CMBR Weak Lensing and HI 21-cm Cross-correlation Angular Power Spectrum

Weak gravitational lensing of the CMBR manifests as a secondary anisotropy in the temperature maps. The effect, quantified through the shear and convergence fields imprint the underlying large scale structure (LSS), geometry and evolution history of the Universe. It is hence perceived to be an important observational probe of cosmology. De-lensing the CMBR temperature maps is also crucial for detecting the gravitational wave generated B-modes. Future observations of redshifted 21-cm radiation from the cosmological neutral hydrogen (HI) distribution hold the potential of probing the LSS over a large redshift range. We have investigated the correlation between post-reionization HI signal and weak lensing convergence field. Assuming that the HI follows the dark matter distribution, the cross-correlation angular power spectrum at a multipole \ell is found to be proportional to the cold dark matter power spectrum evaluated at \ell/r, where r denotes the comoving distance to the redshift where the HI is located. The amplitude of the ross-correlation depends on quantities specific to the HI distribution, growth of perturbations and also the underlying cosmological model. In an ideal ituation, we found that a statistically significant detection of the cross-correlation signal is possible. If detected, the cross-correlation signal hold the possibility of a joint estimation of cosmological parameters and also test various CMBR de-lensing estimators.Comment: 14 pages, 4 figures, publishe

Searching for the light dark gauge boson in GeV-scale experiments

We study current constraints and search prospects for a GeV scale vector boson at a range of low energy experiments. It couples to the Standard Model charged particles with a strength <= 10^-3 to 10^-4 of that of the photon. The possibility of such a particle mediating dark matter self-interactions has received much attention recently. We consider searches at low energy high luminosity colliders, meson decays, and fixed target experiments. Based on available data, searches both at colliders and in meson decays can discover or exclude such a scenario if the coupling strength is on the larger side. We emphasize that a dedicated fixed target experiment has a much better potential in searching for such a gauge boson, and outline the desired properties of such an experiment. Two different optimal designs should be implemented to cover the range of coupling strength 10^-3 to 10^-5, and < 10^-5 of the photon, respectively. We also briefly comment on other possible ways of searching for such a gauge boson.Comment: 33 pages, 5 figures; v2: corrected discussion of Upsilon decays, updates to discussion of fixed-target experiments and QED constraints, numerous minor changes, references added; v3: typo corrected relative to the JHEP published versio

Possible role of bonding angle and orbital mixing in iron pnictide superconductivity: Comparative electronic structure studies of LiFeAs and Sr2VO3FeAs

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Efficacy and tolerability of trastuzumab emtansine in advanced human epidermal growth factor receptor 2–positive breast cancer

© 2018, Hong Kong Academy of Medicine Press. All rights reserved. Introduction: The management of human epidermal growth factor receptor 2 (HER2)–positive breast cancer has changed dramatically with the introduction and widespread use of HER2-targeted therapies. There is, however, relatively limited real-world information about the effectiveness and safety of trastuzumab emtansine (T-DM1) in Hong Kong Chinese patients. We assessed the efficacy and toxicity profiles among local patients with HER2-positive advanced breast cancer who had received T-DM1 therapy in the second-line setting and beyond. Methods: This retrospective study involved five local centres that provide service for over 80% of the breast cancer population in Hong Kong. The study period was from December 2013 to December 2015. Patients were included if they had recurrent or metastatic histologically confirmed HER2+ breast cancer who had progressed after at least one line of anti-HER2 therapy including trastuzumab. Patients were excluded if they received T-DM1 as first-line treatment for recurrent or metastatic HER2+ breast cancer. Patient charts including biochemical and haematological profiles were reviewed for background information, T-DM1 response, and toxicity data. Adverse events were documented during chemotherapy and 28 days after the last dose of medication. Results: Among 37 patients being included in this study, 28 (75.7%) had two or more lines of anti-HER2 agents and 26 (70.3%) had received two or more lines of palliative chemotherapy. Response assessment revealed that three (8.1%) patients had a complete response, eight (21.6%) a partial response, 11 (29.7%) a stable disease, and 12 (32.4%) a progressive disease; three patients could not be assessed. The median duration of response was 17.3 (95% confidence interval, 8.4-24.8) months. The clinical benefit rate (complete response + partial response + stable disease, ≥12 weeks) was 37.8% (95% confidence interval, 22.2%-53.5%). The median progression-free survival was 6.0 (95% confidence interval, 3.3-9.8) months and the median overall survival had not been reached by the data cut-off date. Grade 3 or 4 toxicities included thrombocytopaenia (13.5%), raised alanine transaminase (8.1%), anaemia (5.4%), and hypokalaemia (2.7%). No patient died as a result of toxicities. Conclusions: In patients with HER2-positive advanced breast cancer who have been heavily pretreated with anti-HER2 agents and cytotoxic chemotherapy, T-DM1 is well tolerated and provided a meaningful progression-free survival of 6 months and an overall survival that has not been reached. Further studies to identify appropriate patient subgroups are warranted.Link_to_subscribed_fulltex

The Discrepancy Between tau and e+e- Spectral Functions Revisited and the Consequences for the Muon Magnetic Anomaly

We revisit the procedure for comparing the pi pi spectral function measured in tau decays to that obtained in e+e- annihilation. We re-examine the isospin-breaking corrections using new experimental and theoretical input, and find improved agreement between the tau- --> pi- pi0 nu_tau branching fraction measurement and its prediction using the isospin-breaking-corrected e+e- --> pi+pi- spectral function, though not resolving all discrepancies. We recompute the lowest order hadronic contributions to the muon g-2 using e+e- and tau data with the new corrections, and find a reduced difference between the two evaluations. The new tau-based estimate of the muon magnetic anomaly is found to be 1.9 standard deviations lower than the direct measurement.Comment: 10 pages, 6 figures, submitted to Eur. Phys. J. C; (v2): Revised version with improved and uniform treatment of tau and e+e- data with HVPTools and a few minor bug fixes; (v3): Final version accepted for publicatio

Understanding Galaxy Formation and Evolution

The old dream of integrating into one the study of micro and macrocosmos is now a reality. Cosmology, astrophysics, and particle physics intersect in a scenario (but still not a theory) of cosmic structure formation and evolution called Lambda Cold Dark Matter (LCDM) model. This scenario emerged mainly to explain the origin of galaxies. In these lecture notes, I first present a review of the main galaxy properties, highlighting the questions that any theory of galaxy formation should explain. Then, the cosmological framework and the main aspects of primordial perturbation generation and evolution are pedagogically detached. Next, I focus on the ``dark side'' of galaxy formation, presenting a review on LCDM halo assembling and properties, and on the main candidates for non-baryonic dark matter. It is shown how the nature of elemental particles can influence on the features of galaxies and their systems. Finally, the complex processes of baryon dissipation inside the non-linearly evolving CDM halos, formation of disks and spheroids, and transformation of gas into stars are briefly described, remarking on the possibility of a few driving factors and parameters able to explain the main body of galaxy properties. A summary and a discussion of some of the issues and open problems of the LCDM paradigm are given in the final part of these notes.Comment: 50 pages, 10 low-resolution figures (for normal-resolution, DOWNLOAD THE PAPER (PDF, 1.9 Mb) FROM http://www.astroscu.unam.mx/~avila/avila.pdf). Lectures given at the IV Mexican School of Astrophysics, July 18-25, 2005 (submitted to the Editors on March 15, 2006

On the reliability of merger-trees and the mass growth histories of dark matter haloes

We have used merger trees realizations to study the formation of dark matter haloes. The construction of merger-trees is based on three different pictures about the formation of structures in the Universe. These pictures include: the spherical collapse (SC), the ellipsoidal collapse (EC) and the non-radial collapse (NR). The reliability of merger-trees has been examined comparing their predictions related to the distribution of the number of progenitors, as well as the distribution of formation times, with the predictions of analytical relations. The comparison yields a very satisfactory agreement. Subsequently, >.........Comment: A&SS Accepte

Heavy quarkonium: progress, puzzles, and opportunities

A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the $B$-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

On the spin distributions of Λ\LambdaCDM haloes

We used merger trees realizations, predicted by the extended Press-Schechter theory, in order to study the growth of angular momentum of dark matter haloes. Our results showed that: 1) The spin parameter $\lambda'$ resulting from the above method, is an increasing function of the present day mass of the halo. The mean value of $\lambda'$ varies from 0.0343 to 0.0484 for haloes with present day masses in the range of $10^9\mathrm{h}^{-1}M_{\odot}$ to $10^{14}\mathrm{h}^{-1}M_{\odot}$. 2)The distribution of $\lambda'$ is close to a log-normal, but, as it is already found in the results of N-body simulations, the match is not satisfactory at the tails of the distribution. A new analytical formula that approximates the results much more satisfactorily is presented. 3) The distribution of the values of $\lambda'$ depends only weakly on the redshift. 4) The spin parameter of an halo depends on the number of recent major mergers. Specifically the spin parameter is an increasing function of this number.Comment: 10 pages, 8 figure