119299327
A Dual Beam H-alpha Doppler System to Acquire, Analyse and Anticipate Solar Eruptive Events Directed towards Earth
A new instrument with a dual-beam H-alpha Doppler system is being developed at the Udaipur Solar Observatory (USO) in order to improve the quality and quantity of data on quiet, activated and erupting filaments and prominences on the Sun, especially those associated with geo-effective coronal mass ejections. These data can be potentially used to construct three-dimensional topology of erupting filaments as they leave the surface of the Sun and can be compared with multi-wavelength data obtained from space missions such as STEREO, SOHO, and Hinode. The characterization of various optical components for the instrument is being carried out, and some preliminary results are described in the paper.
14528390
Distinguishing the Littlest Higgs model with T-parity from supersymmetry at the LHC using trileptons
Abstract We analyse hadronically quiet trilepton signatures in the T-parity conserving Littlest Higgs model and in R-parity conserving supersymmetry at the Large Hadron Collider. We identify the regions of the parameter space where such signals can reveal the presence of these new physics models above the Standard Model background and distinguish them from each other, even in a situation when the mass spectrum of the Littlest Higgs model resembles the supersymmetric pattern.
119275846
Distinguishing between SUSY and Littlest Higgs Model using trileptons at the LHC
Littlest Higgs model with T‐parity and Minimal Supersymmtric standard Model (MSSM) with R‐parity both give similar signatures in collider experiment with a huge amount of missing energy depending upon mass of the lightest T‐odd/R‐odd particle. In this talk, I will discuss possibility of distinguishing the two models at the LHC in hadronically quiet signal where masses of R‐odd particles are identical to masses of T‐odd particles.
119107758
Peccei-Quinn violating minimal supergravity and a 126 GeV Higgs boson
In a Peccei-Quinn extension of supergravity the h --> \gamma\gamma detection rate can be significantly enhanced due to the reduction of the total Higgs decay width. To assess the viability of various Peccei-Quinn extensions of minimal supergravity we perform a Bayesian analysis on three such scenarios. The main constraints on these models come from the currently observed Higgs boson like state by the Large Hadron Collider and from the WMAP observation of dark matter abundance. Our comparative study reveals that under these constraints the PQ violating scenarios with axino dark matter are clearly preferred over the minimal supegravity model with the lightest neutralino as a dark matter candidate.
119304022
Detecting fourth generation quarks at hadron colliders
A bstractAlthough there is no compelling evidence, at present, against the Standard Model (SM), in the past few years, a number of 2-3 sigma tensions have appeared which could be alleviated simply by adding another generation of fermions. Furthermore, a fourth generation could help resolve the issue of baryogenesis and the understanding of the hierarchy problem.In this paper, we consider the phenomenology of the fourth generation heavy quarks which would be pair produced at the LHC. We show that if such a quark with a mass in the phenomenologically interesting range of 400 GeV-600 GeV decays to a light quark and a W-boson, it will produce a signal in a number of channels which can be seen above the background from the three generation Standard Model processes. In particular, such quarks could be seen in channels where multiple jets are present with large missing momentum and either a single hard lepton, an opposite sign hard lepton pair or a same sign lepton pair.In the same sign dilepton channel there is little background and so an excess of such pairs at large invariant mass will indicate the presence of heavy down type quarks. More generally, in our study, the main tool we use to determine the mass of the heavy quark in each of the channels we consider is to use the kinematics of the decay of such quarks to resolve the momenta of the unobserved neutrinos. We show how this can be carried out, even in cases where the kinematics is under-determined by use of the approximation, which holds quite well, that the two heavy quarks are nearly at rest in the center of mass frame.Since it is very likely that at least the lightest heavy quark decays in the mode we consider, this means that it should be observed at the LHC. Indeed, it is expected that the mass splitting between the quarks is less than mW so that if the Cabbibo-Kobayshi-Maskawa (CKM) matrix element between the fourth and lower generations are not too small, both members of the fourth generation quark doublet will decay in this way. If this is so, the combined signal of these two quarks will make the signal for the fourth generation somewhat more prominent.
119201920
Probing Randall-Sundram Model using triphotons at the LHC
We investigate triphoton signals of the Randall-Sundram model at the Large Hadron Collider. Such a signal can be an important probe to the RS model as these are relatively cleaner from the hadronic activity and bear significant rate. The corresponding standard model background has also been studied in detail. We also show that a clear graviton reconstruction is possible in such signal.
10726039
A micron resolution optical scanner for characterization of silicon detectors.
The emergence of high position resolution (∼10 μm) silicon detectors in recent times have highlighted the urgent need for the development of new automated optical scanners of micron level resolution suited for characterizing microscopic features of these detectors. More specifically, for the newly developed silicon photo-multipliers (SiPM) that are compact, possessing excellent photon detection efficiency with gain comparable to photo-multiplier tube. In a short time, since their invention the SiPMs are already being widely used in several high-energy physics and astrophysics experiments as the photon readout element. The SiPM is a high quantum efficiency, multi-pixel photon counting detector with fast timing and high gain. The presence of a wide variety of photo sensitive silicon detectors with high spatial resolution requires their performance evaluation to be carried out by photon beams of very compact spot size. We have designed a high resolution optical scanner that provides a monochromatic focused beam on a target plane. The transverse size of the beam was measured by the knife-edge method to be 1.7 μm at 1 - σ level. Since the beam size was an order of magnitude smaller than the typical feature size of silicon detectors, this optical scanner can be used for selective excitation of these detectors. The design and operational details of the optical scanner, high precision programmed movement of target plane (0.1 μm) integrated with general purpose data acquisition system developed for recording static and transient response photo sensitive silicon detector are reported in this paper. Entire functionality of scanner is validated by using it for selective excitation of individual pixels in a SiPM and identifying response of active and dead regions within SiPM. Results from these studies are presented in this paper.
118095587
Does the QCD plasma contain gluons
A comparison of two appropriately chosen screening masses of color singlet operators in the pure glue QCD plasma indicates that at sufficiently high temperature it contains a weakly interacting massive quasiparticle with the quantum numbers of the electric gluon. Still in the deconfined phase, but closer to T c , the same mass ratio is similar to that at zero temperature, indicating that the propagating modes are more glueball-like, albeit with a lower scale for the masses. We observe a continuity between these two regimes.
118748492
phi-Meson Mass Modification in Heavy-Ion Collisions
We recently presented a method of analyzing invariant-mass spectra of kaon pairs resulting from decay of $\phi$ mesons produced in high-energy heavy-ion collisions. It can be used to extract the shifts in the mass and the width ($\Delta M$ and $\Delta \Gamma$) of the $\phi$ mesons when they are inside the dense matter formed in these collisions. We have now performed a Monte-Carlo simulation of this process. We illustrate our method with the help of available preliminary data. Extracted value of $\Delta M$ is significantly larger than that obtained with an earlier method. Our results are consistent with the experimentally observed $p_T$ dependence of the mass shift.
122594393
Minijets and associated production of photons and muons in high energy heavy ion collisions
Due to the large hadronic multiplicities involved in heavy ion collisions at LHC energies, production of photons and muons inside jets cannot be distinguished from production in isolation. Associated production rates for photons and muons in minijets are estimated. It is found that the muon cross section per uranium-uranium collision could be substantial.
118904356
Multiplicity distributions of intermediate mass fragments in the thermodynamic model
Multiplicity distributions of intermediate mass fragments (IMFs) seen in intermediate energy heavy ion collisions have been of great interest in the last ten years. The distributions of single intermediate sized elements are close to Poissonian and have been subjected to widely different physical interpretations. We calculate the multiplicity distributions in a thermodynamic model whose physical basis is equal populations in phase space, which implies equilibrium statistics. We found distributions of a single element are to a good approximation Poissonian, and this result is attributed to the small emission probability of a given IMF among all the possible channels. We also found significant deviation from a Poisson distribution for a range of IMFs, and suggest strong correlations as an explanation. The systematics of the multiplicity distributions are explored in both one-component and two-component models. In the one-component model, sudden changes for the multiplicity distributions are found at the phase transition region. In the two-component model, the multiplicity distributions have more subtleties. Results from the current model are compared with available data, and good agreements are found. New signals for the multiparticle correlations are also suggested.