Study of the doubly charmed tetraquark $T_{cc}^+$

An exotic narrow state in the D0D0π + mass spectrum just below the D∗+D0 mass threshold is studied using a data set corresponding to an integrated luminosity of 9 fb−1 acquired with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The state is consistent with the ground isoscalar T+ cc tetraquark with a quark content of ccud and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D∗+ mesons is confirmed by the D0π + mass distribution. The mass of the resonance and its coupling to the D∗D system are analysed. Resonance parameters including the pole position, scattering length, effective range and compositeness are measured to reveal important information about the nature of the T+ cc state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.

Great circle analysis of South American VGP-distributions suggests widespread Cretaceous remagnetizations: case study of the Itararé Group Rocks from Brazil

<p>South American Jurassic/Cretaceous rocks has been troubled by elongated virtual geomagnetic pole (VGP) distributions, while many discordant poles from the Carboniferous to the Triassic have also been recognized, rendering the South American apparent polar wonder path (APWP) problematic. </p><p>We have conducted a paleomagnetic study of the sedimentary Permo-Carboniferous Itararé Group rocks within the state of São Paulo, Brazil, including three intruding mafic sills that are attributed to Early Cretaceus magmatic activity. The site-mean VGP distributions obtained from the sedimentary rocks define elongations that include the VGPs of the mafic intrusions, and are interpreted as remagnetization paths toward the directions characteristic of the sills. These interpretations are supported by extensive rock-magnetic data that provide a viable mechanism for the secondary magnetizations. Careful analysis of the paleomagnetic data of the sedimentary rocks enables isolation of a primary VGP distribution that is consistent with the reference Carboniferous pole position.</p><p>Analysis of other Carboniferous to Triassic South American paleomagnetic VGPs reveals that the majority of these data are also elongated: regardless of the age of the rocks, the elongations dominantly intersect at the location of the Late Cretaceous reference pole, and a second location similar to the intersection of the VGP elongations of some Jurassic/Cretaceous rock formations, and also coincides with the cusp of the debated loop in the Carboniferous-Triassic APWP. Based on multiple lines of evidence, we interpret the elongations and their intersections to reflect remagnetizations that occurred as a result of the widespread magmatism associated with the opening of the South Atlantic. We suggest that the extent of the remagnetizations is formation-specific, and that other rock-formations should be carefully re-evaluated.</p>

The influence of Antarctic and Greenland ice loss on polar motion: an assessment based on GRACE and multi-mission satellite altimetry

<p>Increasing ice loss of the Antarctic and Greenland Ice Sheets (AIS, GrIS) due to global climate change affects the orientation of the Earth’s spin axis with respect to an Earth-fixed reference system (polar motion). Ice mass changes in Antarctica and Greenland are observed by the Gravity Recovery and Climate Experiment (GRACE) in terms of time variable gravity field changes and derived from surface elevation changes measured by satellite radar and laser altimeter missions such as ENVISAT, CryoSat-2 and ICESat. Beside the limited spatial resolution, the accuracy of GRACE ice mass change estimates is limited by signal noise (meridional error stripes), leakage effects and uncertainties of the glacial isostatic adjustment (GIA) models, whereas the accuracy of satellite altimetry derived ice mass changes is limited by waveform retracking, slope related relocation errors, firn compaction and the density assumption used in the volume-to-mass conversion.</p><p> </p><p>In this study we use different GRACE gravity field models (CSR RL06M, JPL RL06M, ITSG-Grace2018) and satellite altimetry data (from TU Dresden, University of Leeds, Alfred Wegener Institute) to assess the accuracy of the gravimetry and altimetry derived polar motion excitation functions. We show that due to the combination of individual solutions, systematic and random errors of the data processing can be reduced and the robustness of the geodetic derived AIS and GrIS polar motion excitation functions can be increased. Based on these investigations we found that AIS mass changes induce the pole position vector to drift along the 60° East meridian by 2 mas/yr during the study period 2003-2015, whereas GrIS mass changes cause the pole vector to drift along the 45° West meridian by 3 mas/yr.</p>

Vodafone India Ltd: Managing in a Turbulent Emerging Market

Along with the global telecom sector, the Indian telecom market has evolved over the past three decades. From the first generation technology in the 1990s, the telecom industry in India offered 4G services in 2012. From microwave technology it has moved into underground fibre optic cables, enhancing the quality and variety of telecom services. Ahead of several emerging markets, subscriber demand in India shifted to data from voice telephony. Subscriber base grew substantially, but average revenue per user (ARPU) has fallen significantly. Intense competition has led to consolidation in the industry. The mobile services faced market disruption from Reliance Jio (R-Jio). The latter launched a strategy of predatory pricing resulting in data wars. R-Jio’s network was based on 4G technology, while other competitors were still offering 2G- and 3G-based services. In comparison to competitors, R-Jio laid more fibre optic cables. Therefore, it could effortlessly upgrade the services offerings to 5G and other future technologies, which competitors could not match so they experienced fall in profits or outright losses. R-Jio also moved into providing fibre-to-the-home technology accompanied with ultra-high-speed internet that could provide a host of entertainment features. As a virtual knee-jerk reaction to the severity of the competitive challenge facing it, Vodafone initiated merger talks with Idea Cellular and soon achieved its culmination. This merger resulted in the largest telecom service company in India. However, Vodafone Idea Ltd.’s balance sheet was over leveraged, rendering it incapable of playing the price cutting game. Besides, it was unclear if it would be able to build the formidable infrastructure required to invest in 5G spectrum, offer superior content as well as smart devices. It soon became obvious that the merger could catapult Vodafone to the pole position in the industry but staying and flourishing there would require it to be more resourceful, imaginative and aggressive. Balesh Sharma, the CEO of Vodafone-Idea Ltd., and his top management team had to respond to the challenges the company was facing and emerge successful.