Welcome to CHEP seminars

Recent Seminars at the Centre for High Energy Physics are listed on this webpage. You can also browse through older slides from this link here.
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RECENT SEMINARS

16.07.2012

4.00 pm

Lec. Hall - 3
Physical Science
Building
Double Parton Scattering
Speaker:  Aneesh Manohar
Affiliation:  University of California, San Diego, USA
Abstract :
Double parton scattering has been observed at the LHC, and is a significant background to Higgs and same sign WW production.The talk will describe the QCD analysis of double parton scattering, including double parton distributions and their Q^2 evolution. Double parton scattering allows one to measure quark spin and color correlations in the proton.

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slides of lecture
10.04.2012

3.00 pm

Lec. Hall - 3
Physical Science
Building
Drag force from AdS/CFT
Affiliation:  IOP, Bhubaneswar
Abstract :
Within the finite temperature N = 4 strongly coupled super Yang-Mills, we compute the dissipative force on an external quark in the presence of evenly distributed heavy quark cloud. This is computed holographically by constructing the corresponding gravity dual. We study the behaviour of this force as a function of the cloud density. Along the way, we also analyze the stability of the gravity dual for vector and tensor perturbations.

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slides of lecture
26.03.2012

4.00 pm

Lec. Hall - 3
Physical Science
Building
A new RG-summation method for extraction of $\alpha_s$ from hadronic $\tau$-decays
Speaker:  Gauhar Abbas
Affiliation:  Center for High Energy Physics, IISc
Abstract :
After reviewing the the QCD analysis of hadronic $\tau$ decays, we provide present phenomenological status. Then we introduce a new formalism based on renormalization group summation of the Adler function and extract the strong coupling at mass of the $\tau$ lepton by exploiting renormalization group improved perturbation series. We call this formalism 'improved fixed order perturbation theory'. We also study the analytical properties of the Adler function in this formalism and compare with other standard approaches. We show how the renormalon singularities affect the large order behaviour in our analysis and finally give the extracted value of $\alpha_s (m_\tau)$ which is practically coincides with recent lattice determination.

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slides of lecture
21.03.2012

3.00 pm

Lec. Hall - 3
Physical Science
Building
Higher spin fields in the BTZ black hole.
Speaker:  Shouvik Dutta
Affiliation:  Center for High Energy Physics, IISc
Abstract :
We solve the wave equations for arbitrary integer and half-integer spin fields in the BTZ black hole background and obtain exact expressions for their quasinormal modes. These quasinormal modes are shown to agree precisely with the poles of the corresponding two point function in the dual conformal field theory as predicted by the AdS/CFT correspondence. We also obtain an expression for the 1-loop determinant in terms of the quasinormal modes and show it agrees with that obtained by integrating the heat kernel found by group theoretic methods.

References: arXiv:1112.4619 , arXiv:1202.5831 .
08.03.2012

4.00 pm

Lec. Hall - 3
Physical Science
Building
Thermoelectric probe for neutral edge modes in the fractional quantum Hall regime
Speaker:  Dr. Sourin Das
Affiliation:  University of Delhi
Abstract :
The \nu = 5/2 anti-Pfaffian state and the \nu = 2/3 Abelian state are believed to have an edge state composed of counter-propagating charge and neutral edge modes. This situation allows the generation of a pure thermal bias between two composite edge states across a quantum point contact (QPC) as was experimentally established in Nature 466, 585 (2010). We show that replacing the QPC by a quantum dot provides a natural way for detecting the neutral modes via the finite current generated by the thermoelectric response of the dot. We also show that the degeneracies of the dot spectrum, dictated by the conformal field theories (CFTs) describing these states, induce asymmetries in the thermoelectric current peaks. This in turn provides a direct fingerprint of the corresponding CFT manifested in a different shape of peaks patterns for the two quantum Hall states.

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slides of lecture
07.03.2012

4.00 pm

Lec. Hall - 3
Physical Science
Building
High transverse momentum quarkonium production and dissociation in heavy ion collisions.
Speaker:  Rishi Sharma
Affiliation: Fermi National Laboratory, Illinois.
Abstract:
Melting of heavy quarkonium states like the J/\psi and the Upsilon mesons due to color screening in a deconfined quark-gluon plasma (QGP) has been proposed as one of the principal signatures for its formation. An expected experimental consequence of this melting  in the thermal medium created in heavy-ion collisions (HIC) is a suppression of the yield of heavy mesons, when compared to their yield in nucleon-nucleon (NN) collisions scaled with the number of binary interactions.  I will describe a calculation of the yields of quarkonia in heavy ion collisions at RHIC and the LHC as a function of the transverse momentum based upon heavy quark effective theory. Included is a consistent implementation of dynamically calculated nuclear matter effects, such as coherent power corrections, cold nuclear matter energy loss, and the Cronin effect in the initial state and collisional dissociation of quarkonia in the final state as they traverse through the QGP. I will compare the results with data where applicable. The large suppression of prompt J/\psi  in nucleus-nucleus collisions at the LHC might indicate for the first time a possible thermal modification of the quarkonium wavefunction at large transverse momentum.

slides of lecture

Our news
Mon,3 p.m
BSM
Beyond Standard Model Meeting. Every Monday, 3 p.m. Meeting Room.
Wed,3 p.m
MPM
Mathematical Physics Meeting. Every Wednesday, 3 p.m. Lecture Hall III.
06.03.12
Lectures on Helicity Amplitudes
Prof. S. Rindani's Lectures 3 and 4 on 14th and 16th of March