arXiv subjects

Natasha Sharma

Publications and source records attributed to Natasha Sharma.

22 records · Page 2Linked to original sources

arXiv2016

Disappearance of the Mach Cone in heavy ion collisions

We present an analysis of di-hadron correlations using recently developed methods for background subtraction which allow for higher precision measurements with fewer assumptions about the background. These studies indicate that low momentum jets interacting with the medium do not equilibrate with the medium, but rather that interactions with the medium lead to more subtle increases in their widths and fragmentation functions, consistent with observations from studies of higher momentum fully reconstructed jets. The away-side shape is not consistent with a Mach cone.

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arXiv2016

Background subtraction methods for precision measurements of di-hadron and jet-hadron correlations in heavy ion collisions

Di-hadron correlations and jet-hadron correlations are frequently used to study interactions of the Quark Gluon Plasma with the hard partons that form jets. The existing background subtraction methods for these studies depend on several assumptions and independent measurements of the Fourier coefficients of the combinatorial background. In this paper, we present two background subtraction methods which use the observation that the near-side correlation signal is negligible for large separations between the associated particle and the trigger. The combinatorial background is fit in this background-dominated region. Including the reaction plane dependence of the raw correlation improves these results. To test the accuracy of these methods, a simple model is used to simulate di-hadron and jet-hadron correlations with a combinatorial background similar to that observed in the data. The true signal is compared to the extracted signal. The results are compared to results from two variants of the Zero-Yield-At-Minimum (ZYAM) method. We test these methods for mid-peripheral and central collisions and for di-hadron and jet-hadron correlations. These methods are more precise than the ZYAM method with fewer assumptions about the shape and level of the combinatorial background, even in central collisions where the experimental resolution on the measurement of the reaction plane dependence is poor. These methods will allow more accurate studies of modifications of the away-side jet and will be particularly useful for studies of jet-hadron correlations, where the combinatorial background is poorly constrained from previous studies.

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arXiv2016

Results from (anti-)(hyper-)nuclei production and searches for exotic bound states with ALICE at the LHC

The excellent particle identification capabilities of the ALICE detector, using the time projection chamber and the time-of-flight detector, allow the detection of light nuclei and anti-nuclei. Furthermore, the high tracking resolution provided by the inner tracking system enables the separation of primary nuclei from those coming from the decay of heavier systems. This allows for the reconstruction of decays such as the hypertriton mesonic weak decay ($^3_Λ$H$\rightarrow ^3$He + $π^-$), the decay of a hypothetical bound state of a $Λ$n into a deuteron and pion or the H-dibaryon decaying into a $Λ$, a proton and a $π^{-}$. An overview of the production of stable nuclei and anti-nuclei in proton-proton, proton-lead and, in particular, lead-lead collisions is presented. Hypernuclei production rates in Pb--Pb are also shown, together with the upper limits estimated on the production of hypothetical exotica candidates. The results are compared with predictions for the production in thermal (statistical) and coalescence models.

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arXiv2009

Investigation of high p$_{t}$ events in Nucleus-Nucleus collisions using the Hijing event generator

In recent years lot of interest has been observed in the nucleus-nucleus collisions at RHIC energies in phenomena related to high $p_{t}$ physics \cite{ref1}. The suppression of high $p_{t}$ particles and disappearance of back-to-back jets compared to the scaling with number of binary nucleon-nucleon collisions indicates that a nearly perfect liquid is produced in these collisions. Results on self shadowing of high $p_{t}$ events are presented using hadron multiplicity associated to high $p_{t}$ and unbiased events in nucleus-nucleus collisions \cite{ref2} obtained from the hijing event generator.

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