 Okay, good afternoon, everybody. So it's a pleasure to have this program today. To, it's an ICDP prize ceremony. And this is actually taking place in conjunction with our summer school in particle physics. And I'm very happy that his excellency, Ambassador Ahmad Pakachi, permanent delegate of the Islamic Republic of Iran to UNESCO is present with us. The prize this year was given to two outstanding cosmologists from Iran. Shant Bagaram, who is from Sheryl University of Technology in Tehran, Iran. And Muhammad Hussain Namjoo from the Institute for Research in Fundamental Sciences, IPM in Tehran. He's also a regular associate of ICDP. So, ICDP has a very long connection with the scientific community in Iran. And many Iranian scientists have come and contributed to ICDP's mission and have benefited from it. This ICDP prize was created in 1982 by the ICDP Scientific Council to recognize outstanding and original contributions in physics by young scientists from and working in developing countries. And awardees thus far have included many notable scientists from India, China, Brazil, Argentina, and many other countries. Together with today's two awardees, I think the total of Iranian scientists who received this prize is now goes up to five. In the past, in 2020, Dr. Mehdi Kargarian from Sharif University of Technology in Tehran received the prize. In 2013, Dr. Yasman Farzan, a woman scientist from Institute for Research and Fundamental Sciences in Tehran. And in 2007, M.M. Sheikh Jabari, again from IPM in Tehran. Let me just quickly read the citation of the prize. The two share the prize for their pioneering contributions to developing robust theoretical, computational, and statistical frameworks to compare theoretical predictions for various cosmological and astrophysical phenomena with high precision observational data. So I now request his Excellency Ambassador Ahmed Pakachi to say a few words. Mr. Director, ladies and gentlemen, scientists, researchers, I'm honored to participate in the special ceremony to award the ICTP prize, which for the fourth time is being awarded to young scientists from my country. At the outset, I wish to extend my thanks to Professor Atish Dabalkar, the Director of ICTP and his colleagues in particular the Selection Committee. Today, on behalf of Iranian government and nation, I would like to sincerely congratulate Dr. Shant Balram of Sharif University of Technology and Dr. Mohammad Hossein Namjoo of the Institute for Research in Fundamental Science. Their outstanding research and articles cover varied subjects, including dark matter and large-scale structure. Since its creation in 1945, science has been an integral part of UNESCO indeed it remains the only UN specialized agency with the mandate for science. Although the setting of standards and norms is one of the primary duties of UNESCO in the field of science, together with its related institutions, it provides scientists with an intellectual forum and engaged governments on scientific issues relating to the achievement of sustainable social, cultural and economic development. Ladies and gentlemen, science and knowledge play such a significant role in the world today that the progress of a nation is related to its collective knowledge. As we are aware, the progress of science is intrinsic to human progress. The rapid advances that have been made in science together with their technical applications are one of the most significant factors in the development of human society. All people should be able to enjoy the benefits of this advancements. Scientific development allows us to explore new paths of action in not only tackling the challenges of today but also preparing for those of tomorrow. I may say that we need not only more science but rather better and more ethical science and to meet these concerns, UNESCO created the program on ethics of science and technology. I would like to recall that the UNESCO Avicenna Prize for Ethics in Science was established in 2002 on the initiative of my country. It remains the only international prize concerned with the subject of ethics in science. We are living in the area of knowledge societies. However, scientific equitability is not always fully observed. Scientific education is essential for human development and the fulfillment of the active role that citizens may play in their country, notably in the eradication of poverty. Freedom of access to knowledge and freedom of research should accompany one another. Newly appeared information and communication technologies are highly effective in the exchange of scientific knowledge and it is essential to ensure full access to all such information in the public domain. Ladies and gentlemen, throughout history science has played a unifying role not only due to its problem solving methods and its extension in response to social needs but also through bridging divides by bringing together individuals and nations in active cooperation. That's why I'm delighted to be here today in the ICTP which is actively engaged with scientists in developing countries. It is a positive example of the international scientific cooperation which helps to foster a culture of peace. Thank you. Thank you very much, Ambassador, for those words. Now I request Professor Marko Simanovich to say a few words about the scientific background and accomplishments of the two prize winners today to set the context. Thank you. Well, thank you very much and good afternoon. Well, first of all I have to say that it is really a great honor to introduce the recipients of this year's ICTP prize. I have to say that as a PhD student here at ICTP I had the pleasure to attend several of these ceremonies in the past and every time this was a very special occasion. This award, I think perhaps more than any other, recognizes outstanding and original contribution from scientists in our field who work in developing countries and given the mission of ICTP to support science in the developing world, it has a very special place and a significance for this institution. As we heard, this award has been around for 40 years and if you look at the list of recipients, it is very impressive with names of some of the most brilliant scientists in theoretical physics. And we are very happy today to add two more of our colleagues from Iran to this list which is ever-growing and contains more and more names of brilliant researchers who do physics. So personally, being a cosmologist, I'm particularly thrilled to see that this award goes to two colleagues working in the same field. Cosmology has tremendously evolved in the last couple of decades from a more speculative to precision science and many discoveries have been made along the way, some of which had a very deep and profound impact, not only on our understanding of the history of the universe but also on neighboring fields, such as particle physics and more broadly high energy theory. Now with all these discoveries, many other puzzles emerged and given many upcoming observational campaigns that are going to deliver data with unprecedented accuracy, we can say that cosmology today is as active and promising area of research as it has ever been. Professor Bagram and Namjoo have made several contributions, as we heard in the citation, to developing robust theoretical computational statistical frameworks to compare theoretical predictions for various cosmological and natural physical phenomena with these upcoming high precision observational data. So let me say a little bit more details about their work. I would say that in particular, Professor Bagram's research recently has been mainly focused on large scale structure of the universe and late universe. He has been working on providing phenomenological models and developing new methods to test accelerated expansion of the universe. As you know, since the discovery of this accelerated expansion, the problem of cosmological constant has been one of the most intriguing and most important problems in theoretical physics. And with the new observations, any framework which allows us to test this to its limit is going to be a very, very important thing. On the other hand, Professor Namjoo has been more focusing on investigating the earliest stage of our universe, which is known as inflation, which is a big puzzle at the opposite side of the cosmic history at very early times. And he worked on several important things. In particular, some of his most important works include understanding in a little bit more detail under which conditions the so-called local mongosianities can rule out, for example, detection of local mongosianities would rule out single field inflation, which is an important class of inflationary models that we hope to test in the near future. And some other examples include the role of impact, the role in impact of massive fields during inflation to late time observables. And we are going to hear about it today. I would also like to emphasize that the two of them have collaborated on a couple of well-known and influential papers. For instance, they were studying the possibility of anisotropic clustering through the so-called anisotropic bias, which can be induced by primordial mongosianities, and also on possible asymmetry in the sky, introduced by modulation, by the best fluctuations that you observe in our universe, on the largest possible wavelengths. So to conclude, given the breadth and impact of their research, I think that this award is certainly more than well-deserved. I would like to personally congratulate you. And instead of me giving further details, I think that you're all eager to hear from the winners about their own work. And so I will stop here and invite you to present your research. Thank you. Thank you, Marco. So I would like to just add that this year's ICTP prize is, in fact, being given in the honor of Russian physicist Valeriy Rubakov for his fundamental contributions at the interface of particle physics and cosmology. In particular, Professor Rubakov wrote pioneering papers about barrier genesis, the mechanism which explains why the universe contains matter and not antimatter, non-perturbity methods, including his insightful work on monopole catalyzed proton decay, sometimes known as the, otherwise known as the Kalan Rubakov effect, and the brain world scenarios. Professor Rubakov was a dear friend of ICTP, wonderful person, and a member of the scientific council. He decided to remain in Russia after the dissolution of the Soviet Union. And he mentored a large number of students forming the Rubakov School in Moscow. He was a strong defender of academic freedom. And we will miss him because he passed away on the 18th of October, 2022. So this prize is being given in the honor of his memory. And I'm also very happy that today the prize will be given together with me by the hands of Professor Kamran Wafa. He is the holiest professor of mathematics and natural philosophy in the physics department of Harvard University. He is an Iranian-American physicist, a very distinguished string theorist. And I'm very, he not only, he has been actually a very close associate affiliate of ICTP. He has been a distinguished staff associate for many years. And he was also the member of our scientific council for many years. So I'm very happy that Kamran is here. And in fact, Kamran was here recently to inaugurate his book, which was being translated into Italian. So he has written a popular book, which you might want to read in Italian. So I now request we will proceed with the award ceremony. So I request Professor Shant Bagaram to please come forward. And now I request Professor Namjoo to come. OK, thank you. So now we proceed with the scientific presentation by the prize winners. And I just should say that following the ceremony, then you will have refreshments on the terrace. Now we go to the scientific part of it. OK, so our first speaker will be Professor Shant Bagaram. He will tell us about large-scale structure of the universe beyond the standard model of cosmology. Please. OK, good afternoon. Director of the ICTP, ladies and gentlemen, it's deeply an honor to be here and have received this prize. It's a really honor and pleasure. So I will try to, in a 30-minute talk, say what we think in these years with my supervisors and students about the cosmology. And that's the two words of the large-scale structures and beyond the standard model of the cosmology. I'm very lucky that Professor Markosomanovich gave great talks on the cosmology that makes my work very easy. So if you have questions, ask Marko in the lectures that really have the upcoming days. So, OK, I want to start the story from the 17th centuries from the Newton and the problem of the gravity and the universe. So it seems that Newton's seat in the Royal Academy of the UK and the people are coming and asking questions about, is it from 17th centuries or? So one of the guys, the Bentley, come and ask that if you apply your theory of the gravity to the universe, why doesn't sky fall over us? And what happens? And Newton didn't like these questions. And he thinks that the universe is almost homogeneous and isotropic, but that's an unknown question. So going to the 20th century, a remarkable paper by Albert Einstein that applying the gravity on the cosmology has the same question. And instead of solving the boundary problem, he said if we assume that the universe is homogeneous and isotropic, you can have a solution. There's more letters coming back between Dositer and Einstein about this. And the metric you have seen is the metric that made by Friedman, Robertson, Lometchan, Walker. And people are trying to test this idea of the homogeneity and isotropy. There are many tries from the 30s by the Shapley and the Hubble and then 50s after the World War II that the radio astronomy is developed. There's a radio telescope in Cambridge and people are trying to counter galaxies in different directions to see if this works or not. This is a modern version of looking at the universe and see if the universe is homogeneous and isotropic. This is the Sloan Digital Sky Server. They work for more than a decade and each point is a galaxy. So Marco said that if you use this assumption, you can write the cosmology very easily by the Friedman equation. And the question is how to measure the expansion rate and how much matter is in the universe. And we find that the universe is in a special case, is almost flat. This is a list from works in the 30s to recent days to just measure how much matter is in the universe. And it's 0.3 almost. It seems that the universe is flat but there is less matter. It seems that there is something ridiculous like dark energy in the universe that maybe is related to the Bentley's question that why not Sky Falls. So what we learned that the universe is very vast and very old and it's very empty. If you put the numbers and have the expansion rate, you find that there's such five protons in cubic meters. There's two great books by the Nobel Prize winners Peebles in these last two days, the Cosmos of Century and the Whole Truth that he say about the history of the cosmology and one of the greatest discoveries is the cosmic microwave background radiation, the photons that comes from the early universe. And we learned that this radiation is a black body and we know that in each centimeter cube there's 400 photons and we measured the contribution of the photons there as well. So this is the latest plot by the Planck. This is the angular power spectrum of the density of the angular power spectrum of the temperature density contrast versus the scales by Planck and you have this standard model with almost six parameters. How much baryon is in the universe? How much cold dark matter? What's the distance of us to the CMB? It measures the amount of the dark energy and three parameters that is related to the early universe. So it seems that it happens a revolution in the 1998 to 2003. We have this cosmological standard cosmological model on the CDM and you can teach the standard cosmology in a semester and you need an initial conditions that Professor Namjoo will talk about it and you can make the universe. So summing up, what we know about the universe is that the universe is all very big. It means that there is dark energy. It says that the essential force in the universe is the gravity and there is dark matter that makes the structures and the initial condition of the universe is very simple. It means the perturbations are almost Gaussian, scale invariant and isotropic and you have two assumptions that the GR is the right theory of the gravity and you have this Einstein principle of cosmology that the universe is homogeneous and isotropic. It's a great model but we don't know of 95% of it and we don't know how is the physics of the early universe. That's a great area of research because almost you know nothing about it. Okay, so what will be our plan to study the universe? Instead of asking fundamental question we can go and check how the different constitutes of this model can be changed. For example, asking if lambda, cosmological constant is the reason of the expanding universe is called dark matter right or not and the initial condition GR and Einstein cosmological principle that will be the plan. So this is my supervisor, professor Sourabh Ravra I have much depth to him. It's two decades ago when I was an undergrad student and he teach us that the structure formation is important and we are doing it for two decades. The idea is the gravitational instability is important because it makes the structures from the initial condition to the late times. So why is structure formation important? Because if you go and measure the distribution of the structures in the linear regime you can find out that there's a differential equation that the Hubble constant goes through it the pressure and how the gravity acts and there's great progress in linear perturbation theory. You have the matter power spectrum even you saw the bump of the bionic acoustic oscillation the physics of the early universe maps in the late time. So that's great but when you look at the observation or the simulations of the cosmology you see that the cosmology is not linear almost in the smaller scales and there's a cosmic web there's halos, there's filaments, there are voids and you have to look at the cosmos in the nonlinear regimes. If you ask an astronomer that what we can observe maybe I put a wrong thing here, okay thank you. So if you ask an astronomer you will say that observable is the luminosity function of the galaxies and then you have to relate it to the number density of the dark matter halos. So what we try to do thanks to the ICTP programs because I was visiting here as a junior and I worked with the great scientist Professor Ravi Ches and he introduced us about this idea of the musing of the pressure and the shecter and the works that is done by the other colleagues and the S is the Ches and Torman and the other guys. So the great idea is that instead of doing simulation you can look at the initial condition of the universe where the perturbations are almost linear and Gaussian and ask that if you evolve them how many how much of the structures will be made in the universe. So it's a good idea to make simulation but it's costly and you have different models to check and even in a specific model if you have changed the parameters you have to do the simulation again. So it's great to have some semi-analytical ideas to go with this data. So what's the pressure or exclusion set theory idea? The idea is very nice and easy. It says that the x-axis is the scale in the universe so you choose the biggest scale you can imagine and you count the structures in it and you calculate the density contrast. The y-axis is density contrast. And you start to decrease the scales to have the smaller and smaller scales so you have some trajectory for each point in the universe. So there's a critical density in the linear theory, delta C, if one of the trajectories touches this barrier it seems that there's a structure in that scale and it's important to find the first crossing. So people, the bound k-ser and f-stashu and col they use a very specific smoothing window function k-space because they know how these trajectories can be solved, they are Markov and they look at the Chandrasekhar papers in 40s and they have the solutions. So what we did with our colleagues is to make this process non-Markov if you choose any smoothing function which is more physical like the Gaussian or top hat in the real space and you have the trajectories in the... in trajectories and you can count the number of the crossing and you have the number of the structures in the universe. This works is lately done by Farnik and Mamadreza who are post-docs in Yale and Heiderberg now and we have both approximations and numerical solution for this problem. So the other thing that I did with my PhD students, Mamad, is that we asked that if we can find the number of the filaments in the universe and it's related to the saddle points in the distribution of the early universe and this is, we put the name of the excursion set theory of the saddle points. So we want to push it further by Hamid as we know the gravitational astronomy is on its way and it's important to have the merger history of the structures or progenitor history of the structures. So this excursion set theory can shows... can calculate in the first approximation the number of the conditional crossings. So you can move the barrier upper to count the number of the structures in the higher rate shift. It's trivial because you need more density contrast if you want to make structures in higher rate shifts and we try to make this idea as a test for checking the models. Sorry I'm passing this through to slide quickly to show what the problems are there and then I can answer the questions in the break if there are some. So the other works that we promote by my PhD students and master's students is looking to the one point statistics. The idea is that if you're going to the cosmic web in simulation or in observation you can stand on a specific point and ask what is the number of the nearest neighbor. This specific point can be a random point if we call it the spherical collapse, spherical contact sorry or you can go and sit on a dark matter halo or a galaxy it names not nearest number density. So it's related to correlation function that cosmologists can do the work with it by the nominal paper by Wight in the 1979 and we plot, we calculate this for different mass scales different galaxies and different red shapes and it seems that it could be a novel probe for checking the cosmologists beyond the standard model. For example you can add neutrinos and see how this j function which is the spherical contact and near distribution can change. It seems that it is related to the minimum mass but in the range of 0 to 1 it's not changed. Okay I pass through this going back to another idea is the cold dark matter problem or not. One of the ways to look at this problem I want to ask Marko if there's five minutes remaining just told me that. There's much more, okay. And even if you are tired you can say I can pause. So the other ideas is about the cold dark matter so it's important to know if the cold dark matter is the real dark matter model. One of the ideas is go to the smaller and smaller scales people are doing many simulations because the smallest mass of the dark matter can say that this dark matter is cold or it's warm or it's hot. There are some problems the people are talking it's about more than a decade that like missing satellite problems or too big to fail problem and a community says that maybe the baryonic physics is the solution but again you have to answer this question. One of the ideas that we developed by my supervisors Professor Rahvar and my postdoc mentor Professor Afshordi is the idea of the transit weak cleansing. The idea of transit weak cleansing is that if you have a source and there's many of these dark matter substructure passing through the line of sight you can find a lensing effect which is a transit which is have a time dependence so you can calculate the power spectrum of the change of the lensing. So you can ask that what are the sources that you can find because the sources in astronomy they have their intrinsic fluctuation if you have this idea if you're going to look at the strong gravitational lensing sources you can subtract the intrinsic change in light and find this transit weak lensing. However we can put an upper limit about the distribution of these dark matter structures. So another work is recently our people are talking about this fuzzy dark matter models that make this solitonic course with our joint PhD students now Dr. Maliki we go through the pattern of the lensing in the colliding cores of the dark matter if there is some quantum mechanical effects in the dark matter. So we want to relate these two ideas of beyond cold dark matter and simple initial conditions this is one of the other pillars of the cosmology and this is the work by my former student Dr. Kameli that to solution for the too big to fail problem or missing satellite problem maybe it's not the modified cold dark matter or maybe it's not the bionic physics but modified initial condition. People are talking that you can change the power spectrum in the small scales and we choose a very phenomenological model we put a bump in the power spectrum in the smaller scales and we ask how it will be changed the number density of the structures it seems that we have more structures like Milky Way but we have less in the smaller dwarf galaxies we check that this result are consistent with the paradigm and alpha test and it could be an idea if someone could simulate this model so this is important because people are recently talking about the primordial black holes as the source of the gravitational wave and if you need to make primordial black holes in the paradigm of the inflation you need to have an excess in the power in the smaller scale so maybe these two ideas can be related so we try with one of our colleagues to find the number density of the primordial black holes in the context of the exclusion set theory what we did is that if this is the shrinking cobble radius the smaller scales go first out of the horizon and come first so we have to do this mechanism of exclusion set theory from the right to the left the other works that they mainly contribute with Professor Namjoo and our mentor in the IPM Dr. Feroz Jai is the ideas related to the late time universe and the early universe such as the CMB lensing I'm not go through this the last almost last part of the talk is about the lambda or GR so recently it's five or six years we are talking about the H0 tension that if you measure the Hubble constant from the nearby supernovies is four or five much different with the one you measure from the cosmic microwave background as a one parameter of the lambda CDM so we come up with one of my best friends Dr. Khosravi in Shahid Beshti and Professor Afshordi a model known over lambda CDM that it shows a change in the gravity model and in the Hubble parameter but still not a very successful model because you have to make the prediction for the structure formation as well so we have a chance that Professor Mashun one of the guys that works with the wheeler in the 17s he comes to our university and give lectures and we learn a lot from him and he give the stories about the D-key and the wheeler and the pebbles and he works on the non-local gravity and we try to make a cosmological model from the non-local gravity the idea is brilliant so the general relativity has a couple of assumptions like equivalence principle the Lorentz invariance and locality the locality is that any observer in the university is accelerated point by point is locality like a Minkowski observer so if you have an acceleration in the universe acceleration is something absolute so it introduce a specific length and if you have some averaging process like the waves you have to take the non-local effects there's a great book by him Non-local Gravity by Afshord and people are talking about this idea from the Anishtain to the Weyl and the Minkowski and etc so in order to introduce the non-locality to the gravity we have to go to the teleparallel equivalent of the GR which is make the gravity very similar to the electrodynamics so instead of working with the metric you work with the tetrods and instead of the curvature you have distortion and we know how to make a theory non-local in electrodynamics by introducing this epsilon and mu which are the permeability of the matter if you apply an electric and magnetic field to the matter we did the same procedure with the gravity and we look at the local limit of it so if you look at the homogeneous and isotropic cosmology it's only one function of s of t so you have ability to fit with the data and solve the Hubble tension and we are very interested to learn about this more the last thing it's about the Anishtain principle cosmology the other works that is done with Dr. Mohaye in ERP that asking if really we have we are living in a homogeneous universe so I have a couple of thank you slides this is a slides from summer school in cosmology in 2008 I want to thank Professor Kreminelli for hosting me during the junior associate years and organizing these wonderful events it has a very deep impact in this year Professor Rubakov talked to us about the dark matter I have his notes and I bring it with myself it really I'm saying that it's had a great impact for a first year PhD student and the other thing which is not scientific but cultural is the Marikuri library because in the last four years I have the responsibility of the libraries in Sharif University and the Marikuri library is very inspiring and we try to make the libraries like the ones that are in the ICTP the physics department library is in the name of the Abdu Salam and the central library is trying to be some place like the library in the ICTP at last but now this I want to thank you my brilliant students that I learned very much from them they are bright and I'm very happy and I know that they make the future of Iran in the scientific very much bright and great and no need to say in a particle physics conference that the cosmology is very important and there's many discoveries that happen in the cosmology thank you very much this is the Foko Pendoliom I can host you in a conference of particle physics or cosmology there thank you very much thank you for the very nice talk and perhaps we can ask if there are some questions we have time for a couple of questions thank you for the nice talk and during your talk you explained that the small bump in the power spectrum can fit to the limon alpha forest and I wonder the shape of that bump actually important to fit the data or is it completely irrelevant no it's important so it's like a Gaussian bump that it has two variables the variance and the amplitude and you have to put constraint on both of these parameters otherwise you cannot pass the limon alpha forest thank you any other question so I have a question the excursion said mother that you mentioned so you said that it's not it was originally assumed to be Markovian and you considered the deviation from Markovianity can you explain how good of an assumption it is for it to be Markovian or is it something when is it Markovian when it is not very nice question so if you have these trajectories and you choose a top hat filter in the case space then your trajectories will be Markovian and you know the solution but it seems not a real model because if you Fourier transform the k-sharp to the real space it's like something have negative smoothing function and positives otherwise if you go to the real space and make a Gaussian smoothing function or top hat in the real space so you are not Markovian anymore Any other questions? I do not see any so maybe I would like to invite Professor Namjoo to present his own work on probing the primordial universe using heavy particles Hello everyone thank you very much for the prize and for this opportunity Shant sorry maybe I should be more official Dr. Bakram ended by acknowledgement I am going to start by acknowledgement so I should thank my wife and also my parents who have been so patient and very supportive during this whole years of education and hard working and I am also grateful to all my collaborators who helped me a lot to be able to contribute to science okay so this pointer is not working I need to keep rest so I am going to tell you about how possibly we can probe the primordial universe the tool that I am going to use is the heavy particles I am going to tell you what heaviness would mean here it has some technical meaning my talk would be based on these papers in collaboration with these nice guys and this is the outline of my talk I am very briefly going to talk about inflation, introduce inflation to non cosmologists and very briefly alternatives to inflation then I will tell you how massive fields or massive particles are going to help to probe the primordial universe and this comes under the name of under the name of primordial standard clock so again I will tell you why we have chosen this terminology the massive fields at the early universe are called primordial standard clock it becomes clear later on why this is so and then I will tell you about the properties of the signals that we expect to get out of these primordial standard clocks so inflation what is inflation inflation is an accelerated expansion of the universe at very early times when the universe was very young perhaps a tiny fraction of second old the inflation itself had happened for again a tiny fraction of second but there is a dramatic change to the universe as a result of inflation inflation becomes much much bigger after inflation compared to what it was before inflation ok so why do we need inflation we seem to need inflation because what we observe today has some particular properties this is an example if you look at the universe in different directions you see that the universe is almost at larger scale is almost isotropic meaning that for example if you count the number of galaxies looking at that direction and compared to the number of galaxies in that direction you get more or less the same thing the same number so this means that the universe is isotropic and if you add to it the Copernican principle which states that we are not in a particular position in the universe you can conclude that the universe is also homogeneous so the universe is both isotropic at largest scales another observable that we can look at and get basically the same conclusion is the cosmic microwave background which is a microwave light that is coming to us from distant places this is basically the oldest light and the most distant places that we can even in principle observe this is the cnb map what is actually showing you is the perturbations the anisotropy on the cosmic microwave background but these perturbations are pretty small so at leading order we can conclude that again this cosmic microwave background radiation is isotropic so what is the problem here is the problem if you want to have such a homogeneous and isotropic universe you need to have a very particular initial conditions for your universe a small change in the initial conditions would lead to a very different universe compared to what we see today so it seems that without inflation we are going to have a problem in the initial conditions the initial conditions of the universe need to be finely tuned but this is the work of inflation that washes out basically the sensitivity of observable universe to the initial conditions so in a large fraction of the space of all possible initial conditions what you get at late times as long as inflation was there would be basically the same and this was the main reason for the growth in 1981 to introduce inflation so how inflation can happen this is a kind of weird behavior of the universe like it's an accelerated universe with positive acceleration and for this thing to be realized you need to have a kind of classical scalar field at least one classical scalar field that is rolling on top of an almost flat potential then the inflationary phase can be realized so yeah this is this is the inflationary scenario it has been very successful it can disentangle the observable universe from the initial conditions sort of but this is not the only success of inflation this classical scalar field that is rolling on this potential has also some quantum fluctuations the quantum effects are always there it's not avoidable and this is pretty helpful because also provides us a nice mechanism for generating the fluctuations that we see at very large scales including the fluctuations that we see in the CMB for example right so what is the mechanism these quantum fluctuations are there during inflation and these fluctuations are straight out from small scales to very large scales and the small scale fluctuations become large scale fluctuations during inflation and then these large scale fluctuations can be considered as primordial seeds for the fluctuations that we see and observe at late times so this is a nice link between what we learn from the quantum field theory to what we observe at large scales so these fluctuations will be a bit technical but don't panic I'm not going to go through the details just showing you a flavor of what kind of theoretical framework we are dealing with so we need to do cosmological perturbation theory as I've told you the two leading order the universe is homogeneous and isotropic so the line element for that universe is pretty simple is also simple and this is just a scale factor that quantifies the size of the universe as the universe expands this A of T the so-called scale factor becomes bigger but now we want to add fluctuations, small fluctuations so the metric would change it would change in different ways including that kind of change we introduce a new parameter zeta which is called curvature perturbation up to some gauge freedom that I'm going to ignore in this talk and then since you are dealing with Einstein's equations you need to also perturb the other side of Einstein's equation which is the matter sector so the matter sector should also be perturbed the scalar field the perturbations of the scalar field and basically you can derive equations of motion for these fluctuations or write down the action for them in particular for zeta for the curvature perturbation and this I'm going to work with this parameter zeta because it is directly related to the fluctuations that we are going to see at later times zeta as a random variable or more precisely as a quantum field you can calculate different correlation functions including this two-point correlation function or power spectrum or you can go to higher orders and calculate the higher order correlators like the three-point correlation function and so on what are the predictions of inflation as long as the inflation in model remains sufficiently simple here is the prediction of the inflationary scenario it predicts that the fluctuations have to be almost scalar invariant and almost Gaussian and this prediction works remarkable well in describing our universe this is the this is the most recent data the power spectrum the two-point correlation function of fluctuations on the cosmic microwave background and this red line is the theoretical prediction this theoretical prediction contains a lot of information a lot of physics including the predictions of inflation it's not just inflation but inflation is also included and you see that they match pretty well the data and the theory match pretty well so this is the success of inflation and perhaps that's the reason that most people believe on inflation but pros and cons come together there are some objections to inflation as well here is a list of objections to inflation it's a complete list but just to mention a couple of them people claim that the simplest model models of inflation has been disfavored by most recent data thousands of models of inflation are there why? because the physics governing inflation is unknown we don't know what is the potential under which the scalar field is evolving or whether we have one scalar field or more than one scalar field the particle physics theory of the inflationary universe is unknown some models of inflation lead to the multiverse and the major problem is there it's not even sometimes clear whether the fine tuning problem is solved if inflation had occurred then yes we are going to solve the fine tuning problem in cosmology but the question is that do we need another fine tuning for inflation itself to happen or not some people claim that the inflationary scenario is not falsifiable the singularity problem is still there the initial singularity cannot be resolved by inflation so I don't necessarily buy these arguments but the point is that some people based on these arguments against inflation decided to think about alternatives and they actually came up with some interesting ideas one example is a matter contraction scenario in which you have temporality contracting universe at early stages and if such a contracting universe is filled with a non-relativistic matter you can conclude that the predictions for perturbations for the fluctuations is almost the same as the predictions of an inflationary universe and there are other scenarios as well another example they are not as beautiful as inflation but still there are some proposers and as long as the observation is concerned they are almost indistinguishable so now I'm getting closer to the main topic of my talk here is two fundamental questions that I want to ask how can I probe inflation as I have told you the physics governing inflation on now so how can I probe directly the physics behind inflation and even more important or more fundamental is inflation really the true story of the universe or we should think of alternatives so I'm going to skip that slide because it's a bit technical just to mention what is the question here I'm going to tell you that I can't probe the primordial universe using the massive particles but the question is do we expect them to be there and the answer is yes we do expect them to be there there are several theories that predict that they should be there and if we assume that massive particles are present at the early universe we can use them to probe the primordial universe so how these particles are going to generate some signal for us it's pretty simple I can just tell you about it without showing equations so it's based on the resonance mechanism so this is the massive particle and massive here means that the mass should be larger than the Hubble parameter larger than the expansion rate of the universe at early times then I'm going to call such a particle as massive and if the mass is sufficiently large this massive field is going to oscillate with frequency mass and this is a universal thing it is independent of the evolution of the universe that's why we call it standard clock primordial standard clock it ticks like a pendulum and it is standard in the sense that the frequency of the oscillation is independent of the evolution of the universe on the other hand you have another thing which is let's say Zeta the curvature perturbation which is also oscillating at early stages of its evolution but the frequency of this oscillation is quite different from the previous oscillation and this oscillation has a time dependent frequency at some certain point these two frequencies would match and then you get a resonance of course this resonance is not a disaster it's a good thing because you're going to observe such a resonance effect at late times so what kind oh okay yeah let me tell you about two types of standard clock that we should deal with since this massive field has to oscillate there are two ways to excite the massive field so that it starts oscillating maybe the simplest way to think about this is the classical way in which case you have a sharp phase transition which triggers the massive field and it starts oscillating around the minimum of the potential but if this phase transition did not happen we still have quantum fluctuations right quantum fluctuations are unavoidable they are there and these excitations of the quantum field can also play the role of standard clock so we have two types of standard clock and they have basically different signals so we can distinguish between them so a bit of technicality here again just to quantify how the universe behaves at early times I'm gonna assume that the scale factor behaves like t to the power of p and for different values of p I have different behaviors of the universe if p is larger than 1 I have inflation if p is 2 third I have matter contraction if p is something between 0 and 1 I have slow contraction etc so what I'm looking for is a signal that is p dependent so it encodes the information about the time evolution of the universe at early times so if I show you a signal that is p dependent then I'm done I have a prediction it depends on the time evolution of the universe at early times and this is the signal that you can basically calculate using the idea of the resonance mechanism you see that this is a signal in the Fourier space so a signal is a function of k you have an overall amplitude right which can be scale dependent but besides that you have an oscillator factor this is the important factor here and you see that the frequency of oscillation is changing with scale and how it changes with scale is p dependent the change in the frequency of these oscillations would be p dependent so it can if you can observe such a signal then you can distinguish between inflation and alternative scenarios you can discover how the universe was evolving at early times this is just a visualization of the same signal and you see that you see that they are different for different scenarios right the signal is different for different scenarios there are two ways to think about the massive fields at early universe one is the primordial standard clock that I've just told you the other is that if you for some reason convince that you know what was the evolution of the universe then the question is that do you care about these massive fields to be present at early universe or not the answer is yes you should care about that because even if you don't care about this p dependence here you should still care about the physics of early universe right so because this frequency also depends on mass of the particles so you can do if you can observe such a signal at late times you can basically do the spectroscopy of the early universe this is the so called cosmological particle collider okay so how we are going to observe them is it actually an observable thing or not as I've told you at leading order the current data is telling us that the primordial fluctuations should be almost scale invariant okay whereas what I've shown you as the signal is changing with scale so it is not scale invariant this means that we should look at the higher order corrections to our first order theory and we should look at the more precise data to be able to observe such an oscillatory signal but already in the Planck data there are some interesting candidates it's not that significant because as you see the error bars are pretty large here but we can hope that in the near future when we get better data we might be able to either put strong constraints on such signals or even discover them and in particular the near future observations of large scale structures by Euclid and LST is very important for that particular purpose we have shown that you can put much stronger constraints than Planck you can put much stronger constraints than Planck using the LST or Euclid data these are kind of forecasting right we still don't have the actual data yet but the difference between Planck and Euclid or LST you see that the contours are much smaller for LST and Euclid as compared with Planck data this is the concern that you can in principle put on the such kind of oscillatory feature on the power spectrum just a few words about the things that I'm currently working on it seems that besides the observational constraints that we can put on the different scenarios of the early universe there are also some theoretical I'm almost done there are also some theoretical constraints that in particular alternative scenarios not inflation alternative scenarios should satisfy if they want to work and be consistent with observations these are coming these new constraints that we are working on are coming from the existence of massive fields at early stages of the universe okay we have seen that there are some instabilities and deviations from perturbativity of the theory as a result of the existence of these massive particles if you consider for example matter contraction scenario this is still a work in progress okay in this talk I was trying to advocate the possibility of distinguishing between inflation and alternative to inflation using massive particles and I have argued that the massive particles are also pretty important to discover the physics governing the early universe's dynamics if you believe that inflation was the true story you can still use the massive particles to discover the physics behind inflation and the future prospect of discovery of these particular signals this oscillatory signal is very promising thank you very much for this nice talk I will ask again if there are some questions thank you for your great speech professor as a non cosmological physicist I have an ambiguous issue here you mentioned the standard clocks we have two standard clocks in quantum and classical and they measure something is this thing are comparable I mean when you measure something with classical clock is it comparable with that in the quantum clock or not comparable I mean are they in the same space or scale or not completely different okay if the question is that are they distinguishable or not yes they are distinguishable they can appear at the same scale depending on some details of the the model of the universe but they are very distinguishable because for example for the classical standard clock you need to have a phase transition and the phase transition itself would also have some non-trivial signal that you can in principle observe whereas for the quantum version you don't have such a signal the other thing is that I didn't tell you much about it but if you look at the three-point correlation function of the fluctuations because of the conservation of momentum you have at this triangle right of three momenta and for the classical standard clock if you change the size of this triangle you see these oscillatory features whereas for the quantum standard clock you need to change the shape of this triangle then again you see some oscillatory features but this is as a result of the quantum standard clock so they are very different they basically generate very different signal thank you any other question thank you for the nice talk so usually these cosmo collider signals with heavy particles have some exponential suppression that's right the signal you were talking about first of all is this the power spectrum or the three-point function it depends for the quantum standard clock it is hard to see in the power spectrum unless if you have alternative scenarios it's not going to work for inflation so for the quantum standard clock you expect to see these effects at higher order correlation functions including the three-point correlation function but this is not the case for the classical standard clock it can also appear with large amplitudes at the power spectrum but you are right for the quantum version of the standard clock you have this Boltzmann suppression but then this means that how large the coupling is what is the model that you are considering so the amplitude of the signal is model dependent you need to be lucky enough so that these oscillates signals are large enough so you can observe them in the future any other questions? thank you for the talk I wanted to ask about the phase transition that you just mentioned in regards to standard classical clocks what kind of observable would that produce like gravitational waves or other cosmological observables and if there are prospects for detection of these signals you are talking about the phase transition that you need for the classical standard clock this is again about the evolution of the early universe and since we don't know the physics of the early universe we can just imagine what possibly can happen this is one way for this phase transition to be realized at the early universe this is a let's assume that it is an inflationary universe right and this is the scalar field that is rolling on a potential this is the the field space a two-dimensional field space so it is not just a scalar field we have two scalar fields driving inflation and initially you have at the ridge of this potential but you can fall down to the value of the potential then it is a kind of phase transition and this phase transition is something that I was talking about right and this phase transition would trigger the massive field to oscillate and this is the trajectory of the field in the field space you see that there are some oscillations here any other question hello professor so thank you for hearing your talk my question is about like since I am working in extra-dimensional stuff so if ever there is an extra dimension predicted by string theory or some minimal extension of the standard model and you talk about massive particles like for example the right-handed neutrinos or the actions dark photons that could propagate to an extra dimension so my question is like I would like to hear your opinion the dynamic of the extra dimension the size of the extra dimension at the early stage of the universe could you comment about this one thank you I am not sure I got the question I am not expert on the extra dimension stuff but the thing is that the theory is that predict extra dimension would also this is the usual thing that also predicts existence of massive fields if you are living on a lower-dimensional space-time so yeah this physics would also tell you that you should expect to have massive fields at early universe and whether okay one question is that is this distinguishable from a theory which has no extra dimensions but has some additional particles massive particles my guess is that they are not distinguishable but again I am not expert on that are there any other questions okay if not let us thank the speaker again