343 research outputs found
Proteasome inhibitors as a possible therapy for SARS-CoV-2
The COVID-19 global pandemic is caused by SARS-CoV-2, and represents an urgent medical and social issue. Unfortunately, there is still not a single proven effective drug available, and therefore, current therapeutic guidelines recommend supportive care including oxygen administration and treatment with antibiotics. Recently, patients have been also treated with off-label therapies which comprise antiretrovirals, anti-inflammatory compounds, antiparasitic agents and plasma from convalescent patients, all with controversial results. The ubiquitin–proteasome system (UPS) is important for the maintenance of cellular homeostasis, and plays a pivotal role in viral replication processes. In this review, we discuss several aspects of the UPS and the effects of its inhibition with particular regard to the life cycle of the coronaviruses (CoVs). In fact, proteasome inhibition by various chemical compounds, such as MG132, epoxomycin and bortezomib, may reduce the virus entry into the eucariotic cell, the synthesis of RNA, and the subsequent protein expression necessary for CoVs. Importantly, since UPS inhibitors reduce the cytokine storm associated with various inflammatory conditions, it is reasonable to assume that they might be repurposed for SARS-CoV-2, thus providing an additional tool to counteract both virus replication as well as its most deleterious consequences triggered by abnormal immunological response
Deconstructing Non-Abelian Gauge Theories at One Loop
Deconstruction of 5D Yang-Mills gauge theories is studied in next-to-leading
order accuracy. We calculate one-loop corrections to the mass spectrum of the
non-linear gauged sigma-model, which is the low energy effective theory of the
deconstructed theory. Renormalization is carried out following the standard
procedure of effective field theories. The relation between the radius of the
compactified fifth dimension and the symmetry breaking scale of the non-linear
sigma-model is modified by radiative corrections. We demonstrate that one can
match the low lying spectrum of the gauge boson masses of the effective 4D
gauged non-linear sigma-model to the Kaluza-Klein modes of the 5D theory at
one-loop accuracy
Limits on a Composite Higgs Boson
Precision electroweak data are generally believed to constrain the Higgs
boson mass to lie below approximately 190 GeV at 95% confidence level. The
standard Higgs model is, however, trivial and can only be an effective field
theory valid below some high energy scale characteristic of the underlying
non-trivial physics. Corrections to the custodial isospin violating parameter T
arising from interactions at this higher energy scale dramatically enlarge the
allowed range of Higgs mass. We perform a fit to precision electroweak data and
determine the region in the (m_H, Delta T) plane that is consistent with
experimental results. Overlaying the estimated size of corrections to T arising
from the underlying dynamics, we find that a Higgs mass up to 500 GeV is
allowed. We review two composite Higgs models which can realize the possibility
of a phenomenologically acceptable heavy Higgs boson. We comment on the
potential of improvements in the measurements of m_t and M_W to improve
constraints on composite Higgs models.Comment: 9 pages, 2 eps figures. Shortened for PRL; some references elminate
The Electroweak Chiral Lagrangian and CP-Violating Effects in Technicolor Theories
We estimate the CP-violating and anomalous form factors,
arising from CP-violating interactions in extended technicolor theories, and
discuss their future experimental detectability. The electric dipole moment of
the boson is found to be as large as {\cal O}(10^{-21}) \; \mbox{e cm}.
We connect the CP-odd and couplings to the corresponding
CP-violating electroweak chiral lagrangian operators. The electric dipole
moments of the neutron and the electron in technicolor theories are estimated
to be as large as {\cal O}(10^{-26}) \; \mbox{e cm} and {\cal O}(10^{-29})
\; \mbox{e cm} respectively. We also suggest the potential to observe large
CP-violating technicolor effects in the decay .Comment: 34 pages, YCTP-P9-94, LaTex. (minor changes in wording and notation,
the figures are appended at the end as one postscript file
Analyticity, Crossing Symmetry and the Limits of Chiral Perturbation Theory
The chiral Lagrangian for Goldstone boson scattering is a power series
expansion in numbers of derivatives. Each successive term is suppressed by
powers of a scale, , which must be less than of order where is the Goldstone boson decay constant and is the
number of flavors. The chiral expansion therefore breaks down at or below . We argue that the breakdown of the chiral expansion is
associated with the appearance of physical states other than Goldstone bosons.
Because of crossing symmetry, some ``isospin'' channels will deviate from their
low energy behavior well before they approach the scale at which their low
energy amplitudes would violate unitarity. We argue that the estimates of
``oblique'' corrections from technicolor obtained by scaling from QCD are
untrustworthy.Comment: harvmac, 18 pages (3 figures), HUTP-92/A025, BUHEP-92-18, new version
fixes a TeX problem in little mod
Low-Energy Constraints on New Physics Revisited
It is possible to place constraints on non-Standard-Model gauge-boson
self-couplings and other new physics by studying their one-loop contributions
to precisely measured observables. We extend previous analyses which constrain
such nonstandard couplings, and we present the results in a compact and
transparent form. Particular attention is given to comparing results for the
light-Higgs scenario, where nonstandard effects are parameterized by an
effective Lagrangian with a linear realization of the electroweak symmetry
breaking sector, and the heavy-Higgs/strongly interacting scenario, described
by the electroweak chiral Lagrangian. The constraints on nonstandard
gauge-boson self-couplings which are obtained from a global analysis of
low-energy data and LEP/SLC measurements on the Z pole are updated and improved
from previous studies. Replaced version: tables and figures of Section VIb
recalculated. There were roundoff problems, especially in Fig. 8. Text
unchanged.Comment: \documentstyle[preprint,aps,floats,psfig]{revtex}, 10 figures,
postscript version available from ftp://ftp.kek.jp/kek/preprints/TH/TH-51
Complete analysis on the next-to-leading order supersymmetric QCD corrections to mixing
We present a complete next-to-leading-order calculation of the QCD
corrections to () mixing in the framework of the
minimal flavor violating (MFV) supersymmetry. We take into account the
contributions from the gluino and find that the gluino-mediated corrections
modify the LO result obviously even when the mass of gluino . In general, one cannot neglect gluino contributions.Comment: 91 pages + 11 eps figures, publication version in PR
The Effective Electroweak Chiral Lagrangian: The Matter Sector
We parametrize in a model-independent way possible departures from the
minimal Standard Model predictions in the matter sector. We only assume the
symmetry breaking pattern of the Standard Model and that new particles are
sufficiently heavy so that the symmetry is non-linearly realized. Models with
dynamical symmetry breaking are generically of this type. We review in the
effective theory language to what extent the simplest models of dynamical
breaking are actually constrained and the assumptions going into the comparison
with experiment. Dynamical symmetry breaking models can be approximated at
intermediate energies by four-fermion operators. We present a complete
classification of the latter when new particles appear in the usual
representations of the group as well as a partial
classification in the general case. We discuss the accuracy of the four-fermion
description by matching to a simple `fundamental' theory. The coefficients of
the effective lagrangian in the matter sector for dynamical symmetry breaking
models (expressed in terms of the coefficients of the four-quark operators) are
then compared to those of models with elementary scalars (such as the minimal
Standard Model). Contrary to a somewhat widespread belief, we see that the sign
of the vertex corrections is not fixed in dynamical symmetry breaking models.
This work provides the theoretical tools required to analyze, in a rather
general setting, constraints on the matter sector of the Standard Model.Comment: Latex, 45 pages, 8 eps figures. Sections 5, 6 and 9 have been
rewritten to clarify the contents. Some mistakes and typos have been
corrected. Two references have been added. Figures 7 and 8 have been modifie
Top-Charm Associated Production in High Energy Collisions
The possibility of exploring the flavor changing neutral current
couplings in the production vertex for the reaction \epem\to
t\bar c + \bar tc is examined. Using a model independent parameterization for
the effective Lagrangian to describe the most general three-point interactions,
production cross sections are found to be relatively small at LEP II, but
potentially sizeable at higher energy \epem colliders. The kinematic
characteristics of the signal are studied and a set of cuts are devised for
clean separation of the signal from background. The resulting sensitivity to
anomalous flavor changing couplings at LEP II with an integrated luminosity of
pb is found to be comparable to their present indirect
constraints from loop processes, while at higher energy colliders with
TeV center-of-mass energy and 50-200 fb luminosity, one expects to reach
a sensitivity at or below the percentage level.Comment: Latex, 22 page
Contributions of LEP1.5, LEP2 and linear-collider data to indirect constraints on non-Abelian gauge-boson couplings
It is possible to place direct constraints on WW-photon and WWZ couplings by
studying their tree-level contributions to the process e^+e^- ---> W^+W^-.
However, these couplings also contribute at the loop level to e^+e^- ---> f
fbar processes where `f' is any Standard-Model fermion. In this paper the
available LEP1.5 and LEP2 data, the anticipated LEP2 data and possible linear
collider data for these latter processes is combined with low-energy and Z-pole
data to place indirect constraints on nonstandard WW-photon and WWZ couplings.
The direct and indirect constraints are then compared. An effective Lagrangian
is used to describe the new physics. In order that the implications of this
analysis are as broad as possible, both the light-Higgs scenario, described by
an effective Lagrangian with a linear realization of the symmetry-breaking
sector, and the strongly interacting scenario, described by the electroweak
chiral Lagrangian, are considered.Comment: \documentstyle[preprint,aps,floats,psfig]{revtex}, 4 figures,
postscript version available from ftp://ftp.kek.jp/kek/preprints/TH/TH-53
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