Vincenzo Branchina

University of Catania

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Filippo Contino

University of Catania

P. Finocchiaro

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

C. Agodi

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

L. Calabretta

Carisma Therapeutics (United States)

D. Carbone

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

G. Lanzalone

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

F. Cappuzzello

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

S. Tudisco

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

M. Cavallaro

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

D. Bonanno

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

Cooperative Institutions

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud

137

Istituto Nazionale di Fisica Nucleare

University of Catania

Campbell Collaboration

Istituto Nazionale di Fisica Nucleare, Sezione di Catania

Istituto Nazionale di Fisica Nucleare, Sezione di Torino

Universidad Nacional Autónoma de México

Chinese Academy of Sciences

Centre National de la Recherche Scientifique

Universidade de São Paulo

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Does the Cosmological Constant really indicate the existence of a Dark Dimension?

arXiv (Cornell University) (2023)

Carlo Branchina Vincenzo Branchina Filippo Contino Arcangelo Pernace

According to the "dark dimension" (DD) scenario, we might live in a universe with a single compact extra dimension, whose mesoscopic size is dictated by the measured value of the cosmological constant. This scenario is based on swampland conjectures, that lead to the relation $\rho_{\rm swamp}\sim m_{_{\rm KK}}^4$ between the vacuum energy $\rho_{\rm swamp}$ and the size of the extra dimension $m_{_{\rm KK}}^{-1}$ ($m_{_{\rm KK}}$ is the mass scale of a Kaluza-Klein tower), and on the corresponding result $\rho_{_{\rm EFT}}$ from the EFT limit. We show that $\rho_{_{\rm EFT}}$ contains previously missed UV-sensitive terms, whose presence invalidates the widely spread belief (based on existing literature) that the calculation gives automatically the finite result $\rho_{_{\rm EFT}}\sim m_{_{\rm KK}}^4$ (with no need for fine-tuning). This renders the matching between $\rho_{\rm swamp}$ and $\rho_{_{\rm EFT}}$ a non-trivial issue. We then comment on the necessity to find a mechanism that implements the suppression of the aforementioned UV-sensitive terms. This should finally allow to frame the DD scenario in a self-consistent framework, also in view of its several phenomenological applications based on EFT calculations.

Cosmological constant

Constant (computer programming)

Mesoscopic physics

Effective field theory

10.48550/arxiv.2308.16548

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A COMPARED ANALYSIS OF THE SUSCEPTIBILITY IN THE O(N) THEORY

International Journal of Modern Physics A (2013)

Vincenzo Branchina Emanuele Messina Dario Zappalà

The longitudinal susceptibility $\chi_L$ of the O(N) theory in the broken phase is analyzed by means of three different approaches, namely the leading contribution of the 1/N expansion, the Functional Renormalization Group flow in the Local Potential approximation and the improved effective potential via the Callan-Symanzik equations, properly extended to $d=4$ dimensions through the expansion in powers of $\epsilon=4-d$. The findings of the three approaches are compared and their agreement in the large $N$ limit is shown. The numerical analysis of the Functional Renormalization Group flow equations at small $N$ supports the vanishing of $\chi_L^{-1}$ in $d=3$ and $d=3.5$ but is not conclusive in $d=4$, where we have to resort to the Callan-Smanzik approach. At finite $N$ as well as in the limit $N\to\infty$, we find that $\chi^{-1}_L$ vanishes with $J$ as $J^{\epsilon/2}$ for $\epsilon>0$ and as $(\ln (J))^{-1}$ in $d=4$.

Functional renormalization group

10.1142/s0217751x13500784

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Stability and UV completion of the Standard Model

arXiv (Cornell University) (2015)

Vincenzo Branchina Emanuele Messina

The knowledge of the stability condition of the electroweak (EW) vacuum is of the greatest importance for our understanding of beyond Standard Model (BSM) physics. It is widely believed that new physics that lives at very high energy scales should have no impact on the stability analysis. This expectation has been recently challenged, but the results were controversial as new physics was given in terms of non-renormalizable higher order operators. Here we consider for the first time a renormalizable (toy) UV completion of the SM, and definitely show that such a decoupling does not take place. This result has important phenomenological consequences, providing a very useful test for BSM theories. In particular, it shows that speculations based on the so called criticality do not appear to be well founded.

Decoupling (probability)

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Simultaneous observation of gravitational and electromagnetic waves

arXiv (Cornell University) (2016)

Vincenzo Branchina Manlio De Domenico

Assuming that the short gamma-ray burst detected by the Fermi Gamma-Ray Space Telescope about 0.4 seconds after the gravitational waves observed by the LIGO and VIRGO Collaborations originated from the same black hole merger event, we perform a model-independent analysis of different quantum gravity scenarios based on (modified) dispersion relations (typical of quantum gravity models) for the graviton and the photon. We find that only scenarios where at least one of the two particles is luminal (the other being sub- or super-luminal) are allowed, while scenarios where none of the two particles is luminal are ruled out. Moreover, the physical request of having acceptable values for the quantum gravity scale imposes stringent bounds on the difference between the velocities of electromagnetic and gravitational waves, much more stringent than any previously known bound.

Source

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Citations (7)

Instantons in cutoff theories

Nuclear Physics B (1995)

Vincenzo Branchina János Polonyi

Instanton

Cut-off

Semiclassical physics

Saddle

Non-perturbative

Scale invariance

10.1016/0550-3213(94)00367-n

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Citations (6)

Dark energy and Josephson junctions

Journal of Cosmology and Astroparticle Physics (2009)

Vincenzo Branchina Marco Di Liberto Ivano Lodato

It has been recently claimed that dark energy can be (and has been) observed in laboratory experiments by measuring the power spectrum SI(ω) of the noise current in a resistively shunted Josephson junction and that in new dedicated experiments, which will soon test a higher frequency range, SI(ω) should show a deviation from the linear rising observed in the lower frequency region because higher frequencies should not contribute to dark energy. Based on previous work on theoretical aspects of the fluctuation-dissipation theorem, we carefully investigate these issues and show that these claims are based on a misunderstanding of the physical origin of the spectral function SI(ω). According to our analysis, dark energy has never been (and will never be) observed in Josephson junctions experiments. We also predict that no deviation from the linear rising behavior of SI(ω) will be observed in forthcoming experiments. Our findings provide new (we believe definite) arguments which strongly support previous criticisms.

10.1088/1475-7516/2009/08/011

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Citations (4)

Instability induced renormalization

Physics Letters B (1999)

Jean Alexandre Vincenzo Branchina János Polonyi

Functional renormalization group

Infrared fixed point

Metastability

Tree (set theory)

10.1016/s0370-2693(98)01491-9

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Citations (86)

Effective action and the quantum equation of motion

The European Physical Journal C (2004)

Vincenzo Branchina Hugo Faivre Dario Zappalà

10.1140/epjc/s2004-01895-0

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Citations (9)

The NUMEN Project @ LNS: Status and perspectives

HAL (Le Centre pour la Communication Scientifique Directe) (2018)

F. Cappuzzello C. Agodi L. Acosta P. Amador-Valenzuela N. Auerbach

10.1393/ncc/i2019-19057-2

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Mini-Instantons

arXiv (Cornell University) (1994)

Vincenzo Branchina János Polonyi

It is shown that the inhomogeneous saddle points of scale invariant theories make the semiclassical expansion sensitive on the choice of non-renormalizable operators. In particular, the instanton fugacity and the beta function of the two dimensional non-linear sigma model depends on apparently non-renormalizable operators. This represents a non-perturbative breakdown of that concept of universality which is based on low dimensional operators.

Instanton

Semiclassical physics

Sigma

Saddle

Sigma model

Non-perturbative

Saddle point

10.48550/arxiv.hep-th/9401079

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