The SU(2)–gauged custodial two-Higgs-doublet model, which shares the same global-symmetry properties with the standard model, is studied non-perturbatively on the lattice. The additional Higgs doublet enlarges the scalar spectrum and opens the possibility for spontaneous breaking of the global symmetry. In this work we start by showing the occurrence of spontaneous breaking of the custodial symmetry in a region of the parameter space of the model. Following this, both the spectrum and the running of the gauge coupling of are examined at weak quartic couplings in the presence of the custodial symmetry. The calculations are performed with energy cutoffs ranging from 300 to 600 GeV on a line of constant standard model physics, obtained by tuning bare couplings to fix the ratio between the masses of the Higgs and the $\textit{W}$ bosons, as well as the value of the renormalized gauge coupling at the scale of the $\textit{W}$ boson mass. The realizable masses for the additional scalar states are explored. For the choice of bare quartic couplings in this work, the estimated lower bound of these masses is found to be well below the $\textit{W}$ boson mass, and independent of the cutoff. We also study the finite temperature electroweak transition along this line of constant standard model physics, revealing properties of a smooth crossover behavior.

Italy

Spain

Guilherme Catumba

Japan

Taiwan

Atsuki Hiraguchi

Wei-Shu Hou

Germany

Karl Jansen

Ying-Jer Kao

C.J. Lin

Alberto Ramos

Mugdha Sarkar

Lattice investigation of custodial two-Higgs-doublet model at weak quartic couplings

We investigate the LHC discovery prospects for a second Higgs doublet through <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi></math> weak decay. The latter is identified as the smoking gun signature of two Higgs doublet models (2HDMs) with first-order electroweak (EW) phase transition, a necessary condition for EW baryogenesis. In the general 2HDM (G2HDM) that has flavor-changing neutral Higgs couplings, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>H</mi></math> may decay dominantly via <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover><mo>+</mo><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></math> final states, giving rise to trilepton signals. By a phenomenological analysis, we show that <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi></math> in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup><mi>t</mi><mover accent="true"><mi>c</mi><mo stretchy="false">¯</mo></mover></math> or <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mo>ℓ</mo><mo>+</mo></msup><msup><mo>ℓ</mo><mo>−</mo></msup><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mi>c</mi></math> final states could be a promising probe of G2HDM at the LHC with flavor violation.

Mohamed Krab

Probing the general 2HDM with flavor violation through <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>A</mi><mo stretchy="false">→</mo><mi>Z</mi><mi>H</mi></math>

We suggest a resonant <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>c</mi><mover accent="true"><mi>b</mi><mo stretchy="false">¯</mo></mover><mo stretchy="false">→</mo><msup><mi>H</mi><mo>+</mo></msup></math> production search, followed by bosonic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>H</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>W</mi><mo>+</mo></msup><mi>H</mi></math> weak decay at the Large Hadron Collider (LHC). In the general two-Higgs-doublet model (G2HDM) that has flavor-changing neutral Higgs couplings, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>H</mi><mo>+</mo></msup></math> is resonantly produced via the top-charm <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ρ</mi><mrow><mi>t</mi><mi>c</mi></mrow></msub><msub><mi>V</mi><mrow><mi>t</mi><mi>b</mi></mrow></msub></math> coupling at tree level, while <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>H</mi><mo>+</mo></msup><mo stretchy="false">→</mo><msup><mi>W</mi><mo>+</mo></msup><mi>H</mi></math> weak decay occurs within the exotic second doublet, leading eventually to same-sign dilepton signals. We perform a signal-to-background analysis at the 14 TeV LHC and show that discovery seems possible with LHC Run 2 data already at hand.

Searching for resonant flavor-changing charged Higgs production at the LHC

We study the discovery prospects for a charged Higgs boson via the <math><mi>b</mi><mi>g</mi><mo>→</mo><mi>c</mi><msup><mi>H</mi><mo>−</mo></msup><mo>→</mo><mi>c</mi><mover><mi>t</mi><mo>¯</mo></mover><mi>b</mi></math> process at the Large Hadron Collider (LHC). Focusing on the general two Higgs doublet model (G2HDM) that possesses extra Yukawa couplings, the process is controlled by extra top couplings <math><msub><mi>ρ</mi><mrow><mi>t</mi><mi>c</mi></mrow></msub></math> and <math><msub><mi>ρ</mi><mrow><mi>t</mi><mi>t</mi></mrow></msub></math>, which can drive electroweak baryogenesis (EWBG) to account for the baryon asymmetry of the Universe (BAU). We propose benchmark points (BPs) and demonstrate that evidence could emerge at 14 TeV LHC and luminosity of <math><mrow><mn>300</mn><mtext> </mtext><mtext> </mtext><msup><mrow><mi>fb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math>, with discovery potential at <math><mn>600</mn><mtext> </mtext><mtext> </mtext><msup><mi>fb</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math>.

Reconstructing the general 2HDM charged Higgs boson at the LHC

Baryon asymmetry of the Universe offers one of the strongest hints for physics beyond the Standard Model (BSM). Remarkably, in the general two Higgs doublet model (<math><mrow><mrow><mi>g</mi></mrow><mn>2</mn><mi>HDM</mi></mrow></math>) that possesses a second set of Yukawa matrices, one can have electroweak baryogenesis (EWBG) while the electron electric dipole moment (eEDM) is evaded by a natural flavor tuning that echoes the Standard Model (SM). We show that eEDM may first emerge around <math><msup><mn>10</mn><mrow><mo>−</mo><mn>30</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>e</mi><mtext> </mtext><mi>cm</mi></math> or so, followed by neutron EDM (nEDM) down to <math><msup><mn>10</mn><mrow><mo>−</mo><mn>27</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>e</mi><mtext> </mtext><mi>cm</mi></math>. We illustrate a cancellation mechanism for nEDM itself, which in turn can be probed when a facility capable of pushing down to <math><msup><mn>10</mn><mrow><mo>−</mo><mn>28</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mi>e</mi><mtext> </mtext><mi>cm</mi></math> becomes available.

Girish Kumar

Sven Teunissen

Discovery prospects for electron and neutron electric dipole moments in the general two Higgs doublet model

With the Large Hadron Collider (LHC) running, we should probe electroweak baryogenesis (EWBG) while probing <math><mrow><mi>C</mi><mi>P</mi></mrow></math> violation (<math><mi>C</mi><mi>P</mi><mi>V</mi></math>) with electron electric dipole moment (eEDM). Rooted in the flavor structure of the Standard Model (SM), the general two Higgs doublet model (g2HDM) with a second set of Yukawa couplings can deliver EWBG while surviving eEDM. We point out a chiral-enhanced top-bottom interference effect that makes <math><mi>b</mi><mo>→</mo><mi>s</mi><mi>γ</mi></math> decay an exquisite window on EWBG and eEDM, and illustrate the importance of the <math><mi>Δ</mi><msub><mi>A</mi><mrow><mi>C</mi><mi>P</mi></mrow></msub></math> observable at Belle II.

United States

Tanmoy Modak

Probing baryogenesis with radiative beauty decay and electron electric dipole moment

We extend heavy Higgs searches at the Large Hadron Collider for $$H \rightarrow \tau \mu $$ <math> <mrow> <mi>H</mi> <mo>→</mo> <mi>τ</mi> <mi>μ</mi> </mrow> </math> by CMS, and $$H \rightarrow \tau \tau $$ <math> <mrow> <mi>H</mi> <mo>→</mo> <mi>τ</mi> <mi>τ</mi> </mrow> </math> by ATLAS and CMS, to study discovery prospects of extra Higgs states in $$pp \rightarrow H,A \rightarrow \tau \mu , \tau \tau $$ <math> <mrow> <mi>p</mi> <mi>p</mi> <mo>→</mo> <mi>H</mi> <mo>,</mo> <mi>A</mi> <mo>→</mo> <mi>τ</mi> <mi>μ</mi> <mo>,</mo> <mi>τ</mi> <mi>τ</mi> </mrow> </math> with and final states, where $$j_{\tau } = \pi \,, \rho \,, a_1$$ <math> <mrow> <msub> <mi>j</mi> <mi>τ</mi> </msub> <mo>=</mo> <mi>π</mi> <mspace width="0.166667em"></mspace> <mo>,</mo> <mi>ρ</mi> <mspace width="0.166667em"></mspace> <mo>,</mo> <msub> <mi>a</mi> <mn>1</mn> </msub> </mrow> </math> and is missing transverse energy. In a general two Higgs doublet model without $$Z_2$$ <math> <msub> <mi>Z</mi> <mn>2</mn> </msub> </math> symmetry, extra Yukawa couplings $$\rho _{\tau \tau }$$ <math> <msub> <mi>ρ</mi> <mrow> <mi>τ</mi> <mi>τ</mi> </mrow> </msub> </math> and $$\rho _{\tau \mu }$$ <math> <msub> <mi>ρ</mi> <mrow> <mi>τ</mi> <mi>μ</mi> </mrow> </msub> </math> can drive $$H,A \rightarrow \tau \tau $$ <math> <mrow> <mi>H</mi> <mo>,</mo> <mi>A</mi> <mo>→</mo> <mi>τ</mi> <mi>τ</mi> </mrow> </math> and $$\tau \mu $$ <math> <mrow> <mi>τ</mi> <mi>μ</mi> </mrow> </math> channels at hadron colliders, following gluon–gluon fusion production with extra $$\rho _{tt}$$ <math> <msub> <mi>ρ</mi> <mrow> <mi>tt</mi> </mrow> </msub> </math> couplings. The light Higgs boson h(125) is found to resemble closely the Standard Model Higgs boson; in the alignment limit of $$\cos \gamma \rightarrow 0$$ <math> <mrow> <mo>cos</mo> <mi>γ</mi> <mo>→</mo> <mn>0</mn> </mrow> </math> for h–H mixing, flavor changing neutral Higgs couplings such as $$h \rightarrow \tau \mu $$ <math> <mrow> <mi>h</mi> <mo>→</mo> <mi>τ</mi> <mi>μ</mi> </mrow> </math> are naturally suppressed, but the couplings of the heavier H is optimized by $$\sin \gamma \rightarrow 1$$ <math> <mrow> <mo>sin</mo> <mi>γ</mi> <mo>→</mo> <mn>1</mn> </mrow> </math> . We define various signal regions for $$H,A \rightarrow \tau \mu $$ <math> <mrow> <mi>H</mi> <mo>,</mo> <mi>A</mi> <mo>→</mo> <mi>τ</mi> <mi>μ</mi> </mrow> </math> and $$\tau \tau $$ <math> <mrow> <mi>τ</mi> <mi>τ</mi> </mrow> </math> and evaluate physics backgrounds from dominant processes with realistic acceptance cuts and tagging efficiencies. Two different studies are presented. We first perform a parton level study without any hadronization and with minimal detector smearing. We then include hadronization using PYTHIA 8.2 and fast detector simulation using DELPHES to give event level simulation. Results for $$\sqrt{s}= 13$$ <math> <mrow> <msqrt> <mi>s</mi> </msqrt> <mo>=</mo> <mn>13</mn> </mrow> </math> TeV appear promising, which we extend further to $$\sqrt{s} = 14$$ <math> <mrow> <msqrt> <mi>s</mi> </msqrt> <mo>=</mo> <mn>14</mn> </mrow> </math> TeV for the High Luminosity LHC.

Rishabh Jain

Chung Kao

Prospects for extra Higgs boson search via $$pp\rightarrow H,A\rightarrow \tau \mu , \tau \tau $$ <math> <mrow> <mi>p</mi> <mi>p</mi> <mo>→</mo> <mi>H</mi> <mo>,</mo> <mi>A</mi> <mo>→</mo> <mi>τ</mi> <mi>μ</mi> <mo>,</mo> <mi>τ</mi> <mi>τ</mi> </mrow> </math> at the high luminosity Large Hadron Collider

We study lepton flavor violating (LFV) <math><mi>B</mi></math> decays in a general two Higgs doublet model with sub-TeV exotic scalars. Two different parameter spaces are explored: one dominated by extra top Yukawa coupling <math><msub><mi>ρ</mi><mrow><mi>t</mi><mi>t</mi></mrow></msub></math>, the other by LFV couplings relevant for the muon <math><mi>g</mi><mo>−</mo><mn>2</mn></math> anomaly. In the first case, flavor constraints such as <math><mo>ℓ</mo><mo>→</mo><msup><mo>ℓ</mo><mo>′</mo></msup><mi>γ</mi></math>, <math><mi>h</mi><mo>→</mo><mo>ℓ</mo><msup><mo>ℓ</mo><mo>′</mo></msup></math> imply LFV <math><mi>B</mi></math> decays are far below experimental sensitivities. The second case needs to be close to the alignment limit, but <math><msub><mi>B</mi><mi>q</mi></msub><mo>→</mo><mi>τ</mi><mi>μ</mi></math> and <math><mi>B</mi><mo>→</mo><mo>(</mo><mi>K</mi><mo>,</mo><mi>π</mi><mo>)</mo><mi>τ</mi><mi>μ</mi></math> rates can lie within the sensitivities of Belle II and LHCb Upgrade II. Neutral <math><mi>B</mi></math> meson mixings and <math><mi>B</mi><mo>,</mo><mi>K</mi><mo>,</mo><mi>π</mi><mo>→</mo><mo>ℓ</mo><mi>ν</mi></math> decays provide important flavor constraints on parameter space. <math><mrow><mi>B</mi></mrow></math> decays involving <math><mi>e</mi><mi>–</mi><mi>τ</mi></math> violation are constrained by <math><mi>μ</mi><mo>→</mo><mi>e</mi></math> processes.

Enhanced <math><msub><mi>B</mi><mi>q</mi></msub><mo>→</mo><mo>ℓ</mo><msup><mo>ℓ</mo><mo>′</mo></msup></math> and <math><mrow><mi>B</mi><mo>→</mo><mo>(</mo><mi>K</mi><mo>,</mo><mi>π</mi><mo>)</mo><mo>ℓ</mo><msup><mrow><mo>ℓ</mo></mrow><mrow><mo>′</mo></mrow></msup></mrow></math> in light of <math><mo>(</mo><mi>g</mi><mo>−</mo><mn>2</mn><msub><mo>)</mo><mi>μ</mi></msub></math>

In the general two Higgs doublet model (g2HDM) that has extra Yukawa couplings, we analyze their New Physics (NP) contributions to kaon mixing parameter ε K , direct CP violation parameter ε′/ε, and rare <math> <msup> <mi>K</mi> <mo>+</mo> </msup> <mo>→</mo> <msup> <mi>π</mi> <mo>+</mo> </msup> <mi>ν</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math> $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ , <math> <msub> <mi>K</mi> <mi>L</mi> </msub> <mo>→</mo> <msup> <mi>π</mi> <mn>0</mn> </msup> <mi>ν</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math> $$ {K}_L\to {\pi}^0\nu \overline{\nu} $$ , and K L,S → μ + μ − decays. We study correlations between these observables, and call special attention to a unique complementarity of kaon mixing and rare <math> <mi>K</mi> <mo>→</mo> <mi>πν</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math> $$ K\to \pi \nu \overline{\nu} $$ decays in probing the exotic Higgs mass spectrum of g2HDM. The importance of kaon physics in probing NP vis-à-vis B physics is stressed. One unexpected feature we uncover is the special sensitivity of <math> <msup> <mi>K</mi> <mo>+</mo> </msup> <mo>→</mo> <msup> <mi>π</mi> <mo>+</mo> </msup> <mi>ν</mi> <mover> <mi>ν</mi> <mo>¯</mo> </mover> </math> $$ {K}^{+}\to {\pi}^{+}\nu \overline{\nu} $$ to TeV scale charged Higgs boson.

Strange processes in general two Higgs doublet model

We study a search for the charged Higgs boson via e + e − → H + H − → <math> <mover> <mi>c</mi> <mo>¯</mo> </mover> <mi>b</mi> <mover> <mi>c</mi> <mo>¯</mo> </mover> <mi>b</mi> </math> $$ \overline{c}b\overline{c}b $$ at the 500 GeV ILC. In a general two Higgs doublet model without Z 2 symmetry, extra Yukawa couplings ρ tt and ρ tc can drive baryogenesis, but searches at the HL-LHC may still go empty-handed if the couplings are relatively weak. Taking <math> <msub> <mi>m</mi> <msup> <mi>H</mi> <mo>+</mo> </msup> </msub> </math> $$ {m}_{H^{+}} $$ ≃ m H ≃ m A ≃ 200 GeV, with ρ tt , ρ tc ∼ 0.1 and no h(125)-H mixing, H + → <math> <mi>c</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> </math> $$ c\overline{b} $$ decay is dominant, and the <math> <mover> <mi>c</mi> <mo>¯</mo> </mover> <mi>b</mi> <mover> <mi>c</mi> <mo>¯</mo> </mover> <mi>b</mi> </math> $$ \overline{c}b\overline{c}b $$ final state is likely overwhelmed by QCD background at the LHC. We show that the electroweak production of H + H − at the ILC is discoverable with integrated luminosity of 1 ab −1. Furthermore, we show that <math> <msub> <mi>m</mi> <msup> <mi>H</mi> <mo>+</mo> </msup> </msub> </math> $$ {m}_{H^{+}} $$ can be extracted by requiring the two pairs of b and light jets be roughly equal in mass, without assuming the mass value. Thus, ILC can probe low mass Higgs bosons in multijet final states to complement HL-LHC in the future.

Searching for Charged Higgs Bosons via e + e − → H + H − → <math> <mover> <mi>c</mi> <mo>¯</mo> </mover> <mi>b</mi> <mover> <mi>c</mi> <mo>¯</mo> </mover> <mi>b</mi> </math> $$ \overline{c}b\overline{c}b $$ at Linear Colliders