HEP Phenomenology·hep-ph

Thu·Jul 21, 2022Thursday·July 21, 2022

30 papers—19 primary·11 cross-listed·reconstructed*

01*
Neutrino spin-flavour precession in magnetized white dwarf
Jyotismita Adhikary🇮🇳 · Ashutosh Kumar Alok🇮🇳 · Arindam Mandal🇮🇳 · Trisha Sarkar🇮🇳 · Shreya Sharma🇮🇳
Due to notoriously small value of the neutrino magnetic moment, the phenomena of neutrino spin flavour precession (SFP) requires very high magnetic field. This makes only a handful of systems suitable to study this phenomena. By the observation of SFP, the Dirac and Majorana nature of neutrinos is expected to be distinguished. In this work, we point out the potential of white dwarf (WD) system in studying the spin-flavour oscillation of neutrinos. From recent analysis, it has been found that young isolated WDs may harbor very strong internal magnetic field, even without exhibiting any surface magnetic field. The presence of magnetic field enhances the cooling process and along with that, renders the spin-flavour oscillation of neutrinos emitted in the neutrino cooling process. Employing the standard WD specifications, we analyse whether a magnetized WD is a suitable environment to distinguish between the Dirac and Majorana nature of neutrino. Lower value of spin flavour transition probability implies reduced active neutrino flux which is possible to be estimated in terrestrial neutrino detectors. We find that the spin flavour transition probability of Dirac neutrinos is much higher in comparison to the Majorana neutrino which converts the active neutrino flavours to sterile in a significant amount. We also examine the sensitivity of the spin flavour transition probability to the neutrino magnetic moment.
hep-phastro-ph.HEJ.Phys.G(2023)·4 citations
02*
Matching generalised transverse-momentum-dependent distributions onto generalised parton distributions at one loop
Valerio Bertone🇫🇷
The operator definition of generalised transverse-momentum-dependent (GTMD) distributions is exploited to compute for the first time the full set of one-loop corrections to the off-forward matching functions. These functions allow one to obtain GTMDs in the perturbative regime in terms of generalised parton distributions (GPDs). In the unpolarised case, non-perturbative corrections can be incorporated using recent determinations of transverse-momentum-dependent (TMD) distributions. Evolution effects for GTMDs closely follow those for TMDs and can thus be easily accounted for up to next-to-next-to-leading logarithmic accuracy. As a by-product, the relevant one-loop anomalous dimensions are derived, confirming previous results. As a practical application, numerical results for a specific kind of GTMDs are presented, highlighting some salient features.
hep-phEPJC(2022)·15 citations
03*
Sensitivity on Two-Higgs-Doublet Models from Higgs-Pair Production via $b b ˉ b b ˉ$ Final State
Kingman Cheung🇹🇼 · Yi-Lun Chung🇹🇼 · Shih-Chieh Hsu🇺🇸
Higgs boson pair production is well known to probe the structure of the electroweak symmetry breaking sector. We illustrate using the gluon-fusion process $pp \to H \to hh \to (b b ˉ) (b b ˉ)$ in the framework of two-Higgs-doublet models and how the machine learning approach (three-stream convolutional neural network) can substantially improve the signal-background discrimination and thus improves the sensitivity coverage of the relevant parameter space. We show that such $g g \to hh \to b b ˉ b b ˉ$ process can further probe the currently allowed parameter space by HiggsSignals and HiggsBounds at the HL-LHC. The results for Types I to IV are shown.
hep-phhep-exPRD(2022)·6 citations
04*
Influence of heavy resonances in SMASH
J. Salinas San Martin🇺🇸 · J. Noronha-Hostler🇺🇸 · H. Elfner🇩🇪 · J. Hammelmann🇩🇪 · R. Hirayama🇩🇪
Recent lattice QCD results, comparing to a hadron resonance gas model, have shown the need for hundreds of particles in hadronic models. These extra particles influence both the equation of state and hadronic interactions within hadron transport models. Here, we introduce the PDG21+ particle list, which contains the most up-to-date database of particles and their properties. We then convert all particles decays into 2 body decays so that they are compatible with SMASH in order to produce a more consistent description of a heavy-ion collision.
hep-phnucl-exnucl-thRev.Mex.Fis.Suppl.(2022)·5 citations
05*
A possible subthreshold pole in $S_{11}$ channel from $π N$ Roy-Steiner equation analyses
Xiong-Hui Cao🇨🇳 · Qu-Zhi Li🇨🇳 · Han-Qing Zheng🇨🇳
The hyperbolic version of Roy-Steiner equation describing low energy $π N$ scatterings, with larger analyticity domain in the complex $s$ plane is solved. The numerical results on phase shifts of low partial waves are in agreement with that of Hoferichter et al. [Phys. Rept. 625 (2016) 1]. A subthreshold pole in $S_{11}$ channel is found located at $s = (918 \pm 3) - i (163 \pm 9)$ ~MeV.
hep-phJHEP(2022)·18 citations
06*
SMEFT is falsifiable through multi-Higgs measurements (even in the absence of new light particles)
Raquel Gómez-Ambrosio🇮🇹 · Felipe J. Llanes-Estrada🇪🇸 · Alexandre Salas-Bernárdez🇪🇸 · Juan J. Sanz-Cillero🇪🇸
From the embedding of the Standard Model Effective Field Theory (SMEFT) in the more general Higgs Effective Field Theory (HEFT), we expose correlations among the coefficients of the latter that, if found to be violated in future data, would lead to the experimental falsification of the SMEFT framework. These are derived from the necessary symmetric point of HEFT and analyticity of the SMEFT Lagrangian that allows the construction of the SMEFT expansion, as laid out by other groups, and properties at that point of the Higgs-flare function $F (h)$ coupling Goldstone and Higgs bosons, of the Higgs potential $V (h)$ and of the Higgs-top quark coupling function $G (h)$ .
hep-phCommun.Theor.Phys.(2023)·40 citations
07*
Direct accessibility of the fundamental constants governing light-by-light scattering
Felix Karbstein🇩🇪 · Daniel Ullmann🇩🇪 · Elena A. Mosman🇩🇪 · Matt Zepf🇩🇪
Quantum field theory predicts the vacuum to exhibit a non-linear response to strong electromagnetic fields. This fundamental tenet has remained experimentally challenging and is yet to be tested in the laboratory. We present proof of concept and detailed theoretical analysis of an experimental setup for precision measurements of the quantum vacuum signal generated by the collision of a brilliant x-ray probe with a high-intensity pump laser. The signal features components polarised parallel and perpendicularly to the incident x-ray probe. Our proof-of-concept measurements show that the background can be efficiently suppressed by many orders of magnitude which should not only facilitate a detection of the perpendicularly polarised component of non-linear vacuum response, but even make the parallel polarised component experimentally accessible for the first time. Remarkably, the angular separation of the signal from the intense x-ray probe enables precision measurements even in presence of pump fluctuations and alignment jitter. This provides direct access to the low-energy constants governing light-by-light scattering.
hep-phquant-phPRL(2022)·41 citations
08*
Renormalisation of singlet operators to four loops
Giulio Falcioni🇬🇧
In QCD the anomalous dimensions of gauge invariant operators of twist 2 play a key role, because they control the scale dependence of the parton distribution functions. Notably, the flavour singlet operators, such as those associated to the gluon distribution, mix under renormalisation with a set of unphysical operators, also known as aliens. Missing this effect leads to wrong results already for the two-loop anomalous dimensions. The correct renormalisation of gluonic operators is an important step towards the computation of the scale evolution of flavour singlet parton distributions, which is now required to 4 loops. Leveraging both the background field method and an enhanced BRST symmetry, we construct the required ghost and alien operator basis up to 4 loops for arbitrary mass dimensions. Furthermore, we extract anomalous dimensions at 4 loops, for the physical operators of mass-dimension 4 and 6, and at 3 loops for mass-dimension 8.
hep-phPoS(2022)·2 citations
09*
Evaluation of Photos Monte Carlo ambiguities in case of four fermion final states
A. Kusina🇵🇱 · Z. Was🇵🇱
With the increasing precision requirements and growing spectrum of applications of Monte Carlo simulations the evaluation of different components of such simulations and their systematic ambiguities become of utmost interest. In the following, we will address the question of systematic errors for Photos Monte Carlo for simulation of bremsstrahlung corrections in final states, which can not, in principle, be identified as a decay of resonances. It is possible, because the program features explicit and exact parametrization of phase space for multi-body plus multi-photon final states. The Photos emission kernel for some processes consist of complete matrix element, in the remaining cases appropriate approximation is used. Comparisons with results of simulations, from generators based on exact phase space and exact fixed order matrix elements, can be used. For the purpose of such validations Photos provides an option to restrict emissions to single photon only. In the current work we concentrate on final state bremsstrahlung in $q q ˉ (e^{+} e^{-}) \to l^{+} l^{-} l^{+} l^{-} γ$ and $γ γ \to l^{+} l^{-} γ$ processes. The reference distributions used as a cross-check are obtained from the fixed-order MadGraph Monte Carlo simulations. For the purpose of validation we concentrate on those phase space regions where Photos is not expected to work on the basis of its design alone. These phase space regions of hard, non-collinear photons, do not contribute to large logarithmic terms. We find that in these phase space regions the differences between Photos and MadGraph results do not surpass a few percent and these regions, in turn, contribute about 10% to the observed process rates. This is encouraging in view of the possible ambiguities for precise calculation of realistic observables.
hep-phEPJC(2023)·1 citation
10*
Possibility of $T_{c s ˉ} (2900)$ as the resonance-like structure induced by threshold effects
Ying-Hui Ge🇨🇳 · Xiao-Hai Liu🇨🇳 · Hong-Wei Ke🇨🇳
We investigate the process $B \to D ˉ D_{s} π$ via several rescattering processes. It is shown that the triangle singularity (TS) peak around the $D^{*} K^{*}$ threshold generated from the $χ_{c 1} K^{*} D^{*}$ loop is relatively narrow, which may simulate the resonance-like structure $T_{c s ˉ} (2900)$ recently observed by LHCb in the $D_{s} π$ spectrum. However, the TS peak around the $D_{s}^{*} ρ$ threshold generated from the $D^{**} D_{s}^{*} ρ$ loop is smoothed by the broad width of $ρ$ , which itself can hardly describe the $T_{c s ˉ} (2900)$ structure. A TS signal around the $D K$ threshold generated from the $χ_{c 0} K D$ loop is also predicted.
hep-phhep-exEPJC(2022)·24 citations
11*
Analysis of the $X (3960)$ and related tetraquark molecular states via the QCD sum rules
Qi Xin🇨🇳 · Zhi-Gang Wang🇨🇳 · Xiao-Song Yang🇨🇳
In this work, we study the $D D ˉ$ , $D D$ , $D D ˉ_{s}$ , $D D_{s}$ , $D_{s} D ˉ_{s}$ and $D_{s} D_{s}$ tetraquark molecular states with the $J^{P C} = 0^{++}$ via the QCD sum rules. The prediction $M_{D_{s} D ˉ_{s}} = 3.98 \pm 0.10 GeV$ is in very good agreement with the experimental value $M_{X (3960)} = 3956 \pm 5 \pm 10 MeV$ from the LHCb collaboration and supports assigning the $X (3960)$ as the $D_{s}^{+} D_{s}^{-}$ molecular state with the $J^{P C} = 0^{++}$ . We take account of our previous works on the four-quark states consisting of two color-neutral clusters, and acquire the mass spectrum of the ground state hidden-charm and doubly-charm tetraquark molecular states.
hep-phAAPPS Bull.(2022)·42 citations
12*
Exploration of Parameter Spaces Assisted by Machine Learning
A. Hammad🇰🇷 · Myeonghun Park🇰🇷 · Raymundo Ramos🇰🇷 · Pankaj Saha🇰🇷
We demonstrate two sampling procedures assisted by machine learning models via regression and classification. The main objective is the use of a neural network to suggest points likely inside regions of interest, reducing the number of evaluations of time consuming calculations. We compare results from this approach with results from other sampling methods, namely Markov chain Monte Carlo and MultiNest, obtaining results that range from comparably similar to arguably better. In particular, we augment our classifier method with a boosting technique that rapidly increases the efficiency within a few iterations. We show results from our methods applied to a toy model and the type II 2HDM, using 3 and 7 free parameters, respectively. The code used for this paper and instructions are publicly available on the web.
hep-phcs.LGComput.Phys.Commun.(2023)·23 citations
13*
Resummation effects in the bottom-quark fragmentation function
Fabio Maltoni🇧🇪 · Giovanni Ridolfi🇮🇹 · Maria Ubiali🇬🇧 · Marco Zaro🇮🇹
We compute the perturbative component of the fragmentation function of the $b$ quark to the best of the present theoretical knowledge. The fixed-order calculation to order $α_{s}^{2}$ of the fragmentation function at the initial scale is matched with soft-emission logarithm resummation to next-to-next-to-leading logarithmic accuracy, so that order- $α_{s}^{2}$ corrections are accounted for exactly, and logarithmically enhanced contributions from loops of $b$ quarks are included. This requires the calculation of the Mellin transform of the order- $α_{s}^{2}$ result in the whole complex plane for the Mellin variable, which we provide for the first time for all the fragmenting partons. Evolution is performed to next-to-next- to-leading log accuracy, and mixing with the gluon fragmentation function is taken into account. The perturbative fragmentation functions are made available via LHAPDF grids.
hep-phJHEP(2022)·20 citations
14*
QFitter -- A Quantum Fitting Framework Applied to Effective Field Theories
Juan Carlos Criado🇬🇧 · Roman Kogler🇩🇪 · Michael Spannowsky🇬🇧
The use of experimental data to constrain the values of the Wilson coefficients of an Effective Field Theory (EFT) involves minimising a $χ^{2}$ function that may contain local minima. Classical optimisation algorithms can become trapped in these minima, preventing the determination of the global minimum. The quantum annealing framework has the potential to overcome this limitation and reliably find the global minimum of non-convex functions. We present QFitter, a quantum annealing method to perform EFT fits. Using a state-of-the-art quantum annealer, we show with concrete examples that QFitter can be used to fit sets of at least eight coefficients, including their quadratic contributions. An arbitrary number of observables can be included without changing the required number of qubits. We provide an example in which $χ^{2}$ is non-convex and show that QFitter can find the global minimum more accurately than its classical alternatives.
hep-phhep-thquant-phPRD(2023)·8 citations
15*
Higgsino Dark Matter Confronts 14 years of Fermi Gamma Ray Data
Christopher Dessert🇺🇸 · Joshua W. Foster🇺🇸 · Yujin Park🇺🇸 · Benjamin R. Safdi🇺🇸 · Weishuang Linda Xu🇺🇸
Thermal higgsino dark matter (DM), with mass around 1 TeV, is a well-motivated, minimal DM scenario that arises in supersymmetric extensions of the Standard Model. Higgsinos may naturally be the lightest superpartners in Split-supersymmetry models that decouple the scalar superpartners while keeping higgsinos and gauginos close to the TeV scale. Higgsino DM may annihilate today to give continuum gamma-ray emission at energies less than a TeV in addition to a line-like signature at energies equal to the mass. Previous searches for higgsino DM, for example with the H.E.S.S. gamma-ray telescope, have not reached the necessary sensitivity to probe the higgsino annihilation cross-section. In this work we make use of 14 years of $Fermi$ gamma-ray data at energies above $\sim$ 10 GeV to search for the continuum emission near the Galactic Center from higgsino annihilation. We interpret our results using DM profiles from Milky Way analogue galaxies in the FIRE-2 hydrodynamic cosmological simulations. We set the strongest constraints to-date on higgsino-like DM. Our results show a mild, $\sim$ 2 $σ$ preference for higgsino DM with a mass near the thermal higgsino mass and, depending on the DM density profile, the expected cross-section.
hep-phastro-ph.COPRL(2023)·38 citations
16*
Dark Matter from a Conformal Dark Sector
Sungwoo Hong🇺🇸 · Gowri Kurup🇺🇸 · Maxim Perelstein🇺🇸
We consider theories in which a dark sector is described by a Conformal Field Theory (CFT) over a broad range of energy scales. A coupling of the dark sector to the Standard Model breaks conformal invariance. While weak at high energies, the breaking grows in the infrared, and at a certain energy scale the theory enters a confined (hadronic) phase. One of the hadronic excitations can play the role of dark matter. We study a "Conformal Freeze-In" cosmological scenario, in which the dark sector is populated through its interactions with the SM at temperatures when it is conformal. In this scenario, the dark matter relic density is determined by the CFT data, such as the dimension of the CFT operator coupled to the Standard Model. We show that this simple and highly predictive model of dark matter is phenomenologically viable. The observed relic density is reproduced for a variety of SM operators ("portals") coupled to the CFT, and the resulting models are consistent with observational constraints. The mass of the COFI dark matter candidate is predicted to be in the keV-MeV range.
hep-phastro-ph.COhep-thJHEP(2023)·18 citations
17*
Renormalization of twist-two operators in QCD and its application to singlet splitting functions
Thomas Gehrmann🇨🇭 · Andreas von Manteuffel🇺🇸 · Tong-Zhi Yang🇨🇭
Splitting functions govern the scale evolution of parton distribution functions. Through a Mellin transformation, they are related to anomalous dimensions of twist-two operators in the operator product expansion. We study off-shell operator matrix element, where the physical operators mix under renormalization with other gauge-variant operators of the same quantum numbers. We devise a new method to systematically extract the Feynman rules resulting from those operators without knowing the operators themselves. As a first application of the new approach, we independently reproduce the well-known three-loop singlet splitting functions obtained from computations of on-shell quantities.
hep-phPoS(2022)·5 citations
18*
LFV Higgs and $Z$ -boson decays: leptonic CPV phases and CP asymmetries
A. Abada🇫🇷 · J. Kriewald🇫🇷 · E. Pinsard🇫🇷 · S. Rosauro-Alcaraz🇫🇷 · A. M. Teixeira🇫🇷
Heavy neutral leptons are motivated by several extensions of the Standard Model and their presence induces modifications in the lepton mixing matrix, including new Dirac and Majorana CP violating phases. It has been recently shown that these phases play an important role in lepton number and lepton flavour violating decays and transitions, with a striking impact for the predicted rates of certain observables. In this work, we now consider the potential role of the heavy neutral fermions and of the new CP violating phases in Higgs and $Z$ -boson lepton flavour violating decays $H, Z \to ℓ_{α}^{\pm} ℓ_{β}^{\mp}$ , as well as in the corresponding CP asymmetries. In order to allow for a thorough analysis, we derive the full analytical expressions of the latter observables, taking into account the effect of the (final state) charged lepton masses. A comprehensive exploration of lepton flavour violating $Z$ and Higgs decays confirms that these are very sensitive to the presence of the additional heavy neutral leptons. Moreover, the new CPV phases have a clear impact on the decay rates, leading to both destructive and constructive interferences. Interestingly, in the $μτ$ sector, the $Z \to ℓ_{α}^{\pm} ℓ_{β}^{\mp}$ rates are within reach of FCC-ee, with associated CP asymmetries that can potentially reach up to $20% - 30%$ .
hep-phhep-exEPJC(2023)·19 citations
19*
ALP Dark Matter Mini-Clusters from Kinetic Fragmentation
Cem Eröncel🇩🇪 · Géraldine Servant🇩🇪
We show that very compact axion mini-clusters can form in models where axion-like-particle (ALP) dark matter is produced via the kinetic misalignment mechanism, which is well-motivated in pre-inflationary $U (1)$ symmetry breaking scenarios. This is due to ALP fragmentation. We predict denser halos than what has been obtained so far in the literature from standard misalignment in post-inflationary $U (1)$ breaking scenarios or from large misalignment. The main reason is that adiabatic fluctuations are significant at early times; therefore, even if amplification from parametric resonance effects is moderate, the final size of ALP fluctuations is larger in kinetic misalignment. We compare halo mass functions and halo spectra obtained in kinetic misalignment, large misalignment, and standard misalignment, respectively. Our analysis does not depend on the specific model realization of the kinetic misalignment mechanism. We present our results generally as a function of the ALP mass and the ALP decay constant only. We show that a sizable region of this ALP parameter space can be tested by future experiments that probe small-scale structures.
hep-phastro-ph.COJCAP(2023)·42 citations
20*
Hard X-ray polarization catalog for a 5-year sample of Gamma-Ray Bursts using AstroSat CZT-Imager
Tanmoy Chattopadhyay · Soumya Gupta · Shabnam Iyyani · Divita Saraogi · Vidushi Sharma · Anastasia Tsvetkova · Ajay Ratheesh · Rahul Gupta🇺🇸 · N.P.S. Mithun · C. S. Vaishnava · Vipul Prasad · E. Aarthy and 7 other authors
Cadmium Zinc Telluride Imager (CZTI) aboard AstroSat has been regularly detecting Gamma-Ray Bursts (GRBs) since its launch in 2015. Its sensitivity to polarization measurements at energies above 100 keV allows CZTI to attempt spectro-polarimetric studies of GRBs. Here, we present the first catalog of GRB polarization measurements made by CZTI during its first five years of operation. This presents the time integrated polarization measurements of the prompt emission of 20 GRBs in the energy range 100-600 keV. The sample includes the bright GRBs which were detected within an angle range of 0-60 degree and 120-180 degree where the instrument has useful polarization sensitivity and is less prone to systematics. We implement a few new modifications in the analysis to enhance polarimetric sensitivity of the instrument. Majority of the GRBs in the sample are found to possess less / null polarization across the total bursts' duration in contrast to a small fraction of five GRBs exhibiting high polarization. The low polarization across the bursts can be speculated to be either due to the burst being intrinsically weakly polarized or due to varying polarization angle within the burst even when it is highly polarized. In comparison to POLAR measurements, CZTI has detected a larger number of cases with high polarization. This may be a consequence of the higher energy window of CZTI observations which results in the sampling of smaller duration of burst emissions in contrast to POLAR, thereby, probing emissions of less temporal variations of polarization properties.
↳ astro-ph.HEastro-ph.IMhep-phApJ(2022)·42 citations
21*
Neutrinos from Diffuse Supernova Background
Anna M. Suliga🇺🇸
Neutrinos are the second most abundant particles in the universe according to the Standard Model, yet they are the least likely to interact. This feature implies that detecting a neutrino can reveal valuable insights into its source. Among the known sources of neutrinos, core-collapse supernovae are one of the most efficient factories. On average, a single collapse occurs every second in the observable universe, emitting approximately $1 0^{58}$ neutrinos. The total flux of neutrinos reaching Earth from all core-collapse supernovae across the universe is the diffuse supernova neutrino background (DSNB). Detection of the DSNB is just around the corner. This guaranteed flux of astrophysical neutrinos encodes information about the whole supernova population, including an answer to a currently unsolved question about the rate at which black holes form from massive stars. This chapter discusses the ingredients entering the DSNB calculation as well as current experimental limits and hints.
↳ astro-ph.HEhep-phHandbook of Nuclear Physics, Springer, Si…·20 citations
22*
Ultracompact hybrid stars consistent with multimessenger astrophysics
Jia Jie Li (SWU, Chongqing)🇨🇳 · Armen Sedrakian (FIAS, Frankfurt and U. Wroclaw)🇩🇪 · Mark Alford (Washington U., St. Louis)🇺🇸
In this work, we consider the consequences of phase transition in dense QCD on the properties of compact stars and implications for the observational program in gravitational wave and X-ray astrophysics. The key underlying assumption of our modeling is a strong first-order phase transition past the point where the hadronic branch of compact stars reaches the two-solar mass limit. Our analysis predicts ultracompact stars with very small radii - in the range of 6-9 km - living on compact star sequences that are entirely consistent with the current multimessenger data. We show that sequences featuring two-solar mass hadronic stars consistent with radio-pulsar observations are also consistent with the inferences of large radii for massive neutron stars by NICER X-ray observations of neutron stars and the small radii predicted by gravitational waves analysis of the binary neutron star inspiral event GW170817 for our models that feature a strong first-order QCD phase transition.
↳ astro-ph.HEhep-phPRD(2023)·32 citations
23*
The Asymptotically Safe Standard Model: From quantum gravity to dynamical chiral symmetry breaking
Álvaro Pastor-Gutiérrez🇩🇪 · Jan M. Pawlowski🇩🇪 · Manuel Reichert🇬🇧
We present a comprehensive non-perturbative study of the phase structure of the asymptotically safe Standard Model. The physics scales included range from the asymptotically safe trans-Planckian regime in the ultraviolet, the intermediate high-energy regime with electroweak symmetry breaking to strongly correlated QCD in the infrared. All flows are computed with a self-consistent functional renormalisation group approach, using a vertex expansion in the fluctuation fields. In particular, this approach takes care of all physical threshold effects and the respective decoupling of ultraviolet degrees of freedom. Standard Model and gravity couplings and masses are fixed by their experimental low energy values. Importantly, we accommodate for the difference between the top pole mass and its Euclidean analogue. Both, the correct mass determination and the threshold effects have a significant impact on the qualitative properties, and in particular on the stability properties of the specific ultraviolet-infrared trajectory with experimental Standard Model physics in the infrared. We show that in the present rather advanced approximation the matter part of the asymptotically safe Standard Model has the same number of relevant parameters as the Standard Model, and is asymptotically free. This result is based on the novel UV fixed point found in the present work: the fixed point Higgs potential is flat but has two relevant directions. These results and their analysis are accompanied by a thorough discussion of the systematic error of the present truncation, also important for systematic improvements.
↳ hep-thgr-qchep-phSciPost Phys.(2023)·63 citations
24*
Dark Matter as an effect of a minimal length
Pasquale Bosso🇨🇦 · Mitja Fridman🇨🇦 · Giuseppe Gaetano Luciano🇮🇹
In this work, we consider the implications of a phenomenological model of quantum gravitational effects related to a minimal length, implemented via the Generalized Uncertainty Principle. Such effects are applied to the Bekenstein-Hawking entropy to derive a modified law of gravity through Verlinde's conjecture. Implications on galactic scales, and in particular on the shape of rotational curves, are investigated, exploring the possibility to mimic dark matter-like effects via a minimal length.
↳ gr-qchep-phFront.Astron.Space Sci.(2022)·7 citations
25*
Primordial black holes from an inflationary potential valley
Bao-Min Gu🇨🇳 · Fu-Wen Shu🇨🇳 · Ke Yang🇨🇳 · Yu-Peng Zhang🇨🇳
Primordial black holes (PBHs) could be formed if large perturbations are generated on small scales in inflation. We study a toy inflation model with a local minimum. The curvature perturbations are enhanced when the inflaton passes through the local minimum, with more efficient amplification rate than that of quasi-inflection point inflation, leading to the production of PBHs on small scales. The PBHs could comprise the total dark matter in the mass window $1 0^{16}$ -- $1 0^{20}$ g.
↳ astro-ph.COgr-qchep-phhep-thPRD(2023)·29 citations
26*
Improved renormalization scheme for nonlocal operators
Martha Constantinou🇺🇸 · Haralambos Panagopoulos🇨🇾
In this paper we present an improved RI-type prescription appropriate for the non-perturbative renormalization of gauge invariant nonlocal operators. In this prescription, the non-perturbative vertex function is improved by subtracting unwanted finite lattice spacing ( $a$ ) effects, calculated in lattice perturbation theory. The method is versatile and can be applied to a wide range of fermion and gluon actions, as well as types of nonlocal operators. The presence of operator mixing can also be accommodated. Compared to the standard RI' prescription, this variant can be recast as a supplementary finite renormalization, whose coefficients bring about corrections of higher order in $a$ ; consequently, it coincides with standard RI' as $a \to 0$ , however it can afford us a smoother and more controlled extrapolation to the continuum limit. In this proof-of-concept calculation we focus on nonlocal fermion bilinear operators containing a straight Wilson line. In the numerical implementation we use Wilson/clover fermions and Iwasaki improved gluons. The finite- $a$ terms were calculated to one-loop level in lattice perturbation theory, and to all orders in $a$ , using the same action as the non-perturbative vertex functions. We find that the method leads to significant improvement in the perturbative region indicated by small and intermediate values of the length of the Wilson line. This results in a robust extraction of the renormalization functions in that region. We have also applied the above method to operators with stout-smeared links. We show how to perform the perturbative correction for any number of smearing iterations, and evaluate its effect on the power divergent renormalization coefficients.
↳ hep-lathep-phhep-thPRD(2023)·13 citations
27*
Search for a New B-L Z' Gauge Boson with the NA64 Experiment at CERN
Yu. M. Andreev🇷🇺 · D. Banerjee🇨🇭 · B. Banto-Oberhauser🇨🇭 · J. Bernhard🇨🇭 · P. Bisio🇮🇹 · M. Bondi🇮🇹 · V. Burtsev🇷🇺 · A. Celentano🇮🇹 · N. Charitonidis🇨🇭 · A. G. Chumakov🇷🇺 · D. Cooke🇬🇧 · P. Crivelli🇨🇭 and 46 other authors
A search for a new $Z^{'}$ gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22e11 electrons on target collected during 2016-2021 runs no signal events were found. This allows to derive new constraints on the $Z^{'} - e$ coupling strength, which for the mass range $0.3 < m_{Z^{'}} < 100$ MeV are more stringent compared to those obtained from the neutrino-electron scattering data.
↳ hep-exhep-phPRL(2022)·50 citations
28*
Primordial black hole dark matter from inflation: the reverse engineering approach
Gabriele Franciolini🇮🇹 · Alfredo Urbano🇮🇹
Constraining the inflationary epoch is one of the aims of modern cosmology. In order to fully exploit current and future small-scale observations, it is necessary to devise tools to directly relate them to the early universes dynamics. We present here a novel reverse engineer approach able to connect fundamental late-time observables to consistent inflationary dynamics and, eventually, to the inflaton potential. Employing this procedure, we are able to describe which conditions can give rise to a raised plateau in the power spectrum of curvature perturbations at small scales, which are not constrained by CMB observations. Within this new phenomenologically-driven approach, we find that inflation can generate a raised plateau in the spectrum of curvature perturbations that potentially connects three fundamental observables: a dominant component of the dark matter in the form of asteroid-mass/atomic-size primordial black holes; detectable signals in stochastic gravitational waves and a subdominant fraction of stellar-mass primordial black holes mergers.
↳ astro-ph.COgr-qchep-phPRD(2022)·61 citations
29*
Functional flows for complex effective actions
Friederike Ihssen🇩🇪 · Jan M. Pawlowski🇩🇪
In the present work we set up a general functional renormalisation group framework for the computation of complex effective actions. For explicit computations we consider both flows of the Wilsonian effective action and the one-particle irreducible (1PI) effective action. The latter is based on an appropriate definition of a Legendre transform for complex actions, and we show its validity by comparison to exact results in zero dimensions, as well as a comparison to results for the Wilsonian effective action. In the present implementations of the general approaches, the flow of the Wilsonian effective action has a wider range of applicability and we obtain results for the effective potential of complex fields in $ϕ^{4}$ -theories from zero up to four dimensions. These results are also compared with results from the 1PI effective action within its range of applicability. The complex effective action also allows us to determine the location of the Lee-Yang zeros for general parameter values. We also discuss the extension of the present results to general theories including QCD.
↳ hep-thhep-lathep-phSciPost Phys.(2023)·28 citations
30*
Examining Temporal Variation of the Fermi Coupling Constant using SNe Ia Light Curves
Akshay Rana · Vedanta Thapar · Hari Prasad S.V. · Sandra Elsa Sanjai
In standard model, the Fermi coupling constant, $G_{F}$ , sets the strength of electroweak decay. We attempt an approach to constrain the temporal variation of the Fermi coupling constant $G_{F}$ . To probe it, Type Ia supernovae (SNe Ia) light curves are being used as a source of reliable primordial nucleosynthesis events across the redshifts. We utilized studies suggesting that in the initial phase after the SNe Ia explosion, the electroweak decay of $^{56} N i \to^{56} C o \to^{56} F e$ is the key contributor to powering the SNe Ia light curve. We hence used the Pan-STARRS supernovae catalog having 1169 supernovae light curves in $g$ , $r$ , $i$ , and $z$ spectral filters. The post-peak decrease in the apparent magnitude of light curves (in the rest frame of SNe) was related to the electroweak decay rate of primordial nucleosynthesis. Further, the decay rate relates to $G_{F}$ . To keep the analysis independent of the cosmological model, we used the Hubble parameter measurement and a non-parametric statistical method, the Gaussian Process. Our study suggests a small yet finite temporal variation of $G_{F}$ and puts a strong upper bound on the present value of the fractional change in the Fermi coupling constant i.e; $\frac{G ˙ _{F}}{G _{F}}_{z = 0} \approx 1 0^{- 11} y r^{- 1}$ using datasets spread over a redshift range $0 < z < 0.75$ .
↳ astro-ph.COastro-ph.HEhep-exhep-ph+10 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.