In-medium pseudoscalar D/BD/B mesons and charmonium decay width

Using QCD sum rules and chiral SU(3) model, we investigate the effect of temperature, density, strangeness fraction and isospin asymmetric parameter on the shift in masses and decay constants of the pseudoscalar $D$ and $B$ meson in hadronic medium, which consist of nucleons and hyperons. The in-medium properties of $D$ and $B$ mesons within QCD sum rule approach depend upon the quark and gluon condensates. In chiral SU(3) model, quark and gluon condensates are introduced through the explicit symmetry breaking term and the trace anomaly property of the QCD, respectively and are written in terms of scalar fields $\sigma$, $\zeta$, $\delta$ and $\chi$. Hence, through medium modification of $\sigma$, $\zeta$, $\delta$ and $\chi$ fields, we obtain the medium modified masses and decay constants of $D$ and $B$ mesons. As an application, using $^3 P_0$ model, we calculate the in-medium decay width of the higher charmonium states $\psi(3686)$, $\psi(3770)$ and $\chi(3556)$ to the $D \bar{D}$ pairs, considering the in-medium mass of $D$ mesons. These results may be important to understand the possible outcomes of high energy physics experiments, e.g., CBM and PANDA at GSI, Germany.Comment: 31 pages and 7 figure

Three Essays in Corporate Finance

This dissertation consists of three essays in corporate finance. The essays study the applications of information friction to various contexts in corporate finance. In the first essay, I study a board's decision to fire or retain a CEO when board members care about their reputation in the labor market for directors. These concerns give the board an incentive to overweight public information and penalize (reward) the CEO for bad (good) luck, leading to an increase in turnover-performance sensitivity. I test the empirical predictions of the model using promotions of existing directors as a proxy for an increase in their reputational concerns. I find turnover-performance sensitivity is greater when a director is promoted. Further, I find CEO retention after a director takes on a new role culminates in lower future firm performance. Overall, the results suggest directors' incentives due to reputational concerns result in inefficient firing decisions. In the second essay, I study the effect of a decrease in the analyst coverage on the covenants of a firm's debt contracts. The decrease in analyst coverage is caused by dismissal of redundant analysts after mergers of brokerage houses during 1984-2005. I find that the likelihood of inclusion of covenants and the number of covenants in debt contracts are greater for firms which had lower analyst coverage. These findings suggest that the creditors take measures to counteract the increase in the agency costs by increasing the restrictiveness of the contracts. In the third essay, that is joint work with Sugato Bhattacharyya, I model a firm run by a manager who invests in a technology with uncertain returns. The manager has incentives to learn about fundamentals from the stock price, as well as to acquire her own private information to make better investment decisions. However, such learning increases information asymmetry between the informed trader and the liquidity traders because the informed trader's private information now allows him to predict the manager's actions. The greater information asymmetry results in greater price impact and greater price volatility but does not affect the trading volume or price informativeness. Importantly, the greater information asymmetry that arises due to the manager acquiring private information (but not the asymmetry due to her learning from the stock price) results in greater expected profits to the informed trader. The model suggests that manager's learning increases the incentives of the informed trader to gather precise information.PHDBusiness AdministrationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145952/1/rahulchh_1.pd

Heavy vector and axial-vector DD mesons in hot magnetized asymmetric nuclear matter

We observed the impact of finite magnetic field on the in-medium mass and decay constant of isospin averaged vector $D^*(D^{*^+},D^{*^0})$ and axial-vector $D_1(D^+_1, D^0_1)$ mesons. The quark and gluon condensates of the nuclear medium at finite magnetic field, temperature, isospin asymmetry, and density have been obtained by the meson exchange scalar fields within the chiral SU(3) model. The medium attributes modify the scalar and vector density of nuclear medium and this variation reflects in the in-medium mass and decay constant of spin 1 $D$ mesons. We calculate these observables by comparing the Operator Product Expansion (OPE) and the phenomenological side in the QCD Sum Rules. In the results, we observed a positive mass shift for charged vector and axial-vector $D$ mesons with respect to magnetic field. For neutral vector (axial-vector) $D$ mesons we observed negative (positive) mass shift as a function of magnetic field. In the application part, we calculate the in-medium partial decay width of the process $D^*_s$(2715/2860) $\rightarrow$ $D^* K$ by using $^3P_0$ model. The in-medium effects are incorporated through the in-medium masses of $D^*$ and $K$ mesons.Comment: 36 Pages, 11 figure

Successful live birth after heterotopic ruptured cornual pregnancy with twin intrauterine gestation in an in vitro fertilization conception

Heterotopic pregnancies, especially in the cornual region which were a rarity till recent times, have become a more common occurrence due to increasing practice of assisted reproduction. Optimal management of such cases is imperative to manage the risk of hypotension and shock in case of rupture and to judiciously preserve the intrauterine pregnancy. Here we are reporting a case of IVF conception of twin intrauterine pregnancy with a cornual heterotopic pregnancy. Patient presented to the emergency department with features of acute abdomen, haemoperitoneum and shock. Ultrasound findings were suggestive of rupture of cornual heterotopic pregnancy, 1500 ml haemoperitoneum with live twin intrauterine gestation. Patient was resuscitated with iv fluids blood transfusion. Immediate laparotomy was done and cornual site repaired and covered with an omental patch while preserving the intrauterine gestations. Thereafter, pregnancy was carefully monitored with a high index of suspicion for rupture of site of cornual repair with advancing gestational age. Patient was readmitted at 24 weeks with pain abdomen and cornual site was found to be 4mm in thickness. She was managed conservatively till 27 weeks when she had preterm rupture of membranes and emergency LSCS was done. She delivered healthy twin male babies, 780 gmb and 795 gm respectively. This case demonstrates that cornual heterotopic pregnancy is a diagnosis which may be easily missed and can present as a life-threatening complication if it ruptures and significant intraperitoneal bleeding occurs. However, it is possible to successfully manage these cases with timely intervention, proper uterine reconstruction and monitoring of intrauterine gestation