HEP Phenomenology·hep-ph
22 papers—18 primary·4 cross-listed·reconstructed*
I give an overview on models that extend the Standard Model scalar sector by additional gauge singlets or multiplets. I discuss current constraints on such models, as well as possible signatures and discovery prospects at current and future colliders.
P. L. Cástulo (1) · J. J. Toscano (2) · E. S. Tututi (1) · ((1) Facultad de Ciencias Físico Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, (2) Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla)
A bound on the CPT-odd four vector coefficient that appears in Higgs sector of the Minimal Standard Model Extended (MSME) is presented. The analysis is based on the contributions arising from the sector in question to the anomalous dipole moment for leptons calculated at the one loop level, for which an analytical expression is obtained. The largest contribution of this Lorentz violating coefficient is on the lightest lepton, which results as a consequence of a strong non-decoupling effect. By using the experimental uncertainty of the electron anomalous dipole moment we predict that GeV.
Ekta Chaubey🇮🇹 · Mandeep Kaur🇮🇳 · Ambresh Shivaji🇮🇳
We present analytic results for all the Feynman integrals relevant for virtual corrections to decay. We use the method of differential equations to solve the master integrals while keeping the full dependence on the masses of all the particles including internal propagators. Due to the presence of four mass scales we encounter multiple square roots. We argue that all the occurring square roots can not be rationalized at the same time as a simultaneous rationalization brings us to integrals over manifolds. Hence we rationalize only three square roots simultaneously and construct suitable ansätze to obtain dlog-forms containing the square root, after obtaining an epsilon-factorised form for the differential equations. We present the alphabet and the analytic form of all the boundary constants that appear in the solutions of the differential equations. The results for master integrals are expressed in terms of Chen's iterated integrals with dlog one-forms.
Joshua Isaacson🇺🇸 · William I. Jay🇺🇸 · Alessandro Lovato🇺🇸 · Pedro A. N. Machado🇺🇸 · Noemi Rocco🇺🇸
We present a novel lepton-nucleus event generator: ACHILLES, A CHIcagoLand Lepton Event Simulator. The generator factorizes the primary interaction from the propagation of hadrons in the nucleus, which allows for a great deal of modularity, facilitating further improvements and interfaces with existing codes. We validate our generator against high quality electron-carbon scattering data in the quasielastic regime, including the recent CLAS/e4v reanalysis of existing data. We find good agreement in both inclusive and exclusive distributions. By varying the assumptions on the propagation of knocked out nucleons throughout the nucleus, we estimate a component of theoretical uncertainties. We also propose novel observables that will allow for further testing of lepton-nucleus scattering models. ACHILLES is readily extendable to generate neutrino-nucleus scattering events.
Koichi Hattori🇨🇳 · Kazunori Itakura🇯🇵
We investigate the axial Ward identity (AWI) for massive fermions in strong magnetic fields. The divergence of the axial-vector current is computed at finite temperature and/or density with the help of a relation between the polarization and anomaly diagrams in the effective (1+1) dimensions realized in the lowest Landau level (LLL). We discuss delicate interplay between the vacuum and medium contributions that determines patterns of the spectral flow in the adiabatic limit and, more generally, the diabatic chirality production rate. We also establish an explicit relation between the AWIs from the LLL approximation and from the familiar triangle diagrams in the naive perturbative series with respect to the coupling constant.
In this proceeding, I present the results of a recent global fit of an effective field theory of dark matter, performed using the Global and Modular Beyond-the-Standard Model Inference Tool (GAMBIT). A Dirac fermion dark matter candidate is assumed to interact only with Standard Model quarks and gluons, through a general set of operators up to mass dimension 7. The results provide a reasonably up-to-date summary of our knowledge of possible WIMP interactions.
Monal Kashav🇮🇳 · Surender Verma🇮🇳
The topological classification of one-loop Weinberg operator at dimension-5 leads to systematic categorization of one-loop neutrino mass models. All one-loop neutrino mass models must fall in one of these categories. Among these topological categories, loop extension of canonical seesaw scenarios is interesting in light of the current LHC run. Apart from one-loop contribution, these extensions result in dominant tree-level contribution to neutrino masses. The immediate remedy to obtain dominant one-loop contribution requires combination of flavor symmetries and enlarged field content. Alternatively, in this work, we propose a minimal way of realizing the topological structures with dominant one-loop contribution using modular variant of the permutation symmetries. In such a realization, no new fields are needed apart from those permitted by the topology itself. For the first time, we have realized one such topological Lorentz structure(T4-2-) pertaining to one-loop extension of Type-II seesaw using modular A symmetry. Here, modular weights play an important role in suppressing tree-level terms and stabilizing the particles running in the loop(, and ), thus, making them suitable dark matter candidates. In this work, we have explored the possibility of fermionic dark matter candidate where right-handed neutrino () is assumed to be lightest. We have, also, analyzed the compatibility of the model with neutrino oscillation data and obtained model predictions for effective Majorana mass and violation. Furthermore, the predictions on relic density of dark matter and its direct detection considering bound on lepton flavor violating process, have, also, been investigated.
Hariom Sogarwal🇮🇳 · Prashant Shukla🇮🇳
We present a study of coherent pion production in neutrino-nucleus interactions using the formalism based on partially conserved axial current theorem which connects the neutrino-nucleus cross section to the pion-nucleus elastic scattering cross section. Pion-nucleus elastic scattering cross section is calculated using Glauber model which takes three inputs, nuclear densities, pion-nucleon cross section and which is the ratio of real to imaginary part of forward scattering amplitude, for which the parametrizations are obtained from measured data. We calculate the differential and integrated cross sections for charge and neutral current coherent pion production in neutrino (anti-neutrino)-nucleus scattering for a range of nuclear targets from light to heavy materials such as lithium, carbon, hydrocarbon, oxygen, silicon, argon, iron and lead. The results of these cross section calculations are compared with the measured data and with the calculations from the Berger-Sehgal model and GENIE package. There is an excellent agreement between the calculated and measured cross sections with Glauber model. While GENIE and Berger-Sehgal model give a good description of the data in the lower energy range the present calculations describe the data in all energy ranges. Predictions are also made for upcoming experiments like INO and DUNE in the coherent region of neutrino cross section.
It is demonstrated that accounting for lepton flavor universality violating anomalies in meson decays via models implies a Landau pole problem. A family of models is proposed that resolve both issues simultaneously, fix the metastability of the Higgs and are predictive up to the Planck scale.
Nico Benincasa🇪🇪 · Luigi Delle Rose🇮🇹 · Kristjan Kannike🇪🇪 · Luca Marzola🇪🇪
The inert doublet model is a well-motivated extension of the Standard Model that contains a dark matter candidate and modifies the dynamics of the electroweak symmetry breaking. In order to detail its phenomenology, we perform a comprehensive study of cosmic phase transitions and gravitational wave signals implied by the framework, accounting for the latest results of collider experiments. We require the neutral inert scalar to constitute, at least, a subdominant part of the observed dark matter abundance. While most of the phase transitions proceed through a single step, we identify regions of the parameter space where the electroweak vacuum is reached after multiple phase transitions. The resulting gravitational wave spectrum is generally dominated by single-step transitions and, in part of the parameter space, falls within the reach of future gravitational wave detectors such as LISA, BBO or DECIGO. We find that direct detection experiments efficiently probe the part of parameter space associated with multi-step phase transitions, which remain unconstrained only in the Higgs resonance region testable with future monojet searches. The implications of the new determination of the boson mass are also discussed.
The detection of coherent elastic neutrino-nucleus scattering (CENS) opens new possibilities for neutrino physics within and beyond the Standard Model. Following the initial discovery in 2017, several experimental attempts have emerged allowing this reaction channel to be studied with the full repertoire of modern detection technologies. As one of several reactor experiments, CONUS aims for an observation with antineutrinos emitted from the powerful GW reactor of the nuclear power plant in Brokdorf (Germany). In particular, the application of ultra-low threshold, high-purity germanium detectors within a sophisticated shield design in close proximity to a nuclear reactor core represents an important step towards high-statistics neutrino detection with small-scale detectors. In addition to the conventional interaction, typical extensions of the Standard Model neutrino sector can be investigated with data provided from different neutrino sources and several target materials. Among these, new neutrino interactions as well as electromagnetic neutrino properties are of particular interest. This talk gives an overview of existing CENS results and highlights the advantage of using different neutrino sources and target materials. The example of CONUS is used to demonstrate the various capabilities of recent and future CENS measurements.
Yizhuang Liu🇵🇱 · Maciej A. Nowak🇵🇱 · Ismail Zahed🇺🇸
We derive a general formula for the replica partition function in the vacuum state, for a large class of interacting theories with fermions, with or without gauge fields, using the equal-time formulation on the light front. The result is used to analyze the spatial entanglement of interacting Dirac fermions in two-dimensional QCD. A particular attention is paid to the issues of infrared cut-off dependence and gauge invariance. The Renyi entropy for a single interval, is given by the rainbow dressed quark propagator to order . The contributions to order , are shown to follow from the off-diagonal and off mass-shell mesonic T-matrix, with no contribution to the central charge. The construction is then extended to mesonic states on the light front, and shown to probe the moments of the partonic PDFs for large light-front separations. In the vacuum and for small and large intervals, the spatial entanglement entropy following from the Renyi entropy, is shown to be in agreement with the Ryu-Takayanagi geometrical entropy, using a soft-wall AdS model of two-dimensional QCD.
Evgeny Andronov🇷🇺 · Magdalena Kuich🇵🇱 · Marek Gaździcki🇵🇱
Many new particles, mostly hadrons, are produced in high energy collisions between atomic nuclei. The most popular models describing the hadron production process are based on the creation, evolution and decay of resonances, strings or quark-gluon plasma. The validity of these models is under vivid discussion, and it seems that a common framework for this discussion is missing. Here we introduce the diagram of high energy nuclear collisions, where domains of the dominance of different hadron-production processes in the space of laboratory-controlled parameters, the collision energy and nuclear-mass number of colliding nuclei, are indicated. We argue, the recent experimental results locate boundaries between the domains, allowing for the first time to sketch an example diagram. Finally, we discuss the immediate implications for experimental measurements and model development following the sketch.
We derive the dependence of the leading-twist pion light-cone distribution amplitude (LCDA) on a parton momentum fraction by directly solving the dispersion relations for the moments with inputs from the operator product expansion (OPE) of the corresponding correlation function. It is noticed that these dispersion relations must be organized into those for the Gegenbauer coefficients first in order to avoid the ill-posed problem appearing in the conversion from the moments to the Gegenbauer coefficients. Given the values of various condensates in the OPE, we find that a solution for the pion LCDA, which is stable in the Gegenbauer expansion, exists. Moreover, the solution from summing contributions up to 18 Gegenbauer polynomials is smooth, and can be well approximated by a function proportional to with at the scale GeV. Turning off the condensates, we get the asymptotic form, independent of the scale , for the pion LCDA as expected. We then solve for the pion LCDA at a different scale GeV with the condensate inputs at this , and demonstrate that the result is consistent with the one obtained by evolving the Gegenbauer coefficients from GeV to 1.5 GeV. That is, our formalism is compatible with the QCD evolution. The strength of the above approach that goes beyond analyses limited to only the first few moments of a LCDA in conventional QCD sum rules is highlighted. The precision of our results can be improved systematically by including higher-order and higher-power terms in the OPE.
David E. Kaplan🇺🇸 · Andrea Mitridate🇺🇸 · Tanner Trickle🇺🇸
Pulsar Timing Arrays (PTAs) are exceptionally sensitive detectors in the frequency band . Ultralight dark matter (ULDM), with mass in the range , is one class of DM models known to generate signals in this frequency window. While purely gravitational signatures of ULDM have been studied previously, in this work we consider two signals in PTAs which arise in presence of direct couplings between ULDM and ordinary matter. These couplings induce variations in fundamental constants, i.e., particle masses and couplings. These variations can alter the moment of inertia of pulsars, inducing pulsar spin fluctuations via conservation of angular momentum, or induce apparent timing residuals due to reference clock shifts. By using mock data mimicking current PTA datasets, we show that PTA experiments outperform torsion balance and atomic clock constraints for ULDM coupled to electrons, muons, or gluons. In the case of coupling to quarks or photons, we find that PTAs and atomic clocks set similar constraints. Additionally, we discuss how future PTAs can further improve these constraints, and detail the unique properties of these signals relative to the previously studied effects of ULDM on PTAs.
Pedro Cal🇩🇪 · Jesse Thaler🇺🇸 · Wouter J. Waalewijn🇳🇱
Power counting is a systematic strategy for organizing collider observables and their associated theoretical calculations. In this paper, we use power counting to characterize a class of jet substructure observables called energy flow polynomials (EFPs). EFPs provide an overcomplete linear basis for infrared-and-collinear safe jet observables, but it is known that in practice, a small subset of EFPs is often sufficient for specific jet analysis tasks. By applying power counting arguments, we obtain linear relationships between EFPs that hold for quark and gluon jets to a specific order in the power counting. We test these relations in the parton shower generator Pythia, finding excellent agreement. Power counting allows us to truncate the basis of EFPs without affecting performance, which we corroborate through a study of quark-gluon tagging and regression.
Abhish Dev🇺🇸 · Gordan Krnjaic🇺🇸 · Pedro Machado🇺🇸 · Harikrishnan Ramani🇺🇸
If ultralight eV), bosonic dark matter couples to right handed neutrinos, active neutrino masses and mixing angles depend on the ambient dark matter density. When the neutrino Majorana mass, induced by the dark matter background, is small compared to the Dirac mass, neutrinos are "pseudo-Dirac" fermions that undergo oscillations between nearly degenerate active and sterile states. We present a complete cosmological history for such a scenario and find severe limits from a variety of terrestrial and cosmological observables. For scalar masses in the "fuzzy" dark matter regime ( eV), these limits exclude couplings of order , corresponding to Yukawa interactions comparable to the gravitational force between neutrinos and surpassing equivalent limits on time variation in scalar-induced electron and proton couplings.
Linda M. Carpenter🇺🇸 · Taylor Murphy🇺🇸 · Tim M. P. Tait🇺🇸
We study a renormalizable model of Dirac fermion dark matter (DM) that communicates with the Standard Model (SM) through a pair of mediators -- one scalar, one fermion -- in the representation of the SM gauge group . While such assignments preclude direct coupling of the dark matter to the Standard Model at tree level, we examine the many effective operators generated at one-loop order when the mediators are heavy, and find that they are often phenomenologically relevant. We reinterpret dijet and pair-produced resonance and searches at the Large Hadron Collider (LHC) in order to constrain the mediator sector, and we examine an array of DM constraints ranging from the observed relic density to indirect and direct searches for dark matter. Tree-level annihilation, available for DM masses starting at the TeV scale, is required in order to produce through freeze-out, but loops -- led by the dimension-five DM magnetic dipole moment -- are nonetheless able to produce signals large enough to be constrained, particularly by the XENON1T experiment. In some benchmarks, we find a fair amount of parameter space left open by experiment and compatible with freeze-out. In other scenarios, however, the open space is quite small, suggesting a need for further model-building and/or non-standard cosmologies.
V.I. Kukulin🇷🇺 · V.N. Pomerantsev🇷🇺 · O.A. Rubtsova🇷🇺 · M.N. Platonova🇷🇺 · I.T. Obukhovsky🇷🇺
The dibaryon concept for the nuclear force is presented, assuming that the main attraction between the nucleons at medium distances is determined by the -channel exchange of an intermediate six-quark (dibaryon) state. To construct the respective interaction model, a microscopic six-quark description of the system is used, in which symmetry aspects play a special role. It is shown that the interaction in all important partial waves can be described properly by a superposition of the long-range -channel one-pion exchange and the -channel exchange by an intermediate dibaryon. The developed model gives a good description of both elastic phase shifts and inelasticities of scattering in all , , and partial waves at energies from zero to 600 - 800 MeV and even higher.The parameters of the intermediate six-quark states corresponding to the best fit of scattering data are found to be consistent with the parameters of the known dibaryon resonances in those partial configurations where their existence has been experimentally confirmed. Predictions for new dibaryon states are given as well.
Anish Ghoshal🇵🇱 · Debangshu Mukherjee🇮🇳 · Massimiliano Rinaldi🇮🇹
In scale-invariant models of fundamental physics all mass scales are generated via spontaneous symmetry breaking. In this work, we study inflation in scale-invariant quadratic gravity, in which the Planck mass is generated classically by a scalar field, which evolves from an unstable fixed point to a stable one thus breaking scale-invariance. We investigate the dynamics by means of dynamical system standard techniques. By computing the spectral indices and comparing them with data, we put some constraints on the three dimensionless parameters of the theory. We show that certain regions of the parameter space will be within the range of future CMB missions like CMB-S4, LiteBIRD and STPol. The second half of the paper is dedicated to the analysis of inflationary first-order tensor perturbations and the calculation of the power spectrum of the gravitational waves. We comment on our results and compare them with the ones of mixed Starobinsky-Higgs inflation.
Holger Gies🇩🇪 · Dimitrios Gkiatas🇩🇪 · Luca Zambelli🇮🇹
We combine a recent construction of a BRST-invariant, nonlinear massive gauge fixing with the background field formalism. The resulting generating functional preserves background-field invariance as well as BRST invariance of the quantum field manifestly. The construction features BRST-invariant mass parameters for the quantum gauge and ghost fields. The formalism employs a background Nakanishi-Lautrup field which is part of the nonlinear gauge-fixing sector and thus should not affect observables. We verify this expectation by computing the one-loop effective action and the corresponding beta function of the gauge coupling as an example. The corresponding Schwinger functional generating connected correlation functions acquires additional one-particle reducible terms that vanish on shell. We also study off-shell one-loop contributions in order to explore the consequences of a nonlinear gauge fixing scheme involving a background Nakanishi-Lautrup field. As an application, we show that our formalism straightforwardly accommodates nonperturbative information about propagators in the Landau gauge in the form of the so-called decoupling solution. Using this nonperturbative input, we find evidence for the formation of a gluon condensate for sufficiently large coupling, whose scale is set by the BRST-invariant gluon mass parameter.
T. Zalialiutdinov🇷🇺 · D. Solovyev🇷🇺 · D. Chubukov🇷🇺 · S. Chekhovskoi🇷🇺 · L. Labzowsky🇷🇺
It is well-known that the 4-rotation in the 4-dimensional space-time is equivalent to the CPT-transformation (C is the charge conjugation, P is the space inversion and T is the time-reversal). The standard definition of the T-reversal includes the change of the sign of time variable and replacement of the initial state of the particle (system of particles) by the final state and vice versa. Since the time-reversal operation changes the state of a particle, the particle's wave function cannot be the eigenfunction of the corresponding operator with a certain eigenvalue, as in the case of space parity. Unlike the CPT-transformation, the separate P, T, or C transformations cannot be reduced to any 4-rotation. The extended Lorentz group incorporates all the separate C, P, or T transformations which do not bring the time axis out of the corresponding light cone. The latter restriction is included in the standard definition of the time-reversal. In the present communication, we ignore this restriction. This allows to introduce the "time arrow" operator and characterize every particle by the new quantum number - "time arrow" value. The wave functions of all particles are eigenfunctions of this operator with eigenvalues equal to "time arrow" values. The particles with the "time arrow" values opposite to the "time arrow" value in our universe form another universe (anti-universe). The existence of anti-universe can be confirmed, in principle, by laboratory (atomic) experiments. The anti-universe may be also considered as a candidate to the role of dark matter.
* 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.