Khan, Sarif

[["dc.bibliographiccitation.artnumber","598"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","The European Physical Journal C"],["dc.bibliographiccitation.volume","81"],["dc.contributor.author","Khan, Sarif"],["dc.date.accessioned","2021-09-01T06:38:30Z"],["dc.date.accessioned","2022-08-18T12:28:16Z"],["dc.date.available","2021-09-01T06:38:30Z"],["dc.date.available","2022-08-18T12:28:16Z"],["dc.date.issued","2021-07-09"],["dc.date.updated","2022-07-29T10:06:25Z"],["dc.description.abstract","Abstract\r\n In the present work, we have extended the standard model by an abelian \r\n \r\n \r\n \r\n $U(1)_{X}$\r\n \r\n \r\n U\r\n \r\n \r\n (\r\n 1\r\n )\r\n \r\n X\r\n \r\n \r\n \r\n gauge group and additional particles. In particular, we have extended the particle content by three right handed neutrinos, two singlet scalars and two vectors like leptons. Charged assignments under different gauge groups are such that the model is gauge anomaly free and the anomaly contributions cancel among generations. Once the symmetry gets broken then three physical Higgses are produced, one axion like particle (ALP), which also acts as the keV scale FIMP dark matter is produced and the remaining component is absorbed by the extra gauge boson. Firstly, we have successfully generated neutrino mass by the type-I seesaw mechanism for normal hierarchy with the \r\n \r\n \r\n \r\n $3\\sigma $\r\n \r\n \r\n 3\r\n σ\r\n \r\n \r\n bound on the oscillation parameters. The ALP in the present model can explain the Xenon-1T electron recoil signal at keV scale through its coupling with the electron. We have shown that ALP can be produced from the right handed neutrino decay through the freeze in mechanism. Electron and tauon get masses from dimensional-5 operators at the Planck scale and if we consider the vevs \r\n \r\n \r\n \r\n $v_{1,2} \\simeq 10^{12}$\r\n \r\n \r\n \r\n v\r\n \r\n 1\r\n ,\r\n 2\r\n \r\n \r\n ≃\r\n \r\n 10\r\n 12\r\n \r\n \r\n \r\n GeV then we can obtain the correct value of the electron mass but not the tauon mass. The vector like leptons help in getting the correct value of the tauon mass through another higher dimensional operator which also has a role in DM production by the \r\n \r\n \r\n \r\n $2 \\rightarrow 2$\r\n \r\n \r\n 2\r\n →\r\n 2\r\n \r\n \r\n process, giving the correct ballpark value of relic density for suitable reheat temperature of the Universe. We have shown that the ALP production by the higher dimensional operator can explain the electron, tauon mass and Xenon-1T signal simultaneously whereas the decay production can not explain all of them together."],["dc.identifier.citation","The European Physical Journal C. 2021 Jul 09;81(7):598"],["dc.identifier.doi","10.1140/epjc/s10052-021-09397-x"],["dc.identifier.pii","9397"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/88945"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/112869"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-455"],["dc.publisher","Springer Berlin Heidelberg"],["dc.relation.eissn","1434-6052"],["dc.relation.issn","1434-6044"],["dc.rights.holder","The Author(s)"],["dc.title","Explaining Xenon-1T signal with FIMP dark matter and neutrino mass in a $U(1)_{X}$ extension"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","133"],["dc.bibliographiccitation.issue","11"],["dc.bibliographiccitation.journal","Journal of High Energy Physics"],["dc.bibliographiccitation.volume","2022"],["dc.contributor.author","Bélanger, Geneviève"],["dc.contributor.author","Choubey, Sandhya"],["dc.contributor.author","Godbole, Rohini M."],["dc.contributor.author","Khan, Sarif"],["dc.contributor.author","Mitra, Manimala"],["dc.contributor.author","Roy, Abhishek"],["dc.date.accessioned","2022-11-28T11:27:37Z"],["dc.date.available","2022-11-28T11:27:37Z"],["dc.date.issued","2022-11-23"],["dc.date.updated","2022-11-28T08:12:54Z"],["dc.description.abstract","Abstract\n \n We present an extension of the SM involving three triplet fermions, one triplet scalar and one singlet fermion, which can explain both neutrino masses and dark matter. One triplet of fermions and the singlet are odd under a Z2 symmetry, thus the model features two possible dark matter candidates. The two remaining Z2-even triplet fermions can reproduce the neutrino masses and oscillation parameters consistent with observations. We consider the case where the singlet has feeble couplings while the triplet is weakly interacting and investigate the different possibilities for reproducing the observed dark matter relic density. This includes production of the triplet WIMP from freeze-out and from decay of the singlet as well as freeze-in production of the singlet from decay of particles that belong to the thermal bath or are thermally decoupled. While freeze-in production is usually dominated by decay processes, we also show cases where the annihilation of bath particles give substantial contribution to the final relic density. This occurs when the new scalars are below the TeV scale, thus in the reach of the LHC. The next-to-lightest odd particle can be long-lived and can alter the successful BBN predictions for the abundance of light elements, these constraints are relevant in both the scenarios where the singlet or the triplet are the long-lived particle. In the case where the triplet is the DM, the model is subject to constraints from ongoing direct, indirect and collider experiments. When the singlet is the DM, the triplet which is the next-to-lightest odd particle can be long-lived and can be probed at the proposed MATHUSLA detector. Finally we also address the detection prospects of triplet fermions and scalars at the LHC."],["dc.identifier.citation","Journal of High Energy Physics. 2022 Nov 23;2022(11):133"],["dc.identifier.doi","10.1007/JHEP11(2022)133"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/117765"],["dc.language.iso","en"],["dc.publisher","Springer Berlin Heidelberg"],["dc.rights.holder","The Author(s)"],["dc.subject","Models for Dark Matter"],["dc.subject","Particle Nature of Dark Matter"],["dc.title","WIMP and FIMP dark matter in singlet-triplet fermionic model"],["dc.type","journal_article"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","064"],["dc.bibliographiccitation.issue","09"],["dc.bibliographiccitation.journal","Journal of Cosmology and Astroparticle Physics"],["dc.bibliographiccitation.volume","2022"],["dc.contributor.affiliation","Covi, Laura;"],["dc.contributor.affiliation","Khan, Sarif;"],["dc.contributor.author","Covi, Laura"],["dc.contributor.author","Khan, Sarif"],["dc.date.accessioned","2022-12-01T08:31:05Z"],["dc.date.available","2022-12-01T08:31:05Z"],["dc.date.issued","2022"],["dc.date.updated","2022-11-11T13:13:20Z"],["dc.description.abstract","Abstract\r\n \r\n In the Standard Model a Dark Matter candidate is missing, but it is relatively\r\n simple to enlarge the model including one or more suitable particles.\r\n We consider in this paper one such extension, inspired by simplicity and\r\n by the goal to solve more than just the Dark Matter issue.\r\n Indeed we consider a local U(1) extension of the SM providing an\r\n axion particle to solve the strong CP problem and including RH neutrinos\r\n with appropriate mass terms. One of the latter is decoupled from the SM\r\n leptons and can constitute stable sterile neutrino DM.\r\n In this setting, the PQ symmetry arises only as an accidental symmetry\r\n but its breaking by higher order operators is sufficiently suppressed to\r\n avoid introducing a large\r\n θ\r\n contribution.\r\n The axion decay constant and the RH neutrino masses are related\r\n to the same v.e.v.s and the PQ scale and both DM densities are determined by\r\n the parameters of the axion and scalar sector.\r\n The model predicts in general a mixed Dark Matter\r\n scenario with both axion and sterile neutrino DM and is characterised by\r\n a reduced density and observational signals from each single component."],["dc.identifier.doi","10.1088/1475-7516/2022/09/064"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/118070"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-621"],["dc.relation.eissn","1475-7516"],["dc.rights.uri","http://creativecommons.org/licenses/by/4.0/"],["dc.title","Axion and FIMP dark matter in a 𝖴(1) extension of the Standard Model"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","11"],["dc.bibliographiccitation.journal","Physical Review D"],["dc.bibliographiccitation.volume","99"],["dc.contributor.author","Dev, P. S. Bhupal"],["dc.contributor.author","Khan, Sarif"],["dc.contributor.author","Mitra, Manimala"],["dc.contributor.author","Rai, Santosh Kumar"],["dc.date.accessioned","2021-11-22T14:31:47Z"],["dc.date.available","2021-11-22T14:31:47Z"],["dc.date.issued","2019"],["dc.description.abstract","We explore the discovery prospect of the doubly-charged component of an SU(2)L-triplet scalar at the future e−p collider FCC-eh, proposed to operate with an electron beam energy of 60 GeV and a proton beam energy of 50 TeV. We consider the associated production of the doubly-charged Higgs boson along with leptons and jet(s), and its subsequent prompt decay to same-sign lepton pair. This occurs for O(1) Yukawa coupling of the scalar triplet with charged leptons, which is expected for reasonably small vacuum expectation values of the neutral component of the triplet field that governs the neutrino mass generation in the type-II seesaw. We present our analysis for two different final states, 3l+≥1j and an inclusive ≥2l+≥1j channel. Considering its decay to electrons only, we find that the doubly-charged Higgs boson with a mass around a TeV could be observed at the 3σ confidence level with O(200)  fb−1 of integrated luminosity, while masses up to 2 TeV could be probed within a few years of data accumulation. The signal proposed here becomes essentially background free, if it is triggered in the μμ mode and a 5σ discovery is achievable in this channel for a TeV-scale doubly-charged Higgs boson with an integrated luminosity as low as O(50)  fb−1. We also highlight the sensitivity of FCC-eh to the Yukawa coupling responsible for the production of the doubly-charged Higgs boson as a function of its mass in both the ee and μμ channels."],["dc.identifier.doi","10.1103/PhysRevD.99.115015"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16262"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/93402"],["dc.language.iso","en"],["dc.notes.intern","Migrated from goescholar"],["dc.relation","info:eu-repo/grantAgreement/EC/H2020/690575/EU//InvisiblesPlus"],["dc.relation.eissn","2470-0029"],["dc.relation.issn","2470-0010"],["dc.rights","CC BY 4.0"],["dc.rights.access","openAccess"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject","Doubly-charged Higgs boson; electron-proton collider"],["dc.subject.ddc","530"],["dc.title","Doubly-charged Higgs boson at a future electron-proton collider"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","193"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Journal of High Energy Physics"],["dc.bibliographiccitation.volume","2019"],["dc.contributor.author","Biswas, Anirban"],["dc.contributor.author","Choubey, Sandhya"],["dc.contributor.author","Covi, Laura"],["dc.contributor.author","Khan, Sarif"],["dc.date.accessioned","2021-11-22T14:31:46Z"],["dc.date.available","2021-11-22T14:31:46Z"],["dc.date.issued","2019"],["dc.description.abstract","In this work, we explain three beyond standard model (BSM) phenomena, namely neutrino masses, the baryon asymmetry of the Universe and Dark Matter, within a single model and in each explanation the right handed (RH) neutrinos play the prime role. Indeed by just introducing two RH neutrinos we can generate the neutrino masses by the Type-I seesaw mechanism. The baryon asymmetry of the Universe can arise from thermal leptogenesis from the decay of lightest RH neutrino before the decoupling of the electroweak sphaleron transitions, which redistribute the B − L number into a baryon number. At the same time, the decay of the RH neutrino can produce the Dark Matter (DM) as an asymmetric Dark Matter component. The source of CP violation in the two sectors is exactly the same, related to the complex couplings of the neutrinos. By determining the comoving number density for different values of the CP violation in the DM sector, we obtain a particular value of the DM mass after satisfying the relic density bound. We also give prediction for the DM direct detection (DD) in the near future by different ongoing DD experiments."],["dc.identifier.doi","10.1007/JHEP05(2019)193"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16224"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/93401"],["dc.language.iso","en"],["dc.notes.intern","Migrated from goescholar"],["dc.relation","info:eu-repo/grantAgreement/EC/H2020/690575/EU//InvisiblesPlus"],["dc.relation","info:eu-repo/grantAgreement/EC/H2020/674896/EU//ELUSIVES"],["dc.relation.eissn","1029-8479"],["dc.rights","CC BY 4.0"],["dc.rights.access","openAccess"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject","Cosmology of Theories beyond the SM; Neutrino Physics"],["dc.subject.ddc","530"],["dc.title","Common origin of baryon asymmetry, Dark Matter and neutrino mass"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","37"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Journal of High Energy Physics"],["dc.bibliographiccitation.volume","2022"],["dc.contributor.author","Biswas, Anirban"],["dc.contributor.author","Khan, Sarif"],["dc.date.accessioned","2022-08-04T12:00:08Z"],["dc.date.available","2022-08-04T12:00:08Z"],["dc.date.issued","2022-07-06"],["dc.date.updated","2022-07-25T11:18:47Z"],["dc.description.abstract","The quest for new physics beyond the Standard Model is boosted by the recently observed deviation in the anomalous magnetic moments of muon and electron from their respective theoretical prediction. In the present work, we have proposed a suitable extension of the minimal Lμ − Lτ model to address these two experimental results as the minimal model is unable to provide any realistic solution. In our model, a new Yukawa interaction involving first generation of leptons, a singlet vector like fermion (χ±) and a scalar (either an SU(2)L doublet Φ 4 ′ $ {\\Phi}_4^{\\prime } $ or a complex singlet Φ 4 ′ $ {\\Phi}_4^{\\prime } $ ) provides the additional one loop contribution to ae only on top of the usual contribution coming from the Lμ − Lτ gauge boson (Zμτ) to both electron and muon. The judicious choice of Lμ − Lτ charges to these new fields results in a strongly interacting scalar dark matter in O $ \\mathcal{O} $ (MeV) range after taking into account the bounds from relic density, unitarity and self interaction. The freeze-out dynamics of dark matter is greatly influenced by 3 → 2 scatterings while the kinetic equilibrium with the SM bath is ensured by 2 → 2 scatterings with neutrinos where Zμτ plays a pivotal role. The detection of dark matter is possible directly through scatterings with nuclei mediated by the SM Z bosons. Moreover, our proposed model can also be tested in the upcoming e+e− colliders by searching opposite sign di-electron and missing energy signal i.e. at the final state."],["dc.identifier.citation","Journal of High Energy Physics. 2022 Jul 06;2022(7):37"],["dc.identifier.doi","10.1007/JHEP07(2022)037"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/112642"],["dc.language.iso","en"],["dc.rights","CC BY 4.0"],["dc.rights.holder","The Author(s)"],["dc.subject","Cosmology of Theories BSM"],["dc.subject","Early Universe Particle Physics"],["dc.subject","Particle Nature of Dark Matter"],["dc.subject","Specific BSM Phenomenology"],["dc.title","(g − 2)e, μ and strongly interacting dark matter with collider implications"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Journal of High Energy Physics"],["dc.bibliographiccitation.volume","2019"],["dc.contributor.author","Abdallah, Waleed"],["dc.contributor.author","Choubey, Sandhya"],["dc.contributor.author","Khan, Sarif"],["dc.date.accessioned","2020-12-10T14:07:34Z"],["dc.date.available","2020-12-10T14:07:34Z"],["dc.date.issued","2019"],["dc.description.abstract","The non-thermal dark matter (DM) production via the so-called freeze-in mechanism provides a simple alternative to the standard thermal WIMP scenario. In this work, we consider a popular (1)_{B-L}$ extension of the standard model (SM) in the context of inverse seesaw mechanism which has at least one (fermionic) FIMP DM candidate. Due to the added $\\mathbb{Z}_{2}$ symmetry, a SM gauge singlet fermion, with mass of order keV, is stable and can be a warm DM candidate. Also, the same $\\mathbb{Z}_{2}$ symmetry helps the lightest right-handed neutrino, with mass of order GeV, to be a stable or long-lived particle by making a corresponding Yukawa coupling very small. This provides a possibility of a two component DM scenario as well. Firstly, in the absence of a GeV DM component (i.e., without tuning its corresponding Yukawa coupling to be very small), we consider only a keV DM as a single component DM, which is produced by the freeze-in mechanism via the decay of the extra '$ gauge boson associated to (1)_{B-L}$ and can consistently explain the DM relic density measurements. In contrast with most of the existing literature, we have found a reasonable DM production from the annihilation processes. After numerically studying the DM production, we show the dependence of the DM relic density as a function of its relevant free parameters. We use these results to obtain the parameter space regions that are compatible with the DM relic density bound. Secondly, we study a two component DM scenario and emphasize that the current DM relic density bound can be satisfied for a wide range of parameter space."],["dc.identifier.arxiv","1904.10015v2"],["dc.identifier.doi","10.1007/JHEP06(2019)095"],["dc.identifier.eissn","1029-8479"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16261"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/70241"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.relation.issn","1029-8479"],["dc.rights","CC BY 3.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/3.0/"],["dc.title","FIMP dark matter candidate(s) in a -L$ model with inverse seesaw mechanism"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","26"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Journal of High Energy Physics"],["dc.bibliographiccitation.volume","2022"],["dc.contributor.author","Costa, Francesco"],["dc.contributor.author","Khan, Sarif"],["dc.contributor.author","Kim, Jinsu"],["dc.date.accessioned","2022-06-17T12:40:57Z"],["dc.date.available","2022-06-17T12:40:57Z"],["dc.date.issued","2022-06-06"],["dc.date.updated","2022-06-17T08:03:23Z"],["dc.description.abstract","We consider an extension of the Standard Model that accounts for the muon g − 2 tension and neutrino masses and study in detail dark matter phenomenology. The model under consideration includes a WIMP and a FIMP scalar dark matter candidates and thus gives rise to two-component dark matter scenarios. We discuss different regimes and mechanisms of production, including the novel freeze-in semi-production, and show that the WIMP and FIMP together compose the observed relic density today. The presence of the extra scalar fields allows phase transitions of the first order. We examine the evolution of the vacuum state and discuss stochastic gravitational wave signals associated with the first-order phase transition. We show that the gravitational wave signals may be probed by future gravitational wave experiments which may serve as a complementary detection signal."],["dc.identifier.citation","Journal of High Energy Physics. 2022 Jun 06;2022(6):26"],["dc.identifier.doi","10.1007/JHEP06(2022)026"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/111435"],["dc.language.iso","en"],["dc.rights.holder","The Author(s)"],["dc.subject","Cosmology of Theories BSM"],["dc.subject","Models for Dark Matter"],["dc.subject","Particle Nature of Dark Matter"],["dc.subject","Phase Transitions in the Early Universe"],["dc.title","A two-component dark matter model and its associated gravitational waves"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]