Search or add a thesis

Advanced Search (Beta)
Home > Probing New Physics Through Semileptonic Flavor Changing Neutral Current Transition

Probing New Physics Through Semileptonic Flavor Changing Neutral Current Transition

Thesis Info

Access Option

External Link

Author

Ishtiaq Ahmed

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2012

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2440/1/2552S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727015419

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


In this thesis, the exclusive semileptonic rare B-mesons decays which are induced by the flavor changing neutral current transition (FCNC) have been studied within and beyond the Standard Model (SM). To probe physics beyond the SM, B → K ∗ + − , B → K1 + − level, these FCNC transitions arises as b → s ∗ , B → K2 + − + − and Bc → D∗ s + − decays are considered. At quark and, in the SM, are forbidden at tree level but are allowed at loop level through Glashow-Iliopoulos-Maiani (GIM) mechanism. Moreover, FCNC transitions are further suppressed due to the fact that they are directly proportional to the off diagonal elements of the Cabibo Kobayashi Maskawa (CKM) matrix. Because of these two conditions FCNC transitions are relatively rare and become important to investigate the physics beyond the SM, usually known as new physics (NP). The important points of the thesis are in order: • We study the exclusive channel of flavor changing neutral current transition (FCNC) i.e. B → K ∗ + − in the frame work of a family of non-universal Z model. In this model, the Z boson couplings to the fermions could lead to FCNC transition at tree level. In addition, the off-diagonal elements of these effective chiral Z couplings can contain new weak phases that provide a new source of CP violation and, therefore, could explain the CP asymmetries in the current high energy colliders. In this context, we have studied the polarized and unpolarized CP violation asymmetries for the said decay. These asymmetries are highly suppressed in the standard model but significantly enhanced in the Z model. In addition to the CP violation asymmetries, the single lepton polarization asymmetries are also studied and found them sensitive to the couplings of the Z boson. Finally, it is analyzed that all these asymmetries which will hopefully be tested at LHC can serve to probe the non-universal Z model, particularly, the accurate measurements of these asymmetries may play a crucial role to extract the precise values of the coupling parameters of Z boson. • The sensitivity of the zero position of the forward backward asymmetry AFB for the exclusive B → K1 (1270)μ+ μ− decay is examined by using most general non-standard 4-fermion interactions. Our anal- ysis shows that the zero position of the forward backward asymmetry is very sensitive to the sign and size of the Wilson coefficients corresponding to the new vector type interactions, which are the counter partners of the usual Standard Model operators but have opposite chirality. In addition to these, the other significant effect comes from the interference of Scalar-Psudoscalar and Tensor type operators. These results will not only enhance our theoretical understanding about the axial vector mesons but will also serve as a good tool to look for physics beyond the SM. • A detailed study of the impact of New Physics (NP) operators with different Lorentz structures, which ∗ are absent in the Standard Model Hamiltonian, on the B → K2 (1430)μ+ μ− decay is performed. In this context, the various observables such as branching ratio, forward-backward asymmetry of leptons, lepton ∗ polarization asymmetries and the helicity fractions of the final state K2 (1430) meson have been studied. We have examined the effects of new vector-axial vector, scalar-pseudoscalar and tensor type interactions for ∗ this decay B → K2 (1430)μ+ μ− by using the constraints on different NP couplings which come from the ̄ ̄ Bs → μ+ μ− , B → X s μ+ μ− and B → K ∗ μ+ μ− decays. It is found that the effects of V A, S P and T operators are significant on the zero position of AFB (q2 ) as well as on its magnitude. In addition to this these NP operators also give significant effects on the differential decay rate, lepton polarization asymmetries and ∗ helicities fractions of final state K2 (1430) meson. • The semileptonic Bc → D∗ s + − ( = μ, τ) decays have been studied in the Standard Model (SM) and in the Universal Extra Dimension (UED) model. In addition to the contribution from the Flavor Changing Neutral Current (FCNC) transitions the weak annihilation (WA) contribution is also important for this decay because ∗ of enhanced CKM matrix elements Vcb Vcs . It is found that the WA gives 6.7 times larger branching ratio than the penguin contribution for the decay Bc → D∗ μ+ μ− . The contribution from the WA and FCNC transitions s are parameterized in terms of the form factors. In this work we first relate the form factors through Ward identities and then express them in terms of g+ (0) which is extracted from the decay Bc → D∗ γ through QCD s sum rules approach. These form factors are then used to analyze the physical observables like branching ratio and helicity fractions of the final state D∗ meson in the SM. This analysis is then extended to the UED s model where the dependency of above mentioned physical observables depend on the compactification radius R. It is shown that the helicity fractions of D∗ are sensitive to the UED model especially when we s have muons as the final state lepton. This sensitivity is marked up at low q2 region, irrespective of the choice of the form factors. It is hoped that in the next couple of years LHC will provide enough data on the Bc → D∗ s + − channel, and then , these helicity fractions would serve as a useful tool to establish new physics predicted by the UED model.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

مولانا حبیب الرحمان عثمانی

مولانا حبیب الرحمن عثمانی
اس مہینہ کا سب سے بڑا علمی اور تعلیمی حادثہ دارالعلوم دیوبند کے مہتمم حضرت مولانا حبیب الرحمان عثمانی کی وفات ہے، دیوبند کا مدرسہ عالیہ اگر ہمارے پرانے مذہبی مدارس کی روح ہے تو اس میں شک نہیں کہ اس مدرسہ عالیہ کی روح حضرت مولانا حبیب الرحمان صاحب عثمانی تھے، مرحوم شاید اس مدرسہ کے مقدس بانیوں کی آخری یادگار تھے، وہ ایک مشہور عالم متبحر، اور عربی کے ادیب تھے، دیگر علوم کے علاوہ عربی نظم و نثر پر ان کو یکساں قدرت حاصل تھی، اسلامی تاریخ سے بھی ان کو ذوق کامل تھا، اردو انشاء میں ان کا سلیقہ خاصہ تھا۔ رسالہ القاسم ان کی علمی کوششوں کی پوری تاریخ ہے، ان کی اردو تصانیف ’’اسلامی کی اشاعت کیونکر ہوئی‘‘ ایک ضخیم کتاب ہے، ان سب کے ساتھ جس چیز میں وہ اپنی جماعت میں سب سے زیادہ ممتاز تھے، وہ ان کا تدبر حسن سیاست اور نظم و نسق کی قوت تھی، انہوں نے ۱۳۳۵؁ھ سے ۱۳۴۸؁ھ تک جب تک ان کی جان میں جان رہی، مدرسہ دیوبند کے اہتمام اور نظم و نسق کی خدمت انجام دی۔
ان کی محنت، جان کا ہی اور مسلسل خدمات کے ساتھ ساتھ اگر ان کی جسمانی مخافت، کمزوری اور دائم المرضی کو دیکھا جائے تو تعجب ہوتا تھا کہ کیونکر وہ اس بارگراں کو اٹھائے ہوئے ہیں، ان سب سے مافوق ان کا اخلاص، تقویٰ، تواضع اور ہر ایک سے حسن خلق کا برتاؤ تھا، راقم الحروف کو مولانا سے سب سے پہلے اپنے ختم طالب العلمی کے بعد ہی دیوبند میں ۱۹۰۸؁ء میں ملنے کا اتفاق ہوا، اس وقت سے لے کر آخر تک ان کا یکساں طریق محبت قائم رہا، سب سے آخری دفعہ اسی سال علی گڑھ میں ان کی زیارت ان کے ہم نام نواب...

قرآنی اصولوں کی روشنی میں معاشرتی استحکام

Islam is the religion of nature. It not only approves the social interaction among the masses, but also helps in its development towards positive ends. Islam has given natural and universal principles which help its followers to develop a harmonious society, discouraging all the attempts to divide the society into different sections. Islamic society is based upon the following fundamental principles i. E equality, harmony of thoughts, justice, amar-bilmaaruf-wa-nahi-anilmunkar (ask for good and forbid from evil), unity, sense of responsibility, virtue and evil, abolition of sectarianism & fulfillment of promises, reflecting the universality of the religion, Islam. Pakistan today, is facing various social problems like terrorism, corruption, poverty, unemployment, broken families, sectarianism, onslaught of western culture and demand of unrestricted liberty by womenfolk. The moral degradation of the society is due to the fact that the true Islamic spirit and moral teachings and trainings of Islam have not been applied with true mind and honest intentions. The moral values are ignored by the media which is the cause of great concern.

Studying the Genetic Basis of Sporadic Breast Cancer Metastasis

Metastasis is the most lethal attribute of breast cancer and is responsible for majority of cancer related deaths. Numbers of metastasis suppressor genes that act to prevent or control metastasis have been identified in several types of cancers including breast cancer. This study was designed to screen three metastasis suppressor genes (DRG1, PTEN and gelsolin) for germ line mutations in sporadic breast cancer cases of Pakistani population. For expressional studies these genes were screened in both Pakistani as well as in British cohort. Three different study groups were recruited for this study. Cohort 1 was from Pakistani population, comprised of 350 blood samples and used for mutational analysis by polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP). Amplified products showing altered mobility patterns were sequenced and analyzed. For mRNA expression analysis, two different cohorts, (cohort 2 & cohort 3) from two different populations were used. Cohort 2 was from Pakistani population and comprised of 60 tissue samples while tumor matched normal adjacent tissues were used as control. Cohort 3 was from British population and comprised of 114 breast cancer tissues and 31 normal background tissues. Cohort 2 and 3 were screened by using real time quantitative polymerase chain reaction (qPCR) and data obtained was compared according to patients’ outcome and survival. Additionally, DRG1 expression was targeted in vitro using ribozyme transgene technology to explore the function of DRG1 in two human breast cancer cell lines. In this study using cohort 1, mean age of patients was calculated as 47±1.1 years, age at menarche as 13±0.1 years and mean age of post menopausal patients at menopause was calculated as 45±0.5 years. After Single Strand Conformational Polymorphism (SSCP), 57 samples showing altered mobility patterns were observed in DRG1. Splice site non-synonymous substitution and frame shift mutations were observed on exon 1 and exons 3, 4, and 5 respectively. Overall, clear majority of the sequenced mutations, 51 mutations out of 57 were frame shift mutations, which were deletions and 6 were splice site substitution mutations. Deletion mutation 459A/- was detected with highest frequency among all variations (0.36). Most prevalent mutation among premenopausal patients was frame shift mutations which were 369A/-, 377A/-, 387A/- in exon 4. While frame shift mutation 459A/- in exon 5 was most prevalent among postmenopausal patients. When analyzed according to age group frame shift xmutations in exon 4 (369A/-, 377A/-, 387A/-) was found most common in age <40 years. While 459A/- in exon 5 was wide spread among patients >40 years of age. It was observed that DRG1 expressed aberrantly in clinical breast tumor tissues in both cohorts 2 and 3 and was found to be significantly down regulated compared to control tissues. A highly significant link was seen between low levels of DRG1 expression and metastatic development. Patients who died of breast cancer also showed significant down regulation of DRG1 in cohort 3. Sequencing analysis revealed nineteen different types of mutations in different regions of PTEN (in exons 2, 4, 5, 6, 7 and splicing sites of intron 2 and 4 and also in the 3’ UTR region), including 3 silent, 8 missense, 2 frame shift and 6 splice site variations. Among the observed variations in this study, three missense mutations have already been reported i.e. 319G>A (Asp106Asn), 389G>A (Arg129Gln) and 482G>A (Arg160Lys) in different populations. Substitution at 3’ UTR region of PTEN 2634 T>A was observed with a highest frequency (0.139). Most common mutation in premenopausal patients was frame shift mutation that was -/A in exon 7. While substitution mutation T>A in 3’UTR region was most prevalent among postmenopausal patients. Most prevalent mutation among patients in age group <40 years was substitution mutation that was T>A in 3’UTR. While -/A, mutation in exon 7 was most prevalent in patients >40 years of age. Significant low levels of PTEN were observed in low grade tumor and in patients with poor prognosis in cohort 2. No significant difference was observed in transcript levels of PTEN, when analyzed according to grades, NPI value and TNM staging in cohort 3. Different types of mutations were observed in gelsolin which include 3 non- synonymous substitutions, 1 synonymous substitution and 10 frame shift mutations (comprising of 4 duplications, 5 deletions and 1 insertion) that were located in exons 4, 6, 7, 8, 10, 11, 14. Insertion mutation observed in exon 10 in 36 samples has highest frequency (0.116) among all mutations observed. Most common mutation found in premenopausal patients was frame shift mutation that was 539 A/- in exon 7. Frame shift mutation 897_898------/GCAGGC in exon 10 was most prevalent among postmenopausal patients. This variation was also the most prevalent mutation among patients in age group <40 years. While 987_988 C>T, 987_988 --/TC in exon 11 was wide spread among patients >40 years of age. Negative correlation of gelsolin xitranscript levels with development of metastasis in breast cancer patients in both cohorts (2 and 3) was observed. In vitro study revealed that knockdown of DRG1 results in significantly increased invasion and motility and decreased matrix-adhesion in MCF-7 cells. In this study different risk factors were also analyzed in association with breast cancer in patients but no association of these factors was observed in Pakistani population which is in accordance with many earlier studies conducted in this population. A wide range of germline mutations observed in DRG1, PTEN and gelsolin were found to be in important domains and might impair their functional activities. It can be suggested that these variations may play an important role in the pathogenesis and progression of breast cancer metastasis. Low expressional levels of these genes appear to be linked to development of metastasis and may be useful as a prognostic factor. In vitro data presented here indicate an involvement of the DRG1 gene in breast cancer progression and demonstrate a potential role of this gene in suppressing tumor metastasis.