MyMedR

Displaying publications 1 - 20 of 229 in total

Abstract:

Sort:

Using game controller as position tracking sensor for 3D freehand ultrasound imaging

Chan VS, Mohamed F, Yusoff YA, Dewi DEO, Anuar A, Shamsudin MA, et al.

Med Biol Eng Comput, 2020 May;58(5):889-902.
PMID: 31599379 DOI: 10.1007/s11517-019-02044-4

Position tracking has been widely used in medical applications, especially in 3D ultrasound imaging, where it has transformed the 2D slice limitation into 3D volume with bigger clinical impacts. As a game controller can also produce position tracking information, it has the potential to act as a low-cost and portable position tracker for ultrasound probes. This paper aims to investigate the feasibility of a game controller to perform as a position tracker and to design its implementation in 3D ultrasound imaging. The study consists of data acquisition and 3D ultrasound reconstruction for visualization. The data acquisition is accomplished by capturing the 2D ultrasound frame and its relative positional and orientation data by using an ultrasound probe and game controller respectively. These data are further reconstructed to produce 3D ultrasound volume for visualization. Our experiments include game controller position tracker testing and 3D ultrasound reconstruction on baby phantom. The results have confirmed that the game controller performance was closely aligned with that of in a robot arm. Also, the 3D ultrasound reconstruction implementation has revealed promising outcomes. With these features, the function of the currently available ultrasound probes can be prospectively improved using a game controller position tracker effectively. Graphical Abstract.
Use of antifilarial IgG4-ELISA to detect Brugia malayi infection in an endemic area of Malaysia

Rahmah N, Anuar AK, Ariff RH, Zurainee MN, A'shikin AN, Fadzillah A, et al.

Trop Med Int Health, 1998 Mar;3(3):184-8.
PMID: 9593356

OBJECTIVE: To evaluate the usefulness of antifilarial IgG4 antibody assay in detecting B. malayi infection in a filaria endemic area in Malaysia.
METHODS: A sandwich ELISA using B. malayi soluble antigen was employed to detect antifilarial IgG4 antibodies in serum samples of 330 individuals who comprised 88 healthy individuals from nonendemic areas, 15 B. malayi microfilaraemic cases, 22 individuals with soil-transmitted helminthiases, 9 elephantiasis cases and 196 residents from a B. malayi-endemic area. An O.D. value of > 0.420 at serum dilution of 1:400 was used as the cut-off point. This cut-off point was obtained by taking the mean optical density (0.252 + 4 S.E.) of 36 negative sera which had O.D. values greater than 0.1 at serum dilution of 1:400.
RESULTS: All 15 microfilaraemic persons were positive for antifilarial IgG4 antibody. Non-endemic normals, soil-transmitted helminth infected persons and chronic elephantiasis cases were negative for antifilarial IgG4 antibody. Of the 196 individuals from the filaria endemic area, 37 (18.8%) demonstrated presence of antifilarial IgG4 antibodies; and only eight individuals (4.1%) were positive for microfilariae. All eight microfilaraemic individuals were also positive for antifilarial IgG4 antibodies.
CONCLUSION: Antifilarial IgG4-ELISA could detect 4.6 times more positive cases than the microfilaria detection method. With appropriate cut-off values that eliminate cross-reactivities, this serological tool is very useful for Brugia malayi prevalence surveys and diagnosis.
Tuberculosis: clinical manifestations and outcomes

Nissapatorn V, Kuppusamy I, Anuar AK, Quek KF, Latt HM

Southeast Asian J. Trop. Med. Public Health, 2003;34 Suppl 2:147-52.
PMID: 19238668

A total of 290 HIV/AIDS patients were recruited into this retrospective study, which was carried out at the National Tuberculosis Center (NTBC), Kuala Lumpur. The age range was 18 to 75 years with a mean age of 36.10 (SD +/- 7.44) years. Males outnumbered females by a ratio of 31:1. In this study, the majority of patients were male (96.9%), Malay (47.2%), single (66.9%), unemployed (81%), and smoked (61.4%). The main risk marker identified was injecting drug use (74.5%). The most common clinical manifestations were cough, fever, sputum, lymphadenopathy, and chest infiltrations. More than half of the patients (85.9%) were diagnosed with localized tuberculosis (pulmonary) and the others (14.1%) had extra-pulmonary or disseminated tuberculosis. At the time of this study, the majority of the patients (16.9%) had CD4 cell counts of less than 200 cell/mm3, with a median of 221 cell/mm3. Clinical outcomes demonstrated that among those who survived, 11.0% and 20.7% of the patients had completed treatment either > or = 6 or > or = 9 months, respectively, whereas 54.8% of patients were lost to follow-up, including 0.7% for MDR-TB. Diagnostic criteria for tuberculosis in this study were mainly clinical symptoms/signs and chest x-ray findings (31.0%).
Fulltext Tuberculosis: a resurgent disease in immunosuppressed patients

Nissapatorn V, Kuppusamy I, Josephine FP, Jamaiah I, Rohela M, Khairul Anuar A

Southeast Asian J. Trop. Med. Public Health, 2006;37 Suppl 3:153-60.
PMID: 17547073

A total of 136 patients, 67 HIV, 69 diabetes mellitus (DM) with or without (+/-) end-stage renal disease (ESRD), were registered for tuberculosis treatment at the National Tuberculosis Center (NTBC) from May to December, 2003. Ages ranged from 21-78 years (median 57.7 years) in TB/DM patients, and 21-62 (mean 37.6 +/- 8.3 years) in TB/HIV patients. TB was significantly found in younger and single HIV patients, but in older and married DM patients (p<0.05). Male patients in both groups were strongly associated with TB, while females more commonly had TB with DM (p<0.05). The majority of these patients were Malays, unemployed, and resided in Kuala Lumpur territory; however, no statistically significant difference was found between the 2 groups. Smoking, IVDUs and hepatitis C virus (HCV) infection were more significantly found in TB/HIV patients and further analysis showed that pulmonary TB was strongly associated with HCV infection in these patients (p<0.05). Pulmonary TB (62; 89.9%) was the most common type found in both groups and was a markedly more common disease location in TB/DM patients, while extrapulmonary TB (21; 31.3%) and miliary TB (14; 21%) were significantly higher in TB/HIV patients. Cough with or without sputum, fever and loss of appetite and/or weight were common clinical presentations in both groups. Nevertheless, fever (54; 80.6%) and lymphadenopathy (17; 25.4%) were significantly related to TB/HIV patients (p<0.05). Interestingly, the presence of BCG vaccination and positive tuberculin skin test were stronger in TB/HIV (27; 40.3%) and TB/DM (20; 29%) patients, respectively (p<0.05). Overall, regular 6-, 9- and 12-months' anti-tubercular therapy (ATT) were routine practice, and EHRZ+B6 was the most common regimen used. The highest percentage of patients with treatment success were in both groups with 6 months' ATT; however, a significantly higher percentage was found in TB/DM (24; 34.8%) than TB/HIV (13; 19.4%) (p<0.05). A success rate of 15 (21.7%) was noted for TB/DM patients with 9 months' ATT, which was similar to both groups with the 12-month regimen. A higher percentage failure rate (lost to follow-up) was seen in TB/HIV (19; 28.4%) patients. Nine patients were reported to have anti-tubercular-drug side-effects, such as drug-induced hepatitis, blurred vision, and skin rash. No cases of drug resistance or death were notified among these patients.
Fulltext Tuberculosis in diabetic patients: a clinical perspective

Nissapatorn V, Kuppusamy I, Jamaiah I, Fong MY, Rohela M, Anuar AK

Southeast Asian J. Trop. Med. Public Health, 2005;36 Suppl 4:213-20.
PMID: 16438212

This retrospective and descriptive study was a report on the clinical situation of tuberculosis in diabetic patients, with 1,651 patients recruited. The mean age of TBDM patients was significantly higher than that of non-diabetic patients (p<0.05). Moreover, TBDM patients had a higher ratio of male to female than the other group. The significant proportion of TB appeared to increase steadily with age in diabetic patients compared to non-diabetic ones (p<0.05). However, they showed similarities in terms of sex, race, marital status, present address, and occupation. A higher percentage of pulmonary tuberculosis (91.4%) was shown in the TBDM group. We found that both groups had no differences in the radiological findings, with opacity or cavity of the upper lobe involvement being 89% and 91% in TBDM and non-diabetic groups, respectively. TBDM patients were shown to have more treatment success (33.3%), particularly the pulmonary type of tuberculosis in the longer duration ( 9 months). Further findings demonstrated that a lower proportion of the TBDM group defaulted in their treatment (19.8%) and experienced resistance to anti-tubercular therapy (1.4%) compared to non-diabetics.
Tuberculosis in HIV/AIDS patients: a Malaysian experience

Nissapatorn V, Kuppusamy I, Sim BL, Quek KF, Khairul Anuar A

Southeast Asian J. Trop. Med. Public Health, 2005 Jul;36(4):946-53.
PMID: 16295550

This retrospective study was conducted at the National Tuberculosis Center (NTBC) where 252 HIV-positive patients coexisting with tuberculosis (TB/HIV) were examined. We found that patients with pulmonary (PTB) and extrapulmonary tuberculosis (EPT) had similar mean age. A higher sex ratio between male to female (10.7:1) was observed in patients with PTB. The other characteristics of patients with pulmonary and extrapulmonary tuberculosis were not statistically different from each other. Cough (88%) and hemoptysis were the most common presenting symptoms, significantly related to patients with PTB. Lymphadenopathy (33.5%) was the most common sign in patients with EPT. The majority of patients with pulmonary and extrapulmonary tuberculosis had CD4 cell counts of less than 200 cells/mm3 (range 0-1,179 with a median of 57 cells/mm3). Lung (89%) and miliary (55.6%) forms were the most frequent disease locations in patients with PTB and EPT, respectively. A higher percentage of patients with PTB (42%) were treated successfully with short-course (6 months) therapy, whereas in patients with EPT (43%) needed a longer period (9 months) for successful treatment. Of the patients who defaulted treatment, a higher proportion (87%) had PTB. No MDR-TB or relapse cases were found in this study.
Toxoplasmosis: prevalence and risk factors

Nissapatorn V, Noor Azmi MA, Cho SM, Fong MY, Init I, Rohela M, et al.

J Obstet Gynaecol, 2003 Nov;23(6):618-24.
PMID: 14617462

A total of 200 pregnant women were recruited in this cross-sectional study. The overall seroprevalence of toxoplasmosis in pregnant women was found to be 49%, in which 39%, 4% and 6% for anti-Toxoplasma IgG, IgM and both anti-Toxoplasma IgG and IgM antibodies, respectively. We found the differences in Toxoplasma seroprevalence rates among the races were significant: the highest rate was in the Malays (55.7%), followed by the Indian (55.3%) and the Chinese (19.4%) (P<0.05) populations. An increase in Toxoplasma seroprevalence with increasing parity was detected (P<0.05). Women with no children had a prevalence of 39.7%, while women with one or more than two children had a prevalence of 44.2% and 62.9%, respectively. In this study, there was no significant association between Toxoplasma seroprevalence and various possible risk factors in pregnant women (P>0.05). When multivariate analysis was performed, no significant association between Toxoplasma seroprevalence and history of contact with cats, consumption of undercooked meat and blood transfusion was found (P>0.05). We did not find any newly diagnosed cases of acute acquired toxoplasmosis in pregnancy during the study period.
Fulltext Toxoplasmosis in HIV/AIDS patients in Malaysia

Nissapatorn V, Lee CK, Cho SM, Rohela M, Anuar AK, Quek KF, et al.

Southeast Asian J. Trop. Med. Public Health, 2003;34 Suppl 2:80-5.
PMID: 19238664

Three hundred and one sera of HIV/AIDS patients were tested for anti-Toxoplasma IgG antibody by ELISA technique. The seroprevalence of toxoplasmosis was 41.2% (95% CI: 35.5-46.9) in HIV/AIDS patients. The seroprevalence was significantly higher in the Malay (57.9%) than the Chinese (38.7%), followed by the Indian patients (29.6%) (p<0.05). No possible risk factor, such as contact with cats, consumption of uncooked meat, and history of blood transfusions was found to have any significant association with the presence of anti-Toxoplasma antibody in the study sample (p>0.05). Multivariate analysis was employed to find any association between Toxoplasma seroprevalence and a single subject having single or multiple risk factors. It was found that the association was not statistically significant (p>0.05). Among the HIV/AIDS study samples, 124 (41.2%) samples were found to have positive anti-Toxoplasma antibody, the association between the presence of anti-Toxoplasma antibody and CD4 cell count was determined but no statistically significant association was found (p>0.05). During the study period, only one case of active CNS toxoplasmosis was registered and the diagnostic criteria included: clinical presentations, CT scan finding, serological evidence of anti-Toxoplasma IgG antibody, and respose to anti-Toxoplasma therapy.
Fulltext Toxocara seroprevalence and childhood asthma among Malaysian children

Chan PW, Anuar AK, Fong MY, Debruyne JA, Ibrahim J

Pediatr Int, 2001 Aug;43(4):350-3.
PMID: 11472577 DOI: 10.1046/j.1442-200X.2001.01421.x

BACKGROUND: The larva of Toxocara spp., a common animal roundworm, may infect non-compatible hosts, causing a profound immunological reaction with marked eosinophil and IgE responses, not unlike in atopy. In this study, we determined the seroprevalence of Toxocara exposure in 66 asthmatic and 58 non-asthmatic children.
METHODS: Exposure to Toxocara was determined by examining the serum samples of the children for specific IgG antibodies to L2 Toxocara larvae, using a commercially available diagnostic kit.
RESULTS: There was no significant difference in the mean age, sex, social class, residence type and presence of domestic pets at home between the two children groups. Children with bronchial asthma were observed to have higher Toxocara seropositivity than that of the non-asthmatic controls (21.2 vs 8.6%, P=0.047).
CONCLUSION: The observed relationship between exposure to Toxocara infection and bronchial asthma in Malaysian children warrants further evaluation. An understanding of any possible contribution to the pathogenesis of childhood asthma provides a potential avenue for prevention.
Study site: Paediatric Asthma clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
Towards sustainable use of potassium in pineapple waste

Ahmed OH, Husni MH, Anuar AR, Hanafi MM

ScientificWorldJournal, 2004 Nov 20;4:1007-13.
PMID: 15578124

Due to the 1997/98 haze problem in South-East Asia and the increasing need for sustainable food production and development, the usual management of crop residues (including pineapple wastes) through burning is prohibited. As a result, the need for alternative uses of pineapple wastes in pineapple production has been emphasized. This study investigated an environmentally friendly means of recycling pineapple leaves for agricultural use. Pineapple leaves were shredded and composted in a composting drum for 30 days. Part of the shredded leaves was ashed in a muffle furnace for 4 h. Humic acid (HA), K-fulvate, and K in HA and compost were analyzed using standard procedures. An ash to water ratio of 1:7 was used to extract 0.1 molar (M) KOH from the shredded leaves. The 0.1 M KOH contained 50% K and was able to extract 20% HA from the composted pineapple leaves. Percent K in the fulvate using 0.1 M KOH was 43. Besides serving as a foliar spray (supplement soil application K fertilizers), source of K for freshwater fish (e.g., tilapia), the HA produced can be used as a soil conditioner. Studies show that between 0.05-0.01 g of HA per kg soil retards runoff by 36% in sandy and sandy loam soils. The K-fulvate can be used as a fluid fertilizer. In addition, the pH of 2 of the K-fulvate suggests it could be used to dissolve phosphate rocks, particularly those in the arid regions where high soil pH does not facilitate the dissolution of these important rocks that serve as one of the sources of phosphorus fertilizer in agriculture.
The prevalence of malnutrition and geo-helminth infections among primary schoolchildren in rural Kelantan

Zulkifli A, Anuar AK, Atiya AS, Yano A

Southeast Asian J. Trop. Med. Public Health, 2000 Jun;31(2):339-45.
PMID: 11127336

A cross-sectional study of the nutritional status of schoolchildren aged 7-10 years from the Kuala Betis Resettlement Scheme in Gua Musang, Kelantan was done. A total of 291 schoolchildren were examined but only 183 (62.9%) fecal samples were returned for geo-helminth infection analysis. The prevalence of stunting was 40.4% and underweight was 28.4%. A total of 127 schoolchildren (69.4%) were positive for at least one of the 3 geo-helminth infections. The most common geo-helminth was Ascaris lumbricoides (62.8%), followed by Trichuris trichiura (38.9%), and hookworm infection was relatively low (12.6%). All the anthropometric indices measured were lower in the geo-helminth infected children compared to the uninfected childen, except for the weight-for-height z-score. However the differences were insignificant Geo-helminth infections may not be a significant factor in malnutrition of these schoolchildren. However, with the availability of safe, efficacious and cheap broad spectrum anthelmintics, regular mass treatment should be given in selected areas where the prevalence of geo-helminth infections is still high, so that these schoolchildren will be able to achieve their growth potential during their school years.
Fulltext The nutritional status of children in resettlement villages in Kelantan

Zulkifli A, Khairul Anuar A, Atiya AS

Southeast Asian J. Trop. Med. Public Health, 1999 Mar;30(1):122-8.
PMID: 10695800

A cross-sectional survey of the nutritional status of children aged 1-10 years old from the Kuala Betis resettlement villages was carried out. A total of 620 children were examined, of which 329 were preschool children and 291 were schoolchildren. The age was determined and anthropometric measurements such as weight, height and MUAC were taken. The nutritional status was assessed by looking at the distributions of the z-scores of weight-for-age (WAZ), height-for-age (HAZ) and weight-for-height (WHZ) in relation to the growth charts of the National Center for Health Statistics reference population. It was found that the nutritional status of the Orang Asli children was poor, with a prevalence of 33.7-65.3% underweight, 55.3-74.4% stunting and 4.4-29.7% wasting based on the NCHS reference values. The prevalence of malnutrition among the Malay children was lower, underweight--7.3-34.1%, stunting--9.8-34.1% and wasting--1.7-17.1%. The nutritional status of the Orang Asli children were poorer compared to the Malay children. More preschool Orang Asli children were stunted compared to the Orang Asli schoolchildren. This may be due to the poor economic base of the Orang Asli community during the transformation period after resettlement. A comprehensive primary health care program is essential, especially targeting the preschool Orang Asli children in these resettlement villages.
The level of knowledge and acceptance towards the COVID-19 vaccine among the community in Johor Bahru, Johor

Mohd Anuar AH, Mohamad Anuar NN, Isa SNI, Bahari M

Med J Malaysia, 2024 Mar;79(Suppl 1):88-95.
PMID: 38555891

INTRODUCTION: Several necessary initiatives have been made to create a readily available vaccine against the Coronavirus Disease 2019 (COVID-19) worldwide pandemic. However, the vaccination program's success is dependent on the population's willingness as well as their knowledge of vaccination. Hence, the present study aimed to assess the level of knowledge and acceptance towards the COVID-19 vaccine among the community in Johor Bahru, Johor.
MATERIALS AND METHODS: A cross-sectional study was conducted using an online survey between February and May 2022, with 423 respondents. The questionnaire consisted of socio-demographic, assessment of knowledge level and acceptance level towards COVID-19 vaccine. The descriptive analysis and non-parametric tests were employed to investigate the study outline objectives.
RESULTS: Of all 423 participants, 293 (69.3%) of the participants had a high level of knowledge about the COVID- 19 vaccine (median knowledge score 6; IQR = 3), and 239 (56.5%) were reported to have a low level of vaccine acceptance (median acceptance scores 4; IQR=2). The knowledge level towards the COVID-19 vaccine was significantly associated with the vaccine acceptance level (p<0.001).
CONCLUSION: The community's level of knowledge towards COVID-19 vaccine was high; however, the vaccine acceptance was low.
The influence of host stage and sex upon the size and composition of the thelastomatids parasitic in the hindgut of Periplaneta americana L. and Neostylopyga rhombifolia (Stoll)

Anuar AK, Rodzoh S

Med J Malaysia, 1978 Sep;33(1):76-85.
PMID: 750901
Fulltext Suppression of Excited ϒ States Relative to the Ground State in Pb-Pb Collisions at sqrt[s]_{NN}=5.02 TeV

Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.

Phys Rev Lett, 2018 Apr 06;120(14):142301.
PMID: 29694144 DOI: 10.1103/PhysRevLett.120.142301

The relative yields of ϒ mesons produced in pp and Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, ϒ(2S) and ϒ(3S), to the ground state, ϒ(1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [ϒ(nS)/ϒ(1S)]_{Pb-Pb}/[ϒ(nS)/ϒ(1S)]_{pp}, are measured to be 0.308±0.055(stat)±0.019(syst) for the ϒ(2S) and less than 0.26 at 95% confidence level for the ϒ(3S). No significant ϒ(3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as ϒ transverse momentum and rapidity. No significant dependencies are observed.
Fulltext Suppression and azimuthal anisotropy of prompt and nonprompt [Formula: see text] production in PbPb collisions at [Formula: see text][Formula: see text]

Khachatryan V, Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, et al.

Eur Phys J C Part Fields, 2017;77(4):252.
PMID: 28515669 DOI: 10.1140/epjc/s10052-017-4781-1

The nuclear modification factor [Formula: see text] and the azimuthal anisotropy coefficient [Formula: see text] of prompt and nonprompt (i.e. those from decays of b hadrons) [Formula: see text] mesons, measured from PbPb and pp collisions at [Formula: see text] [Formula: see text] at the LHC, are reported. The results are presented in several event centrality intervals and several kinematic regions, for transverse momenta [Formula: see text] [Formula: see text] and rapidity [Formula: see text], extending down to [Formula: see text] [Formula: see text] in the [Formula: see text] range. The [Formula: see text] of prompt [Formula: see text] is found to be nonzero, but with no strong dependence on centrality, rapidity, or [Formula: see text] over the full kinematic range studied. The measured [Formula: see text] of nonprompt [Formula: see text] is consistent with zero. The [Formula: see text] of prompt [Formula: see text] exhibits a suppression that increases from peripheral to central collisions but does not vary strongly as a function of either y or [Formula: see text] in the fiducial range. The nonprompt [Formula: see text] [Formula: see text] shows a suppression which becomes stronger as rapidity or [Formula: see text] increases. The [Formula: see text] and [Formula: see text] of open and hidden charm, and of open charm and beauty, are compared.
Fulltext Study of the underlying event in top quark pair production in p p collisions at 13 Te

Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Asilar E, Bergauer T, et al.

Eur Phys J C Part Fields, 2019;79(2):123.
PMID: 30863200 DOI: 10.1140/epjc/s10052-019-6620-z

Measurements of normalized differential cross sections as functions of the multiplicity and kinematic variables of charged-particle tracks from the underlying event in top quark and antiquark pair production are presented. The measurements are performed in proton-proton collisions at a center-of-mass energy of 13 Te , and are based on data collected by the CMS experiment at the LHC in 2016 corresponding to an integrated luminosity of 35.9 fb - 1 . Events containing one electron, one muon, and two jets from the hadronization and fragmentation of b quarks are used. These measurements characterize, for the first time, properties of the underlying event in top quark pair production and show no deviation from the universality hypothesis at energy scales typically above twice the top quark mass.
Fulltext Study of dijet events with a large rapidity gap between the two leading jets in pp collisions at s = 7 TeV

Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.

Eur Phys J C Part Fields, 2018;78(3):242.
PMID: 31264999 DOI: 10.1140/epjc/s10052-018-5691-6

Events with no charged particles produced between the two leading jets are studied in proton-proton collisions at s = 7 TeV . The jets were required to have transverse momentum p T jet > 40 GeV and pseudorapidity 1.5 < | η jet | < 4.7 , and to have values of η jet with opposite signs. The data used for this study were collected with the CMS detector during low-luminosity running at the LHC, and correspond to an integrated luminosity of 8 pb - 1 . Events with no charged particles with p T > 0.2 GeV in the interval - 1 < η < 1 between the jets are observed in excess of calculations that assume no color-singlet exchange. The fraction of events with such a rapidity gap, amounting to 0.5-1% of the selected dijet sample, is measured as a function of the p T of the second-leading jet and of the rapidity separation between the jets. The data are compared to previous measurements at the Tevatron, and to perturbative quantum chromodynamics calculations based on the Balitsky-Fadin-Kuraev-Lipatov evolution equations, including different models of the non-perturbative gap survival probability.
Fulltext Study of central exclusive production in proton-proton collisions at s = 5.02 and 13TeV

Sirunyan AM, Tumasyan A, Adam W, Ambrogi F, Bergauer T, Brandstetter J, et al.

Eur Phys J C Part Fields, 2020;80(8):718.
PMID: 32834020 DOI: 10.1140/epjc/s10052-020-8166-5

Central exclusive and semiexclusive production of pairs is measured with the CMS detector in proton-proton collisions at the LHC at center-of-mass energies of 5.02 and 13TeV. The theoretical description of these nonperturbative processes, which have not yet been measured in detail at the LHC, poses a significant challenge to models. The two pions are measured and identified in the CMS silicon tracker based on specific energy loss, whereas the absence of other particles is ensured by calorimeter information. The total and differential cross sections of exclusive and semiexclusive central production are measured as functions of invariant mass, transverse momentum, and rapidity of the system in the fiducial region defined as transverse momentum and pseudorapidity . The production cross sections for the four resonant channels , , , and are extracted using a simple model. These results represent the first measurement of this process at the LHC collision energies of 5.02 and 13TeV.
Study of Jet Quenching with Z+jet Correlations in Pb-Pb and pp Collisions at sqrt[s]_{NN}=5.02 TeV

Sirunyan AM, Tumasyan A, Adam W, Asilar E, Bergauer T, Brandstetter J, et al.

Phys Rev Lett, 2017 Aug 25;119(8):082301.
PMID: 28952777 DOI: 10.1103/PhysRevLett.119.082301

The production of jets in association with Z bosons, reconstructed via the μ^{+}μ^{-} and e^{+}e^{-} decay channels, is studied in pp and, for the first time, in Pb-Pb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The Pb-Pb collisions were analyzed in the 0%-30% centrality range. The back-to-back azimuthal alignment was studied in both pp and Pb-Pb collisions for Z bosons with transverse momentum p_{T}^{Z}>60 GeV/c and a recoiling jet with p_{T}^{jet}>30 GeV/c. The p_{T} imbalance x_{jZ}=p_{T}^{jet}/p_{T}^{Z}, as well as the average number of jet partners per Z, R_{jZ}, was studied in intervals of p_{T}^{Z}. The R_{jZ} is found to be smaller in Pb-Pb than in pp collisions, which suggests that in Pb-Pb collisions a larger fraction of partons associated with the Z bosons fall below the 30 GeV/c p_{T}^{jet} threshold because they lose energy.

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links