81 research outputs found
Aerobic bacterial profile and their antimicrobial sensitivity pattern in patients of otitis media with ear discharge
Background: The average prevalence of Chronic suppurative otitis media (CSOM) in India is 5.2%. It is more prevalent due to various predisposing factors such as malnutrition, overcrowding, poor hygiene, inadequate health care, and recurrent upper respiratory tract infection. In recent years, there is increased preponderance of multi drug resistant organisms due to the irrational use of antibiotics, making treatment of CSOM more difficult.Methods: Samples from 100 subjects of uncomplicated CSOM who presented to the Oto-Rhino-Laryngology outpatient department of our hospital were collected. Aerobic bacterial profile and its Antimicrobial susceptibility were studied by conventional methods. Results were compiled and evaluated by descriptive statistics and inferential statistics.Results: Pseudomonas aeruginosa (50.7%) and Staphylococcus aureus (19.04%) were the predominant isolates in our study. Aminoglycosides and Fluoroquinolones were found to be effective first line drugs, followed by Carbapenems.Conclusions: These antibiotics can be used to prevent the life-long complications of CSOM. Timely culture and sensitivity helps in the management of these cases.
Light GUT Triplets and Yukawa Splitting
Triplet-mediated proton decay in Grand Unified Theories (GUTs) is usually
suppressed by arranging a large triplet mass. Here we explore instead a
mechanism for suppressing the couplings of the triplets to the first and second
generations compared to the Yukawa couplings, so that the triplets' mass can be
below the GUT scale. This mechanism is based on a ``triplet symmetry'' in the
context of product-group GUTs. We study two possibilities. One, which requires
the top Yukawa to arise from a non-renormalizable operator at the GUT scale, is
that all triplet couplings to matter are negligible, so that the triplets can
be at the weak scale. The second is that some triplet couplings, and in
particular and , are equal to the corresponding
Yukawa couplings. This would give a distinct signature of grand unification if
the triplets were sufficiently light. However, we derive a model-independent
bound on the triplet mass in this case, which is at least 10GeV. Finally,
we construct a GUT model based on Yukawa splitting, with the triplets at
10GeV, as required for coupling unification to work.Comment: 5 pages, Revtex4, 1 EPS figure. To appear in PRD: Minor changes.
Appendix droppe
Large Electric Dipole Moments of Heavy Neutrinos
In many models of CP violation, the electric dipole moment (EDM) of a heavy
charged or neutral lepton could be very large. We present an explicit model in
which a heavy neutrino EDM can be as large as e-cm, or even a factor
of ten larger if fine-tuning is allowed, and use an effective field theory
argument to show that this result is fairly robust. We then look at the
production cross section for these neutrinos, and by rederiving the Bethe-Block
formula, show that they could leave an ionization track. It is then noted that
the first signature of heavy neutrinos with a large EDM would come from
, leading to a very large rate for single photon plus
missing energy events, and the rate and angular distribution are found.
Finally, we look at some astrophysical consequences, including whether these
neutrinos could constitute the UHE cosmic rays and whether their decays in the
early universe could generate a net lepton asymmetry.Comment: 22 pages, 9 figure
Minimal Supersymmetric Pati-Salam Theory: Determination of Physical Scales
We systematically study the minimal supersymmetric Pati-Salam theory, paying
special attention to the unification constraints. We find that the SU(4)_c
scale M_c and the Left-Right scale M_R lie in the range 10^{10} GeV < M_c <
10^{14} GeV, 10^{3} GeV < M_R <10^{10} GeV (with single-step breaking at
10^{10} GeV), giving a potentially accessible scale of parity breaking. The
theory includes the possibility of having doubly-charged supermultiplets at the
supersymmetry breaking scale; color octet states with mass of order M_R^2/M_c;
magnetic monopoles of intermediate mass that do not conflict with cosmology,
and a 'clean' (type I) form for the see-saw mechanism of neutrino mass.Comment: 5 page
Model Building with Gauge-Yukawa Unification
In supersymmetric theories with extra dimensions, the Higgs and matter fields
can be part of the gauge multiplet, so that the Yukawa interactions can arise
from the gauge interactions. This leads to the possibility of gauge-Yukawa
coupling unification, g_i=y_f, in the effective four dimensional theory after
the initial gauge symmetry and the supersymmetry are broken upon orbifold
compactification. We consider gauge-Yukawa unified models based on a variety of
four dimensional symmetries, including SO(10), SU(5), Pati-Salam symmetry,
trinification, and the Standard Model. Only in the case of Pati-Salam and the
Standard Model symmetry, we do obtain gauge-Yukawa unification. Partial
gauge-Yukawa unification is also briefly discussed.Comment: 23 page
The Formation of Cosmic Structures in a Light Gravitino Dominated Universe
We analyse the formation of cosmic structures in models where the dark matter
is dominated by light gravitinos with mass of eV -- 1 keV, as predicted
by gauge-mediated supersymmetry (SUSY) breaking models. After evaluating the
number of degrees of freedom at the gravitinos decoupling (), we compute
the transfer function for matter fluctuations and show that gravitinos behave
like warm dark matter (WDM) with free-streaming scale comparable to the galaxy
mass scale. We consider different low-density variants of the WDM model, both
with and without cosmological constant, and compare the predictions on the
abundances of neutral hydrogen within high-redshift damped Ly-- systems
and on the number density of local galaxy clusters with the corresponding
observational constraints. We find that none of the models satisfies both
constraints at the same time, unless a rather small value (\mincir
0.4) and a rather large Hubble parameter (\magcir 0.9) is assumed.
Furthermore, in a model with warm + hot dark matter, with hot component
provided by massive neutrinos, the strong suppression of fluctuation on scales
of \sim 1\hm precludes the formation of high-redshift objects, when the
low-- cluster abundance is required. We conclude that all different variants
of a light gravitino DM dominated model show strong difficulties for what
concerns cosmic structure formation.
This gives a severe cosmological constraint on the gauge-mediated SUSY
breaking scheme.Comment: 28 pages,Latex, submitted for publication to Phys.Rev.
Primordial Nucleosynthesis Constraints on Z' Properties
In models involving new TeV-scale Z' gauge bosons, the new U(1)' symmetry
often prevents the generation of Majorana masses needed for a conventional
neutrino seesaw, leading to three superweakly interacting ``right-handed''
neutrinos nu_R, the Dirac partners of the ordinary neutrinos. These can be
produced prior to big bang nucleosynthesis by the Z' interactions, leading to a
faster expansion rate and too much ^4He. We quantify the constraints on the Z'
properties from nucleosynthesis for Z' couplings motivated by a class of E_6
models parametrized by an angle theta_E6. The rate for the annihilation of
three approximately massless right-handed neutrinos into other particle pairs
through the Z' channel is calculated. The decoupling temperature, which is
higher than that of ordinary left-handed neutrinos due to the large Z' mass, is
evaluated, and the equivalent number of new doublet neutrinos Delta N_nu is
obtained numerically as a function of the Z' mass and couplings for a variety
of assumptions concerning the Z-Z' mixing angle and the quark-hadron transition
temperature T_c. Except near the values of theta_E6 for which the Z' decouples
from the right-handed neutrinos, the Z' mass and mixing constraints from
nucleosynthesis are much more stringent than the existing laboratory limits
from searches for direct production or from precision electroweak data, and are
comparable to the ranges that may ultimately be probed at proposed colliders.
For the case T_c = 150 MeV with the theoretically favored range of Z-Z'
mixings, Delta N_nu 4.3 TeV for any value of theta_E6. Larger
mixing or larger T_c often lead to unacceptably large Delta N_nu except near
the nu_R decoupling limit.Comment: 22 pages, 5 figures; two additional references adde
Dark matter and Colliders searches in the MSSM
We study the complementarity between dark matter experiments (direct
detection and indirect detections) and accelerator facilities (the CERN LHC and
a TeV Linear Collider) in the framework of the
constrained Minimal Supersymmetric Standard Model (MSSM). We show how
non--universality in the scalar and gaugino sectors can affect the experimental
prospects to discover the supersymmetric particles. The future experiments will
cover a large part of the parameter space of the MSSM favored by WMAP
constraint on the relic density, but there still exist some regions beyond
reach for some extreme (fine tuned) values of the supersymmetric parameters.
Whereas the Focus Point region characterized by heavy scalars will be easily
probed by experiments searching for dark matter, the regions with heavy
gauginos and light sfermions will be accessible more easily by collider
experiments. More informations on both supersymmetry and astrophysics
parameters can be thus obtained by correlating the different signals.Comment: 25 pages, 10 figures, corrected typos and reference adde
Search for neutrinoless decays tau -> 3l
We have searched for neutrinoless tau lepton decays into three charged
leptons using an 87.1 fb^{-1} data sample collected with the Belle detector at
the KEKB e^+e^- collider. Since the number of signal candidate events is
compatible with that expected from the background, we set 90% confidence level
upper limits on the branching fractions in the range (1.9-3.5) x 10^{-7} for
various decay modes tau -> l l l where l represents e or mu.Comment: 12 pages, 4figure
- …