HEP Phenomenology·hep-ph

Tue·Jul 20, 2021Tuesday·July 20, 2021

42 papers—26 primary·16 cross-listed·reconstructed*

01*
CP-Violation in a Composite 2-Higgs Doublet Model
Stefania De Curtis🇮🇹 · Stefano Moretti🇬🇧 · Ryo Nagai🇯🇵 · Kei Yagyu🇯🇵
We study CP-Violation (CPV) in a Composite 2-Higgs Doublet Model (C2HDM) based on the global symmetry breaking $S O (6) / [S O (4) \times S O (2)]$ , wherein the strong sector is modeled by a two-site moose structure. Non-trivial complex phases in the interactions involving fermions in both the elementary and strong sectors can induce CPV in the Higgs potential as well as the Yukawa coupling parameters. We compute both of the latter and analyse their dependence upon the aforementioned complex phases. Finally, we discuss physics observables which are distinctive of this model. Even in the simplest case with only one complex phase in the strong sector we can get significant CPV effects.
hep-phJHEP(2021)·10 citations
02*
Next-to-leading order corrections for $g g \to Z H$ with top quark mass dependence
Guoxing Wang🇨🇳 · Xiaofeng Xu🇨🇭 · Yongqi Xu🇨🇳 · Li Lin Yang🇨🇳
In this Letter, we present for the first time a calculation of the complete next-to-leading order corrections to the $g g \to Z H$ process. We use the method of small mass expansion to tackle the most challenging two-loop virtual amplitude, in which the top quark mass dependence is retained throughout the calculations. We show that our method provides reliable numeric results in all kinematic regions, and present phenomenological predictions for the total and differential cross sections at the Large Hadron Collider and its future upgrades. Our results are necessary ingredients towards reducing the theoretical uncertainties of the $pp \to Z H$ cross sections down to the percent-level, and provide important theoretical inputs for future precision experimental collider programs.
hep-phhep-exPLB(2022)·34 citations
03*
Exploring multi-Higgs models with softly broken large discrete symmetry groups
Ivo de Medeiros Varzielas🇵🇹 · Igor P. Ivanov🇨🇳 · Miguel Levy🇵🇹
We develop methods to study the scalar sector of multi-Higgs models with large discrete symmetry groups that are softly broken. While in the exact symmetry limit, the model has very few parameters and can be studied analytically, proliferation of quadratic couplings in the most general softly broken case makes the analysis cumbersome. We identify two sets of soft breaking terms which play different roles: those which preserve the symmetric vacuum expectation value alignment, and the remaining terms which shift it. Focusing on alignment preserving terms, we check which structural features of the symmetric parent model are conserved and which are modified. We find remarkable examples of structural features which are inherited from the parent symmetric model and which persist even when no exact symmetry is left. The general procedure is illustrated with the example of the three-Higgs-doublet model with the softly broken symmetry group $Σ (36)$ .
hep-phEPJC(2021)·18 citations
04*
Collective modes in anisotropic plasmas
Margaret E. Carrington🇨🇦 · Bailey M. Forster🇨🇦 · Sofiya Makar🇨🇦
We study collective modes in anisotropic plasmas of quarks and gluons using a quasi-particle picture and a hard loop approximation. We use a general class of anisotropic distribution functions, and we consider chirally asymmetric systems. We introduce a complete tensor basis to decompose the gluon polarization tensor into a set of nine scalar functions. We derive and solve the corresponding dispersion equations. Imaginary modes are particularly important because of their potential influence on plasma dynamics. We explore in detail their dependence on the chiral chemical potential and the parameters that characterise the anisotropy of the system. We show that our generalized distributions produce dispersion relations that are much richer in structure than those obtained with a simple one parameter deformation of an isotropic distribution. In addition, the size and domain of the imaginary solutions are enhanced, relative to those obtained with a one parameter deformation. Finally, we show that the influence of even a very small chiral chemical potential is significantly magnified when anisotropy is present.
hep-phnucl-thPRC(2021)·14 citations
05*
Asymmetric baryon capture by primordial black holes and baryon asymmetry of the universe
A. D. Dolgov🇷🇺 · N. A. Pozdnyakov🇷🇺
We have refined our previously suggested scenario of generation of the cosmological baryon asymmetry through an asymmetric capture of baryons and antibaryons by primordial block hole arXiv:2009.04361. It is found that in the limit of weak interactions of hypothetical heavy baryons with the primeval plasma the effect can be strongly enhanced and the observed magnitude of the asymmetry can be obtained for a wide range of the model parameters.
hep-phhep-thPRD(2021)·10 citations
06*
What can we learn from the total width of the Higgs boson?
Qing-Hong Cao🇨🇳 · Hao-Lin Li🇨🇳 · Ling-Xiao Xu🇨🇳 · Jiang-Hao Yu🇨🇳
As one of the key properties of the Higgs boson, the Higgs total width is sensitive to global profile of the Higgs boson couplings, and thus new physics would modify the Higgs width. We investigate the total width in various new physics models, including various scalar extension, composite Higgs models, and fraternal twin Higgs model. Typically the Higgs width is smaller than the standard model value due to mixture with other scalar if the Higgs is elementary, or curved Higgs field space for the composite Higgs. On the other hand, except the possible invisible decay mode, the enhanced Yukawa coupling in the two Higgs doublet model or the exotic fermion embeddings in the composite Higgs, could enhance the Higgs width greatly. The precision measurement of the Higgs total width at the high-luminosity LHC can be used to discriminate certain new physics models.
hep-phhep-exCPC(2023)·5 citations
07*
Probing gluon density fluctuations at large momentum transfer $∣ t ∣$ at HERA
Arjun Kumar🇮🇳
The information on the gluonic structure and its fluctuations is captured by the differential $∣ t ∣$ spectrum in diffractive events. The incoherent cross-section is sensitive to the fluctuations in the target wavefunction in such events. We investigate the incoherent $e p$ cross-section in $J / ψ$ photoproduction using the impact-parameter dependent dipole model. The spatial gluonic structure is modelled as hotspots of gluon density having substructure where this substructure is modelled as hotspots within hotspots. We find that three levels of the substructure provide a good description of all the data, available up to $∣ t ∣ = 30$ GeV $^{2}$ . We investigate these fluctuations in both the saturated and non-saturated dipole models and compare our predictions with the HERA Data.
hep-phSciPost Phys.Proc.(2022)·0 citations
08*
$B_{c} \to J / ψ$ helicity form factors and the $B_{c}^{+} \to J / ψ + (P, V, ℓ^{+} ν_{ℓ})$ decays
Wei Cheng🇨🇳 · Yi Zhang🇨🇳 · Long Zeng🇨🇳 · Hai-Bing Fu🇨🇳 · Xing-Gang Wu🇨🇳
In this paper, we calculate the $B_{c} \to J / ψ$ helicity form factors (HFFs) up to twist-4 accuracy by using the light-cone sum rules (LCSR) approach. After extrapolating those HFFs to the physically allowable $q^{2}$ region, we investigate the $B_{c}^{+}$ -meson two-body decays and semi-leptonic decays $B_{c}^{+} \to J / ψ + (P, V, ℓ^{+} ν_{ℓ})$ with $P / V$ stands for light pseudoscalar/vector meson, respectively. The branching fractions can be derived by using the CKM matrix element and the $B_{c}$ lifetime from the Particle Data Group, and we obtain $B (B_{c}^{+} \to J / ψ π^{+}) = (0.13 6_{- 0.002}^{+ 0.002}) %$ , $B (B_{c}^{+} \to J / ψ K^{+}) = (0.01 0_{- 0.000}^{+ 0.000}) %$ , $B (B_{c}^{+} \to J / ψ ρ^{+}) = (0.76 8_{- 0.033}^{+ 0.029}) %$ , $B (B_{c}^{+} \to J / ψ K^{*+}) = (0.04 3_{- 0.001}^{+ 0.001}) %$ , $B (B_{c}^{+} \to J / ψ μ^{+} ν_{μ}) = (2.80 2_{- 0.675}^{+ 0.526}) %$ and $B (B_{c}^{+} \to J / ψ τ^{+} ν_{τ}) = (0.55 9_{- 0.170}^{+ 0.131}) %$ . We then obtain $R_{π^{+} / μ^{+} ν_{μ}} = 0.04 8_{- 0.012}^{+ 0.009}$ and $R_{K^{+} / π^{+}} = 0.07 5_{- 0.005}^{+ 0.005}$ , which agree with the LHCb measured value within $1 σ$ -error. We also obtain $R_{J / ψ} = 0.19 9_{- 0.077}^{+ 0.060}$ , which like other theoretical predictions, is consistent with the LHCb measured value within $2 σ$ -error. Those imply that the HFFs under the LCSR approach are also applicable to the $B_{c}^{+}$ meson two-body decays and semi-leptonic decays $B_{c}^{+} \to J / ψ + (P, V, ℓ^{+} ν_{ℓ})$ , and the HFFs obtained by using LCSR in a new way implies that there may be new physics in the $B_{c} \to J / ψ ℓ^{+} ν_{ℓ}$ semi-leptonic decays.
hep-phCPC(2022)·7 citations
09*
Symmetries, partners and thresholds: the case of the $X_{b}$
Pablo G. Ortega🇪🇸 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸
The discovery of the $X (3872)$ meant the revival of the heavy meson spectroscopy beyond naive $q q ˉ$ structures. Once that the $S U (3)$ scheme, which was very useful in the dawn of the quark models, does not work for these states, one has to use new symmetries, like Heavy Quark Spin Symmetry (HQSS) and Heavy Flavor Symmetry (HFS), to look for new states. However, at the energy regions where these new states appear, new factors are involved and it is not straightforward to relate the predictions of the symmetries with the data. In this work, we present a critical analysis of this problem and show, in a coupled-channels model, how the relative position of the bare $Q Q ˉ$ states with respect to meson-meson thresholds and the coupling with other channels modulate the strength of the interaction and, hence, modify the structure of the predicted states. We found a possible candidate to the $X (3872)$ partner at $10599$ MeV $/ c^{2}$ .
hep-phSymmetry(2021)·6 citations
10*
On the Transfer of Polarization from the Initial to the Final Proton in the Elastic Process $e p \to e p$
M.V. Galynskii🇧🇾
The $Q^{2}$ dependence of the ratio of the cross sections with and without proton spin flip, as well as the polarization asymmetry in the process $e p \to e p$ has been numerically analyzed using the results of JLab polarization experiments on the measurements of the ratio of the Sachs form factors in the $e p \to e p$ process. The calculations have been made for the case where the initial (at rest) and final protons are fully polarized and have a common spin quantization axis, which coincides with the direction of motion of the final proton. The longitudinal polarization transfer to the proton has been calculated in the case of the partially polarized initial proton for a kinematics used in the experiment reported in [A. Liyanage et al. (SANE Collaboration), Phys. Rev. C 101, 035206 (2020)], where the double spin asymmetry was measured in the $e p \to e p$ process. A noticeable sensitivity of the polarization transfer to the proton to the form of the $Q^{2}$ dependence of the ratio $μ_{p} G_{E} / G_{M}$ has been found. This sensitivity may be used to conduct a new independent experiment to measure this dependence in the $e p \to e p$ process. A criterion to assess the reliability of measurements of the ratio of Sachs form factors using the Rosenbluth technique has been proposed and used to analyze the results of two experiments.
hep-phhep-exJETP Lett.(2021)·4 citations
11*
Efficient approach to low scale Peccei-Quinn symmetry breaking without domain wall problem
Pei-Hong Gu🇨🇳
We propose an efficient mechanism to realize an invisible axion from a low scale Peccei-Quinn symmetry breaking. Our basic model only contains a gauge boson, an up-type vector-like quark, two Higgs doublets and two Higgs singlets besides the standard model fermions and gauge bosons. The physical Peccei-Quinn global symmetry is a result of two independent global symmetries connected by the new gauge symmetry. Anyone of these two global symmetries only acts on either the right-handed top quark or the left-handed new quark so that it can avoid the domain wall problem. Thanks to the electroweak and new gauge interactions, the Higgs doublet for the top quark mass generation and the Higgs singlet for the new quark mass generation can only contribute a tiny fraction in the axion. The axion decay constant can be largely enhanced by a factor composed of the vacuum expectation values of the four Higgs scalars.
hep-ph0 citations
12*
The Future of Solar Neutrinos
G. D. Orebi Gann🇺🇸 · K. Zuber🇩🇪 · D. Bemmerer🇩🇪 · A. Serenelli🇪🇸
In this article we review the current state of the field of solar neutrinos, including flavour oscillations, non-standard effects, solar models, cross section measurements, and the broad experimental program thus motivated and enabled. We discuss the historical discoveries that contributed to current knowledge, and define critical open questions to be addressed in the next decade. We discuss the state of the art of standard solar models, including uncertainties and problems related to the solar composition, and review experimental and model solar neutrino fluxes, including future prospects. We review the state of the art of the nuclear reaction data relevant for solar fusion in the proton-proton chain and carbon-nitrogen-oxygen cycle. Finally, we review the current and future experimental program that can address outstanding questions in this field.
hep-phastro-ph.SRhep-exnucl-exAnn.Rev.Nucl.Part.Sci.(2021)·69 citations
13*
Hidden charm pentaquark states in a diquark model
Pan-Pan Shi🇨🇳 · Fei Huang🇨🇳 · Wen-Ling Wang🇨🇳
The mass spectrum of hidden charm pentaquark states composed of two diquarks and an antiquark are calculated by use of an effective Hamiltonian which includes explicitly the spin, color, and flavor dependent interactions. The results show that the $P_{c} (4312)^{+}$ and $P_{c} (4440)^{+}$ states could be explained as hidden charm pentaquark states with isospin and spin-parity $I J^{P} = 1/2 (3/ 2^{-})$ , the $P_{c} (4457)^{+}$ state could be explained as a hidden charm pentaquark state with $I J^{P} = 1/2 (5/ 2^{-})$ , and the $P_{cs} (4459)^{+}$ state could be explained as a hidden charm pentaquark state with $I J^{P} = 0 (1/ 2^{-})$ or $0 (3/ 2^{-})$ . Predications for the masses of other possible pentaquark states are also given, and the possible decay channels of these hidden charm pentaquark states are discussed.
hep-phnucl-thEPJA(2021)·37 citations
14*
On the Geometric Phase and Majorana Neutrinos
Antonio Capolupo🇮🇹 · Salvatore Marco Giampaolo🇭🇷 · Beatrix C. Hiesmayr🇦🇹 · Gaetano Lambiase🇮🇹 · Aniello Quaranta🇮🇹
We analyze the geometric phase for neutrinos and we demonstrate that the geometric invariants associated to transitions between different neutrino flavors, for Majorana neutrinos, can depend on the representation of the mixing matrix and then are sensitive to the nature of neutrinos. The dependence of geometric invariants on the Majorana phase cannot be eliminated by a charged lepton rephasing transformation. By considering kinematic and geometric approach we also demonstrate that the Majorana phase is relevant in the projective Hilbert space. Geometric invariants can in principle be used as tools to distinguish between Dirac and Majorana neutrinos.
hep-phhep-thJ.Phys.G(2023)·15 citations
15*
Sauter-Schwinger effect for colliding laser pulses
Christian Kohlfürst🇩🇪 · Naser Ahmadiniaz🇩🇪 · Johannes Oertel🇩🇪 · Ralf Schützhold🇩🇪
Via a combination of analytical and numerical methods, we study electron-positron pair creation by the electromagnetic field $A (t, r) = [f (c t - x) + f (c t + x)] e_{y}$ of two colliding laser pulses. Employing a generalized WKB approach, we find that the pair creation rate along the symmetry plane $x = 0$ (where one would expect the maximum contribution) displays the same exponential dependence as for a purely time-dependent electric field $A (t) = 2 f (c t) e_{y}$ . The pre-factor in front of this exponential does also contain corrections due to focusing or de-focusing effects induced by the spatially inhomogeneous magnetic field. We compare our analytical results to numerical simulations using the Dirac-Heisenberg-Wigner method and find good agreement.
hep-phhep-thPRL(2022)·53 citations
16*
Flavor Symmetries in the Yukawa Sector of Non-Supersymmetric SO(10): Numerical Fits Using Renormalization Group Running
Tommy Ohlsson🇸🇪 · Marcus Pernow🇸🇪
We consider a class of $SO (10)$ models with flavor symmetries in the Yukawa sector and investigate their viability by performing numerical fits to the fermion masses and mixing parameters. The fitting procedure involves a top-down approach in which we solve the renormalization group equations from the scale of grand unification down to the electroweak scale. This allows the intermediate scale right-handed neutrinos and scalar triplet, involved in the type I and II seesaw mechanisms, to be integrated out at their corresponding mass scales, leading to a correct renormalization group running. The result is that, of the 14 models considered, only two are able to fit the known data well. Both these two models correspond to $Z_{2}$ symmetries. In addition to being able to fit the fermion masses and mixing parameters, they provide predictions for the sum of light neutrino masses and the effective neutrinoless double beta decay mass parameter, which are both within current observational bounds.
hep-phJHEP(2021)·6 citations
17*
Radiative transitions of charmonium states in the covariant confined quark model
Gurjav Ganbold🇷🇺 · Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Valery E. Lyubovitskij🇩🇪
We have studied the dominant radiative transitions of the charmonium $S$ -and $P$ -wave states within the covariant confined quark model. The gauge invariant leading-order transition amplitudes have been expressed by using either the conventional Lorentz structures, or the helicity amplitudes, where it was effective. The renormalization couplings of the charmonium states have been strictly fixed by the compositeness conditions that excludes the constituent degrees of freedom from the space of physical states. We use the basic model parameters for the constituent c-quark mass $m_{c} = 1.80$ GeV and the global infrared cutoff $λ = 0.181$ GeV. We additionally introduce only one adjustable parameter $ϱ > 0$ common for the charmonium states $η_{c} (^{1} S_{0})$ , $J / ψ (^{3} S_{1})$ , $χ_{c 0} (^{3} P_{0})$ , $χ_{c 1} (^{3} P_{1})$ , $h_{c} (^{1} P_{1})$ , and $χ_{c 2} (^{3} P_{2})$ to describe the quark distribution inside the hadron. This parameter describes the ratio between the charmonium size and its physical mass. The optimal value $ϱ = 0.485$ has been fixed by fitting the latest data for the partial widths of the one-photon radiative decays of the triplet $χ_{c J} (^{3} P_{J}), J = {0, 1, 2}$ . Then, we calculate corresponding fractional widths for states $J / ψ (^{3} S_{1})$ and $h_{c} (^{1} P_{1})$ . Estimated results are in good agreement with the latest data. By using the fraction data from PDG2020 and our estimated partial decay width for $h_{c} (^{1} P_{1})$ we recalculate the theoretical full width $Γ_{h_{c}}^{theor} ≃ (0.57 \pm 0.12)$ MeV in comparison with latest data $Γ_{h_{c}}^{exp} ≃ (0.7 \pm 0.4)$ MeV. We also repeated our calculations by gradually decreasing the global cutoff parameter and revealed that the results do not change for any $λ < 0.181$ GeV up to the deconfinement limit.
hep-phPRD(2021)·18 citations
18*
Hydrodynamical attractor and thermal particle production in heavy-ion collision
Lakshmi J. Naik🇮🇳 · Sunil Jaiswal🇮🇳 · K. Sreelakshmi🇮🇳 · Amaresh Jaiswal🇮🇳 · V. Sreekanth🇮🇳
Study of thermal particle production is crucial to understand the space-time evolution of the fireball produced in high energy heavy-ion collisions. We consider thermal particle production within the framework of relativistic viscous hydrodynamics and employ recently obtained analytical solutions of higher-order viscous hydrodynamics with longitudinal Bjorken expansion to calculate the spectra of dileptons and photons. Using these analytical solutions, we constrain the allowed initial states by demanding positivity and reality of energy density throughout the evolution. Further, we compute thermal particle spectra and study the particle yield in context of hydrodynamic attractors. We find that, of all allowed solutions, the evolution corresponding to attractor solution leads to maximum production of thermal particles.
hep-phhep-thnucl-th11 citations
19*
The role of proton-antiproton regeneration in the late stages of heavy-ion collisions
Oscar Garcia-Montero🇩🇪 · Jan Staudenmaier🇩🇪 · Anna Schäfer🇩🇪 · Juan M. Torres-Rincon🇩🇪 · Hannah Elfner🇩🇪
We investigate the long-standing question of the effect of proton-antiproton annihilation on the (anti-)proton yield, while respecting detailed balance for the 5-body back-reaction for the first time in a full microscopic description of the late stages of heavy-ion collisions. This is achieved by employing a stochastic collision criterion in a hadronic transport approach (SMASH), which allows to treat arbitrary multi-particle reactions. It is used to account for the regeneration of (anti-)protons via $5 π \to p p ˉ$ . Our results show that a back-reaction happens for a fraction of 15-20\% of all annihilations. Within a viscous hybrid approach Au+Au/Pb+Pb collisions from $s_{N N} = 17.3$ GeV $- 5.02$ TeV are investigated and the quoted fraction is independent of the beam energy or centrality of the collision. Taking the back-reaction into account results in regeneration of half of the (anti-)proton yield that is lost due to annihilations at midrapidity. We also find that, concerning the multiplicities, treating the back-reaction as a chain of 2-body reactions is equivalent to a single 5-to-2 reaction.
hep-phnucl-thPRC(2022)·29 citations
20*
Analysis of the nonleptonic two-body decays of the $Λ$ hyperon
Mikhail A. Ivanov🇷🇺 · Jürgen G. Körner🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Zhomart Tyulemissov🇷🇺
We systematically study two-body nonleptonic decays of light lambda hyperon $Λ \to p π^{-} (n π^{0})$ with account for both short- and long-distance effects. The short-distance effects are induced by five topologies of external and internal weak $W^{\pm}$ exchange, while long-distance effects are saturated by an inclusion of the so-called pole diagrams with intermediate $\frac{1}{2}^{+}$ and $\frac{1}{2}^{-}$ baryon resonances. The contributions from $\frac{1}{2}^{+}$ resonances are calculated straightforwardly by account for nucleon and $Σ$ baryons whereas the contributions from $\frac{1}{2}^{-}$ resonances are calculated by using the well-known soft-pion theorem in the current-algebra approach. It allows one to express the parity-violating $S$ -wave amplitude in terms of parity-conserving matrix elements. From our previous analysis of heavy baryons we know that short-distance effects induced by internal topologies are not suppressed in comparison with external $W$ -exchange diagram and must be included for description of data. Here, in the case of $Λ$ decays we found that the contribution of external and internal $W$ -exchange diagrams is sizably suppressed, e.g., by one order of magnitude in comparison with data, which are known with quite good accuracy. Pole diagrams play the major role to get consistency with experiment.
hep-phPRD(2021)·5 citations
21*
A viable U(1) extended Standard Model with a massive Z' invoking the Stueckelberg mechanism
Radhika Vinze🇮🇳 · Sreerup Raychaudhuri🇮🇳
We make a careful re-examination of the possibility that, in a U(1) extension of the Standard Model, the extra Z' boson may acquire a mass from a Stueckelberg-type scalar. The model, when all issues of theoretical consistency are taken into account, contains several attractive new features, including a high degree of predictability.
hep-phhep-th5 citations
22*
Singlet Scalars as Dark Matter and the Muon g-2 Anomaly
Bastián Díaz Sáez🇩🇪 · Karim Ghorbani🇮🇷
We explore a simple model containing two singlet scalars as dark matter supplemented with a vector-like lepton. Evading collider and dark matter constraints, the model is able to accommodate the correct dark matter relic abundance and the muon g-2 anomaly when the masses of the three new fields are around 100 GeV and the values of the minimum amount of required couplings are order one.
hep-phPLB(2021)·18 citations
23*
Probing the $B + L$ violation process with the observation of cosmic magnetic field
Yuefeng Di🇨🇳 · Jialong Wang🇨🇳 · Ligong Bian🇨🇳 · Rong-Gen Cai🇨🇳 · Jing Liu🇨🇳
We investigate the $B + L$ violation process by performing three-dimensional lattice simulations in an electroweak theory with first-order phase transition and the electroweak sphaleron decay. The simulation results indicate that the Chern-Simons number changes along with the helical magnetic field production when the sphaleron decay occurs. Our study suggests that, for the electroweak phase transition with nucleation rate being smaller than $\sim O (10)$ , the helical magnetic field with the fractional magnetic helicity $ϵ_{M} \leq 0.2$ can be probed by Cherenkov Telescope Array through the intergalactic magnetic field measurements. Based on our numerical results, we suggest a method to probe the baryon asymmetry generation of the Universe, which is a general consequence of the electroweak sphaleron process, through the astronomical observation of the corresponding helical magnetic field.
hep-phastro-ph.COastro-ph.HEhep-lat1 citation
24*
Cosmological Particle Production and Pairwise Hotspots on the CMB
Jeong Han Kim🇰🇷 · Soubhik Kumar🇺🇸 · Adam Martin🇺🇸 · Yuhsin Tsai🇺🇸
Heavy particles with masses much bigger than the inflationary Hubble scale $H_{*}$ , can get non-adiabatically pair produced during inflation through their couplings to the inflaton. If such couplings give rise to time-dependent masses for the heavy particles, then following their production, the heavy particles modify the curvature perturbation around their locations in a time-dependent and scale non-invariant manner. This results into a non-trivial spatial profile of the curvature perturbation that is preserved on superhorizon scales and eventually generates localized hot or cold spots on the CMB. We explore this phenomenon by studying the inflationary production of heavy scalars and derive the final temperature profile of the spots on the CMB by taking into account the subhorizon evolution, focusing in particular on the parameter space where pairwise hot spots (PHS) arise. When the heavy scalar has an $O (1)$ coupling to the inflaton, we show that for an idealized situation where the dominant background to the PHS signal comes from the standard CMB fluctuations themselves, a simple position space search based on applying a temperature cut, can be sensitive to heavy particle masses $M_{0} / H_{*} \sim O (100)$ . The corresponding PHS signal also modifies the CMB power spectra and bispectra, although the corrections are below (outside) the sensitivity of current measurements (searches).
hep-phastro-ph.COJHEP(2021)·20 citations
25*
The Simplest and Most Predictive Model of Muon $g - 2$ and Thermal Dark Matter
Ian Holst🇺🇸 · Dan Hooper🇺🇸 · Gordan Krnjaic🇺🇸
The long-standing $4.2 σ$ muon $g - 2$ anomaly may be the result of a new particle species which could also couple to dark matter and mediate its annihilations in the early universe. In models where both muons and dark matter carry equal charges under a $U (1)_{L_{μ} - L_{τ}}$ gauge symmetry, the corresponding $Z^{'}$ can both resolve the observed $g - 2$ anomaly and yield an acceptable dark matter relic abundance, relying on annihilations which take place through the $Z^{'}$ resonance. Once the value of $(g - 2)_{μ}$ and the dark matter abundance are each fixed, there is very little remaining freedom in this model, making it highly predictive. We provide a comprehensive analysis of this scenario, identifying a viable range of dark matter masses between approximately 10 and 100 MeV, which falls entirely within the projected sensitivity of several accelerator-based experiments, including NA62, NA64 $μ$ , $M^{3}$ , and DUNE. Furthermore, portions of this mass range predict contributions to $Δ N_{eff}$ which could ameliorate the tension between early and late time measurements of the Hubble constant, and which could be tested by Stage 4 CMB experiments.
hep-phastro-ph.COhep-exPRL(2022)·54 citations
26*
Di-lepton Rapidity Distribution in Drell-Yan Production to Third Order in QCD
Xuan Chen🇨🇭 · Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Tong-Zhi Yang🇨🇭 · Hua Xing Zhu🇨🇳
We compute for the first time the lepton-pair rapidity distribution in the photon-mediated Drell-Yan process to next-to-next-to-next-to-leading order (N $^{3}$ LO) in QCD. The calculation is based on the qT-subtraction method, suitably extended to this order for quark-antiquark initiated Born processes. Our results display sizeable QCD corrections at N $^{3}$ LO over the full rapidity region and provide a fully independent confirmation of the recent results for the total Drell-Yan cross section at this order.
hep-phPRL(2022)·114 citations
27*
Odd-parity stability of black holes in Einstein-Aether gravity
Shinji Tsujikawa🇯🇵 · Chao Zhang🇺🇸 · Xiang Zhao🇺🇸 · Anzhong Wang🇺🇸
In Einstein-Aether theory, we study the stability of black holes against odd-parity perturbations on a spherically symmetric and static background. For odd-parity modes, there are two dynamical degrees of freedom arising from the tensor gravitational sector and Aether vector field. We derive general conditions under which neither ghosts nor Laplacian instabilities are present for these dynamical fields. We apply these results to concrete black hole solutions known in the literature and show that some of those solutions can be excluded by the violation of stability conditions. The exact Schwarzschild solution present for $c_{13} = c_{14} = 0$ , where $c_{i}$ 's are the four coupling constants of the theory with $c_{ij} = c_{i} + c_{j}$ , is prone to Laplacian instabilities along the angular direction throughout the horizon exterior. However, we find that the odd-parity instability of high radial and angular momentum modes is absent for black hole solutions with $c_{13} = c_{4} = 0$ and $c_{1} \geq 0$ .
↳ gr-qcastro-ph.GAhep-phhep-thPRD(2021)·17 citations
28*
Simulating Quantum Mechanics with a $θ$ -term and an 't Hooft Anomaly on a Synthetic Dimension
Jiayu Shen🇺🇸 · Di Luo🇺🇸 · Chenxi Huang🇺🇸 · Bryan K. Clark🇺🇸 · Aida X. El-Khadra🇺🇸 · Bryce Gadway🇺🇸 · Patrick Draper🇺🇸
A topological $θ$ -term in gauge theories, including quantum chromodynamics in 3+1 dimensions, gives rise to a sign problem that makes classical Monte Carlo simulations impractical. Quantum simulations are not subject to such sign problems and are a promising approach to studying these theories in the future. In the near term, it is interesting to study simpler models that retain some of the physical phenomena of interest and their implementation on quantum hardware. For example, dimensionally-reducing gauge theories on small spatial tori produces quantum mechanical models which, despite being relatively simple to solve, retain interesting vacuum and symmetry structures from the parent gauge theories. Here we consider quantum mechanical particle-on-a-circle models, related by dimensional reduction to the 1+1d Schwinger model, that possess a $θ$ -term and realize an 't Hooft anomaly or global inconsistency at $θ = π$ . These models also exhibit the related phenomena of spontaneous symmetry breaking and instanton-anti-instanton interference in real time. We propose an experimental scheme for the real-time simulation of a particle on a circle with a $θ$ -term and a $Z_{n}$ potential using a synthetic dimension encoded in a Rydberg atom. Simulating the Rydberg atom with realistic experimental parameters, we demonstrate that the essential physics can be well-captured by the experiment, with expected behavior in the tunneling rate as a function of $θ$ . Similar phenomena and observables can also arise in more complex quantum mechanical models connected to higher-dimensional nonabelian gauge theories by dimensional reduction.
↳ quant-phhep-lathep-phhep-th+1PRD(2022)·8 citations
29*
ERLC (Twin LC) and LHC/FCC Based eA Colliders
A. N. Akay🇹🇷 · B. Dagli🇹🇷 · B. Ketenoglu🇹🇷 · S. Sultansoy🇹🇷
Construction of the ERLC (twin LC) collider tangential to LHC or FCC will give opportunity to realize eA collisions at multi-TeV center-of-mass energies. Luminosity estimations show that values comparable with that of ERL60 based eA colliders are achievable while center of mass energies are essentially higher. Certainly, proposed eA colliders have great potential for clarifying QCD basics and nuclear structure.
↳ physics.acc-phhep-exhep-phnucl-ex+11 citation
30*
Hydrodynamic description of the baryon-charged quark-gluon plasma
Lipei Du (Ohio State U.)🇺🇸
One of the primary goals of nuclear physics is studying the phase diagram of Quantum Chromodynamics, where a hypothetical critical point serves as a landmark. A systematic model-data comparison of heavy-ion collisions at center-of-mass energies between 1 and 100 GeV per nucleon is essential for locating the critical point and the phase boundary between the deconfined quark-gluon plasma and the confined hadron resonance gas. At these energies the net baryon density of the system can be high and critical fluctuations can become essential in the presence of the critical point. Simulating their dynamical evolution thus becomes an indispensable part of theoretical modeling. In this thesis we first present the (3+1)-dimensional relativistic hydrodynamic code BEShydro, which solves the equations of motion of second-order Denicol-Niemi-Molnar-Rischke theory, including bulk and shear viscous components as well as baryon diffusion current. We then study the effects caused by the baryon diffusion on the longitudinal dynamics and on the phase diagram trajectories of fluid cells at different space-time rapidities of the system, and how they are affected by critical dynamics near the critical point. We finally explore the evolution of non-hydrodynamic slow processes describing long wavelength critical fluctuations near the critical point, by extending the conventional hydrodynamic description by coupling it to additional explicitly evolving slow modes, and their back-reaction to the bulk matter properties.
↳ nucl-thhep-phnucl-ex5 citations
31*
Charming synergies: the role of charm-threshold studies in the search for physics beyond the Standard Model
Guy Wilkinson🇬🇧
Measurements performed with pairs of charm mesons produced at threshold from the decay of the $ψ (3770)$ resonance are of great value in flavour physics. The quantum correlation that exists between the two mesons allows unique access to strong-phase information, which is essential input to flavour-physics studies conducted in other environments. An excellent example from the BESIII collaboration is a recent determination of the strong-phase difference between $D^{0}$ and $D ˉ^{0}$ mesons in the decay $D^{0} \to K_{S}^{0} π^{+} π^{-}$ , which has enabled recent measurements to be performed of the $C P$ -violating phase $γ$ and $D^{0} - D ˉ^{0}$ oscillations by the LHCb experiment at CERN. These $ψ (3770)$ data, and also those collected just above the thresholds for $D_{s}^{+}$ and $Λ_{c}^{+}$ production, can also be exploited in many other ways that are of benefit to flavour-physics studies. These synergies are reviewed, and the need for larger threshold data samples in the near future is emphasised.
↳ hep-exhep-phSci.Bull.(2021)·11 citations
32*
Constraining the swiss-cheese IR-fixed point cosmology with cosmic expansion
Ayan Mitra🇰🇿 · Vasilios Zarikas🇰🇿 · Alfio Bonanno🇮🇹 · Michael Good🇰🇿 · Ertan Güdekli🇹🇷
In a recent work, it has been proposed that the recent cosmic passage to a cosmic acceleration era is the result of the existence of small anti-gravity sources in each galaxy and clusters of galaxies. In particular, a swiss-cheese cosmology model which relativistically integrates the contribution of all these anti-gravity sources on galactic scale has been constructed assuming the presence of an infrared fixed point for a scale dependent cosmological constant. The derived cosmological expansion provides explanation for both the fine tuning and the coincidence problem. The present work relaxes the previous assumption on the running of the cosmological constant and allows for a generic scaling around the infrared fixed point. Our analysis reveals in order to produce a cosmic evolution consistent with the best $Λ$ CDM model, the IR-running of the cosmological constant is consistent with the presence of an IR-fixed point.
↳ gr-qcastro-ph.COhep-phhep-thUniverse(2021)·3 citations
33*
Science with the TianQin Observatory: Preliminary Results on Stochastic Gravitational-Wave Background
Zheng-Cheng Liang🇨🇳 · Yi-Ming Hu🇨🇳 · Yun Jiang🇨🇳 · Jun Cheng🇨🇳 · Jian-dong Zhang🇨🇳 · Jianwei Mei🇨🇳
In this work, we study the prospect of detecting the stochastic gravitational-wave background with the TianQin Observatory. We consider sources of both astrophysical-origin and cosmological-origin, including stellar-mass binary black holes, binary neutron stars, Galactic white dwarves, inflation, first-order phase transitions, and cosmic defects. For the detector configurations, we consider TianQin, TianQin I+II, and TianQin + LISA. We study the detectability of stochastic gravitational-wave backgrounds with both the cross correlation and null channel methods, and present the corresponding power-law integrated sensitivity curves. We introduce the definition of the "joint foreground" with a network of detectors. With the joint foreground, the number of resolved double white dwarves in the Galaxy will be increased by 5 $-$ 22\% compared with a simple combination of individual detectors. The astrophysical background is expected to be detectable with a signal-to-noise ratio of 100 after 5 years of operation and dominated by the extragalactic double white dwarves. On the other hand, due to the uncertain nature of underlying models, we can only estimate the detection capability of the cosmological background for specific cases.
↳ astro-ph.COgr-qchep-phPRD(2022)·104 citations
34*
Transport away your problems: Calibrating stochastic simulations with optimal transport
Chris Pollard🇬🇧 · Philipp Windischhofer🇬🇧
Stochastic simulators are an indispensable tool in many branches of science. Often based on first principles, they deliver a series of samples whose distribution implicitly defines a probability measure to describe the phenomena of interest. However, the fidelity of these simulators is not always sufficient for all scientific purposes, necessitating the construction of ad-hoc corrections to "calibrate" the simulation and ensure that its output is a faithful representation of reality. In this paper, we leverage methods from transportation theory to construct such corrections in a systematic way. We use a neural network to compute minimal modifications to the individual samples produced by the simulator such that the resulting distribution becomes properly calibrated. We illustrate the method and its benefits in the context of experimental particle physics, where the need for calibrated stochastic simulators is particularly pronounced.
↳ physics.data-anhep-phstat.MLNucl.Instrum.Meth.A(2022)·18 citations
35*
Topological axion electrodynamics and 4-group symmetry
Yoshimasa Hidaka🇯🇵 · Muneto Nitta🇯🇵 · Ryo Yokokura🇯🇵
We study higher-form symmetries and a higher group in the low energy limit of a $(3 + 1)$ -dimensional axion electrodynamics with a massive axion and a massive photon. A topological field theory describing topological excitations with the axion-photon coupling, which we call a topological axion electrodynamics, is obtained in the low energy limit. Higher-form symmetries of the topological axion electrodynamics are specified by equations of motion and Bianchi identities. We find that there are induced anyons on the intersections of symmetry generators. By a link of worldlines of the anyons, we show that the worldvolume of an axionic domain wall is topologically ordered. We further specify the underlying mathematical structure elegantly describing all salient features of the theory to be a 4-group.
↳ hep-thcond-mat.str-elhep-phPLB(2021)·56 citations
36*
Unpolarized gluon distribution in the nucleon from lattice quantum chromodynamics
Tanjib Khan🇺🇸 · Raza Sabbir Sufian🇺🇸 · Joseph Karpie🇺🇸 · Christopher J. Monahan🇺🇸 · Colin Egerer🇺🇸 · Bálint Joó🇺🇸 · Wayne Morris🇺🇸 · Kostas Orginos🇺🇸 · Anatoly Radyushkin🇺🇸 · David G. Richards🇺🇸 · Eloy Romero🇺🇸 · Savvas Zafeiropoulos🇫🇷
In this study, we present a determination of the unpolarized gluon Ioffe-time distribution in the nucleon from a first principles lattice quantum chromodynamics calculation. We carry out the lattice calculation on a $3 2^{3} \times 64$ ensemble with a pion mass of $358$ MeV and lattice spacing of $0.094$ fm. We construct the nucleon interpolating fields using the distillation technique, flow the gauge fields using the gradient flow, and solve the summed generalized eigenvalue problem to determine the glounic matrix elements. Combining these techniques allows us to provide a statistically well-controlled Ioffe-time distribution and unpolarized gluon PDF. We obtain the flow time independent reduced Ioffe-time pseudo-distribution, and calculate the light-cone Ioffe-time distribution and unpolarized gluon distribution function in the $MS$ scheme at $μ = 2$ GeV, neglecting the mixing of the gluon operator with the quark singlet sector. Finally, we compare our results to phenomenological determinations.
↳ hep-lathep-exhep-phnucl-ex+1PRD(2021)·80 citations
37*
Neural Conditional Reweighting
Benjamin Nachman🇺🇸 · Jesse Thaler🇺🇸
There is a growing use of neural network classifiers as unbinned, high-dimensional (and variable-dimensional) reweighting functions. To date, the focus has been on marginal reweighting, where a subset of features are used for reweighting while all other features are integrated over. There are some situations, though, where it is preferable to condition on auxiliary features instead of marginalizing over them. In this paper, we introduce neural conditional reweighting, which extends neural marginal reweighting to the conditional case. This approach is particularly relevant in high-energy physics experiments for reweighting detector effects conditioned on particle-level truth information. We leverage a custom loss function that not only allows us to achieve neural conditional reweighting through a single training procedure, but also yields sensible interpolation even in the presence of phase space holes. As a specific example, we apply neural conditional reweighting to the energy response of high-energy jets, which could be used to improve the modeling of physics objects in parametrized fast simulation packages.
↳ physics.data-anhep-exhep-phPRD(2022)·22 citations
38*
Heavy Flavor and Jet Studies for the Future Electron-Ion Collider to Explore the Hadronization Process
Xuan Li🇺🇸
Heavy flavor production at the future Electron-Ion Collider (EIC) will allow us to precisely determine the quark/gluon fragmentation processes in vacuum and the nuclear medium especially within the poorly constrained kinematic region. Heavy flavor hadron and jet reconstruction with the recent EIC detector design have been studies in simulation. Results of corresponding physics projections such as the flavor dependent hadron nuclear modification factor $R_{e A}$ in electron+nucleus collisions will be shown. The statistical precision obtained by these proposed heavy flavor measurements for the future EIC provides a strong discriminating power in separating different theoretical predictions.
↳ nucl-exhep-exhep-phnucl-thSciPost Phys.Proc.(2022)·6 citations
39*
A Cosmological Constant That is Too Small
Mehmet Demirtas🇺🇸 · Manki Kim🇺🇸 · Liam McAllister🇺🇸 · Jakob Moritz🇺🇸 · Andres Rios-Tascon🇺🇸
We construct a vacuum of string theory in which the magnitude of the vacuum energy is $< 1 0^{- 123}$ in Planck units. Regrettably, the sign of the vacuum energy is negative, and some supersymmetry remains unbroken.
↳ hep-thgr-qchep-phPRL(2022)·79 citations
40*
Dim but not entirely dark: Extracting the Galactic Center Excess' source-count distribution with neural nets
Florian List🇦🇺 · Nicholas L. Rodd🇨🇭 · Geraint F. Lewis🇦🇺
The two leading hypotheses for the Galactic Center Excess (GCE) in the $Fermi$ data are an unresolved population of faint millisecond pulsars (MSPs) and dark-matter (DM) annihilation. The dichotomy between these explanations is typically reflected by modeling them as two separate emission components. However, point-sources (PSs) such as MSPs become statistically degenerate with smooth Poisson emission in the ultra-faint limit (formally where each source is expected to contribute much less than one photon on average), leading to an ambiguity that can render questions such as whether the emission is PS-like or Poissonian in nature ill-defined. We present a conceptually new approach that describes the PS and Poisson emission in a unified manner and only afterwards derives constraints on the Poissonian component from the so obtained results. For the implementation of this approach, we leverage deep learning techniques, centered around a neural network-based method for histogram regression that expresses uncertainties in terms of quantiles. We demonstrate that our method is robust against a number of systematics that have plagued previous approaches, in particular DM / PS misattribution. In the $Fermi$ data, we find a faint GCE described by a median source-count distribution (SCD) peaked at a flux of $\sim 4 \times 1 0^{- 11} counts cm^{- 2} s^{- 1}$ (corresponding to $\sim 3 - 4$ expected counts per PS), which would require $N \sim O (1 0^{4})$ sources to explain the entire excess (median value $N = 29,300$ across the sky). Although faint, this SCD allows us to derive the constraint $η_{P} \leq 66%$ for the Poissonian fraction of the GCE flux $η_{P}$ at 95% confidence, suggesting that a substantial amount of the GCE flux is due to PSs.
↳ astro-ph.HEastro-ph.COastro-ph.IMcs.LG+1PRD(2021)·49 citations
41*
Relativistic meson spectra on ion-trap quantum simulators
Johannes Knaute🇩🇪 · Philipp Hauke🇮🇹
The recent rapid experimental advancement in the engineering of quantum many-body systems opens the avenue to controlled studies of fundamental physics problems via digital or analog quantum simulations. Here, we systematically analyze the capability of analog ion traps to explore relativistic meson spectra on current devices. We focus on the E_8 quantum field theory regime, which arises due to longitudinal perturbations at the critical point of the transverse-field Ising model. As we show through exact numerics, for sufficiently strong long-range suppression in experimentally accessible spin chain models, absorption spectroscopy allows for the identification of the low-lying meson excitations with a good degree of accuracy even for small system sizes. Our proposal thus opens a way for probing salient features of quantum many-body systems reminiscent of meson properties in high-energy physics.
↳ cond-mat.str-elcond-mat.quant-gashep-phhep-th+1PRA(2022)·15 citations
42*
Free-streaming and Coupled Dark Radiation Isocurvature Perturbations: Constraints and Application to the Hubble Tension
Subhajit Ghosh🇺🇸 · Soubhik Kumar🇺🇸 · Yuhsin Tsai🇺🇸
Dark radiation (DR) appears as a new physics candidate in various scenarios beyond the Standard Model. While it is often assumed that perturbations in DR are adiabatic, they can easily have an isocurvature component if more than one field was present during inflation, and whose decay products did not all thermalize with each other. By implementing the appropriate isocurvature initial conditions (IC), we derive the constraints on both uncorrelated and correlated DR density isocurvature perturbations from the full Planck 2018 data alone, and also in combination with other cosmological data sets. Our study on free-streaming DR (FDR) updates and generalizes the existing bound on neutrino density isocurvature perturbations by including a varying number of relativistic degrees of freedom, and for coupled DR (CDR) isocurvature, we derive the first bound. We also show that for CDR qualitatively new physical effects arise compared to FDR. One such effect is that for isocurvature IC, FDR gives rise to larger CMB anisotropies compared to CDR -- contrary to the adiabatic case. More generally, we find that a blue-tilt of DR isocurvature spectrum is preferred. This gives rise to a larger value of the Hubble constant $H_{0}$ compared to the standard $Λ$ CDM+ $Δ N_{eff}$ cosmology with adiabatic spectra and relaxes the $H_{0}$ tension.
↳ astro-ph.COhep-phJCAP(2022)·44 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.