HEP Phenomenology·hep-ph
44 papers—31 primary·13 cross-listed·reconstructed*
Fatma P. Aslan🇺🇸 · Matthias Burkardt🇺🇸
We calculate twist-3 parton ditribution functions (PDFs) using cut and uncut diagrams. Uncut diagrams lead to a Dirac delta function term. No such term appears when cut diagrams are used. We show that a is necessary to satisfy the Lorentz invariance relations of twist-3 PDFs, except for the Burkhardt-Cottingham sum rule in QCD.
Christopher Leon🇺🇸 · Misak Sargsian🇺🇸
We present a new approach for the calculation of the valence quark distributions in the nucleon based on the scenario in which the spectrum of the valence quarks at x>0.05 is generated through three main mechanisms: interaction of valence quarks with the mean field generated by the residual nucleon system, two and three quark short range interactions through gluon exchanges. In the current report we present the first phase of the project in which we develop a non-perturbative model for valence quark interaction in the mean field of the nucleonic interior to describe their distribution in the moderate x region (0.05 < x < 0.4). The short range quark-quark interaction effects in our approach generate the high x tail of valence quark distributions. The presented non-perturbative model is based on the picture in which three relativistic valence quarks occupy the nucleon core at distances of Fm while interacting in the mean field generated by the residual nucleon system. The calculations are based on the assumption of the a factorization of the internal interaction of short-range three valence quarks with the long-range interaction of these quarks with the residual system. The theoretical approach is based on effective light-front diagrammatic approach which allows us to introduce the valence quark and residual system wave functions in a consistent way The parameters of these wave functions are fixed by the position of the peak of the xf_q(x) distribution of valence quarks at Q_0 corresponding to the charm-quark mass. With few parameters we achieved a very reasonable description of the up and down valence quark distributions in the moderate x region (x < 0.4), where one expects the mean field dynamics to dominate. The model, however, systematically underestimates the high region where enhanced contributions from partonic short-range correlations are expected.
Spencer R. Klein🇺🇸 · Sally A. Robertson🇺🇸 · Ramona Vogt🇺🇸
Neutrino telescopes like IceCube, KM3NeT and Baikal-GVD offer physicists the opportunity to study neutrinos with energies far beyond the reach of terrestrial accelerators. These neutrinos are used to study high-energy neutrino interactions and to probe the Earth through absorption tomography. Current studies of TeV neutrinos use cross sections which are calculated for free nucleons with targets which are assumed to contain equal numbers of protons and neutrons. Here we consider modifications of high-energy neutrino interactions due to two nuclear effects: modifications of the parton densities in the nucleus, referred to here as shadowing, and the effect of non-isoscalar targets, with unequal numbers of neutrons and protons. Both these effects depend on the interaction medium. Because shadowing is larger for heavier nuclei, such as iron, found in the Earth's core, it introduces a zenith-angle dependent change in the absorption cross section. These modifications increase the cross sections by 1-2\% at energies below 100 TeV (antishadowing), and reduce it by 3-4\% at higher energies (shadowing). Nuclear effects also alter the inelasticity distribution of neutrino interactions in water/ice by increasing the number of low inelasticity interactions, with a larger effect for than . These effects are particularly large in the energy range below a few TeV. These effects could alter the cross sections inferred from events with tracks originating within the active detector volume as well as the ratio inferred from inelasticity measurements. The uncertainties in these nuclear effects are larger than the uncertainties on the free-proton cross sections and will thus limit the systematic precision of future high-precision measurements at neutrino telescopes.
Pavel Pustoshny🇷🇺 · Vadim Shakhov🇷🇺 · Alexander Studenikin🇷🇺
After a brief history of two known types of neutrino mixing and oscillations, including neutrino spin and spin-flavour oscillations in the transversal magnetic field, we perform systematic study of a new phenomenon of neutrino spin and spin-flavour oscillations engendered by the transversal matter currents on the bases of the developed quantum treatment of the phenomenon. Possibilities for the resonance amplification of these new types of oscillations by the longitudinal matter currents and longitudinal magnetic fields are analyzed. We also consider modifications of the oscillation probabilities due to possible arbitrary orientation of the magnetic field vector and the matter velocity .
The difference between the quark orbital angular momentum (OAM) defined in light-cone gauge (Jaffe-Manohar) compared to defined using a local manifestly gauge invariant operator (Ji) is interpreted in terms of the change in quark OAM as the quark leaves the target in a DIS experiment.
M. J. Mueterthies🇺🇸 · E. Fischbach🇺🇸 · V. E. Barnes🇺🇸 · J. Bertaux🇺🇸 · D. E. Krause🇺🇸 · A. Longman🇺🇸
We present a generalized phenomenological formalism for analyzing the original Eötvös experiment in the presence of gravity and a generic "5th force." To date no evidence for a 5th force has emerged since its presence was suggested by a 1986 reanalysis of the 1922 publication coauthored by Eötvös, Pekàr, and Fekete (EPF). However, our generalized analysis introduces new mechanisms capable in principle of accounting for the EPF data, while at the same time avoiding detection by most recent experiments carried out to date. As an example, some of these mechanisms raise the possibility that the EPF signal could have arisen from an unexpected direction if it originated from the motion of the Earth through a medium.
Phung Van Dong🇻🇳 · Duong Van Loi🇻🇳
The present matter content of our universe may be governed by a symmetry -- the simplest gauge completion of the seesaw mechanism which produces small neutrino masses. The matter parity results as a residual gauge symmetry, implying dark matter stability. The Higgs field that breaks the charge inflates the early universe successfully and then decays to right-handed neutrinos, which reheats the universe and generates both normal matter and dark matter manifestly.
Vladimir Dzhunushaliev🇰🇿 · Vladimir Folomeev🇰🇿 · Albina Serikbolova🇰🇿
Monopole solutions in SU(2) Yang-Mills theory which includes spinor fields described by the nonlinear Dirac equation are obtained. It is demonstrated that the energy spectrum of such a system possesses a global minimum whose appearance is brought about solely by the nonlinear spinor fields. It is shown that the monopole solution obtained differs in principle from the 't~Hooft-Polyakov monopole in that it is topologically trivial.
Yoshihiko Abe🇯🇵 · Takashi Toma🇨🇦 · Koji Tsumura🇯🇵
A pseudo-Nambu-Goldstone boson (pNGB) is an attractive candidate for dark matter since the current severe limits of dark matter direct detection experiments are naturally evaded by its nature. We construct a model with pNGB dark matter based on a {\it gauged} symmetry, where no ad-hoc global symmetry is assumed. The model keeps natural suppression mechanism for the dark matter direct detection cross section. On the other hand, the pNGB can decay through the new high scale suppressed operators. We show that the pNGB has long enough lifetime to be a dark matter in the wide range of the parameter space of the model. The thermal relic abundance of pNGB dark matter can be fit with the observed value against the constraints on the dark matter decays from the cosmic-ray observations.
Uwe Hernandez Acosta🇩🇪 · Andreas Otto🇩🇪 · Burkhard Kämpfer🇩🇪 · Alexander I. Titov🇷🇺
The probabilities of various elementary laser - photon - electron/positron interactions display in selected phase space and parameter regions typical non-perturbative dependencies such as , where is a pre-exponential factor, denotes the critical Sauter-Schwinger field strength, and characterizes the (laser) field strength. While the Schwinger process with and the non-linear Breit-Wheeler process in the tunneling regime with (with the probe photon energy and the electron/positron mass) are famous results, we point out here that also the non-linear Compton scattering exhibits a similar behavior when focusing on high harmonics. Using a suitable cut-off , the factor becomes . This opens the avenue towards a new signature of the boiling point of the vacuum even for field strengths below by employing a high electron beam-energy to counter balance the large ratio by a small factor to achieve . In the weak-field regime, the cut-off facilitates a threshold leading to multi-photon signatures showing up in the total cross section at sub-threshold energies.
Cesar Ayala🇨🇱 · Gorazd Cvetic🇨🇱 · Lorena Gonzalez🇨🇱
We evaluate QCD effects in the neutrinoless double beta () decay, originating from new physics short-range mechanism in the form of five dimension-9 operators. For this, we employ the one-loop and two-loop renormalization group equations (RGEs) for the corresponding Wilson coefficients, performing the RGE-evolution from the new physics scales (estimated as GeV) to the typical spacelike -scale GeV. Since the latter scale is clearly nonperturbative, we apply various infrared-safe (IR-safe) variants of QCD where the running coupling has no Landau singularities at low spacelike . We point out that the correct treatment of the IR-safe analogs of the (noninteger) powers of the couplings is important. It turns out that in most cases of the considered operators the resulting QCD effects can be significant in this process, i.e., can be stronger than the effects of the present uncertainties in the nuclear matrix elements.
M. Jay Pérez🇺🇸 · Moinul Hossain Rahat🇺🇸 · Pierre Ramond🇺🇸 · Alexander J. Stuart🇲🇽 · Bin Xu🇺🇸
We extend the recently proposed model for the asymmetric texture to the up-type quark and seesaw sectors. The hierarchical up-type quark masses are generated from higher-dimensional operators involving family-singlet Higgses, gauge-singlet familons, and vectorlike messengers. The complex-tribimaximal (TBM) seesaw mixing arises from the vacuum structure of a minimal number of familons, resulting in an alignment between the Yukawa and Majorana matrices of the seesaw formula. Introducing four right-handed neutrinos, normal ordering of the light neutrino masses is obtained, with , and . Their sum almost saturates Planck's cosmological upper bound ( ). The right-handed neutrino masses are expressed in terms of two parameters for a particular choice of familon vacuum alignment. We predict the Jarlskog-Greenberg invariant to be , consistent with the current PDG estimate, and Majorana invariants and . A sign ambiguity in the model parameters leads to two possibilities for the invariant mass parameter : or , both within an order of magnitude of the most rigorous experimental upper limit (-- ).
Pritam Das🇮🇳 · Mrinal Kumar Das🇮🇳 · Najimuddin Khan🇮🇳
We study a simplest viable dark matter model with a real singlet scalar, vector-like singlet and a doublet lepton. We find a considerable enhancement in the allowed region of the scalar dark matter parameter spaces under the influence of the new Yukawa coupling. The Yukawa coupling associate with the fermion sector heavily dominant the dark matter parameter spaces satisfying the current relic density of the Universe. Dilepton signature arising from the new fermionic sector can observe at Large Hadron Collider (LHC). We perform such analysis in the context of 14 TeV LHC experiments with a future integrated luminosity of 3000 . We found that a large region of the parameter spaces can be probed by the LHC experiments. The projected exclusion/discovery reach of direct heavy charged fermion searches in this channels is analyzed by performing a detailed cut based collider analysis. The projected exclusion contour reaches up to for 3000 for a light dark matter GeV from searches in the channel.
Chengcheng Han🇨🇳 · M.L. López-Ibáñez🇨🇳 · Bo Peng🇨🇳 · Jin Min Yang🇨🇳
We investigate a gauge extension of the Standard Model (SM) where the gauge boson mass is generated by the Stueckelberg mechanism. Three right-handed neutrinos are added to cancel the gauge anomaly and hence the neutrino masses can be explained. A new Dirac fermion could be a WIMP dark matter whose interaction with the SM sector is mediated by the new gauge boson. Assuming the perturbativity of the gauge coupling up to the Planck scale, we find that only the resonance region is feasible for the dark matter abundance. After applying the constraints from the current Planck experiment, the collider search constraints as well as the dark matter direct detection limits, we observe that the charge of dark matter satisfies . Such a scenario might be probed conclusively by the projected CMB-S4 experiment, assuming the right-handed neutrinos are thermalized with the SM sector in the early universe.
Hsiang-nan Li🇹🇼 · Hiroyuki Umeeda🇹🇼 · Fanrong Xu🇨🇳 · Fu-Sheng Yu🇨🇳
We calculate the parameters and for the meson mixing in the Standard Model by considering a dispersion relation between them. The dispersion relation for a fictitious charm quark of arbitrary mass squared is turned into an inverse problem, via which the mixing parameters at low are solved with the perturbative inputs and from large . It is shown that nontrivial solutions for and exist, whose values around the physical charm scale agree with the data in both CP-conserving and CP-violating cases. We then predict the observables and degrees associated with the coefficient ratio for the meson mixing, which can be confronted with more precise future measurements. Our work represents the first successful quantitative attempt to explain the meson mixing parameters in the Standard Model.
Ang Liu🇨🇳 · Zhi-Long Han🇨🇳 · Yi Jin🇨🇳 · Fa-Xin Yang🇨🇳
In this paper, we perform a detail analysis on leptogenesis and dark matter form low scale seesaw. In the framework of 2HDM, we further introduce one scalar singlet and one Dirac fermion singlet , which are charged under a symmetry. Assuming the coupling of is extremely small, it serves as a FIMP dark matter. The heavy right hand neutrinos provide a common origin for tiny neutrino mass (via seesaw mechanism), leptogenesis (via ) and dark matter (via ). With hierarchical right hand neutrino masses, the explicit calculation shows that success thermal leptogenesis is viable even for TeV scale with GeV and lightest neutrino mass eV. In such scenario, light FIMP dark matter in the keV to MeV range is naturally expected. The common parameter space for neutrino mass, natural leptogenesis and FIMP DM is also obtained in this paper.
The quarks and gluons are confined objects, they cannot be put on the mass-shell, it is questionable to apply the Landau equation to study the Feynman diagrams in the QCD sum rules. Furthermore, we carry out the operator product expansion in the deep Euclidean region , where the Landau singularities cannot exist. The Landau equation servers as a kinematical equation in the momentum space, and is independent on the factorizable and nonfactorizable properties of the Feynman diagrams in the color space. The meson-meson scattering state and tetraquark molecular state both have four valence quarks, which form two color-neutral clusters, we cannot distinguish the contributions based on the two color-neutral clusters in the factorizable Feynman diagrams. Lucha, Melikhov and Sazdjian assert that the contributions at the order with in the operator product expansion, which are factorizable in the color space, are exactly canceled out by the meson-meson scattering states at the hadron side, the tetraquark molecular states begin to receive contributions at the order . Such an assertion is questionable, we refute the assertion in details, and choose an axialvector current and a tensor current to examine the outcome of the assertion. After detailed analysis, we observe that the meson-meson scattering states cannot saturate the QCD sum rules, while the tetraquark molecular states can saturate the QCD sum rules. The Landau equation is of no use to study the Feynman diagrams in the QCD sum rules for the tetraquark molecular states, the tetraquark molecular states begin to receive contributions at the order rather than at the order .
E. M. Priidik Gallagher🇪🇪 · Stefan Groote🇪🇪 · Maria Naeem🇪🇪
The propagator of a gauge boson, like the massless photon or the massive vector bosons and of the electroweak theory, can be derived in two different ways, namely via Green's functions (semi-classical approach) or via the vacuum expectation value of the time-ordered product of the field operators (field theoretical approach). Comparing the semi-classical with the field theoretical approach, the central tensorial object can be defined as the gauge boson projector, directly related to the completeness relation for the complete set of polarisation four-vectors. In this paper we explain the relation for this projector to different cases of the gauge and explain why the unitary gauge is the default gauge for massive gauge bosons.
We propose to accommodate economically the type-II neutrino seesaw mechanism in (G)NMSSM from GMSB and AMSB, respectively. The heavy triplets within neutrino seesaw mechanism are identified to be the messengers. Therefore, the -problem, the neutrino mass generation, LFV as well the soft SUSY breaking parameters can be economically combined in a non-trivial way. General features of such extensions are discussed. The type-II neutrino seesaw-specific interactions can give additional Yukawa deflection contributions to the soft SUSY breaking parameters of NMSSM, which are indispensable to realize successful EWSB and accommodate the 125 GeV Higgs. Relevant numerical results, including the constraints of dark matter and possible LFV processes etc, are also given. We find that our economical type-II neutrino seesaw mechanism extension of NMSSM from AMSB or GMSB can lead to realistic low energy NMSSM spectrum, both admitting the 125 GeV Higgs as the lightest CP-even scalar. The possibility of the 125 GeV Higgs being the next-to-lightest CP-even scalar in GMSB-type scenario is ruled out by the constraints from EWSB, collider and precision measurements. The possibility of the 125 GeV Higgs being the next-to-lightest CP-even scalar in AMSB-type scenario is ruled out by dark matter direct detection experiments. Possible constraints from LFV processes can give an upper bound for the messenger scale.
We propose a new method to determine the spatially or impact-parameter dependent nuclear parton distribution functions (nPDFs) using the double parton scattering (DPS) processes in high-energy heavy-ion (proton-nucleus and nucleus-nucleus) collisions. We derive a simple generic DPS formula in nuclear collisions by accommodating both the nuclear collision geometry and the spatially dependent nuclear modification effect, under the assumption that the impact-parameter dependence of nPDFs is only related to the nuclear thickness function. While the geometric effect is widely adopted, the impact of the spatially dependent nuclear modification on DPS cross sections has been overlooked so far, which can, however, be significant when the initial nuclear modification is large. In turn, the DPS cross sections in heavy-ion collisions can provide useful information on the spatial dependence of nPDFs. They can be, in general, obtained in minimum-bias nuclear collisions, featuring the virtue of independence of Glauber modeling.
Xin Chen🇨🇳 · Zhen Hu🇨🇳 · Yongcheng Wu🇨🇦 · Kai Yi🇨🇳
The search for a dark photon produced at colliders which subsequently decays into inelastic dark matter particles, is discussed. The heavier dark matter decays into a pair of visible charged particles and a lighter dark matter particle after traveling some distance. The visible decay products can be recorded by a dark matter detector made of emulsions and gas detectors, placed near the main detector. This setup can not only explore new parameter regions not reached before, but also re-open some regions thought to be excluded by previous experimental data. The physics potential for such a detector around BESIII and Belle II is presented.
Ashutosh Kumar Alok🇮🇳 · Suman Kumbhakar🇮🇳 · S. Uma Sankar🇮🇳
A number of observables related to the transition show deviations from their standard model predictions. A global fit to the current data suggests several new physics solutions. Considering only one operator at a time and new physics only in the muon sector, it has been shown that the new physics scenarios (I) , (II) , (III) can account for all data. In this work, we develop a procedure to uniquely identify the correct new physics solution. The scenario II predicts a significantly lower value of and can be distinguished from the other two scenarios if the experimental uncertainty comes down by a factor of three. On the other hand, a precise measurement of the CP averaged angular observables in high bin of decay can uniquely discriminate between the other two scenarios. We propose new methods, in terms of azimuthal angle asymmetries, to measure with the necessary precision.
Vladyslav Shtabovenko🇩🇪 · Rolf Mertig🇩🇪 · Frederik Orellana🇩🇰
We present FeynCalc 9.3, a new stable version of a powerful and versatile Mathematica package for symbolic quantum field theory (QFT) calculations. Some interesting new features such as highly improved interoperability with other packages, automatic extraction of the ultraviolet divergent parts of 1-loop integrals, support for amplitudes with Majorana fermions and -matrices with explicit Dirac indices are explained in detail. Furthermore, we discuss some common problems and misunderstandings that may arise in the daily usage of the package, providing explanations and workarounds.
Chandan Mondal🇨🇳 · Siqi Xu🇨🇳 · Jiangshan Lan🇨🇳 · Xingbo Zhao🇨🇳 · Yang Li🇺🇸 · Dipankar Chakrabarti🇮🇳 · James P. Vary🇺🇸
We obtain the light-front wavefunctions for the nucleon in the valence quark Fock space from an effective Hamiltonian, which includes the transverse and longitudinal confinement and the one-gluon exchange interaction with fixed coupling. The wavefunctions are generated by solving the eigenvalue equation in a basis light-front quantization. Fitting the model parameters, the wavefunctions lead to good simultaneous description of electromagnetic form factors, radii, and parton distribution functions for the proton.
Hiroki Matsui🇯🇵 · Fuminobu Takahashi🇯🇵 · Wen Yin🇰🇷
The abundance of the QCD axion is known to be suppressed if the Hubble parameter during inflation, , is lower than the QCD scale, and if the inflation lasts sufficiently long. We show that the tight upper bound on the inflation scale can be significantly relaxed if the eternal old inflation is driven by the standard-model Higgs field trapped in a false vacuum at large field values. Specifically, can be larger than GeV if the false vacuum is located above the intermediate scale. We also discuss the slow-roll inflation after the tunneling from the false vacuum to the electroweak vacuum.
Precision measurements of the number of effective relativistic neutrino species and the primordial element abundances require accurate theoretical predictions for early Universe observables in the Standard Model and beyond. Given the complexity of accurately modelling the thermal history of the early Universe, in this work, we extend a previous method presented by the author to obtain simple, fast and accurate early Universe thermodynamics. The method is based upon the approximation that all relevant species can be described by thermal equilibrium distribution functions characterized by a temperature and a chemical potential. We apply the method to neutrino decoupling in the Standard Model and find -- a result in excellent agreement with previous state-of-the-art calculations. We apply the method to study the thermal history of the Universe in the presence of a very light () and weakly coupled () neutrinophilic scalar. We find our results to be in excellent agreement with the solution to the exact Liouville equation. Finally, we release a code: NUDEC_BSM (available in both Mathematica and Python formats), with which neutrino decoupling can be accurately and efficiently solved in the Standard Model and beyond: https://github.com/MiguelEA/nudec_BSM .
Claudia Cornella🇨🇭 · Gino Isidori🇨🇭 · Matthias König🇨🇭 · Sascha Liechti🇨🇭 · Patrick Owen🇨🇭 · Nicola Serra🇨🇭
We investigate the possibility of indirectly constraining the decay rate using precise data on the dimuon spectrum. To this end, we estimate the distortion of the spectrum induced by the re-scattering process, and propose a method to simultaneously constrain this (non-standard) contribution and the long-distance effects associated to hadronic intermediate states. The latter are constrained using the analytic properties of the amplitude combined with data and perturbative calculations. Finally, we estimate the sensitivity expected at the LHCb experiment with present and future datasets. We find that constraints on the branching fraction of , competitive with current direct bounds, can be achieved with the current dataset, while bounds of could be obtained with the LHCb upgrade-II luminosity.
Minyuan Jiang🇨🇳 · Jing Shu🇨🇳 · Ming-Lei Xiao🇨🇳 · Yu-Hui Zheng🇨🇳
We derive the generalized partial wave expansion for scattering amplitude in terms of spinor helicity variables. The basis amplitudes of the expansion with definite angular momentum consist of the Poincare Clebsch-Gordan coefficients, while constrains the UV physics that could generate the corresponding operators at tree level. Moreover, we obtain a series of selection rules that restrict the anomalous dimension matrix of effective operators and the way how effective operators contribute to some amplitudes at the loop level.
We revisit the gauge hierarchy problem with the emphasis on the chiral property of the Standard Model. We present a model realizing a gauge hierarchy. Along this line, we also comment briefly on the "very light" axions and the upper bound on .
António P. Morais🇵🇹 · Roman Pasechnik🇸🇪 · Werner Porod🇩🇪
Tremendous phenomenological success of the Standard Model (SM) suggests that its flavor structure and gauge interactions may not be arbitrary but should have a fundamental first-principle explanation. In this work, we explore how the basic distinctive properties of the SM dynamically emerge from a unified New Physics framework tying together both flavour physics and Grand Unified Theory (GUT) concepts. This framework is suggested by a novel anomaly-free supersymmetric chiral GUT containing the SM. Among the most appealing emergent properties of this theory is the Higgs-matter unification with a highly-constrained massless chiral sector featuring two universal Yukawa couplings close to the GUT scale. At the electroweak scale, the minimal SM-like effective field theory limit of this GUT represents a specific flavored three-Higgs doublet model consistent with the observed large hierarchies in the quark mass spectra and mixing already at tree level.
Gregor Kasieczka🇩🇪 · David Shih🇺🇸
While deep learning has proven to be extremely successful at supervised classification tasks at the LHC and beyond, for practical applications, raw classification accuracy is often not the only consideration. One crucial issue is the stability of network predictions, either versus changes of individual features of the input data, or against systematic perturbations. We present a new method based on a novel application of "distance correlation" (DisCo), a measure quantifying non-linear correlations, that achieves equal performance to state-of-the-art adversarial decorrelation networks but is much simpler and more stable to train. To demonstrate the effectiveness of our method, we carefully recast a recent ATLAS study of decorrelation methods as applied to boosted, hadronic W-tagging. We also show the feasibility of DisCo regularization for more powerful convolutional neural networks, as well as for the problem of hadronic top tagging.
Mohamed M. Anber🇺🇸 · Erich Poppitz🇨🇦
We study gauge theories with Dirac fermions in representations of nonzero -ality, coupled to axions. These theories have an exact discrete chiral symmetry, which has a mixed 't Hooft anomaly with general baryon-color-flavor backgrounds, called the "BCF anomaly" in arXiv:1909.09027. The infrared theory also has an emergent -form center symmetry. We show that the BCF anomaly is matched in the infrared by axion domain walls. We argue that is spontaneously broken on axion domain walls, so that nonzero -ality Wilson loops obey the perimeter law and probe quarks are deconfined on the walls. We give further support to our conclusion by using a calculable small-circle compactification to study the multi-scale structure of the axion domain walls and the microscopic physics of deconfinement on their worldvolume.
Heavy-ion colliders have revealed the process of "fast thermalization". This experimental breakthrough has led to new theoretical tools to study the thermalization process at both weak and strong coupling. We apply this to the reheating epoch of inflationary cosmology, and the formation of a cosmological quark gluon plasma (QGP). We compute the thermalization time of the QGP at reheating, and find it is determined by the energy scale of inflation and the shear viscosity to entropy ratio ; or equivalently, the tensor-to-scalar ratio and the strong coupling constant at the epoch of thermalization. Thermalization is achieved near-instantaneously in low-scale inflation and in strongly coupled systems, and takes of order or less than a single e-fold of expansion for weakly-coupled systems or after high-scale inflation. We demonstrate that the predictions of inflation are robust to the physics of thermalization, and find a stochastic background of gravitational waves at frequencies accessible by interferometers, albeit with a small amplitude.
Yi Wang🇨🇳 · Yuhang Zhu🇨🇳
The cosmological collider provides a model-independent probe of particle physics during inflation. We extend the study of cosmological collider physics to much smaller scales through gravitational wave (GW) probes. With a Chern-Simons interaction, a massive vector field can obtain a chemical potential and its particle production can cause significant non-Gaussian GW signals. We calculate the mass and spin dependences of the induced GW 3-point correlation function in the squeezed limit, and estimate its amplitude. Such signals may be detectable in the current and upcoming GW interferometer experiments.
Hermann Krebs🇩🇪 · Evgeny Epelbaum🇩🇪 · Ulf-G. Meißner🇩🇪
Recently, we have worked out the axial two-nucleon current operator to leading one-loop order in chiral effective field theory using the method of unitary transformation. Our final expressions, however, differ from the ones derived by the JLab-Pisa group using time-ordered perturbation theory (Phys. Rev. C 93, no. 1, 015501 (2016) Erratum: [Phys. Rev. C 93, no. 4, 049902 (2016)] Erratum: [Phys. Rev. C 95, no. 5, 059901 (2017)]). In this paper we consider the box diagram contribution to the axial current and demonstrate that the results obtained using the two methods are unitary equivalent at the Fock-space level. We adjust the unitary phases by matching the corresponding two-pion exchange nucleon-nucleon potentials and rederive the box diagram contribution to the axial current operator following the approach of the JLab-Pisa group, thereby reproducing our original result. We provide a detailed information on the calculation including the relevant intermediate steps in order to facilitate a clarification of this disagreement.
For the first time, elastic pion-nucleon scattering is analyzed in the framework of chiral perturbation theory up to fourth order with explicit degrees of freedom. The analysis is performed within the heavy-baryon expansion as well as in a covariant approach based on an extended on-mass-shell renormalization scheme. The renormalization of low-energy constants in both chiral approaches is discussed in detail and the explicit expressions to cancel both power-counting breaking as well as decoupling breaking terms are given. The low-energy constants from the interaction as well as additional constants from the sector are reliably constrained by fits to experimental data. The traditional -matrix unitarization is employed in the near threshold region, whereas a complex mass approach is used to extend the applicability of the theory up to the pole region. Additionally, we estimate a theoretical error based on the truncation of the chiral series as employed in recent analyses of nuclear forces as well as pion-nucleon scattering. The obtained results provide a clear evidence that the explicit inclusion of degrees of freedom is fundamental to describe pion-nucleon physics at threshold. The resulting predictions for the subthreshold and threshold parameters as well as phase shifts are in excellent agreement with the ones determined by the recent Roy-Steiner analysis of pion-nucleon scattering.
Debmalya Mukhopadhyay🇮🇳 · Jan-e Alam🇮🇳 · R. Kumar🇮🇳
In this work, we show the dependence of bulk viscosity on Polyakov loop in 3+1 dimensional topologically massive model (TMM). This model contains equally massive non-Abelian gauge fields without spontaneous symmetry breaking. In earlier works, the bulk viscosity was found from the trace anomaly in massless model and Yang-Mills (YM) theory and its dependence on the quantum corrections was established. In TMM, the trace anomaly is absent due to the presence of kinetic term of a two-form field in the action. This model also provides the dependence of bulk viscosity on the mass of the gauge bosons. The mass of the gauge bosons in TMM acts as magnetic mass in the perturbative thermal field theory. This magnetic mass is gauge independent unlike what is found in massless YM theory. The ratio of bulk viscosity and entropy density vs temperature is plotted which shows the required behaviour near critical point. We also observe that the strong coupling constant has the same behaviour at high energy limit (i.e. asymptotic freedom) as that of massless YM theory at zero temperature.
A. S. Bakry🇨🇳 · M. A. Deliyergiyev🇵🇱 · A. A. Galal🇪🇬 · M. Khalil William🇪🇬
We investigate the implications of Nambu-Goto (NG), Lüscher-Weisz (LW) and Polyakov-Kleinert (PK) string actions for the Casimir energy of the QCD flux-tube at one and two loop order at finite temperature. We perform our numerical study on the 4-dim pure SU(3) Yang-Mills lattice gauge theory at finite temperature . The static quark-antiquark potential is calculated using link-integrated Polyakov loop correlators. At a high temperature-close to the critical point- We find that the rigidity and self-interactions effects of the QCD string to become detectable. The remarkable feature of this model is that it retrieves a correct dependency of the renormalized string tension on the temperature. Good fit to static potential data at source separations fm is obtained when including additional two-boundary terms of (LW) action. On the other-hand, at a lower temperature-near the QCD plateau- We detect signatures of two boundary terms of the Lüscher-Weisz (LW) string action. The (LW) string with boundary action is yielding a static potential which is in a good agreement with the lattice data, however, for color source separation as short as fm.
Jacob Egge🇩🇪 · Stefan Knirck🇩🇪 · Béla Majorovits🇩🇪 · Christopher Moore🇩🇪 · Olaf Reimann🇩🇪
Axions and axion-like particles are excellent low-mass dark matter candidates. The MADMAX experiment aims to directly detect galactic axions with masses between and by using the axion-induced emission of electromagnetic waves from boundaries between materials of different dielectric constants under a strong magnetic field. Combining many such surfaces, this emission can be significantly enhanced (boosted) using constructive interference and resonances. We present a first proof of principle realization of such a booster system consisting of a copper mirror and up to five sapphire disks. The electromagnetic response of the system is investigated by reflectivity measurements. The mechanical accuracy, calibration process of unwanted reflections and the repeatability of a basic tuning algorithm to place the disks are investigated. We find that for the presented cases the electromagnetic response in terms of the group delay predicted by one-dimensional calculations is sufficiently realized in our setup. The repeatability of the tuning is at the percent level, and would have small impact on the sensitivity of such a booster.
V. De Luca🇨🇭 · G. Franciolini🇨🇭 · A. Riotto🇨🇭
We elaborate on the mass function of primordial black holes in the case in which the power spectrum of the curvature perturbation is broad. For the case of a broad and flat spectrum, we argue that such a mass function is peaked at the smallest primordial black mass which can be formed and possesses a tail decaying like , where is the mass of the primordial black hole.
B. Blankleider🇦🇺 · S. S. Kumar🇦🇺 · A. N. Kvinikhidze🇬🇪
The effect of nucleon dressing by pions, on the binding energy of three nucleons interacting via two-body forces, is calculated for the first time within a conventional nuclear physics approach. It is found that the dressing increases the binding energy of the triton by an amount approximately in the range from 0.3 MeV to 0.9 MeV, depending on the model used for dressing. This suggests that nucleon dressing may help explain the underestimation of the triton binding energy in previous calculations using only two-nucleon forces.
G. Aarts🇬🇧 · C. Allton🇬🇧 · D. De Boni🇬🇧 · J. Glesaaen🇬🇧 · S. Hands🇬🇧 · B. Jäger🇩🇰 · A.A. Nikolaev🇬🇧 · J.-I. Skullerud🇮🇪 · L.-K. Wu🇨🇳
In order to study the fate of mesons in thermal QCD at finite baryon chemical potential, we consider light mesonic correlation functions using the Taylor expansion to , in both the hadronic and quark-gluon plasma phases. We use the FASTSUM anisotropic fixed-scale lattices with flavours of Wilson fermion. We find that mesonic correlators are sensitive to finite-density corrections and that the second-order terms indicate the chiral crossover in the vector and axial-vector channels.
Norma G. Sanchez (CNRS, LERMA PSL University Observatoire de Paris, Sorbonne University)🇫🇷
This White Paper for the CNRS IN2P3 Prospective 2020 focuses on realistic and timely situations of inflation in connection with the CMB, gravitational and particle physics, adding inter-disciplinarity and unification values within a strongly predictive physical approach. The formulation of inflation in the Ginsburg-Landau approach developed by de Vega and Sanchez [1] and by Boyanovsky, de Vega, Sanchez and Destri [2]-[4] clarifies and places inflation in the setting of the effective field theories of particle physics. In addition, it sets up a clean way to directly confront the inflationary predictions with the available and forthcoming CMB data and select a definitive model. All CMB + LSS data until now show how powerful is the Ginsburg-Landau effective theory of inflation in predicting observables in agreement with observations including the inflation energy scale and the inflaton potential, and which has much more to provide in the future. It paves the way to discoveries, new learning and understanding.
Vinicius Mikuni🇨🇭 · Florencia Canelli🇨🇭
In high energy physics, graph-based implementations have the advantage of treating the input data sets in a similar way as they are collected by collider experiments. To expand on this concept, we propose a graph neural network enhanced by attention mechanisms called ABCNet. To exemplify the advantages and flexibility of treating collider data as a point cloud, two physically motivated problems are investigated: quark-gluon discrimination and pileup reduction. The former is an event-by-event classification while the latter requires each reconstructed particle to receive a classification score. For both tasks ABCNet shows an improved performance compared to other algorithms available.
* 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.