15695031
Opto-Electronics in Large Array Gas Detector Systems
Large array gas detector systems are used in particle and nuclear physics experiments involving high-energy nucleon-nucleon and heavy-ion collisions. We have observed that in large array gas detector systems the momentary discharges inside the detector cells result in slowdown of High Voltage conditioning and possible hindrances in signal processing. We have explored the opto-electronic devices like the opto-coupler, optical fibre and signal processing circuit, which provide successful monitoring procedures and preventive measures to overcome the challenges produced in such complex detector systems.
118199078
Upsilon production in STAR
119230769
Performance and First Physics Results of the ALICE Muon Spectrometer
Abstract A precise measurement of the heavy-flavor production cross-sections in pp collisions is an essential baseline for the heavy-ion program. In addition it is a crucial test of pQCD models in the new energy regime at LHC. ALICE measures the muons from the decay of charmonium resonances and from the semileptonic decay of heavy-flavored hadrons in its forward ( − 4.0 η − 2.5 ) Muon Spectrometer. We discuss the status of the detector and present results of data taken in pp collisions at s = 7 TeV .
118429720
Quarkonia production at forward rapidities with the ALICE Experiment
Muons from the decay of charmonium resonances are detected in the ALICE Experiment at the Large Hadron Collider(LHC) for pp and Pb-Pb collisions with a muon spectrometer, covering the forward rapidity region 2.5$<$ $y$ $<$4.0. Analysis of the nuclear modification factor ($R_{\rm AA}$) at forward rapidity are presented and compared with mid-rapidity results from electrons in the central barrel covering $|y|<$0.9. The roles of suppression and regeneration mechanisms are discussed, as well as the importance of the results of the forthcoming p-Pb data taking for the estimate of cold nuclear matter effects on quarkonia. Perspectives for the bottomonia measurements are also given. Quarkonia results via muon channel from CMS experiment at LHC are compared with ALICE quarkonia measurements.
119222365
Study of resonance states of 11Be with isospectral bound state microscopic potential
The theoretical procedure of supersymmetric quantum mechanics (SQM) is adopted for the first time to study quasi-bound states of a weakly bound nuclear system using microscopic potential. The density dependent M3Y (DDM3Y) effective interaction was found earlier to give a satisfactory description of radioactivity, nuclear matter and scattering. In the present work, we have microscopically generated a two-body potential in a single folding model using the DDM3Y effective interaction. From this potential, SQM generated a family of isospectral potentials for 11Be (10Be + n). We investigated the 5/2+, 3/2− and 3/2+ resonance states of 11Be. The experimental data and the present calculations of excitation energies of the above resonance states are found to be in good agreement.
122669506
High voltage characteristic of large area cathode pad chambers for muon spectrometer of ALICE
AbstractLarge area Cathode Pad Chambers (CPC) with inner and outer radii of 23.7 cm and 117 cm respectively have been fabricated and tested for 2nd Tracking station of Muon Spectrometer of ALICE.The active area of this detector has a radiation length of less than 2 % and the frames are fabricated with Peek GF-30. The anode wire plane consists of 474 anode wires of which 53 % have lengths greater than 1 meter. The separation between the wire plane and the grounded cathode plane is 2.5 mm. The high voltage behaviour of the chamber have been tested under two situations.
With no support below the wires to reduce sagging of long wires.With a G10 strip-support whose dimension is 950 mm × 2 mm × 2.4 mm.
 The High Voltage (HV) tests show that a better stability is achieved when the strip support is implemented. Therefore this solution has been adopted for operation in ALICE.
121418091
Quantum fluctuations near a black-hole singularity
Abstract We present here an investigation of the problem of quantum fluctuations near a black-hole singularity. We show that quantum fluctuations do not vanish near the singularity leading to the conclusion that black-hole singularities are unlikely to exist.
118578316
Chaos around holographic Regge trajectories
A bstractUsing methods of Hamiltonian dynamical systems, we show analytically that a dynamical system connected to the classical spinning string solution holographically dual to the principal Regge trajectory is non-integrable. The Regge trajectories themselves form an integrable island in the total phase space of the dynamical system. Our argument applies to any gravity background dual to confining field theories and we verify it explicitly in various supergravity backgrounds: Klebanov-Strassler, Maldacena-Núñez, Witten QCD and the AdS soliton. Having established non-integrability for this general class of supergravity backgrounds, we show explicitly by direct computation of the Poincaré sections and the largest Lyapunov exponent, that such strings have chaotic motion.
119111711
Analysis of an extended scalar sector with S3 symmetry
We investigate the scalar potential of a general S3-symmetric three-Higgs-doublet model. The outcome of our analysis does not depend on the fermionic sector of the model. We identify a decoupling limit for the scalar spectrum of this scenario. In view of the recent LHC Higgs data, we show our numerical results only in the decoupling limit. Unitarity and stability of the scalar potential demand that many new scalars must be lurking below 1 TeV. We provide numerical predictions for h→γγ and h→Zγ signal strengths, which can be used to falsify the theory.
118393178
Geometric Entropy
The laws of mechanics of stationary black holes bear a close resemblance with the laws of thermodynamics. This is not only a mathematical analogy but also a physical one that helps us answer deep questions related to the thermodynamic properties of the black holes. It turns out that we can define an entropy which is purely geometrical for black holes. In this thesis we explain Wald’s formulation which identifies black hole entropy for an arbitrary covariant theory of gravity. We would like to know precisely what inputs go into arriving at Wald’s formalism. This expression for the entropy clearly depends on the precise form of the action. The secondary theme of this thesis is to distinguish thermodynamic laws which are kinematic from those which are dynamical. We would like to see explicitly in the derivation of these laws, where exactly the form of action plays a role. In the beginning we motivate the definition of entropy using the Einstein-Hilbert Lagrangian. We encounter the Zeroth law, the Hawking radiation, the second law, and then Wald’s formulation.
119230166
Nondecoupling of charged scalars in Higgs decay to two photons and symmetries of the scalar potential
A large class of two- and three-Higgs-doublet models with discrete symmetries has been employed in the literature to address various aspects of flavor physics. We analyze how the precision measurement of the Higgs to diphoton signal strength would severely constrain these scenarios due to the nondecoupling behavior of the charged scalars, to the extent that in the presence of exact discrete symmetry, the number of additional noninert scalar doublets can be constrained no matter how heavy the nonstandard scalars are. We demonstrate that if the scalar potential is endowed with appropriate global continuous symmetries together with soft breaking parameters, decoupling can be achieved thanks to the unitarity constraints on the mass-square differences of the heavy scalars.