Fri·Jul 30, 2021Friday·July 30, 2021

1. 01*

   The photon content of the proton in the CT18 global analysis

   Keping Xie🇺🇸 · T. J. Hobbs🇺🇸 · Tie-Jiun Hou🇨🇳 · Carl Schmidt🇺🇸 · Mengshi Yan🇨🇳 · C.-P. Yuan🇺🇸

   Recently, two photon PDF sets based on implementations of the LUX ansatz into the CT18 global analysis were released. In CT18lux, the photon PDF is calculated directly using the LUX master formula for all scales, $\mu$. In an alternative realization, CT18qed, the photon PDF is initialized at the starting scale, ${\mu }_0$, using the LUX formulation and evolved to higher scales $\mu (>{\mu }_0)$ with a combined QED+QCD kernel at $\mathcal{O}(\alpha ),\mathcal{O}(\alpha {\alpha }_s)$ and $\mathcal{O}({\alpha }^2)$. In the small-$x$ region, the photon PDF uncertainty is mainly induced by the quark and gluon PDFs, through the perturbative DIS structure functions. In comparison, the large-$x$ photon uncertainty comes from various low-energy, nonperturbative contributions, including variations of the inelastic structure functions in the resonance and continuum regions, higher-twist and target-mass corrections, and elastic electromagnetic form factors of the proton. We take the production of doubly-charged Higgs pairs, $(H^{++}{H}^{--})$, as an example of scenarios beyond the Standard Model to illustrate the phenomenological implications of these photon PDFs at the LHC.

   hep-phhep-exnucl-thSciPost Phys.Proc.(2022)·8 citations
2. 02*

   Longitudinally polarized ZZ scattering at the Muon Collider

   Tianyi Yang🇨🇳 · Sitian Qian🇨🇳 · Zhe Guan🇨🇳 · Congqiao Li🇨🇳 · Fanqiang Meng🇨🇳 · Jie Xiao🇨🇳 · Meng Lu🇨🇳 · Qiang Li🇨🇳

   Measuring longitudinally polarized vector boson scattering in, e.g., the ZZ channel is a promising way to investigate the unitarization scheme from the Higgs and possible new physics beyond the Standard Model. However, at the LHC, it demands the end of the HL-LHC lifetime luminosity, 3000/fb, and advanced data analysis technique to reach the discovery threshold due to its small production rates. Instead, there could be great potential for future colliders. In this paper, we perform a Monte Carlo study and examine the projected sensitivity of longitudinally polarized ZZ scattering at a TeV scale muon collider. We conduct studies at 14 TeV and 6 TeV muon colliders respectively and find that a 5 standard deviation discovery can be achieved at a 14 TeV muon collider, with 3000/fb of data collected. While a 6 TeV muon collider can already surpass HL-LHC, reaching 2 standard deviations with around 4000/fb of data. The effect from lepton isolation and detector granularity is also discussed, which may be more obvious at higher energy muon colliders, as the leptons from longitudinally polarized Z decays tend to be closer.

   hep-phhep-exPRD(2021)·10 citations
3. 03*

   New opportunities for axion dark matter searches in nonstandard cosmological models

   Paola Arias🇨🇱 · Nicolás Bernal🇨🇴 · Dimitrios Karamitros🇵🇱 · Carlos Maldonado🇨🇱 · Leszek Roszkowski🇵🇱 · Moira Venegas🇨🇱

   We study axion dark matter production from a misalignment mechanism in scenarios featuring a general nonstandard cosmology. Before the onset of Big Bang nucleosynthesis, the energy density of the universe is dominated by a particle field $\varphi$ described by a general equation of state $\omega$. The ensuing enhancement of the Hubble expansion rate decreases the temperature at which axions start to oscillate, opening this way the possibility for axions heavier than in the standard window. This is the case for kination, or in general for scenarios with $\omega >1/3$. However, if $\omega <1/3$, as in the case of an early matter domination, the decay of $\varphi$ injects additional entropy relative to the case of the standard model, diluting this way the preexisting axion abundance, and rendering lighter axions viable. For a misalignment angle $0.5<{\theta }_i<\pi /\sqrt{3}$, the usual axion window becomes expanded to $4\times 10^{-9}$ eV $\lesssim m_a\lesssim 2\times 10^{-5}$ eV for the case of an early matter domination, or to $2\times 10^{-6}$ eV $\lesssim m_a\lesssim 10^{-2}$ eV for the case of kination. Interestingly, the coupling axion-photon in such a wider range can be probed with next generation experiments such as ABRACADABRA, KLASH, ADMX, MADMAX, and ORGAN. Axion dark matter searches may therefore provide a unique tool to probe the history of the universe before Big Bang nucleosynthesis.

   hep-phastro-ph.COJCAP(2021)·49 citations
4. 04*

   Extract the energy scale of anomalous $\gamma \gamma \to W^{+}{W}^{-}$ scattering in the vector boson scattering process using artificial neural networks

   Ji-Chong Yang🇨🇳 · Jin-Hua Chen🇨🇳 · Yu-Chen Guo🇨🇳

   As a model independent approach to search for the signals of new physics~(NP) beyond the Standard Model~(SM), the SM effective field theory~(SMEFT) draws a lot of attention recently. The energy scale of a process is an important parameter in the study of an EFT such as the SMEFT. However, for the processes at a hadron collider with neutrinos in the final states, the energy scales are difficult to reconstruct. In this paper, we study the energy scale of anomalous $\gamma \gamma \to W^{+}{W}^{-}$ scattering in the vector boson scattering~(VBS) process $pp\to jj{\ell }^{+}{\ell }^{-}\nu \bar{\nu }$ at the large hadron collider~(LHC) using artificial neural networks~(ANNs). We find that the ANN is a powerful tool to reconstruct the energy scale of $\gamma \gamma \to W^{+}{W}^{-}$ scattering. The factors affecting the effects of ANNs are also studied. In addition, we make an attempt to interpret the ANN and arrive at an approximate formula which has only five fitting parameters and works much better than the approximation derived from kinematic analysis. With the help of ANN approach, the unitarity bound is applied as a cut on the energy scale of $\gamma \gamma \to W^{+}{W}^{-}$ scattering, which is found to has a significant suppressive effect on signal events. The sensitivity of the process $pp\to jj{\ell }^{+}{\ell }^{-}\nu \bar{\nu }$ to anomalous $\gamma \gamma WW$ couplings and the expected constraints on the coefficients at current and possible future LHC are also studied.

   hep-phJHEP(2021)·15 citations
5. 05*

   Possible studies of gluon transversity in the spin-1 deuteron at hadron-accelerator facilities

   S. Kumano (KEK/J-PARC)🇯🇵 · Qin-Tao Song (Zhengzhou University)🇨🇳

   Chiral-odd gluon transversity distribution could shed light on a new aspect of hadron physics. Although we had much progress recently on quark transversity distributions, there is no experimental measurement on the gluon transversity. The gluon trasversity does not exist in the spin-1/2 nucleons and it exists in the spin-1 deuteron. Therefore, it could probe new hadron physics in the deuteron beyond the basic bound system of a proton and a neutron because the nucleons cannot contribute directly. Here, we explain that the gluon transversity can be measured at hadron accelerator facilities, such as Fermilab and NICA, in addition to charged-lepton scattering measurements at lepton accelerator facilities by showing cross sections of the proton-deuteron Drell-Yan process as an example.

   hep-phhep-exhep-latnucl-thSciPost Phys.Proc.(2022)·0 citations
6. 06*

   Proton Shell Structure

   Wei Kou🇨🇳 · Chengdong Han🇨🇳 · Xurong Chen🇨🇳

   We study the internal structure of the proton and propose a shell structure model of the proton. Based on the mass distribution and mass radius of proton we analyze the experiments at different energy scales and conclude that there should be shell structure inside proton, and the quark and gluon shells are energy-scale-dependent. We successfully explain the dip-like structure in the proton-proton elastic scattering cross section distribution from TOTEM Collaboration using the mass decomposition of proton and the proton shell structure at different energy scales.

   hep-ph3 citations
7. 07*

   Effect of color reconnection on multiplicity dependent charged particle production in Pythia-generated $pp$ collisions at the LHC energies

   Pranjal Sarma🇮🇳 · Banajit Barman🇮🇳 · Buddhadeb Bhattacharjee🇮🇳

   The transverse momentum ($p_{\mathrm{T}}$) spectra of inclusive charged particles and its dependence on charged-particle multiplicity are studied in pp collisions at $\sqrt{s}$ = 7 and 13 TeV using the Monte Carlo event generator PYTHIA Monash. The results of the minimum bias pp collisions are compared with the ALICE published results at the same energies. The variations of the effective temperature (T${}_{\mathrm{Eff}}$) and average transverse momentum ($⟨p_{\mathrm{T}}⟩$) with charged-particle multiplicity are also studied. The $p_{\mathrm{T}}$ spectra of the charged particles are observed to get harder with increasing charged-particle multiplicity. Moreover, a sharp increase in the T${}_{\mathrm{Eff}}$ and $⟨p_{\mathrm{T}}⟩$ with increasing multiplicity followed by a gradual decrease with the further increase in multiplicity could also be observed. Further, it could be observed that the color reconnection (CR) mechanism has a considerable effect on flattening the T${}_{\mathrm{Eff}}$ and $⟨p_{\mathrm{T}}⟩$ with increasing multiplicity, which indicates that phase-transition may not necessarily be the only mechanism that could give rise to such an effect.

   hep-phEPJA(2023)·8 citations
8. 08*

   Perfect $D{D}^{\ast }$ molecular prediction matching the $T_{cc}$ observation at LHCb

   Ning Li🇨🇳 · Zhi-Feng Sun🇨🇳 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳

   In 2012, we investigated the possible molecular states composed of two charmed mesons [Phys.Rev. D 88, 114008 (2013), arXiv:1211.5007 [hep-ph](2012)]. The $D^{\ast }D$ system with the quantum numbers of $I(J^P)=0(1^{+})$ was found to be a good candidate of the loosely bound molecular state. This state is very close to the $D^{\ast }D$ threshold with a binding energy around 0.47 MeV. This prediction was confirmed by the new LHCb observation of $T_{cc}^{+}$ [see Franz Muheim's talk at the European Physical Society conference on high energy physics 2021].

   hep-phhep-exhep-latChin.Phys.Lett.(2021)·45 citations
9. 09*

   On the origin of matter in the Universe

   Pasquale Di Bari🇬🇧

   The understanding of the physical processes that lead to the origin of matter in the early Universe, creating both an excess of matter over anti-matter that survived until the present and a dark matter component, is one of the most fascinating challenges in modern science. The problem cannot be addressed within our current description of fundamental physics and, therefore, it currently provides a very strong evidence of new physics. Solutions can either reside in a modification of the standard model of elementary particle physics or in a modification of the way we describe gravity, based on general relativity, or at the interface of both. We will mainly discuss the first class of solutions. Traditionally, models that separately explain either the matter-antimatter asymmetry of the Universe or dark matter have been proposed. However, in the last years there has also been an accreted interest and intense activity on scenarios able to provide a unified picture of the origin of matter in the early universe. In this review we discuss some of the main ideas emphasising primarily those models that have more chances to be experimentally tested during next years. Moreover, after a general discussion, we will focus on extensions of the standard model that can also address neutrino masses and mixing, since this is currently the only evidence of physics beyond the standard model coming directly from particle physics and it is, therefore, reasonable they might also provide a solution to the problem of the origin of matter in the universe.

   hep-phastro-ph.COhep-exPPNP(2022)·42 citations
10. 10*

    Critical properties of various sizes of cluster in the Ising percolation transition

    Lizhu Chen🇨🇳 · Yeyin Zhao🇨🇳 · Xiaobing Li🇨🇳 · Zhiming Li🇨🇳 · Yuanfang Wu🇨🇳

    It is proposed that the $O(n)$ spin and geometrical percolation models can help to study the QCD phase diagram due to the universality properties of the phase transition. In this paper, correlations and fluctuations of various sizes of cluster in the Ising model are systematically studied. With a finite size system, we demonstrate how to use the finite size scaling and fixed point behavior to search for critical point. At critical point, the independency of system size is found from skewness and kurtosis of the maximum, second and third largest cluster and their correlations. It is similar to the Binder-ratio, which has provided a remarkable identification of the critical point. Through an explanation of the universal characteristic of skewness and kurtosis of the order parameter, a possible application to the relativistic heavy-ion collisions is also discussed.

    hep-phnucl-thIJMPE(2021)·3 citations
11. 11*

    Momentum transfer dependence of heavy quarkonium electroproduction

    M. Krelina🇨🇿 · J. Nemchik🇨🇿

    We investigate the momentum transfer dependence of differential cross sections $d\sigma /dt$ in diffractive electroproduction of heavy quarkonia on proton targets. Model predictions for $d\sigma /dt$ within the light-front QCD dipole formalism are based on a realistic model for a proper correlation between the impact parameter $\vec{b}$ of a collision and color dipole orientation $\vec{r}$. We demonstrate a significance of $\vec{b}-\vec{r}$ correlation by comparing with a standard simplification $\vec{b}\parallel \vec{r}$, frequently used in the literature.

    hep-phSciPost Phys.Proc.(2022)·0 citations
12. 12*

    Baryogenesis and gravitational waves in the Zee-Babu Model

    Vo Quoc Phong🇻🇳 · Nguyen Chi Thao🇻🇳 · Hoang Ngoc Long🇻🇳

    To explain the matter-antimatter asymmetry in the Zee-Babu (ZB) model, the sphaleron process in the baryogenesis scenario is calculated. It always satisfies the de-coupling condition and the strength of phase transition ($S$) is always greater than $1$ in the presence of triggers other than that in the Standard Model, which are singly ($h^{\pm }$) and doubly ($k^{\pm \pm }$) charged scalar bosons. Sphaleron energies are in the range of 5-10 TeV, in calculation with bubble profiles containing free parameters and assuming nuclear bubbles of $h^{\pm }$ and $k^{\pm \pm }$ are very small. We tested the scaling law of sphaleron again with an average error of $10\%$. When the temperature is close to the critical one ($T_c$), the density of nuclear bubble is produced very large and decreases as the temperature decreases. The key parameter is $\alpha$ which results in the gravitational wave density parameter ($\Omega h^2$) in the range of $10^{-14}$ to $10^{-12}$ when $\beta /H^{\ast }=22.5$, this is not enough to detect gravitational waves from electroweak phase transition (EWPT) according to the present LISA data but may be detected in the future. As the larger strength of phase transition is, the more $\alpha$ increases (this increase is almost linear with $S$), the larger the gravitational wave density parameter is. Also in the context of considering the generation of gravitational waves, in the ZB model we calculated $\alpha \sim \text{a few}\times 10^{-2}\ll 1$, so rigorously conclude that the EWPT is not strong even though $S>1$. We also suggest that, for a model with a lot of extra scalar particles and particles which play a role in mass generation, the stronger the EWPT process and the larger $\Omega h^2$ can be.

    hep-phEPJC(2022)·7 citations
13. 13*

    Producing and constraining self-interacting hidden sector dark matter

    Laurent Vanderheyden🇧🇪

    In this thesis, we start by reviewing all constraints applying on self-interacting DM with a light mediator considering well-known Higgs portal and Kinetic Mixing portal models as concrete examples. Then, we elaborate on the Sommerfeld effect, and we study its many implications on self-interacting DM models with light mediator. Next, we investigate how to account for the DM relic abundance in such portal models which present a generic structure with three populations (Standard Model, DM and mediator particles) connected to each other through three interactions resulting from two coupling strengths. It appears that this can be done through five different dynamical ways which give rise to nine regimes among which four are new. Those new production regimes are relevant for a situation where the hidden sector particles are not thermally connected to the visible vector particles. We further study the possibility of a thermally disconnected Hidden Sector and establish the general allowed parameter space for DM thermal candidates in the hidden-to-visible temperature ratio versus DM mass plane. We show that, in this framework, simple portal models such as the two we consider can alleviate tensions at small scale while offering suitable DM candidates. Other minimal self-interacting DM with light mediator frameworks which consistently fulfil all constraints are also proposed and explored.

    hep-ph3 citations
14. 14*

    Intrinsic charm in the nucleon and forward production of charm: a new constrain from IceCube Neutrino Observatory

    Rafal Maciula🇵🇱 · Victor P. Goncalves🇧🇷 · Antoni Szczurek🇵🇱

    The predictions for the atmospheric neutrino flux at high energies strongly depend on the contribution of prompt neutrinos, which are determined by the production of charmed meson in the atmosphere at very forward rapidities. Here we estimate the related cross sections taking into account the presence of an intrinsic charm (IC) component in the proton wave function. The impact on the predictions for the prompt neutrino flux is investigated assuming different values for the probability to find the IC in the nucleon.

    hep-phSciPost Phys.Proc.(2022)·0 citations
15. 15*

    $S$-wave contributions to the $B_{(s)}\to {\chi }_{c1}(\pi \pi ,K\pi ,KK)$ decays

    Meng-Kun Jia🇨🇳 · Chao-Qi Zhang🇨🇳 · Jia-Ming Li🇨🇳 · Zhou Rui🇨🇳

    We make a detailed study of the three-body decays $B_{(s)}\to {\chi }_{c1}h{h}^{\prime }$, where $h^{{(}^{\prime })}$ is either a pion or kaon, by taking into account the $S$-wave states in the $h{h}^{\prime }$ invariant mass distribution within the perturbative QCD approach. The two meson distribution amplitudes (DAs) are introduced to capture the strong interaction related to the production of the $h{h}^{\prime }$ system. We calculate the branching ratios for the $S$-wave components and observe large values of order $10^{-4}$ for some Cabibbo-favored decays, which are accessible to the LHCb and Belle II experiments. The obtained branching ratio $\mathcal{B}(B\to {\chi }_{c1}{K}_0^{\ast }(1430)(\to K^{+}{\pi }^{-}))=(5.1_{-0.8}^{+0.6})\times 10^{-5}$ consistent with the data from Belle within errors. Moreover, we also predict the differential distributions in the $h{h}^{\prime }$ invariant mass for the decays under consideration, which await the future experimental test. In addition, the corresponding ${\chi }_{c1}(2P)$ channels are also investigated, which are helpful to clarify the nature of the $X(3872)$ state.

    hep-phPRD(2021)·5 citations
16. 16*

    2-loop short-distance constraints for the $g-2$ HLbL

    Johan Bijnens🇸🇪 · Nils Hermansson-Truedsson🇨🇭 · Laetitia Laub🇨🇭 · Antonio Rodríguez-Sánchez🇫🇷

    The recent experimental measurement of the muon $g-2$ at Fermilab National Laboratory, at a $4.2\sigma$ tension with the Standard Model prediction, highlights the need for further improvements on the theoretical uncertainties associated to the hadronic sector. In the framework of the operator product expansion in the presence of a background field, the short-distance behaviour of the hadronic light-by-light contribution was recently studied. The leading term in this expansion is given by the massless quark-loop, which is numerically dominant compared to non-perturbative corrections. Here, we present the perturbative QCD correction to the massless quark-loop and estimate its size numerically. In particular, we find that for scales above 1 GeV it is relatively small, in general roughly $-10\%$ the size of the massless quark-loop. The knowledge of these short-distance constraints will in the future allow to reduce the systematic uncertainties in the Standard Model prediction of the hadronic light-by-light contribution to the $g-2$.

    hep-phNucl.Part.Phys.Proc.(2022)·1 citation
17. 17*

    The top quark electro-weak couplings after LHC Run 2

    Víctor Miralles🇪🇸 · Marcos Miralles López🇪🇸 · María Moreno Llácer🇪🇸 · Ana Peñuelas🇪🇸 · Martín Perelló🇪🇸 · Marcel Vos🇪🇸

    Recent measurements at the Large Hadron Collider allow for a robust and precise characterisation of the electro-weak interactions of the top quark. We present the results of a global analysis at next-to-leading order precision including LHC, LEP/SLD and Tevatron data in the framework of the Standard Model Effective Field Theory. We include a careful analysis of the impact of correlations among measurements, as well as of the uncertainties in the Effective Field Theory setup itself. We find remarkably robust global fit results, with central values in good agreement with the Standard Model prediction, and 95% probability bounds on Wilson coefficients that range from $\pm$ 0.35 to $\pm$ 8 TeV${}^{-2}$. This result represents a considerable improvement over previous studies, thanks to the addition of differential cross-section measurements in associated production processes of top quarks and neutral gauge bosons.

    hep-phhep-exJHEP(2022)·51 citations
18. 18*

    Triply-heavy tetraquarks in an extended relativized quark model

    Qi-Fang Lü🇨🇳 · Dian-Yong Chen🇨🇳 · Yu-Bing Dong🇨🇳 · Elena Santopinto🇮🇹

    In this paper, we adopt an extended relativized quark model to investigate the triply-heavy tetrquarks systematically. The mass spectra are obtained by solving the four-body relativized Hamiltonian including the Coulomb potential, confining potential, spin-spin interactions, and relativistic corrections. We find that all of the triply-heavy tetraquarks lie above the corresponding meson-meson thresholds, and thus no stable one exists. In particular, besides the spin-spin interactions, the Coulomb and confining potentials also contribute to the mass splittings in the $cb\bar{c}\bar{q}$ and $cb\bar{b}\bar{q}$ systems. Moreover, the whole mass spectra for triply heavy tetraquarks show quite similar patterns, which preserve the light flavor SU(3) symmetry and heavy quark symmetry well. Through the fall-apart mechanism, the triply-heavy tetraquarks may easily decay into the heavy quarkonium plus heavy-light mesons, which are good candidates for investigation in future experiments.

    hep-phhep-exnucl-thPRD(2021)·24 citations
19. 19*

    Central exclusive diffractive production of axial-vector $f_1$ mesons in proton-proton collisions

    Piotr Lebiedowicz🇵🇱 · Josef Leutgeb🇦🇹 · Otto Nachtmann🇩🇪 · Anton Rebhan🇦🇹 · Antoni Szczurek🇵🇱

    Exclusive production of axial-vector $f_1(1285)$ meson in proton-proton collisions via pomeron-pomeron fusion within the tensor-pomeron approach is discussed. Two ways to construct the pomeron-pomeron-$f_1$ coupling are presented. We adjust the parameters of our model to the WA102 experimental data and compare with predictions of the Sakai-Sugimoto model. Predictions for LHC experiments are given.

    hep-phhep-exSciPost Phys.Proc.(2022)·1 citation
20. 20*

    Deciphering Weak Decays of Triply Heavy Baryons by SU(3) Analysis

    Fei Huang🇨🇳 · Ji Xu🇨🇳 · Xi-Ruo Zhang🇨🇳

    Baryons with three heavy quarks are the last missing pieces of the lowest-lying baryon multiplets in the quark model after the discovery of doubly heavy baryons. In this work, we study nonleptonic weak decays of triply heavy baryons ${\Omega }_{ccc}^{++}$, ${\Omega }_{bbb}^{-}$, ${\Omega }_{ccb}^{+}$, and ${\Omega }_{cbb}^0$. Decay amplitudes for various processes have been parametrized in terms of the SU(3) irreducible nonperturbative amplitudes. A number of relations for the partial decay widths can be deduced from these results that can be examined in future. Some decay channels and cascade decay modes which likely to be used to reconstruct the triply heavy baryons have been also listed.

    hep-phEPJC(2021)·13 citations
21. 21*

    Time reversal-odd effects in QCD and beyond

    Dylan Manna🇺🇸 · Andrea Signori🇮🇹 · Christine Aidala🇺🇸

    In this paper we will describe a parallel between phenomenological and symmetry-based descriptions of the process dependence of the time-reversal-odd phenomena in QCD, such as the Sivers effect, with the goal of defining the essential elements that lead to such process dependence in QCD. This will then serve as a starting point to explore possible generalizations in a different gauge theory.

    hep-phhep-exnucl-thSciPost Phys.Proc.(2022)·2 citations
22. 22*

    Light Sterile Neutrinos and a High-Quality Axion from a Holographic Peccei-Quinn Mechanism

    Peter Cox🇦🇺 · Tony Gherghetta🇺🇸 · Minh D. Nguyen🇺🇸

    We present a 5D axion-neutrino model that explains the Standard Model fermion mass hierarchy and flavor structure, while simultaneously generating a high-quality axion. The axion and right-handed neutrinos transform under a 5D Peccei-Quinn gauge symmetry, and have highly suppressed profiles on the UV brane where the symmetry is explicitly broken. This setup allows neutrinos to be either Dirac, or Majorana with hierarchically small sterile neutrino masses. The axion decay constant originates from the IR scale, which in the holographically dual 4D description corresponds to the confinement scale of some new strong dynamics with a high-quality global Peccei-Quinn symmetry that produces a composite axion and light, composite sterile neutrinos. The sterile neutrinos could be observed in astrophysical or laboratory experiments, and the model predicts specific axion--neutrino couplings.

    hep-phhep-thPRD(2022)·15 citations
23. 23*

    NLO collinear factorization of large mass diphoton photoproduction amplitude

    Oskar Grocholski🇵🇱 · Bernard Pire🇫🇷 · Paweł Sznajder🇵🇱 · Lech Szymanowski🇵🇱 · Jakub Wagner🇵🇱

    We calculate large mass diphoton exclusive photoproduction in the framework of collinear QCD factorization at next to leading order in {\alpha}s and at leading twist. Collinear divergences of the coefficient function are absorbed by the evolution of the generalized parton distributions (GPDs). This result enlarges the existing factorization proofs to 2 -> 3 processes, opening new reactions to a trustable extraction of GPDs.

    hep-phhep-exnucl-exSciPost Phys.Proc.(2022)·0 citations
24. 24*

    Charged lepton flavor violation in light of Muon $g-2$

    Wei-Shu Hou🇹🇼 · Girish Kumar🇹🇼

    The recent confirmation of the muon $g-2$ anomaly by the Fermilab g-2 experiment may harbinger a new era in $\mu$ and $\tau$ physics. In the context of general two Higgs doublet model, the discrepancy can be explained via one-loop exchange of sub-TeV exotic scalar and pseudoscalars, namely $H$ and $A$, that have flavor changing neutral couplings ${\rho }_{\tau \mu }$ and ${\rho }_{\mu \tau }$ at $\sim 20$ times the usual tau Yukawa coupling, ${\lambda }_{\tau }$. Taking ${\rho }_{\ell {\ell }^{\prime }}\sim {\lambda }_{\min (\mathrm{\ell },{\mathrm{\ell }}^{\prime })}$, we show that the above solution to muon $g-2$ then predicts enhanced rates of various charged lepton flavor violating processes, which should be accessible at upcoming experiments. We cover muon related processes such as $\mu \to e\gamma$, $\mu \to eee$ and $\mu N\to eN$, and $\tau$ decays $\tau \to \mu \gamma$ and $\tau \to \mu \mu \mu$. A similar one-loop diagram with ${\rho }_{e\tau }={\rho }_{\tau e}=\mathcal{O}({\lambda }_e)$ induces $\mu \to e\gamma$, bringing the rate right into the sensitivity of the MEG~II experiment. The $\mu e\gamma$ dipole can be probed further by $\mu \to 3e$ and $\mu N\to eN$. With its promised sensitivity range and ability to use different nuclei, the $\mu N\to eN$ conversion experiments can not only make discovery, but access the extra diagonal quark Yukawa couplings ${\rho }_{qq}$. For the $\tau$ lepton, we find that $\tau \to \mu \gamma$ would probe ${\rho }_{\tau \tau }$ down to ${\lambda }_{\tau }$ or lower, while $\tau \to 3\mu$ would probe ${\rho }_{\mu \mu }$ to $\mathcal{O}({\lambda }_{\mu })$.

    hep-phEPJC(2021)·16 citations
25. 25*

    Revisiting ${\gamma }^{\ast }\to \gamma {\pi }^0\eta$ near the $\varphi (1020)$ using analyticity and the left-cut structure

    B. Moussallam🇫🇷

    Amplitudes of the form ${\gamma }^{\ast }(q^2)\to \gamma P_1{P}_2$ appear as sub-processes in the computation of the muon $g-2$. We test a proposed theoretical modelling against very precise experimental measurements by the KLOE collaboration at $q^2=m_{\varphi }^2$. Starting from an exact parameter-free dispersive representation for the $S$-wave satisfying QCD asymptotic constraints and Low's soft photon theorem we derive, in an effective theory spirit, a two-channel Omnès integral representation which involves two subtraction parameters. The discontinuities along the left-hand cuts which, for timelike virtualities, extend both on the real axis and into the complex plane are saturated by the contributions from the light vector mesons. In the case of $P_1{P}_2=\pi \eta$, we show that a very good fit of the KLOE data can be achieved with two real parameters, using a $T$-matrix previously determined from $\gamma \gamma$ scattering data. This indicates a good compatibility between the two data sets and confirms the validity of the $T$-matrix. The resulting amplitude is also found to be compatible with the chiral soft pion theorem. Applications to the $I=1$ scalar form factors and to the $a_0(980)$ resonance complex pole are presented.

    hep-phEPJC(2021)·13 citations
26. 26*

    Collider signatures of vector-like fermions from a flavor symmetric model

    Cesar Bonilla🇨🇱 · A. E. Cárcamo Hernández🇨🇱 · João Gonçalves🇵🇹 · Felipe F. Freitas🇵🇹 · António P. Morais🇵🇹 · R. Pasechnik🇸🇪

    We propose a model with two Higgs doublets and several $SU(2)$ scalar singlets with a global non-Abelian flavor symmetry ${\mathcal{Q}}_6\times {\mathcal{Z}}_2$. This discrete group accounts for the observed pattern of fermion masses and mixing angles after spontaneous symmetry breaking. In this scenario only the third generation of fermions get their masses as in the Standard Model (SM). The masses of the remaining fermions are generated through a seesaw-like mechanism. To that end, the matter content of the model is enlarged by introducing electrically charged vector-like fermions (VLFs), right handed Majorana neutrinos and several SM scalar singlets. Here we study the processes involving VLFs that are within the reach of the Large Hadron Collider (LHC). We perform collider studies for vector-like leptons (VLLs) and vector-like quarks (VLQs), focusing on double production channels for both cases, while for VLLs single production topologies are also included. Utilizing genetic algorithms for neural network optimization, we determine the statistical significance for a hypothetical discovery at future LHC runs. In particular, we show that we can not safely exclude VLLs for masses greater than $200\mathrm{GeV}$. For VLQ's in our model, we show that we can probe their masses up to 3.8 TeV, if we take only into account the high-luminosity phase of the LHC. Considering Run-III luminosities, we can also exclude VLQs for masses up to $3.4\mathrm{TeV}$. We also show how the model with predicted VLL masses accommodates the muon anomalous magnetic moment.

    hep-phhep-exJHEP(2022)·19 citations
27. 27*

    Two-Loop Hexa-Box Integrals for Non-Planar Five-Point One-Mass Processes

    Samuel Abreu🇨🇭 · Harald Ita🇩🇪 · Ben Page🇨🇭 · Wladimir Tschernow🇩🇪

    We present the calculation of the three distinct non-planar hexa-box topologies for five-point one-mass processes. These three topologies are required to obtain the two-loop virtual QCD corrections for two-jet-associated W, Z or Higgs-boson production. Each topology is solved by obtaining a pure basis of master integrals and efficiently constructing the associated differential equation with numerical sampling and unitarity-cut techniques. We present compact expressions for the alphabet of these non-planar integrals, and discuss some properties of their symbol. Notably, we observe that the extended Steinmann relations are in general not satisfied. Finally, we solve the differential equations in terms of generalized power series and provide high-precision values in different regions of phase space which can be used as boundary conditions for subsequent evaluations.

    hep-phhep-thJHEP(2022)·79 citations
28. 28*

    X(6200) as a compact tetraquark in the QCD string model

    A. V. Nefediev🇷🇺

    Recently the LHCb Collaboration announced the first observation of nontrivial structures in the double-$J/\psi$ mass spectrum in the mass range 6.2-7.2 GeV, and a theoretical coupled-channel analysis of these data performed in Phys. Rev. Lett. 126, 132001 (2021) evidenced the existence of a new state $X(6200)$ close to the double-$J/\psi$ threshold. Although its molecular interpretation seems the most plausible assumption, the present data do not exclude an admixture of a compact component in its wave function, for which a fully-charmed compact tetraquark is the most natural candidate. It is argued in this work that the QCD string model is compatible with the existence of a compact $cc\bar{c}\bar{c}$ state bound by QCD forces just below the double-$J/\psi$ threshold. A nontrivial interplay of the quark dynamics associated with this compact state and the molecular dynamics provided by soft gluon exchanges between $J/\psi$ mesons is discussed and the physical $X(6200)$ is argued to be a shallow bound state, in agreement with the results of the aforementioned coupled-channel analysis of the LHCb data.

    hep-phhep-exhep-latEPJC(2021)·28 citations
29. 29*

    Correlations between azimuthal asymmetries and multiplicity and mean transverse momentum in small collisions systems in the CGC

    Tolga Altinoluk🇵🇱 · Néstor Armesto🇪🇸 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱 · Vladimir V. Skokov🇺🇸

    Considering a dilute-dense situation suitable for pA collisions, we compute in the Color Glass Condensate the correlation between azimuthal asymmetries, specifically the squared second Fourier coefficient $v_2^2$, and the total multiplicity in the event. We also analyse the correlation between $v_2^2$ and the mean squared transverse momentum of particles in the event. In both cases, we find that the correlations are generally very small, consistent with the observations. We also note an interesting sharp change in the value of $v_2^2$ and its correlations as a function of the width of the transverse momentum bin, related with a change of the dominance of Bose and HBT quantum correlations.

    hep-phnucl-thSciPost Phys.Proc.(2022)·1 citation
30. 30*

    Two-body lepton-flavour-violating decays in a 2HDM with soft family-lepton-number breaking

    Darius Jurčiukonis🇱🇹 · Luis Lavoura🇵🇹

    We evaluate the decays ${\ell }_1^{\pm }\to {\ell }_2^{\pm }\gamma$, $Z\to {\ell }_1^{+}{\ell }_2^{-}$, and $h\to {\ell }_1^{+}{\ell }_2^{-}$, where ${\ell }_1$ and ${\ell }_2$ are charged leptons with different flavours and $h$ is the scalar particle with mass 125.25 GeV, in a two-Higgs-doublet model where all the Yukawa-coupling matrices conserve the lepton flavours but the Majorana mass terms of the right-handed neutrinos break the flavour lepton numbers. We find that (1) the decays ${\ell }_1^{\pm }\to {\ell }_2^{\pm }\gamma$ require large Yukawa couplings and very light right-handed neutrinos in order to be visible, (2) the decays $Z\to {\ell }_1^{+}{\ell }_2^{-}$ will be invisible in all the planned experiments, except in a very restricted range of circumstances, but (3) the decays $h\to {\ell }_1^{+}{\ell }_2^{-}$ may be detected in future experiments for rather relaxed sets of input parameters.

    hep-phJHEP(2022)·13 citations
31. 31*

    The Baikal-GVD neutrino telescope as an instrument for studying Baikal water luminescence

    V. A. Allakhverdyan🇷🇺 · A. D. Avrorin🇷🇺 · A. V. Avrorin🇷🇺 · V. M. Aynutdinov🇷🇺 · R. Bannasch🇩🇪 · Z. Bardačová🇸🇰 · I. A. Belolaptikov🇷🇺 · I. V. Borina🇷🇺 · V. B. Brudanin🇷🇺 · N. M. Budnev🇷🇺 · V. Y. Dik🇷🇺 · G. V. Domogatsky🇷🇺 and 54 other authors

    We present data on the Baikal water luminescence collected with the Baikal-GVD neutrino telescope. This three-dimensional array of photo-sensors allows the observation of time and spatial variations of the ambient light field. We report on annual increase of luminescence activity in years 2018-2020. We observed a unique event of a highly luminescent layer propagating upwards with a maximum speed of 28 m/day for the first time.

    hep-phastro-ph.HEPoS(2021)·7 citations
32. 32*

    Inflation in Energy-Momentum Squared Gravity in Light of Planck2018

    Marzieh Faraji🇮🇷 · Narges Rashidi🇮🇷 · Kourosh Nozari🇮🇷

    We study cosmological dynamics of the energy-momentum squared gravity. By adding the squared of the matter field's energy-momentum tensor ($\zeta {\text{T}}^2$) to the Einstein Hilbert action, we obtain the Einstein's field equations and study the conservation law. We show that the presence of $\zeta {\text{T}}^2$ term, breaks the conservation of the energy-momentum tensor of the matter fields. However, an effective energy-momentum tensor in this model is conserved in time. By considering the FRW metric as the background, we find the Friedmann equations and by which we explore the cosmological inflation in $\zeta {\text{T}}^2$ model. We perform numerical analysis on the perturbation parameters and compare the results with Planck2018 different data sets at $68\%$ and $95\%$ CL, to obtain some constraints on the coupling parameter $\zeta$. We show that \textbf{ for $0<\zeta \le 2.1\times 10^{-5}$, the $\zeta {\text{T}}^2$ gravity is an observationally viable model of inflation.

    ↳ gr-qcastro-ph.COhep-phhep-thEur.Phys.J.Plus(2022)·11 citations
33. 33*

    Nucleon-nucleon scattering with perturbative pions: The uncoupled $P$-wave channels

    J. B. Habashi🇺🇸

    The uncoupled $P$-wave channels of nucleon-nucleon scattering are studied in an effective field theory (EFT) including a perturbative dibaryon field and perturbative pions. Good agreement between EFT results and the Nijmegen partial wave analysis is observed up to a center-of-mass momentum $k\approx 400$ MeV. Using a method that combines renormalization and fitting together, the long-standing convergence problem of EFTs in these channels with perturbative pions, for momenta above the pion mass is addressed from a new perspective.

    ↳ nucl-thhep-lathep-phPRC(2022)·3 citations
34. 34*

    Pair production of charged IDM scalars at high energy CLIC

    Jan Klamka🇵🇱

    The Compact Linear Collider (CLIC) was proposed as the next energy-frontier infrastructure at CERN, to study e${}^{+}$e${}^{-}$ collisions at three centre-of-mass energy stages: 380 GeV, 1.5 TeV and 3 TeV. The main goal of its high-energy stages is to search for the new physics beyond the Standard Model (SM). The Inert Doublet Model (IDM) is one of the simplest SM extensions and introduces four new scalar particles: H${}^{\pm }$, A and H; the lightest, H, is stable and hence a natural dark matter (DM) candidate. A set of benchmark points is considered, which are consistent with current theoretical and experimental constraints and promise detectable signals at future colliders. Prospects for observing pair-production of the IDM scalars at CLIC were previously studied using signatures with two leptons in the final state. In the current study, discovery reach for the IDM charged scalar pair-production is considered for the semi-leptonic final state at the two high-energy CLIC stages. Full simulation analysis, based on the current CLIC detector model, is presented for five selected IDM scenarios. Results are then extended to the larger set of benchmarks using the Delphes fast simulation framework. The CLIC detector model for Delphes has been modified to take pile-up contribution from the beam-induced $\gamma \gamma$ interactions into account, which is crucial for the presented analysis. Results of the study indicate that heavy, charged IDM scalars can be discovered at CLIC for most of the proposed benchmark scenarios, with very high statistical significance.

    ↳ hep-exhep-phSciPost Phys.Proc.(2022)·3 citations
35. 35*

    Searches for invisible scalar decays at CLIC

    Krzysztof Mekala🇵🇱 · Aleksander Filip Zarnecki🇵🇱 · Bohdan Grzadkowski🇵🇱 · Michal Iglicki🇵🇱

    The Compact Linear Collider (CLIC) is a proposed TeV-scale high-luminosity electron-positron collider at CERN. The first CLIC running stage, at 380\,GeV, will focus on precision Higgs boson and top quark studies while the main aim of the subsequent high-energy stages, at 1.5 TeV and 3 TeV, is to extend the sensitivity of CLIC to different Beyond the Standard Model (BSM) scenarios. We studied the prospects for measuring invisible Higgs boson and additional heavy scalar decays using CLIC data at 380 GeV and 1.5 TeV. The analysis is based on the WHIZARD event generator, with fast simulation of the CLIC detector response parametrised by the DELPHES package. We present the expected limits for the invisible decays of the 125 GeV Higgs boson, the cross section limits for production of an additional neutral Higgs scalar, assuming its invisible decays, and limits on the mixing angle between the SM-like Higgs boson and the new scalar of the "dark sector" in the framework of the vector-fermion dark matter model.

    ↳ hep-exhep-phSciPost Phys.Proc.(2022)·4 citations
36. 36*

    ${\Lambda }_c\to \Lambda$ Form Factors in Lattice QCD

    Huseyin Bahtiyar🇹🇷

    Studying the semileptonic decays of charmed particles is prominent in testing the standard model of particle physics. Motivated by recent experimental progress in weak decays of the charm baryon sector, we study the form factors of ${\Lambda }_c\to \Lambda {\ell }^{+}\nu$ transition on two flavor lattices. We compute two- and three-point functions, extract the dimensionless projected correlators, and combine them to form the Weinberg form factors. In the zero transferred momentum limit $f_1$, $f_2$ and $g_1$ form factors are found to be in agreement with other models, furthermore $f_3$ and $g_3$ form factors are comparable to model determinations. The $g_2$ form factor, on the other hand, is found to be mildly larger. We also evaluate the helicity form factors, which is consistent with the previous lattice studies.

    ↳ hep-lathep-phTurk.J.Phys.(2021)·11 citations
37. 37*

    Dissecting the $H_0$ and $S_8$ tensions with Planck + BAO + supernova type Ia in multi-parameter cosmologies

    Luis A. Anchordoqui🇺🇸 · Eleonora Di Valentino🇬🇧 · Supriya Pan🇮🇳 · Weiqiang Yang🇨🇳

    The mismatch between the locally measured expansion rate of the universe and the one inferred from observations of the cosmic microwave background (CMB) assuming the canonical $\Lambda$CDM model has become the new cornerstone of modern cosmology, and many new-physics set ups are rising to the challenge. Concomitant with the so-called $H_0$ problem, there is evidence of a growing tension between the CMB-preferred value and the local determination of the weighted amplitude of matter fluctuations $S_8$. It would be appealing and compelling if both the $H_0$ and $S_8$ tensions were resolved at once, but as yet none of the proposed new-physics models have done so to a satisfactory degree. Herein, we adopt a systematic approach to investigate the possible interconnection among the free parameters in several classes of models that typify the main theoretical frameworks tackling the tensions on the universe expansion rate and the clustering of matter. Our calculations are carried out using the publicly available Boltzmann solver CAMB in combination with the sampler CosmoMC. We show that even after combining the leading classes of models sampling modifications of both the early and late time universe a simultaneous solution to the $H_0$ and $S_8$ tensions remains elusive.

    ↳ astro-ph.COhep-phJHEAp(2021)·98 citations
38. 38*

    Longitudinal double helicity asymmetry $A_{LL}$ from direct photon, jet and charged pion production in polarized $\vec{p}+\vec{p}$ collisions

    Zhongling Ji🇺🇸

    Understanding the proton spin composition from the quarks and gluons spin polarization and their motion is important to test various kinds of sum rules and nonperturbative properties of hadrons. At the Relativistic Heavy Ion Collider (RHIC), we collide longitudinally polarized proton beams and measure the double helicity asymmetry $A_{LL}$, which is an important physical quantity for extracting the polarized parton distribution functions (PDFs) of the proton. Direct photon, jet and charged pion production are good channels to probe the gluon spin polarization inside the proton, with the ability to probe also the sign of the gluon spin. Direct photon production is the theoretically ``cleanest'' channel, with little fragmentation contribution, but limited by statistics. On the other hand, jet and charged pion production have more statistics, but include more hard processes and hadronization effects. I will present the recent measurements of direct photon, jet and charged pion $A_{LL}$s at PHENIX and show their complementary roles in extracting the gluon spin.

    ↳ nucl-exhep-phSciPost Phys.Proc.(2022)·1 citation
39. 39*

    Bayesian inference of strange star equation of state using the GW170817 and GW190425 data

    Zhiqiang Miao🇨🇳 · Jin-Liang Jiang🇨🇳 · Ang Li🇨🇳 · Lie-Wen Chen🇨🇳

    The observations of compact star inspirals from LIGO/Virgo provide a valuable tool to study the highly uncertain equation of state (EOS) of dense matter at the densities in which the compact stars reside. It is not clear whether the merging stars are neutron stars or quark stars containing self-bound quark matter. In this work, we explore the allowed bag-model-like EOSs by assuming the merging stars are strange quark stars (SQSs) from a Bayesian analysis employing the tidal deformability observational data of the GW170817 and GW190425 binary mergers. We consider two extreme states of strange quark matter, either in nonsuperfluid or color-flavor locked (CFL) and find the results in these two cases essentially reconcile. In particular, our results indicate that the sound speed in the SQS matter is approximately a constant close to the conformal limit of $c/\sqrt{3}$. The universal relations between the mass, the tidal deformability and the compactness are provided for the SQSs. The most probable values of the maximum mass are found to be $M_{\mathrm{TOV}}=2.10_{-0.12}^{+0.12}(2.15_{-0.14}^{+0.16})M_{\odot }$ for normal (CFL) SQSs at a $90\%$ confidence level. The corresponding radius and tidal deformability for a $1.4M_{\odot }$ star are $R_{1.4}=11.50_{-0.55}^{+0.52}({11.42}_{-0.44}^{+0.52})\mathrm{km}$ and ${\Lambda }_{1.4}={650}_{-190}^{+230}({630}_{-150}^{+220})$, respectively. We also investigate the possibility of GW190814's secondary component $m_2$ of mass $2.59_{-0.09}^{+0.08}{M}_{\odot }$ being an SQS, and find that it could be a CFL SQS with the pairing gap $\Delta$ larger than $244\mathrm{MeV}$ and the effective bag parameter $B_{\mathrm{eff}}^{1/4}$ in the range of $170$ to $192$ MeV, at a $90\%$ confidence level.

    ↳ astro-ph.HEhep-phnucl-thApJL·56 citations
40. 40*

    Constraining the dark energy models using Baryon Acoustic Oscillations: An approach independent of $H_0\cdot r_d$

    Denitsa Staicova🇧🇬 · David Benisty🇬🇧

    The $H_0$ tension and the accompanying $r_d$ tension are a hot topic in current cosmology. In order to remove the degeneracy between the Hubble parameter $H_0$ and the sound horizon scale $r_d$ from the Baryon Acoustic Oscillations (BAO) datasets, we redefine the likelihood by marginalizing over the $H_0\cdot r_d$ parameter and then we perform full Bayesian analysis for different models of dark energy (DE). We find that our uncalibrated by early or late physics {datasets cannot} constrain the DE models properly without further assumptions. By adding the type IA supernova dataset, the models are constrained better with smaller errors on the DE parameters. The two BAO datasets we use -- one with angular measurements and one with angular and radial ones with their covariances, show statistical preferences for different models, with $\Lambda$CDM being the best model for one of them. Adding the Pantheon SnIA dataset with its covariance matrix boosts the statistical preference for $\Lambda$CDM.

    ↳ astro-ph.COgr-qchep-phAstron.Astrophys.(2022)·57 citations
41. 41*

    Relativistic spin hydrodynamics with torsion and linear response theory for spin relaxation

    Masaru Hongo🇺🇸 · Xu-Guang Huang🇨🇳 · Matthias Kaminski🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸

    Using the second law of local thermodynamics and the first-order Palatini formalism, we formulate relativistic spin hydrodynamics for quantum field theories with Dirac fermions, such as QED and QCD, in a torsionful curved background. We work in a regime where spin density, which is assumed to relax much slower than other non-hydrodynamic modes, is treated as an independent degree of freedom in an extended hydrodynamic description. Spin hydrodynamics in our approach contains only three non-hydrodynamic modes corresponding to a spin vector, whose relaxation time is controlled by a new transport coefficient: the rotational viscosity. We study linear response theory and observe an interesting mode mixing phenomenon between the transverse shear and the spin density modes. We propose several field-theoretical ways to compute the spin relaxation time and the rotational viscosity, via the Green-Kubo formula based on retarded correlation functions.

    ↳ hep-thcond-mat.mes-hallcond-mat.stat-mechhep-ph+1JHEP(2021)·162 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.