arXiv subjects

Mansi Dhuria

Publications and source records attributed to Mansi Dhuria.

At least 19 recordsLinked to original sources

arXiv2026

Impact of Primordial Black Holes Induced Neutrinos on the Cosmic 21-cm Brightness Temperature

We study the impact of neutrinos emitted from evaporating Primordial Black Holes (PBHs) on the global 21-cm absorption signal during the dark ages and pre-reionization epochs. PBHs emit neutrinos over a wide energy range through Hawking evaporation. We investigate the possibility that radiative scattering between these neutrinos and the Cosmic Neutrino Background (C$\nu$B) generates secondary photons, leading to additional heating of the neutral hydrogen gas. This modifies the thermal history of the intergalactic medium and increases the global 21-cm brightness temperature relative to the standard cosmological prediction. Using the absorption feature at redshift $z\simeq17$, we derive new constraints on the PBH fraction for PBH masses in the range $10^{15}\mathrm{g}\lesssim m_{\rm BH,0}\lesssim10^{25}\mathrm{g}$. We further use existing PBH limits to constrain neutrino self-interaction couplings over a broad range of mediator masses. Our analysis complements previous studies that focused on direct photon injection from PBH evaporation and highlights the importance of neutrino-induced effects within a multimessenger framework for probing PBHs and beyond-standard-model neutrino interactions.

hep-ph↗

arXiv2025

KM3-230213A and IceCube Neutrino Events from Metastable Dark Matter of Primordial Black Hole Origin

We investigate a scenario in which the recently observed ultra-high-energy neutrino event KM3-230213A, with a median energy of approximately 220 PeV, as well as the high-energy neutrinos detected by IceCube Observatory, originate from the decay of superheavy dark matter (DM) particles produced through primordial black hole (PBH) evaporation. To establish this connection, we derive constraints on the PBH abundance parameter $\beta$ as a function of the initial PBH mass $M_{\mathrm{BH_0}}$ and DM mass $m_{\mathrm{DM}}$, by considering the bound from the observed relic DM abundance. Using these constraints, we compute the resulting neutrino flux and show that DM masses in the PeV-EeV range can yield neutrinos of comparable energies, capable of accounting for both the KM3-230213A and IceCube events while remaining consistent with the relic abundance constraint. Interestingly, the scenario remains viable over a broad region of parameter space while satisfying existing cosmological and astrophysical bounds. Overall, our results demonstrate that PBH evaporation followed by DM decay provides a consistent and natural explanation for the observed ultra-high-energy neutrino events in the absence of accompanying multimessenger signatures.

hep-ph↗

arXiv2024

Probing self-interacting ultrahigh-energy neutrinos with the cosmic 21-cm signal

In this study, we investigate the constraints on secret self-interactions of neutrinos by examining the impact of radiative scattering of ultrahigh-energy neutrinos. These neutrinos are produced from the decay of superheavy dark matter and interact with the cosmic neutrino background. We explore how these interactions influence the 21-cm hydrogen signal during the cosmic dark ages and cosmic dawn, periods relatively free from astrophysical uncertainties, providing a clearer signal for studying nonstandard neutrino interactions. By analyzing the global brightness temperature measurements, we constrain the scattering cross section of ultrahigh-energy self-interacting neutrinos, determining the coupling constant $g$ to be within $\sim 10^{-4}$ to $\sim 10^{-3}$ for neutrino energies in the PeV to EeV range. Interestingly, these constraints are more competitive than those from existing astrophysical and collider experiments. As future 21-cm experiments focus on measuring brightness temperature across a wide range of redshifts from the cosmic dark ages to reionization, using the epoch of 21-cm to probe neutrino properties could provide crucial insights into dark matter and neutrino physics.

hep-ph↗

arXiv2023

GRB221009A gamma-ray events from non-standard neutrino self-interactions

The flux of high-energy astrophysical neutrinos observed by the present generation of neutrino detectors has already indicated a few hints of new physics beyond the Standard Model. In this work, we show that high-energy gamma-ray observations can also be considered as a complementary probe for unveiling the source of high-energy astrophysical neutrino events and new physics. Recently, the LHAASO collaboration has reported O(5000) gamma-ray events in the energy range between 0.5 TeV -18 TeV from gamma-ray burst GRB221009A within 2000 seconds after the initial outburst. We showed that attenuated high-energy gamma rays can be produced from the interaction of astrophysical neutrinos with CMB neutrinos through non-standard self-interaction of neutrinos mediated by light scalar bosons. The non-standard interaction of neutrinos recently took a lot of attention in cosmology for its role in reducing Hubble tension. We have constrained the parameter space of non-standard self-interacting neutrinos from the flux of photons observed by LHAASO and showed consistency of the same with the resulting parameter space from Hubble tension requirements and other recent constraints from laboratory/cosmology.

hep-ph↗

arXiv2023

Synergy Between Hubble Tension Motivated Self-Interacting Neutrino and KeV-Sterile Neutrino Dark Matter

The discrepancy between the value of Hubble constant measured by CMB observations and local low-redshift based observations has proposed many solutions which require the existence of Physics beyond Standard Model (SM). One of the interesting solutions is based on considering the strong self-interaction between Standard Model (SM) neutrinos through an additional scalar/vector mediator. Interestingly, the strong self-interaction between SM neutrinos also play an important role in obtaining KeV-sterile neutrino as a viable Dark Matter (DM) candidate through the famous Dodelson-Widrow mechanism. In this work, we have tried to find the synergy between the parameter space of active-sterile neutrino mixing vs mass of sterile neutrino allowed by Hubble tension solution and the requirement of getting KeV-sterile neutrino as DM candidate. Interestingly, we get a large amount of parameter space that is consistent with both the requirements and also free from X-Ray constraints. Finally, we have embedded this scenario in a consistent supersymmetric model of particle physics. In this framework, we have shown that the value of sterile neutrino mass, SM neutrino mass and the required mixing angle can be naturally obtained by considering the supersymmetry breaking scale to be around O(10) TeV. Thus, it would give an interesting testing ground for supersymmetry as well as signatures of Warm Dark Matter (WDM).

hep-ph↗

arXiv2021

A strong broadband 21 cm cosmological signal from dark matter spin-flip interactions

In the standard cosmology, it is believed that there are two relatively weak and distinct band-limited absorption features, with the first absorption minima near 20 MHz ($z\sim70$) and the other minima at higher frequencies between 50-110 MHz ($z\sim12-27$) in the global cosmological 21cm signal, which are signatures of collisional gas dynamics in the cosmic dark ages and Lyman-$α$ photons from the first stars at cosmic dawn, respectively. A similar prediction of two distinct band-limited, but stronger, absorption features is expected in models with excess gas cooling, which have been invoked to explain the EDGES signal. In this work, we explore a novel mechanism, where dark matter spin-flip interactions with electrons through a light axial-vector mediator could directly induce a 21cm absorption signal which is characteristically different from either of these. We find generically, that our model predicts a strong, broadband absorption signal extending from frequencies as low as 1.4 MHz ($z\sim1000$), from early in the cosmic dark ages where no conventional signal is expected, all the way up to higher frequencies where star formation and X-ray heating effects are expected to terminate the absorption signal. In the standard cosmology and in excess gas cooling models it is expected that the gas spin temperature as inferred from the absorption signal is a tracer of the gas kinetic temperature. However, in our model we find in certain regions of parameter space that the spin temperature and kinetic temperature of the gas evolve differently, and the absorption signal only measures the spin temperature evolution. Large swathes of our model parameter space of interest are safe from existing constraints, however future searches for short range spin-dependent forces between electrons on the mm to nm scale have the potential to discover the light mediator responsible for our predicted signal.

astro-ph.CO↗

arXiv2020

Extracting the effective contact rate of COVID-19 pandemic

In the absence of any available vaccines or drugs, prevention of the spread of Coronavirus Disease 2019 (COVID-19) pandemic is being achieved by putting many mitigation measures in place. It is indispensable to have robust and reliable ways of evaluating the effectiveness of these measures. In this work, we assume that, at a very coarse-grained level of description, the overall effect of all the mitigation measures is that we can still describe the spread of the pandemic using the most basic Susceptible-Exposed-Infectious-Removed ($SEIR$) model but with an "effective contact rate" ($β$) which is time-dependent. We then use the time series data of the number of infected individuals in the population to extract the instantaneous effective contact rate which is the result of various social interventions put in place. This approach has the potential to be significantly useful while evaluating the impact of mitigation measures on the spread of COVID-19 in near future.

q-bio.PE↗

arXiv2019

Trans-Planckian Censorship Conjecture and Non-thermal post-inflationary history

The recently proposed Trans-Planckian Censorship Conjecture (TCC) can be used to constrain the energy scale of inflation. The conclusions however depend on the assumptions about post-inflationary history of the Universe. E.g. in the standard case of a thermal post-inflationary history in which the Universe stays radiation dominated at all times from the end of inflation to the epoch of radiation matter equality, TCC has been used to argue that the Hubble parameter during inflation, $H_{\inf}$, is below ${\cal O}(0.1) ~{\rm GeV}$. Cosmological scenarios with a non-thermal post-inflationary history are well-motivated alternatives to the standard picture and it is interesting to find out the possible constraints which TCC imposes on such scenarios. In this work, we find out the amount of enhancement of the TCC compatible bound on $H_{\inf}$ if post-inflationary history before nucleosynthesis was non-thermal. We then argue that if TCC is correct, for a large class of scenarios, it is not possible for the Universe to have undergone a phase of moduli domination.

astro-ph.CO↗

arXiv2019

Cosmology in the presence of multiple light moduli

The generic expectation in string/supergravity models is that there are multiple moduli fields with masses of the order of the supersymmetry breaking scale. We study the cosmology that arises as a result of vacuum misalignment of these moduli fields (in contrast to previous studies which mostly focussed on the single modulus case). We show that the dark radiation produced from the heavier moduli undergoes significant dilution. This happens even if there is a small splitting between the masses of the lightest and the heavier moduli. On the other hand, in the absence of fast annihilation processes decay of heavier moduli generically leads to overproduction of dark matter. We discuss a scenario where the problem can be addressed with a prompt dark matter annihilation to dark radiation. This can lead to realistic dark matter abundances, and the additional dark radiation produced as a result of this mechanism undergoes sufficient dilution as long as the annihilation is prompt.

hep-th↗

arXiv2018

Anomalous EDGES 21-cm Signal and Moduli Dominated Era

The EDGES collaboration has recently reported the detection of an unexpectedly stronger absorption signal in the global 21-cm spectrum around cosmic red-shift z = 17, resulting in the significant cooling of the primordial gas. The cooling of the gas can be expected to occur by considering the scattering off the baryons by a small fraction of DM carrying a tiny electromagnetic charge (milli-charged DM). However, it turns out the energy density of milli-charged DM obtained by considering thermal annihilation through massless photons will get overproduced in the range of parameters allowed by 21-cm line signal, if there are no new force carriers etc. In this study, we argue that the milli-charged DM particles might get decoupled during matter domination, in case there are moduli present in the theory. Therefore we estimated the value of relic abundance of milli-charged DM by taking into account an early matter dominated era. We found that for the value of modulus mass around m_Φ ~ 10^6TeV, the milli-charged DM particles could actually yield the desired fraction of DM particles for the values of charge and DM required to explain the 21-cm signal. Thus, the problem of an overproduction of the milli-charged DM density in the desirable range of mass and charge of DM can be evaded by considering an early moduli/matter dominated era.

hep-ph↗

arXiv2018

PeV scale Supersymmetry breaking and the IceCube neutrino flux

The observation of very high energy neutrino events at IceCube has grasped a lot of attention in the fields of both astrophysics and particle physics. It has been speculated that these high energy neutrinos might originate either from purely conventional astrophysical sources or from the late decay of a super heavy (PeV scale) dark matter (DM) particle. In order for decaying DM to be a dominant source of the IceCube high-energy neutrinos, it would require an unusually suppressed value of the coupling of DM to neutrinos. We attempt to explain this small coupling in the context of an $R$-parity conserving minimal supergravity model which has right-handed neutrino superfields. With the main assumptions of super-partner masses at the PeV scale and also a reheating temperature not much larger than the PeV scale, we find in our model several natural order-of-magnitude "miracles", (i) the gravitino is produced via freeze-in as a DM candidate with the correct relic density (ii) the right-handed (RH) sneutrino makes up only a tiny fraction ($10^{-6})$, of the present day energy density of the universe, yet its decay lifetime to the gravitino and neutrinos is such that it naturally predicts the right order-of-magnitude for the IceCube neutrino flux. The long lifetime of the RH sneutrino is explained by the existence of a global $R$-symmetry which is only broken due to supersymmetry breaking effects. Our model also predicts a flux of 100 TeV gamma rays from the decaying RH sneutrino which are within the current observational constraints.

hep-ph↗

arXiv2017

Extranatural Inflation Redux

The success of a given inflationary model crucially depends upon two features: its predictions for observables such as those of the Cosmic Microwave background (CMB) and its insensitivity to the unknown ultraviolet (UV) physics such as quantum gravitational effects. Extranatural inflation is a well motivated scenario which is insensitive to UV physics by construction. In this five dimensional model, the fifth dimension is compactified on a circle and the zero mode of the fifth component of a bulk $U(1)$ gauge field acts as the inflaton. In this work, we study simple variations of the minimal extranatural inflation model in order to improve its CMB predictions while retaining its numerous merits. We find that it is possible to obtain CMB predictions identical to those of e.g. ${\cal R} + {\cal R}^2$ Starobinsky model of inflation and show that this can be done in the most minimal way by having two additional extra light fermionic species in the bulk, with the same $U(1)$ charges. We then find the constraints that CMB observations impose on the parameters of the model.

hep-ph↗

arXiv2016

Perturbativity, vacuum stability and inflation in the light of 750 GeV diphoton excess

The recent observation of the 750 GeV diphoton excess at 13 TeV LHC has motivated many scenarios of physics beyond the Standard Model. In this work, we begin by showing that many models which explain the observed excess tend to get strongly coupled well below the Planck scale. We then study a simple scenario involving colored vector-like fermions with exotic charges, which is expected to stay weakly coupled till the Planck scale. We find the conditions under which this happens, derive the Renormalization Group equations for such models and solve them to show that perturbativity till Planck scale can be maintained for a very reasonable choice of parameters. Finally, we discuss issues related to vacuum stability and the possibility of inflation in the scenarios we study.

hep-ph↗

arXiv2015

Transport Coefficients of Black MQGP M3-Branes

The SYZ mirror, in the `delocalized limit' of [1], of (M)N (fractional)D3-branes, and wrapped N_f flavor D7-branes in the presence of a black-hole resulting in a non-Kaehler resolved warped deformed conifold (NKRWDC) in [2], was carried out in [3] and resulted in black M3-branes. The uplift, if valid globally(like [4] for fractional D3 branes in conifolds), asymptotes to M5-branes wrapping a two-cycle (homologously an (large) integer sum of two-spheres) in AdS_5xM_6. Interestingly, in the MQGP limit, assuming the deformation > resolution, by estimating the five SU(3) structure torsion (τ) classes W_{1,2,3,4,5} we show that τ\in W_4+W_5: 2/3 Re(W^3bar_5)=W^3bar_4 in the UV, implying the NKRWDC locally preserves SUSY. Further, the local T^3 of [3] in the large-r limit and the `MQGP' limit of [3], satisfies the same conditions as the maximal T^2-invariant special Lagrangian three-cycle of T^*(S^3) of [6], partly justifying use of local SYZ mirror symmetry in [3]. Using the Ouyang embedding in the DBI action of a D7-brane or by dimensionally reducing the 11-dimensional EH action to five (R^{1,3},r) dimensions, we then calculate a variety of gauge and metric-perturbation-modes' two-point functions using the prescription of [5], and show: (i) diffusion constant D~1/T, (ii) the electrical conductivity σ~T, (iii) the charge susceptibility χ~ T^2, (iv) [using (i) - (iii)] the Einstein's relation σ/χ=D, is indeed satisfied, (v) the R-charge diffusion constant D_R~1/T, and (vi) the possibility of generating η/s=1/4pi from solutions to the vector and tensor mode metric perturbations' EOMs, separately. All results are also valid in the limit of [2].

hep-th↗

arXiv2015

Falsifying leptogenesis for a TeV scale $W^{\pm}_{R}$ at the LHC

We point out that the discovery of a right-handed charged gauge boson $W_R^\pm$ with mass of around a few TeV, for example through a signal of two leptons and two jets that has been reported by CMS to have a 2.8$σ$ local excess or through a signal of a resonance decaying into a pair of standard model (SM) gauge bosons showing a local excess of 3.4$σ$ (2.5$σ$ global) reported by ATLAS search, will rule out all possibilities of leptogenesis in all classes of the left-right symmetric extensions of the Standard Model (LRSM) with both triplet and doublet Higgs scalars due to the unavoidable fast gauge mediated $B-L$ violating interactions $e_{R}^{\pm} W_{R}^{\mp} \rightarrow e_{R}^{\mp} W_{R}^{\pm}$. Our conclusions are very general in the sense that they do not necessarily demand for a lepton number violating detection signal of $W_R^\pm$.

hep-ph↗

arXiv2015

Moduli induced cogenesis of baryon asymmetry and dark matter

We study a cogenesis mechanism in which the observed baryon asymmetry of the universe and the dark matter abundance can be produced simultaneously at low reheating temperature without violating baryon number in the fundamental vertex. In particular, we consider a model which could be realized in the context of type IIB large volume string compactifications. The matter superfields in this model include additional pairs of color triplet and singlet superfields in addition to the Minimal Supersymmetric Standard Model (MSSM) superfields. Assuming that the mass of the additional singlet fermions is O(GeV) and color triplet fermions is O(TeV), we show that the modulus dominantly decays into the additional color triplet superfields. After soft supersymmetry (SUSY) breaking, the lightest eigenstate of scalar component of color triplet superfield further decays into fermionic component of singlet superfield and quarks without violating baryon number. Assuming R-parity conservation, it follows that the singlet superfield will not further decay into the SM particles and therefore it can be considered as a stable asymmetric dark matter (ADM) component. We find that the decay of the lightest eigenstate of scalar component of color triplet superfield gives the observed baryon asymmetry in the visible sector, an asymmetric dark matter component with the right abundance and naturally explains cosmic coincidence.

hep-ph↗

arXiv2015

Explaining the CMS excesses, baryogenesis and neutrino masses in $E_{6}$ motivated $U(1)_{N}$ model

We study the superstring inspired $E_{6}$ model motivated $U(1)_{N}$ extension of the supersymmetric standard model to explore the possibility of explaining the recent excess CMS events and the baryon asymmetry of the universe in eight possible variants of the model. In light of the hints from short-baseline neutrino experiments at the existence of one or more light sterile neutrinos, we also study the neutrino mass matrices dictated by the field assignments and the discrete symmetries in these variants. We find that all the variants can explain the excess CMS events via the exotic slepton decay, while for a standard choice of the discrete symmetry four of the variants have the feature of allowing high scale baryogenesis (leptogenesis). For one other variant three body decay induced soft baryogenesis mechanism is possible which can induce baryon number violating neutron-antineutron oscillation. We also point out a new discrete symmetry which has the feature of ensuring proton stability and forbidding tree level flavor changing neutral current processes while allowing for the possibility of high scale leptogenesis for two of the variants. On the other hand, neutrino mass matrix of the $U(1)_{N}$ model variants naturally accommodates three active and two sterile neutrinos which acquire masses through their mixing with extra neutral fermions giving rise to interesting textures for neutrino masses.

hep-ph↗

arXiv2015

The $eejj$ Excess Signal at the LHC and Constraints on Leptogenesis

We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy $E_6$-based models to investigate if they can explain both the recently detected excess $eejj$ signal at CMS and leptogenesis. The $eejj$ excess can be explained from the decay of the right-handed gauge bosons ($W_R$) with mass $\sim \rm{TeV}$ in certain variants of the LRSM (with $g_{L}\neq g_{R}$). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the $W_{R}$ mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the context of the LRSM for relatively large Yukawa couplings. However this may not be feasible due to washout of the lepton asymmetry by certain processes. Therefore we consider three effective low energy subgroups of the superstring inspired $E_{6}$ model having a number of additional exotic fermions which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of $E_6$ too cannot explain both the $eejj$ excess signal and leptogenesis simultaneously.

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