The Role of Bondholders’ Coordination in Freeze-Out Exchange Offers

Context. 1-propanol (CH3CH2CH2OH) is a three carbon-bearing representative of the primary linear alcohols that may have its origin in the cold dark cores in interstellar space. To test this, we investigated in the laboratory whether 1-propanol ice can be formed along pathways possibly relevant to the prestellar core phase. Aims. We aim to show in a two-step approach that 1-propanol can be formed through reaction steps that are expected to take place during the heavy CO freeze-out stage by adding C2H2 into the CO + H hydrogenation network via the formation of propanal (CH3CH2CHO) as an intermediate and its subsequent hydrogenation. Methods. Temperature programmed desorption-quadrupole mass spectrometry (TPD-QMS) was used to identify the newly formed propanal and 1-propanol. Reflection absorption infrared spectroscopy (RAIRS) was used as a complementary diagnostic tool. The mechanisms that can contribute to the formation of solid-state propanal and 1-propanol, as well as other organic compounds, during the heavy CO freeze-out stage are constrained by both laboratory experiments and theoretical calculations. Results. Here it is shown that recombination of HCO radicals formed upon CO hydrogenation with radicals formed via C2H2 processing – H2CCH and H3CCH2 – offers possible reaction pathways to solid-state propanal and 1-propanol formation. This extends the already important role of the CO hydrogenation chain to the formation of larger complex organic molecules. The results are compared with ALMA observations. The resulting 1-propanol:propanal ratio concludes an upper limit of <0.35−0.55, which is complemented by computationally derived activation barriers in addition to the experimental results.

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Strangeness freeze-out: role of system size and missing resonances

EPJ Web of Conferences ◽

10.1051/epjconf/201817114002 ◽

2018 ◽

Vol 171 ◽

pp. 14002

Author(s):

Sandeep Chatterjee ◽

Sabita Das ◽

Ajay Kumar Dash ◽

Debadeepti Mishra ◽

Bedangadas Mohanty ◽

...

Keyword(s):

Size Dependence ◽

System Size ◽

Conventional Approach ◽

Strangeness Production ◽

Additional Parameter ◽

Theoretical Approaches ◽

Missing Resonances ◽

Freeze Out

The conventional approach to treat strangeness freezeout has been to consider a unified freezeout scheme where strangeness freezes out along with the nonstrange hadrons (1CFO), with or without an additional parameter accounting for out-of-equilibrium strangeness production (γS). Several alternate scenarios have been formulated lately. Here, we will focus on flavor dependent freezeout with early freezeout of strangeness (2CFO) in comparison to 1CFO and its variants with respect to the roles played by the system size and missing resonances predicted by different theoretical approaches but yet to be seen in experiments. In contrast to the performance of 1CFO with/without γS that is insensitive to system size, 2CFO exhibits a clear system size dependence-while for Pb+Pb the χ2/NDF is around 0-2, for smaller system size in p+Pb and p+p, the χ2/NDF> 5 and larger than 1CFO+γS. This clearly shows a system size dependence of the preference for the freezeout scheme, while 2CFO is preferred in Pb+Pb, 1CFO+γS is preferred in p+Pb and p+p. We have further investigated the role of the missing resonances on strangeness freezeout across SPS to LHC beam energies.

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Role of system size in freeze-out conditions extracted from transverse momentum spectra of hadrons

Physical Review C ◽

10.1103/physrevc.98.064902 ◽

2018 ◽

Vol 98 (6) ◽

Cited By ~ 3

Author(s):

Ajay Kumar Dash ◽

Ranbir Singh ◽

Sandeep Chatterjee ◽

Chitrasen Jena ◽

Bedangadas Mohanty

Keyword(s):

Transverse Momentum ◽

System Size ◽

Momentum Spectra ◽

Transverse Momentum Spectra ◽

Freeze Out

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A warped scalar portal to fermionic dark matter

The European Physical Journal C ◽

10.1140/epjc/s10052-021-08851-0 ◽

2021 ◽

Vol 81 (1) ◽

Author(s):

Adrian Carmona ◽

Javier Castellano Ruiz ◽

Matthias Neubert

Keyword(s):

Dark Matter ◽

Extra Dimension ◽

Early Period ◽

Scalar Particle ◽

Hierarchy Problem ◽

Warped Extra Dimension ◽

Relic Abundance ◽

Kaluza Klein ◽

Freeze Out

AbstractWe argue that extensions of the SM with a warped extra dimension, together with a new $${\mathbb {Z}}_2$$ Z 2 -odd scalar singlet, provide a natural explanation not only for the hierarchy problem but also for the nature of fermion bulk masses and the observed dark matter relic abundance. In particular, the Kaluza-Klein excitations of the new scalar particle, which is required to naturally obtain fermion bulk masses through Yukawa-like interactions, can be the leading portal to any fermion propagating into the bulk of the extra dimension and playing the role of dark matter. Moreover, such scalar excitations will necessarily mix with the Higgs boson, leading to modifications of the Higgs couplings and branching ratios, and allowing the Higgs to mediate the coannihilation of the fermionic dark matter. We study these effects and explore the viability of fermionic dark matter in the presence of these new heavy scalar mediators both in the usual freeze-out scenario and in the case where the freeze-out happens during an early period of matter domination.

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Loop-generated neutrino masses in composite Higgs models

Journal of High Energy Physics ◽

10.1007/jhep09(2021)167 ◽

2021 ◽

Vol 2021 (9) ◽

Author(s):

Giacomo Cacciapaglia ◽

Martin Rosenlyst

Keyword(s):

Dark Matter ◽

Neutrino Masses ◽

Composite Higgs ◽

Partial Compositeness ◽

Freeze Out

Abstract We present a composite scotogenic model for neutrino masses, which are generated via loops of ℤ2-odd composite scalars. We consider three different approaches to the couplings of the neutrinos (including three right-handed singlets) and the composite sector: ETC-like four-fermion interactions, fundamental partial compositeness and fermion partial compositeness. In all cases, the model can feature sizeable couplings and remain viable with respect to various experimental constraints if the three ℤ2-odd right-handed neutrinos have masses between the TeV and the Planck scales. Additionally, the lightest ℤ2-odd composite scalar may play the role of Dark Matter, either via thermal freeze-out or as an asymmetric relic. This mechanism can be featured in a variety of models based on vacuum misalignment. For concreteness, we demonstrate it in a composite two-Higgs scheme based on the coset SU(6)/Sp(6).

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