arXiv subjects

P. S. Bhupal Dev

Publications and source records attributed to P. S. Bhupal Dev.

At least 73 records · Page 4Linked to original sources

arXiv2023

Hints of a new leptophilic Higgs sector?

We show that a new leptophilic Higgs sector can resolve some intriguing anomalies in current experimental data across multiple energy ranges. Motivated by the recent CMS excess in the resonant $eμ$ channel at 146 GeV, we focus on a leptophilic two-Higgs-doublet model, and propose a resonant production mechanism for the neutral components of the second Higgs doublet at the LHC using the lepton content of the proton. Interestingly, the same Yukawa coupling $Y_{eμ}\sim 0.6-0.8$ that explains the CMS excess also addresses the muon $(g-2)$ anomaly. Moreover, the new Higgs doublet also resolves the recent CDF $W$-boson mass anomaly. The relevant model parameter space will be completely probed by future LHC data.

hep-ph↗

arXiv2023

New Constraints on Axion-Like Particles from IXPE Polarization Data for Magnetars

We derive new constraints on axion-like particles (ALPs) using precision $X$-ray polarization studies of magnetars. Specifically, we use the first detection of polarized $X$-rays from the magnetars 4U 0142+61 and 1RXS J170849.0-400910 by the Imaging $X$-ray Polarimetry Explorer (IXPE) to place bounds on the product of the ALP-photon and ALP-nucleon couplings, $g_{aγ}g_{aN}$, with $g_{aN}$ being responsible for ALP production in the core of the magnetar and $g_{aγ}$ controlling the ALP-photon conversion probability in the magnetosphere. These bounds are most sensitive to the magnetar core temperature, and we use two benchmark values of $1\times 10^8$ K and $5\times 10^8$ K to derive our constraints. For the latter choice, our bounds are competitive with the existing bounds on the coupling product coming from a combination of CAST (for $g_{aγ}$) and SN1987A (for $g_{aN}$). We advocate for more precise and extensive observational campaigns in the higher end of the $2~-~8~$keV spectral window, where ALP-induced polarization is the strongest. We further advocate for hard $X$-ray polarization studies of young, hot, near-Earth magnetars with strong magnetic fields.

hep-ph↗

arXiv2023

Searching for Heavy Leptophilic $Z'$: from Lepton Colliders to Gravitational Waves

We study the phenomenology of leptophilic $Z'$ gauge bosons at the future high-energy $e^+e^-$ and $μ^+μ^-$ colliders, as well as at the gravitational wave observatories. The leptophilic $Z'$ model, although well-motivated, remains largely unconstrained from current low-energy and collider searches for $Z'$ masses above ${\cal O}(100~{\rm GeV})$, thus providing a unique opportunity for future lepton colliders. Taking $U(1)_{L_α-L_β}~(α,β=e,μ,τ)$ models as concrete examples, we show that future $e^+e^-$ and $μ^+μ^-$ colliders with multi-TeV center-of-mass energies provide unprecedented sensitivity to heavy leptophilic $Z'$ bosons. Moreover, if these $U(1)$ models are classically scale-invariant, the phase transition at the $U(1)$ symmetry-breaking scale tends to be strongly first-order with ultra-supercooling, and leads to observable stochastic gravitational wave signatures. We find that the future sensitivity of gravitational wave observatories, such as advanced LIGO-VIRGO and Cosmic Explorer, can be complementary to the collider experiments, probing higher $Z'$ masses up to ${\cal O}(10^4~{\rm TeV})$, while being consistent with naturalness and perturbativity considerations.

hep-ph↗

arXiv2023

Probing Freeze-in Dark Matter via Heavy Neutrino Portal

We explore the possibility of probing freeze-in dark matter (DM) produced via the right-handed neutrino (RHN) portal using the RHN search experiments. We focus on a simplified framework of minimally-extended type-I seesaw model consisting of only four free parameters, namely the RHN mass, the fermionic DM mass, the Yukawa coupling between the DM and the RHN, and a real singlet scalar mass. We consider two cases for the DM production either via decay of the thermal RHN or via scattering of the bath particles mediated by the RHN. In both cases, we show that for sub-TeV scale DM masses, the allowed model parameter space satisfying the observed DM relic density for freeze-in scenario falls within the reach of current and future collider, beam dump and forward physics facilities looking for feebly-coupled heavy neutrinos.

hep-ph↗

arXiv2023

Probing the muon (g-2) anomaly at the LHC in final states with two muons and two taus

The longstanding muon $(g-2)$ anomaly, as well as the persistent hints of lepton flavor universality violation in $B$-meson decays, could be signaling new physics beyond the Standard Model (SM). A minimal $R$-parity-violating supersymmetric framework with light third-generation sfermions (dubbed as 'RPV3') provides a compelling solution to these flavor anomalies, while simultaneously addressing other pressing issues of the SM. We propose a new RPV3 scenario for the solution of the muon $(g-2)$ anomaly, which leads to an interesting LHC signal of $μ^+μ^-τ^+τ^-$ final state. We analyze the Run-2 LHC multilepton data to derive stringent constraints on the sneutrino mass and the relevant RPV coupling in this scenario. We then propose dedicated selection strategies to improve the bound even with the existing dataset. We also show that the high-luminosity LHC will completely cover the remaining muon $(g-2)$-preferred parameter space, thus providing a robust, independent test of the muon $(g-2)$ anomaly.

hep-ph↗

arXiv2023

A New Probe of Relic Neutrino Clustering using Cosmogenic Neutrinos

We propose a new probe of cosmic relic neutrinos (C$ν$B) using their resonant scattering against cosmogenic neutrinos. Depending on the lightest neutrino mass and the energy spectrum of the cosmogenic neutrino flux, a Standard Model vector meson (such as a hadronic $ρ$) resonance can be produced via $ν\barν$ annihilation. This leads to a distinct absorption feature in the cosmogenic neutrino flux at an energy solely determined by the meson mass and the neutrino mass, apart from redshift. By numerical coincidence, the position of the $ρ$-resonance overlaps with the originally predicted peak of the Greisen-Zatsepin-Kuzmin (GZK) neutrino flux, which offers an enhanced absorption effect at higher redshifts. We show that this absorption feature in the GZK neutrino flux may be observable in future radio-based neutrino observatories, such as IceCube-Gen2 radio, provided there exists a large overdensity in the C$ν$B distribution. This therefore provides a new probe of C$ν$B clustering at large redshifts, complementary to the laboratory probes (such as KATRIN) at zero redshift.

hep-ph↗

arXiv2023

Probing the $ν_{R}$-philic $Z'$ at DUNE near detectors

We consider a hidden $U(1)$ gauge symmetry under which only the right-handed neutrinos ($ν_{R}$) are charged. The corresponding gauge boson is referred to as the $ν_{R}$-philic $Z'$. Despite the absence of direct gauge couplings to ordinary matter at tree level, loop-induced couplings of the $ν_{R}$-philic $Z'$ via left-right neutrino mixing can be responsible for its experimental accessibility. An important feature of the $ν_{R}$-philic $Z'$ is that its couplings to neutrinos are generally much larger than its couplings to charged leptons and quarks, thus providing a particularly interesting scenario for future neutrino experiments such as DUNE to probe. We consider two approaches to probe the $ν_{R}$-philic $Z'$ at DUNE near detectors via (i) searching for $Z'$ decay signals, and (ii) precision measurement of elastic neutrino-electron scattering mediated by the $Z'$ boson. We show that the former will have sensitivity comparable to or better than previous beam dump experiments, while the latter will improve current limits substantially for large neutrino couplings.

hep-ph↗

arXiv2023

Probing Pseudo-Dirac Neutrinos with Astrophysical Sources at IceCube

The recent observation of NGC 1068 by the IceCube Neutrino Observatory has opened a new window to neutrino physics with astrophysical baselines. In this Letter, we propose a new method to probe the nature of neutrino masses using these observations. In particular, our method enables searching for signatures of pseudo-Dirac neutrinos with mass-squared differences that reach down to $δm^2 \gtrsim 10^{-21}~\text{eV}^2$, improving the reach of terrestrial experiments by more than a billion. Finally, we discuss how the discovery of a constellation of neutrino sources can further increase the sensitivity and cover a wider range of $δm^2$ values.

astro-ph.HE↗

arXiv2023

Constraining Lepton Flavor Violating Higgs Couplings at the HL-LHC in the Vector Boson Fusion Channel

We explore the parameter space of lepton flavor violating (LFV) neutral Higgs Yukawa couplings with the muon and tau leptons that can be probed at the high-luminosity Large Hadron Collider (HL-LHC) via the vector boson fusion~(VBF) Higgs production process. Our projected sensitivities for the Standard Model Higgs ($h$) LFV branching ratio ${\rm Br}(h \to μτ)$ in the $pp \to h j j \to (h \to μτ) jj$ channel at the HL-LHC are contrasted with the current and future low-energy constraints from the anomalous magnetic moment and electric dipole moment of the muon, as well as with other LFV observables, such as $τ\to 3μ$ and $τ\to μγ$. We also study the LFV prospects of a generic beyond the Standard Model neutral Higgs boson ($H$) with a mass in the range of $m_{H}\in [20,800]~$GeV and give the projected model-independent upper limits on the VBF production cross-section of $Hjj$ times the branching ratio of $H\to μτ$ at the HL-LHC. We interpret these results in the context of a two-Higgs doublet model as a case study.

hep-ph↗

arXiv2022

Interplay between Resonant Leptogenesis, Neutrinoless Double Beta Decay and Collider Signals in a Model with Flavor and CP Symmetries

We present a low-scale type-I seesaw scenario with discrete flavor and CP symmetries. This scenario not only explains the measured values of the lepton mixing angles, but also makes predictions for leptonic CP violation, and connects the low-energy CP phases relevant for neutrino oscillation and neutrinoless double beta decay experiments with the high-energy CP phases relevant for leptogenesis. We show that the three right-handed Majorana neutrinos in this scenario have (almost) degenerate masses and their decays can explain the observed baryon asymmetry of the Universe via resonant leptogenesis. We study the correlation of the predicted baryon asymmetry with lepton-number-violating signals at high-energy colliders, including both prompt and displaced vertex/long-lived signatures, as well as in low-energy neutrinoless double beta decay experiments. We find that the normal ordering of light neutrino masses leads to an enhanced collider signal, whereas the neutrinoless double beta decay provides a promising probe in the inverted ordering case.

hep-ph↗

arXiv2022

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 $Λ$ 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 $3σ$ level up to $Λ$ 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↗

arXiv2022

Gravitational Wave Pathway to Testable Leptogenesis

We analyze the classically scale-invariant $B-L$ model in the context of resonant leptogenesis with the recently proposed mass-gain mechanism. The $B-L$ symmetry breaking in this scenario is associated with a strong first order phase transition that gives rise to detectable gravitational waves (GWs) via bubble collisions. The same $B-L$ symmetry breaking also gives Majorana mass to right-handed neutrinos inside the bubbles, and their out of equilibrium decays can produce the observed baryon asymmetry of the Universe via leptogenesis. We show that the current LIGO-VIRGO limit on stochastic GW background already excludes part of the $B-L$ parameter space, complementary to the collider searches for heavy $Z^{\prime}$ resonances. Moreover, future GW experiments like Einstein Telescope and Cosmic Explorer can effectively probe the parameter space of leptogenesis over a wide range of the $B-L$ symmetry-breaking scales and gauge coupling values.

hep-ph↗

arXiv2022

Hints of Natural Supersymmetry in Flavor Anomalies?

The recent results from the Fermilab muon $g-2$ experiment, as well as the persisting hints of lepton flavor universality violation in $B$-meson decays, present a very strong case for flavor-nonuniversal new physics beyond the Standard Model. We assert that a minimal $R$-parity violating supersymmetric scenario with relatively light third-generation sfermions (dubbed as 'RPV3') provides a natural, well-motivated framework for the simultaneous explanation of all flavor anomalies, while being consistent with a multitude of low-energy flavor constraints, as well as with limits from high-energy collider searches. We further propose complementary tests and distinct signatures of this scenario in the high-$p_T$ searches at current and future colliders. Specifically, we find that an sbottom in the mass range of 2-12 TeV accounts for $R_{D^{(*)}}$ and $R_{K^{(*)}}$ flavor anomalies and it only plays a minor role in the $(g-2)_μ$ anomaly, whereas a sneutrino with mass between 0.7-1 TeV is the dominant player for $(g-2)_μ$. In this context, we propose specific collider signatures of sbottom via its decays to $ \overline{ t}(t) μ^+ μ^-$, and of sneutrino pairs with their decays leading to a highly distinctive and spectacular four-muon final state, which can be used to completely probe the RPV3 parameter space of interest.

hep-ph↗

arXiv2022

Improved stellar limits on a light CP-even scalar

We derive improved stellar luminosity limits on a generic light CP-even scalar field $S$ mixing with the Standard Model (SM) Higgs boson from the supernova SN1987A, the Sun, red giants (RGs) and white dwarfs (WDs). For the first time, we include the geometric effects for the decay and absorption of $S$ particles in the stellar interior. For SN1987A and the Sun, we also take into account the detailed stellar profiles. We find that a broad range of the scalar mass and mixing angle can be excluded by our updated astrophysical constraints. For instance, SN1987A excludes $1.0\times10^{-7} \lesssim \sinθ\lesssim 3.0\times 10^{-5}$ and scalar mass up to 219 MeV, which covers the cosmological blind spot with a high reheating temperature. The updated solar limit excludes the mixing angle in the range of $1.5\times 10^{-12} < \sinθ< 1$, with scalar mass up to 45 keV. The RG and WD limits are updated to $5.3\times 10^{-13} < \sin θ< 0.39$ and $2.8\times 10^{-18} < \sin θ< 1.8\times 10^{-4}$, with scalar mass up to 392 keV and 290 keV, respectively.

hep-ph↗

arXiv2022

Probing the minimal $U(1)_X$ model at future electron-positron colliders via the fermion pair-production channel

The minimal $U(1)_X$ extension of the Standard Model (SM) is a well-motivated new physics scenario, where anomaly cancellation dictates new neutral gauge boson ($Z^\prime$) couplings with the SM fermions in terms of the $U(1)_X$ charges of the new scalar fields. We investigate the SM charged fermion pair-production process for different values of these $U(1)_X$ charges at future $e^-e^+$ colliders: $e^+e^-\to f\bar f$. Apart from the standard $γ$ and $Z$-mediated processes, this model features additional $s$-channel (or both $s$ and $t$-channel when $f=e^-$) $Z^\prime$ exchange which interferes with the SM processes. We first estimate the bounds on the $U(1)_X$ coupling $(g^\prime)$ and the $Z^\prime$ mass $(M_{Z^\prime})$ considering the latest dilepton and dijet constraints from the heavy resonance searches at the LHC. Then using the allowed values of $g^\prime$, we study the angular distributions, forward-backward $(\mathcal{A}_{\rm{FB}})$, left-right $(\mathcal{A}_{\rm{LR}})$ and left-right forward-backward $(\mathcal{A}_{\rm{LR, FB}})$ asymmetries of the $f\bar{f}$ final states. We find that these observables can show substantial deviations from the SM results in the $U(1)_X$ model, thus providing a powerful probe of the multi-TeV $Z^\prime$ bosons at future $e^+e^-$ colliders.

hep-ph↗

arXiv2022

Probes of Heavy Sterile Neutrinos

We review probes of heavy sterile neutrinos, focusing on direct experimental searches and neutrinoless double beta decay. Working in a phenomenological parametrization, we emphasize the importance of the nature of sterile neutrinos in interpreting neutrinoless double beta decay searches. While current constraints on the active-sterile neutrino mixing are already stringent, we highlight planned future efforts that will probe regimes motivated by the lightness of active neutrinos.

hep-ph↗

arXiv2022

Searching for new physics from SMEFT and leptoquarks at the P2 experiment

The P2 experiment aims at high-precision measurements of the parity-violating asymmetry in elastic electron-proton and electron-$^{12}$C scatterings with longitudinally polarized electrons. We discuss here the sensitivity of P2 to leptoquarks, which within the P2 energy range can be described in the language of Standard Model Effective Field Theory (SMEFT). We give the expected P2 limits on the SMEFT operators and on the leptoquark parameters, which will test energy scales up to 15 TeV. In many cases those limits exceed current constraints from LHC and atomic parity violation (APV) experiments. We also demonstrate that degeneracies of different SMEFT operators can partially be resolved by use of APV experiments and different targets (protons and $^{12}$C) at P2. Moreover, we show that P2 could confirm or resolve potential tensions between the theoretical and experimental determinations of the weak charge of $^{133}$Cs.

hep-ph↗

arXiv2022

Leptonic Scalars and Collider Signatures in a UV-complete Model

We study the non-standard interactions of neutrinos with light leptonic scalars ($ϕ$) in a global $(B-L)$-conserved ultraviolet (UV)-complete model. The model utilizes Type-II seesaw motivated neutrino interactions with an $SU(2)_L$-triplet scalar, along with an additional singlet in the scalar sector. This UV-completion leads to an enriched spectrum and consequently new observable signatures. We examine the low-energy lepton flavor violation constraints, as well as the perturbativity and unitarity constraints on the model parameters. Then we lay out a search strategy for the unique signature of the model resulting from the leptonic scalars at the hadron colliders via the processes $H^{\pm\pm} \to W^\pm W^\pm ϕ$ and $H^\pm \to W^\pm ϕ$ for both small and large leptonic Yukawa coupling cases. We find that via these associated production processes at the HL-LHC, the prospects of doubly-charged scalar $H^{\pm\pm}$ can reach up to 800 (500) GeV and 1.1 (0.8) TeV at the $2σ\ (5σ)$ significance for small and large Yukawa couplings, respectively. A future 100 TeV hadron collider will further increase the mass reaches up to 3.8 (2.6) TeV and 4 (2.7) TeV, at the $2σ\ (5σ)$ significance, respectively. We also demonstrate that the mass of $ϕ$ can be determined at about 10% accuracy at the LHC for the large Yukawa coupling case even though it escapes as missing energy from the detectors.

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