Abhijit Kumar Saha

Higgs vacuum stability and modified chaotic inflation

The issue of electroweak vacuum stability is studied in presence of a scalar field which participates in modifying the minimal chaotic inflation model. It is shown that the threshold effect on the Higgs quartic coupling originating from the Higgs–inflaton sector interaction can essentially make the electroweak vacuum stable up to the Planck scale. On the other hand we observe that the new physics parameters in this combined framework are enough to provide deviation from the minimal chaotic inflation predictions so as to keep it consistent with recent observation by Planck 2015.

A dynamic modification to sneutrino chaotic inflation

A bstractWe consider a right-handed scalar neutrino as the inflaton which carries a gravitational coupling with a supersymmetric QCD sector responsible for breaking supersymmetry dynamically. The framework suggests an inflaton potential which is a deformed version of the quadratic chaotic inflation leading to a flatter potential. We find that this deformation results a sizable tensor to scalar ratio which falls within the allowed region by PLANCK 2015. At the same time supersymmetry breaking at the end of inflation can naturally be induced in this set-up. The symmetries required to construct the framework allows the neutrino masses and mixing to be of right order.

Phenolic Ester Mediated Oligopeptide Synthesis Promoted by HOBt

Although substituted phenolic ester mediated peptide synthesis is an efficient and well established method, the same via totally unsubstituted phenyl ester is not preferred due to the extremely slow rate of aminolysis. We have investigated the scope of the unsubstituted phenyl ester as an intermediate in peptide bond formation and found that it may be useful for the design of chemoselective peptide ligation when HOBt is used as an acyl transfer catalyst. The scope of HOBt catalyzed, oxo ester mediated ligation is explored for the synthesis of oligopeptides containing a cysteine, serine and threonine at the N-terminus of the ligating peptide.

Stabilizing Electroweak Vacuum Through Modified Chaotic Inflation

We study the issue of electroweak vacuum stability in presence of a scalar field which modifies the minimal chaotic inflation model successfully. We find the required parameter space for which absolute higgs vacuum stability can be achieved.

Modulation of Aggregation Propensity of Aβ38 by Site Specific Multiple Proline Substitution

Proline with its unique geometrical feature generates turn in the peptide backbone. Therefore, aggregation potential of Aβ38 can be modulated by insertion of proline at specific positions. Although site specific proline mutation is reported, effect of multiple proline substitution on aggregation potential is still not demonstrated. Therefore, Aβ38, a single proline substituted variant, V18P-Aβ38, a double proline substituted variant, V18P-I31P-Aβ38 and a triple proline substituted version, V12P-V18P-I31P-Aβ38 were synthesized and their aggregation potential were studied. The proline mutants found to have higher solubility and slower aggregation kinetics. The double mutated version was relatively less aggregation prone than its single mutated version. Such analogues can be useful for designing new β sheet breaker peptides, studying the mechanism of aggregation and structural analyses.