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2019:groups:higgs:lightscalars [2019/06/27 16:39] aoife.bharucha |
2019:groups:higgs:lightscalars [2019/06/28 11:15] (current) suzanne.gascon |
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Below 80-90GeV, for a generic (pseudo-)scalar $\phi$ (light Higgs, radion, dilaton, axion, ALP's...), the decay $\phi$ → Z*Z is kinematically closed and $\phi$ → $\gamma\gamma$ becomes challenging to trigger on, so that the gluon-gluon Fusion mechanism to produce $\phi$ is not promising anymore (see for instance [[https://arxiv.org/abs/1607.08653|1607.08653]]). | Below 80-90GeV, for a generic (pseudo-)scalar $\phi$ (light Higgs, radion, dilaton, axion, ALP's...), the decay $\phi$ → Z*Z is kinematically closed and $\phi$ → $\gamma\gamma$ becomes challenging to trigger on, so that the gluon-gluon Fusion mechanism to produce $\phi$ is not promising anymore (see for instance [[https://arxiv.org/abs/1607.08653|1607.08653]]). | ||
- | * Quick contur study using the BNT ALP UFO file. All couplings set to zero except the photons which is scanned over. {{ :2019:groups:higgs:combinedhybrid.pdf | 2D scan }}. Over a wide range of $\phi$ masses ($M_{ALP}$ on the plot) the sensitivity extends down to $C_{\gamma\gamma}/\Lambda \approx 3$ TeV$^{-1}$. Here the scan is performed over the following ranges: $m_a:\quad 1 \to 50$ GeV, $g_{a\gamma\gamma}:\quad 10 \to 10^-6$, $g_{aZ\gamma}:\quad 10 \to 10^-6$ | + | * Quick contur study using the BNT ALP UFO file. All couplings set to zero except the photons which is scanned over. {{ :2019:groups:higgs:combinedhybrid.pdf | 2D scan }}. Over a wide range of $\phi$ masses ($M_{ALP}$ on the plot) the sensitivity extends down to $C_{\gamma\gamma}/\Lambda \approx 3$ TeV$^{-1}$. Here the scan is performed over the following ranges: $m_a:$ 1 to 50 GeV, $g_{a\gamma\gamma}$: 10 to $10^{-6}$, $g_{aZ\gamma}$: 10 to $10^{-6}$ |
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* Checking at an example point in the above scan, $M_{ALP} = 1.8$ GeV, $C_{\gamma\gamma}/\Lambda = 5.2$ TeV$^{-1}$, all other couplings set to zero. The $\phi$ decays 100% to $\gamma\gamma$ as expected (width $10^{-7}$ GeV). The main production mechanisms are $\gamma, W$ or $Z$ + $\phi$. $gg \rightarrow \phi$ is zero. The different subprocess cross sections are visible in the example Herwig output file: {{ :2019:groups:higgs:lhc-s101-runpoint_0095.out.txt | lhc-s101-runpoint_0095.out}} | * Checking at an example point in the above scan, $M_{ALP} = 1.8$ GeV, $C_{\gamma\gamma}/\Lambda = 5.2$ TeV$^{-1}$, all other couplings set to zero. The $\phi$ decays 100% to $\gamma\gamma$ as expected (width $10^{-7}$ GeV). The main production mechanisms are $\gamma, W$ or $Z$ + $\phi$. $gg \rightarrow \phi$ is zero. The different subprocess cross sections are visible in the example Herwig output file: {{ :2019:groups:higgs:lhc-s101-runpoint_0095.out.txt | lhc-s101-runpoint_0095.out}} | ||
+ | * Some more scans as suggested by Aoife and Jose: | ||
+ | * {{:2019:groups:higgs:combinedhybrid50.png?200|}} | ||
+ | * {{:2019:groups:higgs:combinedhybrid30.png?200|}} | ||
+ | * {{:2019:groups:higgs:combinedhybrid10.png?200|}} | ||
For instance, Higgs composite models with additional light scalars:[[https://arxiv.org/pdf/1810.11142.pdf|1710.11142]], [[https://arxiv.org/pdf/1902.08690.pdf|1902.08690]]. | For instance, Higgs composite models with additional light scalars:[[https://arxiv.org/pdf/1810.11142.pdf|1710.11142]], [[https://arxiv.org/pdf/1902.08690.pdf|1902.08690]]. | ||
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* ... | * ... | ||
- | Promising DECAYS: $\phi\to\gamma\gamma$ (and $\mu\mu$, $bb$, $\tau\tau$, Missing E_T ?) [names: **TF**] | + | Promising DECAYS: $\phi\to\gamma\gamma$ (and $\mu\mu$, $bb$, $\tau\tau$, Missing E_T ?) [names: **TF, JZ**] |
General comment: If the particle is lighter than hadronic threshold ($m_a <3m_\pi<450\rm MeV$ for CP-odd scalar), the particle is easily long-lived in the reasonable parameter space. Many literature ignores loop-factor $16\pi^2$, which sometimes leads to less physical parameter space. A scale $\Lambda/C_{\gamma\gamma}=1\rm TeV$ in [[https://arxiv.org/abs/1708.00443|1708.00443]] parameterization corresponds to a scale $f_a =6\rm GeV$ in the decay constant (SSB scale).So ALP being invisible is quite possible with sub-GeV mass and $f_a >100\rm GeV$. Estimates with ALP as missing energy in [[https://arxiv.org/abs/1409.4792|1409.4792]] (mono-jet), [[https://arxiv.org/abs/1701.05379|1701.05379]] (mono-W, mono-Z, mono-Higgs) and [[https://arxiv.org/abs/1901.03061|1901.03061]]. | General comment: If the particle is lighter than hadronic threshold ($m_a <3m_\pi<450\rm MeV$ for CP-odd scalar), the particle is easily long-lived in the reasonable parameter space. Many literature ignores loop-factor $16\pi^2$, which sometimes leads to less physical parameter space. A scale $\Lambda/C_{\gamma\gamma}=1\rm TeV$ in [[https://arxiv.org/abs/1708.00443|1708.00443]] parameterization corresponds to a scale $f_a =6\rm GeV$ in the decay constant (SSB scale).So ALP being invisible is quite possible with sub-GeV mass and $f_a >100\rm GeV$. Estimates with ALP as missing energy in [[https://arxiv.org/abs/1409.4792|1409.4792]] (mono-jet), [[https://arxiv.org/abs/1701.05379|1701.05379]] (mono-W, mono-Z, mono-Higgs) and [[https://arxiv.org/abs/1901.03061|1901.03061]]. | ||
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Please send to Gregory, Susan and Jose by Thursday morning (so we can give a synthesis to the speaker by ~Thursday noon and also circulate among us) | Please send to Gregory, Susan and Jose by Thursday morning (so we can give a synthesis to the speaker by ~Thursday noon and also circulate among us) | ||
+ | Thank you all for all the work, and let's not stop here! {{ :2019:groups:higgs:suzannegregorylightscalarlhc2019slides.ppt | Here }} are the slides shown in the summary session on June 28, 2019. |