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Institute of Physics, Bhubaneswar

An Autonomous Research Institute of Department of Atomic Energy, Govt. of India

  In Memory of Professor Durga Prasad Roy

DP Photo

Professor Durga Prasad Roy

29th July 1941 ‐ 17th March, 2017

Our beloved Professor Durga Prasad Roy (29th July, 1941 - 17th March, 2017), an internationally renowned stalwart of particle physics and pilar of Indian high energy physics, passed away on 17th March, 2017 in the early morning in Cuttack, Odisha after a brief illness.

Brief CV:

Professor Durga Prasad Roy got BSc from Ravenshaw College, Cuttack and MSc from Delhi University. He did his PhD in 1966 from TIFR, Mumbai, in particle physics. He was a postdoctoral Fellow at the University of California (1966-68), CERN, Geneva (1968-69), and University of Toronto (1969-70). Then, he worked at the Rutherford Laboratory, UK (1970-74), and then as Reader at Visva Bharati University, India (1974-76). He joined TIFR as Reader in 1976 and retired as Senior Professor in 2006. Then he worked in the Homi Bhabha Centre of Science Education, TIFR, as DAE Raja Ramanna Fellow till 2011 and was working at HBCSE as INSA Senior Scientist since then.

Physics Contribution:

  • Prof. DP Roy made pioneering contributions in the wide area of particle and astroparticle physics.
  • He predicted and presented evidences for exotic meson (tetra-quark) and baryon (penta-quark) states.
  • The signature for top quark search in terms of a hard isolated lepton and jets, suggested by him, has been widely used in the top quark search at the CERN and Tevatron proton-antiproton colliders, leading to its discovery at the latter in 1995.
  • He suggested a promising signature for the charged Higgs boson search in its tau lepton decay channel, using the distinctive polarization prediction for tau. This is being currently used in the ongoing search for charged Higgs boson at the Tevatron as well as the Large Hadron Collider at CERN.
  • Likewise, the missing transverse-momentum signature for Supersymmetric particles suggested by him, is being widely used in the ongoing collider searches for these particles.
  • In the Golden Years of Solar Neutrino Physics 2000-05, he was deeply involved in analyzing the experimental data with his collaborators to finally provide a unique solution to the long-standing Solar Neutrino puzzle in terms of Neutrino Oscillation with precise mass and mixing angle through a series of globally acclaimed papers.

Awards & Recognitions:

  • His scientific achievements were recognized in form of the Meghnad Saha Award conferred by UGC and the SN Bose Medal awarded by INSA (2007).
  • He was elected Fellow of the Indian Academy of Sciences, Bangalore, and National Academy of Sciences (India), Allahabad, along with INSA.

Teaching

  • Prof. DP Roy was passionate about undergraduate teaching, and was active in the National Initiative in Undergraduate Science (NIUS) program of HBCSE as a mentor and the student's journal of physics published by IAPT as Member of its National Advisory Board.
  • He also taught in the 5-year integrated MSc program of the DAE-MU Center of Excellence in Basic Science as a visiting faculty.
  • He played an important role to start the SERC school and the WHEPP workshop in our country to build a strong particle physics group.
  • He served as the member of the Governing Council of our Institute and helped us all the time to improve our academic visibility.
He leaves behind a loving wife Monika, and a daughter Kalyani and many physicists like us who were inspired and taught by him at various stages of life.

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They Say...


Professor Roy was greatest physicist of the present time.

M.Ibrahim Mirza,  Potential PhD Student at Christ Church College , Kanpur University

I first met DP @ WHEPP in Ahmedabad, and I had just started my first postdoc. I hardly knew anyone in the community, and I was bit hesitant! The very first day, he approached me saying "I am DP! very good to see a news young face .." .. In the end he guided me already how I should approach my postdoc, my possible job application in India. By the time, I left WHEPP he became so familiar to me! From then on, he was always very interactive, specially to all young people - making them immediately comfortable. Later, in many conferences/workshops I had taken long walks in the evening with him, and he told so many stories of his generations! Last time, when I met him @ IITK, WHEPP, he asked me whether I can teach @ a Summer School in south. I agreed .. but he is no more there to follow up! Recently, at SINP, we also had a memorial meeting, and we got to know about his work, and how is being respected by his colleagues and peers! He will be missed heavily by the community ..

Koushik Dutta,  Faculty at Saha Institute, Kolkata

I first met Prof DP Roy at University of Hyderabad during a workshop on High Energy Physics from 6-11 March 2017 . Prof DP Roy was a great personality , scientist and fun loving person. After a week later, I came to know about Professor's sudden death. It was a great shock for me. My heartiest condolences to Prof DP Roy's family. May his soul rest in peace.

Ashish Sharma,  Research Project Fellow at Central University of Himachal Pradesh, Dharmashala

I was taken aback by passing of my good friend DP. In January we were both visiting IMSC, and he was his usual self, very enthusiastic, and gave a set of lectures on Neutrino Physics. Over the years, I have known him from early 80's. I always admired his love of phenomenology, and great insight in new discoveries. I also remember fondly his visit to Oregon. My heart goes out to his family to whom this must have as a great shock.

Nilendra Deshpande,  Professor of physics at University of Oregon

Only yesterday, I heard this sad news from Prof Spanta Wadia,ICTS,Bangaluru, who visited us .I cannot believe that Durga da (the way I addresses DP) is no more. A fiend , collaborator and mentor, since last four decades, l will remember Durgada foryears to come.I convey myheartfeltcondolences to the loving family.It is a great loss to Physics Community of India

Dilip Kumar Choudhury,  President at Physics Academy of the North East(PANE),Guwahat and Former Professor of Physics, Gauhati University ,INDIA

I knew Prof. D.P. Roy from the time I joined IOP in 1994. I was struck by his passion for Physics and his general concern for the HEP community in general. At the same time he was deeply concerned about undergraduate education (about which my association with him continued through the Student Journal of Physics, and HBCSE). I think anyone who knew him also was affected by his very strong personality, to some extent dominating. Honestly, in the beginning I was not prepared for it, being a young scientist. But later on, as I came to know him closer, I could see (as anyone else), that all this comes because of his deep, and very honestpassion for physics. How many people we know how can almost have tears in their eyes when expression concern about lack ofwholesome training manyHEP students receive these days. He cared bout students, about young faculty members, and about the entire community. No HEP conference, let alone the WHEPP, will ever be the same without him. People like him do not pass away. We will remember him in every HEP gatherring, and inall sessions of WHEPP.My deeepest condolences for the family members of Prof. Roy, also to his extended family which is the entire HEP community as well as undergraduate students who ever came in his contact.

Ajit M Srivastava,  Professor at Institute of Physics Bhubaneswar

I met him first time in Kathmandu (BCSPIN). Both we went for swimming nearest river and became very friendly. After that we met many times in many occasions at Udaypur, Germany and IOP etc. He had helped me to enhance in my career, which is commendable and memorable through out my life. He was nice and wonderful human being. It is a great loss to Physics community as well as society. I express my deepest condolence to Prof. D. P. Roy and pray GOD for his soul in rest.

PRADIP KUMAR SAHU,  Associate Professor at Institute of Physics

I knew Durga Prasad Roy from my school days. Our families were very close. I addressed him as Nuli-da. He inspired me in many ways during my academic career. He stood by me in vary many difficult times. I have lost a brother.Our long relationship goes back to three generations. The following correspondence in connection with the passing away of my mother is one example.Dear Babuli: I have found solace and strength from Tagore's writingsto bear the death of dear ones because he has repeatedly faced thesame grief, and learned to respect death as communion with God andthe resulting pain on you as His gift to help you prepare anddedicate yourself better for His task. The only thing that bothers methough is the suffering of being bed ridden for oneself and one'snear ones. I am reminded by your mail about my mother making the sameplea to Chhaba - to give her some poison to end her suffering. On amore positive note, I am grateful to Krushna Apa for coming all theway to unveil father's bust,and give a touching speech on the occasion. She said she used toaddress your grand parents as mother and father; and for her and theSarvodaya family Biraja Bhai was the Hanuman who would jump to theend of the world with the the slight lift of mother's finger.As regards Ekla Chalo, you have still to fulfill your task of gettingAnshuman settled and present you with a grand child (hopefullydaughter). I shall try to phone you later today. Best wishes.--NuliDear Babuli: Sad to learn about the death of your revered mother. Shewas a noble lady, whose death can be aptly described as return to herheavenly abode like the mother Ganga in Mahabharat. But for us mortalsthe death of one's mother is an irreparable loss. My deepestcondolences.--Nuli

Jnan Maharana,  Senior INSA Scientist at Institute of Physics

Very good physicist.

ANUP DAS,  Student at Karimganj College, Karimganj.

I express my deep condolence to the departed Prof. D. P. Roy. May his soul rest in Heavenly adobe.

Dr. Sabyasachi Roy,  Sr. Asst. Prof at Karimganj College

It was a big shock for me when I heard that prof. D P Roy passed away on 17th March 2017. I still remember his smiling face when we met just a few days before of this incidence. Both of us were invited by Prof. Rukmani Mohanta to give lectures in the school of Physics, central University, Hyderabad. He was giving lectures on physics of Standard Model and Beyond, while I was giving lectures on Dark Matter. He was utmost fit like me though our age difference is about 36 years. We were having lunch together. He was telling about his plan of visiting IOP, Bhubaneswar and subsequently to his native place in Odisha for playing HOLI. After that he would like to go back to his work place Mumbai. But who knew that it was his last visit... He also told us that he is currently learning General Theory of Relativity in curved space and its application. At the age of 76, he was learning something new to him. It was a great inspiration for me and of course to all new generation physicists. Since both of us from Odisha, we used to gossip in Oriya about physics and other subjects. I still remember we used to share a room in WHEPP-XIV held in IIT Kanpur in December 2015. He told me that he is old and will not come any more. Probably he was right... I didn't have any interaction with his family members. But my heartfelt condolence goes to them.

Narendra Sahu,  Associate Professor at Department of Physics, IIT Hyderabad, India

I am greatly shocked to read the news that DP is no more.It is difficulty to accept get the loss of a dear friend and colleague of more thanhalf a century. I valued greatly his knowledge of experiments and no nonsenseapproach to solving problems. Kindly convey to Monica and Kalyani our heartfeltcondolences.

J.Pasupathy,  Retired Professor at CHEP, Indian Insitute of Science

I first met Prof. DP Roy as a post-doctoral fellow when I came to give a talk at TIFR. He was extremely kind and made me feel very comfortable. In later years we met several times at PRL and at conferences and it was always a pleasure to talk to him about physics and other subjects. His contributions to particle physics are immense, but equally important was his role as a warm and generous colleague.

Raghu Rangarajan,  at Physical Research Laboratory, Ahmedabad

Durga Prasad Roy, Friend and Physicist.When he joined our M. Sc. (Physics) class at Delhi University in 1960 , he had the unlikely distinction of being the heavy weight lifting champion of Orissa. Later I learnt that he was also an expert swimmer and his skills had been honed in the 'Mahanadi' in Orissa.He loved Rabindra Sangeet and had a deep interest in India's freedom struggle. He made friends readily , and was generous in inviting class mates to lunch at his University residence hall. We also enjoyed having outstanding teachers including DS Kothari, RC Majumdar and Asoke Mitra. After his Ph. D. at TIFR , he used to describe himself as a 'poor phenomenologist'. By sheer hard work and an instinct for what is important, his research work kept pace with the latest developments in high energy phenomenology. When he joined TIFR in 1976 after post doctoral work at Riverside, CERN, Toronto, Rutherford lab and Visva Bharati, he had already achieved considerable fame. Our colleague Pasupathy at TIFR used to say that his initials DP stood for Dual Pomeron. This phase of his research continued upto his Physics Reports paper in 1980 (with SN Ganguli) on Regge phenomenology of inclusive reactions . His interests soon expanded to various aspects of collider physics (LEP, Tevatron, LHC) to include signals for top quark and charged Higgs searches at colliders, SUSY particle searches, and to various aspects of neutrino oscillations. A ringside glimpse into these researches is given by Sandip Pakvasa and Rohini Godbole in this web page. DP had an outstanding student, Rajiv Gavai, and a galaxy of collaborators including R Godbole, M. Guchait, U. Chattopadhyay, U. Sarkar. E. Ma, M. Drees, V.Barger, RJN Philips, S. Pakvasa, E. Reya, R. Roberts. He also had very good friends among non-collaborators, including Sudhendu Rai Choudhury, Vijay Shankar Varma, Dipan Ghosh and Jnan Maharana. He took substantial initiatives in starting (with P. Roy) a series of very successful workshops (WHEPP) on high energy physics phenomenology . He was forthright and outspoken in all matters, scientific or otherwise.His stay at the Homi Bhabha centre for Science Education (2006-2017) initiated by Arvind Kumar , revolved around their program 'NIUS', National Initiative on Undergraduate Science. He guided student projects and lectured extensively on high energy physics. I too joined this excellent program of HBCSE in 2009 ,through Prof. H. C. Pradhan, the centre director at that time. Our offices were adjacent and we lived in the same building. So, we often gave rides to each other. During some of these journeys he described in detail his proposition that Indian Science was stagnant for about one thousand years after the end of the ninth century due to lack of interaction between experimental investigations and theoretical analysis. He published this in the Indian journal of history of science (2016). About a year back, DP also undertook an ab initio self study of Gravitation from a book which you will see on his desk if you now peep through the glass door of his office. About two months back he requested me to check his calculation of a metric which did not agree with that given in the book. His calculation was right.I had the privilege of attending DP's wedding to Monika in 1968 in Orissa. My wife Nandita and I and our children know his family including Monika, elder daughter Kaberi (expired), and younger daughter Kalyani from the thirty years we stayed together in the TIFR housing colony.About the end of the first week of March 2017, DP joined me in an evening walk in the park, and told me that next day he was leaving for Hyderabad ( for lectures) and Orissa for about a 10-day trip. I told him, but you have just come back from the gruelling journey of South India including Chennai and Kanya Kumari ! He smiled and said, but this will be the last trip. He also said that he had nearly recovered from a bout of cough after taking some antibiotics. So he was fit.On the night of 15th March came a call from Monika that DP was unwell; on the 16th morning that he was admitted to a nursing home in the outskirts of Cuttack, and on the 17th early morning that it was all over. We were devastated. It was a bolt from the blue for everyone who knew him , and knew him to be fighting fit. We are shocked ,frustrated and sad that there was no time to arrange effective medical help. It is a great loss. I cannot find words to console Monika and Kalyani.S. M. Roy

Shasanka Mohan Roy,  INSA Honorary Scientist at HBCSE, TIFR

I got acquainted with Prof. D P Roy in his last Avatar. After a splendid research career at TIFR he joined HBCSE as a Raja Ramana Fellow some ten years ago. At that time I was the National Coordinator of a fledgeling program to shore up undergraduate science education in the country, namely, the National Initiative on Undergraduate Science (NIUS) and I invited him to help out. Prof. Roy, who had earlier worked at the far frontiers of physics, gamely did so. He reinvented himself and put his shoulder to the wheel. He was a wonderful resource person and I recall many conversations and debates with him in NIUS camps and in our HBCSE canteen. I recall his pedagogical article explaining Olber's paradox in the magazine. Resonance. And also his support to the Student Journal of Physics aimed at UG students. The Olber's paradox is about the night sky - and why, if all stars are as luminous as our sun, the night sky is not brilliantly lit up? Tonight, as I go out and llok up at the night sky, I will once again recall his pedagogical explanation, I will think about him, about the affection and respect I had for him, emotions closeted in one's heart but regretfully never expressed.

Vijay A Singh,  Raja Ramana Fellow at CBS, Mumbai

I knew DP as a colleague for over 25 years. He was a prominent member of the particle physics community. Our families overlapped at TIFR over the years and we interacted with each other on many occasions. Leena often traveled with Monika on the TIFR bus and their friendship began there. Neha and Varun knew Kalyani and Kaberi. They were especially fond of Kaberi who was a regular at playtime at the Bhaskara colonade. Neha was very proud to have been the winner of the inaugural Kaberi memorial concert that the family organised. Our most sincere condolences to Monika and Kalyani.

Spenta Wadia,  Professor Emeritus at ICTS-TIFR, Bangalore

I had the privilege to interact with Prof.Roy at WHEPP-2013 and had a memorable trip with him to Chilka Lake. During the trip we kept discussing over physics and other myriad topics and also on mythology. During his recent visit to SINP for a colloquium, where he had stressed on the need of doing experiments, also brought back many old discussions. Surely I will miss your smile Prof.Roy.

Debasish Das,  Associate Professor at SINP kolkata

In this LHC era a sizable contribution to LHC phenomenomenology comes from India. The bulkof it has been inspired by DP either directly or indirectly. My generation of Indian phenomenologists and many belonging to the next, learned collider physics directly from him through lectures and collaborations and when we started teaching our students D.P was always an inspiration. His help was not restricted to academic discussions only. He would always extend a helping hand to a younger colleague struggling to establish himself/herseelf. I would always gratefully remenber his help, guidance and encouragement.

Amitava Datta,  Professor (Retd) at Jadavpur University and IISER Kolkata

For me, Durga-da played the dual role of a mentor and a friend. When I came back to India in 1994, he helped me a lot in my efforts to get acquainted to the India Particle Physics community which, at that time, was largely unfamiliar to me. We have also had many discussions on Physics, on teaching Physics, and even on History of Science which became his passion in the last few years of his life. All of these discussions were very enriching for me. He was 76, so I cannot complain that his death is an immature one, but I dearly wish that I could have had the opportunity of interacting with him for some more years.

Palash Baran Pal,  Senior Professor at Saha Institute of Nuclear Physics

It is a great loss to the entire Physics community . As a great ambassador of Physics Durga Sir will be remained in our heart. Love you Sir and RIP.

Shakti Shankar Acharya,  Research fellow at Dept. of Physics, I.T.E.R., SOA University, Bhubaneswar

Really great!!! . .A king of Physics with good carrier.. .Love you so much sir. .A great human being by all of us who came across him. My heartfelt condolences to his family, colleagues and students. I wish some of us follow him from where he left.

Udit Pratap Gahir,  Student (Studying M.Sc Applied Physics with Specialization Materials Science) at Dept. of School Of Applied Science -Centurion University, Bhubaneswar

Durga-da was like an elder brother looking after my good and bad days in pursuing work at TIFR and SINP. My first interaction with him was through work when I presented a work on my post-doctoral work at IC at TIFR during my visiting fellowship days in 1978. He was the only physicist in the audience who showed serious interest in that work. It was the report of a strange bump which we observed in antiproton-proton interactions. He was working in those days on baryonium and penta-quark was not a popular name in those days. During my days at TIFR he was one of my mentors. He was a great physicist and inspired the younger people all around him. It was my good luck that I met him last November in Bombay when he came to attend a colloquium by Daniel Denegri. Both he and I were excited to meet each other. He will be remembered as a great human being by all of us who came across him.

Sunanda Banerjee,  at Fermilab

Widely respected teacher and researcher that Prof Roy was, he was a true gentleman and father-figure to many of us. It's a rude shock to us that he is no more amongst us. It's a great loss to the scientific community. My heartfelt condolences to his family, colleagues and students. I wish some of us follow him from where he left.

Arindam Bose,  Asst Professor at Tata Institute of Social Sciences

I knew Durga (DP) when he came to Riverside as a postdoc in 1966, I was doing my Ph.D. that time. We, and some other junior students were very close, spending many evenings together. I have met him several times during my visit to TIFR. He was indeed a wonderful person, in addition to being a great physicist. I was looking forward to seeing him at the Institute of Physics the day he suddenly became ill. His passing away is a great shock. I and my wife convey our deepest sorry to his wife and daughter, for the loss of a wonderful man.

S. D. Mahanti,  Profrssor Emeritus at Michigan State University

Prof. D. P. Roy was a great teacher and a great motivator for many of us. His soft words with his signature smile will always be remembered. I don't know when there will be another person like him explaining students finer issues of particle physics phenomenology.

Durga Mahapatra,  Retd Professor at Institute of Physics, Bhubaneswar

Terribly sad news. Lots of lovely moments spent together with DP, even when quarrelling, resurface in my memory. Also that last dinner in his home in Geneva, when DP and Mono could not agree on when to put the chicken in the curry and Steve and I had to decide in the end. It all started off with DP addressing me one day in RAL with: `you are a bright young man, but utterly confused' (on charged Higgs matters that was, it turned out he was right). That was the beginning of a collaboration and also a friendship, the latter outlasting the former. I will miss him, the warmth of his heart and his mischievous smile. RIP, dear DP.

Stefano Moretti,  Professor at The NExT Institute, Southampton & RAL

I started my work with Prof. D.P. Roy just after joining as apost-doctoral fellow in TIFR. My collaborative works with Prof. Roy continuedfor about 14 years. This involves analyses involving HyperbolicBranch/Focus point scenario of mSUGRA, various dark matter/collider analysesbased on Non-universal gaugino mass scenarios etc. It was amazing to see hisenergy and strong intuition in various physics issues. I also appreciatedhis writing skill. Most of the time he used to write with a minimum amountof change. He was always very supportive toward my work and career ingeneral. Whenever I used to disagree with him, I remember of writing long emails to make him understand my point. At a personal level, Ialong with my family enjoyed his affection and warmth. Most recently,he visited IACS in February 2017. On his day of departure I tried tosee him off in the morning since I was around IACS for some reason. It was not pre-scheduled, thus he was not aware. Although, I was on time, I found that it was he who left a bit early. I could only have a glimpse of his car moving in the opposite side of the road. It was indeed a vacant feeling. After a month, I again found him leaving a bit early, this time forever, without giving anyhint. I wish his family gather strength to cope up with his demise.

Utpal Chattopadhyay,  Professor at IACS, Kolkata

This is really sad news. DP was one of the most active and versatile physicists in Indian high energy physics. He was known in physics circles all over the world.He was especially visible at conferences and interacted readily with people he met. His pleasant,outgoing personality made him friends everywhere. DP had a special attachment to Aachen, as his brother had studied and obtained his Doctorate here. As a result our families got to know each other quite well. I have many happy recollections of meeting him at various places (including Rutherford Lab and Dortmund), and on the occasions that I visited India. Please convey my deepest sympathy to his family. He will be missed by all who knew him.

Lalit Sehgal,  Senior Professor at RWTH Aachen University

Profoundly saddened by the news. The suddenness of his demise hits hard ! He was a great mentor and supporter for me in the 80's as well as, for many more young researchers in the country who were striving hard under considerable disadvantage, to gain a foot-hold in the research-arena. His stewardship in the organization of DAE-symposia, WHEPP and other meetings on a regular basis, for the HEP-community of the country will be remembered with gratitude. A tremendous loss, therefore, for the HEP-Community and a personal loss for me. Praying for his peaceful rest, after such an active life devoted to physics to his very last moment,Bimal Mahapatra

Bimal Mahapatra,  Professor ( Retired ) at Sambalpur University and NISER

I had met Prof. D. P. Roy three days before his sudden demise at the University of Hyderabad. I was there to attend a six day workshop and I was fortunate enough to have been able to attended Sir's lectures for four days there. The perpetual smile on his face while he taught, his warm personality, enthusiasm in his teaching and his welcoming behaviour mesmerized me and he had become an ideal personality for me in this short time. Someone I can look up to and admire. I was extremely shocked to hear of his sudden demise. Him tugging my ID, looking at it and saying 'I'll remember your name now' is his last memory I'll have. Perhaps we are the last students he taught to. May you holy soul rest in eternal peace, where ever you may be now Sir. I'll always remember you saying 'No question is ever dumb, the answer might be but never the question!'

Anshuman Baruah,  Research Scholar at Assam University, Silchar, Assam

It was a very Sad Shock for me to listen about D.P Roy sir's demise after taking a one week recent lectures on CHEP Workshop at hyderabad Sir, we were the luckiest group for being the last students of yours to interact and learn beautifully about standard model from you.The day 11th march 2017 i cannot forget when you sat near me and cleared my doubts and said.." Questions can never be dumb, answers can be". We will miss you sir. May your soul Rest in Peace.

Sonali Patnaik,  Research Scholar at ITER, SOA University, Bhubanaeswar

I am so sorry to hear the sad demise of Prof. D. P. Roy. Prof. D. P. Roy was such a wonderful person. I know him during my first G.C Meeting of IOP, that he had attended during/around December, 2002. I associated with him since then. Everyone in the office will miss his ready smile and helpful attitude around when he came to office. He was always giving compliments to every one. He made sure we knew we were appreciated and we are truly going to miss him. With my deepest and heartfelt condolences. Rajesh Mohapatra,Assistant,Director's OfficeInstitute of Physics

Rajesh Mohapatra,  Assistant at Institute of Physics

I always joke that there are five nice people in physics. He was definitely one of them.

Francis Halzen,  Gregory Breit Professor and Hilldale Professor at University of Wisconsin-Madison

This is very sad news indeed. I have many fond memories of DP, a kind-hearted man and always someone who was a pleasure to talk to. Truly one of the great ‘gentlemen’ of our subject. My heartfelt sympathies go to all his family and friends in India.

James Stirling,  Senior Professor at Imperial College London

I am very saddened to hear the passing of our friend DP. I have many fond memories of him as a friend and colleague. He was an excellent physicist, who will be remembered for his many contributions. He was always kind, warm and welcoming during my many visits to TIFR. Last time I met him, was in Warsaw in 2014. He will be very much missed.

Rabi Mohapatra,  Distinguished University Professor at University of Maryland

This is terribly sad news. What a loss. He was a wonderful person always so cheerful and full of energy & ideas.I have passed the news to Dick Roberts, who was close to DP, and he too was very sad & shocked.

A.D. Martin,  Emeritus Professor at Durham University

this is sad news indeed. I've met DP well over 30 years ago; in fact, he was the first Indian physicist I ever met (although not the first I worked with -- that was you). I'll miss him.

Manuel Drees,  Senior Professor at Bonn Theory Group

It is indeed with great shock and sorry that I received the news of DP's death. I had known DP since 1980 . When I joined TIFR in 1979 as a visiting fellow DP was away on a sabbatical or at least on a long visit outside. We must have started work on our first paper together, it was about the then heavy flavour charm, (which was much the flavour of the day for a topic to work on) produced in neutrino reactions. I still remember DP sitting in my office till late one evening as we plotted together some distribution that the model predicted and the happy smile he gave as we saw that the data were described perfectly by the model. I can not quite forget the joy on his face. It was interesting times and interesting physics. Since then the collaboration went on for 40 long years and we must have written about 25-30 papers together and many of them were luckily also well recognised. DP was a great phenomenologist. He had a `nose' for sensing interesting phenomena and imagination to create models to have a clear understanding of what was happening. His work on track isolation, tau polarisation and charged Higgs search have played an important role and inspired many a experimental investigations. DP had his hands full of interesting and current phenomenology. Even though our last published paper together dates from 2009, we of course kept on talking physics. He was very well respected by the International Collider community and I will try to share separately with you people messages that many of our common friends wrote to me after I told them about this tragic event! These show the love and affection he was able to inspire in a lot of his friends by his genuineness. I was always touched by the genuine warmth of heart he had. I recall DP again getting down from a train in Pune when it had halted where I was getting off in the middle of the night. I think we were traveling together from Bhubnaeswar where we had both gone for some meeting and he wanted to make sure that my father was there to pick me up! God knows how many years ago it was, might have been 35 odd years ago! He was a great friend and colleague! Of course he then commented about the trouble that the parents have to put up with for children to my father!! I was also touched by the battle he waged with the hospital authorities to get justice for his daughter. May his soul rest in peace.I have no words to console Monika and Kalyani. My heart goes out to them.

Rohini Godbole,  Senior Professor at CHEP, IISc, Bangalore

D.P. Roy was an internationally renowned stalwart of particle physics. This to many of us was, however, only one of of Durga-da's endearing qualities. He spearheaded the development of particle physics research and teaching in the country and especially went out of his way to encourage and help young entrants to the field. To me he was always like an affectionate elder brother. My heartfelt sympathies to his family.

Amitava Raychaudhuri,  Sir Tarak Nath Palit Professor of Physics at University of Calcutta

Professor D. P. Roy's dedication to science is exemplary. He has made tremendous and outstandingcontributions in S-Matrix Theory, QCD, Neutrino Physics, Collider Physics, and many other areas of High Energy Physics.Since the last few years he has been also contributing to popularisation of science. Through his life time efforts he has generated huge man power and human knowledge bank which will continue to benifit India for genrations to come. The vacancy created by his sad and sudden demise may be hard to fill up in future.

M. K. Parida,  Professor/Director at CETMS, Siksha 'O' Anusandhan University

It was very sad for me to learn about Durga's passing . A college classmate, a very good friend, an eminent Physicist and a very good human being , DP will be remembered fondly by all those who came to know him

S. RAI CHOUDHURY,  HONORARY PROFESSOR at IISER, BHOPAL

It was a very sad day when I learnt of DP's passing. There were too many things I would have liked to talk to him about, too many unfinished conversations....I think I first met him when he was at Riverside and then probably at TIFR. But it was a memorable time when I visited Santiniketan in 1974. He was there, having joined "Dada"(as we all called Professor Biswas in starting a particle theory group there. I still remember well, when he came to meet me at the train station on his bicycle, and later when I rode in a rikshaw with his bike accompanying us all the way to the guest-house. I had a wonderful few days there. I always enjoyed interacting with DP, never a dull moment. I spent a term at TIFR in 1983, when UA 1 announced their discovery of the W and the Z at the CERN collider. DP read the UA1 paper on the W, and raised the question about the events which had an electron and a jet. He wanted to anayse them in trrms of a possible signal for a top quark, with a mass in the range of 30'GeV, as it had the appropriate isolation and the transverse momentum. Rohini and DP did the detailed analysis, and we immediately submitted a short note to PRL and it was promptly published. Later, UA1 claimed that there were no electrons in those events, and thus our analysis was null and void! Much later, we had extensive correspondence on the analysis of neutrino oscillation data from several experiments, esp Kamland, and their interpretation. We last met in january 2015 at PRL, and we had fascinating discussion about far ranging topics. I learnt many fascinating things, not necessarily about physics, but about Gandhiji, and also about Bipin Desai......and I was hoping to continue this dialog at some point. It is a great loss, and I will miss him greatly. My condolences to his family.

Sandip Pakvasa,  Emeritus at University of Hawaii

Prof. D.P. Roy was very supportive to me when I was a postdoc at TIFR in 1984, a difficult time in my career. Despite working in an area somewhat distant from mine, he encouraged me in what I was doing and also encouraged me to broaden my knowledge of particle physics. I remain very grateful to him for both these things.

Sunil Mukhi,  Professor at IISER Pune

DP and I were colleagues at Tata Institute for thirty years. We started the WHEPP series of workshops together and have had many common collaborators including students and postdocs. Will always cherish his memory.

PROBIR ROY,  INSA SENIOR SCIENTIST at CAPSS, BOSE INSTITUTE, KOLKATA

My connection with neutrino physics stared with the review article of Prof. DP Roy.Though I have never interacted with him personally (mostly because of my shy nature to go forward and talk to the charismatic personalities) but saw him very closely giving talks and discussing physics with great intensity. From his body language I understood that he was a kind of physicist devoted to understand the ultimate truth of Nature. Its great loss for the physics community and we need more that kind of a person to take the physics forward.

Monojit Ghosh,  Post-Doc at Tokyo Metropolitan University

DP visited me at Riverside several times, and once with his family. We published 10 papers together. I last saw him in Bhubaneshwar in 2006.He was a great physicist and a great human being. It was a privilege knowing him. Ernest Ma.

Ernest Ma,  Professor at University of California, Riverside

I am shocked with DP's sudden demise, I know him since my first postdoctoral years in the UK ... He was a very good collaborator in the nineties, after I settled in Spain. More recently he spent one complete sabbatical year in our Group ... RIP DP!! we will miss you ..

Jose W F Valle,  Professor at IFIC, Valencia

Sir physics is your lifeline.you teach us how to falling love with physics and how to enjoy the romanticism of the vast world of physics.take my pranam and rest in peace .

Abhijit sanyal,  Assistant teacher at Lalgola mahesh narayan academy,west bengal