Measurement of the mass difference and relative production rate of the and baryons

Journal of Instrumentation

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using ???????? collision data at

arXiv preprint arXiv:2404.19510

The four decays, , are observed for the first time using proton-proton collision data collected with the LHCb detector at a centre-of-mass energy of , corresponding to an integrated luminosity of . By considering the decay as reference channel, the following branching fraction ratios are measured to be, $$\frac{\cal{B} (\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{++} \rm{D}^{-} {K}^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Lambda_c^{+} \rm \overline{D}^0 {K}^{-})} = {0.282}\pm{0.016}\pm{0.016}\pm{0.005}, \frac{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{*++} \rm {D}^{-} {K}^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} \rm {D}^{-} {K}^{-})} = {0.460}\pm{0.052}\pm{0.028}, \frac{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{++} \rm {D}^{*-} {K}^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} \rm {D}^{-} {K}^{-})} = {2.261}\pm{0.202}\pm{0.129}\pm{0.046}, \frac{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_{c}^{*++} \rm D^{*-} K^{-})}{\cal{B}(\Lambda_{b}^{0} \rightarrow \Sigma_c^{++} \rm D^{-} K^{-})} = {0.896}\pm{0.137}\pm{0.066}\pm{0.018},$$ where the first uncertainties are statistical, the second are systematic, and the third are due to uncertainties in the branching fractions of intermediate particle decays. These initial observations mark the beginning of pentaquark searches in these modes, with more data set to become available following the LHCb upgrade.

Journal of High Energy Physics

A measurement of CP-violating observables in B±→ D* K±and B±→ D* π±decays is made where the photon or neutral pion from the D*→ Dγ or D*→ Dπ 0 decay is not reconstructed. The D meson is reconstructed in the self-conjugate decay modes, D→ π+ π− or D→ K+ K−. The distribution of signal yields in the D decay phase space is analysed in a model-independent way. The measurement uses a data sample collected in proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of approximately 9 fb− 1. The B±→ D* K±and B±→ D* π±CP-violating observables are interpreted in terms of hadronic parameters and the CKM angle γ, resulting in a measurement of γ=(). The total uncertainty includes the statistical and systematic uncertainties, and the uncertainty due to external strong-phase inputs.

Physical Review Letters

A measurement of time-dependent CP violation in the decays of B 0 and B 0 mesons to the final states J/ψ (→ μ+ μ−) K S 0, ψ (2S)(→ μ+ μ−) K S 0 and J/ψ (→ e+ e−) K S 0 with K S 0→ π+ π− is presented. The data correspond to an integrated luminosity of 6 fb− 1 collected at a center-of-mass energy of√ s= 13 TeV with the LHCb detector. The CP-violation parameters are measured to be S ψK S 0= 0.717±0.013 (stat)±0.008 (syst) and C ψK S 0= 0.008±0.012 (stat)±0.003 (syst). This measurement of S ψK S 0 represents the most precise single measurement of the CKM angle β to date and is more precise than the current world average. In addition, measurements of the CP-violation parameters of the individual channels are reported and a combination with the LHCb Run 1 measurements is performed.

Journal of Instrumentation

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using ???????? collision data at

Physical review letters

The decay-time-dependent C P asymmetry in B s 0→ J/ψ (→ μ+ μ−) K+ K− decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 6 fb− 1, collected with the LHCb detector at a center-of-mass energy of 13 TeV. Using a sample of approximately 349 000 B s 0 signal decays with an invariant K+ K− mass in the vicinity of the ϕ (1020) resonance, the C P-violating phase ϕ s is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B s 0− Bs 0 system, Δ Γ s, and the difference of the average B s 0 and B 0 meson decay widths, Γ s− Γ d. The values obtained are ϕ s=− 0.039±0.022±0.006 rad, Δ Γ s= 0.0845±0.0044±0.0024 ps− 1, and Γ s− Γ d=− 0.05 6− 0.0015+ 0.0013±0.0014 ps− 1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements to date and are consistent with …

arXiv preprint arXiv:1612.08110

A search for the charmless decay is performed using collision data collected by the LHCb experiment at centre-of-mass energies of and TeV, corresponding to an integrated luminosity of 3 fb. No signal is observed and upper limits on the branching fraction are set to at and at confidence level.

arXiv preprint arXiv:2312.03130

DUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolution required to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise. In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D. Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are …

JOURNAL OF HIGH ENERGY PHYSICS

Null, N., Aaij, R., Abdelmotteleb, A., Abellan Beteta, C., Abudinén, F., Ackernley, T., et al.(2024). Study of Bc⁺→ χc π⁺ decays. JOURNAL OF HIGH ENERGY PHYSICS, 2024 (2)[10.1007/jhep02 (2024) 173].

Physical review letters

The decay-time-dependent C P asymmetry in B s 0→ J/ψ (→ μ+ μ−) K+ K− decays is measured using proton-proton collision data, corresponding to an integrated luminosity of 6 fb− 1, collected with the LHCb detector at a center-of-mass energy of 13 TeV. Using a sample of approximately 349 000 B s 0 signal decays with an invariant K+ K− mass in the vicinity of the ϕ (1020) resonance, the C P-violating phase ϕ s is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the B s 0− Bs 0 system, Δ Γ s, and the difference of the average B s 0 and B 0 meson decay widths, Γ s− Γ d. The values obtained are ϕ s=− 0.039±0.022±0.006 rad, Δ Γ s= 0.0845±0.0044±0.0024 ps− 1, and Γ s− Γ d=− 0.05 6− 0.0015+ 0.0013±0.0014 ps− 1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements to date and are consistent with …

arXiv preprint arXiv:2401.07564

In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.

Journal of High Energy Physics

A measurement of CP-violating observables in B±→ D* K±and B±→ D* π±decays is made where the photon or neutral pion from the D*→ Dγ or D*→ Dπ 0 decay is not reconstructed. The D meson is reconstructed in the self-conjugate decay modes, D→ π+ π− or D→ K+ K−. The distribution of signal yields in the D decay phase space is analysed in a model-independent way. The measurement uses a data sample collected in proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of approximately 9 fb− 1. The B±→ D* K±and B±→ D* π±CP-violating observables are interpreted in terms of hadronic parameters and the CKM angle γ, resulting in a measurement of γ=(). The total uncertainty includes the statistical and systematic uncertainties, and the uncertainty due to external strong-phase inputs.

arXiv preprint arXiv:2402.01568

Doping of liquid argon TPCs (LArTPCs) with a small concentration of xenon is a technique for light-shifting and facilitates the detection of the liquid argon scintillation light. In this paper, we present the results of the first doping test ever performed in a kiloton-scale LArTPC. From February to May 2020, we carried out this special run in the single-phase DUNE Far Detector prototype (ProtoDUNE-SP) at CERN, featuring 770 t of total liquid argon mass with 410 t of fiducial mass. The goal of the run was to measure the light and charge response of the detector to the addition of xenon, up to a concentration of 18.8 ppm. The main purpose was to test the possibility for reduction of non-uniformities in light collection, caused by deployment of photon detectors only within the anode planes. Light collection was analysed as a function of the xenon concentration, by using the pre-existing photon detection system (PDS) of ProtoDUNE-SP and an additional smaller set-up installed specifically for this run. In this paper we first summarize our current understanding of the argon-xenon energy transfer process and the impact of the presence of nitrogen in argon with and without xenon dopant. We then describe the key elements of ProtoDUNE-SP and the injection method deployed. Two dedicated photon detectors were able to collect the light produced by xenon and the total light. The ratio of these components was measured to be about 0.65 as 18.8 ppm of xenon were injected. We performed studies of the collection efficiency as a function of the distance between tracks and light detectors, demonstrating enhanced uniformity of response for the anode-mounted PDS …

arXiv preprint arXiv:2402.01336

Measurements of the branching fraction ratio with and decays, denoted and , are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4 of collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the and decay modes. The combination of the results yields The result is compatible with previous measurements of the branching fractions and predictions based on the Standard Model.

Physical review letters

A measurement of time-dependent C P violation in the decays of B 0 and B 0 mesons to the final states J/ψ (→ μ+ μ−) K S 0, ψ (2 S)(→ μ+ μ−) K S 0 and J/ψ (→ e+ e−) K S 0 with K S 0→ π+ π− is presented. The data correspond to an integrated luminosity of 6 fb− 1 collected at a center-of-mass energy of s= 13 TeV with the LHCb detector. The C P-violation parameters are measured to be S ψ K S 0= 0.717±0.013 (stat)±0.008 (syst) and C ψ K S 0= 0.008±0.012 (stat)±0.003 (syst). This measurement of S ψ K S 0 represents the most precise single measurement of the CKM angle β to date and is more precise than the current world average. In addition, measurements of the C P-violation parameters of the individual channels are reported and a combination with the LHCb Run 1 measurements is performed.

arXiv preprint arXiv:2402.05523

The first observation of the decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9fb, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the channel is measured to be $$ \frac{ {\cal{B}}( B_c^+ \to J/\psi \pi^+\pi^0 ) } { {\cal{B}}( B_c^+ \to J/\psi \pi^+ ) } = 2.80 \pm 0.15 \pm 0.11 \pm 0.16 \,, $$ where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for and decays, which are used to determine the detection efficiency. The mass spectrum is found to be consistent with the dominance of an intermediate contribution in accordance with a model based on QCD factorisation.

arXiv preprint arXiv:2402.14975

The LHCb collaboration measures production of the exotic hadron (3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state (2) suggests that the exotic (3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify (3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron.

The first observation of the B+ c→ J/ψπ+ π0 decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9 fb− 1, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13TeV. The ratio of its branching fraction relative to the B+ c→ J/ψπ+ channel is measured to be

arXiv preprint arXiv:2402.01336

Measurements of the branching fraction ratio with and decays, denoted and , are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4 of collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the and decay modes. The combination of the results yields The result is compatible with previous measurements of the branching fractions and predictions based on the Standard Model.

arXiv preprint arXiv:2401.11342

The production of mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb. The prompt and nonprompt production cross-sections and the ratio of the to cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt is observed to be more suppressed compared to collisions than the prompt production, while the nonprompt productions have similar suppression factors.

Physical Review D

The precision with which hadronic vacuum polarization (HVP) is obtained determines how accurately important observables, such as the muon anomalous magnetic moment a μ or the low-energy running of the electromagnetic coupling α, are predicted. The two most precise approaches for determining HVP are dispersive relations combined with e+ e−→ hadrons cross section data and lattice QCD. However, the results obtained in these two approaches display significant tensions, whose origins are not understood. Here we present a framework that sheds light on this issue and—if the two approaches can be reconciled—allows them to be combined. Via this framework, we test the hypothesis that the tensions can be explained by modifying the R-ratio in different intervals of center-of-mass energy s. As ingredients, we consider observables that have been precisely determined in both approaches. These are the …

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

In this work we analyze the motion of charged particles in the background of the Kiselev geometry, which is considered here as an exact solution in the context of power-Maxwell electrodynamics. As it is well known, one can use either an electric ansatz or a magnetic one for the nonlinear electromagnetic field. We study the motion of an electrically charged particle for an electrically charged black hole and also for a magnetically charged black hole. In the second case the motion is restricted to Poincaré cones of various angles, as expected.

Physical Review D

Ultracold atomic gases can undergo phase transitions that mimic relativistic vacuum decay, allowing us to empirically test early Universe physics in tabletop experiments. We investigate the physics of these analog systems, going beyond previous analyses of the classical equations of motion to study quantum fluctuations in the cold-atom false vacuum. We show that the fluctuation spectrum of this vacuum state agrees with the usual relativistic result in the regime where the classical analogy holds, providing further evidence for the suitability of these systems for studying vacuum decay. Using a suite of semiclassical lattice simulations, we simulate bubble nucleation from this analog vacuum state in a 1D homonuclear potassium-41 mixture, finding qualitative agreement with instanton predictions. We identify realistic parameters for this system that will allow us to study vacuum decay with current experimental …

Physical Review D

The evolution of linear initial conditions present in the early Universe into extended halos of dark matter at late times can be computed using cosmological simulations. However, a theoretical understanding of this complex process remains elusive; in particular, the role of anisotropic information in the initial conditions in establishing the final mass of dark matter halos remains a long-standing puzzle. Here, we build a deep learning framework to investigate this question. We train a three-dimensional convolutional neural network to predict the mass of dark matter halos from the initial conditions, and quantify in full generality the amounts of information in the isotropic and anisotropic aspects of the initial density field about final halo masses. We find that anisotropies add a small, albeit statistically significant amount of information over that contained within spherical averages of the density field about final halo mass …

Physical Review D

We investigate the hypothetical X17 boson on neutron stars and quark stars (QSs) using various hadronic equation of states (EoSs) with phenomenological or microscopic origin. Our aim is to set realistic constraints on its coupling constant and the mass scaling, with respect to causality and various possible upper mass limits and the dimensionless tidal deformability Λ 1.4. In particular, we pay special attention to two main phenomenological parameters of the X17, one is related to the coupling constant g that it has with hadrons or quarks and the other with the in-medium effects through regulator C. Both are very crucial concerning the contribution on the total energy density and pressure. In the case of considering the X17 as a carrier of nuclear force in relativistic mean field theory, an admixture into the vector boson segment was constrained by 20% and 30%. In our investigation, we came to the general conclusion …

Physical Review D

The recent analysis on the central compact object in the HESS J1731-347 remnant suggests interestingly small values for its mass and radius. Such an observation favors soft nuclear models that may be challenged by the observation of massive compact stars. In contrast, the recent PREX-II experiment, concerning the neutron skin thickness of Pb 208, points toward stiff equations of state that favor larger compact star radii. In the present study, we aim to explore the compatibility between stiff hadronic equations of state (favored by PREX-II) and the HESS J1731-347 remnant in the context of hybrid stars. For the construction of hybrid equations of state we use three widely employed Skyrme models combined with the well-known vector MIT bag model. Furthermore we consider two different scenarios concerning the energy density of the bag. In the first case, that of a constant bag parameter, we find that the resulting …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Physical Review D

We study the compact binary dynamics in the post-Newtonian approach implemented to the Einstein-Hilbert action adding the cosmological constant Λ at first post-Newtonian (1PN) order. We consider very small values of Λ finding that it plays the role of a PN factor to derive the Lagrangian of a compact two-body system at the center of mass frame at 1PN. Furthermore, the phase function ϕ (t) is obtained from the balance equation, and the two polarizations h+ and h× are also calculated. We observe changes due to Λ only at very low frequencies, and we notice that it plays the role of “stretch” the spacetime such that both amplitudes become smaller. However, given its nearly negligible value, Λ has no relevance at higher frequencies whatsoever.

Physical Review D

The nuclear reaction network within the interior of the Sun is an efficient MeV physics factory and can produce long-lived particles generic to dark sector models. In this work we consider the sensitivity of satellite instruments, primarily the RHESSI spectrometer, that observe the quiet Sun in the MeV regime where backgrounds are low. We find that quiet Sun observations offer a powerful and complementary probe in regions of parameter space, where the long-lived particle decay length is longer than the radius of the Sun and shorter than the distance between the Sun and Earth. We comment on connections to recent model-building work on heavy neutral leptons coupled to neutrinos and high-quality axions from mirror symmetries.

Physical Review D

Within the framework of relative and absolute quantum field theories (QFTs), we present a general formalism for understanding polarizations of the intermediate defect group and constructing noninvertible duality defects in theories in 2 k spacetime dimensions with self-dual gauge fields. We introduce the polarization pair, which fully specifies absolute QFTs as far as their (k− 1)-form defect groups are concerned, including their (k− 1)-form symmetries, global structures (including discrete θ-angle), and local counterterms. Using the associated symmetry topological field theory (TFT), we show that the polarization pair is capable of succinctly describing topological manipulations, eg, gauging (k− 1)-form global symmetries and stacking counterterms, of absolute QFTs. Furthermore, automorphisms of the (k− 1)-form charge lattice naturally act on polarization pairs via their action on the defect group; they can be viewed as …

Physical Review D

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c+ baryons, z∥ ch, in hadronic collisions. The results are obtained in proton-proton (p p) collisions at s= 13 TeV at the LHC, with Λ c+ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3≤ p T Λ c+< 15 GeV/c and 7≤ p T jet ch< 15 GeV/c, respectively. The z∥ ch distribution is compared to a measurement of D 0-tagged charged jets in p p collisions as well as to pythia 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Physical Review D

The second Gravitational-Wave Transient Catalog, GWTC-2, reported on 39 compact binary coalescences observed by the Advanced LIGO and Advanced Virgo detectors between 1 April 2019 15∶ 00 UTC and 1 October 2019 15∶ 00 UTC. Here, we present GWTC-2.1, which reports on a deeper list of candidate events observed over the same period. We analyze the final version of the strain data over this period with improved calibration and better subtraction of excess noise, which has been publicly released. We employ three matched-filter search pipelines for candidate identification, and estimate the probability of astrophysical origin for each candidate event. While GWTC-2 used a false alarm rate threshold of 2 per year, we include in GWTC-2.1, 1201 candidates that pass a false alarm rate threshold of 2 per day. We calculate the source properties of a subset of 44 high-significance candidates that have a …

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c+ baryons, z∥ ch, in hadronic collisions. The results are obtained in proton-proton (p p) collisions at s= 13 TeV at the LHC, with Λ c+ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3≤ p T Λ c+< 15 GeV/c and 7≤ p T jet ch< 15 GeV/c, respectively. The z∥ ch distribution is compared to a measurement of D 0-tagged charged jets in p p collisions as well as to pythia 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as …

Physical Review D

A search for quantum black holes in electron+ jet and muon+ jet invariant mass spectra is performed with 140 fb− 1 of data collected by the ATLAS detector in proton-proton collisions at s= 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton+ jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Physical Review D

We use data from the Atacama Cosmology Telescope (ACT) DR4 to search for the presence of neutrino self-interaction in the cosmic microwave background. Consistent with prior works, the posterior distributions we find are bimodal, with one mode consistent with Λ CDM and one where neutrinos strongly self-interact. By combining ACT data with large-scale information from WMAP, we find that a delayed onset of neutrino free streaming caused by significantly strong neutrino self-interaction is compatible with these data at the 2− 3 σ level. As seen in the past, the preference shifts to Λ CDM with the inclusion of Planck data. We determine that the preference for strong neutrino self-interaction is largely driven by angular scales corresponding to 700≲ ℓ≲ 1000 in the ACT E-mode polarization data. This region is expected to be key to discriminate between neutrino self-interacting modes and will soon be probed with …

Physical Review D

We determine the fine-tuning of the Yukawa couplings of supersymmetric QCD, discretized on a lattice. We use perturbation theory at one-loop level. The modified minimal subtraction scheme (MS) is employed; by its definition, this scheme requires perturbative calculations, in the continuum and/or on the lattice. On the lattice, we utilize the Wilson formulation for gluon, quark, and gluino fields; for squark fields we use naive discretization. The sheer difficulties of this study lie in the fact that different components of squark fields mix among themselves at the quantum level and the action’s symmetries, such as parity and charge conjugation, allow an additional Yukawa coupling. Consequently, for an appropriate fine-tuning of the Yukawa terms, these mixings must be taken into account in the renormalization conditions. All Green’s functions and renormalization factors are analytic expressions depending on the number of …