HEP Phenomenology·hep-ph
44 papers—29 primary·15 cross-listed·reconstructed*
We discuss possibilities to test physics beyond the Standard Model in semileptonic, hadronic and missing energy decay modes. Clean null test observables such as angular observables, CP-asymmetries and lepton universality tests are presented and model-independent correlations as well as details within flavorful, anomaly-free models are worked out.
Megan H. McDuffie🇺🇸 · Ephraim Fischbach🇺🇸 · Dennis E. Krause🇺🇸 · John T. Gruenwald🇺🇸 · Michael J. Mueterthies🇺🇸 · Carol Y. Scarlett🇺🇸 · Belvin Freeman🇺🇸
We have reanalyzed data obtained by Potter in a 1923 experiment aimed at testing whether the accelerations of test masses in the Earth's gravitational field are independent of their compositions. Although Potter concludes that the accelerations of his samples compared to a brass standard were individually consistent with a null result, we show that the pattern formed from a combined plot of all of his data suggests the presence of a fifth force coupling to baryon number.
Naoyuki Haba🇯🇵 · Nobuchika Okada🇺🇸 · Toshifumi Yamada🇯🇵
Low-energy data, combined with renormalization group (RG) equations, can predict new physics at far higher energy scales. In this paper, we consider the possibility that the measured Higgs boson mass and top quark mass hint at a five-dimensional gauge-Higgs unification (5D GHU) model at a scale above TeV. We note that the vanishing of the Higgs quartic coupling and the proximity of the top quark Yukawa coupling and weak gauge coupling at high scales, inferred from the experimental data, are in harmony with 5D GHU, because in 5D GHU models the Higgs quartic coupling is forbidden by the 5D gauge symmetry and the Yukawa couplings and the weak gauge coupling originate from a common 5D gauge coupling. Based on the above insight, we propose a 5D GHU model where the Standard Model fermions are embedded in 5D fermions in a way to tightly relate the top Yukawa coupling with the weak gauge coupling. Also, the model predicts the presence of vector-like fermions (other than the Kaluza-Klein modes), which can affect the RG evolutions of the 4D theory and reconcile the scale of vanishing Higgs quartic coupling and that of equality of the top Yukawa and weak gauge couplings, thereby achieving a successful matching of the 4D theory with 5D GHU. We predict the vector-like fermion mass and the compactification scale of 5D GHU from the conditions for the successful matching.
Ya Li🇨🇳 · Da-Cheng Yan🇨🇳 · Jun Hua🇨🇳 · Zhou Rui🇨🇳 · Hsiang-nan Li🇹🇼
We perform a global analysis of three-body charmless hadronic decays in the perturbative QCD (PQCD) approach, where denotes an intermediate vector resonance, and , , denote final-state pseudoscalar mesons. Fitting the PQCD factorization formulas at leading order in the strong coupling to measured branching ratios and direct asymmetries, we determine the Gegenbauer moments in the two-meson distribution amplitudes (DAs) for the meson pairs . The fitted Gegenbauer moments are then employed to make predictions for those observables, whose data are excluded in the fit due to larger experimental uncertainties. A general consistency between our predictions and data is achieved, which hints the validity of the PQCD formalism for the above three-body meson decays and the universality of the nonperturbative two-meson DAs. The obtained two-meson DAs can be applied to PQCD studies of other multi-body meson decays involving the same meson pairs. We also attempt to determine the dependence of the Gegenbauer moments on the meson-pair invariant mass, and demonstrate that this determination is promising, when data become more precise.
Zhan Bai🇨🇳 · Yu-xin Liu🇨🇳
We study the phase structure and phase transition of cold dense QCD matter via the Dyson-Schwinger equation approach. We take the rainbow approximation and the Gaussian-type gluon model. In order to guarantee that the quark number density begins to appear at the nuclear liquid-gas phase transition chemical potential, we propose a chemical potential dependent modification factor for the gluon model. We find that for the iso-symmetric quark matter, the modification reduces the chemical potential of the phase coexistence region of the first--order phase transition. We also implement the relativistic mean field theory to describe the hadron matter, and make use of the Maxwell and Gibbs construction method to study the phase transition of beta--equilibrium and charge neutral matter in compact stars. The results show that the phase transition will not happen in case of the Gaussian--type gluon model without any modification. The results also indicate that the upper boundary of the coexistence region should be larger than the current Nambu solution existing region. We also calculate the mass-radius relation of the compact stars, and find that the hadron-quark phase transition happens at too high chemical potential so that the maximum mass of the compact star is hardly affected by the hadron-quark phase transition.
Xiangdong Ji🇺🇸 · Yizhuang Liu🇵🇱 · Andreas Schäfer🇩🇪
We study the anomalous scale symmetry breaking effects on the proton mass in QCD due to quantum fluctuations at ultraviolet scales. We confirm that a novel contribution naturally arises as a part of the proton mass, which we call the quantum anomalous energy (QAE). We discuss the QAE origins in both lattice and dimensional regularizations and demonstrate its role as a scheme-and-scale independent component in the mass decomposition. We further argue that QAE role in the proton mass resembles a dynamical Higgs mechanism, in which the anomalous scale symmetry breaking field generates mass scales through its vacuum condensate, as well as its static and dynamical responses to the valence quarks. We demonstrate some of our points in two simpler but closely related quantum field theories, namely the 1+1 dimensional non-linear sigma model in which QAE is non-perturbative and scheme-independent, and QED where the anomalous energy effect is perturbative calculable.
O. M. Ozsimsek (1)🇹🇷 · V. Ari (2)🇹🇷 · O. Cakir (2) ((1) Hacettepe University, (2) Ankara University)🇹🇷
We investigate the potential of the HL-LHC for discovering new physics effects via the same-sign top pair signatures. We focus on the semi leptonic (electron and muon) decay of the top quarks and study the reach for a simplified model approach where top quark flavor changing could occur through a neutral scalar exchange. A relatively smaller background contribution and clean signature are the advantages of the leptonic decay mode of the same-sign bosons in the same-sign production processes of top quark pairs. Assuming the FCNC between top quark, up type quark and scalar boson from the new physics interactions the branchings could be excluded of the order . We use angular observables of the same-sign lepton pairs and the top quark kinematics in the process which provide the possibility of separation of new physics signal from the SM backgrounds using machine learning teqniques. We find that the same-sign top quark pair production is quite capable of testing the top-Higgs FCNCs at the HL-LHC.
Charanjit K. Khosa (1)🇮🇹 · Simone Marzani (1) ((1) Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova)🇮🇹
We construct a procedure to separate boosted Higgs bosons decaying into hadrons, from the background due to strong interactions. We employ the Lund jet plane to obtain a theoretically well-motivated representation of the jets of interest and we use the resulting images as the input to a convolutional neural network classifier. In particular, we consider two different decay modes of the Higgs boson, namely into a pair of bottom quarks or into light jets, against the respective backgrounds. For each case, we consider both a moderate- and high- boost scenario. The performance of the tagger is compared to what is achieved using a traditional single-variable analysis which exploits a QCD inspired color-singlet tagger, namely the jet color ring observable.
Reza Ebadi🇺🇸 · Anubhav Mathur🇺🇸 · Erwin H. Tanin🇺🇸 · Nicholas D. Tailby🇺🇸 · Mason C. Marshall🇺🇸 · Aakash Ravi🇺🇸 · Raisa Trubko🇺🇸 · Roger R. Fu🇺🇸 · David F. Phillips🇺🇸 · Surjeet Rajendran🇺🇸 · Ronald L. Walsworth🇺🇸
Self-interactions within the dark sector could clump dark matter into heavy composite states with low number density, leading to a highly suppressed event rate in existing direct detection experiments. However, the large interaction cross section between such ultra-heavy dark matter (UHDM) and standard model matter results in a distinctive and compelling signature: long, straight damage tracks as they pass through and scatter with matter. In this work, we propose using geologically old quartz samples as large-exposure detectors for UHDM. We describe a high-resolution readout method based on electron microscopy, characterize the most favorable geological samples for this approach, and study its reach in a simple model of the dark sector. The advantage of this search strategy is two-fold: the age of geological quartz compensates for the low number density of UHDMs, and the distinct geometry of the damage track serves as a high-fidelity background rejection tool.
P. Pakhlov🇷🇺 · T. Uglov🇷🇺
A measurement of the photon polarization in radiative penguin decays provides a test of the Standard Model and a probe for New Physics, that can lead to a deviation from the Standard Model prediction of left-handed photons in . We propose a new method to measure the photon polarization using the baryonic decay . The -violating -hyperon decay allows a measurement of the helicity to be performed, which can be uniquely related to the photon polarization in a model-independent way. The decay was recently measured to have a large branching fraction providing a possibility to get meaningful results with the data already available at LHC and B-factory experiments. An increase of the -meson sample at high luminosity LHC experiments and Belle II should provide a really stringent test by using this method already in the near future.
Bastián Díaz Sáez🇩🇪 · Patricio Escalona🇨🇱 · Sebastián Norero🇨🇱 · Alfonso R. Zerwekh🇨🇱
We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the parameter space, and the model is sensitive to indirect searches.
The dark sector, composed of the fields neutral under the Standard Model (SM) gauge group, can couple to the SM through the Higgs, hypercharge and neutrino portals, and pull the SM towards its scale by loop corrections. This instability, not possible to prevent in the known SM completions like supersymmetry due to their sizable couplings to the SM, calls for alternative mechanisms which can neutralize sensitivities of the SM to the dark sector scale and to the ultraviolet cutoff above it. Here we review such a mechanism in which incorporation of gravity into the SM predicts the existence of a dark sector and allows it to be naturally-coupled to the SM. We discuss and illustrate salient processes which can probe the naturally-coupled dark sectors.
S. El Asri🇲🇦 · S. Mouslih🇲🇦 · M. Jakha🇲🇦 · B. Manaut🇲🇦 · Y. Attaourti🇲🇦 · S. Taj🇲🇦 · R. Benbrik🇲🇦
In view of the great contribution of neutrino-electron scattering to the deep understanding of electroweak interactions, we focus in this paper on the study of elastic scattering of a muon neutrino by an electron in the presence of a circularly polarized electromagnetic field. We perform our theoretical calculation within the framework of Fermi theory using the exact wave functions of charged particles in an electromagnetic field. The expression of the differential cross section (DCS) for this process is obtained analytically in the absence and presence of the laser field. The effect of the field strength and frequency on the exchange of photons as well as on the DCS is presented and analyzed. Massive neutrino effects are also included and discussed. This study, added to the previous ones, will significantly enrich our knowledge in fundamental physics.
Apriadi Salim Adam🇮🇩 · Nicholas J.Benoit · Yuta Kawamura🇯🇵 · Yamato Matsuo · Takuya Morozumi🇯🇵 · Yusuke Shimizu🇯🇵 · Yuya Tokunaga🇯🇵 · Naoya Toyota🇯🇵
In this talk, we have reviewed the recent development on the time evolution of lepton family number carried by Majorana neutrinos \cite{Adam:2021qiq}. This article focuses on the subtle points of the derivation of the lepton family numbers and their time evolution. We also show how the time evolution is sensitive to and components of the effective Majorana mass matrix by applying the formula to the two family case. The dependence on the Majorana phase is clarified and the implication on CNB (cosmic neutrino background) is also discussed.
We discuss the prospects of diffractive dijet photoproduction at the EIC to distinguish different fits of diffractive proton PDFs, different schemes of factorization breaking, to determine diffractive nuclear PDFs and pion PDFs from leading neutron production.
Let's be frank: we all love WIMP dark matter (DM). However, thermal equilibrium may not be reached between the visible and dark sectors. The only interaction guaranteed between them is gravity. Gravitational DM could be generated by the Hawking evaporation of primordial black holes. It is typically assumed that after production, DM abundance freezes and remains constant. However, thermalization and number-changing processes in the dark sector can have a strong impact, in particular enhancing the DM population by several orders of magnitude. Here we review the impact of self-interactions from general arguments such as the conservation of energy and entropy, independently from the underlying particle physics details of the dark sector. Additionally, we study the interplay with other purely gravitational DM production mechanisms, such as the scattering of standard model states or inflatons, mediated by the -channel exchange of gravitons. We show that the latter mechanism sets strong bounds, excluding large regions of the parameter space favored by primordial black hole production.
Shinsuke Kawai🇰🇷 · Jinsu Kim🇨🇭
In the gravitational effective theories including higher curvature terms, cosmological solutions can have nontrivial de Sitter fixed points. We study phenomenological implications of such points, focusing on a theory in which a massive scalar field is nonminimally coupled to the Euler density. We first analyze the phase portrait of the dynamical system and show that the fixed point can be a sink or a saddle, depending on the strength of the coupling. Then, we compute the perturbation spectra generated in the vicinity of the fixed point in order to investigate whether the fixed point may be considered as cosmic inflation. We find parameter regions that are consistent with the cosmological data, given that the anisotropies in the cosmic microwave background are seeded by the fluctuations generated near the fixed point. Future observation may be used to further constrain the coupling function of this model. We also comment briefly on the swampland conjecture.
R. Bruschini🇪🇸 · P. González🇪🇸
We apply the diabatic approach, specially suited for a QCD based study of conventional (quark-antiquark) and unconventional (quark-antiquark + meson-meson) meson states, to the description of hidden-bottom mesons. A spectral analysis of the , and resonances with masses up to about GeV is carried out. Masses and widths of all the experimentally known resonances, including conventional and unconventional states, can be well reproduced. In particular, we predict a significant component in . We also predict the existence of a not yet discovered unconventional narrow state, with a significant content making it to decay into , whose experimental discovery would provide definite support to our theoretical analysis.
Y. Zhou🇺🇸 · C. Cocuzza🇺🇸 · F. Delcarro🇺🇸 · W. Melnitchouk🇺🇸 · A. Metz🇺🇸 · N. Sato🇺🇸
We present a comprehensive impact study of future Electron-Ion Collider (EIC) data for parity-conserving and parity-violating polarization asymmetries on quark and gluon helicity distributions in the proton. The study, which is based on the JAM Monte Carlo global QCD analysis framework, explores the role of the extrapolation uncertainty and SU(3) flavor symmetry constraints in the simulated double-spin asymmetry, , at small parton momentum fractions and its effect on the extracted parton polarizations. We find that different assumptions about extrapolations and SU(3) symmetry can have significant consequences for the integrated quark and gluon polarizations, for polarized proton, deuteron and He beams. For the parity-violating asymmetry, , we study the potential impact on the polarized strange quark distribution with different extrapolations of , finding the constraining power to be ultimately limited by the EIC machine luminosity.
M. Czakon🇩🇪 · R.V. Harlander🇩🇪 · J. Klappert🇩🇪 · M. Niggetiedt🇩🇪
The impact of the finite top-quark mass on the inclusive Higgs production cross section at higher perturbative orders has been an open question for almost three decades. In this paper, we report on the computation of this effect at NNLO QCD. For the purely gluonic channel, it amounts to relative to the result obtained in the HEFT approximation. The formally sub-leading partonic channels over-compensate this shift, leading to an overall effect of at a collider energy of , and at . This result eliminates one of the main theoretical uncertainties to inclusive Higgs production cross section at the LHC.
The impact of recent results on Big Bang Nucleosynthesis is assessed. These include the Planck likelihood distributions for the baryon density; recent progress in helium abundance determinations; and a recent cross section measurement for d(p,\gamma)3He.
Qing-Hong Cao🇨🇳 · Hao-ran Jiang🇨🇳 · Guojin Zeng🇨🇳
One way to probe new physics beyond standard model is to check the correlation among higher dimension operators in effective field theory. We examine the strong correlation between the processes of and which both depend on the same three operators. The correlation indicates that, according to the data of , which is far below the current upper limit .
Following a previous proposal, lepton number is considered as the result of a spontaneously broken non-Abelian gauge symmetry. New fermions are added to support this new symmetry, the spontaneous breaking of which allows these new fermions to be part of the dark sector, together with the vector gauge boson which communicates between them and the usual leptons. A byproduct is a potential significant contribution to the muon anomalous magnetic moment.
Bin Yan🇺🇸
Probing Higgs width is critical to test the Higgs properties. In this work we propose to measure at the collider with a model-independent analysis under the Standard Model Effective Field Theory framework. We demonstrate that making use of the cross section measurements from , production and Higgs decay branching ratios , one could determine at a percentage level with a center of mass energy and 350 GeV and integrated luminosity . This conclusion would not depend on the assumption of the fermion Yukawa interactions. We further apply this result to constrain the fermion Yukawa couplings and it shows that the couplings could be well constrained.
Martin Hoferichter🇨🇭 · Bai-Long Hoid🇨🇭 · Bastian Kubis🇩🇪 · Jan Lüdtke🇦🇹
We present an improved Standard-Model (SM) prediction for the dilepton decay of the neutral pion. The loop amplitude is determined by the pion transition form factor for , for which we employ a dispersive representation that incorporates both space-like and time-like data as well as short-distance constraints. The resulting SM branching fraction, , sharpens constraints on physics beyond the SM, including pseudoscalar and axial-vector mediators.
Andrea Caputo🇮🇱 · Alexander J. Millar🇸🇪 · Ciaran A. J. O'Hare🇦🇺 · Edoardo Vitagliano🇺🇸
The dark photon is a massive hypothetical particle that interacts with the Standard Model by kinetically mixing with the visible photon. For small values of the mixing parameter, dark photons can evade cosmological bounds to be a viable dark matter candidate. Due to the similarities with the electromagnetic signals generated by axions, several bounds on dark photon signals are simply reinterpretations of historical bounds set by axion haloscopes. However, the dark photon has a property that the axion does not: an intrinsic polarisation. Due to the rotation of the Earth, accurately accounting for this polarisation is nontrivial, highly experiment-dependent, and depends upon assumptions about the dark photon's production mechanism. We show that if one does account for the DP polarisation, and the rotation of the Earth, an experiment's discovery reach can be enhanced by over an order of magnitude. We detail the strategies that would need to be taken to properly optimise a dark photon search. These include judiciously choosing the location and orientation of the experiment, as well as strategically timing any repeated measurements. Experiments located at 35 or 55 latitude, making three observations at different times of the sidereal day, can achieve a sensitivity that is fully optimised and insensitive to the dark photon's polarisation state, and hence its production mechanism. We also point out that several well-known searches for axions employ techniques for testing signals that preclude their ability to set exclusion limits on dark photons, and hence should not be reinterpreted as such.
Yifan Chen🇨🇳 · Yuxin Liu🇨🇳 · Ru-Sen Lu🇨🇳 · Yosuke Mizuno🇨🇳 · Jing Shu🇨🇳 · Xiao Xue🇨🇳 · Qiang Yuan🇨🇳 · Yue Zhao🇺🇸
The hitherto unprecedented angular resolution of the Event Horizon Telescope (EHT) has created exciting opportunities in the search for new physics. Recently, the linear polarization of radiation emitted near the supermassive black hole M87 was measured on four separate days, precisely enabling tests of the existence of a dense axion cloud produced by a spinning black hole. The presence of an axion cloud leads to a frequency-independent oscillation in the electric vector position angle (EVPA) of this linear polarization. For a nearly face-on M87, this oscillation in the EVPA appears as a propagating wave along the photon ring. In this paper, we leverage the azimuthal distribution of EVPA measured by the EHT to study the axion-photon coupling. We propose a novel differential analysis procedure to reduce the astrophysical background, and derive stringent constraints on the existence of axions in the previously unexplored mass window ~eV.
Jakub Filipek🇺🇸 · Shih-Chieh Hsu🇺🇸 · John Kruper🇺🇸 · Kirtimaan Mohan🇺🇸 · Benjamin Nachman🇺🇸
With the great promise of deep learning, discoveries of new particles at the Large Hadron Collider (LHC) may be imminent. Following the discovery of a new Beyond the Standard model particle in an all-hadronic channel, deep learning can also be used to identify its quantum numbers. Convolutional neural networks (CNNs) using jet-images can significantly improve upon existing techniques to identify the quantum chromodynamic (QCD) (`color') as well as the spin of a two-prong resonance using its substructure. Additionally, jet-images are useful in determining what information in the jet radiation pattern is useful for classification, which could inspire future taggers. These techniques improve the categorization of new particles and are an important addition to the growing jet substructure toolkit, for searches and measurements at the LHC now and in the future.
Bakul Agarwal🇺🇸 · Federico Buccioni🇬🇧 · Andreas von Manteuffel🇺🇸 · Lorenzo Tancredi🇬🇧
We present the complete two-loop corrections in massless QCD for the production of two photons and a jet, taking into account all color structures. In particular, we analytically compute all two-loop helicity amplitudes for the quark-antiquark, quark-gluon, and antiquark-gluon channel, and check them with an independent calculation of the polarization-summed interference with the tree amplitude. This is the first time that two-loop QCD corrections to a five-point scattering process have been computed beyond the leading-color approximation for all helicity configurations.
Ricardo Perez-Martinez🇲🇽 · Saul Ramos-Sanchez🇲🇽 · Patrick K.S. Vaudrevange🇩🇪
Leptoquarks extending the Standard Model (SM) are attracting an increasing attention in the recent literature. Hence, the identification of 4D SM-like models and the classification of allowed leptoquarks from strings is an important step in the study of string phenomenology. We perform the most extensive search for SM-like models from the non-supersymmetric heterotic string , resulting in more than 170,000 inequivalent promising string models from 138 Abelian toroidal orbifolds. We explore the 4D massless particle spectra of these models in order to identify all exotics beside the three generations of quarks and leptons. Hereby, we learn which leptoquark can be realized in this string setup. Moreover, we analyze the number of SM Higgs doublets which is generically larger than one. Then, we identify SM-like models with a minimal particle content. These so-called "almost SM" models appear most frequently in the orbifold geometries (2,4) and (1,6). Finally, we apply machine learning to our dataset in order to predict the orbifold geometry where a given particle spectrum can be found most likely.
Ignatios Antoniadis🇫🇷 · Karim Benakli🇫🇷 · Wenqi Ke🇫🇷
Gravitinos can inherit a non-relativistic dispersion relation while propagating in a background breaking both supersymmetry and Lorentz symmetry spontaneously. This is because the longitudinal mode velocity is controlled by the sound speed in the background. It was pointed out recently by Kolb, Long and McDonough that the production of gravitinos might diverge when this sound speed vanishes. We argue that in the framework of cosmological models with linearly spontaneously broken realised supersymmetry, where the physical fermions are combinations of the vacuum goldstino and the inflatino, the gravitino longitudinal mode has a relativistic dispersion relation and therefore avoids the catastrophic production. We illustrate this in some explicit examples.
A mirror-extended standard model (MESM) is offered, where in the left-right symmetric underlying action the sector of the standard model (SM) and its mirror copy have the same SU(2)\times U(1) gauge structure and parameters; the mirror fermion counter-partners have opposite chiralities. A theory is used that allows one to obtain MESM in Minkowski space only if we start with an accurate account of gravity and only at the end go to the limit of Minkowski space. Spontaneous breaking of left-right symmetry and the "wrong" sign in the mass terms of the Higgs fields potentials arise due to the initial conditions imposed on the T-model inflation. MESM allows choosing the universal Yukawa coupling constant in the underlying Lagrangian for all generations of charged leptons and up-quarks. As an example, with y=10^{-3}, it is shown that a set of additional dimensionless parameters in width range less than 0.5 is sufficient to obtain the masses of all known charged leptons and up-quarks. In this sense, MESM bypasses the problem of the fermion mass hierarchy. With this choice of parameters, MESM predicts that vacuum expectation value for the mirror Higgs field is 10^{14}GeV and masses of mirror particles are in the range 10^{8}GeV-10^{14}GeV. There is only gravitational interaction between particles of the SM and mirror sectors. Hence, mirror particles can constitute dark matter. The vacuum is realized as a limiting state in the cosmological evolution of the inflaton and classical Higgs fields, in which the energy stored in them becomes minimal, providing the maximum possible contribution of these fields to the entropy of the Universe. If further study of the model reveals the existence of an effective mechanism for preheating the Universe, this will mean that the cosmological constant problem is absent.
Stefano Bolognesi🇮🇹 · Kenichi Konishi🇮🇹 · Andrea Luzio🇮🇹
We present a simple argument which seems to favor, when applied to a large class of strongly-coupled chiral gauge theories, a dynamical-Higgs-phase scenario, characterized by certain bifermion condensates. Flavor symmetric confining vacua described in the infrared by a set of baryonlike massless composite fermions saturating the conventional 't Hooft anomaly matching equations, appear instead disfavored. Our basic criterion is that it should be possible to write a strong-anomaly effective action, analogous to the one used in QCD to describe the solution of the problem in the low-energy effective action, by using the low-energy degrees of freedom in the hypothesized infrared theory. We also comment on some well-known ideas such as the complementarity and the large planar dominance in the context of these chiral gauge theories.Some striking analogies and contrasts between the massless QCD and chiral gauge theories seem to emerge from this discussion.
We present algorithmic perturbative solution of SYM quantum spectral curve in the case of twist 2 operators, valid to in principle arbitrary order in coupling constant. The latter treats operator spins as arbitrary integer values and is written in terms of special class of functions -- products of rational functions in spectral parameter with sums of Baxter polynomials and Hurwitz functions. It is shown that this class of functions is closed under elementary operations, such as shifts, partial fractions, multiplication by spectral parameter and differentiation. Also, it is fully sufficient to solve arising non-homogeneous multiloop Baxter and first order difference equations. As an application of the proposed method we present the computation of anomalous dimensions of twist 2 operators up to four loop order.
Future linear colliders aim for extremely high precision measurements. To achieve this, not only excellent detectors and well controlled machine conditions are needed, but also the best possible estimate of backgrounds. To avoid that lacking channels and too low statistics becomes a major source of systematic errors in data-MC comparisons, all SM channels with the potential to yield at least a few events under the full lifetime of the projects need to be generated, with statistics largely exceeding that of the real data. Also machine conditions need to be accurately taken into account. This includes beam-polarisation, interactions due to the photons inevitably present in the highly focused beams, and coherent interactions of whole bunches. This endeavour has already been partly achieved in preparing design documents for both the ILC and CLIC: Comprehensive samples of fully simulated and reconstructed events are available for use. In this contribution, we present how the generation of physics events at linear colliders is categorised and organised, and the tools used. Also covered is how different aspects of machine conditions, different sources of spurious interactions (such as beam-induced backgrounds) are treated and the tools involved for these aspects.
F. Abudinén · I. Adachi · R. Adak · K. Adamczyk · P. Ahlburg · J. K. Ahn · H. Aihara · N. Akopov · A. Aloisio · F. Ameli · L. Andricek · N. Anh Ky and 540 other authors
We report measurements of branching fractions () and direct -violating asymmetries () for the decays and reconstructed with the Belle II detector in a sample of asymmetric-energy electron-positron collisions at the resonance corresponding to 62.8 of integrated luminosity. The results are , , , and . The results are consistent with previous measurements and show a detector performance comparable with early Belle performance.
In this work, we explore macroscopic transport phenomena associated with a rotational system in the presence of an external orthogonal electromagnetic field. Simply based on the lowest Landau level approximation, we derive nontrivial expressions for chiral density and various currents consistently by adopting small angular velocity expansion or Kubo formula. While the generation of anomalous electric current is due to the pseudo gauge field effect of the spin-rotation coupling, the chiral density and current can be simply explained with the help of Lorentz boosts. Finally, Lorentz covariant forms can be obtained by unifying our results and the magnetovorticity effect.
At leading order, the -matrices in QED and gravity are known to factorise, providing unambiguous determinations of the parts divergent due to infrared contributions. The soft -matrices defined in this fashion are shown to be defined entirely in terms of dimensional models on the celestial sphere, involving two real scalar fields, allowing us to express the soft -matrices for real as well as virtual divergences as two dimensional correlation functions. We discuss what this means for finding holographic representations of scattering amplitudes in QED and gravity and comment on simple double copy structures that arise during the analysis.
Anders Andreassen🇺🇸 · Patrick T. Komiske🇺🇸 · Eric M. Metodiev🇺🇸 · Benjamin Nachman🇺🇸 · Adi Suresh🇺🇸 · Jesse Thaler🇺🇸
A common setting for scientific inference is the ability to sample from a high-fidelity forward model (simulation) without having an explicit probability density of the data. We propose a simulation-based maximum likelihood deconvolution approach in this setting called OmniFold. Deep learning enables this approach to be naturally unbinned and (variable-, and) high-dimensional. In contrast to model parameter estimation, the goal of deconvolution is to remove detector distortions in order to enable a variety of down-stream inference tasks. Our approach is the deep learning generalization of the common Richardson-Lucy approach that is also called Iterative Bayesian Unfolding in particle physics. We show how OmniFold can not only remove detector distortions, but it can also account for noise processes and acceptance effects.
Maurício Hippert🇺🇸 · Eduardo S. Fraga🇧🇷 · Jorge Noronha🇺🇸
In this work we investigate the minimal physical requirements needed for generating a speed of sound that surpasses its asymptotic conformal limit. It is shown that a peak in the speed of sound of homogeneous matter naturally emerges in the transition from a phase with broken chiral symmetry to one with a gapped Fermi surface. We argue that this could be relevant for understanding the peak in the speed of sound displayed by some of the current models for cold ultradense matter. A minimal model implementation of this mechanism is presented, based on the spontaneous breakdown of an approximate particle-antiparticle symmetry, and its thermodynamic properties are determined.
M. Battaglieri🇺🇸 · A. Bianconi🇮🇹 · P. Bisio🇮🇹 · M. Bondì🇮🇹 · A. Celentano🇮🇹 · G. Costantini🇮🇹 · P. L. Cole🇺🇸 · L. Darmé🇮🇹 · R. De Vita🇮🇹 · A. D'Angelo🇮🇹 · M. De Napoli🇮🇹 · L. El Fassi🇺🇸 and 19 other authors
We discuss two complementary strategies to search for light dark matter (LDM) exploiting the positron beam possibly available in the future at Jefferson Laboratory. LDM is a new compelling hypothesis that identifies dark matter with new sub-GeV "hidden sector" states, neutral under standard model interactions and interacting with our world through a new force. Accelerator-based searches at the intensity frontier are uniquely suited to explore it. Thanks to the high intensity and the high energy of the CEBAF (Continuous Electron Beam Accelerator Facility) beam, and relying on a novel LDM production mechanism via positron annihilation on target atomic electrons, the proposed strategies will allow us to explore new regions in the LDM parameters space, thoroughly probing the LDM hypothesis as well as more general hidden sector scenarios.
Jeff A. Dror🇺🇸 · Benjamin V. Lehmann🇺🇸 · Hiren H. Patel🇺🇸 · Stefano Profumo🇺🇸
Supermassive black hole binary mergers generate a stochastic gravitational wave background detectable by pulsar timing arrays. While the amplitude of this background is subject to significant uncertainties, the frequency dependence is a robust prediction of general relativity. We show that the effects of new forces beyond the Standard Model can modify this prediction and introduce unique features into the spectral shape. In particular, we consider the possibility that black holes in binaries are charged under a new long-range force, and we find that pulsar timing arrays are capable of robustly detecting such forces. Supermassive black holes and their environments can acquire charge due to high-energy particle production or dark sector interactions, making the measurement of the spectral shape a powerful test of fundamental physics.
Xin Ren🇨🇳 · Yaqi Zhao🇨🇳 · Emmanuel N. Saridakis🇬🇷 · Yi-Fu Cai🇨🇳
We calculate the deflection angle, as well as the positions and magnifications of the lensed images, in the case of covariant gravity. We first extract the spherically symmetric solutions for both the pure-tetrad and the covariant formulation of the theory, since considering spherical solutions the extension to the latter is crucial, in order for the results not to suffer from frame-dependent artifacts. Applying the weak-field, perturbative approximation we extract the deviations of the solutions comparing to General Relativity. Furthermore, we calculate the deflection angle and then the differences of the positions and magnifications in the lensing framework. This effect of consistent gravity on the lensing features can serve as an observable signature in the realistic cases where is expected to deviate only slightly from General Relativity, since lensing scales in general are not restricted as in the case of Solar System data, and therefore deviations from General Relativity could be observed more easily.
The quantum to classical transition of fluctuations in the early universe is still not completely understood. Some headway has been made incorporating the effects of decoherence and the squeezing of states, though the methods and procedures continue to be challenged. But new developments in the analysis of the most recent Planck data suggest that the primordial power spectrum has a cutoff associated with the very first quantum fluctuation to have emerged into the semi-classical universe from the Planck domain at about the Planck time. In this paper, we examine the implications of this result on the question of classicalization, and demonstrate that the birth of quantum fluctuations at the Planck scale would have been a `process' supplanting the need for a `measurement' in quantum mechanics. Emerging with a single wavenumber, these fluctuations would have avoided the interference between different degrees of freedom in a superposed state. Moreover, the implied scalar-field potential had an equation-of-state consistent with the zero active mass condition in general relativity, allowing the quantum fluctuations to emerge in their ground state with a time-independent frequency. They were therefore effectively quantum harmonic oscillators with classical correlations in phase space from the very beginning.
* 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.