1,551 research outputs found
Regularisation of Chiral Gauge Theories
This article gives a review of the topic of regularising chiral gauge
theories and is aimed at a general audience. It begins by clarifying the
meaning of chirality and goes on to discussing chiral projections in field
theory, parity violation and the distinction between vector and chiral field
theories. It then discusses the standard model of electroweak interactions from
the perspective of chirality. It also reviews at length the phenomenon of
anomalies in quantum field theories including the intuitive understanding of
anomalies based on the Dirac sea picture as given by Nielsen and Ninomiya. It
then raises the issue of a non-perturbative and constructive definition of the
standard model as well as the importance of such formulations. The second
Nielsen-Ninomiya theorem about the impossibility of regularising chiral gauge
theories under some general assumptions is also discussed. After a brief review
of lattice regularisation of field theories, it discusses the issue of fermions
on the lattice with special emphasis on the problem of species doubling. The
implications of these problems to introducing chiral fermions on the lattice as
well as the interpretations of anomalies within the lattice formulations and
the lattice Dirac sea picture are then discussed. Finally the difficulties of
formulating the standard model on the lattice are illustrated through detailed
discussions of the Wilson-Yukawa method, the domain wall fermions method and
the recently popular Ginsparg-Wilson method.Comment: LATEX, 26 pages, 7 fig
Dilepton asymmetries at factories in search of transitions
In order to detect the possible presence of
amplitudes in neutral meson decays, we consider the measurement of decay
time asymmetries involving like-sign dilepton events at the factories.Comment: 5 pages, latex, no fig
CPT violation in entangled B0-B0bar states and the demise of flavour tagging
We discuss the demise of flavour tagging due to the loss of the
particle-antiparticle identity of neutral B-mesons in the
Einstein-Podolsky-Rosen correlated states. Such a situation occurs in cases
where the CPT operator is ill-defined, as happens, for example, in quantum
gravity models with induced decoherence in the matter sector. The time
evolution of the perturbed B0-B0bar initial state, as produced in B-factories,
is sufficient to generate new two-body states. For flavour specific decays at
equal times, we discuss two definite tests of the two body entanglement: (i)
search for the would-be forbidden B0 B0 and B0bar B0bar states; (ii) deviations
from the indistinguishable probability between the permuted states B0bar B0 and
B0 B0bar.Comment: 12 pages LATEX, one eps figure incorporate
String-like behaviour of 4d SU(3) Yang-Mills flux tubes
We present here results on the fine structure of the static q\bar q potential
in d=4 SU(3) Yang-Mills theory. The potential is obtained from Polyakov loop
correlators having separations between 0.3 and 1.2 fermi. Measurements were
carried out on lattices of spatial extents of about 4 and 5.4 fermi. The
temporal extent was 5.4 fermi in both cases. The results are analyzed in terms
of the force between a q\bar q pair as well as in terms of a scaled second
derivative of the potential. The data is accurate enough to distinguish between
different effective string models and it seems to favour the expression for
ground state energy of a Nambu-Goto string.Comment: 9 pages in LaTeX with 2 figures and 2 tables in JHEP style. Replaced
to match with shortened published versio
Testing the Rule with Exclusive Semi-Leptonic Kaon Decays
We consider the possibility of violations of the selection rule at an appreciable level in {\it exclusive} semi-leptonic decays of
Kaons. At -Factories, intense Kaon beams will be available and will probe
among others, the semi-leptonic decays and in addition
to and could provide novel testing grounds for the
rule. In particular, the branching ratio of is non-negligible
and could be used to probe new phenomena associated with the violation of this
selection rule. Furthermore, we modify certain di-lepton event rate ratios and
asymmetries and time asymmetries that have been constructed by Dass and Sarma
for di-lepton events from Beon decays to test the at the
, to the Kaon system at the . We find that the large
width of the relative to that of plays an important role in
enhancing some of the time asymmetries.Comment: 10 pages, Plain Latex, To be run twice
Effects of Possible Transitions in Neutral Meson Decays}
We explore the possibility that the existing data on like-sign dileptons at
the resonance consist of events arising from mixing and also from transitions. The
consequences of these nonstandard transitions for certain time-asymmetries
which are likely to be measured at the factories are studied.Comment: {\LARGE \bf 10 pages, no figures, process using latex, TIFR/TH/93-5
Computational Drug Design against Ebola Virus Targeting Viral Matrix Protein VP30
Ebola viral disease (EVD) is a deadly infectious hemorrhagic viral fever caused by the Ebola virus with a high mortality rate. Until date, there is no effective drug or vaccination available to combat this condition. This study focuses on designing an effective antiviral drug for Ebola viral disease targeting viral protein 30 (VP30) of Ebola virus, highly required for transcription initiation. The lead molecules were screened for Lipinski rule of five, ADMET study following which molecular docking and bioactivity prediction was carried out. The compounds with the least binding energy were analyzed using interaction software. The results revealed that 6-Hydroxyluteolin and (-)-Arctigenin represent active lead compounds that inhibit the activity of VP30 protein and exhibits efficient pharmacokinetics. Both these compounds are plant-derived flavonoids and possess no known adverse effects on human health. In addition, they bind strongly to the predicted binding site centered on Lys180, suggesting that these two lead molecules can be imperative in designing a potential drug for EVD
Callus induction and regeneration of elite Indian maize inbreds
Five elite Indian maize inbreds namely; HKI1105, HKI1105, HKI335, CM300 and LM5 were evaluated for callus induction and regeneration. Immature embryos obtained 14 days after pollination were used as explants. Genotype, medium, type of auxin and their concentrations influenced callus induction. N6 medium supplemented with different concentration of 2,4-D (1, 2 and 3 mg/l) and Dicamba (1, 2 and 3 mg/l) were used for callus induction. N6 supplemented with 2 mg/l of 2,4-D has shown highest percentage of embryogenic callus induction. Among the five genotypes tested, CM300 gave highest percentage of embryogenic calli. CM300 and LM5 both have shown higher regeneration percentage of 12.22%.Key words: Maize, in-vitro culture and regeneration
On the spectrum of closed k=2 flux tubes in D=2+1 SU(N) gauge theories
We calculate the energy spectrum of a k=2 flux tube that is closed around a
spatial torus, as a function of its length l. We do so for SU(4) and SU(5)
gauge theories in 2 space dimensions. We find that to a very good approximation
the eigenstates belong to the irreducible representations of the SU(N) group
rather than just to its center, Z_N. We obtain convincing evidence that the
low-lying states are, for l not too small, very close to those of the
Nambu-Goto free string theory (in flat space-time). The correction terms appear
to be typically of O(1) in appropriate units, much as one would expect if the
bosonic string model were an effective string theory for the dynamics of these
flux tubes. This is in marked contrast to the case of fundamental flux tubes
where such corrections have been found to be unnaturally small. Moreover we
find that these corrections appear to be particularly small when the `phonons'
along the string have the same momentum, and large when their momentum is
opposite. This provides information about the detailed nature of the
interactions in the effective string theory. We have searched for, but not
found, extra states that would arise from the excitation of the massive modes
presumably associated with the non-trivial structure of the flux tube.Comment: 37 pages, 16 figures, minor changes to text and figure
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