qq' -> qq': a second look at the IR divergences

The transport properties of the quark-gluon plasma is important both from the point of view of the astrophysical systems and the heavy ion collisions. Therefore, accurate calculations of the elastic scattering cross-sections of $qq' \to qq'$ and q\qbar' \to q\qbar' processes are required. At the tree-diagram level exchange of massless gluons leads to divergent cross sections for such processes. An effective way to remove the infrared divergence is to introduce a Debye mass as an infrared regulator into the gluon propagator for the thermal gluons. In this work we find that at the two-gluon exchange level such a technique fails to remove the divergences. In a chiral symmetry broken phase the mass could be introduced following the standard procedure which cures the divergence. But in a chirally symmetric phase chiral invariant mass of the fermions needs to be considered.Comment: 4 pages, latex, 1 figur

Energy Cost of Creating Quantum Coherence

We consider the physical situations where the resource theories of coherence and thermodynamics play competing roles. In particular, we study the creation of quantum coherence using unitary operations with limited thermodynamic resources. We first find the maximal coherence that can be created under unitary operations starting from a thermal state and find explicitly the unitary transformation that creates the maximal coherence. Since coherence is created by unitary operations starting from a thermal state, it requires some amount of energy. This motivates us to explore the trade-off between the amount of coherence that can be created and the energy cost of the unitary process. We find the maximal achievable coherence under the constraint on the available energy. Additionally, we compare the maximal coherence and the maximal total correlation that can be created under unitary transformations with the same available energy at our disposal. We find that when maximal coherence is created with limited energy, the total correlation created in the process is upper bounded by the maximal coherence and vice versa. For two qubit systems we show that there does not exist any unitary transformation that creates maximal coherence and maximal total correlation simultaneously with a limited energy cost.Comment: 8 pages, Accepted for publication in Physical Review

Two-dimensional band structure in honeycomb metal-organic frameworks

Metal-organic frameworks (MOFs) are an important class of materials that present intriguing opportunities in the fields of sensing, gas storage, catalysis, and optoelectronics. Very recently, two-dimensional (2D) MOFs have been proposed as a flexible material platform for realizing exotic quantum phases including topological and anomalous quantum Hall insulators. Experimentally, direct synthesis of 2D MOFs has been essentially confined to metal substrates, where the interaction with the substrate masks the intrinsic electronic properties of the MOF. Here, we demonstrate synthesis of 2D honeycomb metal-organic frameworks on a weakly interacting epitaxial graphene substrate. Using low-temperature scanning tunneling microscopy (STM) and atomic force microscopy (AFM) complemented by density-functional theory (DFT) calculations, we show the formation of 2D band structure in the MOF decoupled from the substrate. These results open the experimental path towards MOF-based designer quantum materials with complex, engineered electronic structures

SOME CHARACTERIZATIONS OF α-COSYMPLECTIC MANIFOLDS ADMITTING ∗-CONFORMAL RICCI SOLITIONS

The object of the present paper is to give some characterizations of α-cosymplectic manifolds admitting ∗-conformal Ricci solitons. Such manifolds with gradient ∗-conformal Ricci solitons have also been considere

Metallurgical Investigation on the Effect of BZL Welding of LPTR Blase Shrouded Tips of Aero Engines

BZL welding and assembly procedure could be an area of concern for failure of LPTR blades of acro engines that might have caused number of accidents of aircrafts. So the present investigation is aimed to understand the effect of number of times BZL welding performed on microstructure and properties of the LPTR blades shrouded tips.Hence four numbers of LPTR blades of R-29 aero engine with different number of times BZL welding carried out were investigated and the results were presented. The increase in grain size of the LPTR blade tip was observed with number of times BZL welding was carried out. Rounding of y' (gamma prime) phase is occurring with BZL weldings. The dissolution of y' (gamma prime) phase near interface between base metal and weld metal is observed. However, there is not much appreciable change in hardness of the blade tips with number of times BZL weldings performed were observed. Moreover all the BZL welded blade tips have compressive residual stress

Information Retrieval Techniques Used by the Midnapore College (Autonomous) Library Users: A Study

Paper aims to present the results of a survey conducted to determine the information retrieval techniques used by the teachers and students of Midnapore College library, India as a result of the questionnaire-based survey conducted at the library. Out of 100 samples of the questionnaire distributed 93 completed and received for analysis. Study reveals that a significant number of users search information regarding the library material through OPAC despite encountering problems. Lack of basic skills among users was found to be the major reason for not utilizing full features of OPAC and the other reasons are improper query formulation and non use of search operators while surf the web. It is suggested that library should organize quality instruction programmes to improve knowledge and skills of the users

Characterization of Tempering Behaviour of Modified 9Cr-1Mo Steel by Ultrasonic Lamb wave Mixing

This work demonstrates the use of mixing of ultrasonic Lamb waves to characterize the tempering behaviour in metallic plate. Lamb wave mixing has been used to measure the generated second harmonic during tempering of mod.9Cr-1Mo steel plate. As-received material is normalized at 1080°C and then tempered in the temperature range of 600 - 850°C with a step size of 50°C for 1.5hrs and followed by furnace cooling. Lamb wave mixing technique has been used to assess the tempering behaviour of this material. Nonlinear ultrasonic parameter β which is the ratio of 2nd harmonic amplitude to the multiplication of the fundamental amplitudes is determined from the mixing wave at each temperature and correlated with microstructural characteristics. It is seen that this nonlinear acoustic parameter (β) is sensitive towards coherency strain generated between precipitate and matrix during tempering