Srubabati Goswami


Research Summary:

The year 2002 has witnessed two very important results in solar neutrino research. In April 2002 the accumulated evidence in favor of possible flavor conversion of the solar electron neutrinos was confirmed with a statistical significance of 5.3$\sigma$ from the Sudbury Neutrino Observatory (SNO) and picked out the Large Mixing Angle (LMA) MSW solution as the preferred solution. In December 2002 the Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) experiment in Japan provided conclusive evidence in favor of $\bar{\nu_e}$ oscillation and confirmed the LMA solution (assuming CPT invariance), using reactor neutrinos.

We have performed model independent and model dependent analyses of solar neutrino data including the neutral current event rate from SNO and determined the values of neutrino mass and mixing angles consistent with the current data.

We have also investigated the status of the neutrino decay solution to the solar neutrino problem in the context of the SNO results for both two and three generation cases with one of the mass states being allowed to decay and include the effect of both decay and mixing. We find that the Large Mixing Angle (LMA) region which is the currently favoured solution of the solar neutrino problem is affected significantly by decay. We obtain bounds on the decay constant $\alpha$ in this region.

In this period I have done three works with my collaborators on the implication of the KamLAND data. In the first work we had investigated the potential of the KamLAND experiment and studied its projected sensitivity over a 3 kton-year exposure. In the second work we have done a global analysis of solar and the recently announced KamLAND data and investigate its effect in constraining the mass and mixing parameters. In the third work we probe the sensitivity of the solar neutrino experiments and KamLAND to the neutrino mixing angle. We conclude that even after 3 kton-year of statistics and most optimistic error estimates, KamLAND may find it hard to significantly improve the bounds on the mixing angle obtained from the solar neutrino data. We propose a new reactor experiment which can give the value of $\tan^2\theta_{12}$ to within 14%.

I am involved in the Indian Neutrino Observatory project and have done studies pertaining to event generators using the NUANCE neutrino generator and detector simulation using the GEANT package. I am also involved in studying the Physics potential of the ICAL detector in INO in comparison with other upcoming detectors like MINOS.

I am doing some study on Supernova Neutrino detection in future experiments as well as on high energy (1 -100 GeV) neutrinos coming from trapped dark matter particles in the sun.

Publications:

  1. Solar neutrino experiments: An overview
    S. Goswami, arXiv:hep-ph/0303075, to appear in the special issue on Neutrino Physics of the Proceedings of the Indian National Academy of Sciences.

  2. Exploring the sensitivity of current and future experiments to $\theta(\odot)$
    A. Bandyopadhyay, S. Choubey,S. Goswami, arXiv:hep-ph/0302243, to appear in Phys. Rev. D.

  3. The solar neutrino problem after the first results from KamLAND
    A. Bandyopadhyay, S. Choubey, R. Gandhi, S. Goswami and D. P. Roy, Phys. Lett. B 559 (2003) 12.

  4. Implications of the first neutral current data from SNO for solar neutrino oscillation
    A. Bandyopadhyay, S. Choubey, S. Goswami, D.P. Roy, hep-ph/0204286, Phys. Lett. B 540, 14 (2002).

  5. Neutrino Decay Confronts the SNO data
    A. Bandyopadhyay, S. Choubey, S. Goswami Phys.Lett.B555:33-42,(2003).

  6. Progress in Neutrino Oscillation Searches and their implications
    S. Goswami
    Pramana, Vol 60, No. 2, 261, 2003.

Preprints:

  1. Testing the solar LMA region with KamLAND data
    A. Bandyopadhyay, S. Choubey, R. Gandhi, S. Goswami and D. P. Roy, arXiv:hep-ph/0211266.


Conference/Workshops Attended:

  1. PASCOS'03, Tata Institute of Fundamental Research, Mumbai, January 2003.
  2. NEUPAST, ICTP, Italy, September 2003.
  3. Interaction meeting of INO collaboration, SINP, Kolkata, 31 March to 2nd April, 2003.

Visits to other Institutes:

  1. International Centre for Theoretical Physics, 16th September to 3rd October 2002.
  2. Tata Institute for Fundamental Research : 2nd - 11th January, 2003.
  3. Saha Institute Of Nuclear Physics 29th January to 7th February, 2003, 31st March to 2nd April, 2003.

Invited Lectures/Seminars:

  1. Solar Neutrino Oscillation Phenomenology, , Plenary Talk, PASCOS, 03, TIFR, January 2003.
  2. Some Recent Developments in Neutrinos and Flavour Physics - HarishChandra Research Institute, October 2002.
Other Activities:
  1. I am a member of the INO collaboration and a joint co-ordinator of the Simulation and Physics Group
  2. I am currently a working group co-ordinator in the Neutrino and Astro particle Physics group in the Workshop on High Energy Physics Phenomenology to be held in IIT Bombay in January 2004.
  3. I gave the course on Computational Physics to the first year graduate students
  4. R. Srikanth from University of Hyderabad has done a one month reading project on solar neutrino oscillations with me.

 



© Harish-Chandra Research Institute