Dark matter, extra-terrestrial gamma-rays and the MSSM: a viability study

We fit the $\gamma$-ray excess from the galactic centre (GC) in terms of parameters of the minimal supersymmetric standard model (MSSM). Consistency with other $\gamma$-ray observation, such as those from dwarf spheroidal galaxies, is also ensured, in addition to the constraints from direct dark matter search. Furthermore, we expect the contribution to the relic density from the MSSM dark mater candidate, namely, the lightest neutralino, should not go below the stipulated value; otherwise it will amount to going beyond the MSSM by including some additional dark matter source. After a detailed scan of the parameter space in terms of four representative types of particle spectra, we identify the ones that are best fit to the observed data. However, these two are somewhat unsatisfactory in terms of $\chi^2_{min}$ as well as $p$-values. In some case(s), the unacceptability of low-$\chi^2_{min}$ regions due to direct search constraint is responsible for this. In others, the observed shape of the $\gamma$-ray spectrum makes the fits unsatisfactory. The imposed lower limit on relic density, too, has a role to play all along. On the whole, the conclusion is that the MSSM is not a very satisfactory fit for the GC $\gamma$-ray compounded with other cosmological observations and direct search limits.Comment: 40 pages, 16 figures: figures corrected, typos corrected, matches with version published in JCA

Attrition in SMEs: The Cause

Human Resource managers are devising ways to retain talent next year that will see companies paying annual increments up to 30%. The average attrition in 2010 was 10% across Indian companies, a rate that may rise to 25% in 2011-12 with improved salaries (The Economic Times, Dec 24, 2010) The SMEs sector in India has certainly been a very prevalent are of employment in recent years but one of the biggest encounters it is facing is a remarkable rise in attrition rate. There could be some common attrition factor across industry but every organization need to know the reason for attrition. India's economy is showing a healthy progress, but employers enjoying the bang have a offhand side: that of restless staff seeking for a hotter career option leading to increasing attrition in Indian SMEs. Authors have tried to find out the reason for attrition in SMEs, what the factors that are leading to attrition in SMEs in India? A conceptual framework has been developed to understand the relation between the factors affecting attrition. Our findings suggested some crucial factors affecting attrition in SMEs. This paper may be help for entrepreneurs to dealt with attrition in the organizations. KEYWORDS: Attrition, SMEs, Entrepreneurship, Indian Economy, Indi

Heavy dark matter particle annihilation in dwarf spheroidal galaxies: radio signals at the SKA telescope

A weakly interacting dark matter candidate is very difficult to detect at high-energy colliders like the LHC, if its mass is close to, or higher than, a TeV. We argue that the pair-annihilation of such particles may give rise to $e^+ e^-$-pairs in dwarf spheroidal galaxies (dSph), which in turn can lead to radio synchrotron signals that are detectable at the upcoming square kilometre array (SKA) telescope within a fairly moderate observation time. We investigate in detail the underlying mechanisms that make this possible. Both particle physics issues and those pertaining to astrophysics, such as diffusion, electromagnetic energy loss and the effects of interstellar magnetic field, are examined with reference to their roles in generating radio flux. We first identify the detectability criteria in a model-independent manner. It is observed that fluxes may be detectable for scenarios that are consistent with all constraints available till date from $\gamma$-ray and cosmic-ray observations. Thereafter, using benchmarks based on popular scenarios involving physics beyond the standard model, we show that it should be possible to detect the radio flux from a dSph like Draco with 100 hours of observation at the SKA, for dark matter particle masses upto 4-8 TeV. The corresponding frequency distributions are also presented, where it is found that the frequency range 300 MHz - 50 GHz is especially useful for recording the annihilation signals of trans-TeV particles.Comment: 27 pages, 14 figure

Charged black holes in generalized dilaton-axion gravity

We study generic Einstein-Maxwell-Kalb-Ramond-dilaton actions, and derive conditions under which they give rise to static, spherically symmetric black hole solutions. We obtain new asymptotically flat and non-flat black hole solutions which are in general electrically and magnetically charged. They have positive definite and finite quasi-local masses. Existing non-rotating black hole solutions (including those appearing in low energy string theory) are recovered in special limits.Comment: Replaced with revised version, 33 pages, No figure

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe