DEPARTMENT OF PHYSICS

IIT BOMBAY

RESEARCH AREAS OFFERED FOR PHD CANDIDATES

DECEMBER 2021

List of open PhD positions (Dec 2021)

❖ Condensed Matter Physics (Experiments) (4 positions) ➢ Prof. K. G. Suresh

➢ Prof. Subhabrata Dhar

➢ Prof. Maniraj Mahalingam

➢ Prof. S. Mahapatra

❖ Condensed Matter Physics (Theory) (1-2 positions)

➢ Prof. Himadri Sekhar Dhar

❖ Nuclear and High Energy Physics (Theory and Experiments) (4 positions)

➢ Prof. Asmita Mukherjee

➢ Prof. Vikram Rentala

➢ Prof. Basanta Kumar Nandi

➢ Prof. Sadhana Dash

❖ Optics (Theory and Experiments) (3 positions)

➢ Prof. Anshuman Kumar

➢ Prof. Dinesh Kabra

❖ Soft Matter and Biophysics (Theory and Experiments) (5 positions)

➢ Prof. Nitin Kumar

➢ Prof. Amitabha Nandi

➢ Prof. Raghunath Chelakkot

➢ Prof. Punit Paramananda

➢ Prof. Mithun Kumar Mitra

K. G. Suresh Field of research: Magnetism and Spintronics, Topological Matter, Magnetic Skyrmions

My main research work for the last few years is on identifying novel and potential materials for multifunctional applications including spintroniocs. We mainly focus on Heusler alloys family for this purpose. The work involves various routine characterization techniques and also some state of the art and sophisticated facilities such as synchrotron radiation. We have been successful in identifying some potential materials for half metallic ferromagnets, spin gapless semiconductors, bipolar magnetic semiconductors and spin semimetals. This has been possible by combining the experimental results with the theoretical studies. There are many more systems to be explored from this angle. Recently, we have also started focussing on topological semimetals, which are also known as novel quantum materials, which are characterized by the difference between the properties in the bulk and the surface. These have different surface states induced by the topology of the bulk band structure. Topological Dirac or Weyl semimetals show linear dispersion around points known as the Dirac or Weyl points. One of the families from which one can look for such materials is again the Heusler alloys.

Proposed Topic of work

This proposal is to carry out further investigations with the aim of identifying novel materials in general and more so from the point of view of topological effects. The plan is to identify novel and potential Heusler alloys and a few similar systems which have the properties of different types of topological materials. The proposed work involves the identification of such classes of materials on the basis of insights already obtained from the experimental and theoretical studies. The materials will be prepared in polycrystalline and single crystalline (wherever required) forms. All the required structural, magnetic and transport characterisation will be carried out. Theoretically simulated band structure will be verified with experimental probes such as de Haas - van Alphen studies and angle resolved photo-emission (ARPES) studies. By combining the experimental and theoretical findings, we will be able to propose novel and potential materials from this family that will exhibit topological features suitable for different applications. Certain specific measurements will be carried out on selected materials to bring out some interesting aspects such as chiral anomaly, spin Hall effects, anomalous thermoelectric effects etc.

References:

1. Equiatomic Heusler alloys: a materials perspective for spintronic applications, Lakhan

Bainsla and K. G. Suresh, Appl. Phys. Reviews 3 (2016) 031101 2. Spin Gapless Semiconductors: Fundamentals and Applied Aspects - (Invited

Perspective Article) Deepika Rani, Lakhan Bainsla, Aftab Alam and K. G. Suresh J. Appl. Phys. 128 (2020) 220902

3. Bipolar magnetic semiconducting behaviour in VNbRuAl, Jadupati Nag, Deepika Rani, Jiban Kangsabanik, Durgesh Singh, R. Venkatesh, P. D. Babu, K. G. Suresh, and Aftab Alam, Phys. Rev B 104 (2021) 134406

4. Realizing Topological States in Type-II Dirac Semimetal PdTe2: An Angle Resolved Photoemission and Quantum Oscillations Study, Jadupati Nag, Anshu Kataria, R. P. Singh, Soma Banik, Aftab Alam and K. G. Suresh, Bul. of Mat Sci. (2021) (accepted)

Subhabrata Dhar [Experimental Condensed Matter Physics] Our Research Activities Growth: epitaxial layers (GaN, InN, ZnO, In2O3, NiO) and heterostructures, 2D semiconductors (MoS2), semiconductor nanostructures

Device Fabrication: e-beam/photo-lithography

Studies: (i) Influence of surface on the properties of low dimensional systems (ii) Shape engineering of nanostructures for novel applications

(iii) Electronics/optoelectronics based on low dimensional systems (iv) Optical and magnetic properties of defects (v) Magnetic semiconductors (vi) 2D semiconductors (vii) Excitons, interfacial excitons

Characterization Techniques used: High resolution XRD, TEM, SEM, AFM, XPS, Raman

Facilities developed in the lab: (i) various electrical and optical spectroscopy at variable temperatures (down to 1.5K) (ii) Magneto-optical studies (down to 1.5K, magnetic field ±8T) (iii) Transport, magneto transport (down to 1.5K, magnetic field ±8T)

People: About 10 members, mostly PhD students, couple of postdocs and a few master project students

Research topic to be offered for PhD Understanding semiconductors embedded with ferromagnetic nanoparticles

Though, the formation of ferromagnetic clusters in various semiconductor matrices has been reported, the effect of these nanomagnets on the spin property of the semiconductor band structure is not yet been fully understood. Recently, we have achieved the growth of NiO epitaxial layers embedded with crystallographically oriented Ni clusters on c-sapphire substrates. This has given us opportunity to explore these questions further.

Prof. Maniraj Mahalingam

Condensed Matter Physics - Experiment

Current activity of the group member is focused on experimental investigation of material's electronic band structure using state of the art ultrahigh vacuum based surface science techniques, such as photoemission, inverse photoemission, scanning tunneling microscopy and spectroscopy, and electron diffraction. In a simplified version, these technique provide information about all quantum numbers and structure of the materials. Output of these measurements are widely employed to understand the physical properties such as optical, magnetic, and transport properties.

As a material system of choice, focus are on two dimensional materials with wide range of properties, suitable for technological application and fundamental research.

One of the topic is new family of graphene analogy materials, widely known as X-ene. Key activities are to grow them in-situ, and characterize using mentioned techniques to establish its predicted physical properties and support with theory.

Another topic of interest is oxide based quasicrystal. Key activities are designing/identifying a new composition out of wide range of available bulk oxide materials, and its in-situ growth and characterization.

Mostly likely activity at the beginning includes designing and constructions of components needed for the above research topics. Additionally, implementing and establishing the electron diffraction and spectroscopy methods are expected to be a primary activity in the laboratory.

Suddhasatta Mahapatra Field of Research: Experimental Condensed Matter Research Group: Silicon Quantum Computing (Q-Si lab) One of the promising approaches of building a practical quantum computer makes use of electron spins in silicon to realize the quantum bits, or qubits. The architecture makes use of devices and processes which are well-established and optimized for the semiconductor electronics industry. Hence, this practical implementation of a quantum computing is attracting world-wide research attention. Our group is engaged in fabrication and benchmarking of fundamental quantum operations of a few-qubit spin quantum computer, as a part of a national mission for development of quantum technologies. Making use of the state-of-the-art cleanroom facilities at IIT Bombay, and the cryogenic electronic transport measurement facility being set up in the Physics Department (Q-Si Lab), our group envisages to meet the global milestones in the next 5 years. We are glad to invite you to join this exciting journey. As a prospective member of the Q-Si lab, we expect you to join us with a strong understanding of quantum mechanics, solid state physics, electronics, semiconductor devices and scientific programming. Any prior courses taken on Quantum Information Processing is certainly a bonus, but not mandatory. We also expect you to be self-driven and keen on learning new techniques and topics, and develop skills of using sophisticated tools and processes.

Faculty name : Asmita Mukherjee Area of research : Theoretical high energy physics

Brief description of project : I work in the field of QCD. Mostly I am interested in the tomography of the nucleon, a hot topic in recent days . A three dimensional structure of the proton in terms of quarks and gluons can be obtained by bombarding high energy proton beams or electron beam with a proton beam. Such experiments are being done at the Large Hadron Collider at CERN, also at Jefferson lab, USA. The upcoming electron ion collider(EIC) at Brookhaven National Lab will extensively investigate these questions. My group at present is involved in theoretical calculations that will play a vital role in the analysis of the data from these colliders. Mostly I am interested the spin-dependent processes, when either one of the colliding beams is polarized. The cross section depends on the polarization, and one can measure the single spin asymmetry, that often results in an asymmetry in the azimuthal angle of the observed final state particle. These asymmetries probe the transverse momentum distributions of quarks and gluons in the proton, for example the Sivers function or the Boer-Mulders function. My group is involved in providing theoretical estimates of these spin asymmetries that will be measured at the future EIC.

Prof. Basanta Kumar Nandi High Energy Nuclear Physics – Experiment

The experimental high energy nuclear physics group is involved in the ALICE experiment at CERN, Geneva. ALICE experiment is dedicated to the search for Quark Gluon Plasma which was formed at the early stage of the Universe. This experiment is currently taking data for different collision systems and at different energies. The group is actively involved in the data analysis of the ALICE data. Currently, physics interest of the group is in the areas of correlations and fluctuations, HBT and heavy flavor measurements.

ALICE is going to have the Forward Electromagnetic Calorimeter (FOCAL) to address the physics at low-x region. India is also planning to join this international effort by contributing to the detector hardware and software development. The FOCAL is a sampling calorimeter consisting of Tungsten(W) and Si. India is planning to contribute part of the Si detector. This is now the R&D phase of the Si sensor. In India BEL will be our partner to design and deliver the Si sensors. It will be fully tested in the laboratory across India and finally shipped to CERN, Geneva for final installation in the ALICE experiment.

The selected candidate will be working on the testing of the Si detectors and physics capability of FOCAL using the Monte Carlo generated data. At the same time the candidate will be involved in the correlation and fluctuation analysis of the pp collisions data at √𝑠 = 14 TeV for identified particles using the number correlator (𝑅2) and momentum correlator (𝑃2). All these analysis are being carried out in the ROOT environment using C++ language. The candidate is expected to learn C++ and ROOT, if (s)he is not familiar with it.

Prof. Sadhana Dash Experimental High Energy Physics Proton-proton (p-p) and Heavy Ion collisions at LHC using ALICE Detector The physics of heavy ion collisions and quark gluon plasma has been at the frontier of the physics topics at the LHC energies. The availability of heavy -ion and p-p data from ALICE experiment at LHC has generated a lot of theoretical and phenomenological activities all over. ALICE (A large Ion Collider Experiment) at LHC, CERN is a specific multipurpose experiment to study heavy ion as well as the p-p collisions at LHC energies. The recent observation of experimental signatures in p-p collisions which are reminiscent of QGP has created a lot of interest in medium effects in elementary collisions as well. The selected student will be involved in data analysis pertaining to heavy ion and pp collisions. She/He will also be involved in some software and hardware development activities involved in such experiments. Currently, we have three interesting problems in our group which require immediate attention and investigation. Our group is taking part in data analysis related to resonance particles, heavy flavor analysis and particle correlations. Apart from real data analysis, the student will also be involved in some phenomenological studies related to heavy-ion and p-p physics .

Prof. Nitin Kumar Soft Matter Physics (Experiment)

Experiments with smart programmable robots to study non-

equilibrium dynamics of living systems Have you ever wondered why a herd of sheep, flying birds, or fish in the ocean, all move in an ordered fashion? In all these and many more such examples, there are either large-scale collective dynamics or the display of global orientational order, or both. The question arises, what causes this state? What are the physical laws governing such dynamics and phases? The common feature in all these systems is that all the individual units, known as active particles are living and operating out of the equilibrium. A collection of such particles is known as Active Matter. Such active systems show rich physical and mechanical properties which have no analogue in equilibrium physics.

To answer these questions, we build smart, centimeters-long programmable robots which are capable of sensing neighbours and obstacles. This YouTube video should help you get a feel of the kind of experiments that you will do in my lab (https://youtu.be/xK54Bu9HFRw). We program these robots to mimic various active matter systems found in nature. Since these systems operate far away from equilibrium, we also aim to address fundamental problems in non-equilibrium statistical physics. I seek Ph.D. students in this newly established experimental Active and Soft Matter group in the Physics department.

Please visit my home page for more details. Feel free to get in touch with me. My email address is nkumar@iitb.ac.in

Timeline: 4-5 years

Goals and Outcome: By the end of a successful Ph.D. program in our group, you will become an expert in the field of study with the ability to work independently, navigate a new field of research, work in a group in a collaborative environment, and learn to communicate scientific ideas with others in an effective manner.

PI: Prof. Mithun Kumar Mitra Research Group: Theoretical Biophysics Group Research Field: Soft Matter Physics - Theory

Website: http://home.phy.iitb.ac.in/~mithun/ Email: mkmitra@iitb.ac.in

Research: My group uses theoretical and numerical techniques from equilibrium and non-equilibrium statistical mechanics, soft matter physics and dynamical systems to study the physics of living systems. Some of the main themes of our research include -

(i) The physics of development in early embryos - What are the physical principles that control the development process in early embryos? How does the complex organization of living systems arise from simple physical laws? (ii) Spatial organization of the genome - What physical forces control the organization of DNA inside a nucleus, and how does this structural organization impact the functioning of chromosomes? (iii) Intracellular transport by molecular motors - How does stuff (proteins/vesicles/...) get transported inside cells? How do non-equilibrium processes controlled by the consumption of ATP ensure reliable deterministic transport?

Please see my group website for further details. Vacancies: ONE (1)

Interested candidates may contact me by email prior to the admissions process. Requirements: We are looking for a strongly motivated PhD student who wishes to work on the exciting new frontier of the physics of living systems. The interested student should have

❏ A strong background/interest in theoretical physics, specifically statistical physics (equilibrium statistical physics and preferably non-nonequilibrium physics and stochastic processes).

❏ Strong coding skills - Our research involves simulations as well as theory. You should be able to demonstrate strong coding skills (in any language of your choice). Previous demonstrable coding experience is desirable.

❏ Broadly, you should have an interest in biology and living systems. Previous exposure is NOT required, however you should be excited about learning about such systems. Some of our research involves working in close collaboration with experimental biology colleagues, both in IIT Bombay and elsewhere in India.

Further reading: https://physics.aps.org/articles/v12/2

Selected recent publications from group:

1. The Accidental Ally: Nucleosome Barriers Can Accelerate Cohesin-Mediated Loop Formation in Chromatin 2. Dynein catch bond as a mediator of codependent bidirectional cellular transport 3. Cyto-architecture constrains the spread of photoactivated tubulin in the syncytial Drosophila embryo

Prof. Punit P.

Research activities of Experimental nonlinear dynamics Laboratory

Our lab is currently involved in a total of five experimental systems where we study various phenomena of Non-Linear dynamics. The first one of them is the Mercury Beating Heart (MBH) system which is a chemo-mechanical oscillator. In this we study a wide range of phenomena which includes synchronization of an ensemble of oscillators, quorum sensing and cessation of oscillations. We also have a system in which we study the interaction of noise with the non-linear dynamics, which is the etching of Silicon wafer in presence of Hydrofluoric acid. An electrochemical setup which exhibits relaxation oscillations is currently being employed to study the phenomenon of Stochastic Resonance. Another interesting non-linear system we are exploring is the oscillations of candle flames. Finally, the latest project that our lab has undertaken is the study of Brain dynamics when subjected to different types of photic and/or auditory stimuli.

However, for this cycle I would like to add one student to my group to work in the following project.

Short project Description

The student would be expected to investigate,both experimentally and numerically, the various facets of collective and emergent phenomena in active particles. This would involve studying both the isolated and the ensemble dynamics of these motile particles from the perspective of statistical mechanics as well as nonlinear dynamics.

Prof. Raghunath Chelakkot

Field of Research: Soft matter (Theory)

Topic: Dynamical ordering in non-equilibrium active-matter. Nature is abundant of physical systems that are driven out of equilibrium. Most of such

systems include many particles, following some general physical rules and energy pumped

in externally, which often create mechanical driving.

We are interested in studying a new type of non-equilibrium systems, called active matter.

There are plenty of examples for active matter all around us; flocking birds, animal herds,

swarming bacteria, several components in biological cells are a few examples. The major

difference in such systems is that energy is pumped internally at an individual level, proving

additional freedom for the constituent elements. Recent studies have shown that these

systems show rich and complex ordered patterns, and many properties are similar to

classical phase transitions.

To study the system using two approaches,

1. Agent-based modelling - here, we model individual elements using stochastic

differential equations (Langevin equations with appropriate noise). We study the

large-scale collective behaviour emerging as a result of various types of interactions

between the elements. Computer simulations are used for such studies. These

simulation often include long-ranged hydrodynamic interactions derived from low

Reynolds number fluid mechanics.

2. Mean-field approach - From the nature of order and symmetry of the system, we

construct non-equilibrium free-energy functional and obtain the time-evolution of

relevant order-parameters. (Example, Toner-Tu equations, ϕ − 4 scalar field theory,

etc.)

Both these approaches are complimentary for a given system. These models reveal new

types of physical systems that are previously unexplored. Further, these studies help us to

have a better understanding of many elusive complexities in nature.

Biological Physics/Softmatter Physics (Theory)

Principal Investigator: Amitabha Nandi Department of Physics, Indian Institute of Technology Bombay, Mumbai

Biological Physics

Biological physics involves the study of physical principles that govern living matter at various spatial scales. There has been a growing interest during the last two decades in studying living matter using quantitative approaches. Significant advancements in experimental techniques have led to a better understanding of mechanical and dynamical processes inside cells and tissues, thus opening up a box full of exciting and challenging questions for theoretical physicists, mathemati- cians, and engineers.

Here are two articles which you may read to get an overall idea:

(1) Life is Physics , and (2) Quantitative cell biology: the essential role oftheory

of collective cellular flows and the formation of morphogen (chemical) gradients using theoretical and computational techniques.

2. Study of transport inside cells

Intracellular transport is a complex non-equilibrium process that allows reliable delivery of material, thus enabling the proper functioning of a living cell. Cargoes inside cells are transported both passively by diffusional mechanisms, as well as actively, due to non-equilibrium forces generated locally within the cells. While diffusional transport helps the cargo probe, the local environment, active transport, on the other hand, is helpful to traverse large distances in a directed way. Our goal is to study the mechanisms of active transport in various scenarios by developing theoretical models that take the non-equilibrium forces into account.

Research in our group

We use theoretical and computational techniques to study various dynamic processes inside a living cell and their implications to key functions of the cell

3. Study of cytoskeletal and tissue dynamics in the hydrodynamic limit

and to morphogenesis, namely, the process of devel- The formalism to describe the cytoskele- opment of an organism. To do this, we use methods from non-equilibrium statistical mechanics, nonlin- ear dynamics, and soft-matter physics. Our research involves collaboration with cell and developmental biologists.

Research projects

1. Physics of morphogenesis

During the course of development of an organism, tissues are dynamically remodeled due to me- chanical forces generated within the cells, causing biological functions like cellular rearrangements, cell division, and apoptosis (cell death). This further drives spatial organization at larger length- scales, causing the formation of complex biological structures, like the different organs with highly specialized functions. We are interested in how forces of non-equilibrium origin are generated and

ton as an out-of-equilibrium continuum fluid has been very successful in describing and understand- ing several biological functions of a living cell. We are interested to use and improvise this theory to study complex dynamic behaviors at cellular and tissue-scale. Examples include the study of cell division and the emergence of spatio-temporal instabilities in cells and tissues.

Here are few relevant references: [1], [2], [3], [4], [5],

Requirement

1. Strong background in classical and statistical mechanics, and mathematical physics,

2. Good programming skills, and,

how they redistribute various chemical agents or morphogens spatially, leading to the formation of spatial structures. This involves theoretical study

3. Strongly motivated to work at the physics- biology interface.

active gel

Prof. Anshuman Kumar Optics and photonics (experiment and theory)

Laboratory of Optics of Quantum Materials (LOQM) Website: http://loqm.tech

General introduction to our group: Principal Investigator: Prof. Anshuman Kumar Physics Department (1st floor), IIT Bombay Laboratory of Optics of Quantum Materials (LOQM) -- http://loqm.tech

In simple words, the main focus of our current research is exploring the fundamental physics and building unique technological solutions using natural and artificial two dimensional materials such as graphene, MoS2 and metasurfaces. Such materials display many unconventional optical properties which are not found in usual three dimensional materials. We are interested in applications of our work in energy harvesting, sensing, sub-wavelength imaging and optical circuitry.

Here are some candid photos of us working in the lab:

In recent years, we have made a number of important contributions to the field, which were widely covered in the popular press:

PhD topic for Optics and Photonics group at LOQM Principal investigator:

● Prof. Anshuman Kumar, Physics Project: Title: Valleytronics in two dimensional semiconductors via metamaterials Subgroup to apply: Photonics Experiment or Theory Positions available: 2

Project abstract: Recently, atomically thin transition metal dichalcogenides (TMDCs) of the form MX2 (M = Mo,W; X = S, Se, Te) have emerged as a new class of semiconductor materials for both fundamental physics exploration in two-dimensional systems and device applications These monolayer semiconductors are manifested by a direct band gap between the extrema of valence and conduction bands residing at the energy-degenerate K and K’ points of the Brillouin zone (called valleys). Harnessing this valley degree of freedom (analogous to spin up/down degree of freedom in spintronics) in TMDC monolayers for quantum information processing requires coherent manipulation of excitons in the K and K’ valleys.

Metamaterials are artificial assemblies of nanoscale elements which act as an effective media allowing us to mold the light field in any desired way. Metamaterials derive their properties not from the properties of the base materials, but from their newly designed structures. Such systems have immense applications in the areas of invisibility cloaking and diffraction limit breaking superlenses and lead to counterintuitive phenomena such as negative refraction.

In order to manipulate the valley degree of freedom in TMDCs, in this project we will explore ways to engineer the excitonic emission in the two valleys of TMDCs by tuning the local optical density of states via metamaterials. Being at the intersection of these fields, this project would enable you to learn cutting edge techniques in lasers, nanophotonics, nanofabrication and condensed matter physics.

The project has two parts, one theoretical/computational and another experimental. The theoretical part would involve two kinds of calculations: 1) optical susceptibility of 2D semiconductor heterostructures and 2) optical density of states in metamaterials using fully numerical and semi-analytical techniques being developed by our group. Experimental side would involve nanofabrication of metamaterials via electron beam lithography and photolithography, deposition of 2D materials and optical characterization of these coupled modes. Depending on the interest of the student one can switch to a completely theoretical or completely experimental project. There is scope for pursuing new directions as per student interest within the general field of nano-optics of 2D materials.

(You may contact the PI for further details about this project)

Hybrid Optoelectronic Device Laboratory Group

Head: Prof. Dinesh Kabra

Research Thrusts: From Fundamental Physics to Devices

Our research is focussed on the optical and electronic properties of molecular and nanoscale semiconductor systems. In particular we are interested in emergent phenomena in molecular and hybrid systems, i.e. phenomena that occur in ensembles but not in isolated molecules or semiconductor particles. In the past few years we have uncovered evidence that such phenomena underlie the efficient operation of a range of optoelectronic devices based on molecular and perovskite semiconductors. We are inventor of Blue

Spectroscopy Solar cells Transistors LEDs

LEDs using Perovskite semiconductors and highly efficient green OLEDs. Solar cells fabricated in our group has got efficiency numbers crossing internationally published papers. We believe in transferring our fundamental knowledge into device related intellectual properties and then research papers.

Our present group size is

Assistant Professor: 1

Post Doc: 2, PhD students: 7, Master Student: 2, Under-graduate student: 3

Information on publication side: http://scholar.google.co.in/citations?user=33jcxp0AAAAJ&hl=en

Skills required: Sincerity, dedication and hard working candidates with knowledge of general physics and interest in semiconductor physics and optics.

Faculty: Himadri Shekhar Dhar, Assistant Professor Research Interests: Our main research interest lies at the interface of quantum information theory, quantum optics and many-body physics. In particular, we explore the properties of complex quantum systems using both analytical and computational tools, to not only obtain novel insight into our physical world, but also to design and control devices that can be harnessed in modern quantum information and computation technology.

Openings: 1-2 doctoral scholars.

Potential project(s): Manipulation of spin ensembles for computation and error-correction

We are interested in harnessing the dynamics of realistic spin ensemble systems interacting with quantum cavities to develop new approaches to understand effects such as spin squeezing [1], and design macroscopic fault tolerant computation models [2] or quantum error correction codes [3].

[1] Reservoir-engineered spin squeezing: macroscopic even-odd effects and hybrid-systems implementations, arXiv:2104.10363. [2] Blueprint for a Scalable Photonic Fault-Tolerant Quantum Computer, Quantum 5, 392 (2021). [3] Robust Encoding of a Qubit in a Molecule, Phys. Rev. X 10, 031050 (2020).

The Hierarchy Problem and the Higgs boson - with Prof Vikram Rentala Monday, November 22, 2021 10:56 PM

The Higgs boson discovered at the Large Hadron Collider (LHC) in 2012 was the final missing piece of the Standard Model of particle physics. However, the discovery raises a lot more questions than it answers. Why is the Higgs boson mass of 125 GeV so much smaller than the Planck scale of 10^19 GeV, where quantum gravity effects are expected to be strong? In general, within the framework of effective quantum field theory, it is expected that the Higgs boson receives large corrections to its mass from new physics which is inaccessible to us at current collider experiments. The difference between the observed (tiny) Higgs mass and the large value expected from quantum corrections is called the hierarchy problem. This problem has driven much of the frontier of particle physics phenomenology for the last 40 years.

Exotic theories such as supersymmetry, extra dimensions, technicolor etc., attempt to solve the hierarchy problem, but they also predict that signatures of new physics must be around the corner, waiting to be discovered either at the LHC or near future experiments.

Students who take up this project will be able to explore ideas to solve the hierarchy problem, increase our understanding of the nature of the Higgs boson, build models of SUSY and extra dimensions, and explore alternatives to the framework of local effective quantum field theory.

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