Name: Advances in Astroparticle Physics and Cosmology (AAPCOS)
Start: 2015-10-12T09:00:00+05:30
End: 2015-10-17T18:00:00+05:30
Location: Saha Institute of Nuclear Physics

Advances in Astroparticle Physics and Cosmology (AAPCOS)

from Monday 12 October 2015 (09:00) to Saturday 17 October 2015 (18:00)

Monday 12 October 2015

09:00

09:00 - 09:45
Room: Meghnad Saha Auditorium

09:50

09:50 - 10:00
Room: Meghnad Saha Auditorium
10:00 Lecture 1: Dark Matter Detection-I - Victor Zacek
Lecture 1: Dark Matter Detection-I
- Victor Zacek
10:00 - 11:15
Room: Meghnad Saha Auditorium The quest for the mysterious missing mass of the Universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the Universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the Universe is of a new exotic kind, different from the "ordinary" matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world- wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called "direct detection" techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the "indirect detection" of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative non- particle searches and future prospects.
11:15 Tea
Tea
11:15 - 11:45
Room: Meghnad Saha Auditorium
11:45 Lecture 2: Low background technologies in underground physics-I - Ivan Stekl (Czech Technical University in Prague)
Lecture 2: Low background technologies in underground physics-I
- Ivan Stekl (Czech Technical University in Prague)
11:45 - 13:00
Room: Meghnad Saha Auditorium Over the past decades, fundamental physics experiments such as dark matter or double beta decay have required ultra-low background environments. Successful results from these experiments depend critically on selection of radiologically ultra-pure materials, high suppression of all types of radioactivity (cosmic rays, gamma rays, neutrons, radon and its progenies). In the presentation, I will summarize the deep underground laboratories in the world, the basic methods of selection of ultra-pure materials, shielding of different types of radioactivity as well as the suppression of radioactivity caused by the presence of radon. Influence of the background on statistical significance of the obtained results and the progressive detection methods (pixel detectors) allowing further suppression of the background will be also presented.
13:00 Lunch
Lunch
13:00 - 14:00
Room: Meghnad Saha Auditorium
14:00 Lecture 3: Dark Matter Theory-I - Paolo Gondolo (University of Utah)
Lecture 3: Dark Matter Theory-I
- Paolo Gondolo (University of Utah)
14:00 - 15:15
Room: Meghnad Saha Auditorium NA
15:15 Lecture 4: Low background technologies in underground physics-II - Ivan Stekl (Czech Technical University in Prague)
Lecture 4: Low background technologies in underground physics-II
- Ivan Stekl (Czech Technical University in Prague)
15:15 - 16:30
Room: Meghnad Saha Auditorium Over the past decades, fundamental physics experiments such as dark matter or double beta decay have required ultra-low background environments. Successful results from these experiments depend critically on selection of radiologically ultra-pure materials, high suppression of all types of radioactivity (cosmic rays, gamma rays, neutrons, radon and its progenies). In the presentation, I will summarize the deep underground laboratories in the world, the basic methods of selection of ultra-pure materials, shielding of different types of radioactivity as well as the suppression of radioactivity caused by the presence of radon. Influence of the background on statistical significance of the obtained results and the progressive detection methods (pixel detectors) allowing further suppression of the background will be also presented.
16:30 Tea
Tea
16:30 - 17:00
Room: Meghnad Saha Auditorium
17:00 Lecture 5: Dark Matter Detection-II - Viktor Zacek
Lecture 5: Dark Matter Detection-II
- Viktor Zacek
17:00 - 18:15
Room: Meghnad Saha Auditorium The quest for the mysterious missing mass of the Universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the Universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the Universe is of a new exotic kind, different from the "ordinary" matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world- wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called "direct detection" techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the "indirect detection" of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative non- particle searches and future prospects.
Tuesday 13 October 2015
10:00 Lecture 6: Dark Matter Theory-II - Paolo Gondolo (University of Utah)
Lecture 6: Dark Matter Theory-II
- Paolo Gondolo (University of Utah)
10:00 - 11:15
Room: Meghnad Saha Auditorium NA
11:15 Tea
Tea
11:15 - 11:45
Room: Meghnad Saha Auditorium
11:45 Lecture 7: Dark Matter Detection-III - Viktor Zacek
Lecture 7: Dark Matter Detection-III
- Viktor Zacek
11:45 - 13:00
Room: Meghnad Saha Auditorium The quest for the mysterious missing mass of the Universe has become one of the big challenges of today's particle physics and cosmology. Astronomical observations show that only 1% of the matter of the Universe is luminous. Moreover there is now convincing evidence that 85% of all gravitationally observable matter in the Universe is of a new exotic kind, different from the "ordinary" matter surrounding us. In a series of three lectures we discuss past, recent and future efforts made world- wide to detect and/or decipher the nature of Dark Matter. In Lecture I we review our present knowledge of the Dark Matter content of the Universe and how experimenters search for it's candidates; In Lecture II we discuss so-called "direct detection" techniques which allow to search for scattering of galactic dark matter particles with detectors in deep-underground laboratories; we discuss the interpretation of experimental results and the challenges posed by different backgrounds; In Lecture III we take a look at the "indirect detection" of the annihilation of dark matter candidates in astrophysical objects, such as our sun or the center of the Milky Way; In addition we will have a look at efforts to produce Dark Matter particles directly at accelerators and we shall close with a look at alternative non- particle searches and future prospects.
13:00

13:00 - 13:05
Room: Meghnad Saha Auditorium

13:05 Lunch
Lunch
13:05 - 14:00
Room: Meghnad Saha Auditorium
14:00
14:00 - 18:30
Room: Meghnad Saha Auditorium
Contributions

14:00 Collider to Cosmology- mini bang to the big bang - Bikash Sinha (VECC, Kolkata)

14:30 Neutrinos in Astrophysics and Cosmology - Palash Baran Pal (SINP, Kolkata)

15:15 Search for Dark Matter in the sky - Aldo Morselli (INFN)

16:15 ASTROSAT and beyond: Some science and technology prospects - Biswajit Paul (RRI, Bangalore)

17:00 Dark Energy of the Universe - Probir Roy (CAPSS, Bose Institute, Kolkata)

17:45 Square Kilometre Array: Exploring the Universe with the world's largest radio telescope - Tirthankar Roy Choudhury (NCRA-TIFR, Pune)
Wednesday 14 October 2015

09:00

09:00 - 09:30
Room: Meghnad Saha Auditorium

09:30

09:30 - 09:50
Room: Meghnad Saha Auditorium
09:50 Trends in Dark Matter Physics - Paolo Gondolo (University of Utah)
Trends in Dark Matter Physics
- Paolo Gondolo (University of Utah)
09:50 - 10:35
Room: Meghnad Saha Auditorium NA
10:35 Supernova Remnants: The Cosmic-ray Accelerators in the Milky Way - Tülün Ergin (TUBITAK UZAY)
Supernova Remnants: The Cosmic-ray Accelerators in the Milky Way
- Tülün Ergin (TUBITAK UZAY)
10:35 - 11:20
Room: Meghnad Saha Auditorium Based on the X5 and gamma-ray observations made in the last 30 years, supernova remnants (SNRs) and their strong shock waves, have been widely accepted as the production sites for cosmic rays (CRs) with energies up to 1015 eV. Theoretical models and observations indicate that the diffusive shock acceleration process can produce particles of the required energies and imply that magnetic fields are amplified in very strong collisionless shocks. In SNRs interacting with molecular clouds (MCs), the hadronic model, where a neutral pion produced by the interactions of two protons, decays into two gammas, is the dominating scenario. In young SNRs displaying bright non-thermal X-ray emission, the gamma-ray emission is consistent with the hadronic scenario as well as the leptonic scenario involving the relativistic electrons. In this talk, we would like to discuss about these scenarios of gamma-ray production for 3C 391 and G349.7+0.2, middle-aged mixed-morphology SNRs interacting with MCs, and for Cassiopeia A, a young shell-like SNR, in a multiwavelength frame.
11:20 Tea
Tea
11:20 - 11:50
Room: Meghnad Saha Auditorium
11:50 Cosmology in the Post Planck era - Tarun Souradeep (IUCAA, Pune)
Cosmology in the Post Planck era
- Tarun Souradeep (IUCAA, Pune)
11:50 - 12:35
Room: Meghnad Saha Auditorium The widely heralded, remarkable, progress in cosmology leading to the emergence of a 'standard cosmological model’ has relied on certain key assumptions at different levels. I describe work along multiple facets, largely, from the research program of my group at IUCAA over the past 15 years, that have all attempted to adopt an agnostic approach in drawing cosmological inference independent of such assumptions, in the context of the increasing exquisite observations of the Cosmic Microwave Background CMB anisotropy.
12:35 Dark Energy: An Observational Perspective - Ujjaini Alam (ISI, Kolkata)
Dark Energy: An Observational Perspective
- Ujjaini Alam (ISI, Kolkata)
12:35 - 13:00
Room: Meghnad Saha Auditorium Dark energy is one of the most tantalizing mysteries in current cosmological research. A host of observations confirm that about two-thirds of the energy content of the universe comprises this negative-pressure ``dark energy'' component that causes the expansion of the universe to accelerate. Though various theoretical models have been suggested for dark energy, the final conclusion on the nature of dark energy may well come from the observations. In this talk I shall outline the recent developments in observations which are expected to constrain dark energy parameters. I will also outline the potential future directions in dark energy observations.
13:00 Lunch
Lunch
13:00 - 14:00
Room: Meghnad Saha Auditorium
14:00 How well can gravitational wave observations of coalescing binaries involving neutron stars constrain the neutron star equation of state? - Sukanta Bose (IUCAA, Pune)
How well can gravitational wave observations of coalescing binaries involving neutron stars constrain the neutron star equation of state?
- Sukanta Bose (IUCAA, Pune)
14:00 - 14:45
Room: Meghnad Saha Auditorium The Advanced LIGO detectors began observation runs a few weeks ago. This has afforded relativists and astronomers the opportunity to use gravitational waves to improve our understanding of a variety of astronomical objects and phenomena. In this talk I will examine how well gravitational wave observations of coalescing binaries involving neutron stars might constrain the neutron star (NS) equation of state. These astrophysical constraints can improve our understanding of nuclear interactions in ways that complement the knowledge acquired from terrestrial labs. I will study the effects of different NS equations of states in both NS-NS and NS-Black Hole systems, with and without spin, on these constraints.
14:45 Neutrino Oscillation: past, present and future - Srubabati Goswami (Physical Research Laboratory)
Neutrino Oscillation: past, present and future
- Srubabati Goswami (Physical Research Laboratory)
14:45 - 15:30
Room: Meghnad Saha Auditorium NA
15:30 Tea
Tea
15:30 - 15:45
Room: Meghnad Saha Auditorium
15:45 Supermassive Black Holes and their Host Dark Matter Halos - Suchetana Chatterjee (Presidency University)
Supermassive Black Holes and their Host Dark Matter Halos
- Suchetana Chatterjee (Presidency University)
15:45 - 16:10
Room: Meghnad Saha Auditorium Through a plethora of observational results we now know that there is a supermassive black hole (SMBH) at the center of every galaxy in the Universe with a fraction of them harboring an active accretion disc and are known as active galactic nuclei (AGN). Thus in the paradigm of structure formation we like to address the question of relating SMBH with their host dark matter halos. Observationally by studying the spatial clustering of SMBH or AGN we can infer about their dark matter hosts. AGN clustering can be characterized within a powerful theoretical framework known as the Halo Occupation Distribution (HOD). In this talk ,I shall discuss about the HOD modeling of AGN using a fully cosmological simulation and show that the underlying theoretical model fits the two-point correlation function (2PCF) of different types of AGN. This provides us an evolutionary picture of AGN along with dark matter halos over cosmic time. In the later half of the talk I shall provide some limitations of the 2PCF fitting method and provide alternative ways to measure the HOD of AGN while trying to address some fundamental questions in AGN physics from a cosmological point-of-view.
16:10 Non-directional and directional detection of dark matter in universal bound states - Ranjan Laha (Stanford University)
Non-directional and directional detection of dark matter in universal bound states
- Ranjan Laha (Stanford University)
16:10 - 16:35
Room: Meghnad Saha Auditorium We study the signatures for internal structure of dark matter in direct detection directional and non-directional experiments in the context of asymmetric self-interacting dark matter. The self-interaction cross section of two dark matter particles at low energies is assumed to come close to saturating the S-wave unitarity bound, which requires the presence of a resonance near their scattering threshold. The universality of S-wave near-threshold resonances then implies that the low-energy scattering properties of a two-body bound state of dark matter particles are completely determined by its binding energy, irrespective of the underlying microphysics. The form factor for elastic scattering of the bound state from a nucleus and the possibility of breakup of the bound state produce new signatures in the nuclear recoil energy spectrum. Observations of these recoil structures will give a smoking gun signature of dark matter bound states.
16:35 Cosmology : Understanding Early and Late Universe - B. C. Paul (NBU, Siliguri)
Cosmology : Understanding Early and Late Universe
- B. C. Paul (NBU, Siliguri)
16:35 - 17:00
Room: Meghnad Saha Auditorium NA
17:00 Hints for a TeV scale $W_R$ at the LHC and constraints on leptogenesis - Chandan Hati (PRL, Ahmedabad)
Hints for a TeV scale $W_R$ at the LHC and constraints on leptogenesis
- Chandan Hati (PRL, Ahmedabad)
17:00 - 17:25
Room: Meghnad Saha Auditorium The discovery of a right-handed charged gauge boson $W_R^\pm$ with mass of around a few TeV, for example through a signal of two leptons and two jets that has been reported by CMS to have a 2.8$\sigma$ local excess or through a signal of a resonance decaying into a pair of Standard Model gauge bosons showing a local excess of 3.4$\sigma$ (2.5$\sigma$ global) reported by ATLAS search, can have severe implications for the leptogenesis mechanism, which offers a very attractive possibility to explain the baryon asymmetry of the universe. In this talk I shall discuss the constraints on the high scale as well as the TeV scale leptogenesis from lepton number violating scattering processes mediated via right-handed heavy neutrinos ($N_{R}$) and the right-handed doubly charged Higgs $\Delta^{++}_{R}$ which can rule out the possibility of successful leptogenesis for $W_{R}^{\pm}$ with mass in the TeV range. Complementing the above results, we shall also discuss the low-energy subgroups of superstring motivated $E_{6}$ model which can allow for high-scale leptogenesis, and explain the excess signal at the LHC reported by the CMS experiment from resonant slepton decay.
17:25
17:25 - 18:35
Room: Meghnad Saha Auditorium
Contributions

17:25 Gravity mediated Preheating - Debaprasad Maity (IIT Guwahati)

17:25 Thermodynamical Interpretation of Geometrical Variables Associated with Null Surfaces - Sumanta Chakraborty (IUCAA)

17:50 Bounds on IDM from the electroweak vacuum metastability - Najimuddin Khan (Indian Institute of Technology Indore)

17:50 Inflationary predictions and moduli masses - Kumar Das (Saha Institute Of Nuclear Physics)

18:05 Consequences of Pilgrim Dark Energy in $f(T, T_G)$ cosmology - Surajit Chattopadhyay (PCMT, Kolkata)

18:05 EVIDENCE FOR HIGH DENSITY EARLY UNIVERSE FROM ELEMENTARY PARTICLE PHYSICAL DATA - Girish T.E (Department of Physics ,UniversityCollege.Trivandrum 695034 India)

18:20 The Space-time of Dark-matter - Dipanjan Dey (IIT Kanpur)
Thursday 15 October 2015
09:00 A geometric approach to moduli stabilization in a higher curvature braneworld - Soumitra Sengupta (IACS, Kolkata)
A geometric approach to moduli stabilization in a higher curvature braneworld
- Soumitra Sengupta (IACS, Kolkata)
09:00 - 09:45
Room: Meghnad Saha Auditorium Higher curvature theories are subject of considerable interest in the study of gravitational theories beyond Einstein’s gravity. Braneworld models in presence of higher curvature bulk lead to many interesting features starting from inflationary cosmology to collider phenomenology due to the presence of moduli fields. In this context, stabilization of the moduli in different higher dimensional models is a must for a proper resolution to the gauge hierarchy problem in elementary particle Physics. Such stabilization is normally achieved by introducing an external bulk field (known as stabilizing field) with ad hoc bulk and boundary potential. In this work we demonstrate that such a stabilization can be achieved by a purely geometrodynamical way originating from the higher curvature quantum corrections in the gravity sector.
09:45 If There is Heaven on Earth - Biswarup Mukhopadhyaya (HRI, Allahabad)
If There is Heaven on Earth
- Biswarup Mukhopadhyaya (HRI, Allahabad)
09:45 - 10:30
Room: Meghnad Saha Auditorium We talk about some situations where less frequently discussed dark matter scenarios can substantially affect collider search strategies for new physics.
10:30 Probing the Universe with Cosmic Neutral Hydrogen - Tirthankar Roy Choudhury (NCRA-TIFR, Pune)
Probing the Universe with Cosmic Neutral Hydrogen
- Tirthankar Roy Choudhury (NCRA-TIFR, Pune)
10:30 - 10:55
Room: Meghnad Saha Auditorium As is well known, hydrogen is the most abundant element in the Universe. Hydrogen in the low density intergalactic medium is photoionized by radiation from galaxies and other sources, while they remain in neutral form in very high density regions because of shielding. The evolution of neutral hydrogen through cosmic times passes through a number of interesting phases, namely, the dark ages, cosmic dawn, reionization and post-reionization epoch. Understanding each of these phases holds clue about the cosmology and galaxy formation in our Universe. In the talk, we will review our understanding of the physical processes related to cosmological distribution of neutral hydrogen and then present our recent results on these issues.
10:55 Tea
Tea
10:55 - 11:10
Room: Meghnad Saha Auditorium
11:10 Indirect dark-matter searches with gamma-rays experiments : status and future plans from KeV to TeV - Aldo Morselli (INFN)
Indirect dark-matter searches with gamma-rays experiments : status and future plans from KeV to TeV
- Aldo Morselli (INFN)
11:10 - 11:55
Room: Meghnad Saha Auditorium Detection of gamma rays and cosmic rays from the annihilation or decay of dark matter particles is a promising method for identifying dark matter, understanding its intrinsic properties, and mapping its distribution in the universe. I will review recent results from the Fermi Gamma-ray Space Telescope and other space-based experiments, and highlight the constraints these currently place on particle dark matter models. I will also discuss the prospects for indirect searches to robustly identify or exclude a dark matter signal using upcoming experiments at energies below Fermi (ASTROGAM ) and above Fermi, Magic and H.E.S.S. (CTA, LHAASO).
11:55 Many facets of neutron stars: Astrosat and beyond - Biswajit Paul (RRI, Bangalore)
Many facets of neutron stars: Astrosat and beyond
- Biswajit Paul (RRI, Bangalore)
11:55 - 12:40
Room: Meghnad Saha Auditorium We will discuss several interesting aspects of neutron stars that we have pursued over the years along with some very recent results. These include accretion torque, orbital evolution of binary X-ray stars and orbital glitches, quasi-periodic oscillations, self absorption in X-ray pulsars, cyclotron lines in X-ray pulsars, thermonuclear X-ray bursts and their reprocessing etc. We will also discuss some of the important aspects of neutron stars that will be probed in greater detail with ASTROSAT and an X-ray polarimeter and potential use of X-ray pulsars for deep space navigation.
12:40 Neutron Star Research in the SKA-Era - Sushan Konar (NCRA-TIFR, Pune)
Neutron Star Research in the SKA-Era
- Sushan Konar (NCRA-TIFR, Pune)
12:40 - 13:05
Room: Meghnad Saha Auditorium SKA, acronym for the Square Kilometer Array, is going to be the largest Radio Telescope ever conceived. As of 5th October 2015 India has become a full member amongst the countries which would be participating in building this telescope and hence would have the primary data rights. Neutron Star science happens to be one of the priorities of this telescope and would revolutionise the research in this area. This talk would focus on a few typical problems which would majorly benefit from the huge volume of data which would also be of very high quality.
13:05 Lunch
Lunch
13:05 - 14:00
Room: Meghnad Saha Auditorium
14:00 Very High Energy Gamma Ray Astronomy from Hanle - Varsha R. Chitnis (TIFR, Mumbai)
Very High Energy Gamma Ray Astronomy from Hanle
- Varsha R. Chitnis (TIFR, Mumbai)
14:00 - 14:25
Room: Meghnad Saha Auditorium Over a past decade very high energy (VHE) gamma ray astronomy has emerged as a major astronomical discipline. In India, we have a long tradition of experiments in this field. Few years ago, multi-institutional Himalayan Gamma Ray Observatory (HiGRO) collaboration was formed to set up VHE gamma rays experiments at Hanle, a high altitude location in Himalayas. HAGAR, the first phase of this collaboration is operational since 2008. HAGAR has successfully detected VHE gamma ray emission from some of the extragalactic objects like Mrk 421, Mrk 501 as well as galactic sources including Crab nebula/pulsar. Details of HAGAR telescope system and results obtained will be discussed. HiGRO is now gearing up for the next phase, i.e. 21 m diamter MACE telescope, which is being installed at Hanle at present. Details of MACE telescope system and future plans will be discussed.
14:30
14:30 - 18:30
Room: Meghnad Saha Auditorium
Contributions

14:30 Introduction

14:40 The Quantum and the Continuum : Einstein's Dichotomous Legacies - Parthasarathi Majumdar (RKMVU, Belur)

15:10 NA - Naba K. Mondal (TIFR, Mumbai)

15:40 Detecting Supernova Neutrinos by Iron and Lead Detectors - Kamales Kar (RKMVU, Belur)

16:30 Reminiscence Talks

18:00 Talk - Pijushpani Bhattacharjee (SINP, Kolkata)
19:00 Conference Dinner
Conference Dinner
19:00 - 22:30
Friday 16 October 2015
09:00 Direct Dark Matter Searches: Threshold detectors and new techniques - Viktor Zacek (Université de Montreal)
Direct Dark Matter Searches: Threshold detectors and new techniques
- Viktor Zacek (Université de Montreal)
09:00 - 09:45
Room: Meghnad Saha Auditorium This talk summarizes recent activities in the sector of dark matter searches with superheated liquids, and gives an overview of proposed new initiatives for directional searches and new techniques to explore the low mass frontier in the GeV and sub-GeV dark sector.
09:45 Searching for Baryons - Subhabrata Majumdar (TIFR, Mumbai)
Searching for Baryons
- Subhabrata Majumdar (TIFR, Mumbai)
09:45 - 10:30
Room: Meghnad Saha Auditorium The current precision cosmological measurements, in agreement with big bang nucleosynthesis studies, tell us that approximately 95 percent of the Universe is 'dark' and only 5 percent of the Universe is 'visible' which comprises of baryons. However, observations reveal only a small fraction of this baryon budget. A key cosmological question arises as to 'where are these missing baryons?'. Simulations and past observations suggest that some of these are in the diffuse cosmic web. Recently, they have been observed, and speculated, to be hiding in the outskirts of massive halos, from Milky Way type galaxies to clusters. Upcoming surveys have the potential to unravel the mystery of the missing baryons.
10:30 Some theoretical aspects of magnetars - Monika Sinha (Indian Institute of Technology Jodhpur)
Some theoretical aspects of magnetars
- Monika Sinha (Indian Institute of Technology Jodhpur)
10:30 - 10:55
Room: Meghnad Saha Auditorium Compact stars with strong magnetic fields (magnetars) have been observationally determined to have surface magnetic fields of order of 10^14 –10^15 G, the implied internal field strength being several orders larger. We discuss the effect of strong field on the dense matter expected to be inside neutron stars and so called quark stars and hybrid stars. We also discuss its effect on some observational effect which depend the nature and composition of matter inside neutron stars.
10:55 Tea
Tea
10:55 - 11:10
Room: Meghnad Saha Auditorium
11:10 Thermonuclear flame propagation on neutron stars - Sudip Bhattacharyya (TIFR, Mumbai)
Thermonuclear flame propagation on neutron stars
- Sudip Bhattacharyya (TIFR, Mumbai)
11:10 - 11:55
Room: Meghnad Saha Auditorium Accreted matter accumulated on a low magnetic field neutron star intermittently burns via thermonuclear runaway processes, and gives rise to bursts observed in X-rays. During the rise of the X-ray intensity, the thermonuclear flame spreads to engulf the entire stellar surface. Such flame propagation in extreme environment, which is relevant for several branches of physics, is an interesting field in its own right, and is important to probe the super-dense degenerate matter at stellar cores. I will discuss the theoretical and observational aspects of flame spreading, its importance, and why ASTROSAT will be very useful to advance our knowledge.
11:55 Double Beta Decay - Ivan Stekl (Czech Technical University in Prague)
Double Beta Decay
- Ivan Stekl (Czech Technical University in Prague)
11:55 - 12:40
Room: Meghnad Saha Auditorium Experimental searches for neutrino-less double beta decay ($0 \nu \beta \beta$) are one of the most active research topics in neutrino physics. The observation of such process is in fact of major importance since it will prove the Majorana nature of neutrinos and may give access to their absolute mass scale. The Majorana nature of the neutrino would have interesting implication in many extensions of the Standard Model of particle physics. On the other hand, two neutrino double beta decay ($2 \nu \beta \beta$) provides needed information for further development of nuclear theory (nuclear matrix elements). During the talk, the subjects of $0 \nu \beta \beta$ and $2 \nu \beta \beta$ decays, the most important experiments in the field and the obtained results will be introduced.
12:40 Role of backreaction in an accelerating universe - Archan S. Majumdar (SNBNCBS, Kolkata)
Role of backreaction in an accelerating universe
- Archan S. Majumdar (SNBNCBS, Kolkata)
12:40 - 13:05
Room: Meghnad Saha Auditorium It is apparent from several observations that the present universe is undergoing an era of accelerated expansion. On the other hand, the observable universe exhibits inhomogeneities at various scales. The backreaction from inhomogeneities may affect the background metric in a non-trivial way. Here we explore a consequence of such backreaction which may possibly alter the future evolution of the presently accelerating universe, leading to avoidance of the big-rip.
13:05 Lunch
Lunch
13:05 - 14:00
Room: Meghnad Saha Auditorium
14:00 The Highest Energy Neutrinos: Status and Questions - Raj Gandhi (HRI, Allahabad)
The Highest Energy Neutrinos: Status and Questions
- Raj Gandhi (HRI, Allahabad)
14:00 - 14:45
Room: Meghnad Saha Auditorium NA
14:45 The Cherenkov Telescope Array (CTA) - B. S. Acharya (TIFR, Mumbai)
The Cherenkov Telescope Array (CTA)
- B. S. Acharya (TIFR, Mumbai)
14:45 - 15:30
Room: Meghnad Saha Auditorium The Cherenkov Telescope Array (CTA) is a next generation observatory for ground-based gamma-ray astronomy to be built in the near future by an international consortium. The plan is to build 2 arrays one in the southern and the other in the northern hemisphere with hundreds of Imaging Atmospheric Cherenkov Telescopes of assorted size. This will enable to achieve an order of magnitude improvement in the sensitivity and angular resolution and also span a wide energy range of 10 GeV to 10TeV. The CTA will serve as an open observatory to a wide astrophysics community and will provide a deep insight into the non-thermal high-energy universe. It will have a large discovery potential in key areas of astronomy, astrophysics and fundamental physics research which include the study of the origin of cosmic rays and their role in the Universe, the nature and variety of particle acceleration around black holes, and the inquiry into the ultimate nature of matter and physics beyond the Standard Model, searching for dark matter and effects of quantum gravity. In this talk I shall describe the CTA project and its current status.
15:30 Tea
Tea
15:30 - 15:45
Room: Meghnad Saha Auditorium
15:45 How does the Higgs potential survive inflation ? - Subhendra Mohanty (Physical Research Laboratory)
How does the Higgs potential survive inflation ?
- Subhendra Mohanty (Physical Research Laboratory)
15:45 - 16:30
Room: Meghnad Saha Auditorium After the discovery of the 125 GeV mass Higgs, it was shown that the value of the Higgs quartic coupling becomes negative on renormalization at high energies. The energy scale at which the Higgs potential becomes unstable is 10^(11) GeV. During inflation quantum fluctuations will drive the vev of the Higgs field to $< \phi^2 > ~ H^2, where H the expansion rate of the scale factor at the time of inflation is expected to be 10^{14} GeV. Therefore during inflation the Higgs field will roll down to large negative values. This inconsistency between Higgs potential and inflation even when the Higgs field is not the inflation is an open problem. I will discuss ways on which this problem has been solved by introducing new physics beyond the standard model. I will also discuss one idea where the solution to the Higgs instability problem is provided by the Hawking-Gibbons temperature of the de-Sitter space during inflation.
16:30 7 keV sterile neutrino dark matter in U(1)_R-lepton number model - Sourov Roy (IACS, Kolkata)
7 keV sterile neutrino dark matter in U(1)_R-lepton number model
- Sourov Roy (IACS, Kolkata)
16:30 - 16:55
Room: Meghnad Saha Auditorium I shall discuss about keV sterile neutrino dark matter in a supersymmetric model with U(1)_R symmetry in the light of a recent observation of an X-ray line signal at around 3.5 keV, detected in the X-ray spectra of Andromeda galaxy and various galaxy clusters including the Perseus galaxy cluster. In this model the U(1)_R symmetry is identified with lepton number. The model provides a small tree level mass to one of the active neutrinos and also renders a suitable warm dark matter candidate in the form of a sterile neutrino. Light neutrino masses and mixing can be explained once one-loop radiative corrections are taken into account. The scalar sector of this model can accommodate a Higgs boson with a mass of ~ 125 GeV. In this model gravitino is the lightest supersymmetric particle and we also discuss the cosmological implications of this light gravitino with a mass of order GeV.
16:55 Direct Dark Matter Searches and future prospects - Venktesh Singh (BHU, Varanasi)
Direct Dark Matter Searches and future prospects
- Venktesh Singh (BHU, Varanasi)
16:55 - 17:20
Room: Meghnad Saha Auditorium NA
17:20 Parallel
Parallel
17:20 - 18:55
Room: Meghnad Saha Auditorium
Contributions

17:20 Two neutrino double electron capture measurement using pixel detectors - Joshy M. jose (Czech Technical University in Prague)

17:20 Entropy Functional and Second Law in Curvature Squared Gravity - Srijit Bhattacharjee (IIT Gandhinagar)

17:40 Impact of sterile neutrinos on CP measurements at DUNE - Mehedi Masud (HRI)

17:45 HIgher spins as saviour of Quantum Universe - Rudranil Basu (Indian Institute of Science Education and Research, Pune)

17:55 The Direct Detection of Boosted Dark Matter at High Energies and PeV events at IceCube - Aritra Gupta (HRI, Allahabad)

18:10 Exploring Octant and CP violation at DUNE in presence of Reactor Experiments - Debajyoti Dutta (HRI, Allahabad)

18:10 The k-essence scalar field in the context of Supernova Ia observations - Arka Moulik (RKMVU, Belur)

18:25 Exploring Non Standard Physics in Long-Baseline Neutrino Oscillation Experiments - Sabya Sachi Chatterjee (Institute of Physics, Bhubaneswar)
Saturday 17 October 2015
09:00 LZ: A 2nd Generation Dark Matter Direct Search Experiment - Mani Tripathi (UC Davis)
LZ: A 2nd Generation Dark Matter Direct Search Experiment
- Mani Tripathi (UC Davis)
09:00 - 09:45
Room: Meghnad Saha Auditorium The LZ collaboration has proposed a 2nd generation direct dark matter search experiment, which builds on the experience gained with the LUX and ZEPLIN series of experiments on the two-phase xenon TPC technique. It features an active target volume of ~7 tonnes and a robust 3-layer shield system consisting of a xenon skin volume and a liquid scintillator veto, embedded in the existing 6m diameter water tank at the 4850' level of the Sanford Underground Research Facility. We have developed a novel design for the liquefaction, recirculation and purification for this unprecedented large volume of xenon. Our studies of backgrounds are comprehensive and predict a fiducial volume larger than 5 tonnes, in which the dominant electron and nuclear recoil backgrounds are from astrophysical neutrinos. The projected sensitivity for a 1,000 day running period for the WIMP-nucleon cross section is below 2.5x10^-48 cm^2 at a WIMP mass of 50 GeV. We will present some details of the advanced design of LZ, the background model, and our physics goals.
09:45 Cosmic Accelerators with H.E.S.S. - Nachiketa Chakraborty (Max-Planck-Institut fuer Kernphysik)
Cosmic Accelerators with H.E.S.S.
- Nachiketa Chakraborty (Max-Planck-Institut fuer Kernphysik)
09:45 - 10:30
Room: Meghnad Saha Auditorium The High Energy Stereoscopic System (H.E.S.S.) has provided a view of the Galactic Plane as well as the extra-Galactic sky in the southern hemisphere with unprecedented sensitivity. It has revealed powerful particle accelerators via their TeV emission within and outside the Galaxy showing their spatial, spectral and temporal characteristics. This helps us understand the physics of the individual sources as well as their environment. The studies of active galactic nuclei (AGN) in particular enable us to do TeV cosmology probing the extra-Galactic background light (EBL), as well as Lorentz Invariance violating effects. The addition of the new 28 m^2 telescope enables observations down to lower energies (< 100 GeV) and with better energy resolution. This allows to push further on all the aforementioned fronts. In this talk, I will highlight some of the more recent exciting results from H.E.S.S. on the Galactic Center, the Large Magellanic Clouds as well as the Active Galactic Nuclei and their implications on astroparticle physics in general.
10:30 General relativistic viscous accretion disc and generation of bipolar jets - Indranil Chattopadhyay (ARIES, Nainital)
General relativistic viscous accretion disc and generation of bipolar jets
- Indranil Chattopadhyay (ARIES, Nainital)
10:30 - 10:55
Room: Meghnad Saha Auditorium We revisit the general relativistic viscous accretion disc. As in Newtonian fluid, the viscous tensor is proportional to the shear tensor in relativistic fluid too, and the constant of proportionality is the constant of viscosity. However, in relativity the shear tensor is much more complicated, containing four accelerations, gradient of three velocities, expansion of world line terms etc. This inherent complication makes a consistant study of viscous accretion discs around black holes very difficult. In this presentation, we solve the equations of general relativistic viscous disc in steady state. We show that such accreting flows may admit shock waves. The extra heating term in the post-shock disc may spew out bipolar jets. In order to determine the jet streamline and jet cross section we obtained the corresponding von Zeipel cylinders. We then trace the matter that will escape through these surfaces. We also show that 4 to 5 % of accreting matter escapes as bipolar relativistic jets. Comparison with Newtonian plus pseudo-Newtonian and the pure general relativistic studies shows that the jets are much stronger in the latter case. And finally we discuss the observational implications.
10:55 Tea
Tea
10:55 - 11:10
Room: Meghnad Saha Auditorium
11:10 Nucleosynthesis in neutron star crust - Sarmistha Banik (BITS Pilani, Hyderabad)
Nucleosynthesis in neutron star crust
- Sarmistha Banik (BITS Pilani, Hyderabad)
11:10 - 11:35
Room: Meghnad Saha Auditorium NA
11:35 Nonthermal Two Component Dark Matter Model for Fermi-LAT $\gamma$-ray excess and 3.55 keV X-ray Line - Anirban Biswas (HRI, Allahabad)
Nonthermal Two Component Dark Matter Model for Fermi-LAT $\gamma$-ray excess and 3.55 keV X-ray Line
- Anirban Biswas (HRI, Allahabad)
11:35 - 11:55
Room: Meghnad Saha Auditorium A two component model of nonthermal dark matter is formulated to simultaneously explain the Fermi-LAT results indicating a $\gamma$-ray excess observed from our Galactic Centre in the 1-3 GeV energy range and the detection of an X-ray line at 3.55 keV from extragalactic sources. Two additional Standard Model singlet scalar fields $S_2$ and $S_3$ are introduced. These fields couple among themselves and with the Standard Model Higgs doublet $H$. The interaction terms among the scalar fields, namely $H$, $S_2$ and $S_3$, are constrained by the application of a discrete $\mathbb{Z}_2\times \mathbb{Z}^\prime_2$ symmetry which breaks softly to a remnant $\mathbb{Z}^{\prime \prime}_2$ symmetry. This residual discrete symmetry is then spontaneously broken through an MeV order vacuum expectation value $u$ of the singlet scalar field $S_3$. The resultant physical scalar spectrum has the Standard Model like Higgs as $\chi_{{}_{{}_1}}$ with $M_{\chi_{{}_{{}_1}}}\sim 125$ GeV, a moderately heavy scalar $\chi_{{}_{{}_2}}$ with $50 \,\,{\rm GeV} \leq M_{\chi_{{}_{{}_2}}}\leq 80\,\,{\rm GeV}$ and a light $\chi_{{}_{{}_3}}$ with $M_{\chi_{{}_{{}_3}}} \sim 7$ keV. There is only tiny mixing between $\chi_{{}_{{}_1}}$ and $\chi_{{}_{{}_2}}$ as well as between $\chi_{{}_{{}_1}}$ and $\chi_{{}_{{}_3}}$. The lack of importance of domain wall formation in the present scenario from the spontaneous breaking of the discrete symmetry ${\mathbb{Z}_2^{\prime\prime}}$, provided $u\leq 10$ MeV, is pointed out. We find that our proposed two component dark matter model is able to explain successfully both the above mentioned phenomena $-$ the Fermi-LAT observed $\gamma$-ray excess (from the $\chi_{{}_{{}_2}} \rightarrow {\rm b} \bar{\rm b}$ decay mode) and the observation of the X-ray line (from the decay channel $\chi_{{}_{{}_3}}\rightarrow\gamma \gamma$) by the XMM-Newton observatory.
11:55 To Lambda or not to Lambda? - Supratik Pal (ISI, Kolkata)
To Lambda or not to Lambda?
- Supratik Pal (ISI, Kolkata)
11:55 - 12:40
Room: Meghnad Saha Auditorium NA
12:40

12:40 - 13:00
Room: Meghnad Saha Auditorium

13:00 Lunch & Closing
Lunch & Closing
13:00 - 14:00
Room: Meghnad Saha Auditorium

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