Helical magnetic fields from Riemann coupling lead to baryogenesis

Kushwaha, Ashu; Shankaranarayanan, S.

doi:10.1103/physrevd.104.063502

Cited by 7 publications

(7 citation statements)

References 55 publications

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“…This leads to the following crucial question: Is there a set of unique signatures that distinguish MG theories from GR? This section investigates this issue by considering three specific cases: Testing MG theories using gravitational wave (GW) observations [112][113][114][115][116], low-energy observational signatures in cosmological observations [117] and non-minimal coupling of electromagnetic fields leading to observable signatures [118][119][120].…”

Section: What Are the Observational Consequences?mentioning

confidence: 99%

“…Since both require physics beyond the standard model, there is a tantalizing possibility that the same physics can solve both problems. Recently, it was shown that non-minimal coupling of the electromagnetic field with the Riemann tensor could potentially explain magnetogenesis and baryogenesis [118,119].…”

Section: What Are the Observational Consequences?mentioning

confidence: 99%

“…Interestingly, the generation of the non-zero primordial helical magnetic fields leads to a chiral anomaly, which results in the imbalance between left and right-handed fermions. In the presence of an electromagnetic field in curved space-time, the chiral anomaly is given by the following equation [119]:…”

Section: What Are the Observational Consequences?mentioning

confidence: 99%

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Modified theories of Gravity: Why, How and What?

Shankaranarayanan,

Johnson

2022

Preprint

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General Relativity (GR) was proven via the direct detection of gravitational waves from the mergers of the binary black holes and binary neutron stars by the Advanced LIGO and Advanced Virgo detectors. These detections confirmed the prediction of GR and provided the first direct evidence of the existence of stellar-mass black holes (BHs). However, the occurrence of singularities at the centers of BHs suggests that GR is inapplicable because of the breakdown of the equivalence principle at the singularities. The fact that these singularities exist indicates that GR cannot be a universal theory of space-time. In the low-energy limit, the theoretical and observational challenges faced by the ΛCDM model also indicate that we might have to look beyond GR as the underlying theory of gravity. Unlike GR, whose field equations contain only up to second-order derivatives, the modified theories with higher derivative Ricci/Riemann tensor gravity models include higher derivatives. Therefore, one expects significant differences between GR and modified theories. Since there are many ways of modifying GR in the strong-gravity and cosmological distances, each model has unique features. This leads to the following crucial question: Are there a set of unique signatures that distinguish GR from modified gravity (MG) theories? This review discusses three aspects of MG theories: (1) Why do we need to consider MG theories? (2) How to modify GR? and (3) What are the observational consequences? The review is written in a pedagogical style with the expectation that it will serve as a useful reference for theorists and observers and those interested in bridging the divide between theory and observations.

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Section: What Are the Observational Consequences?mentioning

confidence: 99%

Section: What Are the Observational Consequences?mentioning

confidence: 99%

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Modified theories of Gravity: Why, How and What?

Shankaranarayanan,

Johnson

2022

Preprint

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“…Both generation scenarios, inflationary and phase-transitional, could generate helical PMFs (see the seminal work of Cornwall 1997, andVachaspati 2021 for a review and references therein). The relevance of a primordial, helical magnetic field is that, if ever detected, it will be a direct indication of parity (mirror symmetry) violation in the early universe and can in turn explain the matter-antimatter asymmetry (see Giovannini &Shaposhnikov 1998 andVachaspati 2001 for pioneering work, and the recent work of Fujita &Kamada 2016 andKushwaha &Shankaranarayanan 2021).…”

Section: Introductionmentioning

confidence: 99%

Evolution of Primordial Magnetic Fields during Large-scale Structure Formation

Mtchedlidze

Domínguez-Fernández

Brandenburg

et al. 2022

ApJ

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Primordial magnetic fields (PMFs) could explain the large-scale magnetic fields present in the universe. Inflation and phase transitions in the early universe could give rise to such fields with unique characteristics. We investigate the magnetohydrodynamic evolution of these magnetogenesis scenarios with cosmological simulations. We evolve inflation-generated magnetic fields either as (i) uniform (homogeneous) or as (ii) scale-invariant stochastic fields, and phase-transition-generated ones either as (iii) helical or as (iv) nonhelical fields from the radiation-dominated epoch. We find that the final distribution of magnetic fields in the simulated cosmic web shows a dependence on the initial strength and the topology of the seed field. Thus, the observed field configuration retains information on the initial conditions at the moment of the field generation. If detected, PMF observations would open a new window for indirect probes of the early universe. The differences between the competing models are revealed on the scale of galaxy clusters, bridges, as well as filaments and voids. The distinctive spectral evolution of different seed fields produces imprints on the correlation length today. We discuss how the differences between rotation measures from highly ionized regions can potentially be probed with forthcoming surveys.

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“…The origin of the seed magnetic field remains an open-ended subject in current cosmology, despite having so many fundamental impacts. The pervasive magnetic fields are anticipated to have a significant impact on a variety of processes, including baryogenesis Giovannini & Shaposhnikov (1998); Simone et al (2011); Kushwaha & Shankaranarayanan (2021), primordial nucleosynthesis Grasso & Rubinstein (1996), structure formation Sethi & Subramanian (2005); Kahniashvili et al (2013); Katz et al (2021), and cosmic microwave background physics Barrow et al (1997); Yamazaki et al (2010); Kunze & Komatsu (2015) (for more details, see the review article Grasso & Rubinstein (2001)). In reference Berezhiani et al (2013), authors have discussed the origin of these fields during galaxy formation, when a finite interaction between the baryons and DM particles is considered.…”

Section: Introductionmentioning

confidence: 99%

Thermal SZ effect in a magnetized IGM dominated by interacting DM decay/annihilation during dark ages

Pandey¹,

Malik²

2022

Preprint

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During cosmic dawn, the thermal history of the universe is well studied, and a study of this era can give us some of the most useful insight into the universe before the recombination epoch. Its precise modeling and future high-precision measurements will be a valuable tool for determining the thermal history of the universe. In the present work, we study the thermal and ionization history of IGM in the presence of decaying magnetic fields via ambipolar and turbulent decay, Baryon-Dark matter (BDM) interaction, including the DM decay/annihilation. The BDM interaction cross-sections considered are of the form 𝜎 = 𝜎 0 𝑣 𝑛 , where 𝑛 = −2 and 𝑛 = −4. In this work, we show that in the current scenario, the decay/annihilation of the DM particles have a considerable impact on the temperature and ionization histories at low redshift. With the addition of the concept of fractional interaction, which states that if a fraction of the DM particles interacts with the baryons, the temperature and ionization fraction of the baryons show a strong dependence on the percentage of DM particles interacting with the baryons. We have also studied the interesting consequences of the present scenario on the thermal Sunyaev-Zeldovich (tSZ) effect. We show that the highest value of the absolute value of the mean 𝑦−parameter in the current DM decay/annihilation scenario is well within the values derived from experimental data such as PLANCK, FIRAS, and PIXIE. Later we calculate the bound on the ordinary magnetic fields originating from the Dark photons.

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Helical magnetic fields from Riemann coupling lead to baryogenesis

Cited by 7 publications

References 55 publications

Modified theories of Gravity: Why, How and What?

Modified theories of Gravity: Why, How and What?

Evolution of Primordial Magnetic Fields during Large-scale Structure Formation

Thermal SZ effect in a magnetized IGM dominated by interacting DM decay/annihilation during dark ages

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