HEP Phenomenology·hep-ph

Tue·Apr 4, 2023Tuesday·April 4, 2023

36 papers—23 primary·13 cross-listed·reconstructed*

01*
On the Role of LHC and HL-LHC in Constraining Flavor Changing Neutral Currents
S. Kovalenko🇨🇱 · A. S. de Jesus🇧🇷 · A. R. Zerwekh🇨🇱 · Y.M. Oviedo-Torres · F. S. Queiroz🇧🇷 · T. B. de Melo🇨🇱 · J. P. Neto🇧🇷 · Y. S. Villamizar🇧🇷
The Standard Model (SM) has no flavor-changing neutral current (FCNC) processes at the tree level. Therefore, processes featuring FCNC in new physics are tightly constrained by data. Typically, the lower bounds on the scale of new physics obtained from $K - K ˉ$ or $B - B ˉ$ mixing lie well above 10 TeV, surpassing the reach of current and future colliders. In this paper, we demonstrate, using a specific Z' model, that such limits can be severely weakened by applying certain parametrizations of the quark mixing matrices with no prejudice while maintaining the CKM matrix in agreement with the data. We highlight the valuable role of the often-overlooked D0 mixing in deriving robust FCNC limits and show that the LHC and HL-LHC are promising probes for flavor-changing interactions mediated by a Z' boson.
hep-phhep-exPLB(2024)·13 citations
02*
Quantum free-streaming: out of equilibrium expansion for the free scalar fields
Leonardo Tinti🇵🇱
The collisionless Boltzmann equation, also called free-streaming, is a convenient approximation. It is rather simple to implement numerically, and and it is effective at reducing the irregularities of rough initial conditions. It can be obtained as a small $ℏ$ limit from a free scalar quantum field. Namely, by neglecting the $ℏ^{2}$ term in the dynamical evolution of the Wigner distribution, the quantum precursor of the distribution function. In this work it is presented the general form for the exact solutions of the Wigner distribution, for a scalar field undergoing a $(1 + 1)$ -dimensional expansion. Namely, with the symmetry constraint of rotation and translation invariance in the transverse plane. It is very different from the (on-shell) free-streaming of classical particles. It is shown how to recognize the classical, $ℏ \to 0$ , limit from the general form. The numerical analysis for a specific example shows very large quantum corrections to the classical free-streaming.
hep-phnucl-thPRD(2023)·7 citations
03*
Effective field theories for dark matter pairs in the early universe: cross sections and widths
Simone Biondini🇨🇭 · Nora Brambilla🇩🇪 · Gramos Qerimi🇩🇪 · Antonio Vairo🇩🇪
In order to predict the cosmological abundance of dark matter, an estimation of particle rates in an expanding thermal environment is needed. For thermal dark matter, the non-relativistic regime sets the stage for the freeze-out of the dark matter energy density. We compute transition widths and annihilation, bound-state formation, and dissociation cross sections of dark matter fermion pairs in the unifying framework of non-relativistic effective field theories at finite temperature, with the thermal bath modeling the thermodynamical behaviour of the early universe. We reproduce and extend some known results for the paradigmatic case of a dark fermion species coupled to dark gauge bosons. The effective field theory framework allows to highlight their range of validity and consistency, and to identify some possible improvements.
hep-phastro-ph.COJHEP(2023)·30 citations
04*
Hadron Structure using Continuum Schwinger Function Methods
Craig D. Roberts🇨🇳
The vast bulk of visible mass emerges from nonperturbative dynamics within quantum chromodynamics (QCD) -- the strong interaction sector of the Standard Model. The past decade has revealed the three pillars that support this emergent hadron mass (EHM); namely, a nonzero gluon mass-scale, a process-independent effective charge, and dressed-quarks with constituent-like masses. Theory is now working to expose their manifold and diverse expressions in hadron observables and highlighting the types of measurements that can be made in order to validate the paradigm. In sketching some of these developments, this discussion stresses the role of EHM in forming nucleon electroweak structure and the wave functions of excited baryons through the generation of dynamical diquark correlations; producing and constraining the dilation of the leading-twist pion distribution amplitude; shaping pion and nucleon parton distribution functions -- valence, glue and sea, including the antisymmetry of antimatter; and moulding pion and proton charge and mass distributions.
hep-phhep-exhep-latnucl-ex+1Few Body Syst.(2023)·10 citations
05*
Parallel Seesaw Mechanisms for Neutrinos and Freeze-In Long-Lived Dark Matter
Ernest Ma (UC Riverside)🇺🇸
If dark matter is light, it may be due to a seesaw mechanism just as neutrinos are. It is postulated that both originate from the same type of heavy fermion anchors, either singlets or triplets. In the latter case, a shift of the $W$ mass is predicted, as suggested by the $C D F$ precision measurement. A spontaneously broken dark $U (1)$ gauge symmetry is assumed, resulting in freeze-in long-lived light dark matter.
hep-phPLB(2023)·0 citations
06*
Study of new physics effects in $B ˉ_{s} \to D_{s}^{(*)} τ^{-} ν ˉ_{τ}$ semileptonic decays using lattice QCD form factors and heavy quark effective theory
Neus Penalva🇪🇸 · Jonathan M. Flynn🇬🇧 · Eliecer Hernández🇪🇸 · Juan Nieves🇪🇸
We benefit from the lattice QCD determination by the HPQCD of the Standard Model (SM) form factors for the $B ˉ_{s} \to D_{s}$ [Phys. Rev. D 101, 074513 (2020)] and the SM and tensor ones for the $B ˉ_{s} \to D_{s}^{*}$ (arXiv:2304.03137 [hep-lat]) semileptonic decays, and the heavy quark effective theory (HQET) relations for the analogous $B \to D^{(*)}$ decays obtained by F.U. Bernlochner et al. in Phys. Rev. D 95, 115008 (2017), to extract the leading and sub-leading Isgur-Wise functions for the $B ˉ_{s} \to D_{s}^{(*)}$ decays. Further use of the HQET relations allows us to evaluate the corresponding scalar, pseudoscalar and tensor form factors needed for a phenomenological study of new physics (NP) effects on the $B ˉ_{s} \to D_{s}^{(*)}$ semileptonic decay. At present, the experimental values for the ratios $R_{D^{(*)}} = Γ [B ˉ \to D^{(*)} τ^{-} ν ˉ_{τ}] /Γ [B ˉ \to D^{(*)} e^{-} (μ^{-}) ν ˉ_{e (μ)}]$ are the best signal in favor of lepton flavor universality violation (LFUV) seen in charged current (CC) $b \to c$ decays. In this work we conduct a study of NP effects on the $B ˉ_{s} \to D_{s}^{(*)} τ^{-} ν ˉ_{τ}$ semileptonic decays by comparing tau spin, angular and spin-angular asymmetry distributions obtained within the SM and three different NP scenarios. As expected from SU(3) light-flavor symmetry, we get results close to the ones found in a similar analysis of the $B ˉ \to D^{(*)}$ case. The measurement of the $B ˉ_{s} \to D_{s}^{(*)} ℓ ν ˉ_{ℓ}$ semileptonic decays, which is within reach of present experiments, could then be of relevance in helping to establish or rule out LFUV in CC $b \to c$ transitions.
hep-phhep-latJHEP(2024)·11 citations
07*
Investigation of proton structure function $F_{2}^{p}$ at HERA in light of an analytical solution to Balitsky-Kovchegov equation
Ranjan Saikia🇮🇳 · Pragyan Phukan🇮🇳 · Jayanta Kumar Sarma🇮🇳
In this paper, the proton structure function $F_{2}^{p} (x, Q^{2})$ at small- $x$ is investigated using an analytical solution of the Balitsky-Kovchegov (BK) equation. In the context of the color dipole description of deep inelastic scattering (DIS), the structure function $F_{2}^{p} (x, Q^{2})$ is computed by applying the analytical expression for the scattering amplitude $N (k, Y)$ derived from the BK solution. At transverse momentum $k$ and total rapidity $Y$ , the scattering amplitude $N (k, Y)$ represents the propagation of the quark-antiquark dipole in the color dipole description of DIS. Using the BK solution we extracted the integrated gluon density $xg (x, Q^{2})$ and then compared our theoretical estimation with the LHAPDF global data fits NNPDF3.1sx and CT18. Finally, we investigated the behavior of $F_{2}^{p} (x, Q^{2})$ in the kinematic region of $1 0^{- 5} \leq x \leq 1 0^{- 2}$ and $2.5$ $G e V^{2}$ $\leq$ $Q^{2}$ $\leq$ $60$ $G e V^{2}$ . Our predicted results for $F_{2}^{p} (x, Q^{2})$ within the specified kinematic region are in good agreement with the recent high-precision data for $F_{2}^{p} (x, Q^{2})$ from HERA (H1 Collaboration) and the LHAPDF global parametrization group NNPDF3.1sx.
hep-phCommun.Theor.Phys.(2024)·2 citations
08*
Energy flow in ultra-high energy cosmic ray interactions as a probe of thermalization: a potential solution to the muon puzzle
Ronald Scaria🇮🇳 · Suman Deb🇫🇷 · Captain R. Singh🇮🇳 · Raghunath Sahoo🇮🇳
Signatures of the formation of a strongly interacting thermalized matter of partons have been observed in nucleus-nucleus, proton-nucleus, and high-multiplicity proton-proton collisions at LHC energies. Strangeness enhancement in such ultra-relativistic heavy-ion collisions is considered to be a consequence of this thermalized phase, known as quark-gluon plasma (QGP). Simultaneously, proper modeling of hadronic energy fraction in interactions of ultra-high energy cosmic rays (UHECR) has been proposed as a solution for the muon puzzle, an unexpected excess of muons in air showers. These interactions have center-of-mass collision energies of the order of energies attained at the LHC or even higher, indicating that the possibility of a thermalized partonic state cannot be overlooked in UHECR-air interactions. This work investigates the hadronic energy fraction and strangeness enhancement to explore QGP-like phenomena in UHECR-air interactions using various high-energy hadronic models. A core-corona system with a thermalized core undergoing statistical hadronization is considered through the EPOS LHC model. In contrast, PYTHIA 8, QGSJET II-04, and SYBILL 2.3d consider string fragmentation without thermalization. We have found that EPOS LHC gives a better description of strangeness enhancement as compared to other models. We conclude that adequately treating all the relevant effects and further retuning the models is necessary to explain the observed effects.
hep-phastro-ph.HEhep-exhep-th+1PLB(2023)·5 citations
09*
Spontaneous Human Combustion rules out all standard candidates for Dark Matter
Frederic V. Hessman🇩🇪 · J. Craig Wheeler🇺🇸
We argue that the reported cases of Spontaneous Human Combustion (SHC) are most likely due to the impact of the human body with an extremely high energy particle like cosmic rays or Dark Matter. Normal and antimatter cosmic rays and classical weakly-interacting massive particles (WIMPs) with energies of GeV to ZeV can be easily ruled out due to their inability to dump enough energy into a small region of human tissue, leaving as the single remaining candidate massive Dark Matter particles. While primordial Black Holes would appear to be very good candidates for inducing the SHC phenomenon, we show that the estimated local Dark Matter density requires that the particles have masses of $\sim 10$ \,kg, clearly ruling out this candidate. All of the other classic DM candidates -- from scalar and pseudo-scalar spin 1/2 and spin 2 gauge singlets to nuclearitic strange quark ``bowling balls'' -- can be ruled out. Axions tailored to solve the CP-problem also cannot be invoked, no matter what mass is considered. The only particles left are massive mega-axions (MaMAs), for which there are an infinite number of possible string models.
hep-phastro-ph.COhep-th2 citations
10*
Utilizing maximum likelihood estimator for flow analysis
Chong Ye🇨🇳 · Wei-Liang Qian🇨🇳 · Rui-Hong Yue🇨🇳 · Yogiro Hama🇧🇷 · Takeshi Kodama🇧🇷
We explore the possibility of evaluating flow harmonics by employing the maximum likelihood estimator (MLE). For a given finite multiplicity, the MLE simultaneously furnishes estimations for all the parameters of the underlying distribution function while efficiently suppressing the variance of measures. Also, the method provides a means to assess a specific class of mixed harmonics, which is not straightforwardly feasible by the approaches primarily based on particle correlations. The results are analyzed using the Wald, likelihood ratio, and score tests of hypotheses. Besides, the resultant flow harmonics obtained using MLE are compared with those derived using particle correlations and event plane methods. The dependencies of extracted flow harmonics on the multiplicity of individual events and the total number of events are analyzed. It is shown that the proposed approach works efficiently to deal with the deficiency in detector acceptability. Moreover, we elaborate on a fictitious scenario where the event plane is not a well-defined quantity in the distribution function. For the latter case, the MLE is shown to largely perform better than the two-particle correlation estimator. In this regard, one concludes that the MLE furnishes a meaningful alternative to the existing approaches for flow analysis.
hep-phPRC(2023)·7 citations
11*
SN1987A cooling due to Plasmon-Plasmon scattering in the Randall-Sundrum Model
Manish Kumar Sharma🇮🇳 · Saumyen Kundu🇮🇳 · Prasanta Kumar Das🇮🇳
The light braneworld radion, stabilized via the Goldberger-Wise mechanism in the Randall-Sundrum model, can be produced copiously inside the supernova core due to plasmon-plasmon annihilations. The radion, thus produced, subsequently decays to a neutrino-antineutrino pair and takes away the energy released in the SN1987A explosion. Assuming that the supernovae cooling rate for any new physics channel(Raffelt's criterion) $ε ˙ (γ_{P} γ_{P} ⟶ ϕ ν_{τ} ν_{τ}) \leq 7.288 \times 1 0^{- 27} GeV$ , we find the lower bound on the radion vacuum expectation value $⟨ ϕ ⟩ \sim 3$ ~TeV for $m_{ϕ} = 30$ MeV corresponding to the deformation parameter $q = 1.17$ in the Tsallis statistics formalism. In the scenario with $q = 1$ , we find $⟨ ϕ ⟩ = 178$ GeV for $m_{ϕ} = 30$ MeV.
hep-phPhys.Dark Univ.(2023)·1 citation
12*
Excited $Ω_{c}$ baryons as 2S states
Marek Karliner🇮🇱 · Jonathan L. Rosner🇺🇸
The LHCb experiment has recently reported two excited $Ω_{c}$ resonances decaying to $Ξ_{c}^{+} K^{-}$ , with masses about 3185 and 3327 MeV. We discuss their assignment to $2 S_{1/2}$ and $2 S_{3/2}$ states, which can be compared with masses based on extrapolation from the observed 1S states. The agreement is not perfect, but weighs against an earlier alternative assignment.
hep-phPRD(2023)·18 citations
13*
Transverse momentum and multiplicity dependence of $Λ_{c}^{+} / D^{0}$ ratio in $pp$ collisions at $s = 13$ TeV
Jun Song🇨🇳 · Hai-hong Li🇨🇳 · Feng-lan Shao🇨🇳
We apply an equal-velocity quark combination model to study the $Λ_{c}^{+} / D^{0}$ ratio in the range $p_{T} ≲ 10$ GeV/c in $pp$ collisions at $s = 13$ TeV. We decompose the ratio into four parts which are related to quark numbers, light-flavor quark $p_{T}$ spectrum, charm quark $p_{T}$ spectrum, momentum correlation between light and charm quarks, respectively. Their influence on $Λ_{c}^{+} / D^{0}$ ratio are individually studied. The curvature property of light-flavor quark $p_{T}$ spectrum is found to be the main reason of the non-monotonic $p_{T}$ dependence of $Λ_{c}^{+} / D^{0}$ ratio exhibited in high multiplicity events. Moreover, the multiplicity dependence of $Λ_{c}^{+} / D^{0}$ ratio as the function of $p_{T}$ is mainly because of the multiplicity dependence of light-flavor quark $p_{T}$ spectrum. Using the light-flavor quark $p_{T}$ spectrum obtained from experimental data of light-flavor hadrons and charm quark $p_{T}$ spectrum obtained from FONLL and/or PYTHIA calculations, the $p_{T}$ dependence of experimental data of $Λ_{c}^{+} / D^{0}$ ratio in high multiplicity events and that in low multiplicity events in $pp$ collisions at $s = 13$ TeV are reasonably understood.
hep-phEPJC(2023)·3 citations
14*
Investigation of the strange pentaquark candidate $P_{ψ s}^{Λ} (4338)^{0}$ recently observed by LHCb
K. Azizi🇮🇷 · Y. Sarac🇹🇷 · H. Sundu🇹🇷
The recently observed strange pentaquark candidate, $P_{ψ s}^{Λ} (4338)^{0}$ , is investigated to provide information about its nature and substructure. To this end, its mass and width through the decay channels $P_{ψ s}^{Λ} (4338)^{0} \to J / ψ Λ$ and $P_{ψ s}^{Λ} (4338)^{0} \to η_{c} Λ$ are calculated by applying two- and three-point QCD sum rules, respectively. The state is considered as a $Ξ_{c} D ˉ$ meson-baryon molecular structure with spin-parity quantum numbers $J^{P} = \frac{1}{2}^{-}$ . The obtained mass, $m_{P_{ψ s}^{Λ} (4338)^{0}} = 4338 \pm 130 MeV$ , and width, $Γ_{P_{ψ s}^{Λ} (4338)^{0}} = 10.40 \pm 1.93 MeV$ , are consistent with the experimental data within the presented uncertainties. This allows us to assign a $Ξ_{c} D ˉ$ molecular structure of $J^{P} = \frac{1}{2}^{-}$ for the $P_{ψ s}^{Λ} (4338)^{0}$ state.
hep-phhep-exhep-latPRD(2023)·20 citations
15*
Dark Matter in a bi-metric universe
Carlos Maldonado🇨🇱 · Fernando Mendez🇨🇱
We study the possibility to describe dark matter in a model of the universe with two scale factors and a non-standard Poisson bracket structure characterized by the deformation parameter \kappa. The dark matter evolution is analyzed in the early stages of the universe, and its relic density is obtained via the Freeze-In and Freeze-Out mechanism. We show that by fixing ąppa} and the initial ratio of energy densities present in the different sectors of the universe, the space of thermal average annihilation cross-sections and dark matter masses compatible with the standard cosmology prior to Big Bang Nucleosynthesis (BBN), is enlarged. This feature of the model is compatible with non-standard cosmology.
hep-phInt.J.Mod.Phys.D(2023)·4 citations
16*
Decay dynamics of $N \to ℓ π$ and $N \to ℓ γ$
Svjetlana Fajfer🇸🇮 · Mitja Sadl🇸🇮
SuperKamiokande experiment tightly bounds the lifetimes of the baryon number violating proton decays. The decay widths for the nucleon to an antilepton and a photon are not so well bounded experimentally as $ℓ π$ modes. Using an effective Lagrangian approach, we relate the decay widths of $N \to ℓ γ$ to the decay widths of $N \to ℓ π$ . Our result points out factor $1 0^{3}$ suppression of the decay widths $Γ (p \to ℓ^{+} γ)$ and $Γ (n \to ν ˉ γ)$ compared to the decay widths $Γ (p \to ℓ^{+} π^{0})$ and $Γ (n \to ν ˉ π^{0})$ , respectively. This result is independent of the model of new physics. Then, we investigate the dynamics of $N \to ℓ π$ and $N \to ℓ γ$ amplitudes at the tree and loop level in which scalar leptoquarks are mediators of a new interaction. At the tree level, leptoquarks probe the physics beyond the Standard Model at a scale of $1 0^{16}$ GeV, while at the loop level, such decay can occur at a scale of $1 0^{7}$ GeV.
hep-phhep-exPRD(2023)·10 citations
17*
Freeze-in of WIMP dark matter
Xiao-Rui Wang🇨🇳 · Ke-Pan Xie🇨🇳
The nature of dark matter (DM) remains one of the most important unanswered questions in particle physics. Here, we propose a novel scenario for DM in which weakly interacting massive particles (WIMPs) can freeze-in due to a first-order phase transition (FOPT) in the early Universe. The FOPT dilutes the pre-existing DM density to zero and leads to a sudden change in DM mass, preventing WIMPs from re-equilibrating due to their large mass-to-temperature ratio. Following the FOPT, WIMPs are produced via a freeze-in process, even though their interactions are NOT feeble. We demonstrate this concept using a simplified model and then apply it to a realistic model with a delayed electroweak phase transition. Our work presents a promising new direction for the freeze-in mechanism, and also extends the category of WIMP DM.
hep-phastro-ph.COPRD(2023)·32 citations
18*
Sterile neutrino searches with reactor antineutrinos using coherent neutrino-nucleus scattering experiments
S. P. Behera · D. K. Mishra · P. K. Netrakanti · R. Sehgal · R. Dey · V. Jha
We present an analysis on the sensitivity to the active-sterile neutrino mixing with Germanium (Ge) and Silicon (Si) detectors in the context of the proposed coherent elastic neutrino-nucleus experiment in India. The study has been carried out with 3 (active) $+$ 1 (sterile) neutrino oscillation model. It is observed that the measurements that can be carried out with the Ge detector exhibit better sensitivity to the active-sterile neutrino mixing as compared to the Si detector. Both detectors are able to exclude most of the anomaly regions observed by the GALLIUM experiment. The Ge detector with mass 10 kg, can observe the active-sterile neutrino oscillation at 95 $%$ confidence level, provided that $sin^{2} 2 θ_{14} \geq 0.09$ at $Δ m_{41}^{2}$ = 1.0 eV $^{2}$ for an exposure of 1-yr. At higher values of $Δ m_{41}^{2}$ , a better sensitivity is obtained at a short baseline. It is also found that the threshold as well as resolution of the detectors play a crucial role on the measurements of active-sterile neutrino mixing parameters.
hep-phhep-exnucl-thPRD(2023)·6 citations
19*
Supermassive black holes triggered by QCD axion bubbles
Hai-Jun Li🇨🇳 · Ying-Quan Peng🇨🇳 · Wei Chao🇨🇳 · Yu-Feng Zhou🇨🇳
The supermassive black holes (SMBHs) are ubiquitous in the center of galaxies, although the origin of their massive seeds is still unknown. In this paper, we investigate the SMBHs formation from the QCD axion bubbles. In this case, the primordial black holes (PBHs) are considered as the seeds of SMBHs, which are generated from the QCD axion bubbles due to an explicit Peccei-Quinn (PQ) symmetry breaking after inflation. The QCD axion bubbles are formed when the QCD axion starts to oscillate during the QCD phase transition. We consider a general case in which the axion bubbles are formed with the bubble effective angle $θ_{eff} \in (0, π]$ , leading to the minimum PBH mass $\sim O (1 0^{4} - 1 0^{7}) M_{⊙}$ for the axion decay constant $f_{a} \sim O (1 0^{16}) GeV$ . The PBHs at this mass region may account for the seeds of SMBHs.
hep-phastro-ph.COastro-ph.HECommun.Theor.Phys.(2024)·9 citations
20*
Towards the precision measurement of CP violation in $B \to D^{*} μν$ decays at LHCb
Vlad Dedu🇫🇷 · Anton Poluektov🇫🇷
Measurement of $C P$ -violating observables in semileptonic decays is a sensitive null-test of the Standard Model: any $C P$ violation would be an unambiguous sign of New Physics effects. The model-independent technique to measure parity and $C P$ -odd observables in the $B \to D^{*} μν$ decays is proposed, which effectively cancels out parity-even terms in the decay density together with the associated theory uncertainty. The feasibility study is performed with pseudoexperiments, and the sensitivity at the LHCb experiment is estimated. Finally, the most significant systematic effects and the data-driven ways to control them are considered.
hep-phhep-exJHEP(2023)·1 citation
21*
Solar radio emissions and ultralight dark matter
Haipeng An🇨🇳 · Shuailiang Ge🇨🇳 · Jia Liu🇨🇳
Ultralight axions and dark photons are well-motivated dark matter candidates. Inside the plasma, once the mass of ultralight dark matter candidates equals the plasma frequency, they can resonantly convert into electromagnetic waves, due to the coupling between the ultralight dark matter particles and the standard model photons. The converted electromagnetic waves are monochromatic. In this article, we review the development of using radio detectors to search for ultralight dark matter conversions in the solar corona and solar wind plasma.
hep-phastro-ph.COastro-ph.HEastro-ph.SR+1Universe(2023)·16 citations
22*
Investigating the GmSUGRA in the MSSM through the long-lived bino NLSP at the HL-LHC
Wenxing Zhang🇨🇳 · Waqas Ahmed🇨🇳 · Imtiaz Khan🇨🇳 · Tianjun Li🇨🇳 · Shabbar Raza🇵🇰
The axino, the supersymmetric partner of axion, is a well-motivated warm/hot dark matter candidate, and provides a natural solution to the relic density problem for the bino-like neutralino if it is the lightest supersymmetric particle (LSP). With the Generalized Minimal Supergravity, we study such kind of the viable parameter space where the bino-like neutralino is the next-to-LSP (NLSP) and the axino is the LSP. In addition, we consider a scenario where the bino is a long-lived NLSP with the lifetime varying from $1 0^{- 6}$ s to $1 0^{- 4}$ s, and then propose a new signal searching scheme involving one displaced photon together with the large missing transverse momentum at the HL-LHC. The bino-like lightest neutralino lies under or around 100 GeV and is produced as a decay product of the right-handed sleptons.The relevant axion coupling $f_{a}$ can be probed up to $O (1 0^{9})$ GeV at 2 $σ$ level for the right-handed slepton mass under 300 GeV and the lightest neutralino mass under 100 GeV.
hep-phPRD(2024)·4 citations
23*
Invariant mass reconstruction of heavy gauge bosons decaying to $τ$ leptons using machine learning techniques
Vinaya Krishnan MB🇮🇳 · Aruna Kumar Nayak🇮🇳 · Asrith Krishna Radhakrishnan🇮🇳
Many analyses are performed by the LHC experiments to search for heavy gauge bosons, which appear in several new physics models. The invariant mass reconstruction of heavy gauge bosons is difficult when they decay to $τ$ leptons due to missing neutrinos in the final state. Machine learning techniques are widely utilized in experimental high-energy physics, in particular in analyzing the large amount of data produced at the LHC. In this paper, we study machine learning techniques such as supervised and unsupervised neural network algorithms to reconstruct the invariant mass of $Z^{'} \to τ τ$ and $W^{'} \to τ ν$ decays, which can improve the sensitivity of these searches.
hep-phhep-exEPJC(2024)·3 citations
24*
Clustering and visualization tools to study high dimensional parameter spaces: B anomalies example
Ursula Laa🇦🇹 · German Valencia🇦🇺
We describe the applications of clustering and visualization tools using the so-called neutral B anomalies as an example. Clustering permits parameter space partitioning into regions that can be separated with some given measurements. It provides a visualization of the collective dependence of all the observables on the parameters of the problem. These methods highlight the relative importance of different observables, and the effect of correlations, and help to understand tensions in global fits. The tools we describe also permit a visual inspection of high dimensional observable and parameter spaces through both linear projections and slicing.
↳ physics.data-anhep-exhep-phPoS(2023)·0 citations
25*
Gauge fixing and physical symmetries
Duifje Maria van Egmond🇫🇷 · Urko Reinosa🇫🇷
We analyze how gauge fixing, which is required by any practical continuum approach to gauge systems, can interfere with the physical symmetries of such systems. In principle, the gauge fixing procedure, which deals with the (unphysical) gauge symmetry, should not interfere with the other (physical) symmetries. In practice, however, there can be an interference which takes two different forms. First, depending on the considered gauge, it might not always be simple or possible to devise approximation schemes that preserve the physical symmetry constraints on (gauge-independent) observables. Second, even at an exact level of discussion, the (gauge-dependent) effective action for the gauge field, and thus the related vertex functions, may not reflect the physical symmetries of the problem. We illustrate these difficulties using a very general class of gauge fixings that contains the usual gauge fixings as particular cases. Using background field techniques, we then propose specific gauge choices that allow one to keep the physical symmetries explicit, both at the level of the observables and at the level of the effective action for the gauge field. Our analysis is based on the notion of invariance modulo gauge transformations. This is not only a convenient framework to discuss symmetries in the presence of unphysical degrees of freedom, but it also allows one to reinterpret certain well known phenomena in gauge theories without the need to invoke the conceptually annoying ``breaking of a gauge symmetry''.
↳ hep-thhep-phPRD(2023)·8 citations
26*
Reanalysis of the Systematic Uncertainties in Cosmic-Ray Antiproton Flux
Xing-Jian Lv🇨🇳 · Xiao-Jun Bi🇨🇳 · Kun Fang🇨🇳 · Peng-Fei Yin🇨🇳 · Meng-Jie Zhao🇨🇳
Recent studies on cosmic rays (CRs) have reported the possibility of an excess in the antiproton flux around $10 - 20$ GeV. However, the associated systematic uncertainties have impeded the interpretation of these findings. In this study, we conduct a global Bayesian analysis to constrain the propagation parameters and evaluate the CR antiproton spectrum, while comprehensively accounting for uncertainties associated with interstellar CR propagation, production cross sections for antiprotons and other secondaries, and the charge and energy dependent effects of solar modulation. We establish that the most recent AMS-02 $p ˉ$ spectrum is in agreement with a pure secondary origin. Based on this, we establish upper limits on dark matter (DM) annihilation. We also determine that the AMS-02 data favors the empirical hadronic interaction models over phenomenological ones. Finally, we find that the latest AMS-02 antiproton data from 2011 to 2018 disfavors the antiproton excess at $O$ (10) GeV and the corresponding DM interpretation that can simultaneously account for the Galactic Center excess in the gamma-ray observation.
↳ astro-ph.HEhep-phPRD(2024)·8 citations
27*
One-loop matching of $C P$ -odd four-quark operators to the gradient-flow scheme
Jona Bühler🇨🇭 · Peter Stoffer🇨🇭
The translation of experimental limits on the neutron electric dipole moment into constraints on heavy $C P$ -violating physics beyond the Standard Model requires knowledge about non-perturbative matrix elements of effective operators, which ideally should be computed in lattice QCD. However, this necessitates a matching calculation as an interface to the effective field theory framework, which is based on dimensional regularization and renormalization by minimal subtraction. We calculate the one-loop matching between the gradient-flow and minimal-subtraction schemes for the $C P$ -violating four-quark operators contributing to the neutron electric dipole moment. The gradient flow is a modern regularization-independent scheme amenable to lattice computations that promises, e.g., better control over power divergences than traditional momentum-subtraction schemes. Our results extend previous work on dimension-five operators and provide a necessary ingredient for future lattice-QCD computations of the contribution of four-quark operators to the neutron electric dipole moment.
↳ hep-lathep-exhep-phnucl-thJHEP(2023)·15 citations
28*
Relativistic second-order spin hydrodynamics: an entropy-current analysis
Rajesh Biswas🇵🇱 · Asaad Daher🇵🇱 · Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱
We present a new derivation of Israel-Stewart-like relativistic second-order dissipative spin hydrodynamic equations using the entropy current approach. In our analysis, we consider a general energy-momentum tensor with symmetric and anti-symmetric parts. Moreover, the spin tensor, which is not separately conserved, has a simple phenomenological form that is antisymmetric only in the last two indices. Apart from the evolution equations for energy density, fluid flow, and spin density, we also find relaxation-type dynamical equations for various dissipative currents. The latter are consistently derived within the second-order theory as gradient corrections to the energy-momentum and spin tensors. We argue that this approach correctly reproduces the corresponding Navier-Stokes limit of spin hydrodynamic equations. Throughout our analysis, the spin chemical potential is considered a $O (\partial)$ quantity in the hydrodynamic gradient expansion and reduces to thermal vorticity in the global equilibrium. New coefficients appearing in the generalized spin hydrodynamic equations are undetermined and can only be evaluated within a proper underlying microscopic theory of a given system.
↳ nucl-thhep-phPRD(2023)·70 citations
29*
BRST invariant formulation of the Bell-CHSH inequality in gauge field theories
David Dudal🇧🇪 · Philipe De Fabritiis🇧🇷 · Marcelo S. Guimaraes🇧🇷 · Giovani Peruzzo🇧🇷 · Silvio P. Sorella🇧🇷
A study of the Bell-CHSH inequality in gauge field theories is presented. By using the Kugo-Ojima analysis of the BRST charge cohomology in Fock space, the Bell-CHSH inequality is formulated in a manifestly BRST invariant way. The examples of the free four-dimensional Maxwell theory and the Abelian Higgs model are scrutinized. The inequality is probed by using BRST invariant squeezed states, allowing for large Bell-CHSH inequality violations, close to Tsirelson's bound. An illustrative comparison with the entangled state of two $1/2$ spin particles in Quantum Mechanics is provided.
↳ hep-thhep-phquant-phSciPost Phys.(2023)·8 citations
30*
Investigating the gamma-ray burst from decaying MeV-scale axion-like particles produced in supernova explosions
Eike Müller🇸🇪 · Francesca Calore🇫🇷 · Pierluca Carenza🇸🇪 · Christopher Eckner🇫🇷 · M.C. David Marsh🇸🇪
We investigate the characteristics of the gamma-ray signal following the decay of MeV-scale Axion-Like Particles (ALPs) coupled to photons which are produced in a Supernova (SN) explosion. This analysis is the first to include the production of heavier ALPs through the photon coalescence process, enlarging the mass range of ALPs that could be observed in this way and giving a stronger bound from the observation of SN 1987A. Furthermore, we present a new analytical method for calculating the predicted gamma-ray signal from ALP decays. With this method we can rigorously prove the validity of an approximation that has been used in some of the previous literature, which we show here to be valid only if all gamma rays arrive under extremely small observation angles (i.e. very close to the line of sight to the SN). However, it also shows where the approximation is not valid, and offers an efficient alternative to calculate the ALP-induced gamma-ray flux in a general setting when the observation angles are not guaranteed to be small. We also estimate the sensitivity of the Fermi Large Area Telescope (Fermi-LAT) to this gamma-ray signal from a future nearby SN and show that in the case of a non-observation the current bounds on the ALP-photon coupling $g_{aγ}$ are strengthened by about an order of magnitude. In the case of an observation, we show that it may be possible to reconstruct the product $g_{aγ}^{2} m_{a}$ , with $m_{a}$ the mass of the ALP.
↳ astro-ph.HEhep-phJCAP(2023)·69 citations
31*
$S p (2 N)$ Lattice Gauge Theories and Extensions of the Standard Model of Particle Physics
Ed Bennett🇬🇧 · Jack Holligan🇺🇸 · Deog Ki Hong🇰🇷 · Ho Hsiao🇹🇼 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Michele Mesiti🇬🇧 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧
We review the current status of the long-term programme of numerical investigation of $S p (2 N)$ gauge theories with and without fermionic matter content. We start by introducing the phenomenological as well as theoretical motivations for this research programme, which are related to composite Higgs models, models of partial top compositeness, dark matter models, and in general to the physics of strongly coupled theories and their approach to the large-N limit. We summarise the results of lattice studies conducted so far in the $S p (2 N)$ Yang-Mills theories, measuring the string tension, the mass spectrum of glueballs and the topological susceptibility, and discuss their large-N extrapolation. We then focus our discussion on $S p (4)$ , and summarise numerical measurements of mass and decay constant of mesons in the theories with fermion matter in either the fundamental or the antisymmetric representation, first in the quenched approximation, and then with dynamical fermions. We finally discuss the case of dynamical fermions in mixed representations, and exotic composite fermion states such as the chimera baryons. We conclude by sketching the future stages of the programme. And we describe our approach to open access.
↳ hep-lathep-phhep-thUniverse(2023)·46 citations
32*
On the primordial black hole formation in hybrid inflation
Yuichiro Tada🇯🇵 · Masaki Yamada🇯🇵
We revisit the scenario of primordial black hole (PBH) formation from large curvature perturbations generated during the waterfall phase transition in hybrid inflation models. In a minimal setup considered in the literature, the mass and abundance of PBHs are correlated and astrophysical size PBHs tend to be overproduced. This is because a longer length scale for curvature perturbations (or a larger PBH mass) requires a longer waterfall regime with a flatter potential, which results in overproduction of curvature perturbations. However, in this paper, we discuss that the higher-dimensional terms for the inflaton potential affect the dynamics during the waterfall phase transition and show that astrophysical size PHBs of order $1 0^{17 - 23} g$ (which can explain the whole dark matter) can form in some parameter space consistently with any existing constraints. The scenario can be tested by observing the induced gravitational waves from scalar perturbations by future gravitational wave experiments, such as LISA.
↳ astro-ph.COgr-qchep-phPRD(2023)·25 citations
33*
Constraints on massive gravity from dipolar mode excitations
Vitor Cardoso🇩🇰 · Francisco Duque🇵🇹 · Andrea Maselli🇮🇹 · David Pereñiguez🇩🇰
We study extreme-mass-ratio systems in theories admitting the Schwarzschild solution and propagating a massive graviton. We show that, in addition to small corrections to the quadrupolar and higher-order modes, a dipolar mode is excited in these theories and we quantify its excitation. While LIGO-Virgo-KAGRA observations are not expected to impose meaningful constraints in the dipolar sector, future observations by the Einstein Telescope or by LISA, together with bounds from dispersion relations, can rule out theories of massive gravity admitting vacuum General Relativistic backgrounds. For the bound to be circumvented, one needs to move away from Ricci-flat solutions, and enter a territory where constraints based on wave propagation and dispersion relations are not reliable.
↳ gr-qcastro-ph.HEhep-phhep-thPRD(2023)·9 citations
34*
A novel prediction for secondary positrons and electrons in the Galaxy
Mattia Di Mauro🇮🇹 · Fiorenza Donato🇮🇹 · Michael Korsmeier🇸🇪 · Silvia Manconi🇩🇪 · Luca Orusa🇮🇹
The Galactic flux of cosmic-ray (CR) positrons in the GeV to TeV energy range is very likely due to different Galactic components. One of these is the inelastic scattering of CR nuclei with the atoms of the interstellar medium. The precise amount of this component determines the eventual contribution from other sources. We present here a new estimation of the secondary CR positron flux by incorporating the latest results for the production cross sections of $e^{\pm}$ from hadronic scatterings calibrated on collider data. All the reactions for CR nuclei up to silicon scattering on both hydrogen and helium are included. The propagation models are derived consistently by fits on primary and secondary CR nuclei data. Models with a small halo size ( $L \leq 2$ kpc) are disfavored by the nuclei data although the current uncertainties on the beryllium nuclear cross sections may impact this result. The resulting positron flux shows a strong dependence on the Galactic halo size, increasing up to factor 1.5 moving $L$ from 8 to 2 kpc. Within the most reliable propagation models, the positron flux matches the data for energies below 1 GeV. We verify that secondary positrons contribute less than $70%$ of the data above a few GeV, corroborating that an excess of positrons is already present at very low energies. At larger energies, our predictions are below the data with the discrepancy becoming more and more pronounced. Our results are provided together with uncertainties due to propagation and hadronic cross sections. The former uncertainties are below 5\% at fixed $L$ , while the latter are about 7\% almost independently of the propagation scheme. In addition to the predictions of positrons, we provide new predictions also for the secondary CR electron flux.
↳ astro-ph.HEhep-phPRD(2023)·24 citations
35*
Novel transition dynamics of topological solitons
Kentaro Nishimura🇯🇵 · Noriyuki Sogabe🇺🇸
Continuous phase transitions can be classified into ones characterized by local-order parameters and others that need additional topological constraints. The critical dynamics near the former transitions have been extensively studied, but the latter is less understood. We fill this gap in knowledge by studying the transition dynamics to a parity-breaking topological ground state called the chiral soliton lattice in quantum chromodynamics at finite temperature, baryon chemical potential, and external magnetic field. We find a slowing down of the soliton's translational motion as the critical magnetic field approaches while the local dissipation rate remains finite. Therefore, the characteristic time it takes to converge to the stationary state associated with a finite topological number strongly depends on the initial configuration: whether it forms a solitonic structure or not.
↳ hep-thcond-mat.mtrl-scihep-phnucl-thPRD(2024)·2 citations
36*
Black hole superradiant instability for massive spin-2 fields
Oscar J. C. Dias🇬🇧 · Giuseppe Lingetti🇮🇹 · Paolo Pani🇮🇹 · Jorge E. Santos🇬🇧
Due to coherent superradiant amplification, massive bosonic fields can trigger an instability in spinning black holes, tapping their energy and angular momentum and forming macroscopic Bose-Einstein condensates around them. This phenomenon produces gaps in the mass-spin distribution of astrophysical black holes, a continuous gravitational-wave signal emitted by the condensate, and several environmental effects relevant for gravitational-wave astronomy and radio images of black holes. While the spectrum of superradiantly unstable mode is known in great detail for massive scalar (spin-0) and vector (spin-1) perturbations, so far only approximated results were derived for the case of massive tensor (spin-2) fields, due to the nonseparability of the field equations. Here, solving a system of ten elliptic partial differential equations, we close this program and compute the spectrum of the most unstable modes of a massive spin-2 field for generic black-hole spin and boson mass, beyond the hydrogenic approximation and including the unique dipole mode that dominates the instability in the spin-2 case. We find that the instability timescale for this mode is orders of magnitude shorter than for any other superradiant mode, yielding much stronger constraints on massive spin-2 fields. These results pave the way for phenomenological studies aimed at constraining beyond Standard Model scenarios, ultralight dark matter candidates, and extensions to General Relativity using gravitational-wave and electromagnetic observations, and have implications for the phase diagram of vacuum solutions of higher-dimensional gravity.
↳ gr-qcastro-ph.HEhep-phhep-thPRD(2023)·45 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.