We investigate the non-zero temperature dynamics of a sub-GeV dark matter scenario freezing-out via self-interactions. As a prototype, we take up the case of a scalar dark matter species undergoing <math altimg='si1.svg'><mn>3</mn><mo stretchy='false'>&#8594;</mo><mn>2</mn></math> number changing annihilations catalysed by another scalar. We study the shape of the thermal potential of this scenario in a parameter region accounting for the observed relic abundance. An analysis reveals the possibility of a first order phase transition with bubble nucleation occurring at sub-GeV temperatures. This finding can be correlated with the typical sub-GeV masses in the framework. The gravitational wave spectra associated with such a phase transition is subsequently computed.

India

Nabarun Chakrabarty

Himadri Roy

Tripurari Srivastava

Single-step first order phase transition and gravitational waves in a SIMP dark matter scenario

The recent precise measurement of the <math><mi>W</mi></math>-mass by the CDF II Collaboration could be indicative of new physics beyond the Standard Model. On the other hand, a resolution of the long-standing muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> anomaly also calls for additional dynamics. In this work, we accommodate the two aforementioned anomalies in an extension of the minimal type-II seesaw model. That is, the minimal type-II model is augmented with an additional doubly charged scalar and vectorlike leptons. While a chirality flip of the vectorlike leptons can predict the observed value of muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math>, the value of the recently reported <math><mi>W</mi></math> mass can also be simultaneously achieved through the oblique parameters of the model. In addition, we further show that the parameter region allowing for the simultaneous resolution of the two anomalies complies with the neutrino mass data, lepton flavor violation, and electroweak vacuum stability up to the Planck scale.

Muon <math><mrow><mi>g</mi><mo>−</mo><mn>2</mn></mrow></math> and <math><mrow><mi>W</mi></mrow></math>-mass anomalies explained and the electroweak vacuum stabilized by extending the minimal type-II seesaw model

A color octet isodoublet can have esoteric origins and it complies with minimal flavour violation. In this study, we take a scenario where the well known Type-X Two-Higgs doublet model is augmented with a color octet isodoublet. We shed light on how such a setup can predict the recently observed value for the W-boson mass. The two-loop Barr-Zee contributions to muon  $$g-2$$  <math> <mrow> <mi>g</mi> <mo>-</mo> <mn>2</mn> </mrow> </math>   stemming from the colored scalars are evaluated. It is subsequently found that the parameter space compatible with the observed muon  $$g-2$$  <math> <mrow> <mi>g</mi> <mo>-</mo> <mn>2</mn> </mrow> </math>   gets relaxed w.r.t. what it is in the pure Type-X 2HDM by virtue of the contribution from the colored scalars. The extended parameter region therefore successfully accounts for both the W-mass and muon  $$g-2$$  <math> <mrow> <mi>g</mi> <mo>-</mo> <mn>2</mn> </mrow> </math>   anomalies simultaneously. Finally, a collider signature leading to a  $$\tau ^+ \tau ^- b \overline{b}$$  <math> <mrow> <msup> <mi>τ</mi> <mo>+</mo> </msup> <msup> <mi>τ</mi> <mo>-</mo> </msup> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> </mrow> </math>   final state is explored at the 14 TeV LHC using both cut-based and multivariate techniques. Such a signal can confirm the existence of both colorless as well colored scalars that are introduced by this framework.

Indrani Chakraborty

Dilip Ghosh

Gourab Saha

Muon  $$g-2$$  <math> <mrow> <mi>g</mi> <mo>-</mo> <mn>2</mn> </mrow> </math>   and W-mass in a framework of colored scalars: an LHC perspective

A two-Higgs doublet model can predict the observed muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> for an appropriately light pseudoscalar that now faces tight constraints. However, it was shown recently in the companion paper [N. Chakrabarty, Muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> in a type-X 2HDM assisted by inert scalars: A test at the LHC, preceding paper, arXiv:2112.13126.] that augmenting the two-Higgs doublet model by an additional inert doublet can lead to an explanation to the muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> anomaly for a much heavier pseudoscalar. In this study, we probe such a framework at the proposed International Linear Collider using beam polarization for <math><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>. Using multivariate techniques, we analyze the signals <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo>→</mo><msup><mi>τ</mi><mo>+</mo></msup><msup><mi>τ</mi><mo>−</mo></msup><mo>+</mo></math> missing transverse energy and <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup><mo>→</mo><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>−</mo></msup><mo>+</mo></math> missing transverse energy in the lepton- and muon-specific versions of the framework, respectively. Our analysis reveals that the <math><msup><mi>e</mi><mo>+</mo></msup><msup><mi>e</mi><mo>−</mo></msup></math> machine operating at a <math><mn>3000</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> luminosity predicts a <math><mrow><mn>5</mn><mi>σ</mi></mrow></math> discovery of a pseudoscalar as heavy as 400 GeV. Comparing with the companion paper, it is concluded that the International Linear Collider is a much more potent machine than the LHC in this regard.

Muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> in a type-X 2HDM assisted by inert scalars: A test at the ILC

A scenario augmenting the well-known type-X two-Higgs doublet model with an additional inert doublet is proposed. The type-X two-Higgs doublet model is known to offer a solution to the muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> anomaly for a light pseudoscalar. We show that the proposed framework can accommodate a heavier pseudoscalar on account of two-loop Barr-Zee contributions to muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> stemming from the inert doublet. We subsequently explore an interesting <math><msup><mi>τ</mi><mo>+</mo></msup><msup><mi>τ</mi><mo>−</mo></msup><mo>+</mo></math> missing transverse energy signal that can be used to probe the present scenario at the 14 TeV LHC.

Muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> in a type-X 2HDM assisted by inert scalars: A test at the LHC

If coupled feebly to the Standard Model bath, dark matter can evade the severe constraints from the direct search experiments. At the same time, such interactions help produce dark matter via the freeze-in mechanism. The freeze-in scenario becomes more interesting if one also includes the thermal masses of the different particles involved in the dark matter phenomenology. Incorporating such thermal corrections opens up the possibility of dark matter production via channels that remain kinematically disallowed in the standard freeze-in setup. Motivated by this, we investigate such freeze-in production of the dark matter in a minimally extended <math><mi>U</mi><mo>(</mo><mn>1</mn><msub><mo>)</mo><mrow><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></mrow></msub></math> framework, which is also known to resolve the muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> anomaly. Here, the role of the dark matter is played by a scalar with a nontrivial charge under the additional symmetry <math><mi>U</mi><mo>(</mo><mn>1</mn><msub><mo>)</mo><mrow><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></mrow></msub></math>. The importance of incorporating the appropriate finite temperature corrections to freeze-in dynamics is aptly demonstrated in this study using the <math><mi>U</mi><mo>(</mo><mn>1</mn><msub><mo>)</mo><mrow><msub><mi>L</mi><mi>μ</mi></msub><mo>−</mo><msub><mi>L</mi><mi>τ</mi></msub></mrow></msub></math> scenario as a prototype.

Partha Konar

South Korea

Rishav Roshan

Sudipta Show

Thermally corrected masses and freeze-in dark matter: A case study

A three Higgs-doublet model exhibiting   $S_3$  -symmetry can predict the observed pattern of quark masses and their mixings. However, the same symmetry also introduces potential flavor-changing neutral currents (FCNCs) at the tree level. In this study, we assume that the scalar potential contains appropriate soft   $S_3$  -breaking terms to maintain flexible choices of scalar masses. We identify the parameters in the Yukawa Lagrangian of the quark sector responsible for such FCNCs and constrain them using data from flavor physics observables, such as meson-decays and meson-mixings. We also validate the corresponding model parameter space via renormalization group evaluation.

Flavor-alignment in an  -symmetric Higgs sector and its RG-behavior  

A two-component scalar dark matter scenario comprising an additional scalar doublet and a <math><mi>Y</mi><mo>=</mo><mn>0</mn></math> scalar triplet is proposed. Key features of the ensuing dark matter phenomenology are highlighted with emphasis on interconversion between the two dark matter components. For suitable choices of the model parameters, we show that such interconversion can explain the observed relic abundance when the doublet dark matter component has mass in the desert region while the triplet component has sub-TeV mass. This finding is important in the context of such mass regions known to predict underabundant relic density for the stand-alone cases of the scalar doublet and triplet. In addition, we also show that the present scenario can stabilize the electroweak vacuum up to the Planck scale in the parameter space responsible for the requisite dark matter observables.

Arunansu Sil

Two-component doublet-triplet scalar dark matter stabilizing the electroweak vacuum

We examine the relic density of the light mass dark matter region in the inert doublet model (IDM) when the dominant process is due to coannihilation between the lightest neutral scalars of the model. The full one-loop electroweak corrections are computed in an on shell scheme and are found to be well approximated as an effective cross section expressed in terms of <math><mi>Z</mi></math> observables. The electroweak corrections to the subdominant process, which consists of an annihilation into an on shell <math><mi>W</mi></math> and an off shell <math><mi>W</mi></math>, that is calculated as a annihilation into a three-body final state, is also performed. In the calculation of the latter in this case of coannihilation, although the SM Higgs exchange is absent, it is induced at one loop, but the cross section does not show a peak behavior despite the crossing of the Higgs resonance. This cross section reveals an important dependence on a parameter that describes the self-interaction of the new scalars (solely within the dark sector), a parameter which is not accessible in tree-level calculations of standard model-IDM interactions.

CERN

Shankha Banerjee

France

Fawzi Boudjema

China

Hao Sun

Relic density of dark matter in the inert doublet model beyond leading order for the low mass region. II. Coannihilation

The present paper is the first in a series that addresses the calculation of the full one-loop corrections of dark matter (DM) annihilation cross sections in the low mass region of the inert doublet model (IDM). This series is a sequel to our recent publication concerning these corrections in the high mass region. We first review the renormalization of the model both in a fully on shell (OS) scheme as well as in a mixed scheme that combines on shell (for the masses) and a <math><mover><mi>MS</mi><mo>¯</mo></mover></math> approach when the partial invisible width is closed and does not allow the use of a full OS scheme. The scale dependence introduced by the mixed scheme is shown to be tracked through an analysis of a parametrization of the tree-level cross section and the <math><mi>β</mi></math> constant of a specific coupling; this analysis could be followed in theories. We discuss how to minimize the scale dependence. The theoretical uncertainty brought by the scale dependence leads us to introduce a new criterion on the perturbativity of the IDM. This criterion further delimits the allowed parameter space, which we investigate carefully by including a host of constraints, both theoretical and experimental, including in particular, new data from the LHC. We come up with a set of benchmark points that cover three different mechanisms for a viable relic density of DM: (i) a dominance of coannihilation into a fermion pair, (ii) annihilation into two vector bosons of which one is off shell that requires the calculation of a <math><mn>2</mn><mo>→</mo><mn>3</mn></math> process, (iii) annihilation that proceeds through the very narrow standard model Higgs resonance. Since the <math><mn>2</mn><mo>→</mo><mn>3</mn></math> vector boson channel features in all three channels and is essentially a buildup on the simpler annihilation to OS vector bosons, we study the latter in detail in the present paper. We confirm again that the corrected cross sections involve a parameter that can be considered as rescattering in the dark sector, which a tree-level computation is not sensitive to. The setup of the renormalization detailed in the present paper will be the backbone of the accompanying papers where each mechanism requires, calculationally, a specific treatment. One-loop corrections to <math><mn>2</mn><mo>→</mo><mn>3</mn></math> processes for DM annihilation are technically challenging and have not been attempted before. We dedicate one of the accompanying papers to such a computation. The one-loop correction in the presence of a resonance will be presented separately since we need to supplement our general schemes with a complex scheme. For the coannihilation into fermions, our study will show that the annihilation cross sections can be excellently parametrized through simple effective couplings.