15,659 research outputs found
On interference and non-interference in the SMEFT
We discuss interference in the limit in the
Standard Model Effective Field Theory (SMEFT). Dimension six operators that
contribute to scattering events can experience a suppression of interference effects
with the Standard Model in this limit. This occurs for subsets of phase space
in some helicity configurations. We show that approximating these scattering
events by on-shell scattering results for intermediate
unstable gauge bosons, and using the narrow width approximation, can miss
interference terms present in the full phase space. Such interference terms can
be uncovered using off-shell calculations as we explicitly show and calculate.
We also study the commutation relation between the SMEFT expansion and the
narrow width approximation, and discuss some phenomenological implications of
these results.Comment: 19 pages, 3 figures. Updated to published JHEP versio
Efficient inference of parsimonious phenomenological models of cellular dynamics using S-systems and alternating regression
The nonlinearity of dynamics in systems biology makes it hard to infer them
from experimental data. Simple linear models are computationally efficient, but
cannot incorporate these important nonlinearities. An adaptive method based on
the S-system formalism, which is a sensible representation of nonlinear
mass-action kinetics typically found in cellular dynamics, maintains the
efficiency of linear regression. We combine this approach with adaptive model
selection to obtain efficient and parsimonious representations of cellular
dynamics. The approach is tested by inferring the dynamics of yeast glycolysis
from simulated data. With little computing time, it produces dynamical models
with high predictive power and with structural complexity adapted to the
difficulty of the inference problem.Comment: 14 pages, 2 figure
Quantum Gravity Phenomenology, Lorentz Invariance and Discreteness
Contrary to what is often stated, a fundamental spacetime discreteness need
not contradict Lorentz invariance. A causal set's discreteness is in fact
locally Lorentz invariant, and we recall the reasons why. For illustration, we
introduce a phenomenological model of massive particles propagating in a
Minkowski spacetime which arises from an underlying causal set. The particles
undergo a Lorentz invariant diffusion in phase space, and we speculate on
whether this could have any bearing on the origin of high energy cosmic rays.Comment: 13 pages. Replaced version with corrected fundamental solution,
missing m's (mass) and c's (speed of light) added and reference on diffusion
on the three sphere changed. Note with additional references added and
addresses updated, as in published versio
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