arXiv subjects

Atanu Guha

Publications and source records attributed to Atanu Guha.

At least 19 recordsLinked to original sources

arXiv2026

Bayesian analysis of density profile of light dark matter elucidating the properties of dark matter admixed neutron stars in the presence of hyperons

We study the impact of symmetry energy ($S$), hyperons, and dark matter (DM) on structural and oscillatory properties of neutron stars (NSs). Uncertainty from hadronic equation of state for NSs is considered with 15 relativistic mean field models having slope parameter ($L_0$) of $S$ in range $40-120$ MeV. DM admixed NSs (DMANSs) are described with feeble interaction between light DM fermions ($\chi$) with hadronic matter in the presence of hyperons via scalar ($\eta$) and vector ($\xi$) dark mediators. The masses $m_{\chi}$, $m_{\eta}$ and $m_{\xi}$ are related by self-interaction constraints from bullet cluster. DM self-interaction couplings are related to $m_{\chi}$ by relic density constraint. The DM density is taken as an exponential function of baryon density with a free parameter $\alpha$. Uncertainty from DM model is incorporated by exploring the dependence on $m_{\chi}$ and $\alpha$. Several DM search experiments have almost ruled out the existence of massive DM ($\gtrsim$ GeV). Lately, pursuit for sub-GeV DM has attracted significant attention. Therefore, we consider $m_{\chi}<$ 1 GeV and $\alpha \leq$ 0.1 such that the contribution of DM to the total mass of the DMANSs is $<10\%$. Comparing our results with various astrophysical constraints, we find that the HESS J1731-347 and GW170817 data are very important in determining the presence of light DM in NSs in moderate amount, relevant in the range $L_0\lesssim$ 58 MeV. Employing models of DMANSs that satisfy several observational data, we infer with Bayesian analysis, the likely ranges of $m_{\chi}$ and $\alpha$ are almost independent of the underlying hadronic model within 40 MeV $\lesssim$ $L_0$ $<$ 58 MeV. In the absence of DM and with the most probable values of $m_{\chi}$ and $\alpha$ obtained from the Bayesian inference, we calculate the frequencies of non-radial $f$- and $p_1$-modes oscillation of NSs/DMANSs.

nucl-th↗

arXiv2025

A congruous approach with realistic cross section towards limiting sub-GeV dark matter from LUX-ZEPLIN

We present constraints on sub-GeV dark matter (DM) through the mechanism of being boosted by cosmic rays (CRs). We utilize the nuclear recoil data from the LUX-ZEPLIN (LZ) experiment for this purpose. Without the mechanism of boosted dark matter (BDM), sub-GeV DM particles are cold enough to produce detectable nuclear recoil in the LZ experiment above the detector threshold. We choose to work with the leading components of cosmic rays to take into account the boost due to them towards the cold DM. In the present discussion we worked on models consisting of a Dirac fermion $\chi$ with a new $U(1)'$ gauge symmetry and DM particles have non-zero coupling to the nucleons as per the model parameters. Specific examples of the energy dependence of the scattering cross section have been invoked through the secluded dark photon model and $U(1)_{B-L}$ model. Additionally, we present the upper bound on the interaction cross section due to the Earth shielding effect in the light of a systematic analysis of the energy loss by the BDM while traveling to the underground detector through the Earth's crust.

hep-ph↗

arXiv2025

Role of density profile of sub-GeV dark matter in the properties of dark matter admixed quark stars with Bayesian analysis of dark-NJL model

We investigate the structural and oscillation properties of dark matter (DM) admixed strange quark stars (DMSQSs). The strange quark matter (SQM) is described with the well-known Nambu-Jona-Lasino (NJL) model and the self-interacting fermionic DM is included in a systematic manner. The self-interaction of DM is of four-Fermi type and the overall DM density is considered as a function of the baryon density of SQM with two free parameters ($\alpha$, $\rho_{sc}$). This work is the first to consider four-Fermi interactions between fermionic DM and SQM in DMSQSs. Certain experiments like LZ, XENON, DarkSide, CRESST, and LHC have almost ruled out the possibility of contact interaction between SQM and massive DM (in GeV order). Recently, the quest for sub-GeV DM has garnered significant attention. We show that recent astrophysical constraints on the structural properties of compact stars also do not support the presence of massive DM in DMSQSs. On the other hand, we find sub-GeV DM to successfully concur with such observational constraints. We also calculate the fundamental $f$-mode frequency ($f_f$) of the DMSQSs, which shows universality with compactness, mean density, and tidal deformability. Further, we investigate the prospect of detection of $f_f$ with respect to the projected sensitivity of upcoming gravitational wave detectors like aLIGO, A+, Cosmic Explorer, and Einstein Telescope. In our DMSQS model, the three free parameters are $\alpha$, $\rho_{sc}$, and the ratio of repulsive to attractive interaction in SQM ($G_V/G_S$), which are optimized by Bayesian analysis in light of various recent astrophysical data.

hep-ph↗

arXiv2025

$f$ and $p$ mode oscillation of proto-neutron stars with systematic variation of the nucleon effective mass

We develop equation of state (EoS) of proto-neutron stars (PNSs) at various stages of evolution by varying entropy per baryon $S$, using the Korea-IBS-Daegu-SKKU density functional model. With finite values for both temperature and density, we systematically investigate the influence of nucleon effective mass on EoS of PNSs, for different values of isoscalar effective mass $\mu_S^*$. For high entropy values, we aim to replicate conditions of failed core-collapse supernovae forming black holes. At each stage of evolution, structural and non-radial oscillation (fundamental $f$-mode and first pressure $p_1$-mode) properties are computed under isentropic conditions by varying $\mu_S^*$. We focus on the effects of $S$ and $\mu_S^*$ on oscillation frequencies $f_f$ and $f_{p_1}$ adopting complete general relativistic formalism and Cowling approximation. Thermal effects reduce the values of $f_f$ and $f_{p_1}$ of PNSs compared to those of cold NSs, consequently detection of the former gets facilitated. For high-mass PNSs, this reduction is more pronounced for $f_{p_1}$ than $f_f$. Moreover, lower values of $\mu_S^*$ reduce $f_f$ and $f_{p_1}$ further. Universality of mass-scaled angular frequency ($\omega_fM$) with compactness ($C$) and tidal deformability ($\Lambda$) are obtained as non-linear fits that shift upwards (downwards) in $\omega_fM-C$ ($\omega_fM-\Lambda$) plane for increasing values of $S$. For fixed $S$, the universality is also retained for variation of $\mu_S^*$. $S$ shows stronger correlation than $\mu_S^*$ with structural and oscillation properties of (P)NSs. Strength of correlation of $S$ is more prominent with $f_{p_1}$ than $f_f$ while the trend is opposite for $\mu_S^*$. These findings suggest that detection of oscillation frequencies by upcoming GW detectors, could potentially indicate the evolutionary stage of a star during its transition from supernova to cold NS.

nucl-th↗

arXiv2024

Non-radial oscillations of hadronic neutron stars, quark stars, and hybrid stars : Calculation of $f$, $p$, and $g$ mode frequencies

The composition and equation of state (EoS) of dense matter relevant to compact stars are quite inconclusive. However, certain observational constraints on the structural properties of compact stars help us constrain the EoS to a fair extent. Moreover, gravitational asteroseismology gives a notion of the composition and EoS of compact stars. The next generation gravitational wave (GW) detectors are likely to detect several oscillation mode frequencies of the GWs. In this work we compute the fundamental ($f$) and the first pressure ($p_1$) mode frequencies ($f_f$ and $f_{p1}$, respectively) with different compositions viz., hadronic, quark, and hybrid star (HS) matter. For HSs, we also study the gravity ($g$) mode frequency ($f_g$). For each phase we also study the correlation between the oscillation frequencies of 1.4 $M_{\odot}$ and 2.01 $M_{\odot}$ compact stars with other different properties. We find that various possible composition of compact stars substantially affects the oscillation frequencies. However, the mass-scaled angular $f$ mode frequency ($\omega_f M$) varies universally with compactness ($C$) for all hadronic, quark and hybrid stars. The $f$ mode frequency ($f_{f_{1.4}}$) of the canonical 1.4 $M_{\odot}$ compact star, obtained with different composition, is quite correlated with the canonical radius ($R_{1.4}$) and tidal deformability ($\Lambda_{1.4}$) while $f_{p_{1.4}}$ is well correlated with slope parameter of the symmetry energy. We also show that $f_{g_{1.4}}$ of the HSs varies almost linearly with $\Lambda_{1.4}$. Should $g$ modes be detected, they could not only support the existence of HSs, but $f_g$ could be useful to understand the strength of quark repulsion in HSs.

hep-ph↗

arXiv2024

Effects of dark boson mediated feeble interaction between dark matter (DM) and quark matter on $f$-mode oscillation of DM admixed quark stars

We investigate the behavior of the prominent non-radial fundamental $f$-mode oscillations of dark matter (DM) admixed strange quark stars (DMSQSs), by adopting an equation of state (EoS) developed in Ref.~\cite{Sen:2022pfr}, which considers the possible presence of feebly interacting DM in strange quark stars (SQSs) for the first time. Within the model, feeble interaction between fermionic DM $\chi$ and strange quark matter (SQM) is invoked via a vector new physics mediator $\xi$ with coupling strength $y_{\xi}$. The pure SQM is described by the vector MIT Bag model. By varying different EoS parameters, the structural properties viz. the mass, radius and tidal deformability ($\Lambda$) of the DMSQSs are studied with respect to various astrophysical constraints. We study in detail the $f$-mode spectra within the Cowling approximation by obtaining the frequencies as a function of mass, compactness and $\Lambda$ of the star. To the best of our knowledge, this study represents the first analysis of non-radial $f$-mode oscillations of DMSQSs. Our investigation indicates that the presence of DM and its interaction with SQM has great impact on the $f$-modes. We show that the $f$-mode frequencies are larger for DMSQSs, which are largely populated with massive DM fermions, compared to the SQSs. Further, we obtain a linear empirical relation between the $f$-modes and the average density of the star. We also find that the mass-scaled angular frequency varies universally with compactness and $\ln{\Lambda}$ for DMSQSs. Further, our studies indicate that the inclusion of DM in compact stars reduces the deviation of $f$-mode frequency from general relativistic to Cowling approximation.

hep-ph↗

arXiv2024

Impact of dark boson mediated feeble interaction between dark matter and hadronic matter on $f$-mode oscillation of neutron stars

We studied the possible presence of dark matter (DM) in neutron stars (NSs) and the structural properties of the DM admixed NSs (DMANSs) in one of our recent works \cite{Guha:2024pnn}. The feeble interaction between the fermionic DM ($\chi$) with the hadronic matter is introduced through a dark scalar ($\phi$) and a dark vector ($\xi$) boson as mediators. The allowed range of the mass of the fermionic DM ($m_{\chi}$), for a particular range of DM Fermi momentum ($k_F^{\chi}$), was obtained in the same work \cite{Guha:2024pnn} with respect to the various astrophysical constraints on the structural properties of compact stars viz. the mass, radius and tidal deformability. The present work is dedicated to the calculation and study of non-radial oscillation of the DMANSs using Cowling approximation. We particularly investigate the effect of presence of DM on the fundamental ($f$) mode oscillation frequencies of the DMANSs utilizing the previously obtained range of $m_{\chi}$ for four different hadronic models. In this work we thoroughly investigate how the individual and combined effects of $m_{\chi}$ and $k_F^{\chi}$ affect the $f$-mode oscillation frequency. Within the framework of our DMANS models, for a particular value of $k_F^{\chi}$, the range of $f_{max}^{DMANS}$ with respect to the allowed range of $m_{\chi}$, is also obtained in the present work for four different hadronic models. Since in the present era, the 1.4 and 2.01 $M_{\odot}$ NSs are of special interest after the detection of GW170817 and PSR J0740+6620, we particularly investigate, for the four hadronic models, the range of $f_{1.4}^{DMANS}$ and $f_{2.01}^{DMANS}$ with respect to the acceptable range of $m_{\chi}$ corresponding to the range of $k_F^{\chi}$.

hep-ph↗

arXiv2024

Estimating the dark matter halo velocity and surface temperature of some known pulsars due to dark matter capture

Considering four known pulsars J1906+0746, J1933-6211, J2043+1711 and the Vela pulsar, we study the scenario of dark matter (DM) capture in neutron stars (NSs). For the purpose we choose four well-known relativistic mean field models to obtain the radius corresponding to the observed mass of these pulsars and consequently the scattering cross-section of DM with the different particles of the $\beta$ stable NS matter. The estimated DM-electron scattering cross-section in this work is stringent compared to the current direct detection experimental probe. We then compute the lower limit on the halo velocity of DM for the four pulsars from the knowledge of the upper limit on effective temperature of the individual pulsars. We also extend our work to calculate the value of the effective temperature with the different models using the fitted values of the halo velocity of DM of the four pulsars with respect to their distances from the galactic center. Our findings are consistent with the analysis of the observed data.

hep-ph↗

arXiv2024

Constraining the mass of fermionic dark matter from its feeble interaction with hadronic matter via dark mediators in neutron stars

Considering ten well-known relativistic mean field models, we invoke feeble interaction between hadronic matter and fermionic dark matter (DM) $\chi$ via new physics scalar ($\phi$) and vector ($\xi$) mediators in neutron star core, thereby forming DM admixed neutron stars (DMANSs). The chosen masses of the DM fermion ($m_{\chi}$) and the mediators ($m_{\phi}$ and $m_{\xi}$) are consistent with the self-interaction constraint from Bullet cluster while their respective couplings ($y_{\phi}$ and $y_{\xi}$) are also constrained by the present day relic abundance. Assuming that both $\phi$ and $\xi$ contribute equally to the relic abundance, we compute the equation of state of the DMANSs and consequently their structural properties. We found that for a particular (constant) DM density, the presence of lighter DM results in more massive DMANSs with larger radius. In the light of the various recent constraints like those from the massive pulsar PSR J0740+6620, the gravitational wave (GW170817) data and the results of NICER experiments for PSR J0030+0451 and PSR J0740+6620, we provide a bound on $m_{\chi}$ within the framework of the present work as $m_{\chi}\approx$ (0.1 $-$ 30) GeV for a wide range of fixed DM Fermi momenta $k_F^{\chi}$=(0.01 $-$ 0.07) GeV. In the case of the hadronic models that yield larger radii corresponding to the low mass neutron stars in the no-DM scenario, interaction with comparatively heavier DM fermion is necessary in order to ensure that the DMANSs obtained with such models satisfy the radius constraints from both GW170817 and NICER data for PSR J0030+0451.

astro-ph.HE↗

arXiv2024

Constraints on cosmic-ray boosted dark matter with realistic cross section

Sub-MeV cold dark-matter particles are unable to produce electronic recoil in conventional dark-matter direct detection experiments such as XENONnT and LUX-ZEPLIN above the detector threshold. The mechanism of boosted dark matter comes into picture to constrain the parameter space of such low mass dark matter from direct detection experiments. We consider the effect of the leading components of cosmic rays to boost the cold dark matter, which results in significant improvements on the exclusion limits compared to the existing ones. To present concrete study results, we choose to work on models consisting of a dark-matter particle $\chi$ with an additional $U(1)'$ gauge symmetry including the secluded dark photon, $U(1)_{B-L}$, and $U(1)_{L_e-L_\mu}$. We find that the energy dependence of the scattering cross section plays a crucial role in improving the constraints. In addition, we systematically estimate the Earth shielding effect on boosted dark matter in losing energy while traveling to the underground detector through the Earth.

hep-ph↗

arXiv2023

Inflation and the late time acceleration from Hossenfelder-Verlinde gravity

We show that Hossenfelder's covariant formulation of Verlinde's emergent gravity predicts inflation and the late-time acceleration at the same time, without assuming a separate field such as inflaton, whose sole purpose is producing inflation. In particular, for the current deceleration parameter $q=-0.95$ to $-0.55$, we obtained $\lambda^2$, the mass of the imposter field, from $1.85\times 10^4$ to $2.26\times 10^4$. We also note that the value of $\lambda$ around $q=-0.93$ coincides with the inverse of fine structure constant.

gr-qc↗

arXiv2022

Vector dark boson mediated feeble interaction between fermionic dark matter and strange quark matter in quark stars

We study the structural properties like the gravitational mass, radius and tidal deformability of dark matter (DM) admixed strange quark stars (SQSs). For the purpose we consider the vector MIT Bag model to describe the strange quark matter (SQM) and investigate the possible presence of accreted DM in the SQSs consequently forming DM admixed SQSs. We introduce feeble interaction between SQM and the accreted fermionic DM via a vector dark boson mediator. Considering the present literature, in the context of possible presence of DM in SQSs, this work is the first to consider interaction between DM and SQM in the DM admixed SQSs. The mass of the DM fermion ($m_{\chi}$) and the vector mediator ($m_{\xi}$) and the coupling ($y_{\xi}$) between them are determined in accordance with the constraint from Bullet cluster and the present day relic abundance, respectively. We find that the presence of DM reduces both the mass and radius of the star compared to the no-DM case. The massive the DM fermion, the lower the values of maximum mass and radius of the DM admixed SQSs. For the chosen values of $m_{\chi}$ and corresponding values of $m_{\xi}$ and $y_{\xi}$, the computed structural properties of the DM admixed SQSs satisfy all the various present day astrophysical constraints.We obtain massive DM admixed SQSs configurations consistent with the GW190814 observational data. Hence the secondary compact object associated with this event may be a DM admixed SQS.

hep-ph↗

arXiv2022

Bounds on boosted dark matter from direct detection: The role of energy-dependent cross sections

The recoil threshold of Direct Detection experiments limits the mass range of Dark Matter (DM) particles that can be detected, with most DD experiments being blind to sub-MeV DM particles. However, these light DM particles can be boosted to very high energies via collisions with energetic Cosmic Ray electrons. This allows Dark Matter particles to induce detectable recoil in the target of Direct Detection experiments. We derive constraints on scattering cross section of DM and electron, using XENONnT and Super-Kamiokande data. Vector and scalar mediators are considered, in the heavy and light regimes. We discuss the importance of including energy dependent cross sections (due to specific Lorentz structure of the vertex) in our analysis, and show that the bounds can be significantly different than the results obtained assuming constant energy-independent cross-section, often assumed in the literature for simplicity. Our bounds are also compared with other astrophysical and cosmological constraints.

hep-ph↗

arXiv2021

EFT analysis of leptophilic dark matter at future electron-positron colliders in the mono-photon and mono-$Z$ channels

We consider the possibility that dark matter (DM) only interacts with the Standard Model leptons, but not quarks at tree level, and analyze the future lepton collider prospects of such leptophilic DM in the monophoton and mono-$Z$ (both leptonic and hadronic) channels. Adopting a model-independent effective field theory framework, we consider all possible dimension-six operators of scalar-pseudoscalar (SP), vector-axial vector (VA), and tensor-axial tensor (TAT) types for a fermionic DM and derive the collider sensitivities on the effective cutoff scale $\Lambda$ as a function of the DM mass. As a concrete example, we take the beam configurations of the International Linear Collider with $\sqrt s=1$ TeV and $8$ ab$^{-1}$ integrated luminosity, including the effect of beam polarization, and show that it can probe leptophilic DM at $3\sigma$ level up to $\Lambda$ values of $6.6$, $8.8$, and $7.1$ TeV for the SP-, VA- and TAT-type operators, respectively. This is largely complementary to the direct and indirect searches for leptophilic DM and can potentially provide the best-ever sensitivity in the low-mass DM regime.

hep-ph↗

arXiv2021

Exclusion limits on Dark Matter-Neutrino Scattering Cross-section

We derive new constraints on combination of dark matter - electron cross-section ($\sigma_{\chi e}$) and dark matter - neutrino cross-section ($\sigma_{\chi \nu}$) utilising the gain in kinetic energy of the dark matter (DM) particles due to scattering with the cosmic ray electrons and the diffuse supernova neutrino background (DSNB). Since the flux of the DSNB neutrinos is comparable to the CR electron flux in the energy range $\sim 1\,{\rm MeV} - 50 \,{\rm MeV}$, scattering with the DSNB neutrinos can also boost low-mass DM significantly in addition to the boost due to interaction with the cosmic ray electrons. We use the XENON1T as well as the Super-Kamiokande data to derive bounds on $\sigma_{\chi e}$ and $\sigma_{\chi \nu}$. While our bounds for $\sigma_{\chi e}$ are comparable with those in the literature, we show that the Super-Kamiokande experiment provides the strongest constraint on $\sigma_{\chi \nu}$ for DM masses below a few MeV.

hep-ph↗

arXiv2021

Feeble DM-SM Interaction via New Scalar and Vector Mediators in Rotating Neutron Stars

We investigate the possible presence of dark matter (DM) in massive and rotating neutron stars (NSs). For the purpose we extend our previous work [1] to introduce a light new physics vector mediator besides a scalar one in order to ensure feeble interaction between fermionic DM and $\beta$ stable hadronic matter in NSs. The masses of DM fermion, the mediators and the couplings are chosen consistent with the self-interaction constraint from Bullet cluster and from present day relic abundance. Assuming that both the scalar and vector mediators contribute equally to the relic abundance, we compute the equation of state (EoS) of the DM admixed NSs to find that the present consideration of the vector new physics mediator do not bring any significant change to the EoS and static NS properties of DM admixed NSs compared to the case where only the scalar mediator was considered [1]. However, the obtained structural properties in static conditions are in good agreement with the various constraints on them from massive pulsars like PSR J0348+0432 and PSR J0740+6620, the gravitational wave (GW170817) data and the recently obtained results of NICER experiments for PSR J0030+0451 and PSR J0740+6620. We also extended our work to compute the rotational properties of DM admixed NSs rotating at different angular velocities. The present results in this regard suggest that the secondary component of GW190814 may be a rapidly rotating massive DM admixed NS. The constraints on rotational frequency from pulsars like PSR B1937+21 and PSR J1748-2446ad are also satisfied by our present results. Also, the constraints on moment of inertia are satisfied considering slow rotation. The universality relation in terms of normalized moment of inertia also holds good with our DM admixed EoS.

hep-ph↗

arXiv2021

Implications of Feebly Interacting Dark Sector on Neutron Star Properties and Constraints from GW170817

We investigate the effect of feeble interaction of dark matter (DM) with hadronic matter on the equation of state (EoS) and structural properties of neutron stars (NSs) in static conditions. For the purpose we adopt the effective chiral model for the hadronic sector and for the first time in the context of possible existence of DM inside NSs, we introduce DM-SM interaction through light new physics mediator. Moreover, the mass of DM fermion, the mediator and the coupling are adopted from the self-interaction constraint from Bullet cluster and from present day relic abundance. Within the considered framework, the work highlights the underlying stiffening of EoS in presence of DM fermion of mass of the order of a few GeV compared to the no-DM scenario. Consequently, the maximum gravitational mass of NS is obtained consistent with the bounds from the most massive pulsars which were not satisfied with the hadronic matter EoS alone. The estimates of radius and tidal deformability of 1.4 $M_{\odot}$ NS and the tidal deformabilities of the individual components of the binary neutron stars (BNS) associated with GW170817 are all in good agreement with the individual constraints obtained from GW170817 observation of BNS merger.

hep-ph↗

arXiv2018

Model-independent Astrophysical Constraints on Leptophilic Dark Matter in the Framework of Tsallis Statistics

We derive model-independent astrophysical constraints on leptophilic dark matter (DM), considering its thermal production in a supernova core and taking into account core temperature fluctuations within the framework of $q$-deformed Tsallis statistics. In an effective field theory approach, where the DM fermions interact with the Standard Model via dimension-six operators of either scalar-pseudoscalar, vector-axial vector, or tensor-axial tensor type, we obtain bounds on the effective cut-off scale $\Lambda$ from supernova cooling and free-streaming of DM from supernova core, and from thermal relic density considerations, depending on the DM mass and the $q$-deformation parameter. Using Raffelt's criterion on the energy loss rate from SN1987A, we obtain a lower bound on $\Lda \gtrsim 3$ (12) TeV corresponding to $q = 1.0~(1.1)$ and an average supernova core temperature of $T_{\rm SN}=30$ MeV. From the optical depth criterion on the free-streaming of DM fermions from the outer 10\% of the SN1987A core, the cooling bound is restricted to $\Lda \gtrsim 1$ TeV. Both cooling and free-streaming bounds are insensitive to the DM mass $m_\chi$ for $m_\chi\lesssim T_{\rm SN}$, whereas for $m_\chi\gg T_{\rm SN}$, the bounds weaken significantly due to the Boltzmann-suppression of the DM number density. We also calculate the thermal relic density of the DM particles in this setup and find that it imposes an upper bound on $\Lambda^4/m_\chi^2$, which together with the cooling/free-streaming bound significantly constrains light leptophilic DM.

hep-ph↗