HEP Phenomenology·hep-ph

Tue·Dec 1, 2020Tuesday·December 1, 2020

43 papers—28 primary·15 cross-listed·reconstructed*

01*
Collider constraints on dark mediators
Hanna Mies🇩🇪 · Christiane Scherb🇩🇪 · Pedro Schwaller🇩🇪
We explore the constraints current collider searches place on a QCD-like dark sector. A combination of multi-jet, multi-jet plus missing energy and emerging jets searches is used to derive constraints on the mediator mass across the full range of the dark meson lifetimes for the first time. The dark sector inherits a flavour structure from the coupling between the dark quarks and the SM quarks through the mediator. When this is taken into account, the differently flavoured dark pions become distinguishable through their lifetime. We show that also in these cases the above mentioned searches remain sensitive, and we obtain limits on the mediator mass also for the flavoured scenario. We then contrast the constraints from collider searches with direct detection bounds on the dark matter candidate itself in both the flavoured and unflavoured scenario. Using a simple prescription it becomes possible to display all constraints in the dark matter and mediator mass plane. Constraints from direct detection tend to be stronger than the collider constraints, unless the coupling to the first generation quarks is suppressed, in which case the collider searches place the most stringent limits on the parameter space.
hep-phhep-exJHEP(2021)·26 citations
02*
Higgs decay into two leptons and a photon revisited
Aliaksei Kachanovich🇩🇪
I present new results for the Standard-Model predictions of the differential decay rates for $H \to ℓ^{+} ℓ^{-} γ$ , where $ℓ = e, μ$ , and the forward-backward asymmetries defined in terms of the flight direction of the photon corresponding to the lepton momenta. The results dependend on the cuts on energies and invariant masses of the final state particles. For standard choices of these cuts the branching ratios $B (H \to e e ˉ γ) = 5.8 \cdot 1 0^{- 5}$ and $B (H \to μ μ ˉ γ) = 6.4 \cdot 1 0^{- 5}$ as well as the forward-backward asymmetries $A_{FB}^{(e)} = 0.343$ and $A_{FB}^{(μ)} = 0.255$ have been found.
hep-phPoS(2021)·0 citations
03*
Form Factors of the Nucleon Axial Current
Chen Chen🇩🇪 · Christian S. Fischer🇩🇪 · Craig D. Roberts🇨🇳 · Jorge Segovia🇪🇸
A symmetry-preserving Poincaré-covariant quark+diquark Faddeev equation treatment of the nucleon is used to deliver parameter-free predictions for the nucleon's axial and induced pseudoscalar form factors, $G_{A}$ and $G_{P}$ , respectively. The result for $G_{A}$ can reliably be represented by a dipole form factor characterised by an axial charge $g_{A} = G_{A} (0) = 1.25 (3)$ and a mass-scale $M_{A} = 1.23 (3) m_{N}$ , where $m_{N}$ is the nucleon mass; and regarding $G_{P}$ , the induced pseudoscalar charge $g_{p}^{*} = 8.80 (23)$ , the ratio $g_{p}^{*} / g_{A} = 7.04 (22)$ , and the pion pole dominance Ansatz is found to provide a reliable estimate of the directly computed result. The ratio of flavour-separated quark axial charges is also calculated: $g_{A}^{d} / g_{A}^{u} = - 0.16 (2)$ . This value expresses a marked suppression of the size of the $d$ -quark component relative to that found in nonrelativistic quark models and owes to the presence of strong diquark correlations in the nucleon Faddeev wave function -- both scalar and axial-vector, with the scalar diquark being dominant. The predicted form for $G_{A}$ should provide a sound foundation for analyses of the neutrino-nucleus and antineutrino-nucleus cross-sections that are relevant to modern accelerator neutrino experiments.
hep-phhep-exhep-latnucl-ex+1PLB(2021)·32 citations
04*
Infrared Renormalons in Kinematic Distributions for Hadron Collider Processes
Silvia Ferrario Ravasio🇬🇧 · Giovanni Limatola🇮🇹 · Paolo Nason🇮🇹
Infrared renormalons in Quantum Chromodynamics are associated with non-perturbative corrections to short distance observables. Linear renormalons, i.e. such that the associated non-perturbative corrections scale like one inverse power of the hard scale, can affect at a non-negligible level even the very high-energy phenomena studied at the Large Hadron Collider. Using an Abelian model, we study the presence of linear renormalons in the transverse momentum distribution of a neutral vector boson $Z$ produced in hadronic collisions. We consider a process where the $Z$ transverse momentum is balanced by a sizable recoil against a coloured final state particle. One may worry that such a colour configuration, not being azimuthally symmetric, could generate unbalanced soft radiation, associated in turn with linear infrared renormalons affecting the transverse momentum distribution of the vector boson. We performed a numerical calculation of the renormalon effects for this process in the so-called large $b_{0}$ limit. We found no evidence of linear renormalons in the transverse momentum distribution of the $Z$ in the large transverse-momentum region, irrespective of rapidity cuts.
hep-phJHEP(2021)·16 citations
05*
Non-standard interactions in SMEFT confronted with terrestrial neutrino experiments
Yong Du🇨🇳 · Hao-Lin Li🇨🇳 · Jian Tang🇨🇳 · Sampsa Vihonen🇨🇳 · Jiang-Hao Yu🇨🇳
The Standard Model Effective Field Theory (SMEFT) provides a systematic and model-independent framework to study neutrino non-standard interactions (NSIs). We study the constraining power of the on-going neutrino oscillation experiments T2K, NO $ν$ A, Daya Bay, Double Chooz and RENO in the SMEFT framework. A full consideration of matching is provided between different effective field theories and the renormalization group running at different scales, filling the gap between the low-energy neutrino oscillation experiments and SMEFT at the UV scale. We first illustrate our method with a top-down approach in a simplified scalar leptoquark model, showing more stringent constraints from the neutrino oscillation experiments compared to collider studies. We then provide a bottom-up study on individual dimension-6 SMEFT operators and find NSIs in neutrino experiments already sensitive to new physics at $\sim$ 20 TeV when the Wilson coefficients are fixed at unity. We also investigate the correlation among multiple operators at the UV scale and find it could change the constraints on SMEFT operators by several orders of magnitude compared with when only one operator is considered. Furthermore, we find that accelerator and reactor neutrino experiments are sensitive to different SMEFT operators, which highlights the complementarity of the two experiment types.
hep-phhep-exJHEP(2021)·21 citations
06*
Prediction of hidden-charm pentaquarks with double strangeness
Fu-Lai Wang🇨🇳 · Rui Chen🇨🇳 · Xiang Liu🇨🇳
Inspired by the recent evidence of $P_{cs} (4459)$ reported by LHCb, we continue to perform the investigation of hidden-charm molecular pentaquarks with double strangeness, which are composed of an $S$ -wave charmed baryon $Ξ_{c}^{(', *)}$ and an $S$ -wave anti-charmed-strange meson $D ˉ_{s}^{(*)}$ . Both the $S$ - $D$ wave mixing effect and the coupled channel effect are taken into account in realistic calculation. A dynamics calculation shows that there may exist two types of hidden-charm molecular pentaquark with double strangeness, i.e., the $Ξ_{c}^{*} D ˉ_{s}^{*}$ molecular state with $J^{P} = 5 / 2^{-}$ and the $Ξ_{c}^{'} D ˉ_{s}^{*}$ molecular state with $J^{P} = 3 / 2^{-}$ . According to this result, we strongly suggest the experimental exploration of hidden-charm molecular pentaquarks with double strangeness. Facing such opportunity, obviously the LHCb will have great potential to hunt for them, with the data accumulation at Run III and after High-Luminosity-LHC upgrade.
hep-phhep-exPRD(2021)·49 citations
07*
$D ˉ_{s}^{(*)} D^{(*)}$ molecular state with $J^{P} = 1^{+}$
Yong-Jiang Xu🇨🇳 · Yong-Lu Liu🇨🇳 · Chun-Yu Cui🇨🇳 · Ming-Qiu Huang🇨🇳
In this paper, we construct $D ˉ_{s}^{(*)} D^{(*)}$ -molecule-type interpolating currents $J_{(\pm) μ} (x)$ with $J^{P} = 1^{+}$ , calculate the corresponding mass and magnetic moment using the QCD sum rule method and its extension in the weak electromagnetic field, and study the processes of $Z_{(\pm) cs}$ to $η_{c} K^{*}$ , $J / ψ K$ , $D ˉ D_{s}^{*}$ , and $D ˉ^{*} D_{s}$ via three-point sum rules. The numerical values are $m_{Z_{(\pm) cs}} = 3.9 9_{- 0.14}^{+ 0.17} \mbox G e V$ , and $λ_{Z_{(\pm) cs}} = 2.0 7_{- 0.16}^{+ 0.28} \times 1 0^{- 2} \mbox G e V^{5}$ , $μ_{Z_{(\pm) cs}} = 0.1 8_{- 0.09}^{+ 0.16} μ_{N}$ with $μ_{N}$ the nucleon magneton, $Γ_{Z_{(+) cs}} = 17.4 7_{- 8.08}^{+ 12.70}$ , and $Γ_{Z_{(-) cs}} = 13.8 6_{- 6.51}^{+ 10.37}$ . The masses are in agreement with the recently measured value of $Z_{cs} (3985)$ by the BESIII Collaboration, $m_{Z_{cs}}^{e x p} = (3982. 5_{- 2.6}^{+ 1.8} \pm 2.1) \mbox M e V$ . The widths are compatible with the experimental value, $Γ_{Z_{cs}}^{e x p} = (12. 8_{- 4.4}^{+ 5.3} \pm 3.0) \mbox M e V$ . The magnetic moment and the various decay modes can help us to determine the inner structure of $Z_{cs} (3985)$ when being confronted with experimental data in the future.
hep-phPRD(2021)·41 citations
08*
Charged-particle multiplicity dependence of charm-baryon-to-meson ratio in high-energy proton-proton collisions
Yu Chen🇨🇳 · Min He🇨🇳
We propose that the charged-particle multiplicity dependence of the charm-baryon-to-meson ratio observed in high-energy $pp$ collisions can be explained by canonical treatment of quantum charges in the statistical hadronization model (SHM). Taking the full particle listings of PDG complemented by additional charm-baryon states from relativistic quark model predictions, we evaluate the canonical partition function and the charm-hadron chemical factors that measure the canonical suppression arising from the requirement of strict conservation of quantum charges. We demonstrate that, while charm number conservation induces common suppression on the production of both charm-baryons and -mesons, baryon (strangeness) number conservation causes further suppression on charm-baryons (charm-strange mesons) relative to nonstrange charm-mesons, thereby resulting in a decreasing $Λ_{c} / D^{0}$ ( $D_{s} / D^{0}$ ) ratio toward smaller multiplicity events. The charm-hadron thermal densities thus computed are then used as pertinent weights to perform charm-quark fragmentation simulations yielding $p_{T}$ -dependent $Λ_{c} / D^{0}$ and $D_{s} / D^{0}$ ratios at varying multiplicities in fair agreement with ALICE measurements.
hep-phhep-exnucl-exnucl-thPLB(2021)·25 citations
09*
Bjorken variable and scale dependence of quark transport coefficient in semi-inclusive lepton-production of hadron off nuclei
Tian-Xing Bai🇨🇳 · Chun-Gui Duan🇨🇳
Nuclear modification of hadron production in deep inelastic lepton-nucleus scattering can be applied to study the parton propagation mechanism in cold nuclear matter. By means of the analytic parameterization of quenching weight based on BDMPS formalism with the target nuclear geometry effect, the leading-order computations for hadron multiplicity ratios are performed with comparison to the HERMES charged pions production data on the quarks hadronization occurring outside the nucleus. The relation is discovered between quark transport coefficient and the measurable kinematic variables in deep inelastic scattering. Four models are proposed on the quark transport coefficient. The constant model, the power-law model and the double power-law model can be ruled out because of the experimental fact that the transverse momentum broadening increases as a function of the photon virtuality $Q^{2}$ . The quark transport coefficient is determined as a function of the Bjorken variable $x$ and scale $Q^{2}$ . The trend of quark transport coefficient in respect of Bjorken variable $x$ and scale $Q^{2}$ is qualitatively in partial agreement with HERMES experimental data on transverse momentum broadening. It is hoped that our effort is conducive to understanding of jet quenching phenomenon in relativistic heavy ion collisions.
hep-phEur.Phys.J.Plus(2021)·4 citations
10*
Representation of fermions in the Pati-Salam model
De-Sheng Li
In this paper, a representation of fermions in the Pati-Salam model is suggested. The semi-leptonic and beyond standard model flavor changing neutral currents of the Lagrangian in this representation of fermions are discussed. A pair of possible Cabibbo-Kobayashi-Maskawa and Pontecorvo-Maki-Nakagawa-Sakata matrices are defined. An effective Lagrangian for this model is given.
hep-phhep-thLHEP(2024)·2 citations
11*
Explaining the Many Threshold Structures in the Heavy-Quark Hadron Spectrum
Xiang-Kun Dong🇨🇳 · Feng-Kun Guo🇨🇳 · Bing-Song Zou🇨🇳
Tremendous progress has been made experimentally in the hadron spectrum containing heavy quarks in the last two decades. It is surprising that many resonant structures are around thresholds of a pair of heavy hadrons. There should be a threshold cusp at any $S$ -wave threshold. By constructing a nonrelativistic effective field theory with open channels, we discuss the generalities of threshold behavior, and offer an explanation of the abundance of near-threshold peaks in the heavy quarkonium regime. We show that the threshold cusp can show up as a peak only for channels with attractive interaction, and the width of the cusp is inversely proportional to the reduced mass relevant for the threshold. We argue that there should be threshold structures at any threshold of a pair of heavy-quark and heavy-antiquark hadrons, which have attractive interaction at threshold, in the invariant mass distribution of a heavy quarkonium and light hadrons that couple to that open-flavor hadron pair. The structure becomes more pronounced if there is a near-threshold pole. Predictions of the possible pairs are also given for the ground state heavy hadrons. Precisely measuring the threshold structures will play an important role in revealing the heavy-hadron interactions, and thus understanding the puzzling hidden-charm and hidden-bottom structures.
hep-phhep-exhep-latnucl-thPRL(2021)·165 citations
12*
Parton Interpretation and Twist-4 Parton Distributions
J.P. Ma🇨🇳 · Z.Y. Pang🇨🇳 · G.P. Zhang🇨🇳
Through explicit examples we show that twist-4 parton distributions have no parton interpretation in the sense that parton or partons inside a hadron can carry the momentum fraction $x$ of the hadron with $x > 1$ or $x < - 1$ . The studied twist-4 parton distributions of collinear factoization are power-divergent for $∣ x ∣ > 1$ . The corresponding transverse momentum dependent parton distributions have also no parton interpretation. They are finite. The implications of our results are discussed.
hep-phPLB(2021)·0 citations
13*
Detecting the pure triangle sigularity effect through the $ψ (2 S) \to p p ˉ η / p p ˉ π^{0}$ process
Qi Huang🇨🇳 · Chao-Wei Shen🇨🇳 · Jia-Jun Wu🇨🇳
In this work, the triangle singularity mechanism is investigated in the $ψ (2 S) \to p p ˉ η / p p ˉ π^{0}$ process. The triangle loop composed by $J / ψ$ , $η$ and $p$ has a singularity in the physical kinematic range for the $ψ (2 S) \to p p ˉ η / p p ˉ π^{0}$ process, and it would generate a very narrow peak in the invariant mass spectrum of $p η (π)$ around $1.56387$ GeV, which is far away from both the threshold and relative resonances. In these processes, all the involved vertices are constrained by the experimental data. Thus, we can make a precise model independent prediction here. It turns out that the peak in the $p η$ invariant mass spectrum is visible, while it is very small in the $p π^{0}$ invariant mass spectrum. We expect this effect shown in $p p ˉ η$ final state can be observed by the Beijing Spectrometer (BESIII) and Super Tau-Charm Facility (STCF) in the future.
hep-phPRD(2021)·12 citations
14*
Calculation of the one loop box integral at Finite Temperature and Density
A. S. Khvorostukhin🇷🇺
Calculation of hadronization, decay or scattering processes at non-zero temperatures and densities within the Nambu-Jona-Lasinio-like models requires some techniques for computation of Feynmann diagrams. Decomposition of Feynman diagrams at the one loop level leads to the appearance of elementary integrals with one, two, three, and four fermion lines. For example, evaluation of the $π π$ scattering amplitude requires calculating a box diagram with four fermion lines. In this work, the real and imaginary parts of the box integral at the one loop level are provided in the form suitable for numerical evaluation. The obtained expressions are applicable to any value of temperature, particle mass, and chemical potential. We pay special attention to the conditions for the existence of the appearing improper integrals and correct the results \cite{Klevansky} for the three fermion lines. As a result, we have obtained constraints on possible values of particle momenta. Among the expressions for the box integral, the general formulas for the integral with an arbitrary number of lines are derived for the case with zero or collinear fermion momenta.
hep-phActa Phys.Polon.B(2021)·2 citations
15*
New physics in $b \to s e^{+} e^{-}$ : A model independent analysis
Ashutosh Kumar Alok🇮🇳 · Suman Kumbhakar🇮🇳 · Jyoti Saini🇮🇳 · S Uma Sankar🇮🇳
The lepton universality violating flavor ratios $R_{K} / R_{K^{*}}$ indicate new physics either in $b \to s μ^{+} μ^{-}$ or in $b \to s e^{+} e^{-}$ or in both. If the new physics is only $b \to s e^{+} e^{-}$ transition, the corresponding new physics operators, in principle, can have any Lorentz structure. In this work, we perform a model independent analysis of new physics only in $b \to s e^{+} e^{-}$ decay by considering effective operators either one at a time or two similar operators at a time. We include all the measurements in $b \to s e^{+} e^{-}$ sector along with $R_{K} / R_{K^{*}}$ in our analysis. We show that various new physics scenarios with vector/axial-vector operators can account for $R_{K} / R_{K^{*}}$ data but those with scalar/pseudoscalar operators and with tensor operators can not. We also show that the azimuthal angular observable $P_{1}$ in $B \to K^{*} e^{+} e^{-}$ decay is most suited to discriminate between the different allowed solutions.
hep-phhep-exNPB(2021)·4 citations
16*
Riemann $ζ (4)$ function contributions to $O (α_{s}^{5})$ terms of Adler D-function and Bjorken polarized sum rule in $S U (N_{c})$ QCD: results and consequences
I.O. Goriachuk🇷🇺 · A. L. Kataev🇷🇺
Two renormalization group invariant quantities in quantum chromodinamics (QCD), defined in Euclidean space,namely, Adler D-function of electron-positron annihilation to hadrons and Bjorken polarized deep-inelastic scattering sum rule, are considered. It is shown, that the 5-th order corrections to them in $M S$ -like renormalization prescriptions, proportional to Riemann $ζ$ -function $ζ (4)$ , can be restored by the transition to the C-scheme, with the $β$ -function, analogous to Novikov, Shifman, Vainshtein and Zakharov exact $β$ -function in $N = 1$ supersymmetric gauge theories. The general analytical expression for these corrections in $S U (N_{c})$ QCD is deduced and their scale invariance is shown. The $β$ -expansion procedure for these contributions is performed and mutual cancellation of them in the 5-th order of the generalized Crewther identity are discussed.
hep-phhep-th3 citations
17*
Decay: A Monte Carlo library for the decay of a particle with ROOT compatibility
R.A. Kycia🇨🇿 · P. Lebiedowicz🇵🇱 · A. Szczurek🇵🇱
Recently, there is a need for a general-purpose event generator of decays of an elementary particle or a hadron to a state of higher multiplicity ( $N > 2$ ) that is simple to use and universal. We present the structure of such a library to produce generators that generate kinematics of decay processes and can be used to integrate any matrix element squared over phase space of this decay. Some test examples are presented, and results are compared with results known from the literature. As one of examples we consider the Standard Model Higgs boson decay into four leptons. The generators discussed here are compatible with the ROOT interface.
hep-phcs.CEhep-thnucl-thCommun.Comput.Phys.(2021)·2 citations
18*
Non-perturbative Effects on Electroweakly Interacting Massive Particles at Hadron Collider
Taisuke Katayose🇯🇵 · Shigeki Matsumoto🇯🇵 · Satoshi Shirai🇯🇵
Electroweakly Interacting Massive Particles (EWIMPs), in other words, new massive particles that are charged under the electroweak interaction of the Standard Model (SM), are often predicted in various new physics models. EWIMPs are probed at hadron collider experiments not only by observing their direct productions but also by measuring their quantum effects on Drell-Yan processes for SM lepton pair productions. Such effects are known to be enhanced especially when the di-lepton invariant mass of the final state is close to the EWIMP threshold, namely twice the EWIMP mass. In such a mass region, however, we have to carefully take non-perturbative effects into account, because the EWIMPs become non-relativistic and the prediction may be significantly affected by e.g., bound states of the EWIMPs caused by the electroweak interaction. We study such non-perturbative effects using the non-relativistic effective field theory of the EWIMPs, and found that those indeed affect the differential cross section of the Drell-Yan processes significantly, though the effects are smeared due to the finite energy resolution of the lepton measurement at the Large Hadron Collider experiment.
hep-phhep-exPRD(2021)·7 citations
19*
Reheating and Dark Matter Production
Marcos A. G. Garcia🇪🇸
A concise summary of out-of-equilibrium dark matter production during post-inflationary reheating is presented. We show that the dark matter relic abundance is in general sensitive to the thermalization rate of the inflaton decay products, and the evolution of the temperature of the subsequently thermalized radiation. We discuss how smoking-gun signals, such as monochromatic neutrinos or gamma-ray lines, or Lyman- $α$ data, can help constrain out-of-equilibrium DM models.
hep-phAstron.Nachr.(2021)·0 citations
20*
Birefringence of electromagnetic waves in the relic neutrino gas
Maxim Dvornikov🇷🇺 · Victor B. Semikoz (IZMIRAN)🇷🇺
We reconsider the problem of the birefringence of electromagnetic (EM) waves in a medium consisting of a plasma and a $ν ν ˉ$ -gas within the Standard Model of particle physics. The considered effect arises in such a medium due to the parity violation for the electroweak neutrino-electron interaction. Our recent calculations of the electroweak correction to the photon polarization operator in the electroweak plasma allow us to significantly improve some previous estimates of such effect in astrophysics. We estimate the rotary power for EM waves propagating in a non-relativistic plasma in the intergalactic space and interacting with the gas of relic neutrinos and antineutrinos there. We show that, in presence of a plasma, the EM wave birefringence effect in a $ν ν ˉ$ -gas exceeds significantly that effect in a $ν ν ˉ$ -gas in empty space considered earlier. These previous treatments of the birefringence relied on the calculations of the refraction index for on-shell photons in vacuum using the forward scattering amplitude $γ ν \to γ ν$ with virtual charged leptons in Feynman diagrams. The possibility to observe experimentally the new effect suggested here is discussed.
hep-phastro-ph.COJCAP(2021)·5 citations
21*
Charged and neutral Higgs bosons in final states with six bottom quarks
Radovan Dermisek🇺🇸 · Enrico Lunghi🇺🇸 · Navin McGinnis🇺🇸 · Seodong Shin🇰🇷
In extensions of two Higgs doublet models with vectorlike quarks, the decays of vectorlike quarks may be easily dominated by cascade decays through charged or neutral Higgs bosons leading to signatures with 6 top or bottom quarks. Since top quark decays also contain bottom quarks, the 6 bottom quarks in final states is a common signature to a large class of possible decay chains. We present a search strategy focusing on this final state and find the mass ranges of vectorlike quarks and Higgs bosons that can be explored at the Large Hadron Collider. Among other results the sensitivity to the charged Higgs boson, extending above 2 TeV, stands out when compared to models without vectorlike matter.
hep-phhep-exPoS(2021)·0 citations
22*
Employing nucleon decay as a fingerprint of SUSY GUT models using \texttt{SusyTCProton}
Stefan Antusch🇨🇭 · Christian Hohl🇨🇭 · Vasja Susič🇨🇭
While the observation of nucleon decay would be a smoking gun of Grand Unified Theories (GUTs) in general, the ratios between the decay rates of the various channels carry rich information about the specific GUT model realization. To investigate this fingerprint of GUT models in the context of supersymmetric (SUSY) GUTs, we present the software tool \texttt{SusyTCProton}, which is an extension of the module \texttt{SusyTC} to be used with the \texttt{REAP} package. It allows to calculate nucleon decay rates from the relevant dimension five GUT operators specified at the GUT scale, including the full loop-dressing at the SUSY scale. As an application, we investigate the fingerprints of two example GUT toy models with different flavor structures, performing an MCMC analysis to include the experimental uncertainties for the charged fermion masses and CKM mixing parameters. While both toy models provide equally good fits to the low energy data, we show how they could be distinguished via their predictions of ratios for nucleon decay rates. Together with \texttt{SusyTCProton} we also make the additional module \texttt{ProtonDecay} public. It can be used independently from \texttt{REAP} and allows to calculate nucleon decay rates from given $D = 5$ and $D = 6$ operator coefficients (accepting the required SUSY input for the $D = 5$ case in SLHA format). The $D = 6$ functionality can also be used to calculate nucleon decay in non-SUSY GUTs.
hep-phJHEP(2021)·14 citations
23*
Probing four-fermion operators in the triple top production at future hadron colliders
Sara Khatibi🇮🇷 · Hamzeh Khanpour🇮🇷
In this paper, we study the triple top quark production at the future high-energy proton-proton colliders to probe the four-fermion interactions involving three top quarks. We employ the Standard Model Effective Field Theory (SMEFT) to find the upper limits at $95%$ CL on the Wilson coefficients of these kinds of four-fermion operators. We consider a detailed analysis with a unique signal signature of two same-sign leptons. A full simulation chain includes all the relevant backgrounds, realistic detector simulations and a cut-based technique are taken into account. This study is presented for the HE-LHC working at the center of mass energy of 27 TeV with 15~ab $^{- 1}$ and FCC-hh working at the center of mass energy of 100 TeV with 30~ab $^{- 1}$ . We show that the future high-energy proton-proton colliders could reach an impressive sensitivity to four-fermion contact interactions involving three top quarks.
hep-phNPB(2021)·9 citations
24*
Improvements on dipole shower colour
Jack Holguin🇬🇧 · Jeffrey R. Forshaw🇬🇧 · Simon Plätzer🇦🇹
The dipole formalism provides a powerful framework from which parton showers can be constructed. In a recent paper, we proposed a dipole shower with improved colour accuracy and in this paper we show how it can be further improved. After an explicit check at $O (α_{s}^{2})$ we confirm that our original shower performs as it was designed to, i.e. inheriting its handling of angular-ordered radiation from a coherent branching algorithm. We also show how other dipole shower algorithms fail to achieve this. Nevertheless, there is an $O (α_{s}^{2})$ topology where it differs at sub-leading $N_{c}$ from a coherent branching algorithm. This erroneous topology can contribute a leading logarithm to some observables and corresponds to emissions that are ordered in $k_{t}$ but not angle. We propose a simple, computationally efficient way to correct this and assign colour factors in accordance with the coherence properties of QCD to all orders in $α_{s}$ .
hep-phEPJC(2021)·45 citations
25*
Two-loop helicity amplitudes for $g g \to Z Z$ with full top-quark mass effects
Bakul Agarwal🇺🇸 · Stephen P. Jones🇨🇭 · Andreas von Manteuffel🇺🇸
We calculate the two-loop QCD corrections to $g g \to Z Z$ involving a closed top-quark loop. We present a new method to systematically construct linear combinations of Feynman integrals with a convergent parametric representation, where we also allow for irreducible numerators, higher powers of propagators, dimensionally shifted integrals, and subsector integrals. The amplitude is expressed in terms of such finite integrals by employing syzygies derived with linear algebra and finite field techniques. Evaluating the amplitude using numerical integration, we find agreement with previous expansions in asymptotic limits and provide ab initio results also for intermediate partonic energies and non-central scattering at higher energies.
hep-phhep-thJHEP(2021)·64 citations
26*
Precision QCD phenomenology of exotic spin-2 search at the LHC
Goutam Das🇩🇪 · M. C. Kumar🇮🇳 · Kajal Samanta🇮🇳
The complete next-to-next-to leading order (NNLO) QCD correction matched with next-to-next-to leading logarithm (NNLL) has been studied for Drell-Yan production through spin-2 particle at the Large hadron collider (LHC). We consider generic spin-2 particle which couples differently to the quarks and the gluons (non-universal scenario). The threshold enhanced analytical coefficient has been obtained up to third order exploiting the universality of the soft function as well as the process dependent form factors at the same order. We performed a detailed phenomenological analysis and give prediction for the 13 TeV LHC for the search of such BSM signature. We found that the matched correction at the second order gives sizeable corrections over wide range of invariant mass of the lepton pair. The scale variation also stabilizes at this order and reduces to 4%. As a by-product we also provide ingredients for third order soft-virtual (SV) prediction as well as resummation and study the impact on LHC searches.
hep-phJHEP(2021)·9 citations
27*
Small instantons and the strong CP problem in composite Higgs models
R.S. Gupta🇬🇧 · V.V. Khoze🇬🇧 · M. Spannowsky🇬🇧
We show that QCD instantons can generate large effects at small length scales in the ultraviolet in standard composite Higgs models that utilise partial compositeness. This has important implications for possible solutions of the strong CP problem in these models. First we show that in the simplest known UV completions of composite Higgs models, if an axion is also present, it can have a mass much larger than the usual QCD axion. Even more remarkable is the case where there are no axions, but the strong CP problem can be solved by generating the up quark mass entirely from the contribution of instantons thus reviving the massless up-quark solution for these models. In both cases no additional field content is required apart from what is required to realise partial compositeness.
hep-phhep-thPRD(2021)·24 citations
28*
Chiral symmetry breaking and confinement: separating the scales
Nick Evans🇬🇧 · Konstantinos S. Rigatos🇬🇧
We review arguments that chiral symmetry breaking is triggered when the quark bilinear condensate's dimension passes through one ( $γ = 1$ ). This is supported by gap equations and more recently holographic models. Confinement may then be a separate property of the pure Yang-Mills theory below the scale of the dynamically generated quark mass, occurring at the scale of the pole in the deep IR running. Here, we use perturbative results for the running of the gauge coupling and $γ$ in asymptotically free SU( $N_{c}$ ) gauge theories with matter in higher dimension representations to seek the best candidate theories where confinement and chiral symmetry breaking can be maximally separated. For example, SU(2) gauge theory with a single Weyl quark in the $S_{3}$ (dimension 4) representation may have a factor of 20 separation in scale. Such a theory could be simulated on the lattice to test the separation. We also propose studying multi-representation theories where the higher dimension representation forms a condensate at one scale that can be quite separate from the condensation scale of the second representation matter. The confinement scale would presumably be below the second scale. For example, SU(3) gauge theory with a Weyl adjoint fermion and ten fundamental quarks may have a separation of a factor of 20 also.
hep-phhep-lathep-thPRD(2021)·21 citations
29*
Thermal order in large N conformal gauge theories
Soumyadeep Chaudhuri🇮🇱 · Changha Choi🇺🇸 · Eliezer Rabinovici🇮🇱
In this work we explore the possibility of spontaneous breaking of global symmetries at all nonzero temperatures for conformal field theories (CFTs) in $D = 4$ space-time dimensions. We show that such a symmetry-breaking indeed occurs in certain families of non-supersymmetric large $N$ gauge theories at a planar limit. We also show that this phenomenon is accompanied by the system remaining in a persistent Brout-Englert-Higgs (BEH) phase at any temperature. These analyses are motivated by the work done in arXiv:2005.03676 where symmetry-breaking was observed in all thermal states for certain CFTs in fractional dimensions. In our case, the theories demonstrating the above features have gauge groups which are specific products of $S O (N)$ in one family and $S U (N)$ in the other. Working in a perturbative regime at the $N \to \infty$ limit, we show that the beta functions in these theories yield circles of fixed points in the space of couplings. We explicitly check this structure up to two loops and then present a proof of its survival under all loop corrections. We show that under certain conditions, an interval on this circle of fixed points demonstrates both the spontaneous breaking of a global symmetry as well as a persistent BEH phase at all nonzero temperatures. The broken global symmetry is $Z_{2}$ in one family of theories and $U (1)$ in the other. The corresponding order parameters are expectation values of the determinants of bifundamental scalar fields in these theories. We characterize these symmetries as baryon-like symmetries in the respective models.
↳ hep-thcond-mat.str-elhep-phJHEP(2021)·27 citations
30*
$η$ mesons in hot and dense asymmetric nuclear matter
Rajesh Kumar🇮🇳 · Arvind Kumar🇮🇳
We study the $η N$ interactions in the hot and dense isospin asymmetric nuclear matter using two different approaches. In the first approach, the in-medium mass and optical potential of $η$ -meson have been calculated in the chiral SU(3) model, considering the effect of explicit symmetry breaking term and range terms in the $η N$ interaction Lagrangian density. In the second scenario, the conjunction of chiral perturbation theory and chiral SU(3) model is employed. In this case, the next-to-leading order $η N$ interactions are evaluated from the chiral perturbation theory (ChPT), and the in-medium contribution of scalar densities are taken as input from chiral SU(3) model. We observe a larger negative mass-shift in the ChPT+chiral model approach compared to the chiral SU(3) model alone as a function of nuclear density. Moreover, the increase in the asymmetry and temperature cause a decrease in the magnitude of mass-shift. We have also studied the impact of $η N$ scattering length $a^{η N}$ on the $η$ meson mass $m_{η}^{*}$ and observed that the $m_{η}^{*}$ decrease more for increasing the value of scattering length.
↳ nucl-thhep-phPRC(2020)·8 citations
31*
Finite-volume energy shift of the three-pion ground state
Fabian Müller (U. Bonn, HISKP, BCTP)🇩🇪 · Akaki Rusetsky (U. Bonn, HISKP, BCTP and Tbilisi State U.)🇩🇪 · Tiansu Yu (U. Bonn, HISKP, BCTP)🇩🇪
Using the framework of non-relativistic effective field theory, the finite-volume ground-state energy shift is calculated up-to-and-including $O (L^{- 6})$ for the system of three pions in the channel with the total isospin $I = 1$ . The relativistic corrections are included perturbatively, up to the same order in the inverse of the box size $L$ . The obtained explicit expression, together with the known result for the system with maximal isospin $I = 3$ , can be used for the extraction of two independent effective three-body couplings from the measured ground-state spectrum of three pions.
↳ hep-lathep-phPRD(2021)·51 citations
32*
Confinement and moduli locking of Alice strings and monopoles
Muneto Nitta🇯🇵
We argue that strings (vortices) and monopoles are confined, when fields receiving nontrivial Aharonov-Bohm (AB) phases around a string develop vacuum expectation values (VEVs). We illustrate this in an $S U (2) \times U (1)$ gauge theory with charged triplet complex scalar fields admitting Alice strings and monopoles, by introducing charged doublet scalar fields receiving nontrivial AB phases around the Alice string. The Alice string carries a half $U (1)$ magnetic flux and $1/4$ $S U (2)$ magnetic flux taking a value in two of the $S U (2)$ generators characterizing the $U (1)$ modulus. This string is not confined in the absence of a doublet VEV in the sense that the $S U (2)$ magnetic flux can be detected at large distance by an AB phase around the string. When the doublet field develops VEVs, there appear two kinds of phases that we call deconfined and confined phases. When a single Alice string is present in the deconfined phase, the $U (1)$ modulus of the string and the vacuum moduli are locked (the bulk-soliton moduli locking). In the confined phase, the Alice string is inevitably attached by a domain wall that we call an AB defect and is confined with an anti-Alice string or another Alice string with the same $S U (2)$ flux. Depending on the partner, the pair annihilates or forms a stable doubly-wound Alice string having an $S U (2)$ magnetic flux inside the core, whose color cannot be detected at large distance by AB phases, implying the "color" confinement. The theory also admits stable Abrikosov-Nielsen-Olesen string and a $Z_{2}$ string in the absence of the doublet VEVs, and each decays into two Alice strings in the presence of the doublet VEVs. A monopole in this theory can be constructed as a closed Alice string with the $U (1)$ modulus twisted once, and we show that with the doublet VEVs, monopoles are also confined to monopole mesons of the monopole charge two.
↳ hep-thhep-phJHEP(2021)·5 citations
33*
Anharmonic oscillator: a solution
Alexander V Turbiner🇲🇽 · Juan Carlos del Valle🇲🇽
It is shown that for the one-dimensional quantum anharmonic oscillator with potential $V (x) = x^{2} + g^{2} x^{4}$ the Perturbation Theory (PT) in powers of $g^{2}$ (weak coupling regime) and the semiclassical expansion in powers of $ℏ$ for energies coincide. It is related to the fact that the dynamics in $x$ -space and in $(g x)$ -space corresponds to the same energy spectrum with effective coupling constant $ℏ g^{2}$ . Two equations, which govern the dynamics in those two spaces, the Riccati-Bloch (RB) and the Generalized Bloch (GB) equations, respectively, are derived. The PT in $g^{2}$ for the logarithmic derivative of wave function leads to PT (with polynomial in $x$ coefficients) for the RB equation and to the true semiclassical expansion in powers of $ℏ$ for the GB equation, which corresponds to a loop expansion for the density matrix in the path integral formalism. A 2-parametric interpolation of these two expansions leads to a uniform approximation of the wavefunction in $x$ -space with unprecedented accuracy $\sim 1 0^{- 6}$ locally and unprecedented accuracy $\sim 1 0^{- 9} - 1 0^{- 10}$ in energy for any $g^{2} \geq 0$ . A generalization to the radial quartic oscillator is briefly discussed.
↳ quant-phhep-phhep-thmath-ph+2J.Phys.A(2021)·15 citations
34*
Cosmological bound on neutrino masses in the light of $H_{0}$ tension
Toyokazu Sekiguchi🇯🇵 · Tomo Takahashi🇯🇵
Although cosmic microwave background (CMB) is the most powerful cosmological probe of neutrino masses, it is in trouble with local direct measurements of $H_{0}$ , which is called the $H_{0}$ tension. Since neutrino masses are correlated with $H_{0}$ in CMB, one can expect the cosmological bound on neutrino masses would be much affected by the $H_{0}$ tension. We investigate what impact this tension brings to cosmological bound on neutrino masses by assuming a model with modified recombination which has been shown to resolve the tension. We argue that constraints on neutrino masses become significantly weaker in models where the $H_{0}$ tension can be resolved.
↳ astro-ph.COgr-qchep-phhep-thPRD(2021)·18 citations
35*
Vector mesons on the wall
Ryuichiro Kitano🇯🇵 · Ryutaro Matsudo🇯🇵
A domain-wall configuration of the $η^{'}$ meson bounded by a string (called a pancake or a Hall droplet) is recently proposed to describe the baryons with spin $N_{c} /2$ . In order to understand its baryon number as well as the flavor quantum number, we argue that the vector mesons (the $ρ$ and $ω$ mesons) should play an essential role for the consistency of the whole picture. We determine the effective theory of large- $N_{c}$ QCD with $N_{f}$ massless fermions by taking into account a mixed anomaly involving the $θ$ -periodicity and the global symmetry. The anomaly matching requires the presence of a dynamical domain wall on which a $U (N_{f})_{- N_{c}}$ Chern-Simons theory is supported. We consider the boundary conditions that should be imposed on the edge of the domain wall, and conclude that there should be a boundary term that couples the $U (N_{f})_{- N_{c}}$ gauge field to the vector mesons. We discuss the impact on physics of the chiral phase transition and the relation to the "duality" of QCD.
↳ hep-thhep-phJHEP(2021)·23 citations
36*
New cosmological bounds on hot relics: Axions $&$ Neutrinos
William Giarè🇮🇹 · Eleonora Di Valentino🇬🇧 · Alessandro Melchiorri🇮🇹 · Olga Mena🇪🇸
Axions, if realized in nature, can be copiously produced in the early universe via thermal processes, contributing to the mass-energy density of thermal hot relics. In light of the most recent cosmological observations, we analyze two different thermal processes within a realistic mixed hot-dark-matter scenario which includes also massive neutrinos. Considering the axion-gluon thermalization channel we derive our most constraining bounds on the hot relic masses $m_{a} < 7.46$ eV and $\sum m_{ν} < 0.114$ eV both at 95 per cent CL; while studying the axion-pion scattering, without assuming any specific model for the axion-pion interactions and remaining in the range of validity of the chiral perturbation theory, our most constraining bounds are improved to $m_{a} < 0.91$ eV and $\sum m_{ν} < 0.105$ eV, both at 95 per cent CL. Interestingly, in both cases, the total neutrino mass lies very close to the inverted neutrino mass ordering prediction. If future terrestrial double beta decay and/or long baseline neutrino experiments find that the nature mass ordering is the inverted one, this could rule out a wide region in the currently allowed thermal axion window. Our results therefore strongly support multi-messenger searches of axions and neutrino properties, together with joint analyses of their expected sensitivities.
↳ astro-ph.COhep-phMNRAS(2021)·60 citations
37*
Lattice Nucleon Isovector Unpolarized Parton Distribution in the Physical-Continuum Limit
Huey-Wen Lin🇺🇸 · Jiunn-Wei Chen🇹🇼 · Rui Zhang🇺🇸
We present the first lattice-QCD calculation of the nucleon isovector unpolarized parton distribution functions (PDFs) at the physical-continuum limit using Large-Momentum Effective Theory (LaMET). The lattice results are calculated using ensembles with multiple sea pion masses with the lightest one around 135~MeV, 3 lattice spacings $a \in [0.06, 0.12]$ ~fm, and multiple volumes with $M_{π} L$ ranging 3.3 to 5.5. We perform a simultaneous chiral-continuum extrapolation to obtain RI/MOM renormalized nucleon matrix elements with various Wilson-link displacements in the continuum limit at physical pion mass. Then, we apply one-loop perturbative matching to the quasi-PDFs to obtain the lightcone PDFs. We find the lattice-spacing dependence to be much larger than the dependence on pion mass and lattice volume for these LaMET matrix elements. Our physical-continuum limit unpolarized isovector nucleon PDFs are found to be consistent with global-PDF results.
↳ hep-lathep-phnucl-th44 citations
38*
On the physics potential to study the gluon content of proton and deuteron at NICA SPD
A. Arbuzov🇷🇺 · A. Bacchetta🇮🇹 · M. Butenschoen🇩🇪 · F.G. Celiberto🇮🇹 · U. D'Alesio🇮🇹 · M. Deka🇷🇺 · I. Denisenko🇷🇺 · M. G. Echevarria🇪🇸 · A. Efremov🇷🇺 · N.Ya. Ivanov🇷🇺 · A. Guskov🇷🇺 · A. Karpishkov🇷🇺 and 16 other authors
The Spin Physics Detector (SPD) is a future multipurpose experiment foreseen to run at the NICA collider, which is currently under construction at the Joint Institute for Nuclear Research (JINR, Dubna, Russia). The physics program of the experiment is based on collisions of longitudinally and transversely polarized protons and deuterons at $s$ up to 27 GeV and luminosity up to 10 $^{32}$ cm $^{- 2}$ s $^{- 1}$ . The SPD will operate as a universal facility for comprehensive study of unpolarized and polarized gluon content of the nucleon, using different complementary probes such as: charmonia, open charm, and prompt photon production processes. The aim of this work is to make a thorough review of the physics objectives that can potentially be addressed at the SPD, underlining related theoretical aspects and discussing relevant experimental results when available. Among different pertinent phenomena particular attention is drawn to the study of the gluon helicity, gluon Sivers and Boer-Mulders functions in the nucleon, as well as the gluon transversity distribution in the deuteron, via the measurement of specific single and double spin asymmetries.
↳ hep-exhep-phPPNP(2021)·140 citations
39*
Chern-Weil Global Symmetries and How Quantum Gravity Avoids Them
Ben Heidenreich🇺🇸 · Jacob McNamara🇺🇸 · Miguel Montero🇺🇸 · Matthew Reece🇺🇸 · Tom Rudelius🇺🇸 · Irene Valenzuela🇺🇸
We draw attention to a class of generalized global symmetries, which we call "Chern-Weil global symmetries," that arise ubiquitously in gauge theories. The Noether currents of these Chern-Weil global symmetries are given by wedge products of gauge field strengths, such as $F_{2} \land H_{3}$ and $tr (F_{2}^{2})$ , and their conservation follows from Bianchi identities. As a result, they are not easy to break. However, it is widely believed that exact global symmetries are not allowed in a consistent theory of quantum gravity. As a result, any Chern-Weil global symmetry in a low-energy effective field theory must be either broken or gauged when the theory is coupled to gravity. In this paper, we explore the processes by which Chern-Weil symmetries may be broken or gauged in effective field theory and string theory. We will see that many familiar phenomena in string theory, such as axions, Chern-Simons terms, worldvolume degrees of freedom, and branes ending on or dissolving in other branes, can be interpreted as consequences of the absence of Chern-Weil symmetries in quantum gravity, suggesting that they might be general features of quantum gravity. We further discuss implications of breaking and gauging Chern-Weil symmetries for particle phenomenology and for boundary CFTs of AdS bulk theories. Chern-Weil global symmetries thus offer a unified framework for understanding many familiar aspects of quantum field theory and quantum gravity.
↳ hep-thhep-phJHEP(2021)·128 citations
40*
Single-particle digitization strategy for quantum computation of a $ϕ^{4}$ scalar field theory
João Barata🇪🇸 · Niklas Mueller🇺🇸 · Andrey Tarasov🇺🇸 · Raju Venugopalan🇺🇸
Motivated by the parton picture of high energy quantum chromodynamics, we develop a single-particle digitization strategy for the efficient quantum simulation of relativistic scattering processes in a $d + 1$ dimensional scalar $ϕ^{4}$ field theory. We work out quantum algorithms for initial state preparation, time evolution and final state measurements. We outline a non-perturbative renormalization strategy in this single-particle framework.
↳ hep-thhep-phnucl-thquant-phPRA(2021)·85 citations
41*
All-loop-orders relation between Regge limits of $N = 4$ SYM and $N = 8$ supergravity four-point amplitudes
Stephen G. Naculich🇺🇸
We examine in detail the structure of the Regge limit of the (nonplanar) $N = 4$ SYM four-point amplitude. We begin by developing a basis of color factors $C_{ik}$ suitable for the Regge limit of the amplitude at any loop order, and then calculate explicitly the coefficients of the amplitude in that basis through three-loop order using the Regge limit of the full amplitude previously calculated by Henn and Mistlberger. We compute these coefficients exactly at one loop, through $O (ϵ^{2})$ at two loops, and through $O (ϵ^{0})$ at three loops, verifying that the IR-divergent pieces are consistent with (the Regge limit of) the expected infrared divergence structure, including a contribution from the three-loop correction to the dipole formula. We also verify consistency with the IR-finite NLL and NNLL predictions of Caron-Huot et al. Finally we use these results to motivate the conjecture of an all-orders relation between one of the coefficients and the Regge limit of the $N = 8$ supergravity four-point amplitude.
↳ hep-thhep-phJHEP(2021)·8 citations
42*
Two theorems for the gradient expansion of relativistic hydrodynamics
Saulo Diles🇧🇷
This letter is dedicated to providing proof of two statements concerning the gradient expansion of relativistic hydrodynamics. The first statement is that \textit{the ordering of transverse derivatives is irrelevant in the gradient expansion of a non-conformal fluid}. The second statement is that \textit{the longitudinal projection of the Weyl covariant derivative can be eliminated in the gradient expansion of a conformal fluid}. This second statement does not apply to curvature tensors. In the conformal case, we know that the ordering of Weyl covariant derivatives is irrelevant in the gradient expansion.
↳ hep-thgr-qchep-phPLB(2022)·4 citations
43*
The Convex Hull Swampland Distance Conjecture and Bounds on Non-geodesics
José Calderón-Infante🇪🇸 · Angel M. Uranga🇪🇸 · Irene Valenzuela🇺🇸
The Swampland Distance Conjecture (SDC) restricts the geodesic distances that scalars can traverse in effective field theories as they approach points at infinite distance in moduli space. We propose that, when applied to the subset of light fields in effective theories with scalar potentials, the SDC restricts the amount of non-geodesicity allowed for trajectories along valleys of the potential. This is necessary to ensure consistency of the SDC as a valid swampland criterium at any energy scale across the RG flow. We provide a simple description of this effect in moduli space of hyperbolic space type, and products thereof, and obtain critical trajectories which lead to maximum non-geodesicity compatible with the SDC. We recover and generalize these results by expressing the SDC as a new Convex Hull constraint on trajectories, characterizing towers by their scalar charge to mass ratio in analogy to the Scalar Weak Gravity Conjecture. We show that recent results on the asymptotic scalar potential of flux compatifications near infinity in moduli space precisely realize these critical amounts of non-geodesicity. Our results suggest that string theory flux compactifications lead to the most generic potentials allowing for maximum non-geodesicity of the potential valleys while respecting the SDC along them.
↳ hep-thhep-phJHEP(2021)·91 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.