204 research outputs found
On the recently observed tensions in B decays
In the LHC era, the discovery of New Physics signals is the major
ambition of the high-energy physics community and flavor physics can provide access to new heavy particles (Kaluza-Klein modes, supersymmetric particles . . . ) in
complementary way with respect to direct searches. Signals of possible deviations
with respect to the Standard Model have been recently claimed both by BABAR
and LHCb through the analyses of specific semileptonic B-meson decays. First, I’ll
focus on semileptonic b → c decay with a τ lepton in the final states for which new
BABAR measurements are available, showing a deviation from the Standard Model
at 3.4 σ level. I study the effects of a new tensor operator in the effective weak
Hamiltonian on a set of observables, in semileptonic B → D(∗) modes as well as in
semileptonic B and Bs decays to excited charmed mesons. Moreover, I discuss the
phenomenology of the mode B → K∗�
+�
−, in the framework of a warped extradimensional model. Since a complete set of form factor independent observables
have been recently measured by the LHCb Collaboration, with few sizable deviations with respect to the Standard Model in some of them, it would be interesting
to put constraints on such a scenario from the FCNC transition b → s�+�−
On the recent anomalies in semileptonic B decays
Both BABAR and LHCb Collaborations have recently claimed signals of pos- sible deviations with respect to the Standard Model through the analyses of specific semileptonic B-meson decays. We firstly investigate the semileptonic b → c decay with a τ lepton in the final state for which new BABAR measurements are available, showing a deviation from the Standard Model at 3.4 σ level. We study the effects of a new ten- sor operator in the effective weak Hamiltonian on a set of observables, in semileptonic B → D (∗) modes as well as in semileptonic B and Bs decays to excited charmed mesons. Moreover, we discuss the phenomenology of the mode B → K ∗ � + � − , in the framework of a warped extra-dimensional model. Since a complete set of form factor almost in- dependent observables have been recently measured by the LHCb Collaboration, with few sizable deviations with respect to the Standard Model in some of them, it would be interesting to put constraints on such a scenario from the FCNC transition b → s� + � − . 1 Semileptonic B-meson decays with a τ lepton in the final state
On the anomalies recently discovered in semileptonic B decays to the third family
The ratios R(D-(*)) = B(B -> D-(*) t (nu) over bar (tau))/B(B -> D-(*) mu(nu) over bar (mu)) measured by BABAR Collaboration deviate from the standard model expectations; at the same time the purely leptonic channel B -> tau(nu) over bar (tau) has been found in better consistency with the standard model. We provide an attempt to reconcile these two experimental facts, within a New Physics Scenario, by adding a tensor operator in the effective weak Hamiltonian. We calculate the effects of such an operator in a set of observables, in semileptonic B -> D-(*) modes as well as in semileptonic B and B-s decays to excited positive parity charmed mesons
decays in the standard model and in scenarios with universal extra dimensions
We study the radiative decays, which are
important to investigate CP violation, and are also relevant to assess the role
of the exclusive modes induced by the transition to saturate
the inclusive decay rate. Moreover, these channels do not
display the same hierarchy as modes, for which the
decay into is enhanced with respect to one into . The
three-body radiative decays reverse the role: we find that this experimentally
observed behavior (although affected by a large uncertainty in the case of the
) is reproduced in the theoretical analysis. We compute a form factor, needed for this study, using light cone QCD sum rules, and
discuss a relation expected to hold in the large energy limit for the light
meson. Finally, we examine in two extensions of the
standard model with universal extra dimensions, to investigate the sensitivity
of this rare mode to such a kind of new physics effects.Comment: RevTeX, 17 pages, 7 figures. High resolution figures available upon
request. Matches the published versio
Mechanical weed control strategies for grain amaranth (Amaranthus cruentus L.)
Received: January 25th, 2022 ; Accepted: April 5th, 2022 ; Published: April 19th, 2022 ; Correspondence: [email protected], no herbicide is registered for grain amaranth in Europe, the United States
and South America. Hence, weed control must be addressed with alternative methods. Field trials
were conducted in 2018 and 2019 in Central Italy by comparing some mechanical weed control
treatments in grain amaranth (Amaranthus cruentus L.). In 2018, the five treatments were:
untreated control (T118), cutter hoeing (T218), flat share cuts and one central duck foot tine (T318),
flat share cuts and two central duck foot tines (T418), and three duck foot tines (T518). In 2019,
the five treatments were: untreated control (T119), three duck foot tines (T219), flex tine harrowing
(T319), flex tine harrowing plus finger weeding with red fingers (T419), and finger weeding with
red fingers (T520). In 2018, amaranth was a successful competitor against weeds from 40 days
after emergence (10 true leaf stage, corresponding to BBCH code 15). The competitive ability
was showed by excellent seed yields averaging 1.2 t ha-1
, for all treatments. This feature was also
confirmed to some degree in 2019. However, seed yield in 2019 was more strongly influenced
by treatment as well as by the lower emergence of plants. All the mechanical methods employed
can be effectively used for weed control in grain amaranth. Treatments with the flex tine harrower
and finger weeder negatively affected the plant density at harvest, necessitating further
optimization. However, combined mechanical strategies proved the most effective, especially in
controlling dicot weeds. There is a need to optimize strategies, with mechanical equipment, to
anticipate and improve the ground cover of amaranth. These strategies include selecting optimal
plant density and the correct distancing between the rows for easier mechanical control
Quantum dynamics of a high-finesse optical cavity coupled with a thin semi-transparent membrane
We study the quantum dynamics of the cavity optomechanical system formed by a
Fabry-Perot cavity with a thin vibrating membrane at its center. We first
derive the general multimode Hamiltonian describing the radiation pressure
interaction between the cavity modes and the vibrational modes of the membrane.
We then restrict the analysis to the standard case of a single cavity mode
interacting with a single mechanical resonator and we determine to what extent
optical absorption by the membrane hinder reaching a quantum regime for the
cavity-membrane system. We show that membrane absorption does not pose serious
limitations and that one can simultaneously achieve ground state cooling of a
vibrational mode of the membrane and stationary optomechanical entanglement
with state-of-the-art apparatuses.Comment: 14 pages, 7 figure
Exclusive b → s ν ν induced transitions in the RSc model
We study a set of exclusive B and Bs decay modes induced by the rare (Formula presented.) transition in the RSc model, an extra-dimensional extension of the standard model with warped 5D metric and extended gauge group. We discuss the role of correlations among the observables, and their importance for detecting the predicted small deviations from the standard model expectations
Exclusive b→sνν¯ induced transitions in the RS c model
We study a set of exclusive B and Bs decay modes induced by the rare b→sνν¯ transition in the RS c model, an extra-dimensional extension of the standard model with warped 5D metric and extended gauge group. We discuss the role of correlations among the observables, and their importance for detecting the predicted small deviations from the standard model expectations
Quantum dynamics of a vibrational mode of a membrane within an optical cavity
Optomechanical systems are a promising candidate for the implementation of
quantum interfaces for storing and redistributing quantum information. Here we
focus on the case of a high-finesse optical cavity with a thin vibrating
semitransparent membrane in the middle. We show that robust and stationary
optomechanical entanglement could be achieved in the system, even in the
presence of nonnegligible optical absorption in the membrane. We also present
some preliminary experimental data showing radiation-pressure induced optical
bistability.Comment: 6 pages, 2 figures. Work presented at the conference QCMC 2010 held
on 19-23 July 2010 at the University of Queensland, Brisbane, Australi
Optomechanical sideband cooling of a thin membrane within a cavity
We present an experimental study of dynamical back-action cooling of the
fundamental vibrational mode of a thin semitransparent membrane placed within a
high-finesse optical cavity. We study how the radiation pressure interaction
modifies the mechanical response of the vibrational mode, and the experimental
results are in agreement with a Langevin equation description of the coupled
dynamics. The experiments are carried out in the resolved sideband regime, and
we have observed cooling by a factor 350 We have also observed the mechanical
frequency shift associated with the quadratic term in the expansion of the
cavity mode frequency versus the effective membrane position, which is
typically negligible in other cavity optomechanical devices.Comment: 15 pages, 7 figure
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