Proton-proton physics in ALICE

The ALICE experiment has several unique features which makes it an important contributor to proton-proton physics at the LHC, in addition to its specific design goal of studying the physics of strongly interacting matter in heavy-ion collisions. The unique capabilities include its low transverse momentum (\pT) acceptance, excellent vertexing, particle identification over a broad \pT range and jet reconstruction. In this report, a brief review of ALICE capabilities is given for studying bulk properties of produced particles which characterize the underlying events, and the physics of heavy-flavour, quarkonia, photons, di-leptons and jets

Photons from Nucleus-Nucleus Collisions at Ultra-Relativistic Energies

We compare the photon emission rates from hot hadronic matter with in-medium mass shift and Quark Gluon Plasma (QGP). It is observed that the WA98 data can be well reproduced by hadronic initial state with initial temperature $\sim 200$ MeV if the universal scaling of temperature dependent hadronic masses are assumed and the evolution of temperature with time is taken from transport model or (3+1) dimensional hydrodynamics. The data can also be reproduced by QGP initial state with similar initial temperature and non-zero initial radial velocity.Comment: Talk given in the International Nuclear Physics Conference, at the University of California, Berkeley, USA, during July 30 - August 3, 200

Schwinger Mechanism for Gluon Pair Production in the Presence of Arbitrary Time Dependent Chromo-Electric Field

We study Schwinger mechanism for gluon pair production in the presence of arbitrary time-dependent chromo-electric background field $E^a(t)$ with arbitrary color index $a$=1,2,...8 in SU(3) by directly evaluating the path integral. We obtain an exact expression for the probability of non-perturbative gluon pair production per unit time per unit volume and per unit transverse momentum $\frac{dW}{d^4x d^2p_T}$ from arbitrary $E^a(t)$. We show that the tadpole (or single gluon) effective action does not contribute to the non-perturbative gluon pair production rate $\frac{dW}{d^4x d^2p_T}$. We find that the exact result for non-perturbative gluon pair production is independent of all the time derivatives $\frac{d^nE^a(t)}{dt^n}$ where $n=1,2,....\infty$ and has the same functional dependence on two casimir invariants $[E^a(t)E^a(t)]$ and $[d_{abc}E^a(t)E^b(t)E^c(t)]^2$ as the constant chromo-electric field $E^a$ result with the replacement: $E^a \to E^a(t)$. This result may be relevant to study the production of a non-perturbative quark-gluon plasma at RHIC and LHC.Comment: 13 pages latex, Published in European Physical Journal

Efficient fiber-optical interface for nanophotonic devices

We demonstrate a method for efficient coupling of guided light from a single mode optical fiber to nanophotonic devices. Our approach makes use of single-sided conical tapered optical fibers that are evanescently coupled over the last ~10 um to a nanophotonic waveguide. By means of adiabatic mode transfer using a properly chosen taper, single-mode fiber-waveguide coupling efficiencies as high as 97(1)% are achieved. Efficient coupling is obtained for a wide range of device geometries which are either singly-clamped on a chip or attached to the fiber, demonstrating a promising approach for integrated nanophotonic circuits, quantum optical and nanoscale sensing applications.Comment: 7 pages, 4 figures, includes supplementary informatio

Antidepressant activity of Trigonella foenum leaves in Wistar albino rats

Background: To evaluate antidepressant activity of ethanolic extract of Trigonella foenum in animal models.Methods: A total of 60 healthy male Wistar albino rats weighing 220-250 grams were used and they were divided into 10 groups of 6 rats in each. First five groups (1st -5th) were evaluated by Forced Swim Test (FST) and remaining by Tail Suspension Test (TST). 1st group (control) received normal saline 10 mg/kg, 2nd group (standard) Imipramine 10 mg/kg and 3rd, 4th and 5th groups (test) respectively received Trigonella foenum leaf ethanolic extract [TFEE] in different doses 100 mg, 200 mg, and 400 mg/kg per orally for 14 days. They were evaluated for antidepressant activity using FST after 60 minutes of drug administration on 14th day. Similarly, remaining five groups (6th to 10th) received the same drugs and evaluated using TST after 60 minutes of drug administration. Duration of immobility was noted for six minutes for each rat.Results: One way ANOVA and Tukey Krammer test were used for statistical analysis. The immobility periods were expressed in mean±SD. The immobility period in FST were 207.16±28.7, 50.08±2.9, 46.14±1.2, 40.5±3.4 and 40.0±3.6 seconds respectively for control, standard and three test groups of TFEE (100/200/400 mg/kg). Similarly, immobility periods of 163.11±31.9, 125.03±11.2, 138.81±16.44, 138.16±12.65, 127.58±4.3 seconds were noted for TST for remaining six groups. It was found that TFEE possess statistically significant (p<0.05) antidepressant activity, as evidenced by decrease in the immobility time in both the tests when compared to control group.Conclusions: Present study results demonstrated that TFEE possess antidepressant property in experimental models of depression

Production and Equilibration of the Quark-Gluon Plasma with Chromoelectric Field and Minijets

Production and equilibration of quark-gluon plasma are studied within the color flux-tube model, at the RHIC and LHC energies. Non-Abelian relativistic transport equations for quarks, antiquarks and gluons, are solved in the extended phase space which includes coordinates, momenta and color. Before the chromoelectric field is formed, hard and semihard partons are produced via minijets which provide the initial conditions necessary to solve the transport equations. The model predicts that in spite of the vast difference between the RHIC and LHC incident energies, once the local equilibrium is reached, the energy densities, the number densities and the temperatures at the two machines may not be very different from each other. The minijet input significantly alters the evolution of the deconfined matter, unless the color field is too strong. For the input parameters used here the equilibration time is estimated to be $\sim 1$ fm at RHIC and $\sim 0.5$ fm at LHC, measured from the instant when the two colliding nuclei have just passed through each other. The temperature at equilibration is found to be $\sim 250$ MeV at RHIC and $\sim 300$ MeV at LHC.Comment: version to appear in Phys. Rev. C; discussion enlarged to include comparison with other models; conclusions unchanged; 14 single-spaced pages + 8 ps figure