HEP Phenomenology·hep-ph
29 papers—22 primary·7 cross-listed·reconstructed*
We discuss recent higher order calculations to properties of mesons. This includes next-to-next-to-leading order corrections to nonleptonic and next-to-next-to-next-to-leading order corrections to semileptonic meson decays. The latter is important in connection to the determination of the CKM matrix element . We also discuss next-to-next-to-leading order corrections to the width difference in the neutral meson system.
Higgs boson pair production plays an important role in the determination of the Higgs boson self coupling. The predictions based on next-to-leading order corrections show a large dependence on the renormalization scheme of the top quark mass, which requires a next-to-next-to-leading order calculation. We discuss the current status and show first results of the three-loop virtual corrections.
Hidetoshi Taya🇯🇵 · Asanosuke Jinno🇯🇵 · Masakiyo Kitazawa🇯🇵 · Yasushi Nara🇯🇵
We investigate the volume and lifetime of the high baryon-density matter created in heavy-ion collisions and estimate the optimal collision-energy range to realize the high baryon-density region over a large spacetime volume. We simulate central collisions of gold ions for the center-of-mass energy per nucleon pair with a microscopic transport model JAM. We discover that the optimal range is around , where a baryon density exceeding three times the normal nuclear density is realized with a substantially large spacetime volume. Higher and lower energies are disfavored due to short lifetime and low density, respectively. We also point out that event-by-event fluctuations of the spacetime density profile are large, indicating the importance of the event selection in the experimental analysis.
Kyu Jung Bae🇰🇷 · Jinn-Ouk Gong🇰🇷 · Dong-Won Jung🇰🇷 · Kang Young Lee🇰🇷 · Chaehyun Yu🇰🇷 · Chan Beom Park🇰🇷
We present the phenomenology of the charged Higgs boson appearing in a fermionic dark matter model mediated by an additional scalar doublet. In order to couple the dark matter fermion to the scalar doublet, we introduce a U(1) gauge symmetry, which is spontaneously broken at electroweak symmetry breaking, resulting in a massive gauge boson. Since is generically light, the model is subject to strong constraints from electroweak precision observables. As a result, the charged Higgs boson mass allowed by current experimental bounds is typically light in this model, 110 GeV 170 GeV. Such a light charged Higgs boson will be produced mainly through top-quark decays at the LHC. Additionally, depending on the mass of the additional neutral Higgs boson and the dark gauge boson , the direct production channels and can become sizable. We investigate the corresponding signal processes at the LHC to assess the discovery potential for . Current ATLAS and CMS searches for light charged Higgs bosons already impose further constraints on the model. We also discuss the implications of dark matter in relation to the charged Higgs boson phenomenology.
Peter W. Graham🇺🇸 · Harikrishnan Ramani🇺🇸 · Samuel S. Y. Wong🇺🇸
While much supersymmetric weakly interacting massive particle (WIMP) parameter space has been ruled out, one remaining important candidate is Higgsino dark matter. The Higgsino can naturally realize the "inelastic dark matter" scenario, where the scattering off a nucleus occurs between two nearly-degenerate states, making it invisible to WIMP direct detection experiments if the splitting is too large to be excited. It was realized that a "luminous dark matter" detection process, where the Higgsino upscatters in the Earth and subsequently decays into a photon in a large neutrino detector, offers the best sensitivity to such a scenario. We consider the possibility of adding a large volume of a heavy element, such as Pb or U, around the detector. We also consider the presence of U and Th in the Earth itself, and the effect of an enhanced high-velocity tail of the dark matter distribution due to the presence of the Large Magellanic Cloud. These effects can significantly improve the sensitivity of detectors such as JUNO, SNO+, KamLAND, and Borexino, potentially making it possible in the future to cover much of the remaining parameter space for this classic supersymmetric WIMP dark matter.
Pooja Jakhad🇮🇳 · Juhi Oudichhya🇮🇳 · Ajay Kumar Rai🇮🇳
Significant efforts have been made in recent years to measure the properties of charmed baryons. In this work, we study the and baryons in the relativistic flux tube model with a quark-diquark picture of a baryon. The modified Regge relation between mass and angular momentum is used to predict the spin-average masses. The spin-dependent interactions are also included to compute the spin-dependent splitting. We calculate the masses of states belonging to the -wave and -wave of and baryons, which are not yet detected experimentally. Our mass predictions can offer valuable insights to experimental facilities in their search to discover the higher excited states of and baryons.
Sarif Khan🇩🇪 · Jinsu Kim🇨🇳 · Jongkuk Kim🇰🇷 · Pyungwon Ko🇰🇷
We study multi-component dark matter scenarios and the Galactic 511 keV -ray emission line signal in the framework of a local, dark extension of the Standard Model. A light vector dark matter particle associated with the dark may decay and annihilate to electron-positron pairs. The produced positrons may in turn form positroniums that subsequently annihilate to two photons, accounting for the observed line signal of the Galactic 511 keV -ray emission. Three scenarios are investigated. First, we consider the minimal extension where a dark gauge boson and a dark Higgs boson are newly introduced to the particle content. As a second scenario, we consider WIMP-type dark matter with the introduction of an extra dark fermion which, in addition to the dark gauge boson, may contribute to the dark matter relic abundance. It is thus a multi-component dark matter scenario with a UV-complete dark symmetry. In particular, the vector dark matter may account for a small fraction of the total dark matter relic abundance. Finally, we consider the scenario where the dark matter particles are of the FIMP-type. In this case, both the light vector and fermion dark matter particles may be produced via the freeze-in and super-WIMP mechanisms. Considering theoretical and observational constraints, we explore the allowed parameter space where the Galactic 511 keV -ray line signal and the dark matter relic can both be explained. We also discuss possible observational signatures.
Mohamed El Arebi Gadja🇩🇿 · Yazid Delenda🇩🇿 · Lamine Khodja🇩🇿
This paper presents a comprehensive study of top quark phenomenology within the Non-Commutative Standard Model. We calculate non-commutative corrections to the squared amplitudes for top quark pair production, as well as for single top quark production via the -channel and -channel, while noting that the -channel remains unaffected by non-commutative geometry. Utilizing MadGraph5_aMC@NLO, we determine total cross-sections at various center-of-mass energies and examine differential distributions in transverse momentum and rapidity at leading order in both the strong coupling and the non-commutative parameter . For single top production in the -channel, a matching technique is employed to extend the validity of the distribution to low values through resummation. We also compare the non-commutative corrections with higher-order QCD corrections obtained at NLO using MCFM and at NNLO from existing literature. Our findings reveal significant deviations arising from non-commutative geometry at high energies, providing insights into potential new physics at energy scales accessible by current and future colliders.
Anja Alfano🇬🇧 · Nick Evans🇬🇧
In gauge theories, the running of the anomalous dimension of a fermion bilinear operator is believed to lead to chiral symmetry breaking when gamma=1. Naively using perturbative results to judge when gamma=1 leads to the possibility of large dynamically generated mass hierarchies in models with both two index symmetric representation and fundamental representation fermions. In this paper we study a holographic model of this physics to predict the separation in scales in the meson spectrum. We study SU(Nc) theories at different Nc with one flavour of two index symmetric representation as a function of the number of fundamental fermion flavours NfF. The largest hierarchy we find is for Nc=7 and NfF=22 where the rho mesons made of the two different representations are separated in scale by a factor of 13. For general Nc the hierarchy can be made greater than 7 by tuning NfF. We display the hierarchy as a function of NfF and investigate the quark mass dependence. These predictions do depend on the extrapolation of gamma from the perturbative regime - even in a pessimistic scenario a distinct gap can be achieved.
Hui-Hua Zhong🇨🇳 · Ming-Sheng Liu🇨🇳 · Ru-Hui Ni🇨🇳 · Mu-Yang Chen🇨🇳 · Xian-Hui Zhong · Qiang Zhao🇨🇳
In this work we systematically study both the mass spectra and strong decays of the nucleon and resonances up to the shell within a unified quark model framework with chiral dynamics. In this framework we achieve a good description of the strong decay properties of the well-established nucleon and resonances. Meanwhile, the mass reversal between as the first radial excitation state and the -wave nucleon resonances can be explained. We show that the three-body spin-orbit potential arising from the one-gluon exchange can cause a large configuration mixing between and , and is also responsible for the large splitting between and . Some of these baryon resonances turn to weakly couple to the , , , and channels, which may answer the question why they have not been established in these channels via the and scatterings. It shows that these ``missing resonances" may have large potentials to be established in the final state due to their large decay rates into either the or -wave nucleon resonances via the pionic decays. Further experimental search for their signals in charmonium decays at BESIII is thus strongly recommended.
Eric Braaten🇺🇸 · Roberto Bruschini🇺🇸
The Born-Oppenheimer potentials for QCD with light quarks include adjoint-hadron potentials that are repulsive at short distances and heavy-hadron-pair potentials that approach thresholds at large distances. The adjoint-hadron potentials must connect smoothly to the heavy-hadron-pair potentials at intermediate distances. We identify exotic hidden-heavy hadrons as bound states and resonances in adjoint-hadron potentials that cross below a heavy-hadron-pair threshold before approaching it. This explains why many exotic hidden-charm and hidden-bottom hadrons have energies near heavy-hadron-pair thresholds. The remarkable properties of some exotic hidden-heavy mesons can be explained by fine tunings of adjoint-meson energies in QCD.
Qi Xin🇨🇳 · Zhi-Gang Wang🇨🇳
We systematically study the 1D charmonium spin-triplet (with the ) and spin-singlet (with the ) via the QCD sum rules in comparison with the recent experimental results. The predicted mass supports identifying the as the , the value is consistent with the reported observation of the , the prediction supports identifying the as the . Additionally, we estimate the unobserved state lies at , and suggest detection prospects in the future. More experimental data will help us to unravel the mass spectrum of the charmonium states near the open-charm thresholds.
We present a procedure g5anchor to anchor in the definition of a Dirac trace with in Dimensional Regularization (DR) in Feynman diagrams for the Standard Model, based on a recent revision of the works by Kreimer, Gottlieb and Donohue. For each closed fermion chain with an odd number of primitive (i.e.~not-yet-clearly-defined) in a given Feynman diagram, g5anchor returns a definite set of anchor points for , in terms of pairs of ordered fermion propagators; at each of these anchor points a fixed expression in terms of the Levi-Civita tensor and elementary Dirac matrices will be inserted together with a sign determined by anticommutatively shifting all from their original places (dictated by the Feynman rules) to this anchor point. The defining expressions for the cyclic -odd Dirac traces in DR associated with closed fermion chains in amplitudes, or more generally squared amplitudes, thus follow from this procedure, where the Levi-Civita tensors are not necessarily treated strictly in 4-dimensions. We propose utilizing this definition in practical perturbative calculations in the Standard Model at least to two-loop orders with the current implementation. Certain limitations and modifications of the KKS and/or the Kreimer scheme are addressed, as well as the possible caveats with g5anchor.
Ke Yang🇨🇳 · Tianbo Liu🇨🇳 · Peng Sun🇨🇳 · Yuxiang Zhao🇨🇳 · Bo-Qiang Ma🇨🇳
We report on the first global analysis of transverse momentum dependent helicity distributions of the proton. The analysis is performed at next-to-leading order with the evolution factor at next-to-next-to-leading-logarithmic accuracy. Nonzero signals are determined for up and down quarks and their -integrated polarization are consistent with analyses in collinear factorization, while the distributions of other flavors are loosely constrained by existing data. With increasing transverse momentum, quarks at large become less polarized while those at small become more polarized.
Yu Zhang🇨🇳
We propose a new channel to search for millicharged particles at the future Super Tau Charm Facility (STCF) via mono- signature. For the first time, we compute the mono- signal events at the future STCF due to millicharged particle production, as well as due to standard model irreducible/reducible backgrounds. By utilizing the assumed 20 ab luminosity for each running energy with GeV, 4 GeV and 7 GeV, we derive the corresponding upper limits on millicharge, respectively. Via mono- searches at the future STCF with GeV, the upper limits on millicharge can be improved than ArgoNeuT when the mass of millicharged particle is less than about 500 MeV, but are not very competitive compared to a latest derivation from a past BEBC experiment and a new SENSEI experiment. Regardless, the mono- searches could be an important complement to investigate the invisible particles, such as dark matter.
Simon Badger🇮🇹 · Heribertus Bayu Hartanto🇰🇷 · Zihao Wu🇨🇳 · Yang Zhang🇨🇳 · Simone Zoia🇨🇭
We present the two-loop helicity amplitudes contributing to the next-to-next-to-leading order QCD predictions for W-boson production in association with two photons at the Large Hadron Collider. We derived compact analytic expressions for the two-loop amplitudes in the leading colour limit, and provide numerical results for the subleading colour contributions. We employ a compact system of integration-by-part identities provided by the NeatIBP package, allowing for an efficient computation of the rational coefficients of the scattering amplitudes over finite fields.
Rouzbeh Allahverdi🇺🇸 · Adrian Thompson🇺🇸 · Mohammadreza Zakeri🇺🇸
Rare processes in laboratory and within astrophysical environments can be highly sensitive probes of baryon-number violating interactions at the TeV scale. We demonstrate the power of neutron stars to constrain baryon number violation by considering a minimal extension of the standard model involving a TeV-mass scalar mediator and a GeV scale Majorana fermion . We find that a mass-loss process in binary pulsar systems via and the subsequent scattering places stringent constraints on the model parameter space. These limits will become much stronger, due to the possibility of decays at the tree level, if the neutron star equation of state is hyperonic. We compare these constraints with ongoing and future collider experiments, oscillations, and dinucleon decay searches at future large-scale neutrino experiments, finding that the binary pulsars bounds on couplings are significantly tighter for specific flavor combinations.
Gongjun Choi🇺🇸 · Wenqi Ke🇺🇸 · Keith A. Olive🇺🇸
The expected improvements in the precision of inflationary physics observables including the scalar spectral index and the tensor-to-scalar ratio will reveal more than just the viability of a particular model of inflation. In the presence of a curvaton field , supposedly dead models of inflation can be resurrected as these observables are affected by curvaton perturbations. For currently successful models, improved constraints will enable us to constrain the properties of extra decaying scalar degrees of freedom produced during inflation. In this work, we demonstrate these diverse uses of a curvaton field with the most recent constraints on () and two exemplary inflation models, the Starobinsky model, and a model of new inflation. Our analysis invokes three free parameters: the curvaton mass , its decay rate the reheating temperature produced by inflaton decays. We systematically analyze possible post-inflationary era scenarios of a curvaton field. By projecting the most recent CMB data on () into this parameter space, we can either set constraints on the curvaton parameters from successful models of inflation (so that the success is not spoiled) or determine the parameters which are able to save a model for which is predicted to be below the experimental data. We emphasize that the initial value of produced during inflation is determined from a stochastic approach and thus not a free parameter in our analysis. We also investigate the production of local non-Gaussianity and apply current CMB constraints to the parameter space. Intriguingly, we find that a large value of of can be produced for both of the two representative inflation models.
Yuan-Zhen Li🇨🇳 · Jiang-Hao Yu🇨🇳
The primordial neutrino asymmetry leaves profound imprints on the evolution history of the universe, which can be constrained by cosmological observations, including Big Bang Nucleosynthesis (BBN), Cosmic Microwave Background (CMB), and Large-Scale Structure (LSS). We present comprehensive analysis on implications and constraints of the primordial neutrino asymmetry, based on a precise treatment of neutrino decoupling by solving the complete (anti)neutrino quantum kinetic equations in the Closed-Time-Path formalism. { Assuming the same primordial asymmetry for all neutrino flavors,} the effective number of neutrinos and (anti)neutrino spectral distortions are calculated, and we find that the non-instantaneous decoupling correction is given by . Then we perform the state-of-the-art calculation for the abundance of light elements including (anti)neutrino spectral distortions, which indicate a positive asymmetry from EMPRESS data. The implications of the neutrino asymmetry for the CMB and LSS are studied in detail, and we find that the Baryon Acoustic Oscillations (BAO) are also significantly affected by \xi_\nu = 0.024 \pm 0.012$, which provides constraints on UV models capable of producing large asymmetries.
Melissa van Beekveld🇳🇱 · Mrinal Dasgupta🇬🇧 · Basem Kamal El-Menoufi🇦🇺 · Jack Helliwell🇬🇧 · Pier Francesco Monni🇨🇭 · Gavin P. Salam🇬🇧
We formulate a collinear partonic shower algorithm that achieves next-to-single-logarithmic (NSL, ) accuracy for collinear-sensitive non-singlet fragmentation observables. This entails the development of an algorithm for nesting triple-collinear splitting functions. It also involves the inclusion of the one-loop double-collinear corrections, through a -dependent NLO-accurate effective branching probability, using a formula that can be applied more generally also to future full showers with splitting kernels. The specific NLO branching probability is calculated in two ways, one based on slicing, the other using a subtraction approach based on recent analytical calculations. We close with demonstrations of the shower's accuracy for non-singlet partonic fragmentation functions and the energy spectrum of small- quark jets. This work represents an important conceptual step towards general NNLL accuracy in parton showers.
Joseph Bramante🇨🇦 · Melissa D. Diamond🇨🇦 · J. Leo Kim🇨🇦
We demonstrate a new technique to search for dark compact objects. When dark matter comprising a dark compact object interacts with photons, the compact object can disperse light traveling though it. As these objects pass between Earth and a distant star, they act as "lampshades" that dim the star. We examine how dimming effects from clumps of dark matter in the Galaxy could be searched for in microlensing surveys, which measure the brightness of stars as a function of time. Using the EROS-2 and OGLE surveys, we show that a dimming analysis of existing data can be used to constrain dark sectors, and could be used to discover dark matter in compact objects.
Nathaniel Craig🇺🇸 · Emanuele Gendy🇩🇪 · Jessica N. Howard🇺🇸
We study the theory of a scalar in the fundamental representation of the internal supergroup . Remarkably, for its tree-level mass does not receive quantum corrections at one loop from either self-coupling or interactions with gauge bosons and fermions. This property comes at the price of introducing both degrees of freedom with wrong statistics and with wrong sign kinetic terms. We detail a method to break down to its bosonic subgroup through a Higgs-like mechanism, allowing for the partial decoupling of the dangerous modes, and study the associated vacuum structure up to one loop.
Anson Hook🇺🇸 · Clayton Ristow🇺🇸
We study (multi) fermion - monopole bound states, many of which are the states that dyons adiabatically transition into as fermions become light. The properties of these bound states depend critically on the UV symmetries preserved by the fermion mass terms, their relative size, and the value of . Depending on the relative size of the mass terms and the value of , the bound states can undergo phase transitions as well as transition from being stable to unstable. In some simple situations, the bound state solution can be related to the Witten effect of another theory with fewer fermions and larger gauge coupling. These bound states are a result of mass terms and symmetry breaking boundary conditions at the monopole core and, consequently, these bound states do not necessarily have definite quantum numbers under accidental IR symmetries. Additionally, they have binding energies that are times the fermion mass and bound state radii of order their inverse mass. As the massless limit is approached, the bound state radii approach infinity, and they become new asymptotic states with odd quantum numbers giving a dynamical understanding to the origin of semitons.
Within the framework of symmetric teleparallel -gravity for a connection defined in the non-coincidence gauge we derive the Wheeler-DeWitt equation of quantum cosmology. Because the gravitational field equation in -gravity admits a minisuperspace description the Wheeler-DeWitt equation is a single inhomogeneous partial differential equations. We assume the power-law model and with the application of linear quantum observables we calculate the wavefunction of the universe. Finally, we investigate the effects of the quantum correction terms in the semi-classical limit.
We examine the framework of relativistic spin-hydrodynamics in the context of electron hydrodynamics in graphene. We develop a spin-hydrodynamic model for a (2 + 1)-dimensional system of fermions under the condition of small spin polarization. Our analysis confirms that thermal vorticity, which satisfies the global equilibrium condition, is also a solution to the spin-hydrodynamic equations. Additionally, we calculate the magnetization of the system in global equilibrium and introduce a novel phenomenon - thermovortical magnetization - resulting from thermal vorticity, which can be experimentally observed in graphene.
As one of the predictions of perturbative QCD, the effect of color transparency has been the focus of attention in the community studying modifications of hadrons in nuclear medium for several decades. The search for this effect in reactions involving heavy nuclei can be complicated by uncertainties in nuclear characteristics (nucleon density distributions and wave functions), which can affect the interpretation of experiments. In this work, we consider the reaction at GeV/c caused by hard elastic scattering, in which these uncertainties are actually reduced to the behavior of the deuteron wave function at large momenta. It is shown that for transverse momenta of the spectator neutron GeV/c the choice of the deuteron wave function cannot affect the identification of the color transparency effect. A simple method for studying color transparency in collisions is also suggested based on the identification of quasi-free interactions.
V. A. Zaytsev🇩🇪 · V. A. Yerokhin🇩🇪 · C. H. Keitel🇩🇪 · N. S. Oreshkina🇩🇪
Self-energy and vacuum polarization effects in quantum electrodynamics (QED) are calculated for the supercritical Coulomb field, where Dirac energy levels become embedded in the negative-energy continuum. In this regime, the quantum vacuum becomes unstable, resulting in spontaneous electron-positron pair creation. By calculating the imaginary part of the QED correction, we gain access to an unexplored channel of vacuum instability: radiative spontaneous pair creation. Our results show that this radiative channel is greatly enhanced in the vicinity of the threshold of the supercritical regime, providing evidence for nonperturbative effects with respect to the fine-structure constant . We therefore conjecture that the total probability of spontaneous pair creation could differ significantly from the predictions of Dirac theory, especially near the supercritical threshold.
Andreas Ekström🇸🇪 · Lucas Platter🇺🇸
We use Bayesian statistics to infer the breakdown scale of pionless effective field theory in its standard power counting and with renormalization of observables carried out using the power-divergence subtraction scheme and cutoff regularization. We condition our inference on predictions of the total neutron-proton scattering cross section up next-to-next-to leading order. We quantify a median breakdown scale of approximately 1.4. The 68% degree of belief interval is . This result confirms the canonical expectation that the pion mass is a relevant scale in low-energy nuclear physics.
Jian-Feng He🇨🇳 · Chengjie Fu🇨🇳 · Kai-Ge Zhang🇨🇳 · Zong-Kuan Guo🇨🇳
An axion-like spectator during inflation can trigger a tachyonic instability which amplifies the modes of one of the helicities of the gauge field, resulting in the production of parity-violating gravitational waves (GWs). In this paper we investigate the impact of the coupling of the gauge field to gravity on the production of GWs. We find that such a coupling introduces a multiplicative factor to the tachyonic mass, which effectively enhances the amplitude of the gauge field modes. Produced GWs are expected to be observed by future space-based GW detectors. Additionally, we find that the strong backreaction due to particle production leads to multiple peaks in the energy spectrum of GWs.
* 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.