. In this way, we obtain
a model-independent determination of these parameters. Using these results, the
B -> D form factors at q^2=M_pi^2 can be extracted from a fit of the BR(B -> D
pi). The comparison between the form factors obtained in this way and the
corresponding measurements in semileptonic decays can be used as a test of
(generalized) factorization free from the uncertainties due to heavy-heavy form
factor modeling. Finally, we present predictions for yet-unmeasured D pi and D
K branching ratios and extract f_{D_s} and f_{D_s^*} from B -> DD_s decays. We
find f_{D_s} = 270 +- 45 MeV and f_{D_s^*}=260 +- 40 MeV, in good agreement
with recent measurements and lattice calculations.Comment: 20 pages, 16 ps/eps files, uses epsfig.sty; exp. numbers update
Partly Supersymmetric Grand Unification
It is shown how grand unification can occur in models which are partly
supersymmetric. The particle states which are composite do not contribute to
the running of gauge couplings above the compositeness scale, while the
elementary states contribute the usual large logarithmns. This introduces a new
differential running contribution to the gauge couplings from partly composite
SU(5) matter multiplets. In particular, for partly supersymmetric models, the
incomplete SU(5) elementary matter multiplets restore gauge coupling
unification even though the usual elementary gaugino and Higgsino contributions
need not be present.Comment: 14 pages, LaTe
Liability for Deadly Failure: Rejecting the Push for PREP Act Preemption and Restraining PREP Act Immunity for Senior Living Facilities and Nursing Homes
In the wake of COVID-19, there has been a surge of wrongful death cases filed by plaintiff families in state courts. These families allege that their loved one contracted and died from COVID-19 because the nursing home or senior living facility at which their loved one resided failed to take proper COVID-19 prevention measures. In response, defendant facilities have removed these actions to federal court, arguing that the PREP Act preempts plaintiffs’ state law claims and grants facilities immunity from liability for loss related to qualified actions taken during a public health emergency. This Comment rejects facilities’ push for preemption which has been used as a tactic to stretch out litigation and to encourage plaintiff families to settle their cases for less. This Comment also encourages amendment of the PREP Act immunity laws to clarify that the Act does not preempt state law claims but does restrict senior living facilities and nursing homes from the privilege of immunity for loss resulting from a failure to act. Restraining immunity in this way will hold facilities accountable for their deadly failure to take COVID- 19 safety precautions and will incentivize facilities to take more stringent precautions when caring for their elderly residents in the future
Factorization, charming penguins, and all that
We discuss few selected topics related to the calculation of hadronic
amplitudes relevant for two-body non-leptonic B decays.Comment: LaTeX, 9 pages, 1 eps figure included, uses psfig.sty. Talk given by
M.C. at Beauty '97, UCLA, USA, October 13-17, 199
Epsilon' from supersymmetry with non universal A terms?
In supersymmetric theories with a motivated flavour structure, we investigate
the possibility that an epsilon' parameter as large as the measured value be
generated without conflicting with the bounds from electron and neutron
electric dipoles and mu --> e gamma.Comment: 8 pages. v2: we have cancelled hep-ph/9510303 as a motivation for non
universal A terms, because it is wrong. v3,4: A significant sign error
corrected. Conclusions unchange
Partially Supersymmetric Composite Higgs Models
We study the idea of the Higgs as a pseudo-Goldstone boson within the
framework of partial supersymmetry in Randall-Sundrum scenarios and their CFT
duals. The Higgs and third generation of the MSSM are composites arising from a
strongly coupled supersymmetric CFT with global symmetry SO(5) spontaneously
broken to SO(4), whilst the light generations and gauge fields are elementary
degrees of freedom whose couplings to the strong sector explicitly break the
global symmetry as well as supersymmetry. The presence of supersymmetry in the
strong sector may allow the compositeness scale to be raised to ~10 TeV without
fine tuning, consistent with the bounds from precision electro-weak
measurements and flavour physics. The supersymmetric flavour problem is also
solved. At low energies, this scenario reduces to the "More Minimal
Supersymmetric Standard Model" where only stops, Higgsinos and gauginos are
light and within reach of the LHC.Comment: 28 pages. v2 minor changes and Refs. adde
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