HEP Phenomenology·hep-ph

Fri·Jul 15, 2022Friday·July 15, 2022

27 papers—23 primary·4 cross-listed·reconstructed*

01*
Phenomenological Implications of a Magnetic 5th Force
Dennis E. Krause🇺🇸 · Joseph Bertaux🇺🇸 · A. Meenakshi McNamara🇺🇸 · John T. Gruenwald🇺🇸 · Andrew Longman🇺🇸 · Carol Y. Scarlett🇺🇸 · Ephraim Fischbach🇺🇸
A 5th force coupling to baryon number $B$ has been proposed to account for the correlations between the acceleration differences $Δ a_{ij}$ of the samples studied in the Eötvös experiment, and the corresponding differences in the baryon-to-mass ratios $Δ (B / μ)_{ij}$ . To date the Eötvös results have not been supported by modern experiments. Here we investigate the phenomenological implications of a possible magnetic analog $B_{5}$ of the conventional 5th force electric field, $E_{5}$ , arising from the Earth's rotation. We demonstrate that, in the presence of couplings proportional to $B_{5}$ , both the magnitude and direction of a possible 5th force field could be quite different from what would otherwise be expected and warrants further investigation.
hep-phgr-qcphysics.class-phInt.J.Mod.Phys.A(2023)·1 citation
02*
Comments on collinear factorization
George Sterman🇺🇸
In this short review, I'll discuss the background, applicability and prospects of collinear factorization in quantum chromodynamics.
hep-ph11 citations
03*
Pseudo-scalar mesons: light front wave functions, GPDs and PDFs
L. Albino🇲🇽 · I. M. Higuera-Angulo🇲🇽 · K. Raya🇪🇸 · A. Bashir🇲🇽
We develop a unified algebraic model which satisfactorily describes the internal structure of pion and kaon as well as heavy quarkonia ( $η_{c}$ and $η_{b}$ ). For each of these mesons, we compute their generalized parton distributions (GPDs), built through the overlap representation of their light-front wave function, tightly constrained by the modern and precise knowledge of their quark distribution amplitudes. From this three-dimensional knowledge of mesons, we deduce parton distribution functions (PDFs) as well as electromagnetic form factors and construct the impact parameter space GPDs. The PDFs for mesons formed with light quarks are then evolved from the hadronic scale of around 0.3 GeV to 5.2 GeV, probed in experiments. We make explicit comparisons with experimental results available and with earlier theoretical predictions.
hep-phnucl-thPRD(2022)·33 citations
04*
Searching for the charged-current non-standard neutrino interactions at the $e^{-} p$ colliders
Chongxing Yue · Xuejia Cheng · Yueqi Wang · Yanyu Li
Considering the theoretical constraints on the charged-current (CC) non-standard neutrino interaction (NSI) parameters in a simplified $W^{'}$ model, we study the sensitivities of the Large Hadron electron Collider (LHeC) and Future Circular Collider-hadron electron (FCC-he) to the CC NSI parameters through the subprocess $e^{-} q \to W^{'} \to v_{e} q^{'}$ . Our results show that the LHeC with $L = 100 fb^{- 1}$ is a little more sensitive to the CC NSI parameters than that of the high-luminosity (HL) LHC, and the absolute values of the lower limits on the CC NSI parameters at the FCC-he are smaller than those of the HL-LHC about two orders of magnitude.
hep-phNPB(2022)·2 citations
05*
Testing the scalar sector of the Standard-Model Extension with neutron gravity experiments
C. A. Escobar🇲🇽 · A. Martín-Ruiz🇲🇽 · A. M. Escobar-Ruiz🇲🇽 · Román Linares🇲🇽
In the present study we analyse, within the scalar sector of the Standard-Model Extension (SME) framework, the influence of a spontaneous Lorentz symmetry breaking on gravitational quantum states of ultracold neutrons. The model is framed according to the laboratory conditions of the recent high-sensitivity GRANIT and $q$ Bounce experiments. The high-precision data achieved in such experiments allow us to set bounds on the symmetry breaking parameters of the model. The effective Hamiltonian governing the neutron's motion along the axis of free fall is derived explicitly. It describes a particle in a gravitational field with an effective gravitational constant controlled non-trivially by the Lorentz-violating parameters. In particular, using the exact wave functions and the energy spectrum, we evaluate both the heights associated with the quantum states and the transition frequencies between neighborhoring quantum states. By comparing our theoretical results with those reported in the GRANIT and the $q$ Bounce experiments, upper bounds on the Lorentz-violating parameters are determined. We also consider for the first time the gravity-induced interference pattern in a COW-type experiment to test Lorenz-invariance. In this case, an upper bound for the parameters is established as well.
hep-phEur.Phys.J.Plus(2022)·5 citations
06*
Massive form factors at $O (α_{s}^{3})$
Kay Schönwald🇩🇪
We report on our recent calculation of massive quark form factors using a semi-numerical approach based on series expansions of the master integrals around singular and regular kinematic points and numerical matching. The methods allows to cover the whole kinematic range of negative and positive values of the virtuality $s$ with at least seven significant digits accuracy.
hep-phPoS(2022)·2 citations
07*
$Q Q ˉ$ $(Q \in {b, c})$ spectroscopy using the modified Rovibrational model
Zheng-Yuan Fang🇨🇳 · Ya-Rong Wang🇨🇳 · Cheng-Qun Pang🇨🇳
Mass spectra of quarkonium systems can be described by different phenomenological potentials. In the present work, the {\color{black}resonance} states of heavy quarkonium like ( $c c ˉ$ and $b b ˉ$ ) are considered as the rovibrational states. We study a parameterized rovibrational model derived from the empirical solution of the nonrelativistic Schrödinger equation with Morse potential, the corrections are composed of colour hyperfine interaction and spin-orbit interaction of mesons. We {\color{black}obtain} the high excited state mass spectra of charmonium and bottomonium comparing the results in reasonable agreement with the present experimental data.
hep-phPhys.Part.Nucl.Lett.(2023)·2 citations
08*
System of excited monopole-antimonopole pair in the Weinberg-Salam model
Dan Zhu🇲🇾 · Khai-Ming Wong🇲🇾 · Guo-Quan Wong🇲🇾
We investigate further the properties of axially symmetric monopole-antimonopole pair in the standard Weinberg-Salam model. By using a novel data sampling approach, we have obtained and analyzed 300 numerical solutions corresponding to physical Higgs self-coupling $β = 0.7782$ and the Weinberg angle $tan θ_{W} = 0.5358$ . We calculate the energy of these solutions and confirm that they reside in a range of 13.1690 - 21.0221 TeV. In addition, a unique pattern is shown when the data are arranged according to an algorithm based on the system's symmetry, which seems to indicate the system is oscillating. We also calculate numerically the magnetic charge of the solutions and confirm that their values are indeed $\pm \frac{4 π}{e} sin^{2} θ_{W}$ .
hep-ph0 citations
09*
Flavor Changing Neutral Currents in the Higgs Sector
Marc Sher🇺🇸
This review considers models with extended Higgs sectors in which there are tree-level flavor-changing neutral currents (FCNC) mediated by scalars. After briefly reviewing models without tree-level FCNC, several models with such currents are discussed. A popular mass-matrix ansatz, in which the flavor-changing couplings are the geometric mean of the individual flavor couplings, is presented. While it provided a target for experimentalists for three decades, it in now being severely challenged by experiments. Couplings expected to be of O(1) must be substantially smaller and the ansatz is now not favored. The minimal flavor violation hypothesis is introduced. Then specific models are presented, including the Branco-Grimus-Lavoura models. These models are not yet excluded experimentally, but they are highly predictive and will be tested once heavy Higgs bosons are discovered. We then turn to flavorful models and flavor-changing decays of heavy Higgs bosons, and it is shown that in many of these models, the heavy Higgs could predominantly decay in a flavor-changing manner (such as $c t$ or $μτ$ ) and experimentalists are encouraged to include these possibilities in their searches.
hep-phMod.Phys.Lett.A(2022)·11 citations
10*
Determining Neutrino Mass Ordering with ICAL, JUNO and T2HK
Deepak Raikwal🇮🇳 · Sandhya Choubey🇸🇪 · Monojit Ghosh🇮🇳
In this paper we study the synergy among the future accelerator (T2HK), future atmospheric (ICAL) and future reactor (JUNO) neutrino experiments to determine the neutrino mass ordering. T2HK can measure the mass ordering only for favorable values of $δ_{CP}$ , whereas the mass ordering sensitivity of JUNO is dependent on the energy resolution. Our results show that with a combination of T2HK, ICAL and JUNO one can have a mass ordering sensitivity of 7.2 $σ$ even for the unfavorable value of $δ_{CP} = 0^{\circ}$ for T2HK and most conservative value of JUNO energy resolution of 5 $%/ E (M e V)$ . The synergy mainly comes because different oscillation channels prefer different values of $∣Δ m_{31}^{2} ∣$ in the fit when the mass-ordering $χ^{2}$ is minimized. In this context we also study: (i) effect of varying energy resolution of JUNO, (ii) the effect of longer run-time of ICAL, (iii) effect of different true values of $θ_{23}$ and (iv) effect of octant degeneracy in the determination of neutrino mass ordering.
hep-phhep-exEur.Phys.J.Plus(2023)·7 citations
11*
Deeply-virtual Compton scattering at the next-to-next-to-leading order
V. M. Braun🇩🇪 · Yao Ji🇩🇪 · Jakob Schoenleber🇩🇪
Deeply-virtual Compton scattering gives access to the generalized parton distributions that encode the information on the transverse position of quarks and gluons in the proton in dependence in their longitudinal momentum. In anticipation of the high-precision experimental data in a broad kinematic range from the Electron-Ion Collider, we have calculated the two-loop, next-to-next-to-leading (NNLO) DVCS coefficient functions associated with the dominant Compton form factors $H$ and $E$ at large energies. The NNLO correction to the imaginary part of $H$ appears to be rather large, up to factor two at the input scale $Q^{2} = 4$ GeV $^{2}$ for simple GPD models, due to a cancellation between quark and gluon contributions.
hep-phPRL(2022)·37 citations
12*
Fatjet signatures of heavy neutrinos and heavy leptons in a left-right model with universal seesaw at the HL-LHC
Atri Dey🇮🇳 · Rafiqul Rahaman🇮🇳 · Santosh Kumar Rai🇮🇳
We perform a collider search for fatjet signals originating from boosted heavy neutral and charged leptons with masses between a few hundred GeV to a TeV. These heavy leptons originate from the decay of heavy gauge bosons with masses above 4 TeV in a left-right symmetric extension of the Standard Model (SM), which considers a universal seesaw mechanism for the generation of all the SM fermion masses. The fatjet signals arise naturally in this model due to the presence of heavy seesaw partners of the SM fermions which decay to SM gauge bosons carrying large boosts. We employ substructure based variables lepton sub-jet fraction ( $L S F$ ) and lepton mass drop ( $L M D$ ) together with kinematic variables of fatjets to look for fatjet signals associated with non-isolated leptons. These variables help in reducing the SM backgrounds while retaining enough statistics for signal events, which leads to a robust discovery potential at the high-luminosity Large Hadron Collider (HL-LHC).
hep-phhep-exEPJC(2024)·6 citations
13*
Detecting axion dark matter with chiral magnetic effects
Deog Ki Hong🇰🇷 · Sang Hui Im🇰🇷 · Kwang Sik Jeong🇰🇷 · Dong-han Yeom🇰🇷
We show that dark matter axions or axion-like particles (ALP) induce spontaneously alternating electric currents in conductors along the external magnetic fields due to the (medium) axial anomaly, realizing the chiral magnetic effects (CME). We propose a new experiment to measure this current to detect the dark matter axions or ALP. These induced currents are the electron medium effects, directly proportional to the axion or ALP coupling to electrons, which depends on their microscopic physics. In the experimental setup one measures the sum of the electric current due to CME and the vacuum current due to the anomalous axion-photon coupling. The CME current is in general subdominant by a factor of the Fermi velocity of electrons, compared to latter, unless the axion or ALP coupling to electrons is much bigger than its coupling to photons to compensate the Fermi velocity suppression. However, we find that repurposing the currently operating and planned axion haloscopes may have good sensitivity to probe the CME current.
hep-phPRD(2024)·10 citations
14*
Dark Sector Studies with Neutrino Beams
Brian Batell🇺🇸 · Joshua Berger🇺🇸 · Vedran Brdar🇺🇸 · Alan D. Bross🇺🇸 · Janet M. Conrad🇺🇸 · Patrick deNiverville🇺🇸 · Valentina De Romeri🇪🇸 · Bhaskar Dutta🇺🇸 · Saeid Foroughi-Abari🇨🇦 · Matheus Hostert🇬🇧 · Joshua Isaacson🇺🇸 · Ahmed Ismail🇺🇸 and 20 other authors
An array of powerful neutrino-beam experiments will study the fundamental properties of neutrinos with unprecedented precision in the coming years. Along with their primary neutrino-physics motivations, there has been growing recognition that these experiments can carry out a rich program of searches for new, light, weakly-coupled particles that are part of a dark sector. In this white paper, we review the diverse theoretical motivations for dark sectors and the capabilities of neutrino beam experiments to probe a wide range of models and signatures. We also examine the potential obstacles that could limit these prospects and identify concrete steps needed to realize an impactful dark sector search program in this and coming decades.
hep-phhep-ex43 citations
15*
Exploring Dark Sector Portals with High Intensity Experiments
Brian Batell🇺🇸 · Nikita Blinov🇨🇦 · Christopher Hearty🇨🇦 · Robert McGehee🇺🇸
A broad program of searches at high intensity experiments during the coming decade and beyond will sensitively probe new light mediator particles interacting through the minimal renormalizable vector, Higgs, and neutrino portals as well as higher-dimension axion-like particle portals. These portals may link the visible and dark sectors and play a critical role in many proposed solutions to some of the big open questions in particle physics and cosmology. In this whitepaper, we survey the theoretical and experimental progress, status, and prospects in the study of minimal dark sector portals.
hep-phastro-ph.COhep-ex73 citations
16*
Condensed dark matter with a Yukawa interaction
Raghuveer Garani🇮🇹 · Michel H.G. Tytgat🇧🇪 · Jérôme Vandecasteele🇩🇪
We explore the possible phases of a condensed dark matter (DM) candidate taken to be in the form of a fermion with a Yukawa coupling to a scalar particle, at zero temperature but at finite density. This theory essentially depends on only four parameters, the Yukawa coupling, the fermion mass, the scalar mediator mass, and the DM density. At low fermion densities we delimit the Bardeen-Cooper-Schrieffer (BCS), Bose-Einstein Condensate (BEC) and crossover phases as a function of model parameters using the notion of scattering length. We further study the BCS phase by consistently including emergent effects such as the scalar density condensate and superfluid gaps. Within the mean field approximation, we derive the consistent set of gap equations, retaining their momentum dependence, and valid in both the non-relativistic and relativistic regimes. We present numerical solutions to the set of gap equations, in particular when the mediator mass is smaller and larger than the DM mass. Finally, we discuss the equation of state (EoS) and possible astrophysical implications for asymmetric DM.
hep-phastro-ph.COhep-thnucl-thPRD(2022)·29 citations
17*
Breakup corrections to the $^{3}$ He beam polarization measurements at the future BNL Electron Ion Collider
A. A. Poblaguev🇺🇸
Requirements for hadron polarimetry at the future Electron-Ion Collider (EIC) include measurements of absolute $^{3} He (h)$ beam polarization with systematic uncertainties better than $σ_{P}^{syst} / P ≲ 1%$ . Due to the successful use, since 2005, of the polarized hydrogen jet target polarimeter (HJET) to measure proton beam polarization at the Relativistic Heavy Ion Collider (RHIC), the HJET technique promises to be suitable for the $^{3} He$ polarimetry at EIC. For that, however, one needs to know the ratio of the $h^{↑} p$ and $p^{↑} h$ analyzing powers. For elastic scattering, this ratio can be evaluated with sufficient accuracy if $p^{↑} p$ analyzing power is precisely known. In this paper, the deuteron beam data acquired at HJET in RHIC Run 16 was used to evaluate corrections to the measured helion beam polarization due to the $^{3} He$ breakup. The breakup effect was found to be negligible if the ratio of the beam and target (jet) single spin asymmetries are concurrently measured to determine the $^{3} He$ beam polarization.
hep-phPRC(2022)·8 citations
18*
Right-handed Dirac and Majorana neutrinos at Belle II
Tao Han🇺🇸 · Jiajun Liao🇨🇳 · Hongkai Liu🇮🇱 · Danny Marfatia🇺🇸
We assess the ability of the Belle II experiment to probe the Dirac or Majorana nature of a massive right-handed neutrino (RHN) $N$ in the MeV to GeV mass range. We consider the production and decay of RHNs to proceed via new interactions described by the standard model effective field theory (SMEFT) extended with right-handed neutrino fields (SMNEFT), and not via mass mixing with active neutrinos. We find that Belle II has the potential to discover $N$ if kinematically accessible. We perform detailed simulations of the angular distributions of lepton pairs from the decay of $N$ produced in two-body and three-body decays of $B$ mesons. We show that for $m_{N}$ above 100 MeV, Belle II can distinguish between Dirac and Majorana neutrinos at more than the 5 $σ$ CL for most operators, and the combination of the production and decay operators can be identified from the subsequent decay of the heavy neutrino. Also, the production operators can be identified using three-body $B$ meson decay for any $m_{N}$ if the $B \to D ℓ N$ and $B \to D^{*} ℓ N$ events can be well separated.
hep-phhep-exJHEP(2023)·9 citations
19*
Strange processes in general two Higgs doublet model
Wei-Shu Hou🇹🇼 · Girish Kumar🇹🇼
In the general two Higgs doublet model (g2HDM) that has extra Yukawa couplings, we analyze their New Physics (NP) contributions to kaon mixing parameter $ε_{K}$ , direct CP violation parameter $ε^{'} / ε$ , and rare $K^{+} \to π^{+} ν ν ˉ$ , $K_{L} \to π^{0} ν ν ˉ$ , and $K_{L, S} \to μ^{+} μ^{-}$ decays. We study correlations between these observables, and call special attention to a unique complementarity of kaon mixing and rare $K \to π ν ν ˉ$ decays in probing the exotic Higgs mass spectrum of g2HDM. The importance of kaon physics in probing NP vis-à-vis B physics is stressed. One unexpected feature we uncover is the special sensitivity of $K^{+} \to π^{+} ν ν ˉ$ to TeV scale charged Higgs boson.
hep-phJHEP(2022)·7 citations
20*
Quark and gluon two-loop beam functions for leading-jet $p_{T}$ and slicing at NNLO
Samuel Abreu🇨🇭 · Jonathan R. Gaunt🇬🇧 · Pier Francesco Monni🇨🇭 · Luca Rottoli🇨🇭 · Robert Szafron🇺🇸
We compute the complete set of two-loop beam functions for the transverse momentum distribution of the leading jet produced in association with an arbitrary colour-singlet system. Our results constitute the last missing ingredient for the calculation of the jet-vetoed cross section at small veto scales at the next-to-next-to-leading order, as well as an important ingredient for its resummation to next-to-next-to-next-to-leading logarithmic order. Our calculation is performed in the soft-collinear effective theory framework with a suitable regularisation of the rapidity divergences occurring in the phase-space integrals. We discuss the occurrence of soft-collinear mixing terms that might violate the factorisation theorem, and demonstrate that they are naturally absorbed into the beam functions at two loops in the exponential rapidity regularisation scheme when performing a multipole expansion of the measurement function. As in our recent computation of the two-loop soft function, we present the results as a Laurent expansion in the jet radius $R$ . We provide analytic expressions for all flavour channels in $x$ space with the exception of a set of $R$ -independent non-logarithmic terms that are given as numerical grids. We also perform a fully numerical calculation with exact $R$ dependence, and find that it agrees with our analytic expansion at the permyriad level or better. Our calculation allows us to define a next-to-next-to-leading order slicing method using the leading-jet $p_{T}$ as a slicing variable. As a check of our results, we carry out a calculation of the Higgs and $Z$ boson total production cross sections at the next-to-next-to-leading order in QCD.
hep-phJHEP(2023)·21 citations
21*
Fiducial Drell-Yan production at the LHC improved by transverse-momentum resummation at N $^{4}$ LL+N $^{3}$ LO
Tobias Neumann🇺🇸 · John Campbell🇺🇸
Drell-Yan production is one of the precision cornerstones of the LHC, serving as calibration for measurements such as the $W$ -boson mass. Its extreme precision at the level of 1% challenges theory predictions at the highest level. We present the first independent calculation of Drell-Yan production at order $α_{s}^{3}$ in transverse-momentum ( $q_{T}$ ) resummation improved perturbation theory. Our calculation reaches the state-of-the-art through inclusion of the recently published four loop rapidity anomalous dimension and three loop massive axial-vector contributions. We compare to the most recent data from CMS with fiducial and differential cross-section predictions and find excellent agreement at the percent level. Our resummed calculation including the matching to $Z$ +jet production at NNLO is publicly available in the upcoming CuTe-MCFM 10.3 release and allows for theory-data comparison at an unprecedented level.
hep-phhep-exPRD(2023)·108 citations
22*
Non-metricity signatures on the Higgs boson signal strengths at the LHC
Victor Ilisie🇪🇸
In this work we study the high-energy Higgs boson phenomenology associated to the non-metricity scale $Λ_{Q}$ at the LHC. Non-metricity is present in more generic non-Riemannian geometries describing gravity beyond General Relativity and exhibits nice features in astronomy and cosmology, and it can be analysed perturbatively. Using effective field theory tools, we calculate the new physics contributions to the one-loop $H \to γ γ$ and $g g \to H$ processes and, together with previous bounds from Compton scattering, we obtain relevant constraints and correlations in the model's parameter space. This can help us take a step further, and no longer associate gravitational effects uniquely to astronomical phenomena, and to start analysing these effects by means of high energy experiments. In turn, this could also help us get a better grasp at quantum phenomena associated to gravity.
hep-phgr-qchep-thJHEP(2022)·2 citations
23*
Catastrogenesis: DM, GWs, and PBHs from ALP string-wall networks
Graciela B. Gelmini🇺🇸 · Anna Simpson🇺🇸 · Edoardo Vitagliano🇺🇸
Axion-like particles (ALPs), a compelling candidate for dark matter (DM), are the pseudo Nambu-Goldstone bosons of a spontaneously and explicitly broken global $U (1)$ symmetry. When the symmetry breaking happens after inflation, the ALP cosmology predicts the formation of a string-wall network which must annihilate early enough, producing gravitational waves (GWs) and primordial black holes (PBHs), as well as non-relativistic ALPs. We call this process catastrogenesis. We show that, under the generic assumption that the potential has several degenerate minima, GWs from string-wall annihilation at temperatures below 100 eV could be detected by future CMB and astrometry probes, for ALPs with mass from $1 0^{- 16}$ to $1 0^{6} eV$ . In this case, structure formation could limit ALPs to constitute a fraction of the DM and the annihilation would produce mostly ``stupendously large" PBHs. For larger annihilation temperatures, ALPs can constitute $100%$ of DM, and the annihilation could produce supermassive black holes with a mass of up to $1 0^{9} M_{⊙}$ as found at the center of large galaxies. Therefore our model could solve two mysteries, the nature of the DM and the origin of these black holes.
hep-phastro-ph.COJCAP(2023)·58 citations
24*
Rates of particle production in $R^{2}$ gravity and supersymmetry-kind dark matter
E.V. Arbuzova🇷🇺 · A.D. Dolgov🇷🇺
Universe heating in $R^{2}$ -modified gravity is considered. The rates of particle production by the scalaron are calculated for different decay channels. Freezing of massive stable relics with the interaction strength typical for supersymmetry is studied. It is shown that the bounds on masses of supersymmetry-kind particles allowing them to form the cosmological dark matter (DM)depend upon the dominant decay mode of the scalaron. In any case the results presented open much wider mass window for DM with the interaction strength typical for supersymmetry.
↳ astro-ph.COgr-qchep-ph0 citations
25*
Trace anomaly as signature of conformality in neutron stars
Yuki Fujimoto🇺🇸 · Kenji Fukushima🇯🇵 · Larry D. McLerran🇺🇸 · Michal Praszalowicz🇵🇱
We discuss an interpretation that a peak in the sound velocity in neutron star matter, as suggested by the observational data, signifies strongly-coupled conformal matter. The normalized trace anomaly is a dimensionless measure of conformality leading to the derivative and the non-derivative contributions to the sound velocity. We find that the peak in the sound velocity is attributed to the derivative contribution from the trace anomaly that steeply approaches the conformal limit. Smooth continuity to the behavior of high-density QCD implies that the matter part of the trace anomaly may be positive definite. We discuss a possible implication of the positivity condition of the trace anomaly on the $M$ - $R$ relation of the neutron stars.
↳ nucl-thastro-ph.HEhep-phPRL(2022)·183 citations
26*
Equation of state of the running vacuum
Cristian Moreno-Pulido🇪🇸 · Joan Sola Peracaula🇪🇸
Recent studies of quantum field theory in FLRW spacetime suggest that the cause of the speeding up of the universe is the running vacuum (RV). Appropriate renormalization of the energy-momentum tensor shows that the vacuum energy density is a smooth function of the Hubble rate and its derivatives: $ρ_{vac} = ρ_{vac} (H, H ˙, H ¨, ...)$ . This is because in QFT the quantum scaling of $ρ_{vac}$ with the renormalization point turns into cosmic evolution with $H$ . As a result, any two nearby points of the cosmic expansion during the standard FLRW epoch are smoothly related through $δ ρ_{vac} \sim O (H^{2})$ . In our approach, what we call the `cosmological constant' $Λ$ is just the nearly sustained value of $8 π G (H) ρ_{vac} (H)$ around (any) given epoch, where $G (H)$ is the running gravitational coupling. In the present study, after summarizing the main QFT calculations supporting the RV approach, we focus on the calculation of the equation of state (EoS) of the RV for the entire cosmic history within such a QFT framework. In particular, in the very early universe, where higher (even) powers $ρ_{vac} \sim O (H^{N})$ ( $N = 4, 6, \dots$ ) triggered inflation during a short period in which $H =$ const, the vacuum EoS is very close to $w_{vac} = - 1$ . This ceases to be true during the FLRW era, where it adopts the EoS of matter during the relativistic ( $w_{vac} = 1/3$ ) and non-relativistic ( $w_{vac} = 0$ ) epochs. Interestingly enough, we find that in the late universe the EoS becomes mildly dynamical and mimics quintessence, $w_{vac} ≳ - 1$ . It finally asymptotes to $- 1$ in the remote future, but in the transit the RV helps alleviating the $H_{0}$ and $σ_{8}$ tensions.
↳ gr-qcastro-ph.COhep-phhep-thEPJC(2022)·61 citations
27*
Mass-induced confinement near the sill of the conformal window
Roman Marcarelli🇺🇸 · Nicholas Miesch🇺🇸 · Ethan T. Neil🇺🇸
We revisit standard arguments for hyperscaling of the spectrum when a non-zero fermion mass is introduced to a gauge-fermion theory which is conformal in the infrared limit. With some general assumptions, we argue that the induced confinement scale will be significantly enhanced near the edge of the conformal to confining transition. This enhancement can allow for the fermion mass to be arbitrarily small compared to the confinement scale. This scale separation may allow for apparent spontaneous breaking of chiral symmetry within the conformal window, which may be of interest for construction of dilaton effective field theories in this regime.
↳ hep-thhep-lathep-phPRD(2023)·2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.