373 research outputs found
Lab-frame observables for probing the top-Higgs interaction
We investigate methods to explore the CP nature of the coupling
at the LHC, focusing on associated production of the Higgs with a
pair. We first discuss the constraints implied by low-energy observables and by
the Higgs-rate information from available LHC data, emphasizing that they
cannot provide conclusive evidence on the nature of this coupling. We then
investigate kinematic observables that could probe the coupling
directly, in particular quantities that can be constructed out of just
lab-frame kinematics. We define one such observable by exploiting the fact that
spin correlations do also carry information about the CP-nature of
the coupling. Finally, we introduce a CP-odd quantity and a
related asymmetry, able to probe CP violation in the coupling and
likewise constructed out of lab-frame momenta only.Comment: 32 pages, updated with latest data from ATLAS and references adde
Responsive Urban Models by Processing Sets of Heterogeneous Data
This paper presents some steps in experimentation aimed at describing urban spaces made following the series of earthquakes that affected a vast area of central Italy starting on 24 August 2016. More specifically, these spaces pertain to historical centres of limited size and case studies that can be called "problematic" (due to complex morphological and settlement conditions, because they are difficult to access, or because they have been affected by calamitous events, etc.). The main objectives were to verify the use of sets of heterogeneous data that are already largely available to define a workflow and develop procedures that would allow some of the steps to be automated as much as possible. The most general goal was to use the experimentation to define a methodology to approach the problem aimed at developing descriptive responsive models of the urban space, that is, morphological and computer-based models capable of being modified in relation to the constantly updated flow of input data
Bs to l+ l- gamma as a Test of Lepton Flavor Universality
We discuss a number of strategies to reduce the theoretical error, and make such a measurement a new
probe of the interactions that are interesting in the light of present-day
flavor discrepancies. In particular, for low di-lepton invariant mass we
propose to exploit the close parenthood between and the measured . For high , conversely, we exploit the fact that the decay is
dominated by two form-factor combinations, plus contributions from broad
charmonium that we model accordingly. We construct the ratio , akin
to and likewise sensitive to lepton-universality violation. Provided the
two rates in this ratio are integrated in a suitable region that minimises
bremsstrahlung contributions while maximising statistics, the ratio is very
close to unity and the form-factor dependence cancels to an extent that makes
it a new valuable probe of lepton-universality violating contributions in the
effective Hamiltonian. We finally speculate on additional ideas to extract
short-distance information from resonance regions, which are theoretically
interesting but statistically limited at present.Comment: 21 pages, 4 figures. v4: in appendix removed equation already present
in main tex
The neutron electric dipole form factor in the perturbative chiral quark model
We calculate the electric dipole form factor of the neutron in a perturbative
chiral quark model, parameterizing CP-violation of generic origin by means of
effective electric dipole moments of the constituent quarks and their
CP-violating couplings to the chiral fields. We discuss the relation of these
effective parameters to more fundamental ones such as the intrinsic electric
and chromoelectric dipole moments of quarks and the Weinberg parameter. From
the existing experimental upper limits on the neutron EDM we derive constraints
on these CP-violating parameters.Comment: 20 pages, 3 figure
Gauged flavour symmetry for the light generations
We study the phenomenology of a model where an SU(2)^3 flavour symmetry
acting on the first two generation quarks is gauged and Yukawa couplings for
the light generations are generated by a see-saw mechanism involving heavy
fermions needed to cancel flavour-gauge anomalies. We find that, in constrast
to the SU(3)^3 case studied in the literature, most of the constraints related
to the third generation, like electroweak precision bounds or B physics
observables, can be evaded, while characteristic collider signatures are
predicted.Comment: 16 pages, 3 figure
D*-->Dpi and D*-->Dgamma decays: Axial coupling and Magnetic moment of D* meson
The axial coupling and the magnetic moment of D*-meson or, more specifically,
the couplings g(D*Dpi) and g(D*Dgamma), encode the non-perturbative QCD effects
describing the decays D*-->Dpi and D*-->Dgamma. We compute these quantities by
means of lattice QCD with Nf=2 dynamical quarks, by employing the Wilson
("clover") action. On our finer lattice (a=0.065 fm) we obtain: g(D*Dpi)=20 +/-
2, and g(D0*D0gamma)=[2.0 +/- 0.6]/GeV. This is the first determination of
g(D0*D0gamma) on the lattice. We also provide a short phenomenological
discussion and the comparison of our result with experiment and with the
results quoted in the literature.Comment: 22 pages, 3 figure
The inhibition of the highly expressed miR-221 and miR-222 impairs the growth of prostate carcinoma xenografts in mice
MiR-221 and miR-222 are two highly homologous microRNAs whose upregulation has been recently described in several types of human tumors, for some of which their oncogenic role was explained by the discovery of their target p27, a key cell cycle regulator. We previously showed this regulatory relationship in prostate carcinoma cell lines in vitro, underlying the role of miR-221/222 as inducers of proliferation and tumorigenicity
Left-right symmetry at LHC and precise 1-loop low energy data
Despite many tests, even the Minimal Manifest Left-Right Symmetric Model
(MLRSM) has never been ultimately confirmed or falsified. LHC gives a new
possibility to test directly the most conservative version of left-right
symmetric models at so far not reachable energy scales. If we take into account
precise limits on the model which come from low energy processes, like the muon
decay, possible LHC signals are strongly limited through the correlations of
parameters among heavy neutrinos, heavy gauge bosons and heavy Higgs particles.
To illustrate the situation in the context of LHC, we consider the "golden"
process . For instance, in a case of degenerate heavy neutrinos
and heavy Higgs masses at 15 TeV (in agreement with FCNC bounds) we get
fb at TeV which is consistent with muon
decay data for a very limited masses in the range (3008 GeV, 3040 GeV).
Without restrictions coming from the muon data, masses would be in the
range (1.0 TeV, 3.5 TeV). Influence of heavy Higgs particles themselves on the
considered LHC process is negligible (the same is true for the light, SM
neutral Higgs scalar analog). In the paper decay modes of the right-handed
heavy gauge bosons and heavy neutrinos are also discussed. Both scenarios with
typical see-saw light-heavy neutrino mixings and the mixings which are
independent of heavy neutrino masses are considered. In the second case heavy
neutrino decays to the heavy charged gauge bosons not necessarily dominate over
decay modes which include only light, SM-like particles.Comment: 16 pages, 10 figs, KL-KS and new ATLAS limits taken into accoun
Analysis of the form factors with light-cone QCD sum rules
In this work, we study the four form-factors , ,
and of the in the framework of the
light-cone QCD sum rules approach up to twist-6 three valence quark light-cone
distribution amplitudes. The is the basic input parameter in
extracting the CKM matrix element from the hyperon decays.
The four form-factors , , and at
intermediate and large momentum transfers with have significant
contributions from the end-point (soft) terms. The numerical values of the four
form-factors , , and are compatible with the
experimental data and theoretical calculations (in magnitude); although the
uncertainties are large.Comment: 16 pages, 4 figures, second version, typos corrected, the article is
published in "J. Phys. G34 (2007) 493-504" not in "J. Phys. G34 (2007)
335-346
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