339 research outputs found
Radiative corrections to decay amplitudes in lattice QCD
The precision of lattice QCD computations of many quantities has reached such
a precision that isospin-breaking corrections, including electromagnetism, must
be included if further progress is to be made in extracting fundamental
information, such as the values of Cabibbo-Kobayashi-Maskawa matrix elements,
from experimental measurements. We discuss the framework for including
radiative corrections in leptonic and semileptonic decays of hadrons, including
the treatment of infrared divergences. We briefly review isospin breaking in
leptonic decays and present the first numerical results for the ratio
in which these corrections have been
included. We also discuss the additional theoretical issues which arise when
including electromagnetic corrections to semileptonic decays, such as
decays. The separate definition of strong isospin-breaking effects
and those due to electromagnetism requires a convention. We define and advocate
conventions based on hadronic schemes, in which a chosen set of hadronic
quantities, hadronic masses for example, are set equal in QCD and in QCD+QED.
This is in contrast with schemes which have been largely used to date, in which
the renormalised and quark masses are set equal in QCD and in
QCD+QED in some renormalisation scheme and at some scale .Comment: Presented at the 36th Annual International Symposium on Lattice Field
Theory (Lattice2018), Michigan State University, July 22nd - 28th 201
The DM approach to semileptonic heavy-to-heavy and heavy-to-light decays
We present the results of the application of the Dispersion Matrix approach
to semileptonic heavy-to-heavy and heavy-to-light -meson decays. This method
allows to determine the hadronic form factors in a non-perturbative and
model-independent way. Starting from the available lattice results at large
values of the momentum transfer, we obtain the behaviour of the form factors in
their whole kinematical range without introducing any parameterization of their
momentum dependence. We will focus on the determination of the
Cabibbo-Kobayashi-Maskawa matrix elements and through the analysis of , , and decays. New
theoretical determinations of the Lepton Flavour Universality ratios relevant
for these transitions will be also presented, by focusing in particular on the
ratios.Comment: 9 pages, 3 figures. Proceedings for the 39th International Symposium
on Lattice Field Theory (Lattice 2022). arXiv admin note: substantial text
overlap with arXiv:2209.15413, arXiv:2205.13952; text overlap with
arXiv:2211.0723
Exclusive semileptonic -meson decays using lattice QCD and unitarity
We present the results of the application of the Dispersion Matrix approach
to exclusive semileptonic -meson decays. This method allows to determine the
hadronic form factors in a non-perturbative and completely model-independent
way. Starting from lattice results available at large values of the momentum
transfer, the behaviour of the form factors in their whole kinematical range is
obtained without introducing any parameterization of their momentum dependence.
We will focus on the determination of the Cabibbo-Kobayashi-Maskawa matrix
elements and through the analysis of
and decays.
New theoretical determinations of the Lepton Flavour Universality ratios
relevant for these transitions will be also presented.Comment: 8 pages, 5 figures, 2 tables; contribution to QCD@Work -
International Workshop on QCD - Theory and Experiment, 27 - 30 June 2022,
Lecce (Italy). arXiv admin note: substantial text overlap with
arXiv:2205.1395
, LFU and symmetry breaking in decays using Lattice QCD and Unitarity
We present an application of the unitarity-based dispersion matrix (DM)
approach to the extraction of the CKM matrix element from the
experimental data on the exclusive semileptonic decays. The DM method allows to achieve a non-perturbative,
model-independent determination of the momentum dependence of the semileptonic
form factors. Starting from lattice results available at large values of the
4-momentum transfer and implementing non-perturbative unitarity bound, the
behaviour of the form factors in their whole kinematical range is obtained
without introducing any explicit parameterization of their momentum dependence.
We consider the four exclusive semileptonic decays and extract from the experimental data for each
transition. The average over the four channels is , which is compatible with the latest inclusive determination at
level. We address also the issue of Lepton Flavour Universality by
computing pure theoretical estimates of the ratios of the branching
fractions for each channel, where is a light lepton. In the case of a
light spectator quark we obtain and ,
which are compatible with the corresponding experimental values within
. In the case of a strange spectator quark we obtain
and . The different
values for and may reflect symmetry breaking
effects, which seem to be present in some of the lattice form factors,
especially at large values of the recoil.Comment: Contribution to ICHEP-202
Las pelÃculas del ciclo
Angulo, J.; Martinelli, V. (1990). Las pelÃculas del ciclo. Nosferatu. Revista de cine. (4):52-78. http://hdl.handle.net/10251/40768.Importación Masiva5278
Isospin-breaking corrections to the muon magnetic anomaly in Lattice QCD
In this contribution we present a lattice calculation of the leading-order
electromagnetic and strong isospin-breaking (IB) corrections to the
quark-connected hadronic-vacuum-polarization (HVP) contribution to the
anomalous magnetic moment of the muon. The results are obtained adopting the
RM123 approach in the quenched-QED approximation and using the QCD gauge
configurations generated by the ETM Collaboration with dynamical
quarks, at three values of the lattice spacing (
fm), at several lattice volumes and with pion masses between and
MeV. After the extrapolations to the physical pion mass and to the
continuum and infinite-volume limits the contributions of the light, strange
and charm quarks are respectively equal to , and . At
leading order in and we obtain
, which is currently
the most accurate determination of the IB corrections to .Comment: Invited talk at the 9th International Workshop on Chiral Dynamics
(CD18), Durham, North Carolina (USA), 17-21 September 2018. 11 pages, 4
figure
HVP contribution of the light quarks to the muon including isospin-breaking corrections with Twisted-Mass fermions
We present a preliminary lattice calculation of the leading-order
electromagnetic and strong isospin-breaking corrections to the Hadronic Vacuum
Polarization (HVP) contribution of the light quarks to the anomalous magnetic
moment of the muon. The results are obtained in the quenched-
approximation using the gauge configurations generated by the European
Twisted Mass Collaboration (ETMC) with dynamical quarks, at
three values of the lattice spacing varying from to , at several lattice volumes and with pion masses in the range
Estimate of the chiral condensate in quenched lattice QCD
We determine the value of the quark condensate from quenched QCD simulations
on the lattice in two ways: (i) by using the GMOR formula; (ii) by comparing
the OPE prediction for the Goldstone pole contribution to the pseudoscalar
vertex, at moderately large momenta. In the MSbar scheme at mu=2 GeV, from the
GMOR formula we obtain = -(273 +/- 19 MeV)^3. We show that the value
extracted from the pseudoscalar vertex, = - (312 +/- 24 MeV)^3, is
consistent with the result obtained from the first (standard) method.Comment: 13 pages, 2 figures [version published in PLB
Radiative corrections to decay amplitudes in lattice QCD
The precision of lattice QCD computations of many quantities has reached such
a precision that isospin-breaking corrections, including electromagnetism, must
be included if further progress is to be made in extracting fundamental
information, such as the values of Cabibbo-Kobayashi-Maskawa matrix elements,
from experimental measurements. We discuss the framework for including
radiative corrections in leptonic and semileptonic decays of hadrons, including
the treatment of infrared divergences. We briefly review isospin breaking in
leptonic decays and present the first numerical results for the ratio
in which these corrections have been
included. We also discuss the additional theoretical issues which arise when
including electromagnetic corrections to semileptonic decays, such as
decays. The separate definition of strong isospin-breaking effects
and those due to electromagnetism requires a convention. We define and advocate
conventions based on hadronic schemes, in which a chosen set of hadronic
quantities, hadronic masses for example, are set equal in QCD and in QCD+QED.
This is in contrast with schemes which have been largely used to date, in which
the renormalised and quark masses are set equal in QCD and in
QCD+QED in some renormalisation scheme and at some scale
Effect of Quercetin on ABCC6 Transporter: Implication in HepG2 Migration.
Quercetin is a member of the flavonoid group of compounds, which is abundantly present in various dietary sources. It has excellent antioxidant properties and anti-inflammatory activity and is very effective as an anti-cancer agent against various types of tumors, both in vivo and in vitro. Quercetin has been also reported to modulate the activity of some members of the multidrug-resistance transporters family, such as P-gp, ABCC1, ABCC2, and ABCG2, and the activity of ecto-5'-nucleotidase (NT5E/CD73), a key regulator in some tumor processes such as invasion, migration, and metastasis. In this study, we investigated the effect of Quercetin on ABCC6 expression in HepG2 cells. ABCC6 is a member of the superfamily of ATP-binding cassette (ABC) transporters, poorly involved in drug resistance, whose mutations cause pseudoxanthoma elasticum, an inherited disease characterized by ectopic calcification of soft connective tissues. Recently, it has been reported that ABCC6 contributes to cytoskeleton rearrangements and HepG2 cell motility through purinergic signaling. Gene and protein expression were evaluated by quantitative Reverse-Transcription PCR (RT-qPCR) and western blot, respectively. Actin cytoskeleton dynamics was evaluated by laser confocal microscopy using fluorophore-conjugated phalloidin. Cell motility was analyzed by an in vitro wound-healing migration assay. We propose that ABCC6 expression may be controlled by the AKT pathway as part of an adaptative response to oxidative stress, which can be mitigated by the use of Quercetin-like flavonoids
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