arXiv subjects

Prasanta Kumar Das

Publications and source records attributed to Prasanta Kumar Das.

At least 37 records · Page 2Linked to original sources

arXiv2022

Emergent Cosmology in Models of Nonlinear Electrodynamics

Nonlinear electrodynamics, which acts as a source of gravity Einstein field equations, leads to emergent cosmology, an alternative solution which can avoid Big Bang singularity. In this paper, we explore the emerging universe in models of non-linear electrodynamics (described by dimensional parameter $β$) by using the equation of state parameter $ω$ and see how the parameter $β$ helps the universe to cause a transition from a quasi-static Minkowski phase to the inflationary phase of expansion through the point of emergence and subsequently to the phase of normal thermal expansion. We predict the spectral index parameter $n_s = 0.97467$ (scalar spectral index), $r =0.10133$ (tensor to scalar ratio) and $n_T = -0.01267$ (tensor spectral index) of the inflationary perturbation in emergent cosmology of nonlinear electrodynamics corresponding to $β$ = 0.1 and $B_0=10^{-10}$G.

gr-qc↗

arXiv2020

Inflationary cosmology- A new approach using Non-linear electrodynamics

We explore a new kind of field of nonlinear electrodynamics(NLED) which acts as a source of gravity and can accelerate the universe during the inflationary era. We propose a new type of NLED lagrangian which is charecterized by two paremetrs $α$ and $β$. We investigate the classical stability and causality aspects of this model by demanding that the speed ($C_s = \frac{dP}{dρ}$) of the sound wave $C_s^2 > 0$ and $C_s \le 1$ and find that $0 < C_s^2 < 1$ corresponds to $0.25 \le α\le 0.4$ and $0.6 \le βB^2 \le 1$. A study of the deceleration parameter($q = \frac{1}{2}(1 + 3 ω)$, $ω= P/ρ$ being the equation of state parameter) suggests that the value $q < 0$ (i.e. $ω< -1/3$ and $\ddot{a}(t) > 0$ ( the accelerating universe)) requires $βB^2 \ge 0.13$. During inflation, the energy density $ρ_B$ is found to be maximum and is given by $ρ_B^{max} = 0.65/β$ corresponding to $α= 0.3$. The magnetic field necessary to trigger the inflation, is found to be $B (= B_{max}) \simeq \sqrt{\frac{0.4 ρ_B^{max}}{0.65}} = 4 \times 10^{51}~{\rm Gauss}$, where $ρ_{B}^{max}( =10^{64}~{\rm GeV}^4 $) is the energy density of the universe during inflation. The model also predict the e-fold number $N = 71$, which agrees with the experimental result.

hep-ph↗

arXiv2019

Inferring the covariant $Θ$-exact noncommutative coupling in the top quark pair production at linear colliders

A novel non-minimal interaction of neutral right-handed fermion and abelian gauge field in the covariant $Θ$-exact noncommutative standard model (NCSM) which is invariant under Very Special Relativity (VSR) Lorentz subgroup, opens an avenue to study the top quark pair production at linear colliders. Here the coupling denoted as $κ$ and the noncommutative (NC) scale $Λ$. In this work, we consider two types of analysis, one is without considering helicity basis and another, considering helicity states of the polarized and unpolarized initial and final particles. In the first case, when $κ$ is positive and for certain values of $Λ$, we arrived a specific threshold value of machine energy (units of GeV) $\sqrt{s_0}$ ($ \simeq 2.52 ~Λ+ 39$ ) may be quite useful to probe NCSM with the unpolarized beam. The statistical $χ^2$ analysis of the azimuthal anisotropy is quite possible when $κ$ takes negative value $0 >κ> -0.596$ which persuade a lower limit on NC scale $Λ$ ($ 1.0\, \text{to} \, 2.4\,\text{TeV}$) at $κ_{max}=-0.296 (95\%$ C.L) according to luminosity ranging from $100\,fb^{-1} \text{to}1000\,fb^{-1}$ at machine energy $\sqrt{s}=1.4\,\text{TeV}\,\text{and}\, 3.0\,\text{TeV}$. In another case, we performed polarized beam analysis to probe NCSM in the light of following observables azimuthal anisotropy, helicity correlation, and top quark helicity left-right asymmetry. The polarization of the initial beam $\{ P_{e^{-}},P_{e^{+}}\} = \{-0.8,0.3\}( \{-0.8,0.6\})$ enhances the ranges of lower limit on $Λ$, $i.e.\, 1.13 \, \text{to} \, 2.80\,\text{TeV}$ at $κ_{max}$ alongside the $κ_{max}$ enhanced into $-0.5445 \,(-0.607)$ $95\%$C.L accord with luminosity and $\sqrt{s}$. Finally, we studied the intriguing mixing of the UV and the IR by invoking $T(2)$ VSR Lorentz subgroup symmetry on NC tensor $Θ_{μν}$.

hep-ph↗

arXiv2019

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 $Λ$ 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 $m_χ$ for $m_χ\lesssim T_{\rm SN}$, whereas for $m_χ\gg T_{\rm SN}$, 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 $Λ^4/m_χ^2$, which together with the cooling/free-streaming bound significantly constrains light leptophilic DM.

hep-ph↗

arXiv2018

Constraints on light Dark Matter fermions from relic density consideration and Tsallis statistics

The cold dark matter fermions with mass MeV scale, pair produced inside the supernova SN1987A core, can freely stream away from the supernovae and hence contributes to its energy loss rate. Similar type of DM fermions(having similar kind of coupling to the standard model photon), produced from some other sources earlier, could have contributed to the relic density of the Universe. Working in a theory with an effective dark matter-photon coupling (inversely proportional to the scale $Λ$) in the formalism of Tsallis statistics, we find the dark matter contribution to the relic density and obtain a upper bound on $Λ$ using the experimental bound on the relic density for cold non-baryonic matter i.e. $Ωh^2 = 0.1186 \pm 0.0020 $. The upper bound obtained from the relic density is shown with the lower bound obtained from the Raffelt's criterion on the emissibity rate of the supernovae SN1987A energy loss $\dot{\varepsilon}(e^+ e^- \to χ\overlineχ) \le 10^{19}~\rm{erg~g^{-1}s^{-1}}$ and the optical depth criteria on the free streaming of the dark matter fermion (produced inside the supernovae core). As the deformation parameter $q$ changes from $1.0$ (undeformed scenario) to $1.1$(deformed scenario), the relic density bound on $Λ$ is found to vary from $ \sim 4.9 \times 10^7 $ TeV to $1.6 \times 10^8$ TeV for a fermion dark matter($χ$) of mass $m_χ= 30~\rm{MeV}$, which is almost $10$ times more than the lower bound obtained from the SN1987A energy loss rate and the optical depth criteria. \noindent {{\bf Keywords}: Dark matter, Relic density, Supernova cooling, Tsallis statistics, free-streaming, } }

hep-ph↗

arXiv2018

An Extensive Study of Bose-Einstein Condensation in Liquid Helium using Tsallis Statistics

Realistic scenario can be represented by general canonical ensemble way better than the ideal one, with proper parameter sets involved. We study the Bose-Einstein condensation phenomena of liquid helium within the framework of Tsallis statistics. With a comparatively high value of the deformation parameter $q(\sim 1.4)$, the theoretically calculated value of the critical temperature($T_c$) of the phase transition of liquid helium is found to agree with the experimentally determined value ($T_c = 2.17~\rm{K}$), although they differs from each other for $q=1$ (undeformed scenario). This throws a light on the understanding of the phenomenon and connects temperature fluctuation(non-equilibrium conditions) with the interactions between atoms qualitatively. More interactions between atoms give rise to more non-equilibrium conditions which is as expected. \noindent {{\bf Keywords}: Tsallis statistics, Bose-Einstein condensation, liquid helium.}

cond-mat.stat-mech↗

arXiv2017

$q$-deformed Einstein's Model to Describe Specific Heat of Solid

Realistic phenomena can be described more appropriately using generalized canonical ensemble, with proper parameter sets involved. We have generalized the Einstein's theory for specific heat of solid in Tsallis statistics, where the temperature fluctuation is introduced into the theory via the fluctuation parameter $q$. At low temperature the Einstein's curve of the specific heat in the nonextensive Tsallis scenario exactly lies on the experimental data points. Consequently this $q$-modified Einstein's curve is found to be overlapping with the one predicted by Debye. Considering only the temperature fluctuation effect(even without considering more than one mode of vibration is being triggered) we found that the $C_V$ vs $T$ curve is as good as obtained by considering the different modes of vibration as suggested by Debye. Generalizing the Einstein's theory in Tsallis statistics we found that a unique value of the Einstein temperature $θ_E$ along with a temperature dependent deformation parameter $q(T)$, can well describe the phenomena of specific heat of solid i.e. the theory is equivalent to Debye's theory with a temperature dependent $θ_D$.

cond-mat.stat-mech↗

arXiv2017

Blackbody Radiation in $q$-deformed Statistics

More general canonical ensemble which gives rise the generalized statistics or $q$-deformed statistics can represent the realistic scenario than the ideal one, with proper parameter sets involved. We study the Planck's law of blackbody radiation, Wein's and Rayleigh-Jeans radiation formulae from the point of view of $q$-deformed statistics. We find that the blackbody energy spectrum curve for a given temperature $T$ corresponding to different $q$ values differs from each other: the location of the peak(i.e. $ν_m$) of the energy distribution $u_ν$ (corresponding to different $q$ ) shifted towards higher $ν$ for higher $q$. From the $q$-deformed Wein's displacement law, we find that $λ_m T$ varies from $0.0029~\rm{m~K}$ to $0.0017~\rm{m~K}$ as the deformation parameter $q$ varies from $1.0$(undeformed) to $1.1$(deformed).

cond-mat.stat-mech↗

arXiv2016

q-deformed statistics and the role of a light fermionic dark matter in the supernova SN1987A cooling

Light dark matter($\simeq 1-30~\rm{MeV}$) particles pair produced in electron-positron annihilation $ e^-e^+ \stackrelγ{\longrightarrow} χ\barχ$ inside the supernova core can take away the energy released in the supernova SN1987A explosion. Working within the formalism of $q$-deformed statistics (with the average value of the supernovae core temperature(fluctuating) being $T_{SN} = 30~\rm{MeV}$) and using the Raffelt's criterion on the emissivity for any new channel $\dot{\varepsilon}(e^+ e^- \to χ\overlineχ) \le 10^{19}~{erg~g^{-1}s^{-1}}$, we find that as the deformation parameter $q$ changes from $1.0$ (undeformed scenario) to $1.1$(deformed scenario), the lower bound on the scale $Λ$ of the dark matter effective theory varies from $3.3\times 10^6$ TeV to $3.2 \times 10^7$ TeV for a dark matter fermion of mass $m_χ= 30~\rm{MeV}$. Using the optical depth criteria on the free streaming of the dark matter fermion, we find the lower bound on $Λ\sim 10^{8}~\rm{TeV}$ for $m_χ= 30~\rm{MeV}$. In a scenerio,where the dark matter fermions are pair produced in the outermost sector of the supernova core (with radius $0.9 R_c \le r \le R_c$, $R_c (=10~\rm{km})$ being the supernova core radius or the radius of proto-neutron star), we find that the bound on $Λ$ ($\sim 3 \times 10^7$ TeV)obtained from SN cooling criteria (Raffelt's criteria) is comparable with the bound obtained from free streaming (optical depth criterion) for light fermion dark matter of mass $m_χ=10 - 30$ MeV.

hep-ph↗

arXiv2016

Drell-Yan as an avenue to test noncommutative Standard Model at the Large Hadron Collider

We study the Drell-Yan process at the Large Hadron Collider in presence of the noncommutative extension of standard model. Using the Seiberg-Witten map, we calculate the production cross-section to the first order in the noncommutative parameter $Θ_{μν}$. Although this idea is evolving for long, limited amount of phenomenological analysis was done so far and dominantly in the context of linear collider. Some outstanding feature from this non-minimal noncommutative standard model not only modify the couplings over SM production channel, also allow additional nonstandard vertices which can play a significant role. Hence in the Drell-Yan process, as studied in present analysis, one also needs to account for gluon fusion process at the tree level. Some of the characteristic signatures such as oscillatory azimuthal distributions are outcome of the momentum dependent effective couplings. We explore the noncommutative scale $Λ_{NC} \ge 0.4~\rm{TeV}$ considering different machine energy ranging from $7~\rm{TeV}$ to $13~\rm{TeV}$.

hep-ph↗

arXiv2015

Search for associated production of Higgs with Z boson in the noncommutative Standard Model at linear colliders

We study the associated Higgs production with Z boson at future linear colliders in the framework of the minimal noncommutative standard model. Using the Seiberg-Witten map, we calculate the production cross-section considering all orders of the noncommutative parameter $Θ_{μν}$. We consider the effect of earth's rotation on the orientation of $Θ_{μν}$ with respect to the laboratory frame and thus on the total cross-section, it's azimuthal distribution and rapidity distribution for the machine energy ranging from 0.5 TeV to 3.0 TeV corresponding to the noncommutative scale $Λ\ge $ 0.5 TeV.

hep-ph↗

arXiv2012

Impact of a light stabilized radion in supernovae cooling

In the Randall-Sundrum model where the Standard Model fields are confined to the TeV brane located at the orbifold point $θ= π$ and the gravity peaks at the Planck brane located at $θ= 0$, the stabilized modulus (radion) field is required to stabilize the size of the fifth spatial dimension. It can be produced copiously inside the supernova core due to nucleon-nucleon bremstrahlung, electron-positron and plasmon-plasmon annihilations, which then subsequently decays to neutrino-antineutrino pair and take away the energy released in SN1987A explosion. Assuming that the supernovae cooling rate $\dot{\varepsilon} \le 7.288\times 10^{-27} \rm{GeV}$, we find the lower bound on the radion vev $\vphi \sim 9.0$ TeV, 2.2 TeV and 0.9 TeV corresponding to the radion mass $m_ϕ= 5$ GeV, 20 GeV and 50 GeV, respectively.

hep-ph↗

arXiv2012

Effect of earth rotation on pair production of Standard Model Higgs bosons at linear colliders in the noncommutative space-time

We study the neutral Higgs boson pair production through $e^{+} e^{-}$ collision in the noncommutative(NC) extension of the standard model using the Seiberg-Witten maps of this to the first order of the noncommutative parameter $Θ_{μν}$. This process is forbidden in the standard model at the tree level with background space-time being commutative. After including the effects of earth's rotation we analyse the time-averaged cross section of the pair production of Higgs boson (in the light of LEP II and LHC data) at the future Linear Collider which can be quite significant for the NC scale $Λ$ lying in the range $0.3 - 1.0$ TeV. For the 125 GeV Higgs mass(the most promising value of Higgs mass as reported by LHC), we find the NC scale as $330 \rm{GeV}$ $\le Λ\le 660 \rm{GeV}$ and using $m_h = 129(127.5) \rm{GeV}$ (the lower threshold value of the excluded region of $m_h$ reported by ATLAS(CMS) collaborations of LHC), we find the bound on $Λ$ as: (i) $339 (336) \rm{GeV} \le Λ\le 677 (670) \rm{GeV}$ corresponding to the Linear Collider energy $E_{com} = 500 \rm{GeV}$.

hep-ph↗

arXiv2012

Laboratory frame analysis of $e^+ e^- \to μ^+ μ^-$ scattering in the Noncommutative Standard Model

We study the muon pair production $ e^+ e^- \to μ^+ μ^-$ in the framework of the non-minimal noncommutative(NC) standard model to the second order of the NC parameter $Θ_{μν}$. The $\mathcal{O}(Θ^2)$ momentum dependent NC interaction significantly modifies the cross section and angular distributions which are different from the standard model. After including the effects of earth's rotation we analyse the time-averaged and time dependent observables in detail. The time-averaged azimuthal distribution of the cross section shows siginificant departure from the standard model. We find strong dependence of the total cross section(time- averaged) and their distributions on the orientation of the noncommutative electric vector (${\vecΘ}_E$). The periodic variation of the total cross-section with time over a day seems to be startling and can be thoroughly probed at the upcoming Linear Collider(LC).

hep-ph↗

arXiv2010

$e^+ e^- \to μ^+ μ^-$ scattering in the Noncommutative standard model

We study muon pair production $ e^+ e^- \to μ^+ μ^-$ in the noncommutative(NC) extension of the standard model using the Seiberg-Witten maps of this to the second order of the noncommutative parameter $Θ_{μν}$. Using $\mathcal{O}(Θ^2)$ Feynman rules, we find the $\mathcal{O}(Θ^4)$ cross section(with all other lower order contributions simply cancelled) for the pair production. The momentum dependent $\mathcal{O}(Θ^2)$ NC interaction significantly modifies the cross section and angular distributions which are different from the commuting standard model. We study the collider signatures of the space-time noncommutativity at the International Linear Collider(ILC) and find that the process $ e^+ e^- \to μ^+ μ^-$ can probe the NC scale $Λ$ in the range $0.8 - 1.0$ TeV for typical ILC energy ranges.

hep-ph↗

arXiv2010

Neutral Higgs boson pair production at the LC in the Noncommutative Standard Model

We study the Higgs boson pair production through $e^+e^-$ collision in the noncommutative(NC) extension of the standard model using the Seiberg-Witten maps of this to the first order of the noncommutative parameter $Θ_{μν}$. This process is forbidden in the standard model with background space-time being commutative. We find that the cross section of the pair production of Higgs boson (of intermediate and heavy mass) at the future Linear Collider(LC) can be quite significant for the NC scale $Λ$ lying in the range $0.5 - 1.0$ TeV. Finally, using the direct experimental(LEP II, Tevatron and global electro-weak fit) bound on Higgs mass, we obtain bounds on the NC scale as 665 GeV $\le Λ\le 998$ GeV.

hep-ph↗

arXiv2008

Implication of the HyperCP boson $X^0$ (214 MeV) in the flavour changing neutral current processes

We analyze the inclusive $b(c) \to s(u) μ^+ μ^-$ and the exclusive $B(D^+) \to K(π^+) μ^+ μ^-$ flavour changing neutral current decays in the light of HyperCP boson $X^0$ of mass 214 MeV recently observed in the hyperon decay $Σ^+ \to p μ^+ μ^-$. Using the branching ratio data of the above inclusive and exclusive decays, we obtain constraints on $g_1 (h_1)$ and $g_2 (h_2)$, the scalar and pseudo-scalar coupling constants of the $b-s-X^0 (c-u-X^0)$ vertices.

hep-ph↗

arXiv2008

Plasmon Annihilation into Kaluza-Klein Graviton: New Astrophysical Constraints on Large Extra Dimensions

In large extra dimensional Kaluza-Klein (KK) scenario, where the usual Standard Model (SM) matter is confined to a 3+1-dimensional hypersurface called the 3-brane and gravity can propagate to the bulk (D=4+d, d being the number of extra spatial dimensions), the light graviton KK modes can be produced inside the supernova core due to the usual nucleon-nucleon bremstrahlung, electron-positron and photon-photon annihilations. This photon inside the supernova becomes plasmon due to the plasma effect. In this paper, we study the energy-loss rate of SN 1987A due to the KK gravitons produced from the plasmon-plasmon annihilation. We find that the SN 1987A cooling rate leads to the conservative bound $M\_D$ > 22.9 TeV and 1.38 TeV for the case of two and three space-like extra dimensions.

hep-ph↗