169 results on '"Debasish Borah"'
Search Results
52. Dark Matter and Leptogenesis in Minimal $$U(1)_{B-L}$$ Model with Nonminimal Quartic Inflation
- Author
-
Suruj Jyoti Das, Debasish Borah, and Abhijit Kumar Saha
- Published
- 2022
- Full Text
- View/download PDF
53. Freeze-in Dark Matter via Light Dirac Neutrino Portal
- Author
-
Anirban Biswas, Debasish Borah, Nayan Das, and Dibyendu Nanda
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,FOS: Physical sciences ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We propose a scenario where dark matter (DM) can be generated non-thermally due to the presence of a light Dirac neutrino portal between the standard model (SM) and dark sector particles. The SM is minimally extended by three right handed neutrinos ($\nu_R$), a Dirac fermion DM candidate ($\psi$) and a complex scalar ($\phi$), transforming non-trivially under an unbroken $\mathbb{Z}_4$ symmetry while being singlets under the SM gauge group. While DM and $\nu_R$ couplings are considered to be tiny in order to be in the non-thermal or freeze-in regime, $\phi$ can be produced either thermally or non-thermally depending upon the strength of its Higgs portal coupling. We consider both these possibilities and find out the resulting DM abundance via freeze-in mechanism to constrain the model parameters in the light of Planck 2018 data. Since the interactions producing DM also produces relativistic $\nu_R$, we check the enhanced contribution to the effective relativistic degrees of freedom $\Delta {\rm N}_{\rm eff}$ in view of existing bounds as well as future sensitivities. We also check the stringent constraints on free-streaming length of such freeze-in DM from structure formation requirements. Such constraints can rule out DM mass all the way up to $\mathcal{O}(100 \, {\rm keV})$ keeping the $\Delta {\rm N}_{\rm eff} \leq \mathcal{O}(10^{-3})$, out of reach from near future experiments. Possible extensions of this minimal model can lead to observable $\Delta {\rm N}_{\rm eff}$ which can be probed at next generation experiments., Comment: 48 pages, 10 captioned figures, matches version accepted for publication in Phys. Rev. D more...
- Published
- 2022
- Full Text
- View/download PDF
54. TeV scale resonant leptogenesis with Lμ−Lτ gauge symmetry in light of the muon g−2
- Author
-
Arnab Dasgupta, Debasish Borah, and Devabrat Mahanta
- Subjects
Physics ,Particle physics ,Gauge boson ,Muon ,Leptogenesis ,High Energy Physics::Phenomenology ,Higgs boson ,High Energy Physics::Experiment ,Neutrino ,Standard Model ,Gauge symmetry ,Lepton - Abstract
Motivated by the growing evidence for the possible lepton flavor universality violation after the first results from Fermilab's muon $g\ensuremath{-}2$ measurement, we revisit one of the most widely studied anomaly free extensions of the standard model namely, gauged ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ model, to find a common explanation for muon $g\ensuremath{-}2$ as well as baryon asymmetry of the universe via leptogenesis. The minimal setup allows TeV scale resonant leptogenesis satisfying light neutrino data while the existence of light ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ gauge boson affects the scale of leptogenesis as the right handed neutrinos are charged under it. For ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ gauge boson mass at GeV scale or above, the muon $g\ensuremath{-}2$ favored parameter space is already ruled out by other experimental data while bringing down its mass to sub-GeV regime leads to vanishing lepton asymmetry due to highly restrictive structures of lepton mass matrices at the scale of leptogenesis. Extending the minimal model with two additional Higgs doublets can lead to a scenario consistent with successful resonant leptogenesis and muon $g\ensuremath{-}2$ while satisfying all relevant experimental data. more...
- Published
- 2021
- Full Text
- View/download PDF
55. Muon (g − 2) and XENON1T excess with boosted dark matter in Lμ − Lτ model
- Author
-
Narendra Sahu, Debasish Borah, Manoranjan Dutta, and Satyabrata Mahapatra
- Subjects
Physics ,Nuclear and High Energy Physics ,Gauge boson ,Particle physics ,Annihilation ,Muon ,QC1-999 ,Dark matter ,Fermion ,Anomaly (physics) ,Lepton ,Standard Model - Abstract
Motivated by the growing evidence for lepton flavour universality violation after the first results from Fermilab's muon (g−2) measurement, we revisit one of the most widely studied anomaly free extensions of the standard model namely, gauged Lμ−Lτ model, known to be providing a natural explanation for muon (g−2). We also incorporate the presence of dark matter (DM) in this model in order to explain the recently reported electron recoil excess by the XENON1T collaboration. We show that the same neutral gauge boson responsible for generating the required muon (g−2) can also mediate interactions between electron and dark fermions boosted by dark matter annihilation. The required DM annihilation rate into dark fermion require a hybrid setup of thermal and non-thermal mechanisms to generate DM relic density. The tightly constrained parameter space from all requirements remains sensitive to ongoing and near future experiments, keeping the scenario very predictive. more...
- Published
- 2021
56. Gravitational waves from a dark U(1)D phase transition in light of NANOGrav 12.5 yr data
- Author
-
Arnab Dasgupta, Sin Kyu Kang, and Debasish Borah
- Subjects
Physics ,Particle physics ,Seesaw molecular geometry ,High Energy Physics::Phenomenology ,Dark matter ,Scalar (mathematics) ,Electroweak scale ,Neutrino ,Type (model theory) ,Vector boson ,Standard Model - Abstract
We study a possibility of a strong first-order phase transition taking place below the electroweak scale in the context of a $U(1{)}_{D}$ gauge extension of the standard model. As pointed out recently by the NANOGrav Collaboration, gravitational waves from such a phase transition with appropriate strength and nucleation temperature can explain their 12.5 yr data. We first find the parameter space of this minimal model consistent with NANOGrav findings by considering only a complex singlet scalar and $U(1{)}_{D}$ vector boson. The existence of a singlet fermion charged under $U(1{)}_{D}$ can give rise to dark matter in this model, preferably of nonthermal type, while incorporating additional fields can also generate light neutrino masses through typical low-scale seesaw mechanisms like a radiative or inverse seesaw. more...
- Published
- 2021
- Full Text
- View/download PDF
57. Refinement of simple solar tent dryer for production of quality dried fish
- Author
-
Parag Saikia, Kapil Deb Nath, and Debasish Borah
- Subjects
Dried fish ,Simple (abstract algebra) ,media_common.quotation_subject ,Production (economics) ,Environmental science ,Quality (business) ,Pulp and paper industry ,media_common - Published
- 2020
- Full Text
- View/download PDF
58. Doubling farmers income through adoption of integrated farming system- a case study
- Author
-
Pradip Rajbangshi, Pabitra Kr Saharia, Debasish Borah, and Kapil Deb Nath
- Subjects
Agricultural science ,Integrated farming ,Business ,System a - Published
- 2020
- Full Text
- View/download PDF
59. Self-interacting inelastic dark matter in the light of XENON1T excess
- Author
-
Manoranjan Dutta, Satyabrata Mahapatra, Debasish Borah, and Narendra Sahu
- Subjects
Physics ,Gauge boson ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Cold dark matter ,010308 nuclear & particles physics ,Dark matter ,Scalar (mathematics) ,FOS: Physical sciences ,01 natural sciences ,High Energy Physics - Experiment ,Standard Model ,Hidden sector ,High Energy Physics - Phenomenology ,High Energy Physics - Experiment (hep-ex) ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,010306 general physics ,Phenomenology (particle physics) ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Majorana fermion - Abstract
We propose a self-interacting inelastic dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. Two quasi-degenerate Majorana fermion DM interact within themselves via a light hidden sector massive gauge boson and with the standard model particles via gauge kinetic mixing. We also consider an additional long-lived singlet scalar which helps in realising correct dark matter relic abundance via a hybrid setup comprising of both freeze-in and freeze-out mechanisms. While being consistent with the required DM phenomenology along with sufficient self-interactions to address the small scale issues of cold dark matter, the model with GeV scale DM can explain the XENON1T excess via inelastic down scattering of heavier DM component into the lighter one. All these requirements leave a very tiny parameter space keeping the model very predictive for near future experiments., Comment: 34 pages, 14 figures, version accepted for publication in PRD more...
- Published
- 2021
- Full Text
- View/download PDF
60. Non-thermal leptogenesis and UV freeze-in of dark matter: impact of inflationary reheating
- Author
-
Rishav Roshan, Debasish Borah, and Basabendu Barman
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Dark matter ,FOS: Physical sciences ,Inflaton ,Coupling (probability) ,Standard Model ,High Energy Physics - Phenomenology ,Baryon asymmetry ,High Energy Physics - Phenomenology (hep-ph) ,Leptogenesis ,Production (computer science) ,Neutrino ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We study a minimal scenario to realize non-thermal leptogenesis and UV freeze-in of a Standard Model (SM) gauge singlet fermionic dark matter (DM) simultaneously, with inflaton field playing a non-trivial role in their yields. The renormalizable interactions are restricted to the SM fields, two right handed neutrinos (RHN) and inflaton coupling exclusively to the RHNs, while the DM couples to both the SM and the RHNs only via operators of dimension $d>4$. Considering two separate cases of $d=\{5,6\}$, we show that for $d=5$, inflaton decay into RHNs followed by their subsequent decay into SM particles lead to both reheating as well as DM production from the SM bath. This requires a cut-off scale as large as $\Lambda\sim 10^{17}~\rm GeV$ depending on the DM mass. On the other hand, for $d=6$, DM production happens directly from scattering of RHNs (for $\Lambda\gtrsim 10^{14}~\rm GeV$) that results in a very non-trivial evolution of the DM yield. In both these cases, it is possible to explain the observed baryon asymmetry through successful non-thermal leptogenesis via the decay of the RHNs, together with the PLANCK observed relic density of the DM via pure UV freeze-in mechanism. Taking into account both instantaneous as well as non-instantaneous reheating separately, we constrain the parameter space of this minimal scenario from relevant phenomenological requirements including sub-eV scale active neutrino masses and their mixing., Comment: 48 pages, 9 figures, Accepted in PRD more...
- Published
- 2021
61. Fermion Singlet Dark Matter in Scotogenic B-L Model
- Author
-
Debasish Borah, Nimmala Narendra, Dibyendu Nanda, and Narendra Sahu
- Subjects
Physics ,Particle physics ,High Energy Physics::Phenomenology ,Dark matter ,Scalar (mathematics) ,Fermion ,Neutrino ,Neutrino oscillation ,Symmetry (physics) ,Lepton ,Standard Model - Abstract
We study the possibility of right-handed neutrino Dark Matter (DM) in a gauged \(U(1)_{B-L} \times Z_{2}\) extension of the Standard Model (SM) which is augmented by an additional scalar doublet, being odd under \(Z_{2}\) symmetry to explain the scotogenic radiative neutrino masses. Due to lepton interactions, the right-handed neutrino DM can have additional channels apart from the usual annihilations through scalar and gauge portals, which give rise to much more allowed mass of DM from relic abundance criteria. This enlarged parameter space is consistent with the neutrino oscillation and relic density of DM. Due to the possibility of the \(Z_{2}\) odd scalar doublet being the next to lightest stable particle (NLSP), one can have interesting signatures like displaced vertex or disappearing charged tracks provided that the mass splitting between DM and NLSP is small. more...
- Published
- 2021
- Full Text
- View/download PDF
62. A first order dark $SU(2)_D$ phase transition with vector dark matter in the light of NANOGrav 12.5 yr data
- Author
-
Debasish Borah, Arnab Dasgupta, and Sin Kyu Kang
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We study a dark $SU(2)_D$ gauge extension of the standard model (SM) with the possibility of a strong first order phase transition (FOPT) taking place below the electroweak scale in the light of NANOGrav 12.5 yr data. As pointed out recently by the NANOGrav collaboration, gravitational waves (GW) from such a FOPT with appropriate strength and nucleation temperature can explain their 12.5 yr data. We impose a classical conformal invariance on the scalar potential of $SU(2)_D$ sector involving only a complex scalar doublet with negligible couplings with the SM Higgs. While a FOPT at sub-GeV temperatures can give rise to stochastic GW around nano-Hz frequencies being in agreement with NANOGrav findings, the $SU(2)_D$ vector bosons which acquire masses as a result of the FOPT in dark sector, can also serve as dark matter (DM) in the universe. The relic abundance of such vector DM can be generated in a non-thermal manner from the SM bath via scalar portal mixing. We also discuss future sensitivity of gravitational wave experiments to the model parameter space., Comment: 10 pages, 6 captioned figures. accepted for publication in JCAP. arXiv admin note: substantial text overlap with arXiv:2105.01007 more...
- Published
- 2021
- Full Text
- View/download PDF
63. Common Framework for Inflation, Dark Matter, Baryogenesis and Neutrino Masses in the Scotogenic Model
- Author
-
Debasish Borah, P. S. Bhupal Dev, and Abhass Kumar
- Subjects
Inflation (cosmology) ,Physics ,Baryogenesis ,General Relativity and Quantum Cosmology ,Particle physics ,Leptogenesis ,High Energy Physics::Phenomenology ,Dark matter ,Higgs boson ,High Energy Physics::Experiment ,Neutrino ,Lepton ,Vacuum expectation value - Abstract
We consider the scotogenic model involving an extra inert scalar doublet and three SM-singlet fermions, all under an additional \(\mathbb {Z}_2\) symmetry, to explain inflation, dark matter, baryogenesis and neutrino masses simultaneously. The inert scalar doublet is coupled to gravity non-minimally and after a conformal transformation forms the inflation in the early Universe.Later its lightest scalar component freezes-out to give the dark matter candidate. Baryogenesis happens via leptogenesis by the decay of \(N_1\) to SM leptons and the inert doublet particles. The \(N_i\)’s and the inert doublet combine with the SM neutrinos and the Higgs vacuum expectation value (vev) to generate neutrino masses at the loop level. We show that with the scotogenic model, we get a very economical model for combining inflation with dark matter, baryogenesis and neutrino masses. more...
- Published
- 2021
- Full Text
- View/download PDF
64. Anomalous Magnetic Moment and Higgs Coupling of the Muon in a Sequential U(1) Gauge Model with Dark Matter
- Author
-
Rathin Adhikari, Imtiyaz Ahmad Bhat, Debasish Borah, Ernest Ma, and Dibyendu Nanda
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment (hep-ex) ,High Energy Physics - Phenomenology (hep-ph) ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Physics::Instrumentation and Detectors ,High Energy Physics::Lattice ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,High Energy Physics::Experiment ,Astrophysics - Cosmology and Nongalactic Astrophysics ,High Energy Physics - Experiment - Abstract
We study an Abelian gauge extension of the standard model with fermion families having non-universal gauge charges. The gauge charges and scalar content are chosen in such an anomaly-free way that only the third generation fermions receive Dirac masses via renormalisable couplings with the Higgs boson. Incorporating additional vector like fermions and scalars with appropriate $U(1)$ charges can lead to radiative Dirac masses of first two generations with neutral fermions going in the loop being dark matter candidates. Focusing on radiative muon mass, we constrain the model from the requirement of satisfying muon mass, recently measured muon anomalous magnetic moment by the E989 experiment at Fermilab along with other experimental bounds including the large hadron collider (LHC) limits. The anomalous Higgs coupling to muon is constrained from the LHC measurements of Higgs to dimuon decay. The singlet fermion dark matter phenomenology is discussed showing the importance of both annihilation and coannihilation effects. Incorporating all bounds lead to a constrained parameter space which can be probed at different experiments., Comment: 26 pages, 7 captioned figures, accepted for publication in Phys. Rev. D more...
- Published
- 2021
- Full Text
- View/download PDF
65. Inelastic fermion dark matter origin of XENON1T excess with muon (g − 2) and light neutrino mass
- Author
-
Dibyendu Nanda, Satyabrata Mahapatra, Debasish Borah, and Narendra Sahu
- Subjects
Nuclear and High Energy Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Dark matter ,FOS: Physical sciences ,Electron ,01 natural sciences ,Computer Science::Digital Libraries ,Standard Model ,High Energy Physics - Experiment ,symbols.namesake ,High Energy Physics - Experiment (hep-ex) ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,010306 general physics ,Physics ,Muon ,010308 nuclear & particles physics ,High Energy Physics::Phenomenology ,Fermion ,lcsh:QC1-999 ,MAJORANA ,High Energy Physics - Phenomenology ,Dirac fermion ,symbols ,Neutrino ,lcsh:Physics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Motivated by the recently reported excess in electron recoil events by the XENON1T collaboration, we propose an inelastic fermion dark matter (DM) scenario within the framework of a gauged $L_{\mu}-L_{\tau}$ extension of the standard model which can also accommodate tiny neutrino masses as well as anomalous muon magnetic moment $(g-2)_{\mu}$. A Dirac fermion DM, naturally stabilised due to its chosen gauge charge, is split into two pseudo-Dirac mass eigenstates due to Majorana mass term induced by singlet scalar which also takes part in generating right handed neutrino masses responsible for type I seesaw origin of light neutrino masses. The inelastic down scattering of heavier DM component can give rise to the XENON1T excess for keV scale mass splitting with lighter DM component. We fit our model with XENON1T data and also find the final parameter space by using bounds from $(g-2)_{\mu}$, DM relic, lifetime of heavier DM, inelastic DM-electron scattering rate, neutrino trident production rate as well as other flavour physics, astrophysical and cosmological observations. A tiny parameter space consistent with all these bounds and requirements will face further scrutiny in near future experiments operating at different frontiers., Comment: Version 3: 8 pages, 3 figures; matches version accepted for publication in Phys. Lett. B more...
- Published
- 2020
66. Gravitational origin of dark matter and Majorana neutrino mass with non-minimal quartic inflation
- Author
-
Abhijit Kumar Saha, Suruj Jyoti Das, and Debasish Borah
- Subjects
Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,media_common.quotation_subject ,Dark matter ,FOS: Physical sciences ,General Relativity and Quantum Cosmology (gr-qc) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,General Relativity and Quantum Cosmology ,symbols.namesake ,High Energy Physics - Phenomenology (hep-ph) ,Planck ,media_common ,Minimal coupling ,Inflation (cosmology) ,Physics ,High Energy Physics::Phenomenology ,Astronomy and Astrophysics ,Inflaton ,Universe ,MAJORANA ,High Energy Physics - Phenomenology ,Space and Planetary Science ,symbols ,Neutrino ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We propose a minimal framework to address successful quartic inflation, dark matter (DM) production in the early universe and non-vanishing tiny Majorana neutrino mass from a common gravitational origin point of view. In this setup, the quartic inflation is revived successfully via non-minimal coupling of inflaton to gravity while the production of DM takes place from purely gravitational effects through a misalignment mechanism. The generation of light Majorana neutrino mass is aided by explicit breaking of global lepton number symmetry through Planck suppressed operators involving non-zero vacuum expectation value (VEV) of the inflaton field. We present a detailed study of the DM yield in presence of non-minimal inflation, considering both the metric and the Palatini formalisms of gravity wherever appropriate. We reach at some interesting and different results in the DM sector compared to the earlier works in the similar direction with minimal inflationary background. Restricting to the light DM regime ($\mathcal{O}(1)$ keV- $\mathcal{O}(100)$ MeV) where classical production is expected to dominate over the quantum production, we numerically predict the DM mass by varying the DM quartic and non-minimal coupling, to be consistent with relic density requirements. We also obtain some non-trivial dependence of DM phenomenology on some of the relevant parameters of the inflation sector {\it e.g.} non minimal coupling and inflaton VEV. To explore the dependence on inflationary parameters further, we also estimate the DM relic using the same mechanism for two other inflationary models consistent with latest data and observe that one of these models predicts different range of DM mass upto hundreds of TeV., 34 pages, 12 captioned figures, matches version accepted for publication in Physics of the Dark Universe more...
- Published
- 2020
67. Sub-TeV singlet scalar dark matter and electroweak vacuum stability with vectorlike fermions
- Author
-
Rishav Roshan, Debasish Borah, and Arunansu Sil
- Subjects
Quark ,Physics ,Particle physics ,010308 nuclear & particles physics ,Dark matter ,Scalar (mathematics) ,Electroweak interaction ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Fermion ,01 natural sciences ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,High Energy Physics::Experiment ,Singlet state ,Neutrino ,010306 general physics ,Lepton - Abstract
We study a scalar singlet dark matter (DM) having mass in sub-TeV regime by extending the minimal scalar singlet DM setup by additional vector like fermions. While the minimal scalar singlet DM satisfies the relic and direct detection constraints for mass beyond TeV only, presence of its portal coupling with vector like fermions opens up additional co-annihilation channels. These vector like fermions also help in achieving electroweak vacuum stability all the way up to Planck scale. We find that for one generation of vector like quarks consisting of a $SU(2)_L$ doublet and a singlet, scalar singlet DM with mass a few hundred GeV can indeed satisfy relic, direct detection and other relevant constraints while also making the electroweak vacuum absolutely stable. The same can be achieved by introducing vector like leptons too, but with three generations. While the model with vector like quarks is minimal, the three generations of vector like lepton doublet and neutral singlet can also give rise to light neutrino mass at one loop level., Comment: 38 pages, 16 figures and 3 tables, The accepted version in PRD more...
- Published
- 2020
68. Recent Advances in Material Synthesis
- Author
-
Anuradha Roy Choudhury, Debasish Borah, Alok Roy, Bimal Bhushan Chakraborty, and Nirmalendu Das
- Subjects
Nanotechnology ,Material synthesis - Abstract
The area of material synthesis is a rapidly developing field of research which enables scientists not only to discover the high yield, cost effective or environment friendly methods , but also providing them some new opportunities to work in the world of nano science. The green approaches in one hand are the alternative way to synthesize the material by minimizing the wastes as well as toxic substances, on the other hand the synthesis of nanoparticles has gained tremendous attention owing to their many fold applications in various fields. This book is designed to give the readers an outline of some of the very special topics from current prospective of different approaches for material synthesis. more...
- Published
- 2020
- Full Text
- View/download PDF
69. Connecting Low scale Seesaw for Neutrino Mass to Inelastic sub-GeV Dark Matter with Abelian Gauge Symmetry
- Author
-
Satyabrata Mahapatra, Narendra Sahu, and Debasish Borah
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,010308 nuclear & particles physics ,Dark matter ,FOS: Physical sciences ,Fermion ,QC770-798 ,01 natural sciences ,Lepton number ,MAJORANA ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Seesaw molecular geometry ,Nuclear and particle physics. Atomic energy. Radioactivity ,0103 physical sciences ,Neutrino ,010306 general physics ,Scalar field ,Gauge symmetry - Abstract
Motivated by the recently reported excess of electron recoil events by the XENON1T experiment, we propose low scale seesaw scenarios for light neutrino masses within $U(1)_X$ gauge extension of the standard model that also predicts stable as well as long lived dark sector particles. The new fields necessary for seesaw realisation as well as dark matter are charged under the $U(1)_X$ gauge symmetry in an anomaly free way. A singlet scalar field which effectively gives rise to lepton number violation and hence Majorana light neutrino masses either at tree or radiative level, also splits the dark matter field into two quasi-degenerate states. While sub-eV neutrino mass and non-zero dark matter mass splitting are related in this way, the phenomenology of sub-GeV scale inelastic dark matter can be very rich if the mass splitting is of keV scale. We show that for suitable parameter space, both the components with keV splitting can contribute to total dark matter density of the present universe, while opening up the possibility of the heavier dark matter candidate to undergo down-scattering with electrons. We check the parameter space of the model for both fermion and scalar inelastic dark matter candidates which can give rise to the XENON1T excess while being consistent with other phenomenological bounds. We also discuss the general scenario where mass splitting~$\Delta m$ between the two dark matter components can be larger, effectively giving rise to a single component dark matter scenario., Comment: 42 pages, 18 figures, Accepted for publication in Nucl. Phys. B more...
- Published
- 2020
70. TeV Scale Leptogenesis via Dark Sector
- Author
-
Arnab Dasgupta, Debasish Borah, and Sin Kyu Kang
- Subjects
Physics ,Particle physics ,media_common.quotation_subject ,High Energy Physics::Phenomenology ,Dark matter ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Asymmetry ,Universe ,Baryon ,Leptogenesis ,High Energy Physics::Experiment ,Neutrino ,Order of magnitude ,media_common ,Lepton - Abstract
We study the possibility of realising successful leptogenesis from dark matter annihilations in the scotogenic model of neutrino masses to explain the same order of magnitude abundance of dark matter and baryons in the present Universe, and show that the correct leptonic asymmetry, dark matter abundance and neutrino mass can be simultaneously achieved in the model. Interestingly, the scale of leptogenesis can be as low as 5 TeV, lower than the one in vanilla leptogenesis scenario in scotogenic model along with the additional advantage of explaining the baryon-dark matter coincidence. Due to such low scale, the model remains predictive at dark matter direct detection and rare decay experiments looking for charged lepton flavour violating processes more...
- Published
- 2020
- Full Text
- View/download PDF
71. Low Scale $U(1)_X$ Gauge Symmetry as an Origin of Dark Matter, Neutrino Mass and Flavour Anomalies
- Author
-
Soumitra Nandi, Lopamudra Mukherjee, and Debasish Borah
- Subjects
Nuclear and High Energy Physics ,Particle physics ,Dark matter ,FOS: Physical sciences ,01 natural sciences ,High Energy Physics - Experiment ,High Energy Physics - Experiment (hep-ex) ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,Heavy Quark Physics ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010306 general physics ,Gauge symmetry ,Physics ,Gauge boson ,Muon ,Anomalous magnetic dipole moment ,010308 nuclear & particles physics ,High Energy Physics::Phenomenology ,High Energy Physics - Phenomenology ,Beyond Standard Model ,lcsh:QC770-798 ,High Energy Physics::Experiment ,Neutrino ,Phenomenology (particle physics) ,Lepton - Abstract
We study a generic leptophilic $U(1)_X$ extension of the standard model with a light gauge boson. The $U(1)_X$ charge assignments for the leptons are guided by lepton universality violating (LUV) observables in semileptonic $b \to s\ell\ell$ decays, muon anomalous magnetic moment and the origin of leptonic masses and mixing. Anomaly cancellation conditions require the addition of new chiral fermions in the model, one of which acts as a dark matter (DM) candidate when it is stabilised by an additional $\mathcal{Z}_2$ symmetry. From our analysis, we show two different possible models with similar particle content that lead to quite contrasting neutrino mass origin and other phenomenology. The proposed models also have the potential to address the anomalous results in $b\to c\ell\nu_{\ell}$ decays like $R(D), R(D^*)$, electron anomalous magnetic moment and the very recent KOTO anomaly in the kaon sector. We also discuss different possible collider signatures of our models which can be tested in future., Comment: Version accepted for publication in JHEP, few references added, No major changes in manuscript more...
- Published
- 2020
72. Survey of Texture Zeros with Light Dirac Neutrinos
- Author
-
Debasish Borah and Happy Borgohain
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,010308 nuclear & particles physics ,Texture (cosmology) ,Dirac (video compression format) ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Mass matrix ,01 natural sciences ,Hermitian matrix ,Upper and lower bounds ,MAJORANA ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Computer Science::Graphics ,Computer Science::Computer Vision and Pattern Recognition ,0103 physical sciences ,Neutrino ,010306 general physics ,Lepton - Abstract
We classify all possible texture zeros in light neutrino mass matrix in diagonal charged lepton basis by considering Dirac nature of light neutrinos. For Hermitian nature of neutrino mass matrix, the number of possible texture zeros remain same as Majorana texture zeros, but with less free parameters due to the absence of additional Majorana CP phases. Relaxing the Hermitian nature of neutrino mass matrix lead to many more possibilities and freedom due to additional CP phases, mixing angles not constrained by neutrino data. While we find that none of the texture zeros in Hermitian case are allowed, in non-Hermitian case some textures even with four zeros are allowed. While most of the one-zero, two-zero and three-zero textures in this case are allowed, four-zero textures are tightly constrained with only 6 allowed out of 126 possibilities. The allowed textures also give interesting correlations between light neutrino parameters with sharp distinctions between normal and inverted mass ordering. Many of these allowed textures also saturate the Planck 2018 upper bound on the sum of absolute neutrino masses., 30 pages, 5 figures more...
- Published
- 2020
73. Observing Left-Right Symmetry in the Cosmic Microwave Background
- Author
-
Debasish Borah, Dibyendu Nanda, Chayan Majumdar, and Arnab Dasgupta
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,media_common.quotation_subject ,Cosmic microwave background ,Dark matter ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Fermion ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Universe ,symbols.namesake ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,symbols ,Higgs boson ,Planck ,Neutrino ,010306 general physics ,media_common ,Boson ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We consider the possibility of probing left-right symmetric model (LRSM) via cosmic microwave background (CMB). We adopt the minimal LRSM with Higgs doublets, also known as the doublet left-right model (DLRM), where all fermions including the neutrinos acquire masses only via their couplings to the Higgs bidoublet. Due to the Dirac nature of light neutrinos, there exist additional relativistic degrees of freedom which can thermalise in the early universe by virtue of their gauge interactions corresponding to the right sector. We constrain the model from Planck 2018 bound on the effective relativistic degrees of freedom and also estimate the prospects for planned CMB Stage IV experiments to constrain the model further. We find that $W_R$ boson mass below 4.06 TeV can be ruled out from Planck 2018 bound at $2\sigma$ CL in the exact left-right symmetric limit which is equally competitive as the LHC bounds from dijet resonance searches. On the other hand Planck 2018 bound at $1\sigma$ CL can rule out a much larger parameter space out of reach of present direct search experiments, even in the presence of additional relativistic degrees of freedom around the TeV corner. We also study the consequence of these constraints on dark matter in DLRM by considering a right handed real fermion quintuplet to be the dominant dark matter component in the universe., Comment: 29 pages, 8 figures, matches version accepted for publication in Phys. Rev. D more...
- Published
- 2020
- Full Text
- View/download PDF
74. Cosmic Inflation in Minimal $U(1)_{B-L}$ Model: Implications for (Non) Thermal Dark Matter and Leptogenesis
- Author
-
Suruj Jyoti Das, Debasish Borah, and Abhijit Kumar Saha
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Physics and Astronomy (miscellaneous) ,Dark matter ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Inflaton ,Symmetry (physics) ,Standard Model (mathematical formulation) ,General Relativity and Quantum Cosmology ,High Energy Physics - Phenomenology ,Baryon asymmetry ,High Energy Physics - Phenomenology (hep-ph) ,Leptogenesis ,Neutrino ,Engineering (miscellaneous) ,Gauge symmetry ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We study the possibility of realising cosmic inflation, dark matter (DM), baryon asymmetry of the universe (BAU) and light neutrino masses in non-supersymmetric minimal gauged $B-L$ extension of the standard model with three right handed neutrinos. The singlet scalar field responsible for spontaneous breaking of $B-L$ gauge symmetry also plays the role of inflaton by virtue of its non-minimal coupling to gravity. While the lightest right handed neutrino is the DM candidate, being stabilised by an additional $Z_2$ symmetry, we show by performing a detailed renormalisation group evolution (RGE) improved study of inflationary dynamics that thermal DM is generally overproduced due to insufficient annihilations through gauge and scalar portals. This happens due to strict upper limits obtained on gauge and other dimensionless couplings responsible for DM annihilation while assuming the non-minimal coupling to gravity to be at most of order unity. The non-thermal DM scenario is viable, with or without $Z_2$ symmetry, although in such a case the $B-L$ gauge sector remains decoupled from the inflationary dynamics due to tiny couplings. We also show that the reheat temperature predicted by the model prefers non-thermal leptogenesis with hierarchical right handed neutrinos while being consistent with other requirements., 48 pages, 18 figures, minor revision, matches version accepted for publication in Eur. Phys. J. C more...
- Published
- 2020
75. Alga‐mediated facile green synthesis of silver nanoparticles: Photophysical, catalytic and antibacterial activity
- Author
-
Pampi Sarmah, Ankita Bhattacharjee, Madhurya Chandel, Neeharika Das, Piyush Pandey, Chira R. Bhattacharjee, Nirmalendu Das, Jayashree Rout, Narendra Nath Ghosh, Debasish Borah, and Kheyali Ghosh
- Subjects
Inorganic Chemistry ,Chlorella ellipsoidea ,Chemistry ,Photocatalysis ,General Chemistry ,Antibacterial activity ,Combinatorial chemistry ,Silver nanoparticle ,Catalysis - Published
- 2020
- Full Text
- View/download PDF
76. Phenomenological study of texture zeros of neutrino mass matrix in minimal left-right symmetric model
- Author
-
Mrinal Kumar Das, Debasish Borah, and Happy Borgohain
- Subjects
Physics ,History ,Particle physics ,Texture (cosmology) ,Computer Science::Information Retrieval ,Dirac (video compression format) ,Physics beyond the Standard Model ,High Energy Physics::Phenomenology ,Zero (complex analysis) ,FOS: Physical sciences ,Mass matrix ,Computer Science Applications ,Education ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Double beta decay ,High Energy Physics::Experiment ,Neutrino ,Free parameter - Abstract
We studied the phenomenological implications of texture zeros in the neutrino mass matrix of the minimal left-right symmetric model (LRSM). Since the possibility of maximum zeros reduces the maximum number of free parameters of the model making it more predictive, we considered only those cases with maximum possible texture zeros in light neutrino mass matrix $M_{\nu}$, Dirac neutrino mass matrix $M_D$ and heavy right-handed (RH) neutrino mass matrix $M_{RR}$. We then computed the correlations among the different light neutrino parameters and then the new physics contributions to neutrinoless double beta decay (NDBD) for the different texture zero cases. We find that for RH neutrino masses above 1 GeV, the new physics contributions to NDBD can saturate the corresponding experimental bound., Comment: TAUP19 proceedings more...
- Published
- 2020
77. Observable Gravitational Waves in Minimal Scotogenic Model
- Author
-
Kohei Fujikura, Devabrat Mahanta, Sin Kyu Kang, Arnab Dasgupta, and Debasish Borah
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,Gravitational wave ,Scalar (mathematics) ,Electroweak interaction ,Dark matter ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Astronomy and Astrophysics ,01 natural sciences ,Standard Model ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,Neutrino ,Resummation ,Lepton ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We scrutinise the widely studied minimal scotogenic model of dark matter (DM) and radiative neutrino mass from the requirement of a strong first order electroweak phase transition (EWPT) and observable gravitational waves at future planned space based experiments. The scalar DM scenario is similar to inert scalar doublet extension of standard model where a strong first order EWPT favours a portion of the low mass regime of DM which is disfavoured by the latest direct detection bounds. In the fermion DM scenario, we get newer region of parameter space which favours strong first order EWPT as the restriction on mass ordering within inert scalar doublet gets relaxed. While such leptophilic fermion DM remains safe from stringent direct detection bounds, newly allowed low mass regime of charged scalar can leave tantalising signatures at colliders and can also induce charged lepton flavour violation within reach of future experiments. While we get such new region of parameter space satisfying DM relic, strong first order EWPT with detectable gravitational waves, light neutrino mass and other relevant constraints, we also improve upon previous analysis in similar model by incorporating appropriate resummation effects in effective finite temperature potential., 36 pages, 6 figures, matches version accepted for publication in JCAP more...
- Published
- 2020
78. Boosted Self-Interacting Dark Matter and XENON1T Excess
- Author
-
Debasish, Borah, Manoranjan, Dutta, Satyabrata, Mahapatra, Narendra, Sahu, Debasish, Borah, Manoranjan, Dutta, Satyabrata, Mahapatra, and Narendra, Sahu
- Abstract
We propose a self-interacting boosted dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. The Standard Model has been extended with two vector-like fermion singlets charged under a dark U(1)D gauge symmetry to describe the dark sector. While the presence of light vector boson mediator leads to sufficient DM self-interactions to address the small scale issues of cold dark matter, the model with GeV scale DM can explain the XENON1T excess via scattering of boosted DM component with electrons at the detector. The requirement of large annihilation rate of heavier DM into the lighter one for sufficient boosted DM flux leads to suppressed thermal relic abundance. A hybrid setup of thermal and non-thermal contribution from late decay of a scalar can lead to correct relic abundance. All these requirements leave a very tiny parameter space for sub-GeV DM keeping the model very predictive for near future experiments. more...
- Published
- 2021
79. Composition controllable green synthesis of manganese dioxide nanoparticles using an edible freshwater red alga and its photocatalytic activity towards water soluble toxic dyes
- Author
-
Debasish Borah, Jayashree Rout, Debika Gogoi, Narendra Nath Ghosh, and Chira R. Bhattacharjee
- Subjects
Inorganic Chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry - Published
- 2022
- Full Text
- View/download PDF
80. Low scale leptogenesis and dark matter in the presence of primordial black holes
- Author
-
Debasish Borah, Devabrat Mahanta, and Suruj Jyoti Das
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,media_common.quotation_subject ,Dark matter ,FOS: Physical sciences ,Astronomy and Astrophysics ,Primordial black hole ,Asymmetry ,Cosmology ,Baryon ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Leptogenesis ,Neutrino ,Astrophysics - Cosmology and Nongalactic Astrophysics ,media_common ,Lepton - Abstract
We study the possibility of low scale leptogenesis along with dark matter (DM) in the presence of primordial black holes (PBH). For a common setup to study both leptogenesis and DM we consider the minimal scotogenic model which also explains light neutrino mass at radiative level. While PBH in the mass range of $0.1-10^5$ g can, in principle, affect leptogenesis, the required initial PBH fraction usually leads to overproduction of scalar doublet DM whose thermal freeze-out occurs before PBH evaporation. PBH can lead to non-thermal source of leptogenesis as well as dilution of thermally generated lepton asymmetry via entropy injection, with the latter being dominant. The parameter space of scotogenic model which leads to overproduction of baryon or lepton asymmetry in standard cosmology can be made consistent in the presence of PBH with appropriate initial mass and energy fraction. On the other hand, for such PBH parameters, the scalar DM is constrained to be in light mass regime where its freeze-out occurs after PBH evaporation. We then discuss the possibility of fermion singlet DM with $N_2$ leptogenesis in the same model where due to singlet nature of DM, its connection with PBH parameters and hence leptogenesis becomes stronger compared to the previous case., Comment: 44 pages, 17 captioned figures, to appear in JCAP more...
- Published
- 2021
- Full Text
- View/download PDF
81. Light Dirac neutrino portal dark matter with observable ΔN eff
- Author
-
Dibyendu Nanda, Debasish Borah, and Anirban Biswas
- Subjects
Physics ,Particle physics ,Dark matter ,Dirac (software) ,Astronomy and Astrophysics ,Observable ,Neutrino - Abstract
We propose a Dirac neutrino portal dark matter scenario by minimally extending the particle content of the Standard Model (SM) with three right-handed neutrinos (ν R ), a Dirac fermion dark matter candidate (ψ) and a complex scalar (ϕ), all of which are singlets under the SM gauge group. An additional ℤ4 symmetry has been introduced for the stability of dark matter candidate ψ and also ensuring the Dirac nature of light neutrinos at the same time. Both the right handed neutrinos and the dark matter thermalise with the SM plasma due to a new Yukawa interaction involving ν R , ψ and ϕ while the latter maintains thermal contact via the Higgs portal interaction. The decoupling of ν R occurs when ϕ loses its kinetic equilibrium with the SM plasma and thereafter all three ℤ4 charged particles form an equilibrium among themselves with a temperature TνR . The dark matter candidate ψ finally freezes out within the dark sector and preserves its relic abundance. We have found that in the present scenario, some portion of low mass dark matter (M ψ ≲ 10 GeV) is already excluded by the Planck 2018 data for keeping ν R s in the thermal bath below a temperature of 600 MeV and thereby producing an excess contribution to N eff. The next generation experiments like CMB-S4, SPT-3G etc. will have the required sensitivities to probe the entire model parameter space of this minimal scenario, especially the low mass range of ψ where direct detection experiments are still not capable enough for detection. more...
- Published
- 2021
- Full Text
- View/download PDF
82. Type III Seesaw and Two-Component Dark Matter in $$U(1)_{B-L}$$ Model
- Author
-
Anirban Biswas, Dibyendu Nanda, and Debasish Borah
- Subjects
Physics ,Gauge boson ,Particle physics ,High Energy Physics::Lattice ,High Energy Physics::Phenomenology ,Type (model theory) ,Lepton number ,Standard Model ,symbols.namesake ,Seesaw mechanism ,Seesaw molecular geometry ,Dirac fermion ,symbols ,Production (computer science) - Abstract
We have studied gauged \(\mathrm{U(1)_{B-L}}\) extension of the Standard Model where neutrino masses are generated from type III seesaw mechanism. Instead of three right handed neutrinos having unit lepton number each, which is so called the minimal \(B-L\) model, the model with three fermion triplets will introduce new anomaly in the theory. Two neutral Dirac fermions having fractional \(B-L\) charges, both of which are naturally stable by virtue of a remnant \(\mathbb {Z}_2 \times \mathbb {Z}'_2\) symmetry, will also be necessary to cancel the leftover triangle anomalies. We have shown that the model can be constrained from various relevant phenomenological bounds. Another interesting property of this model is that due to the presence of additional neutral gauge bosons there can be an enhanced production of the fermion triplet in collider experiments. more...
- Published
- 2020
- Full Text
- View/download PDF
83. Right-handed neutrino dark matter with radiative neutrino mass in gauged B − L model
- Author
-
Dibyendu Nanda, Debasish Borah, Nimmala Narendra, and Narendra Sahu
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,010308 nuclear & particles physics ,B − L ,Flavour ,Dark matter ,High Energy Physics::Phenomenology ,Parameter space ,01 natural sciences ,Vertex (geometry) ,0103 physical sciences ,Radiative transfer ,lcsh:QC770-798 ,High Energy Physics::Experiment ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,Neutrino ,010306 general physics ,Lepton - Abstract
We study the possibility of right-handed neutrino dark matter (DM) in gauged U(1)B−L×Z2 extension of the standard model augmented by an additional scalar doublet, being odd under the Z2 symmetry, to give rise the scotogenic scenario of radiative neutrino masses. Due to lepton portal interactions, the right-handed neutrino DM can have additional co-annihilation channels apart from the usual annihilations through ZB−L which give rise to much more allowed mass of DM from relic abundance criteria, even away from the resonance region like MDM≈MZB−L/2. This enlarged parameter space is found to be consistent with neutrino mass constraints while being sensitive to direct detection experiments of DM as well as rare decay experiments looking for charged lepton flavour violating decays like μ→eγ. Due to the possibility of the Z2 odd scalar doublet being the next to lightest stable particle that can be sufficiently produced in colliders by virtue of its gauge interactions, one can have interesting signatures like displaced vertex or disappearing charged tracks provided that the mass splitting δM between DM and the next to lightest stable particle (NLSP) is small. In particular, if δM
more... - Published
- 2020
84. Correlating the anomalous results in b→s decays with inert Higgs doublet dark matter and the muon g−2
- Author
-
Lopamudra Mukherjee, Basabendu Barman, Debasish Borah, and Soumitra Nandi
- Subjects
Physics ,Particle physics ,Muon ,Large Hadron Collider ,Missing energy ,High Energy Physics::Phenomenology ,Dark matter ,Higgs boson ,High Energy Physics::Experiment ,Singlet state ,Fermion ,Luminosity - Abstract
In this article, we have considered an extension of the inert Higgs doublet model with $SU(2{)}_{L}$ singlet vectorlike fermions. Our model is capable of addressing some interesting anomalous results in $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ decays [like $R({K}^{(*)})$] and in muon ($g\ensuremath{-}2$). Apart from explaining these anomalies, and being consistent with other flavor data, the model satisfies relevant constraints in the dark matter sector, while remaining within the reach of ongoing direct detection experiments. The model also produces signatures at the large hadron collider (LHC) with final states comprised of dilepton, dijet and missing energy, providing signals to be probed at higher luminosity. more...
- Published
- 2019
- Full Text
- View/download PDF
85. Flavoured gauge extension of singlet-doublet fermionic dark matter: neutrino mass, high scale validity and collider signatures
- Author
-
Debasish Borah, Basabendu Barman, Purusottam Ghosh, and Abhijit Kumar Saha
- Subjects
Physics ,Nuclear and High Energy Physics ,Gauge boson ,Particle physics ,Large Hadron Collider ,Dark matter ,Electroweak interaction ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Cosmology of Theories beyond the SM ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Seesaw mechanism ,Gauge Symmetry ,Beyond Standard Model ,lcsh:QC770-798 ,Neutrino Physics ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,High Energy Physics::Experiment ,Neutrino ,Gauge symmetry ,Lepton - Abstract
We propose an Abelian gauged version of the singlet-doublet fermionic dark matter (DM) model where DM, combination of a vector like fermion doublet and a fermion singlet, is naturally stabilised by the gauge symmetry without requiring any ad-hoc discrete symmetries. In order to have good detection prospects at collider experiments like the large hadron collider (LHC) and enlarged parameter space for low mass DM, we consider the additional gauge symmetry to be based on the quantum $B-3L_{\tau}$ where the restriction to third generation of leptons is chosen to have weaker bounds from the LHC on the corresponding gauge boson. The triangle anomalies arising in this model can be cancelled by including a right handed neutrino which takes part in generating light neutrino masses through type I seesaw mechanism. Apart from DM, collider prospects and light neutrino masses, the model also offers high scale validity giving rise to a stable electroweak vacuum and perturbative couplings all the way up to the Planck scale. We constrain our model parameters from these requirements as well as existing relevant constraints related to DM and colliders., Comment: 56 pages, 20 figures, matches version accepted for publication in JHEP more...
- Published
- 2019
86. Planck scale origin of nonzero <math><msub><mi>θ</mi><mn>13</mn></msub></math> and super-WIMP dark matter
- Author
-
Biswajit Karmakar, Debasish Borah, and Dibyendu Nanda
- Subjects
Physics ,Particle physics ,010308 nuclear & particles physics ,Dark matter ,High Energy Physics::Phenomenology ,Massive particle ,Fermion ,01 natural sciences ,Gravitation ,symbols.namesake ,High Energy Physics - Phenomenology ,WIMP ,0103 physical sciences ,symbols ,High Energy Physics::Experiment ,Neutrino ,Planck ,010306 general physics ,Phenomenology (particle physics) ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We study a discrete flavour symmetric scenario for neutrino mass and dark matter under the circumstances where such global discrete symmetries can be explicitly broken at Planck scale, possibly by gravitational effects. Such explicit breaking of discrete symmetries mimic as Planck suppressed operators in the model which can have non-trivial consequences for neutrino and dark matter sectors. In particular, we study a flavour symmetric model which, at renormalisable level, gives rise to tri-bimaximal type neutrino mixing with vanishing reactor mixing angle $\theta_{13}=0$, a stable inert scalar doublet behaving like a weakly interacting massive particle (WIMP) and a stable singlet inert fermion which does not interact with any other particles. The introduction of Planck suppressed operators which explicitly break the discrete symmetries, can give rise to the generation of non-zero $\theta_{13}$ in agreement with neutrino data and also open up decay channels of inert scalar doublet into singlet neutral inert fermion leading to the realisation of the super-WIMP dark matter scenario. We show that the correct neutrino phenomenology can be obtained in this model while discussing three distinct realisation of the super-WIMP dark matter scenario., Comment: 38 pages, 13 figures, to appear in Physical Review D more...
- Published
- 2019
87. Leptogenesis from Dark Matter Annihilations in Scotogenic Model
- Author
-
Sin Kyu Kang, Arnab Dasgupta, and Debasish Borah
- Subjects
Physics ,Particle physics ,Physics beyond the Standard Model ,media_common.quotation_subject ,High Energy Physics::Phenomenology ,Dark matter ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Universe ,Minimal model ,Baryon ,Leptogenesis ,High Energy Physics::Experiment ,Neutrino ,Lepton ,media_common - Abstract
We address the possibility of realizing successful leptogenesis from dark matter annihilations in the scotogenic model of neutrino masses to explain the same order of magnitude abundance of dark matter and baryons in the present Universe. After showing that the minimal model in this category cannot satisfy all these requirements, we study a minimal extension of this model and find that the scale of leptogenesis can be as low as 5 TeV, lower than the one in vanilla leptogenesis scenario in scotogenic model along with the additional advantage of explaining the baryon-dark matter coincidence. Due to such low scale, the model remains predictive at dark matter direct detection and rare decay experiments looking for charged lepton flavour violating processes. more...
- Published
- 2019
- Full Text
- View/download PDF
88. Connecting ANITA Anomalous Events to a Non-thermal Dark Matter Scenario
- Author
-
Gaurav Tomar, Debasish Borah, Arnab Dasgupta, and Ujjal Kumar Dey
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Thermal equilibrium ,Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,media_common.quotation_subject ,Dark matter ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Coupling (probability) ,01 natural sciences ,Universe ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,High Energy Physics::Experiment ,Neutrino ,010306 general physics ,Nucleon ,Astrophysics - High Energy Astrophysical Phenomena ,Event (particle physics) ,Lepton ,media_common ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
The ANtarctic Impulsive Transient Antenna (ANITA) collaboration has observed two EeV-energy, upward going events originating from below the horizon. As no standard model (SM) particles, propagating through the earth at such energy and exit angles, can give rise to the required survival probability for the observed events, several beyond standard model (BSM) proposals have come up. We propose a scenario where a $Z_2$ odd sector is responsible for such anomalous events. The next to lightest $Z_2$ odd particle or the next to lightest stable particle (NLSP), created from ultra high energy neutrino interactions with nucleons, can pass through the earth and then decay into the lightest $Z_2$ odd particle or the lightest stable particle (LSP) and a tau lepton. The long-lived nature of the NLSP requires its coupling with the LSP to be very small, keeping the LSP out of thermal equilibrium in the early universe. The LSP can then be a non-thermal dark matter while the tau leptons produced from NLSP decay after passing through the earth can explain the ANITA events. We first show that a purely non-thermal dark matter scenario can not give rise to the required event rates while a hybrid scenario where dark matter can have both thermal as a well non-thermal contribution to its relic abundance, serves the purpose., 21 pages, 6 figures, accepted for publication in Physical Review D more...
- Published
- 2019
89. Minimal Two-component Scalar Doublet Dark Matter with Radiative Neutrino Mass
- Author
-
Arunansu Sil, Rishav Roshan, and Debasish Borah
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Dark matter ,Scalar (mathematics) ,High Energy Physics::Phenomenology ,Yukawa potential ,FOS: Physical sciences ,Symmetry (physics) ,Standard Model ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Radiative transfer ,Component (group theory) ,Neutrino ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We propose a minimal extension of the Standard Model to accommodate two-component dark matter (DM) and light neutrino mass. The symmetry of the Standard Model is enhanced by an unbroken $\mathbb{Z}_2 \times \mathbb{Z}'_2$ such that being odd under each $\mathbb{Z}_2$, there exists one right handed neutrino and one inert scalar doublet. Therefore, each of the $\mathbb{Z}_2$ sectors contribute to ($i$) light neutrino masses radiatively similar to the scotogenic models while ($ii$) the two neutral CP even scalars present in two additional inert doublets play the role of dark matters. Focusing on the intermediate range of inert scalar doublet DM scenario: $M_W \leq M_{\rm DM} \lesssim 500 \; {\rm GeV}$, where one scalar doublet DM can not satisfy correct relic, we show that this entire range becomes allowed within this two-component scalar doublet DM, thanks to the inter-conversion between the two DM candidates in presence of neutrino Yukawa couplings with dark sector., 33 pages, 13 figures, matches version accepted by Physical Review D more...
- Published
- 2019
90. Phenomenological Study of Texture Zeros in Lepton Mass Matrices of Minimal Left-Right Symmetric Model
- Author
-
Mrinal Kumar Das, Debasish Borah, and Happy Borgohain
- Subjects
Nuclear and High Energy Physics ,Particle physics ,Physics beyond the Standard Model ,Spontaneous symmetry breaking ,FOS: Physical sciences ,01 natural sciences ,High Energy Physics - Phenomenology (hep-ph) ,Seesaw molecular geometry ,Double beta decay ,0103 physical sciences ,Neutrino Physics ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010306 general physics ,Physics ,Gauge boson ,010308 nuclear & particles physics ,Computer Science::Information Retrieval ,High Energy Physics::Phenomenology ,Mass matrix ,Spontaneous Symmetry Breaking ,High Energy Physics - Phenomenology ,Beyond Standard Model ,lcsh:QC770-798 ,High Energy Physics::Experiment ,Neutrino ,Lepton - Abstract
We consider the possibility of texture zeros in lepton mass matrices of the minimal left-right symmetric model (LRSM) where light neutrino mass arises from a combination of type I and type II seesaw mechanisms. Based on the allowed texture zeros in light neutrino mass matrix from neutrino and cosmology data, we make a list of all possible allowed and disallowed texture zeros in Dirac and heavy neutrino mass matrices which appear in type I and type II seesaw terms of LRSM. For the numerical analysis we consider those cases with maximum possible texture zeros in light neutrino mass matrix $M_{\nu}$, Dirac neutrino mass matrix $M_D$, heavy neutrino mass matrix $M_{RR}$ while keeping the determinant of $M_{RR}$ non-vanishing, in order to use the standard type I seesaw formula. The possibility of maximum zeros reduces the free parameters of the model making it more predictive. We then compute the new physics contributions to rare decay processes like neutrinoless double beta decay, charged lepton flavour violation. We find that even for a conservative lower limit on a left-right symmetry scale corresponding to heavy charged gauge boson mass 4.5 TeV, in agreement with collider bounds, for right-handed neutrino masses above 1 GeV, the new physics contributions to these rare decay processes can saturate the corresponding experimental bound., Comment: 49 pages, 30 figures, 6 tables, typos corrected, more references and discussion added, to appear in JHEP more...
- Published
- 2019
91. Two-component Dark Matter with co-genesis of Baryon Asymmetry of the Universe
- Author
-
Sin Kyu Kang, Arnab Dasgupta, and Debasish Borah
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,media_common.quotation_subject ,Dark matter ,Massive particle ,FOS: Physical sciences ,01 natural sciences ,Universe ,High Energy Physics - Phenomenology ,Baryon asymmetry ,High Energy Physics - Phenomenology (hep-ph) ,WIMP ,Leptogenesis ,0103 physical sciences ,Warm dark matter ,Neutrino ,010306 general physics ,media_common ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We discuss the possibility of realising a two-component dark matter (DM) scenario where the two DM candidates differ from each other by virtue of their production mechanism in the early universe. One of the DM candidates is thermally generated in a way similar to the weakly interacting massive particle (WIMP) paradigm where the DM abundance is governed by its freeze-out while the other candidate is produced only from non-thermal contributions similar to freeze-in mechanism. We discuss this in a minimal extension of the standard model where light neutrino masses arise radiatively in a way similar to the scotogenic models with DM particles going inside the loop. The lepton asymmetry is generated at the same time from WIMP DM annihilations as well as partially from the mother particle for non-thermal DM. This can be achieved while satisfying the relevant experimental bounds, and keeping the scale of leptogenesis or the thermal DM mass as low as 3 TeV, well within present experimental reach. In contrast to the TeV scale thermal DM mass, the non-thermal DM can be as low as a few keV, giving rise to the possibility of a sub-dominant warm dark matter (WDM) component that can have interesting consequences on structure formation. The model also has tantalizing prospects of being detected at ongoing direct detection experiments as well as the ones looking for charged lepton flavour violating process like $\mu \rightarrow e \gamma$., Comment: 29 pages, 9 figures, matches version accepted for publication in Phys. Rev. D more...
- Published
- 2019
92. Effective theory of freeze-in dark matter
- Author
-
Basabendu Barman, Debasish Borah, and Rishav Roshan
- Subjects
Physics ,Particle physics ,010308 nuclear & particles physics ,High Energy Physics::Phenomenology ,Electroweak interaction ,Dark matter ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Lepton number ,Standard Model ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,Effective field theory ,Symmetry breaking ,Neutrino ,Majorana fermion - Abstract
We perform a model independent study of freeze-in of massive particle dark matter (DM) by adopting an effective field theory framework. Considering the dark matter to be a gauge singlet Majorana fermion, odd under a stabilising symmetry $Z_2$ under which all standard model (SM) fields are even, we write down all possible DM-SM operators upto and including mass dimension eight. For simplicity of the numerical analysis we restrict ourselves only to the scalar operators in SM as well as in the dark sector. We calculate the DM abundance for each such dimension of operator considering both UV and IR freeze-in contributions which can arise before and after the electroweak symmetry breaking respectively. After constraining the cut-off scale and reheat temperature of the universe from the requirement of correct DM relic abundance, we also study the possibility of connecting the origin of neutrino mass to the same cut-off scale by virtue of lepton number violating Weinberg operators. We thus compare the bounds on such cut-off scale and corresponding reheat temperature required for UV freeze-in from the origin of light neutrino mass as well as from the requirement of correct DM relic abundance. We also briefly comment upon the possibilities of realising such DM-SM effective operators in a UV complete model., Comment: 60 pages, 6 tables, 11 figures, added two new sections, accepted for publication in JCAP more...
- Published
- 2020
- Full Text
- View/download PDF
93. Revisiting Majorana neutrino textures in the light of dark LMA
- Author
-
Debasish Borah and Happy Borgohain
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,010308 nuclear & particles physics ,Texture (cosmology) ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Solar neutrino problem ,Mass matrix ,01 natural sciences ,Cosmology ,High Energy Physics - Phenomenology ,MAJORANA ,High Energy Physics - Phenomenology (hep-ph) ,Double beta decay ,0103 physical sciences ,Neutrino ,010306 general physics ,Neutrino oscillation - Abstract
We study the possibility of texture zeros in Majorana light neutrino mass matrix in the light of dark large mixing angle (DLMA) solution to solar neutrino problem where solar mixing angle ($\sin^2{\theta_{12}}\simeq 0.7 $) lies in the second octant instead of first octant in standard large mixing angle (LMA) scenario ($\sin^2{\theta_{12}}\simeq 0.3 $). In three neutrino scenario, we find that LMA and DLMA solutions lead to different set of allowed and disallowed textures with one and two zeros. While being consistent with existing bounds from neutrino oscillation data, neutrinoless double beta decay and cosmology these allowed textures also lead to interesting correlations among light neutrino parameters which can distinguish LMA from DLMA solution. We also check the implications for texture zeros in $3+1$ neutrino scenario using both LMA and DLMA solutions. While LMA and DLMA solutions do not play decisive role in ruling out texture zeros in this case, they do give rise to distinct predictions and correlations between light neutrino parameters., Comment: 37 pages, 10 figures, Journal accepted version more...
- Published
- 2020
- Full Text
- View/download PDF
94. In-Situ Nutrient Recycling and Management
- Author
-
Sarat Sekhar Bora and Debasish Borah
- Published
- 2020
- Full Text
- View/download PDF
95. Connecting Light Dirac Neutrinos to a Multi-component Dark Matter Scenario in Gauged $B-L$ Model
- Author
-
Debasish Borah and Dibyendu Nanda
- Subjects
Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Physics and Astronomy (miscellaneous) ,Spontaneous symmetry breaking ,High Energy Physics::Lattice ,Dirac (software) ,Dark matter ,FOS: Physical sciences ,lcsh:Astrophysics ,Computer Science::Digital Libraries ,Standard Model ,symbols.namesake ,High Energy Physics - Phenomenology (hep-ph) ,lcsh:QB460-466 ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,Symmetry breaking ,Engineering (miscellaneous) ,Physics ,High Energy Physics::Phenomenology ,High Energy Physics - Phenomenology ,Dirac fermion ,symbols ,Higgs boson ,lcsh:QC770-798 ,Neutrino ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We propose a new gauged $B-L$ extension of the standard model where light neutrinos are of Dirac type, naturally acquiring sub-eV mass after electroweak symmetry breaking, without any additional global symmetries. This is realised by choosing a different $B-L$ charge for right handed neutrinos than the usual $-1$ so that the Dirac Yukawa coupling involves an additional neutrinophilic scalar doublet instead of the usual Higgs doublet. The model can be made anomaly free by considering four additional chiral fermions which give rise to two massive Dirac fermions by appropriate choice of singlet scalars. The choice of scalars not only helps in achieving the desired particle mass spectra via spontaneous symmetry breaking, but also leaves a remnant $Z_2 \times Z'_2$ symmetry to stabilise the two dark matter candidates. Apart from this interesting link between Dirac nature of light neutrinos and multi-component dark matter sector, we also find that the dark matter parameter space is constrained mostly by the cosmological upper limit on effective relativistic degrees of freedom $\Delta N_{\rm eff}$ which gets enhanced in this model due to the thermalisation of the light right handed neutrinos by virtue of their sizeable $B-L$ gauge interactions., Comment: 34 pages, 6 figures. matches version accepted for publication in Eur. Phys. J. C more...
- Published
- 2019
- Full Text
- View/download PDF
96. Common origin of modified chaotic inflation, non thermal dark matter and Dirac neutrino mass
- Author
-
Debasish Borah, Dibyendu Nanda, and Abhijit Kumar Saha
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,media_common.quotation_subject ,Dark matter ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Universe ,Cosmology ,Standard Model ,Higgs field ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,Neutrino ,010306 general physics ,Eternal inflation ,Scalar field ,media_common ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We propose a minimal extension of the standard model of particle physics to accommodate cosmic inflation, dark matter and light neutrino masses. While the inflationary phase is obtained from a modified chaotic inflation scenario, consistent with latest cosmology data, the dark matter particle is a fermion singlet which remains out of equilibrium in the early universe. The scalar field which revives the chaotic inflation scenario by suitable modification also assists in generating tiny couplings of dark matter with its mother particle, naturally realizing the non-thermal or freeze-in type dark matter scenario. Interestingly, the same assisting scalar field also helps in realizing tiny Yukawa couplings required to generate sub-eV Dirac neutrino mass from neutrino couplings to the standard model like Higgs field. The minimality as well as providing a unified solution to all three problems keep the model predictive at experiments spanning out to all frontiers., Comment: 25 pages, 5 figures, matches version accepted for publication in Phys. Rev. D more...
- Published
- 2019
- Full Text
- View/download PDF
97. Type III Seesaw for Neutrino Masses in $U(1)_{B-L}$ Model with Multi-component Dark Matter
- Author
-
Dibyendu Nanda, Anirban Biswas, and Debasish Borah
- Subjects
Nuclear and High Energy Physics ,Particle physics ,Dark matter ,FOS: Physical sciences ,Computer Science::Digital Libraries ,01 natural sciences ,Standard Model ,High Energy Physics - Phenomenology (hep-ph) ,Seesaw molecular geometry ,0103 physical sciences ,Neutrino Physics ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,010306 general physics ,Physics ,Gauge boson ,010308 nuclear & particles physics ,High Energy Physics::Phenomenology ,Fermion ,Cosmology of Theories beyond the SM ,Lepton number ,High Energy Physics - Phenomenology ,Seesaw mechanism ,Beyond Standard Model ,Computer Science::Mathematical Software ,lcsh:QC770-798 ,Neutrino - Abstract
We propose a $B-L$ gauged extension of the Standard Model where light neutrino masses arise from type III seesaw mechanism. Unlike the minimal $B-L$ model with three right handed neutrinos having unit lepton number each, the model with three fermion triplets is however not anomaly free. We show that the leftover triangle anomalies can be cancelled by two neutral Dirac fermions having fractional $B-L$ charges, both of which are naturally stable by virtue of a remnant $\mathbb{Z}_2 \times \mathbb{Z}'_2$ symmetry, naturally leading to a two component dark matter scenario without any ad-hoc symmetries. We constrain the model from all relevant phenomenological constraints including dark matter properties. Light neutrino mass and collider prospects are also discussed briefly. Due to additional neutral gauge bosons, the fermion triplets in type III seesaw can have enhanced production cross section in collider experiment., Comment: 50 pages,11 figures, 5 tables, version accepted for publication in JHEP more...
- Published
- 2019
- Full Text
- View/download PDF
98. TeV scale leptogenesis with dark matter in non-standard cosmology
- Author
-
Devabrat Mahanta and Debasish Borah
- Subjects
Physics ,Particle physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,010308 nuclear & particles physics ,media_common.quotation_subject ,Dark matter ,FOS: Physical sciences ,Astronomy and Astrophysics ,Non-standard cosmology ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Universe ,Metric expansion of space ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,Baryon asymmetry ,Nucleosynthesis ,Leptogenesis ,0103 physical sciences ,Neutrino ,Astrophysics - Cosmology and Nongalactic Astrophysics ,media_common - Abstract
We study the consequence of a non-standard cosmological epoch in the early universe on the generation of baryon asymmetry through leptogenesis as well as dark matter abundance. We consider two different non-standard epochs: one where a scalar field behaving like pressure-less matter dominates the early universe, known as early matter domination (EMD) scenario while in the second scenario, the energy density of the universe is dominated by a component whose energy density red-shifts faster than radiation, known as fast expanding universe (FEU) scenario. While a radiation dominated universe is reproduced by the big bang nucleosynthesis (BBN) epoch in both the scenario, the high scale phenomena like generation of baryon asymmetry and dark matter relic get significantly affected. Adopting a minimal particle physics framework known as the scotogenic model which generates light neutrino masses at one-loop level, we find that in one specific realisation of EMD scenario, the scale of leptogenesis can be lower than that in a standard cosmological scenario. The other non-standard cosmological scenarios, on the other hand, can be constrained from the requirement of successful low scale leptogenesis and generating correct dark matter abundance simultaneously. Such a low scale scenario not only gives a unified picture of baryon asymmetry, dark matter and origin of neutrino mass but also opens up interesting possibilities for experimental detection., Comment: 45 pages, 22 figures, matches version accepted for publication in JCAP more...
- Published
- 2020
- Full Text
- View/download PDF
99. Common origin of nonzero θ13 and baryon asymmetry of the Universe in a TeV scale seesaw model with A4 flavor symmetry
- Author
-
Debasish Borah, Ananya Mukherjee, and Mrinal Kumar Das
- Subjects
Physics ,Particle physics ,010308 nuclear & particles physics ,Physics beyond the Standard Model ,High Energy Physics::Phenomenology ,Mass matrix ,01 natural sciences ,Seesaw mechanism ,Baryon asymmetry ,Seesaw molecular geometry ,Leptogenesis ,0103 physical sciences ,CP violation ,High Energy Physics::Experiment ,Neutrino ,010306 general physics - Abstract
We study the possibility of generating nonzero reactor mixing angle ${\ensuremath{\theta}}_{13}$ and baryon asymmetry of the Universe within the framework of an ${A}_{4}$ flavor symmetric model. Using the conventional type I seesaw mechanism we construct the Dirac and Majorana mass matrices that give rise to the correct light neutrino mass matrix. Keeping the right-handed neutrino mass matrix structure trivial so that it gives rise to a (quasi) degenerate spectrum of heavy neutrinos suitable for resonant leptogenesis at TeV scale, we generate the nontrivial structure of Dirac neutrino mass matrix that can lead to the light neutrino mixing through the type I seesaw formula. Interestingly, such a setup naturally leads to nonzero ${\ensuremath{\theta}}_{13}$ due to the existence of antisymmetric contraction of the product of two triplet representations of ${A}_{4}$. Such an antisymmetric part of the triplet products usually vanishes for right-handed neutrino Majorana mass terms, leading to $\ensuremath{\mu}\ensuremath{-}\ensuremath{\tau}$ symmetric scenarios in the most economical setups. We constrain the model parameters from the requirement of producing the correct neutrino data as well as baryon asymmetry of the Universe for right-handed neutrino mass scale around TeV. The ${A}_{4}$ symmetry is augmented by additional ${Z}_{3}\ifmmode\times\else\texttimes\fi{}{Z}_{2}$ symmetry to make sure that the splitting between right-handed neutrinos required for resonant leptogenesis is generated only by next to leading order terms, making it naturally small. We find that the inverted hierarchical light neutrino masses give more allowed parameter space consistent with neutrino and baryon asymmetry data. more...
- Published
- 2018
- Full Text
- View/download PDF
100. Flowering to bloom of PeV scale supersymmetric left–right symmetric models
- Author
-
Anishnu Sarkar, Debasish Borah, Sasmita Mishra, and Urjit A. Yajnik
- Subjects
Physics ,Particle physics ,Left-Right Symmetry ,010308 nuclear & particles physics ,Physics beyond the Standard Model ,Spontaneous symmetry breaking ,General Physics and Astronomy ,Supersymmetry ,Breaking ,Mass ,Domain Walls ,01 natural sciences ,Upper and lower bounds ,Supersymmetry breaking ,Parity ,Explicit symmetry breaking ,Metastable Vacua ,0103 physical sciences ,Grand Unified Theory ,Symmetry breaking ,Neutrino Mass ,010306 general physics - Abstract
Unified models incorporating right-handed neutrino in a symmetric way generically possess parity symmetry. If this is broken spontaneously, it results in the formation of domain walls in the early Universe, whose persistence is unwanted. A generic mechanism for the destabilization of such walls is a small pressure difference signalled by difference in free energy across the walls. It is interesting to explore the possibility of such effects in conjunction with the effects that break supersymmetry in a phenomenologically acceptable way. This possibility when realized in the context of several scenarios of supersymmetry breaking, leads to an upper bound on the scale of spontaneous parity breaking, often much lower than the GUT scale. In the left-right symmetric models studied, the upper bound is no higher than 10(11) GeV but a scale as low as 10(5) GeV is acceptable. more...
- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.