2023-08-05
07:43 |
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2023-06-28
05:47 |
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2023-06-22
06:01 |
The Relation Between KMOC and Worldline Formalisms for Classical Gravity
/ Damgaard, Poul H. (Bohr Inst. ; CERN) ; Hansen, Elias Roos (Bohr Inst.) ; Planté, Ludovic (Bohr Inst.) ; Vanhove, Pierre (IPhT, Saclay)
We demonstrate the equivalence between KMOC and worldline formalisms for classical general relativity, highlighting how the Keldysh-Schwinger in-in formalism is contained in both of them even though the KMOC representation conventionally leads to the evaluation of scattering amplitudes with Feynman propagators. The relationship between the two approaches is illustrated in detail for the momentum kick at second Post-Minkowskian order..
arXiv:2306.11454; CERN-TH-2023-096; IPhT-t23/040; LAPTH-023/23.-
2023-09-11 - 34 p.
- Published in : JHEP 2309 (2023) 059
Fulltext: 2306.11454 - PDF; document - PDF;
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2023-06-22
05:59 |
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2023-06-02
04:05 |
Composing arbitrarily many $SU(N)$ fundamentals
/ Polychronakos, Alexios P. (City Coll., N.Y. ; CUNY, Graduate School - U. Ctr.) ; Sfetsos, Konstantinos (Athens U. ; CERN)
We compute the multiplicity of the irreducible representations in the decomposition of the tensor product of an arbitrary number $n$ of fundamental representations of $SU(N)$, and we identify a duality in the representation content of this decomposition. Our method utilizes the mapping of the representations of $SU(N)$ to the states of free fermions on the circle, and can be viewed as a random walk on a multidimensional lattice. [...]
arXiv:2305.19345; CERN-TH-2023-085.-
2023-08-08 - 25 p.
- Published in : Nucl. Phys. B 994 (2023) 116314
Fulltext: 2305.19345 - PDF; Publication - PDF;
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2023-05-25
04:07 |
Dark Sectors with Mass Thresholds Face Cosmological Datasets
/ Allali, Itamar J. (Tufts U.) ; Rompineve, Fabrizio (CERN ; Barcelona, IFAE ; Barcelona, Autonoma U.) ; Hertzberg, Mark P. (Tufts U.)
Interacting dark sectors may undergo changes in the number of their relativistic species during the early universe, due to a mass threshold $m$ (similar to changes in the Standard Model bath), and in doing so affect the cosmic history. When such changes occur close to recombination, i.e., for $m\sim (0.1-10)~\text{eV}$, the stringent bound on the effective number of neutrino species, $N_{\text{eff}}$, can be relaxed and the value of the Hubble expansion rate $H_0$ inferred from Cosmic Microwave Background (CMB) observations raised. [...]
arXiv:2305.14166; CERN-TH-2023-084.-
2023-07-15 - 36 p.
- Published in : Phys. Rev. D 108 (2023) 023527
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2023-05-05
04:09 |
Precision CMB constraints on eV-scale bosons coupled to neutrinos
/ Sandner, Stefan (Valencia U., IFIC) ; Escudero, Miguel (CERN) ; Witte, Samuel J. (Amsterdam U. ; U. Amsterdam, GRAPPA ; ICC, Barcelona U.)
The cosmic microwave background (CMB) has proven to be an invaluable tool for studying the properties and interactions of neutrinos, providing insight not only into the sum of neutrino masses but also the free streaming nature of neutrinos prior to recombination. The CMB is a particularly powerful probe of new eV-scale bosons interacting with neutrinos, as these particles can thermalize with neutrinos via the inverse decay process, $\nu\bar{\nu} \rightarrow X$, and suppress neutrino free streaming near recombination -- even for couplings as small as $\lambda_\nu \sim \mathcal{O}(10^{-13})$. [...]
arXiv:2305.01692; IFIC/23-13; FTUV-23-0413.0599; CERN-TH-2023-073.-
2023-08-09 - 19 p.
- Published in : Eur. Phys. J. C 83 (2023) 709
Fulltext: 2305.01692 - PDF; document - PDF;
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2023-05-03
04:19 |
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2023-05-03
04:18 |
The Hawking Energy in a Perturbed Friedmann-Lemaître Universe
/ Stock, Dennis (Geneva U., CAP ; Geneva U., Dept. Theor. Phys.) ; Di Dio, Enea (CERN) ; Durrer, Ruth (CERN)
Hawking's quasi-local energy definition quantifies the energy enclosed by a spacelike 2-sphere in terms of the amount of lightbending on the sphere caused by the energy distribution inside the sphere. This paper establishes for the first time a direct connection between the formal mathematical definition of a quasi-local energy and observations, in the context of cosmological perturbation theory. [...]
arXiv:2305.00711; CERN-TH-2023-063.-
2023-08-14 - 28 p.
Fulltext: 2305.00711 - PDF; document - PDF;
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2023-04-29
04:01 |
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